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bOCU1ii t
FWS Biological
Report 88(12)
OCS Study
MMS 88-0063
An Ecological Characterization
of the Florida Panhandle
yhj ,-\L-,' ,, /-.7 '
ALABAMA
anta I d Chocaawhalchee Bay
Santa Rosa Island
Apalachlcola Bay
U.S. Department of the Interior
Fish and Wildlife Service and
Minerals Management Service
FWS Biological
Report 88(12)
OCS Study
MMS 88-0063
An Ecological Characterization
of the Florida Panhandle
Authors
Steven H. Wolfe
Jeffrey A. Reidenauer
State of Florida
Department of Environmental Regulations
Tallahassee, Florida
and
D. Bruce Means
The Coastal Plains Institute
Tallahassee, Florida
Prepared under Interagency Agreement
14-12-0001-30037
Published by
U.S. Department of the Interior
Fish and Wildlife Service, Washington
Minerals Management Service, New Orleans
October 1988
PREFACE
This report is one in a series that provides an ecological description of Florida's gulf coasts.
The watersheds described herein, with their myriad subtropical communities, produce
many benefits to people. The maintenance of this productivity through enlightened
resource management is a major goal of this series. This report will be useful to the many
people who have to make decisions regarding the use of the natural resources of the area.
Any questions or comments about or requests for this publication should be directed to
the following:
Information Transfer Specialist
National Wetlands Research Center
U.S. Fish and Wildlife Service
NASA Slidell Computer Complex
1010 Gause Boulevard
Slidell, Louisiana 70458
or
Public Information Unit (OPS-3-4)
Gulf of Mexico OCS Region
Minerals Management Service
1201 Elmwood Park Boulevard
New Orleans, Louisiana 70123-2394
CONVERSION FACTORS
Metric to U.S. Customary
Multiply by To Obtain
millimeters (mm) .............................0.03937 ............................ inches
centim eters (cm ) ..... ..... .. .... 0.3937 .............................inches
meters (m) ................ 3.281...........................feet
kilometers (km)....................... 0.6214 ............................ miles
square meters (m ) ................... 10.76 ................................ square feet
square kilometers (km) ..................0.3861 ..............................square miles
hectares (ha) .......................2.471 ................................ acres
liters (I) ................... 0................... 0 2 ..... .......... gallons
cubic m eters (m,) .... ................35.31 .................................. cubic feet
cubic meters (m ) ....... ..................0.0008110 ..................... acre-feet
milligrams (mg)................... 0.00003527 ....................ounces
gram s (g).................. .......... 0.03527 ..................... ..... ounces
kilogram s (kg) ................................ 2.205 .............................. pounds
m etric tons (mt) .... .................2205.0 ................... ............... pounds
m etric tons (mt) .............. .......1.102 .... ......................... short tons
kilocalories (kcal) ............................3.968 ................ .............. BTU
Celsius degrees ............. ....1.8(C) + 32.................... Fahrenheit degrees
U.S. Customary to Metric
Multiply by To Obtain
inches ....................... ..... ........ 25.40 ..... ........... ..... .... m illim eters
inches 54................2 54 ........ .. ........centimeters
feet (ft) ....................... ..... .. 3048 .... ................... m eters
fathom s ............ ............. .. 1.829 ......... ..................m eters
miles (mi) .......................... ..... 1 609 .... ..... ........... kilometers
nautical m iles (nm i) ...... ........... 1.852 .... .....................kilom eters
square feet (ift) .. .................. 0.0929 ...........................square meters
acres ............................ ...... .. 4047 ................... .. hectares
square m iles (m i) ................. ........2.590 ............................ ... square kilom eters
gallons (gal) ................ 3785 ................ liters
cubic feet (t) ..... ...... ...........0.02831 ..........................cubic meters
acre-feet ................ ............. 1233.0 ..... ............................cubic m eters
ounces (oz) ....................................28.35 ..... .... ................ gram s
pounds (b) ............... ............ 0.4536 .............. .... ....kilograms
short tons (ton) ...........................0.9072 .......................... metric tons
BTU ......................... .................... 2520 ..... ............... kilocaories
Fahrenheit degrees ... ............ 0.5556(F -32) ............... Celsius degrees
DISCLAIMER
The opinions and recommendations expressed in this report are those of the authors and
do not necessarily reflect the views of the U.S. Fish and Wildlife Service or the Minerals
Management Service, nor does the mention of trade names constitute endorsement or
recommendation for use by the Federal Government.
Library of Congress Cataloglng-ln-Publlcatlon Data
Wolfe, Steven H.
An Ecological characterization of the Florida panhandle.
(Biological report ;88 (12))
Supt. of Docs. no. : 49. 89/:88(12)
"Performed for U.S. Department of the Interior, Fish and Wild-
life Service, Research and Development, National Wetlands Research
Center, Washington, D.C. and Gulf of Mexico Outer Continental Shelf
Office, Minerals Management Service, New Orleans, LA."
"October 1988."
Bibliography: p.
1. Ecology--Florida. 2. Natural history--Florida.
I. Reidenauer, Jeffrey A. II. Means, D. Bruce. III. National Wetlands
Research Center (U.S.) IV. United States. Minerals Management
Service. Gulf of Mexico OCS Region. V. Title. VI. Series: Biological
report (Washington, D.C.); 88 (12)
QH105.F6W65 1988 574.5'09759'9 88-600088
Suggested citation:
Wolfe, S.H., J.A. Reidenauer, and D.B. Means. 1988. An ecological characterization of
the Florida Panhandle. U.S. Fish Wildl. Serv. Biol. Rep. 88(12); Minerals Manage.
Serv. OCS Study\MMS 88-0063; 277 pp.
CONTENTS
Page
P R E FA C E .................... ... .................................................................................... . ..... . .... ii
C O N V E R S IO N TA B LE ............................................ ........................ ........ .. ...........iv
FIG U R ES .............................. ...... .. .................................................................... .. xi
T A B L E S ......................... .......................................................................... .................. ..... .... xvi
ACRONYMS ................................ .............................................. .......xviii
ACKNOWLEDGMENTS ................... ............................xix
Chapter 1 Introduction
1.1 Purpose and O rganizatio n .. ...................................................................... .... ............. 1
1.2 The Florida Panhandle: O verview ....................................... ........ .............................. 1
Chapter 2 Geology and Physiography
2.1 Introduction ..... ...................... ...... .. .......... ................ ...... .... ...... ..... ... 3
2.2 Structure and G eologic Setting ...... ....................................... ................ ...... ...... ..........5
2 .3 S tratig rap h y .......................... ........................ ..... . .......... ................. ..... ...
2.3.1 Igneous and Paleozoic Rocks ................................................. ...................... 8
2.3 2 M esozoic Era ............................ ..... ............ ........................................ ........... 8
2.3.3 C enozoic Era .... ................ ......... ..... . ....................................... ...........9
a. P aleocene S series .............................................. ................................ ............9
b. Eocene Series .................................... ....................................... ..9
c. O ligocene Series .................... ... ........................................ 10
d. M iocene and Pliocene Series .......................................... ..............................11
e. Pleistocene to Recent ................................. ..................... .......................... .14
2.4 Physiography
2.4.1 The Northern Highlands.... .................................... ..................................... 16
2.4.2 The Marianna Lowlands ... ........ ............................. ........... ... 17
2.4.3 The Gulf Coastal Low lands ........................................ .......................................17
2.5 Regional Marine Geology .. ........ ........................................... ..............................18
2.6 Local Marine Geology
2.6.1 Ochlockonee Bay .............................................. ............................ ........... 23
2.6 2 Apalachicola Bay .. ....... ......... ... .............. ...... 24
2 .6 .3 S t. Josep h B ay ..... ....... ........................................................................... .....24
2.6.4 St. A ndrew Bay System ................................................................... ..................24
2.6.5 Choctaw hatchee Bay System ....................................... .......... ...........................26
2.6.6 Pensacola Bay System ............. ......... .... ............. ................26
2.7 Offshore (Outer Continental Shelf) Oil and Gas Reserves ....................................... 27
V
Panhandle Ecological Characterization
Chapter 3 Climate
3.1 Introduction ... .................... .... ...................30
3.2 Climatological Features
3.2.1 Tem perature .... ................................................ ................................................... 30
3.2.2 Rainfall ....................................................................... ...... .......... .... ..... .... 33
3.2.3 Winds
a. Normal wind patterns ......................................................................... .. 34
b. Hurricanes, tornadoes, and waterspouts.. ...... .................. .........................39
3 .2.4 Insolation ...................................................... .... ... ................ .. 40
a. Seasonal changes .......................................................... ...............................40
b. Atmospheric screening ........ ...................... .. ......................... ...41
3.2.5 Relative Humidity .......................................... ... ................... 42
3.3 Effects of Climate on Ecosystems ............................................43
3.4 Major Influences on Climate
3.4.1 Natural Influences on Climate.
a. Long-term influences on climate .................... ............................ ...... 44
b. Short-term influences on climate ............ ... ............................44
3.4.2 Anthropogenic Influences on Climate ................................ ... ....... ... 45
3.5 Summary of Climatic Concerns ...................... ......................... 46
3.6 A areas Needing Research ......................................................................................... .. 47
Chapter 4 Hydrology and Water Quality
4.1 Introduction .................... ... ........... ......... ............ ... .... ........... .......... ......... 48
4.1.1 Hydrology ................. .. ......... .... ... ... ........ .. ................. ........ .. 48
4.1.2 W after Q quality ............ ........... .......................................................... 50
a. Direct im portance ... ........... .. ........... ........................ .. ....... ..... 54
b. Indirect im portance ....................... ....................... ...... .......... .... 54
4.1 3 Hydrology and Water Quality Regulation and Management ................................54
4.2 Water Quality Parameters
4.2.1 Dissolved Oxygen (DO)
a. DO capacities ....... ........................................... ..................................... .... 56
b. O oxygen uptake respiration ............ ............................................. ...... ........56
c Oxygen uptake Biochemical Oxygen Demand (BOD) ........ ............... 57
4.2.2 pH ............................... ............................................57
4.2.3 Turbidity and Sedim ents ............................................................. .................... 59
4 2.4 D dissolved Solids ...... ........................... ............................................................. 59
a. Alkalinity ..... .......... ............................. .......... ........................ 60
b. Hardness .. .................. ........ .......................... .... ... ..........60
c Salinity .................. .. ..... ..... ..... ......................... ..... . ........60
d. Nutrients ...... .............. ... ....... ............................ 61
4.2.5 Temperature ...... .............. ............ .................................. ..........62
4 2 6 Other Contents..... ......... ................................... ................................... 62
4.3 Major Influences on Surface Water
4.3.1 Major Influences on Surface-water Hydrology
a. Natural factors affecting inland surface-water hydrology .............................63
b. Natural factors affecting coastal surface-water hydrology.................................. 65
c. Anthropogenic factors affecting inland surface-water hydrology ......................67
d. Anthropogenic factors affecting coastal surface-water hydrology ....................67
vi
Contents
Chapter 4 Hydrology and Water Quality (continued) Page
4.3.2 Major Influences on Surface-water Quality
a. Natural factors affecting inland surface-water quality ............................. .........67
b. Natural factors affecting coastal surface-water quality ...................... ........ 68
c. Anthropogenic factors affecting inland surface-water quality ............................68
d. Anthropogenic factors affecting coastal surface water quality ..........................69
4.4 Major Influences on Ground Water
4.4.1 Major Influences on Ground-water Hydrology
a. Natural factors affecting ground-water hydrology........... ....................... 69
b. Anthropogenic factors affecting ground-water hydrology .............................. 69
4.4.2 Major Influences on Ground-water Quality
a. Natural factors affecting ground-water quality .............................................71
b. Anthropogenic factors affecting ground-water quality ..................................72
4.5 Area-wide Surface-water Hydrology and Water Quality ................... ...................72
4.6 Area-wide Ground-water Hydrology and Water Quality ..................... ........ ........76
4.7 Basin Hydrology and Water Quality
4.7.1 Ochlockonee River Basin ................................... ..................................... .. 79
4.7.2 Coastal Area between Ochlockonee and Apalachicola Rivers .............................84
4.7.3 Apalachicola River Basin .. ....................................... ........................................85
4 .7 .4 C hipo la R iver B asin ................................................... ............................. ..... ...90
4.7.5 St. Andrew Bay and Coastal Area........................................................... ...........92
4.7.6 Choctawhatchee River Basin .......... .......................................................... ...............94
4 7.7 Choctawhatchee Bay and Coastal Area ......... ...................................... ..............96
4.7.8 Yellow River Basin ...................... ...... ..........................................................99
4.7.9 Blackwater River Basin ..... ............. ................................. ................. 97
4.7.10 Escam bia R iver Basin ..... .................. .............................. ......................... 101
4.7.11 Escam bia Bay and Coastal Area ......................................... ......................... .... 102
4.8 Potential Hydrology and Water Quality Problems
4.8.1 H ydrologic C concerns ................................................. ....................................... 104
4.8.2 Water Quality Concerns
a S surface w after ..................... ...... .......... .... ..................... ..................... 106
b. G round w after. ............................. ........................................................... 107
Chapter 5 Terrestrial Habitats
5 .1 In tro d u c tio n ......... ............................ ........ .. ...... .... .... .............................................1 0 9
5.2 Native Habitats
5.2.1 Longleaf C layhill Uplands ................................... ...... ... ....... ...................... 110
a F lo ra ................. ... .... ... ......................... ...... ..... ...... ... ..................... 1 1 0
b E co log y .............. .... .... ....... ........... ...... ........ .. ........................ ... 114
c S o ils ...................... ........... . ... .... ................... ...... ........ .................. 1 17
d. Trophic dynam ics ........... . ......... .... ................. ............................... 117
e Fa una .................. .... .... ..... ... ......... .............. .............. ........... .... 1 18
f. Rare and Endangered Species ........................................... .................. 118
5.2.2 Longleaf Sandhill Uplands ...................... ....... ........ ............ 118
a. Soils .......... ......... ............ .. ....... ...................... 118
b F lo ra ........... ..... .. ... ..... .. .... ... ......... ................. ....... 12 1
c E c o lo g y ........................... .. ... .................... ................................................... 1 2 1
d F a u n a ...................... .......... ............... ... ... ..... ........... ..............................1 2 2
Panhandle Ecological Characterization
Chapter 5 Terrestrial Habitats (continued) Page
5.2.3 Gully Eroded Ravines ................................................ ..... ...... .........................122
a. Soils ............................ ... ......................... ................ ...... 122
b. Ecology ................... .......... ............ .... .... ... ...... ......3...................... 123
c F lo ra ........................ ........... ............. ... ............ .. ................................ ... 1 2 4
d Fauna ............. .. .... ........ ....... ..................... ..... ... .... ..... . .. .. 124
5.2.4 Steepheads ................ .................. ... ........... ..... ....... .............. ...... 125
a. S oils ........................ ..... ........ .... ........... ......... .. .......................... ....... 126
b. Ecology ................... .......... .... ............. ........... ... 126
c F lo ra .......... ....... ... ... ... ... ....... ..................... .......... ................... ... 1 2 6
d Fa una ................................................ ... ..... ... ... ... .............. .. ....... .... 127
5.2.5 Beech-Magnolia Climax Forests ...................... ............. ....................127
a. Soils......... ............... .................... ......... ..... .... ........ 127
b E co logy ............................................... ..... .. ....... ... ...... ...... ..... ... 129
c F lo ra .......................... ......... .. ............ .......... .. .... ..... ... .. ... ........ ... .. ... 1 3 0
d Fauna ....................... ................. ..... ...... ....... ...................................130
5.2.6 Longleaf Flatwoods ........ ......... .............. ....... ............ ..... ....................132
a S o ils ................ . .......... ................. .......... ........... ........ ............. ...... .. ... 13 2
b. Ecology......................................................... ....................... .. .. .......132
c. Flora ............................ ...................... .. ........ .... ..... ....... .... 133
d. Fauna .................................. .......... ... ...... ........ ............ ... ..... .. 133
5.2.7 Beach, Dune, and Scrub ....................... ..................................137
a. Soils........................ ...... ........ ...... ......... ........ ........ .......... ......... .... 137
b. Ecology ... .. ..... ..... ........ ... ....... ......... .......... ...137
c. Flora ........................ ............. ..... ......... .. .... ....... .... 138
d. Fauna ....... ........... ... ............ ....... .......... ........ ..... ....... ........ 140
5 .2 .8 C a v e s .................... ................................. ...... .. ...... .... ....... ....... .. .. ... .. 1 4 0
a. Flora ................... .... .. ................ ...... ... .... .... .. ..... ........ ............. .......... ...... 141
b. Fauna .......................................... ......... ............. ............. ...... 142
5.3 Human-Created Habitats
5.3.1 Fallow Lands, Succession, and Mixed Hardwood Forests .............................. 142
a. Soils ........................................ .... .. .......... ................................. .... 142
b E ecology .................... .......... ............. ... .......... ......... .. ................... 142
c. Flora ...... ........... ... .................... ...... .. ....... ... .......... ........ . ..... .... 143
d. Fauna ................................. ....... .... ..... ... ....... ... ....... .... 143
5.3.2 Silvicultural Com m unities .............................. ....................................... ........... 144
a S o ils ................................... ......... ... ...... .. .... .. .... . 14 4
b. Ecology .......................... .............. ............ ... ............ 144
c. Flora ....................... .. .......... ........ ... .... ........ .. ...... .. .... ........... 144
d. Fauna ............... ............... ..... ... ... .......... . .... ...... .. ....1.. 45
Chapter 6 Freshwater Habitats
6 .1 In tro d uctio n .................................................................................. .................. ..... 14 6
6.2 Native Palustrine Habitats
6.2.1 Herb Bogs and Savannahs .. ........ ................................... 147
a. Flora ............................................ .... ...... ..... .................. 147
b. Fauna ............................. ............. ... ... ..... ................... 151
6.2.2 Shrub bogs, Titi Swamps, and Bay Swamps ................................. ............152
a. Bay sw am ps ......................................... .... 152
b T iti sw a m p s ........................................ ...................................................... 15 3
c. Fauna .............. .. ..... ........ .... ... .................... .... .... 154
viii
Contents
Chapter 6 Freshwater Habitats (continued) Page
6.2.3 Bottomland Hardwood Forests.................................................. 154
a E co logy ........................................................... ..... ......... .... ... .. .... 15 6
b F a u n a .................................... ........ ........ ...... ... .. ... .....-- . ... .... 159
6.3 Native Riverine Habitats ....................................... .............................................161
6.3.1 First-order Ravine Streams ............................................................... 161
a F lo ra ........................ ........... .... ... .... ...... .................. .. ............ .. ... .. 1 6 2
b. Fauna ............................... ... ................ .. ......... .. ............. 162
6.3.2 Alluvial Stream s and Rivers ............................................................ ............ ........162
a. Flora ............................... ........ .. .............. ..... ........... ... .... .. 163
b. Fauna ..... .................... .. ...... ......... . .. .................. ..... 163
6.3.3 Blackwater Streams ..... .................... .................... .... .... 165
a. Flora ................................... .... ......................... .. .......... 165
b. Fauna .............................. ..... ......... .... ........ ..... .. ......... 165
6.3.4 Spring-ed Stream s .......................................... ...................................... ... 166
a. S tream flora .... ...1........... ... .... ...................... .................... 167
b S tre a m fa u na ............................................................................ .................. ... 1 67
6.4 N active Lacustrine H habitats ............................................ ............................................. 167
6.4.1 Karst Lakes .................................... ....... ......... ....... ... ...... ....... 1. 168
a. Flora ............ ...... ........... .............................. ... ......... .... .. ..... 168
b F a u n a .................................................... .... ...................... ... ... .. .... 1 6 8
6.4.2 River Floodplain Lakes ....................................... .... ............... .. 169
a. Flora .................. ........................ .... .. .. ..... . 169
b. Fauna ............................ .................... .......................... ...1...169
6.4.3 Sw am p Lakes............................................. ..................... ... . .... ... 169
6.4.4 Ponds .......... .... ..... .......... ................... ..... .... ...... ........ ..... ... 169
a. Flora .............................................. ...... ..... .. 170
b. Fauna ............ ............................. .....1.. ........ .........170
6.4.5 Coastal Ponds ........................................................... 171
6.5 Subterranean Habitats
6.5.1 W ater-filled C aves ................................................................................. ....... 172
6.6 Human-Created Lacustrine Habitats ................................ 175
6.6.1 Im pounds ents ........................ ...................................................................... 175
a Flo ra ..................................... ....... ........... .......... ................ .... .. 176
b Fau na ........................... .. .............. ... .. .....1.... .... ... 176
Chapter 7 Estuarine, Saltwater Wetland, and Marine Habitats
7 .1 In tro d u c tio n .................. ........................................................................ ............. ..... 1 7 8
7.1.1 Tides and Salinity Ranges ........... ........... ...... ..........................179
7.2 Estuarine Habitats
7.2 .1 Introduction ...... .. .......... .... .....1........................................ 80
7.2.2 Brackish Marshes
a. Introduction............. ..... .. .. ......................... ..... ... . ... .... .. ... 180
b. V ascular species .................................................... ...... ................. ... 180
c. Associated fauna ................... ...................................................... 180
d. H um an im pacts ...................................................................... ..................... 180
7.2.2 Salt (or Tidal) Marshes
a. Introductio n .......................... ......... ........... ...... .. .. .......... ..... ... ...... 18 1
b. Major physiographic features .............. ..... .... ................................. 182
c. D distribution ................... ...... ... .. . ........ ..... .... .... 183
ix
Panhandle Ecological Characterization
Chapter 7 Estuarine and Marine Habitats (continued) Page
d. Vascular plants present .................................... ..... ...................183
e. Nonvascular (and microbial) plant community .......................................... 185
f. Marsh-associated fauna .......................................................................... 186
g. Species of special concern ............................................................................... 187
h. Trophic dynamics/interactions ............................................. 187
i. N natural im pacts .......................................................... ....... .............189
j. H um a n im pacts ........................................ ................ ................ ...................189
k C o nc lu sio ns ........................................ ........ ............ ............ ....................19 0
7.2.3 Intertidal Flats
a. Introduction .............................. ........................... ..... 190
b F lo ra ..................................... .......... .. .... .......... .. ...... ..... ...... .............19 0
c. Faunal composition ....................................... ............ .............................. 190
d. Trophic dynamics and interactions .................................................................... 191
7.2.4 Hard Substrates
a. Introduction ................. ......................................................................... . 193
b. C om m unity structure .........................................................................................193
c. Trophic dynamics and interactions ................................................... .................193
7.2.5 Oyster Reefs
a Introd uctio n .............................................. .... ......... .................. . ....... 193
b D istnb u tio n ................................................................ .................. .................1 9 4
c. Oyster autecology ......................................................................................195
d. Oyster reet development and zonation ....... ........................... ...................196
e. A associated fauna ...... .......... ............................. ... .......... ................. 196
f. Commercial aspects ............................ ......... .......... 197
g. N natural im pacts ................................... ..... ..... ............. .........................198
h. H um an im pacts .......................................... ..............................................199
i. C conclusions .................................................. .. ....... .......................... . 200
72 6 Marine Algae
a Intro d u ctio n ............................ .... .. .. ............... ........... ..................... 2 00
b. Major algal species present................................. .......................................200
c. A associated fauna .......................................... ..............................................200
7.2.7 Open Water
a. Introduction ............................... ........ ............. ..... .............................200
b. Species present .................... ....................................................................202
c. Recreationally and commercially important species .........................................202
d. Species of special concern............................................................................206
e. N natural im pacts ............................................. ............. ..... ...........................206
f. Human impacts .................................... .................................................206
7.2.8 Subtidal Soft Bottoms
a Introd u ctio n ........................................................................... ........................2 0 6
b. P physical distribution ........ .... ................... ........................ .......................207
c D istrib utio n ........................................ ..... ..... .......................... .. ............2 0 7
d. Faunal com position .............................................................. ...................... 207
e. Recreationally and commercially important species ........................................ 209
f. Trophic dynamics and interactions ...............................................210
g. N natural im pacts ........ ............................ ............................... .. ......... ..210
h. Human impacts ...................................... .. ..................211
Contents
Chapter 7 Estuarine and Marine Habitats (continued) Page
7.2.9 Seagrass Beds
a Introductio n ...2...........11.......... ........ .. ......................................2 11
b. Seagrass species present ....................... ..................................... ..........213
c. S easonality ................................................................ ......... ......................2 13
d. Species succession ........................................... ........................ ....213
e. Distribution "-
f. Associated flora and fauna .................. ............. ... ............................ ....... 221
g. Trophic dynamics and interactions ....................... .......................... .... 222
h. Commercially important species .. .. .................................. ...............224
i. N natural im pacts ............................................... ............................................224
j. Hum an im pacts .................................................. .......................... ... ....224
7.2.10 Subtidal Leaf Litter
a. Introduction ......... ...... ........ ............. .. ... 225
b. Associated fauna and flora ............................... ............. ...... ........ 226
c. Trophic dynamics and interactions .......................................................226
d. N natural im pacts ....... ....... .............. ..................................... ...................226
e. H um an im pacts ... ............ ....... .................. ........................................ 226
7.3 Marine Habitats
7.3.1 Hard Substrates
a. Introduction ................................ ...... ... ........ ........ ................ 227
b. Associated flora and fauna .................................... ...............227
7.3.2 Sandy Beaches
a. Introduction ............. ....... ................. ..... ...................... .........228
b. Beach donation ............. ................................ ....................... .......... 228
c. A associated fauna ........... ......... ........ ....... .............. ...... 228
d. Species of special concern .......... ... .................... .... .................229
e. Trophic dynamics and interactions ......... ...................................... ........ 229
f. N natural im pacts ............ .................................... ..........................................2 30
g. Hum an im pacts ....................................................... ..... ... .... .....2. 30
7.3.3 Manne Open Water
a Introductio n .............. ........ ........... ............. .... ........... .......... 23 1
b. Species present... ....................................... ..... ... ....................231
c. Recreationally and commercially important species ........................ .... ......231
d. Species of special concern ................ ............. ..................... .........234
e N natural im pacts .................. ...................... ..... ..........................................234
f. H um an im pacts .................... .. ... ..... ......... ............................ 235
7.3.4 Artificial Reefs
a Intro d u ctio n .............. ........ .. ......... .. .. ... .. .. ... ... .... .... ........ .. 2 3 5
b D istributio n ............. ........... ........... .............. ........ ......... ........ ....... 23 6
c. Associated fauna .......... ............... ........ .............. .. .... .... ........ 236
d. Trophic dynamics and interactions ........................... ..... ..............238
7.3.5 Subtidal Rocky Outcroppings/Natural Reefs
a Intro d u ctio n ... .... .... ... . .. ............. ...... ....... ... .. .... ....... .. ............ 2 3 8
b. Associated flora and fauna .................... ..................... ............ .............239
7.3.6 Subtidal Soft Bottoms
a In tro d u ctio n .................................. ..... .... .... ........... .. ..... ........... .. 2 3 9
b. Physical description .... .......... .. .... ........ ... ......239
c F a u na p re se nt ..................................................... .............................. ........ 2 39
d. Trophic dynamics and interactions .......................... .......................241
e. Natural im pacts ... ... ............................................. ........... .............241
f. Hum an im pacts ...................... ... .. .. ... ........ .......... ..............241
Panhandle Ecological Characterization
Chapter 8 Summary
8.1 The Panhandle in Review ........ .. .................... .... ............ ....242
8.2 Panhandle Findings ................. ....................... ......... ..... ... 243
8.3 The Panhandle Tom orrow .......................................................... ................................ 246
LIT E R A T U R E C IT E D ........................................................................ ............................... 249
APPENDIXES
A. Federal, State, and Local Environmental Control Agencies and Their
R responsibilities ............ .. ..... ... ... .. . ........ ......... ... .. 275
B. Panhandle Regulatory Agency Locations and Addresses ................ .......277
FIGURES
Page
Chapter 1. Introduction
1. Florida Panhandle drainage basins and features. ............. .....................2..
Chapter 2. Geology
2. Terraces in the Florida Panhandle formed by previous sea-level stands .....................................4
3. M ajor structural features of the Florida Panhandle ................................................... .. .......... ....5
4. Surface geology of the Florida Panhandle .................................................................. ................7
5. Physiography of the Florida Panhandle ............................. .......................................... ............... 15
6. The thickness of Eocene to Recent sediments along the Panhandle coast from
Choctawhatchee Bay to the Alabama-Florida border........ ......................................... ........ 20
7. Coastal energy levels and tidal ranges for the northeastern Gulf of Mexico ..............................21
8. Schematic of net littoral drift along "idealized" Panhandle coast ........................................ ....21
9. Nearshore bottom topography off Choctawhatchee Bay showing sand body features ................22
10. Stratigraphy of coastal region from Cape San Bias to Ochlockonee Bay........ ................ ....... 23
11. Surface sedim ent com position in St. Joseph Bay........................................ .............................. 25
12. Generalized geologic column of formations in the western portions of the Florida Panhandle ......28
13. OCS leases in the Pensacola and Destin Dome Blocks off shore from west Florida .... 29
Chapter 3. Climate
14. Locations of NOAA climatological stations in the Florida Panhandle .......................... ........ ..30
15. Isotherms for mean maximum and mean minimum July temperatures in Florida Panhandle ........31
16. Isotherms for mean maximum and mean minimum January temperatures in Florida Panhandle .32
17. Seasonal rainfall variation at selected sites in Florida Panhandle ................. ... ....................... 33
18. Panhandle average annual rainfall and NOAA climatological station locations............................34
19. Panhandle maximum and minimum twelve-month rainfall .............. ............ .......................35
20. Percent of total daily rainfall during individual hours of the day at Tallahassee .......... ...... ... 36
21. Occurrence of extended dry periods at Tallahassee and Pensacola, 1950-80 ...........................36
22. Low level (600-900 m) winds ................... .......................................... .... .............. .......37
23. Percentage of time wind blew from different directions in Florida Panhandle during
spring and summer, 1959-79 average. ................. .......................... ................ .... .....38
24. Percentage of time wind blew from different directions in Florida Panhandle during
fall and w inter, 1959-79 average ....................... ............. .............. .. ....... ..... 38
25. Seasonal windspeed at selected sites in Florida Panhandle ....... ... .. ... .... 38
26. Paths of hurricanes striking the Panhandle coast, 1885-1985............. .............................. .. 39
27. Change in length of atmospheric light path with change in distance above or below orbital plane 40
28. Change in light intensity at Earth's surface with change in distance above or below orbital plane 40
29. Mean daytime sky cover and Tallahassee cloud cover from 3 years of satellite data ............... 41
Panhandle Ecological Characterization
Chapter 3. Climate Page
30. Variations in insolation striking the atmosphere depending on latitude and season .................42
31. Monthly insolation at selected sites in Florida Panhandle ............................................................ 43
32. Mean percent of possible sunshine at selected sites in Florida Panhandle ......... ...................43
33. Increasing atmospheric carbon dioxide as measured atop Mauna Loa, Hawaii..........................46
Chapter 4. Hydrology and Water Quality
34. The basic hydrologic cycle. ...................................................... ................................................. ... 49
35. Panhandle drainage basins discussed in this document ......................................... ...... ....50
36. Out-of-State drainage basins of Panhandle rivers .........................................................................51
37. Primary Panhandle aquifers used as water sources ....................................................................52
38. Hydrologic cross sections of the Panhandle ....................................................................... ... 52
39. Potentiometric surface of the Floridan aquifer in the Panhandle in May 1980 ...................53
40. Recharge areas to the Floridan aquifer in the Panhandle ....................................................... 53
41. Oxygen solubility as a function of temperature. ................................................................. 56
42. O xygen solubility as a function of salinity. .................................................................................. .... 56
43. Minimum pH of Panhandle surface waters ........................................ ........................... ....... 58
44. Concentrations of dissolved solids in Panhandle surface waters ......................................... 59
45. Seasonal riverflow in two Florida Panhandle rivers ............................................................... 63
46. Apalachicola River flow and rainfall at City of Apalachicola.........................................................63
47. Locations and magnitudes of major Panhandle springs ...............................................64
48. (A) Formation of a salt wedge and "stacking" of freshwater layer to right of flow direction
at river mouths. (B) Coriolis and geostrophic forces affecting fresh water flowing from river
mouths. ...................................................... .................. 66
49. Generalized relationship of surface water to ground water for springs and siphons. ................ 70
50. Location of limestone aquifers known to be within 50 ft of land surface and of
surficial beds of low w after perm ability ................ ..... ...... .... .... .......... .........................73
51. Seasonal fluctuations in air temperature at Tallahassee and Sanford Fire Tower and in
water temperature of Sopchoppy River, June 1964 to September 1968...................................75
52. Potentiometric surface of the Floridan aquifer in 1940 and 1980, before and after
increased ground-water pumping in the area of western Choctawhatchee Bay .....................80
53. Eastern Panhandle drainage basins-Ochlockonee River, Coastal area between
Ochlockonee River and Apalachicola River, Apalachicola River, and Chipola River ..................81
54. East-central Panhandle drainage basins-St. Andrew Bay and Choctawhatchee River ...............93
55. West-central Panhandle drainage basins-Choctawhatchee Bay and Yellow River .....................97
56. West Panhandle drainage basins-Blackwater River, Escambia River and Escambia Bay ........100
57. Projected sea-level rise using different scenarios .......................................... .106
58. Diagram showing Bruun Rule for beach erosion following increase in sea level.........................106
Chapter 5. Terrestrial Habitats
59. Vegetative communities of the Florida Panhandle ........................ ... .. ...................... 11
60. Stream habitat classification ............................................ ..... .. ..... ............................... 123
61. Distribution of known steepheads in the Florida Panhandle .....................................................125
62. Pine-hardwood continuum developed over a steep slope/moisture gradient ............................128
Chapter 6. Freshwater Habitats
63. Flatwoods seepage bog developed along a gentle slope/moisture gradient ..............................148
64. Flatwoods savannah, a special case of a seepage bog that is underlain by silt and having a
nearly level slope ............. ... .... .. ..... .. ... .. .. ... ........ .. ... .. .. .. ....................... 149
Figures
Chapter 6. Freshwater Habitats (continued) Page
65. Relative leaf productivity per stem biomass of 11 major leaf-fall producers (trees) in the
Apalachicola River flood plain .... ................... ................... ............................. .................... 158
66. Mean monthly leaf fall of three representative species of intensive-transect plots.......... ..........159
67. Decline in carbon, phosphorus, nitrogen, and total leaf mass during decomposition in
Apalachicola R iver system ......................... ............................................................................ 160
68. Distribution of caves and phreatobites in Panhandle Florida..................................................... 173
69. Regional structure of eastern Panhandle Florida showing the Gulf Trough putative barrier
to dispersal between the Chattahoochee and Woodville phreatobite faunas..........................174
Chapter 7. Estuarine, Saltwater Marsh, and Marine Habitats
70. Schematic views of gulf coast salt marshes on protected low-energy shorelines and
open moderate energy shorelines ............................................................... .... ..... .....184
71. Horizontal distribution of macrofauna in a typical Panhandle tidal marsh ..................................186
72. A cross-sectional view through a typical intertidal sand-flat community in the Panhandle
show ing representative invertebrates .............................................................. .............. ........191
73. Seasonal stone crab densities on a Panhandle oyster reef ....................................................... 198
74. Stone crab age-group occurrence on a Panhandle oyster reef ...................................................198
75. Seasonal variation of the spionid polychaete Prionospio pygmaea in a St. George Sound
subtidal soft-bottom habitat .............. ..................... ................................................................ 209
76. Variation in a five-slotted sand dollar (Mellita quinquiesperforata) population from
St. G eorge S found ....... ........... ....... ........ .. .. ... .............................. .... .. .................. 210
77. Yield of penaeid shrimp and vegetation coverage in an estuary .................................................212
78. Four common seagrass species present in Panhandle waters .............................................. 214
79 Diagram of a typical Thalassia shoot ............................... .. ... ....................................... .. 215
80. Diagram showing typical depth distributions of three seagrass species and a common
brackish species Ruppla m aritim a ...................................................................................216
81. Ecosystem develop ent in seagrasses ............... ...................... ............................... .............217
82. Idealized sequence of seagrass recolonization and growth after a large disturbance ...............217
83. Seagrass distribution in St. Joseph Bay in 1981 ......... .............................................................219
84. Seagrass distribution in a portion of the Pensacola Bay system .............. ................................220
85. Schematic view showing the numerous seagrass epiphyte interactions that occur in a
seagrass bed and the important physical factors affecting the interactions ............................223
86. Seasonal abundances of leaf-litter associated invertebrates from the Apalachicola Bay
system in 1976 ............ .... ................... .. .. .. .. .............. .. ........................ ..................226
87. A high-energy beach community, showing major zones relating to sand motion ......................228
88 Change in Panama City beach profile after Hurricane Eloise in September 1975 ..................... 230
89. Seasonal phytoplankton abundances in the northeast Gulf of Mexico ........................................232
90 Correlation of pelagic fisheries to changes in air temperatures off Panama City ......................233
91 Artificial reef locations in Panhandle waters .. ........................................................... ........ 237
92. Cross-sectional view through a typical rocky outcropping off the Panhandle coast ... ...........240
Chapter 8. Summary
93. 1980 Florida Panhandle population distribution ........................................... ................ ...............244
94. 1980 Florida Panhandle population density and projected population increase 1980-2000........247
TABLES
Page
Chapter 3. Climate
1. Panhandle thunderstorm frequency statistics.................................................... .........................36
2. Total number of hurricanes striking the Florida Panhandle during 1885-1985 ............................. 40
Chapter 4. Hydrology and Water Quality
3. Drainage basin statistics for major Florida Panhandle ........................... ......... 74
4. U.S. Geological Survey maps for the Florida Panhandle ............................................................... 77
5. Scenarios of future sea-level rise ................................................ .................... .....................105
Chapter 5. Terrestrial Habitats
6. Endangered and threatened plants of Panhandle Florida and counties where they are found...... 112
7. Endangered and threatened vertebrate animals of Panhandle Florida ........................................114
8. Numbers of amphibians and reptiles captured on two annually burned pine stands and an
unburned hardwood stand in north Florida ............................................................................ 119
9. Breeding birds of clayhill longleaf pine old-growth forest .......................................................... 120
10. Species of trees in the beech-magnolia forest association in the Panhandle ..............................130
11. Comparison of floral diversity among four flatwoods sites in Panhandle Florida ...........................134
Chapter 6. Freshwater Habitats
12. Types, species composition, and distinguishing characteristics for bottomland hardwood
forests of the Apalachicola River .................................................................................................155
13. Species abundance for all forest types combined ..................................................................... 157
14. Common macrophytes of Lake Seminole ................................................................................ 176
Chapter 7. Estuarine, Saltwater Wetland, and Marine Habitats
15. Definition of the estuarine and marine systems ............................................ ............................................. 179
16. Common benthic macroinvertebrates found in brackish vegetation in the Panhandle................... 181
17. Common vascular plants present in Panhandle salt marshes.............................................182
18. Zonal relationship of algae with spermatophyte community in Panhandle marshes ....................185
19. Common invertebrates of Panhandle salt marshes..................................................................186
20. Common fishes of Panhandle salt marshes ..... ......... ... ..................... ............ .......187
21. Common reptiles of Panhandle salt marshes ...................................................................... 187
22. Common birds of Panhandle salt marshes ...................................................................... ......188
23. Common mammals of Panhandle salt marshes...........................................................189
24. Commonly encountered macroinvertebrates of Panhandle intertidal flats ..............................192
25. Common birds of Panhandle intertidal flats ..................................... .. .. 192
26. Common decapods found on Panhandle jetties............................................................ .... ....... 194
27. Area of oyster reefs (beds) in the Florida Panhandle .............................................194
Tables
Chapter 7. Estuarine and Marine Habitats (continued) Page
28. Com m on fauna of a Panhandle oyster reef ....................... .... .. ...............................................197
29. Oyster landings from Choctawhatchee Bay,1965-82 ................................ .................... 198
30. Com mon algal species in the Panhandle .................... ...................................................... ....201
31. Common planktonic organisms found in Panhandle estuarine open waters... ............................. 203
32. Common nektonic forms found in Panhandle estuarine open waters ................. ........................204
33. Demersal fish, skates, and rays commonly encountered in Panhandle soft-bottom habitats ........207
34. Abundant or common benthic meiofauna in Panhandle soft-bottom habitats ................................208
35. Abundant or common benthic macroinvertebrates in Panhandle soft-bottom habitats ................208
36. Surface area of major water bodies and most recent seagrass distribution estimates for the
Panhandle w ater bodies .............. ........... ... ..................................................................... 218
37. Dominant epiphytic organisms that grow on seagrass blades .....................................................221
38. Dominant mobile fauna within the seagrass leaf canopy ............................................................222
39. Dominant epibenthic and infaunal invertebrates that live on or within the sediments of
seagrass m eadow s ....................... ...................... ............................................................. . ...... 222
40. Common fauna of Panhandle leaf litter habitats ........................................ ............... ...............226
41. Common macroinvertebrates present on Panhandle beaches ............................................. 229
42. Common seabirds and shorebirds present along Panhandle beaches................................ ..... .229
43. Common plankton present in the marine open-water habitat of the Panhandle ..........................231
44. Common fish species present in marine open waters of the Panhandle ....................................232
45. Marine turtles with special status that occur in Panhandle marine waters ...................................233
46. Charter and party boat principal ports of call .................................................................... ...................233
47. Shipw recks in Florida Panhandle w aters.......................................................... ........................ 238
48. Some resident reef fish from eight artificial reefs off Panama City, Florida.................................238
49. Common invertebrates present in nearshore soft-bottom habitats in the Panhandle...................241
ACRONYMS
State and Federal agencies and programs
A-C-F Apalachicola-Chipola-Flint Rivers
ANF Apalachicola National Forest
FDA U.S. Food and Drug Administration
FDER Florida Department of Environmental Regulation
FDNR Florida Department of Natural Resources
FNAI Florida Natural Areas Inventory
FREAC Florida Resources and Environmental Analysis Center
HRS Florida Department of Health and Rehabilitative Services
IFAS Institute for Food and Agricultural Service, University of Florida
NMFS National Marine Fisheries Service
NOAA National Oceanic and Atmospheric Administration
NPDES National Pollution Discharge Elimination System
NWFWMD Northwest Florida Water Management District
OCS Outer Continental Shelf
OFW Outstanding Florida Water
SR State Route
USACE United States Army Corps of Engineers
USFWS United States Fish and Wildlife Service
USGS United States Geological Survey
xviii
ACKNOWLEDGMENTS
The authors wish to thank the following persons for their contributions: Carol Knox,
Elizabeth Woodsmall, Steve Bradley, graphics; Lorna Sicarello, U.S. Fish and Wildlife
Service, review and documents; the staffs of the Northwest Florida Water Management
District, the Environmental Protection Agency's Gulf Breeze Laboratory, and the National
Marine Fisheries Service's Southeast Fisheries Center (including Librarian Rosalie Vaught
and Director Eugene L. Nakamura); Jim Muller, Florida Natural Areas Inventory, marine
and estuarine habitat information; Henry Bittaker, seagrass information; Dr. Richard
Iverson, prepublication seagrass manuscript; Kevin Sherman, review and meiofaunal
information; Dr. Landon Ross and Craig Dye, Florida Department of Environmental
Regulation, and Loretta Wolfe, Wolfe Associates, reviews.
We owe a special thanks to Dr. Millicent Quammen of the U.S. Fish and Wildlife Service's
National Wetlands Research Center for coordinating the reviews and for general
assistance and patience far beyond that which is reasonable. We also acknowledge
Center employee Dana Criswell for editing.
Grateful appreciation is extended to the Minerals Management Service's Gulf of Mexico
OCS Regional Office for their participation in planning this project and for providing funding
to print this document. Dr. Robert Rogers served as Contracting Officer's Technical
Representative for the project. Janice Blake, Debbie Miller, and Mike Dorner of that office
contributed significantly in coordinating publication.
Chapter 1. INTRODUCTION
1.1 Purpose and Organization
The Florida Panhandle is one of the most rapidly
developing regions in the entire State. Coastal cities
such as Panama City, Destin, and Pensacola, with
their attractive white-sand beaches and clear wa-
ters, are the centers of this growth. Concomitantwith
such growth are rapid alterations in surrounding
terrestrial and aquatic habitats caused by increased
urbanization, industrialization, sewage and effluent
discharge, river flow alteration, stormwater runoff,
and dredge and fill activities.
Many Panhandle commercial interests, espe-
ciallyfishing and tourism, are highly dependent upon
the maintenance of relatively unaltered habitats.
The residents of many small Panhandle coastal
communities such as Apalachicola and Carabelle
derive practically all their incomes from the seafood
industry. If unregulated growth occurs without re-
gard to environmental impacts, the failure of this
economy and the end of a unique way of life may
follow. In addition, the destruction of the natural
coastal setting would seriously curtail tourism.
Critical decisions on the preservation or econo-
mic development of particular areas are often made
without knowledge of the composition, dynamics,
and sensitivity of the local habitats and the associat-
ed flora and fauna to perturbations. Additionally,
higher level interactions between systems and habi-
tats are often overlooked. This report is an extensive
review and synthesis of available literature on the
local physical setting and ecology and a discussion
of important impacts on the habitats within the Pan-
handle region. We have attempted to project pos-
sible future impacts and to point out areas that need
further research before they are permanently al-
tered.
The report is divided into two main sections.
Chapters 2, 3, and 4 cover the geology and physio-
graphy, the climate, and the many aspects of the
surface- and ground-water systems. These chap-
ters provide the physical and chemical background
information necessary to understand many of the
environmental pressures affecting the biological
habitats. These habitats-terrestrial, freshwater,
estuarine, and marine-and their inhabitants are
described in Chapters 5, ,6 and 7. Chapter 8 is a
summary of the Panhandle systems and a discus-
sion of their unique aspects as well as of areas that
are in need of further investigation.
1.2 The Florida Panhandle: Overview
The Florida Panhandle discussed in this report
(Figure 1) extends from the Ochlockonee River
basin west to the Florida Alabama border (not in-
cluding Perdido River basin and Bay) a Band north to
the Georgia and Alabama borders. Major rivers in
the region include the Ochlockonee, Apalachicola,
Chipola, Choctawhatchee, Yellow, Blackwater, and
Escambia. Major bays and estuarine systems in-
clude: Ochlockonee Bay, Apalachicola Bay, St.
Joseph Bay, St. Andrew Bay, Choctawhatchee Bay,
and Pensacola Bay. Also discussed are the
nearshore Gulf of Mexico waters and the adjacent
Continental Shelf region
The Panhandle contains a wide variety of sur-
face waters and physiographic regions. This lends
it an ecological diversity found in few other areas in
the United States. The Panhandle also boasts
several of the largest and most productive estuaries
inthe State. Localfisheries andthe fisheries of much
of the coastal area depend on the water quality of
these estuaries for spawning and nursery grounds.
Their protection must be of high priority. Many inland
Panhandle Ecological Characterization
87' 86' 65. 840
ALABAMA
/ j j -7 -- /'~ 'iV D
/I J
0 10 20 30 40 50
S I MMiles
A. Ochlockonee River
B. Coastal area between Ochlockonee
and Apalachicola Rivers
C. Apalachicola River
D. Chipola River
E St. Andrew Bay
F. Choctawhatchee River
G Choclawhatchee Bay
7 )
/ JEFFERSON
H Yellow River
J. Blackwater River
K. Escambia River
L. Escambia Bay
Figure 1. Florida Panhandle drainage basins and features.
areas are undeveloped and probably will remain so
in the near future. Other areas, most notably the
western coasts, are undergoing explosive growth
very similar to that occurring in the southern part of
the State. Unfortunately, this growth is often taking
place with no more regard given to habitat destruc-
tion and environmental impact than is given in the
south. We hope this document will help produce
wise decisions concerning the direction and meth-
ods of Panhandle growth.
GULF OF MEXICO
Chapter 2. GEOLOGY AND PHYSIOGRAPHY
2.1 Introduction
The animals and plants of any region are great-
ly affected by its geology. Plants are rooted in soils
derived from the inorganic rocks or sediments of the
earth's surface and are further affected by the slope,
moisture-bearing content, chemistry, and physical
nature of the sediments. Animals, in turn, are af-
fected by plants as food and shelter. Animals may
also respond directly to the geology of a region
because they live on the soil surface or burrow in it.
The slope, friability, moisture-bearing capacity, and
other properties of soils often have as much influ-
ence on animals as on plants.
The surface geology of Panhandle Florida is
entirely sedimentary, comprised of three different
types of sediment: limestones, organic, and clas-
tics (silt, clay, sand, gravel). The northern half of the
Panhandle is dominated by sandy clays or clayey
sands deposited by the alluvial action of rivers and
streams. The southern half of the Panhandle, espe-
cially in the west, is dominated by sands deposited
along ancient shorelines. The surface of the ground
in the eastern half of the Panhandle and in the vicinity
of Marianna, Jackson County, is influenced by the
presence of limestones near the surface which have
caused the top of the ground to be modified topogra-
phically by various types of subterranean solution
activity. In low lying areas (stream courses or natural
depressions of varying kinds), especially south of
Cody Scarp and east of the Choctawhatchee River,
peat, muck, and other types of decomposing plant
litter are very common.
Panhandle Florida has been slowly emerging
fromthe sea since at least some time in the Miocene.
The age of surface sediments, therefore, is older
near the Alabama and Georgia borders and be-
comes progressively younger towards present sea
level. The floor of each stand of the sea was a
relatively flat, gently seaward-sloping terrace when
first exposed by the receding shoreline. Terraces
are separated from each other by step-like escarp-
ments orby subtle changes in relief (Figure 2). Since
their emergence, terraces have been eroded and
dissected by streams and rivers. Entire strata have
been removed in some areas, and materials from
other strata have been deposited on top of lower
terraces, and rearranged by the erosive power of
water.
Fifty-two percent of the open gulf beaches from
Mexico Beach to a point due south of Tallahassee
have been eroding during historical times (Tanner
1975). In the same time period, 35% have been
stable, and only 14% have been growing. An as-
tounding 11.2 m per year of beach front has eroded
from Cape San Bias between the years 1875 and
1942. Dog Island has been eroding at about 1 m per
year, and St. George Island has been lengthening its
eastern tip at a rate of about 20 m per year, but the
beach face has been eroding at about 1.3 m per year
between 1934 and 1970. Given the consensus of
scientific researchers that sea level has been rising
overthe past century and that a greenhouse effect is
now measurable due to increased CO, levels from
fossil fuel combustion and other human activities, it
seems certain that sea level will continue to rise over
the next century. Some geologists have calculated
that if all the ice in polar regions and montane
glaciers were to melt, the ocean surface would rise
at least 100 ft. This is close to the topof the Wicomico
terrace, presumably the shoreline at the end of the
Pliocene and at the onset of the Pleistocene. The
land submerged under the Wicomico sea (Figure 2)
indicates that about one-half of the surface of the
Panhandle would be inundated in this scenario.
S
Terrace elevations 0
215- 320ft Includes Hazlehurstterrace(for-
merly Brandywine) (Cooke 1939), Coast- 42-70 ft Penholoway terrace
wise delta plain (Vernon 1942), and part of
High plocene terrace (Macneil 1949)-
170-215 It Cohane terrace 25-42 It Talbot terrace
100 170 It Includes Sunderland terrace
(Cooke 1 39). Okeenokee terrace (Mac 8-25 ft Pamlico terrace
Neil 1949)
70-100 ft Wicomico terrace <1-10 ft Silver Bluff terrace
Figure 2. Terraces in the Florida Panhandle formed by previous sea-level stands (after Healy 1975a).
2. Geology and Physiography
2.2 Structure and Geologic Setting
Three structural features dominate the geology
of Panhandle Florida. These are the Gulf of Mexico
Sedimentary Basin, Chattahoochee Anticline, and
the Apalachicola Embayment. The Panhandle from
about Okaloosa County westward is the eastern
edge of the Gulf of Mexico sedimentary basin, a
negative structural feature (i.e., a depression that
receives sediments) whose sediments thicken west-
ward toward the Mississippi River. A positive struc-
tural feature (a rise, from which sediments erode)
called the Chattahoochee Anticline lies at the east-
ern end of the negative area, separating it from a
smaller negative feature called the Apalachicola
Embayment (Figure 3).
The Chattahoochee Anticline is aligned south-
west to northeast across the northeastern portion of
Panhandle Florida (Figure 3), and is very important
to the ecology of the region because it brings Oligo-
cene and Eocene carbonate rocks to the ground
surface where the physical and chemical properties
of the soil and water are greatly affected by the
presence of the carbonates.
The Apalachicola Embayment and its probable
northeastward extension, the Gulf Trough, is a nega-
tive structural feature that represents a downfallen
block of land, called a graben (Schmidt 1984). This
negative feature is important to the biology of the
Panhandle because it is strongly affected by the
predominantly plastic sediments. Clastics differ
greatly from carbonates in their chemistry, physical
properties, and weathering.
The Apalachicola Embayment (Figure 3) is a
relatively shallow basin between the Ocala and
Chattahoochee uplifts, narrowest on the northeast
and opening up to the south and southwest. The
magnitude ofthebasin increaseswith depth, indicat-
ing that it is a long-developing feature. Near the
ground surface the Quaternary and Neogene rocks
are gently downwarped, but the deeper Paleogene
and Mesozoic rocks are downwarped even more,
resulting in older strata that are thicker (Murray
1961). Southward along its axis, the uppersedimen-
tary rocks (Triassic to Recent) of the Apalachicola
Embayment plunge to a depth of nearly 15,000 ft
before metamorphic Paleozoic rocks are encoun-
tered (Applegate et al. 1978). At the eastern limits of
CHATTOAOON'CE 0* 20MILES
ANTICLINE 0 16 32 KILOMETERS
G- LF OF MEXICO,
SEDI METAIRY /
B.SI.. APALACHICO L A
FLORIDA
PENINSULA SEDIMENTARY
PROVINCE\
NORTH GULF COAST
SEDIMENTARY PROVINCE
Figure 3. Major structural features of the Florida Panhandle (from
Schmldt 1984).
Panhandle Ecological Characterization
the Apalachicola Embayment, carbonate sediments
rise and are exposed at the ground surface begin-
ning at the eastern edge of Panhandle Florida and
cresting along the Ocala Arch of the Florida Penin-
sula Sedimentary Province in the very northwestern
part of peninsular Florida (the Big Bend region).
The western Panhandle from about the Choc-
tawhatchee River westward is underlain by west-
wardly thickening plastic sediments variously bed-
ded as sands, clays, shales, sandstones, and thin
limestones. The hard limestones of the central and
eastern Panhandle either pinch out or dip deeply
west of the Choctawhatchee River and have little or
no surface expression on the landform.
The surface sediments of the northern half of the
Panhandle west of the Choctawhatchee River are
crossbedded sands, gravels, and clays called the
Citronelle Formation. These are Pliocene to Recent
fluvial deposits that are commonly found at eleva-
tions above 200 ft. Tan to light-orange clayey sand
is found southward towards the coast in the western
Panhandle, and probably represents the reworking
of some of the higher Citronelle hills during sea level
fluctuations. These clayey sands grade into uncon-
solidated white to light-gray quartz sands of the
Pleistocene to Recent coastal terraces. The terrace
deposits generally thicken from zero to nearly 100 ft
near the coast.
The eastern Panhandle isan uneven platform of
carbonate bedrock over which has been deposited
one or more layers of less consolidated clastics. The
bedrock consists mainly of limestone (calcium car-
bonate) and sometimes of dolomite (calcium car-
bonate with varying percentages of magnesiumcar-
bonate). Impurities of sand, silt, and clay increase in
the limestones going east. Other limestone has
been silicified into layers or veins of chert orflint. The
superficial strata of bedrock date to the Eocene,
Oligocene, and early Miocene (Figure 4). The bed-
rock of the eastern Panhandle has been subjected to
considerable solution activity, forming numerous
caverns, lime sinks, and other karst features.
The clastics consist of sand, silt, clay, shell marl,
gravel, rock fragments, phosphate pebbles, and
diatomaceous earths. Fossils, including petrified
wood, are present in some deposits but absent in
others. Sand, silt, and clay are mineral particles
defined by their specific diameters.
Layers of shells and their degradation products
are often common. Clastics with shell marl are
mostlythoughtto representthe sediments of shallow
seas and estuaries. These sediments became ter-
restrial clastics when sea level dropped. The abun-
dance of oyster shells in many shell marls suggests
that oyster bars in bays and lagoons were often
covered by sediments that later became terrestrial
clastics.
Diatomaceous earth consists largely of the sili-
cified walls of diatoms that accumulated in marine
sediments. Such deposits are also known as pipe
clay, fuller's earth, and attapulgite. Thick beds are
mined commercially in Gadsden County for the
production of abrasives and otherproducts. Veins of
diatomaceous earth shrink and swell considerably
with changes in moisture. This movement requires
special foundations for structures built on terrain
containing fuller's earth.
Deposition of the various strata of plastics began
in the Miocene after the carbonate bedrock had
formed. Some of these clastics were once marine
sediments of nearshore environments, exposed
when the Panhandle was uplifted geologically; oth
ers were deposited as alluvium in valleys or as
deltaic or estuarine deposits near river mouths.
Otherswere wind-blowndeposits such asdunes and
still others were sediments in lake bottoms.
The plastic deposits form terraces that slope
gently towards the Gulf of Mexico and which are
separated from each other either by step-like es-
carpmentsorbysubtlerchanges in relief. Sincetheir
deposition the terraces have been subjected to
considerable erosion and dissection by streams and
rivers. Entire strata have been removed from some
areas, and the materials of other strata have been
reworked by erosional processes.
Peat deposits are common. Peat consists of
dead plant matterwhich maypersist forthousandsof
years or longer without appreciable decomposition.
Peats build up in marshes, swamps, and lake bot-
toms, wherever low oxygen conditions prevail, inhib-
iting organisms of decay. High acidity and low levels
87*
----1
86o Bas 84'
1 1 1
ALABAMA
GECRGIA
cc
JEFFE
QD
V
,- .........-.:.-.......... uI- F.,:..-.... -..... \" ;;- -
Miocene Ctronelle Formation [ Holocene undifferentiated
Pliocene Jackson Bluff Formation
Figure 4. Surface geology of the Florida Panhandle (after Purl and Vernon 1964, Brooks 1981a).
-4
Panhandle Ecological Characterization
of nitrogen may reinforce this inhibition. The oldest
peat occurs at the bottom of a deposit, and new peat
forms at the surface as dead plant materials accu-
mulate. Other, nonfibrous peat is generally called
muck. Most peats contain some sand, silt, or clay
that was transported by water or wind from other
areas. Well preserved wood commonly occurs in
peat. Florida peat deposits and associated vegeta-
tion were surveyed by Harper (1910) and Davis
(1946).
2.3 Stratigraphy
The rocks that underlie the Panhandle range in
age from late Precambrian to Recent. The oldest
rock exposed in the Panhandle is Eocene limestone
of the Crystal River Formation. It is found near the
surface of the ground in northern Holmes and north-
ern Jackson Counties, and is exposed along the
upper Chipola River and upper Holmes and Wrights
creeks. The rocks of different age that are out-
cropped in Panhandle Florida are shown in Figure 4.
2.3.1 Igneous and Paleozoic Rocks
The igneous rocks of Florida include metaba-
salts in Volusia County, granites in Lake and Orange
Counties, granite and diorite in St. Lucie County, and
metabasalt in Hillsborough County (Grasty and
Wilson 1967, Bass, 1969, Milton and Grasty 1969,
Milton 1972, Barnett 1975). Panhandle deep wells
have intercepted granite at 12,191 ft in Bay County,
dacite porphyry and granodiorite in Gulf County at
13,000 ft, and granite at 14,480 ft below the surface
In southern Walton County (Barnett 1975).
The Paleozoic sediments from deep wells in
Florida have been described and correlated by
Applin (1951), Bridge and Berdan (1952), Cramer
(1971), and Barnett (1975). Strata range in age from
late Precambrian to Early Devonian based on fossil
evidence.
2.3.2 Mesozoic Era
Descriptions of the Mesozoic rocks in the Pan-
handle have been reported by Arden (1974) and
Applegate et al. (1978). Overlying the Paleozoic
igneous rocks is the Eagle Mills Formation of the
Triassic Age. This formation contains dikes and sills
of basic igneous rocks. Its overall lithology has been
described by Applegate et al. (1978) as well-indu-
rated, highly micaceous sandstones; argillaceous
siltstones; and well-indurated shales.
In the eastern part of Bay County, the Eagle Mills
Formation is probably absent, thinning from about
200 ft in western Bay County. The Norphlet,
Smackover and Haynesville Formations are found
here, overlying the basal granite. These formations
are all UpperJurassic in age. The Norphlet is 267 ft
thick and consists of red sandstones, siltstones, and
shales. The Smackover Formation is 163 ft thick and
is composed of limestone and dolomitic limestones.
The Smackover Formation was found to have oil
locked in a dense impermeable section of limestone
and conglomeritic calcareous sandstone. The next
younger formation, the Haynesville, is just over 300
ft thick and is composed of red to gray, very well
indurated calcareous shales, a few well sorted fine-
grained sandstones, and a fewthin-bedded micrites.
All three formations apparently thin westward
because only a thin Haynesville section is present in
a deep well drilled in western Bay County. West of
Bay County these units thicken as they plunge into
the Mississippi Embayment. In Bay County, the
Eagle Mills Formation is overlain by 2,600 ft of the
Cotton Valley Group sediments. This group also
overlies the Haynesville section in eastern Bay
County (Schmidt and Clark 1980). The Cotton
Valley Group is Upper Jurassic in age and is a vari-
colored mudstone and coarse sandstone.
Above the Cotton Valley sediments are differen-
tiated Lower Cretaceous sands and shales, varying
from 5,000 to 6,000 ft in thickness. Above these lie
the white sands of the Lower Tuscaloosa Formation,
which is Upper Cretaceous in age.
The Tuscaloosa Formation consists of non-
marine, gray to green, fine to coarse, poorly sorted
sand and variegated shales underlying a marine
member consisting of a gray laminated micaceous
glauconitic hard shale with shell fragments and car-
bonaceous seams and flecks. On top of this, the
Tuscaloosa Formation consists of a gray to cream
fine calcareous micaceous clayey silty sandstone
with beds of calcareous shale. The thickness of the
Tuscaloosa Formation varies but has been reported
to be over 700 ft thick (Puri and Vernon 1964).
2. Geology and Physiography
Overlying the Tuscaloosa Formation in Panhan-
dle Florida is the Eutaw Formation: gray to cream
calcareous fine sandstone that changed downdip
into a soft pasty sandy chalk with limestone seams.
It ranges between 150 and 300 ft in thickness.
Above the Eutaw are sediments of the Austin
Age. These beds are equivalent to the Mooreville
Chalk in Alabama. In northwest Florida, these sedi-
ments are gray soft glauconitic micaceous fine-to-
coarse quartz sand interbedded with gray-green soft
calcareous thinbedded clay, averaging 350 to 450 ft
thick. Generally less than 500 ft in thickness, beds
of the Taylor Age overlie the Austin Age beds. The
uppermost Cretaceous sediments are beds of the
Navarro Age. The presence of these sediments is
questionable in northwest Florida, but a thin gray
pasty marl occurs at the top of the Taylor beds in the
western Panhandle.
The Mesozoic sediments total approximately
10,000 ft in combined thickness in the vicinity of Bay
County. The first occurrence is generally deeper
than 3,000 ft below sea level, and the sequence
continues downward to about 13,000 ft below sea
level.
2.3.3 Cenozoic Era
In the Florida Panhandle, an unconformity sep-
arates the basal Paleocene sediments from the
Upper Cretaceous rocks (Applin and Applin 1944,
Rainwater 1960). Applin and Applin (1944) have
stated that inthe Tallahassee area, Paleocene strata
lie unconformably on beds of the Taylor Age, with the
Navarro equivalent and upper beds of Taylor Age
being present.
a. Paleocene Series. The Paleocene Series in
Northwest Florida consists of plastic beds of the
Midway Age. The Midway Stage has been divided
into three units in Alabama: the Clayton, Porters
Creek, and Naheola Formations. In the Florida
Panhandle, these formations are undifferentiated,
which led Chen (1965) to treat the entire stage as the
Midway Formation. Lithologically, the formation
consists of dark green-gray micaceous and slightly
glauconitic laminated calcareous shales, with minor
amounts of thinbedded argillaceous and fossilifer-
ous limestones and glauconitic and calcareous
sandstones. The thickness of these sediments var-
ies from 250 to 750 ft throughout the central Pan-
handle.
The Midway Formation underlies the entire Flor-
ida Panhandle and extends widely throughout the
southeastern Coastal Plain. Regionally, the vertical
and lateral changes of lithologic character and the
thickness of the unit are rather great, as demon-
strated by Chen (1965). His isopach-lithofacies
indicate that the plastic sediments, such as glauco-
nitic and arenaceous shale and sandstones, are
more dominant around the Chattahoochee Arch
than elsewhere in the Panhandle. In addition, cal-
careous shale is a major lithologic component that
occurs over most of the Panhandle region except in
the southeastern area (Wakulla and southern Leon
Counties), where limestone is predominant.
b. Eocene Series. The Eocene Series in the
southeastern Gulf Coastal Plain has been divided
into three stages. These stages are the Wilcox
Stage, which is Lower Eocene; the Claiborne Stage,
which is Middle Eocene; and the Jackson Stage,
which is Upper Eocene.
The Wilcox Stage has been divided into three
formations in southern Alabama, where it crops out.
The stratigraphic equivalent of these three sections
(the Nanafalia, Tuscahoma, and Hatchetigbee For-
mations) has been recognized in the Florida Pan-
handle as undifferentiated Wilcox. Chen (1965)
treats the Wilcox Stage in northwest Florida as a
formation.
In the outcrop belt in Alabama to the north of the
study area, the Wilcox Stage has been demon-
strated to be unconformable with both overlying and
underlying rocks. In Florida, however, no distinctive
geologic evidence of unconformable relationships is
recognized. The Wilcox Formation includes marine
and deltaic plastic sediments. These consist of
glauconitic and calcareous sandstone and green-
gray micaceous calcareous glauconitic and silty
shale.
Using regional lithofacies maps, Chen (1965)
shows that the amounts of plastic sediments de-
crease southeastward away from the Panhandle
toward peninsular Florida. His maps also show the
Panhandle Ecological Characterization
Wilcox Formation to vary in thickness from less than
200 ft in the eastern Panhandle to nearly 1,000 ft
southeastward.
The exposed strata of the Claiborne Stage in
southern Alabama have been divided into three
formations which are, in ascending order, the Tal-
lahatta Formation, the Lisbon Formation, and the
Gosport Sand. In the subsurface of northwest Flor-
ida, the sediments become more calcareous and
less readily differentiated into distinct formations
(Toulmin 1955). As a result, the Claibome is divided
into only two formations in the western part of Pan-
handle Florida, the Lisbon Formation at the top and
the Tallahatta Formation below. These formations
are correlative in time of deposition with the Avon
Park Limestone and the Lake City Limestone, re-
spectively, in peninsular Florida.
The Tallahatta Formation in northwest Florida
consists of glauconitic and calcareous sandstone,
green-gray glauconitic arenaceous and calcareous
shale, and glauconitic argillaceous limestone. The
Lisbon Formation is commonly a glauconitic arena-
ceous and fossiliferous limestone with some beds of
calcareous shale. The combined thickness of the
Claiborne near Bay County approaches 800 ft.
The literature pertaining to the Ocala Group is
extensive. Summaries are contained in Vernon
(1942, 1951), Cooke (1945), Puri (1957), and Purl
and Vernon (1964). The Upper Eocene strata in
Florida have been separated by Purl (1957) on the
basis of a detailed biostratigraphic study into three
formations of the Ocala Group, the Inglis, the Willis-
ton, and the Crystal River, in ascending order. In
Panhandle Florida, the Ocala crops out in Jackson
and Holmes Counties, which are located along the
Alabama State line north of Bay County.
In his study on Holmes and Washington Coun-
ties, Vernon (1942) was able to divide the Ocala into
two lithologic faces. The lower facies is typically
developed in southern Alabama; it bears a lower
Jackson fauna, and consists of greenish-gray glau-
conitic sandy limestone. The upper and more typical
facies is exposed in Holmes County, and is de-
scribed by Vernon as a limestone that is light yellow
to white, massive, porous, and often silicified.
The Ocala was described in Jackson County by
Moore (1955). He describes its lithology as a white
to cream colored generally soft granular permeable
fossiliferous pure limestone. Overlying the Ocala,
Moore identifies the Bumpnose Limestone member
of the Crystal River Formation (the youngest and
uppermost formation of the Ocala Group). The
Bumpnose is characterized by soft, white limestones
with Lepidocyclina chaperi(a large flat foraminifera).
The top of the Ocala Group dips between 10 and
15 ft/mi as it approaches Bay County from the north
(Vernon 1942, Schmidt and Coe 1978). In Bay
County, the Ocala is entirely a subsurface unit
(Schmidt and Clark 1980). The three formations into
which Purl (1957) divided the Ocala are not recog-
nizable in Bay County. As a result, the system
devised by Vernon (1942), an upper and lower
facies, is applied in Bay County. The lower facies
consistsof a light orange to white limestonewith high
porosity, both micrite and sparry calcite cement,
crystal and skeletal grain types, small amounts of
glauconite and sand, and abundant fossils. Domi-
nant fossils include foraminifera, mollusks, echi-
noids, bryozoans, and corals. The large foraminifera
are dominated by species of Lepidocyclina, Oper-
culinoides and Asterocyclina. The upper faces is
similar, except that glauconite is rare and chert is
more common.
In the northern part of Bay County, thicknesses
are lessthan 200ft, the Ocala being over300ft below
sealevel. Inthe southern part of Bay County, the top
of the Ocala dips to approximately 800 ft below sea
level and attains a thickness of over 400 ft. The dip
and thickness, therefore, increases in a nearly due-
south direction.
c. Oligocene Series. The Oligocene series
consists of two formations, the Marianna Limestone
and the Suwannee Limestone. Originally named by
Matson and Clapp (1909), the Marianna Limestone
was described as a soft, porous, light-gray to white
limestone at Marianna, Jackson County, Florida.
Marianna Limestone is exposed at the surface of the
ground along a narrow, nearly east-west band
through Marianna, Florida. In Holmes County, the
outcrop beltturns to the north and the strike changes
to northwest-southeast as it crosses the Alabama
state line.
2. Geology and Physiography
From the outcrop area in Holmes and Jackson
Counties, Marianna Limestone dips gently toward
the gulf coast (Vernon 1942; Moore 1955; Schmidt
and Coe 1978) at approximately 11 to 13 ft/mi. Its dip
into southern Bay County is estimated to increase
slightly to perhaps 15 or 16 ft/mi. The thickness is
generally uniform in Jackson, Holmes and
Washington Counties, and probably increases
slightly in Bay County.
The name Suwannee Limestone was first used
by Cooke and Mansfield (1936) to describe expo-
sures of a hard crystalline yellowish limestone visible
on the Suwannee River between Ellaville (Suwan-
nee County) and White Springs (Hamilton County).
Later, Vernon (1942), Cooke (1945), Moore (1955),
and Reves (1961) established the formation's pres-
ence in the Florida Panhandle. The outcrop belt in
the north-central Panhandle parallels that of the
Marianna Limestone. In general, it can be described
as a tan to buff-colored dolomitic and sometimes
clayey limestone. In some areas, the Suwannee is
predominately dolomitic.
d. Miocene and Pliocene Series. These series
have been divided into at least 4 stages and 15
formations, ranging from the Early Miocene Tampa
Stage to the Late Pliocene Miccosukee and
Citronelle Formations.
Puri and Vernon (1964) defined the Tampa
Stage (Lower Miocene) as comprising the Chatta-
hoochee Formation and the St. Marks Formation.
They included type-locality descriptions for both
formations, but did not attempt to map their areal
extent. Since 1964, several publications have re-
ported on the geology of various areas throughout
the Florida Panhandle, and all have used Puri and
Vernon's nomenclature. Their description describes
the St. Marks faces downdip as calcareous, and the
Chattahoochee facies updip as silty.
From well cuttings in Bay County, the Tampa
Stage limestones can be described as a white to light
gray limestone with biogenic, micritic, and crystal
grain types, moderately indurated with a micrite
cement; minor amounts of quartz sand and a trace of
pyrite. It often has a chalky appearance and contains
fossil remains of foraminifera, coral, and mollusks
(Schmidt and Clark 1980).
The thickness of the Tampa Stage in Bay County
is variable. Along the northern part of the county it
ranges between 50 and 100 ft thick. The top of the
Tampa Stage dips from approximately sea level in
the northern part of Bay Countyto nearly 500 ft below
sea level at the extreme southeastern corner of the
county. The Tampa stage is entirely subsurface in
Bay County. Banks and Hunter (1973) reported on
post-Tampa, pre-Chipola sediments in the eastern
Florida Panhandle. They called the clays, sands,
and shell beds found in Liberty, Gadsden, Leon, and
Wakulla Counties the Torreya Formation. The stra-
tigraphic position of the Torreya was determined by
the presence of Miogypsinida (a foraminiferan ge-
nus).
Gardner (1926) named the Alum Bluff Group to
include Chipola, Oak Grove, and Shoal River beds.
Cooke (1945) then divided the Alum Bluff Group into
three formations: the Hawthorn (east of the
Apalachicola River), the Chipola, and the Shoal
River (both west of the Apalachicola River). Puri
(1953), added the Oak Grove of Gardner (1926) to
Cooke's three formations and called them all faces
ofthe Alum Bluff Stage (Middle Miocene). Later, Puri
and Vernon (1964) included in the Alum Bluff Stage
the Shoal River, Oak Grove, Chipola, and Hawthorn
Formations and added the Pensacola Clay, Course
Clastics, and Fort Preston Formations.
Huddleston (1976) redefined the marine depo-
sits of the central Florida Panhandle. He included in
the Alum Bluff Group five formations: the Chipola
Formation, the Oak Grove Sand, the Shoal River
Formation, the Choctawhatchee Formation, and the
Jackson Bluff Formation. The main mass of the
Alum Bluff Group was considered by Huddleston to
be restricted to the eastern margin of the Gulf Coast
Basin and to the vicinity of the Chattahoochee Arch.
Planktonic foraminifera were used by Huddleston to
establish the time of deposition of the deposits. He
reported the Chipola Formation to be Early Miocene,
the Oak Grove Sand and part of the Shoal River
Formation to be Middle Miocene, the Choc-
tawhatchee Formation of Late Miocene Age, and the
Jackson Bluff Formation to be Pliocene in age.
The Chipola Formation was described by Puri
and Vernon (1964) in the area of its type-locality as
a blue-gray to yellowish-brown highly fossiliferous
Panhandle Ecological Characterization
marl studded with molluscan shells. This marly
faces only exists in the vicinity of the Chipola and
Apalachicola Rivers. Further west, Cooke (1945)
described two otherfacies: a sandy limestone which
he said is mostly subsurface, and a light-colored
coarse sandy facies that contains clay.
The lithology of the Chipola varies slightly
throughout its extent in Bay County; however, it can
be summarized as a very light orange sandy lime-
stone, with crystal, micrite and pellet grain types, fine
to coarse grain size, a sparry calcite and micrite
cement, with foraminifera, mollusks, coral and
bryozoans. Its induration, porosity, sand content,
and occasionally the presence of argillaceous mate-
rial, are the common lithologic variables.
The Chipola is distinguishable from the under-
lying Tampa sediments in that the Tampa is general-
ly a pure white limestone with relatively few fossils.
The Chipola is distinguished from the Bruce Creek
again by the latter being a purer limestone. This
distinction is a subtle one and often difficult to iden-
tify.
The Tampa and Chipola sediments become
indistinguishable from the Bruce Creek Limestone
downdip. The Chipola Formation along the Wash-
ington County line appears to strike almost east-
west and maintains a thickness of about 50 ft. The
top of the formation dips along the strike from near
sea level east of the Econfina Creek to about 150 ft
below sea level near East River, a dip of about 5 ft/
mile. Gardner (1926) reported on a comprehensive
study of the molluscan fauna of the Alum Bluff Group
from a number of outcrops in the Florida Panhandle
In 1965 Vokes suggested, as indicated bythe Murici-
nae (Mollusca: Gastropoda), that the formation
might be equivalent tothe Helvetian of Europe (lower
Middle Miocene). The benthic foraminifera of the
Chipola Formation were described by Cushman
(1920), Cushman and Ponton (1932), and Purl
(1953). Puri's report also included a list of identified
ostracod species. Planktonic foraminifera were
described by Gibson (1967), Akers (1972), and
Huddleston (1976). In addition to foraminifera,
Akers (1972) discovered the presence of some cal-
careous nannofossils in the Chipola material. Coral
species from the Chipola were reported by Vaughan
(1919) and Weisbord (1971). Finally, Bender (1971)
dated corals from the Chipola using the He/U radio-
metric age. He placed a concordant age of 14-18
million years on ten of the samples. This would put
the Chipola intheearly Middle Miocene orlate Lower
Miocene.
The Bruce Creek Limestone was named by
Huddlestonin 1976. Heincluded itin a groupof three
formations he mapped in coastal Walton County.
The three formations, in ascending order, are the
Bruce Creek Limestone, the St. Joe Limestone, and
the Intracoastal Limestone. Huddleston placed
these three formations in the Coastal Group, which
he explained was a new name for Alum Buff equiva-
lent carbonate units that underlie the coastal area of
Walton County and vicinity.
The Coastal Group is recognized by Huddleston
as far west as Niceville in Okaloosa County, and as
far east as Carrabelle in Franklin County. He further
states that it is not present in southern Washington
County, or at Alum Bluff in Liberty County.
This formation has been identified previously as
a limestone faces of the Chipola Formation (Gard-
ner 1926, Cooke and Mossom 1929). Limestones of
similar description were reported by Cooke and
Mossom (1929) in southwestern Washington
County in the vicinity of the Choctawhatchee River.
Samples from the type outcrop on Bruce Creek in
Walton County can be correlated lithologically with
cuttings and cores from areas in Bay County. Only
two lithologic types within the group can be recog-
nized. The two types consist of well-consolidated
white to light gray limestone, overlain by a poorly
consolidated argillaceous abundantly microfossilif-
erous limestone.
In Bay County, the Bruce Creek Limestone is a
white to light yellow-gray moderately indurated
granular to calcarenitic limestone. It may contain up
to 20% quartz sand, with common minoraccessories
being phosphorite, glauconite, and pyrite. In some
locations, sparry calcite or dolomite is present. It is
commonly cemented by micrite and becomes less
indurated toward the east. The Bruce Creek Lime-
stone is dominated by macrofossils, but microfossils
including planktonic and benthicforaminifera, ostra-
cods, bryozoans, and calcareous nannofossils are
also present.
2. Geology and Physiography
The Bruce Creek Limestone is overlain in Bay
County by the Intracoastal Formation orthe Jackson
Bluff Formation. It is distinguished from the Intra-
coastal unit by containing less sand, clay, and phos-
phate. It is also much more indurated and crystalline.
The Bruce Creek Limestone also contrasts in color
with a white to light yellow-gray being easily distin-
guished from the olive to gray green color of the
Intracoastal Formation. Lastly, the Bruce Creek
Limestone is less fossiliferous than the Intracoastal
Formation with its abundant fossils. In northern Bay
County, the Bruce Creek Limestone is sometimes
overlain by the Jackson Bluff Formation, which is
much less indurated and contains largerquantities of
sand and clay. The Jackson Bluff Formation essen-
tially is an olive-green shell marl, which is easily
distinguished from the white, crystalline to micritic
Bruce Creek Limestone.
The Bruce Creek Limestone extends westward
across southern Walton County and is thought to
lose its identity somewhere in Okaloosa County. To
the east, it has been identified in a core on St. Joe
Spit in Gulf County and in a core near Dead Lake in
Calhoun Coun Cty. The Bruce Creek Limestone is a
very low-angle, wedge-shaped deposit reaching a
maximum thickness along the gulf coast of about
300 ft. Planktonic foraminifera place the Bruce
Creek Formation inthe Middle Miocene (Huddleston
1976).
Sediments of the Choctawhatchee Stage in the
Florida Panhandle are exposed in a narrow band
extending from 20 mi west of Tallahassee, Leon
County, northwest to DeFuniak Springs, Walton
County, a distance of about 80 mi. The exposed
sediments are tan, orange-brown, or gray-green
sandy clays, clayey sands, and shell marls. The
outcrops generally are poorly exposed and small.
True stratigraphic relationships are poorly under-
stood (Puri and Vernon 1964, Rainwater 1964,
Waller 1969, Akers 1972, Huddleston 1976).
The Intracoastal Formation describes the body
of sediments which was called the Intracoastal Lime-
stone and St. Joe Limestone in Walton, Bay, Oka-
loosa, Calhoun, Gulf, and Franklin Counties (Hud-
dleston 1976). The Intracoastal Formation in Bay
County is a low-angle, wedge-shaped deposit up to
240 ft thick and occurring principally along the coast.
It thins and rises to the north, and extends westward
into southern Okaloosa County. The upper part of
the Intracoastal Formation, although predominantly
a quartz sand, can easily be distinguished from the
Pliocene to Recent sand because it contains phos-
phorite, poorly consolidated limestone, and foram-
inifera.
The Hawthorne Formation exhibits a wide range
of lithotypes in the Panhandle, including shallow
marine carbonates, restricted lagoonal clays, and
possible prodelta clastics. Thought to be middle
Miocene in age, it underlies most of the surface
outcropping sediments of the Tallahassee Red Hills
Inthe Panhandle. Its influence on plants and animals
is confined, therefore, to the lower slopes of ravines
where it has been exposed by gully erosion. It is
most common in central Florida where it was de-
scribed.
The Jackson Bluff Formation is found through
most of the central and southern parts of the Pan-
handle. Its outcrop pattern is a narrow belt extend-
ing from southern Washington County eastward to
the Jackson Bluff area of Leon County. From there
the outcrop belt apparently turns southwest where
exposures occur in the vicinity of Crawfordville in
Wakulla County (Banks and Hunter 1973, Hud-
dleston 1976).
The Jackson Bluff Formation along the lower
Ochlockonee River consists of three clayey, sandy
shell beds, differentiated on the basis of lithology and
mollusks. In Bay County the Jackson Bluff Forma-
tion i a ccs a calcareous sandy clay to clayey sand con-
taining large quantities of mollusk shells. Along the
coast in the vicinity of Bay County the Jackson Bluff
Formation Is underlain by the Intracoastal Forma-
tion. The limestone portions of the Jackson Bluff
Formation has more mollusks and is better indurated
than the Intracoastal Formation. In color, the
Jackson Bluff limestone are light grays in contrast
to the olive-green to buff color of the Intracoastal For-
mation (Schmidt and Clark 1980). Overlying the
Jackson Bluff Formation is the Pliocene to Recent
Sand Unit, which is readily distinguished from the
Jackson Bluff Formation by having no limestones,
very little clay, and almost no fossils. Studies of the
planktonic foraminifera of the Jackson Bluff Forma-
tion place Its age as Late Pliocene (Akers 1972,
Huddleston 1976).
Panhandle Ecological Characterization
The Miccosukee Formation is a series of silts,
sands, clays, and gravels that were deposited as
deltaic and fluvial sediments. It outcrops in the
Tallahassee Red Hills beginning about the Ochlock-
onee River (eastem margin of the Panhandle as we
have defined it), and is common eastward through
the Northern Highlands and Central Highlands of
peninsular Florida at the highest elevations.
Thought to be Late Pliocene in age, it may be
contemporaneous with the Citronelle Formation of
the Panhandle. Most of its physical and chemical
properties that affect plants and animals are the
same as those of the Citronelle Formation.
The Citronelle Formation is composed of prodel-
talc, deltaic, and fluvial deposits of sands, clays, and
gravels. These clastics appear to have been depos-
ited contemporaneously with the Miccosukee For-
mation, but are geographically separated from it.
The Citronelle deposits outcrop across the Northern
Highlands from Gadsden County and Liberty County
on the east to Escambia County on the west. They
range in thicknessfrom afewtensofft inthewestern
Tallahassee Red Hills to hundreds of ft in the West-
ern Highlands. In the Gulf Coastal Lowlands, the
Citronelle Formation thins toward the coast, and is
overlain by terrace sands and other Pleistocene and
Recent deposits.
Clays and silts in the Citronelle Formation give
soils derived from it their loamy character. The water
retaining capacity of these soils make them better
suited for a wide range of plants, such as the rich
groundcover flora of grasses and forbs in the long-
leaf clayhill community. These soils are more nutri-
ent rich from inorganic mineral leachates than the
pure quartz sands of sandhills.
The high clay and silt content of the Citronelle
Formation facilitates surface erosion by allowing
excessive rainwater to runoff over the surface of the
ground. Because of this and the generally higher
elevations reached inthe Panhandle bythe Northern
Highlands, landforms underlain by the Citronelle at
the surface are highly gullied. The topographic relief
of the Northern Highlands is due, primarily, to this
erosion. The ravine valleys provide many of the
lowervalley slopes that are naturally protected from
fire, allowing mesic hardwoods communities to
develop on them. Many animals and plants are
maintained in the fire-protected ravines, and accom-
modated by the higher humidity of ravines.
e. Pleistocene to Recent. The relatively short
period of the Pleistocene (2.0 million years) wit-
nessed several drastic fluctuations in sea level.
These were brought on by climate changes that
caused water in the oceans of the world to accumu-
late in continental ice sheets and extensive montane
glaciers. As the glaciers grew, ocean levels dropped
to as much as 300-400 ft lower than the present sea
level. During warm interglacial periods oceanwaters
rose, but probably did not exceed present sea level
until the past 10,000 years (end of the Pleistocene).
Evidence from the two lowerterraces, the Silver Bluff
(1-10 ft) and the Pamlico (8-25 ft), indicate that two
stands of the sea slightly higher than present may
have lasted for short periods of time before the
present sea level was established only about 6,000
years ago.
As a result of these post-Pleistocene fluctua-
tions, coastal regions of the Panhandle less than
about 25-35 ft above sea level have experienced a
complicated history of erosion, deposition, and re-
working of sediments from the action of rainfall, wind,
and waves. Dunes, bars, spits, beach ridges, and
other coastal features were stranded inland as sea
level receded. Some of these are delineated on the
physiographic map of the Panhandle (Figure 5).
The consequences of sea level fluctuations
during the Pleistocene had little effect upon the
present exposed land surfaces of the Panhandle
above the two terraces just mentioned. This is
because once the ocean withdrew from the higher
terraces it never returned. The surface of the Pan-
handle above the Pamlico terrace was exposed to
erosion and colonization by plants and animals just
as this area is today. Pleistocene sea level fluctua-
tions had their greatest effects, however, on the
lands that today are submerged under the ocean.
During lowered levels of the ocean surface much of
the present sea floor was exposed to the air and to
colonization by terrestrial plants and animals. Dur-
ing the Pleistocene the acreage of the Panhandle in-
creased by a factor of 1 1/2 to 2 times by newly
emerged Continental Shelf that was annexed to the
present coastline.
.*..A LOWLANDS
m L-
Figure 5. Physiography of the Florida Panhandle (after Purl and Vernon 1964, Brooks 1981b).
--
' u~:
I '
Panhandle Ecological Characterization
The present-day coastline is marked by beach
ridges, barrier islands, spits, lagoons, estuaries,
wave-cut cliffs, dunes, swales, sloughs, flats, and
other topographic features created by Recent
coastal processes. Beach ridges are marine in
origin, formed by wave swash, which pushes sand
up high as a berm adjacent to an existing beach,
effectively moving the beach to the seaward side of
the new sand berm, or beach ridge. This often
happens during certain types of storms. Beach
ridges usually occur side by side, as on St. Vincent
Island.
Dunes are of wind-blown origin and may as-
sume any shape or orientation. Drifting sand grains
become rounded and theirsurfacesare scratched or
frosted from abrasion by other sand grains. Dunes
can build up 30 ft or more on top of the beach ridges
they usually are perched on. Sand left on the beach
by wave swash dries out during high tide and is
subject to being moved up the dune face by the
proper winds. Two adjacent barrier islands of the
present coastline exemplify the complicated interac-
tions of wind, wave, sand supply, and offshore cur-
rents. St. George Island has Increasingly large wind-
created dunes going east to west. Immediately west,
however, St. Vincent Island is entirely composed of
relatively low elevation, wave-created berms aligned
in parallel sets. Shell fragments are less common on
dunes than on beach ridges because they are less
amenable to transport by wind than by water. The
size of the grains, the lack of a carbonate adhesive
leached from shells, and the rounded surface of
grains allows dunes to be eroded or reworked more
easily than beach ridges. Furthermore, the water
holding capacity of dunes is much less than that of
beach ridges, and dunes provide severely xeric soils
for plants. This is true of the actively forming dunes
along the present coastline as well as the ancient
dunes and dunefields stranded far inland at the edge
of ancient stands of the sea.
Barrier islands that have formed in the past
6,000 years or so are common along the coast of the
Panhandle. These generally are parallel to the coast
and consist of seriesof beach ridges, dunes, swales,
interdune flats, and sloughs. East to west, these are
Dog, St. George, St. Vincent, and Santa Rosa Is-
lands. Barrier spits form in similar fashion to barrier
islands, but are connected to the mainland at one of
their ends. East to west, they are Alligator Spit,
Indian Peninsula, St. Joseph Spit, Crooked Island,
Shell Island (once a spit, broken by dredging), and
Perdido Key. A lagoon is the brackish water bay
(also called an estuary) between barrier islands or
spits, and the mainland. Panhandle Florida is abun-
dantly endowed with brackish water lagoons, provid-
ing important habitat for sea birds and ocean fisher-
ies. Big Lagoon, Santa Rosa Sound, St. Andrew
Sound, and St. GeorgeSound are amongthe largest
of these.
The plants and animals of Panhandle Florida
have contact with and are influenced by the soils they
are rooted in, or live on, or burrow into. Most of the
soils of the Panhandle are of Pleistocene to Recent
age, and are presently actively being formed, re-
worked, and reformed by the action of rainwater.
Only on hardrock limestone outcrops such as those
along the Chipola, Apalachicola, Ochlockonee,
Sopchoppy Rivers or at various other places such as
Falling Waters State Park do older sediments di-
rectly influence animals and plants as a physical
substrate. Sediments older than the Pleistocene
also are exposed on ridge slopes and hogbacks of
the Northern Highlandsthat are underactive gullying
(so that the parent Miccosukee or Citronelle Forma-
tions are exposed). On the surface of lower slopes,
and especially in the bottoms of streams, rivers, flats,
and depressions, the sediments are of Recent origin.
Pleistocene and Recent sands and organic
deposits are the main surface sediments of the
Panhandle south of Cody Scarp. These occur in
thicknesses of a few inches to dozens of feet. They
are residual, leached, and reworked sediments from
older deposits.
2.4 Physiography
2.4.1 The Northern Highlands
The Northem Highlands (Figure 5) extend
across the Panhandle from the big bend region on
the east to Alabama on the west. To the north, they
extend into Georgia and Alabama along the entire
length of the northern boundary of Florida. The
almost continuous highland is parted by the larger
stream valleys, several of which form a large low
area called the Marianna Lowlands (see below). The
2. Geology and Physlography
marginal slopes of the Northern Highlands are well
drained by dendritic streams but the tops are gently
sloping plateaus.
The Northern Highlands are limited on the south
by the Cody Scarp which extends regionally through
the East Gulf and Atlantic Coastal Plains (Doering
1960). This outfacing scarp is the most persistent
topographic break in the State. Its continuity is
unbroken except by the valleys of major streams, but
its definition is variable. In many places, it can be
delineatedwith unequivocal sharpness; in others it is
shown only by a gradual reduction of average
elevation, and a general flattening of terrain as the
lower elevations are reached (Puri and Vernon
1964).
The significant subdivisions of the Northern
Highlands include the Western Highlands, Grand
Ridge, New Hope Ridge, Washington County outli-
ers (Knox Hill), and the Tallahassee Red Hills (Fig-
ure 5).
The Western Highlands is a belt of high, rolling
hills that stretch between Escambia County on the
west and Holmes and Walton Counties on the east.
The soils are derived fromthe undifferentiated sands
and clayey sands of the Citronelle Formation, provid-
ing dry conditions on the upland slopes and ridge
crests. Downslope it is common to find seepage
water emerging from gentle slopes, resulting in
wetland communities called hillside seepage bogs
(Clewell 1971, Wharton et al. 1976, Means and
Moler 1979). At the eastern end of the Western
Highlands in Holmes and Walton Counties, low, wet
karst depressions resulting from solution subsi-
dence of the underlying Tertiary limestones are
common. From Okaloosa County westward, how-
ever, subsurface solution activity is not recogniz-
able. The highest elevations in Florida occur in the
Western Highlands southeast of the border town of
Florala, Alabama, north of Walton County.
Grand Ridge and New Hope Ridge (Figure 5)
are two fragments of the Northern Highlands that
have been isolated between the Western Highlands
and the Tallahassee Red Hills by the Choctaw-
hatchee, Chipola, and Apalachicola river valleys.
Grand Ridge has little that is distinctive biologically,
but it does contain Ocheesee Pond, one of the larger
lakes of the Panhandle and a remnant wetland
formed in an ancient, abandoned bed of the
Apalachicola River. The Holmes Valley Escarpment
borders the northern edge of New Hope Ridge, and
holds promise for interesting biological exploration in
the future. North facing slopes in the Panhandle
often harbor northern relicts.
The high remnant hills of Washington County -
Orange, Rock, High, Oak, and Falling Water -
indicate that the Northern Highlands were once
continuous and that the Western Highlands, New
Hope Ridge, Grand Ridge, and Tallahassee Red
Hills were connected.
The Tallahassee Red Hills are a heterogeneous
mix of rolling topography that sweeps south from the
Georgia State line to Cody Scarp, and runs from the
Apalachicola River on the west to the Suwannee
River basin on the east. We have defined the
eastern margin of the Panhandle as lying along the
bed of the Ochlockonee River because a strong
change occurs here in the underlying geology and
surface physiography. East of the Ochlockonee
River, the Tallahassee Red Hills lie in the Florida Big
Bend, and the surface of the landform there is
dominated by subsurface limestone solution. Large,
solution subsidence basins dot the landscape and
contain large lakes such as LakesJackson, lamonia,
Miccosukee, and Lafayette, and a host of smaller
lakes and swamps. West of the Ochlockonee River,
in the Panhandle, the rolling relief of the Tallahassee
Red Hills is caused primarily by surface runoff. The
terrain in this area is more relieved than any other
area in Florida because of short tributaries incising
the hills. In addition to the the deep stream valleys,
or ravines, there are high (>200 ft) bluffs overlooking
the Apalachicola River on the east.
2.4.2 The Marianna Lowlands
The Marianna Lowlands in Holmes, Washing-
ton, and Jackson Counties cover a rectangular area
of approximately 30 x 64 mi and extend into Alabama
and Georgia along the principal streams. They are
bounded on the west by the Western Highlands, on
the southeast by Grand Ridge, and on the south by
New Hope Ridge. Because of the abandoned val-
leys and stranded alluvial deposits, it is believed that
Marianna Lowlands were generally developed along
the valleys of the Apalachicola, Chattahoochee,
Chipola and Choctawhatchee Rivers.
Panhandle Ecological Characterization
The land surface is well drained and has a well
developed dendritic stream pattern. It is pocked by
sinks interspersed with rolling hills and abruptridges.
The ridges are bounded by stream channels or by
sink rims. Broad, shallow basins are generally
present, some filled by water. The Marianna Low-
lands possess Florida's most extensive system of
air-filled cavern passageways, and the only ones in
the Panhandle. The calcium-rich soils that develop
on top of the limestone are often moist and rich in
nutrients.
2.4.3 The Gulf Coastal Lowlands
The Gulf Coastal Lowlands physiographic reg-
ion extends inland to its contact with the Northern
Highlands along Cody Scarp (Figure 5). It is contin-
uous from southern Escambia County onthe west to
Wakulla and southern Leon Counties on the east.
The Guff Coastal Lowlands are generally low in
elevation and poorly drained on the east, but rise to
form a high, sandy, well-drained plateau whose
southern margin is a wave-cut escarpment west of
Walton County. Coastalterraces characterize many
of the landforms of the Gulf Coastal Lowlands and
their low scarps form the boundaries between them.
The Gulf Coastal Lowlands are at least as di-
verse physiographically and biologically fromwest to
east as are the Northern Highlands. Purl and Vemon
(1964) listed nine subdivisions and there may be
more. Immediately adjacent to the coast, the Gulf
Coastal Lowlands are composed of barrier islands,
lagoons, estuaries, coastal ridges, sand dune
ridges, and relict spits and bars, with intervening
coast-parallel valleys. Inland, northern Bay, south-
ern Washington, and western Calhoun Counties
have well developed karst ponds and lakes.
Greenhead Slope isa massive sand depositthat
is pocked by circular depressions and round lakes.
Aside from the limestone-dominated Marianna
Lowlands, Greenhead Slope is the only other land
area of the Panhandle exhibiting extensive karst
features. It possesses a few steepheads, some
draining into Econfina Creek and others into karst
depressions.
Beacon Slope east of the Apalachicola River
has more steepheads developed in it than any other
part of the Panhandle, although by sheer volume of
flow some on Eglin Air Force Base are larger. Be-
cause Beacon Slope is immediately adjacent to and
belowthewelldeveloped Apalachicola ravines inthe
Tallahassee Red Hills, the steephead ravines of
Beacon Slope support most of the same endemic
and relict species that are found just north.
Beacon Slope, Fountain Slope, Greenhead
Slope, and the massive sand deposit in southern
Santa Rosa, Okaloosa, and Walton Counties may all
be ancient coastal sand deposits formed contempo-
raneously during the Pliocene when the sea stood
near Cody Scarp. Today they are stranded inland by
lower sea level, but it is significant that each feature
contains numerous steepheads and endemic plants
and animals that may have evolved on each feature
during the long period when each was part of a
developing barrier island-lagoon set.
Relict bars and spits are common in Gulf, Lib-
erty, and Franklin Counties. In fact, ancient bird's-
foot deltas can be traced on the land surface on both
sides of the lowerApalachicola River. Moreover, this
part of the Gulf Coastal Lowlands is biologically so
distinctive that it probably deserves its own physi-
ographic rank. At least 15 races and species, and
one genus of plants and animals have their distribu-
tions centered on the lower Apalachicola valley
(Means 1977). Many unique, silt-bottomed savan-
nas and cypresswetlands occurhere, andthe region
beckons for further exploration.
2.5 Regional Marine Geology
Two regional geologic features control the
coastal configuration of the Florida Panhandle: the
ApalachicolaorSouthwest Georgia embayment and
the Chattahoochee arch (Figure3) (Schnable 1966).
The Apalachicola embayment is a shallow basin
(syncline) situated between the Ocala and Chattah-
oochee uplifts It is located where the east-west
strike of the coastal element changes to approxi-
mately north-south in southwestern Georgia and
northern Florida (Murray 1961). The Apalachicola
delta lies near the center of the embayment. The
thickness of the Pleistocene and Miocene sediments
in the eastern portion of the area reflectthe influence
of the Ocala uplift as a structural high (Schnable and
Goodell 1968).
4. Geology and Physiography
The thickness of the tertiary sediments in the
northeastern Gulf of Mexico is substantially lessthan
those of the northwestern and north central gulf
(Vause 1959). This is probably a result of the
Apalachicola delta region lying further from the main
axis of the Gulf Coast Geosynclinethan most coastal
areas to the west and as a result being more stable
and structurally less complex (Schnable 1966).
Pleistocene to Recent sediment thicknesses along
the present coast vary from less than 3 m in the
easternmost portion of the Panhandle to 36 m in the
westernmost part (Figure 6) (Schnable 1966).
Several investigators have examined the off-
shore sediments in the region (Lapinski 1957, Milton
1958, Chen 1978). West of Ochlockonee Bay, the
Apalachicola and Ochlockonee Rivers supply allu-
vium downdrift for a system of barrier islands (Dog
Island, St. George Island, and St. Vincent Island),
beaches, spits, and bars. The Ochlockonee and
Apalachicola are the eastem most rivers carrying
appreciable amounts of detrital and mineral matterto
the gulf. The region from the western end of St.
George Island to the Ochlockonee Bay is classified
as a low-energy area (Figure 7) (Tanner 1960b). The
sediment from alluvial and shelf sources is mostly
lost to coastal deposition west of St. Joseph Bay
where the 25-m depth contour approaches the
nearshore region and funnels material from the
westward drift out into deeper water (Stout 1984).
Further west, Santa Rosa Island receives sediment
downdrift from Choctawhatchee Bay and sands from
the Continental Shelf (Kwan 1969).
Most of the fine-grained sediment carried by the
Apalachicola and Ochlockonee Rivers is contained
within the estuaries (Kofoed and Gorsline 1963).
Kofoed (1961) and Schnable and Goodell (1968)
concluded that no significant quartz sand was being
supplied to the littoral drift system outside the barrier-
island chain. They contended that the "large volume
of sand composing the barrier islands and offshore
shoals can have been supplied only during lower
sea-level stands." There has been extensive beach
erosion onthe spits and barrier islands in recent time
in this area of supposed excess sediment (Wamke
1967). Clear evidence for erosion are tree stumps in
the water on the beaches near East Point in the
Apalachicola system and on St. George Island.
The littoral drift, or longshore sand transport,
along the Panhandle coast has been described by
Tanner (1964), Bruno (1971), and Walton (1976).
Figure 8 gives a view of littoral drift along a portion of
the Panhandle from Cape San Bias in Gulf County to
the western border of Okaloosa County. From the
western end of the Panhandle toward Bay County,
the shoreline becomes concave. This natural con-
cavity is broken by St. Joseph Bay. The area from
Panama City west to East Pass is presently under-
going erosion. In recent geologictimesthis area may
have been a source of sand for areas to the west
(Walton 1976). In contrast, the shoreline from East
Pass (St. Andrew Bay system, Bay County) to Per-
dido Pass may have been an area of accretion
(Santa Rosa Island is evidence) in recent geologic
times, though Santa Rosa Island is now in a state of
equilibrium.
There are no true barrier islands present in the
region west of St. Joseph Bay to Destin (Tanner
1960b). Moderate-energy waves form the gulf front
beaches. From Panama City Beach to Destin the
shoreline is a mainland beach (Gorsline 1966). For
approximately 85 km the beach is unbroken, with
only small streams interrupting the continuity. Asso-
ciated with the larger streams are small brackish-
water bays. A wide recent beach abuts a prominent
bluff 6-10 m high. The present coast is relatively
stable.
From Choctawhatchee Bay Pass westward to
the Alabama border, a series of narrow barrier is-
lands border the mainland. Santa Rosa Island is
nearly 81 km long and is not more than 0.7 km wide.
It represents the largest unbroken stretch of beach in
the eastern Gulf (Brooks 1973). The beach is com-
posed of pure white quartz sand (median diameter
approximately 0.25 mm). During heavy storms there
is local washover across the island. There is
extensive dune development on the eastern fifth of
the island.
Near the western end of the island salt marsh
peat is exposed on the foreshore. The foreshore
slope is relatively steep (approximately 90-10) so
that the 15-m depth contour comes within 0.6-0.8
km of the shoreline. Because of this steep ramp, the
area has recorded some of the highest waves in the
northeast Gulf of Mexico (Gorsline 1966, Brooks
1973).
Choctawhatchee Bay
<00 1 a n 0 \
co _o / | 1 0
!West a / East :
se 0 e.
..
4200 AND CtTO
32 0
1200 ECLAY FOt t
S 2000. CENE COAOO IC q T IA
1200 UP rO---S- -E PENS A I 5 10 1 20
Figure 6. The thickness of Eocene to Recent sediments along the Panhandle coast from Choctawhatchee Bay to the Alabama-
Florida border (after Marsh 1966).
Florida border (after Marsh 1966).
>.
4. Geology and Physiography
ALABAMA
Figure 7. Coastal energy levels and tidal ranges for the northeastern Gulf of Mexico (after
Stout 1984).
87
SANTA ROSA
'^
-;"^,
860
a85
ALABAMA
HOLMES
GEORGIA
GADSDEN I 'V .
W NASHINGTON i A _S
1 ------ CALHOUN -
- CALH UN JEFFER -
BAY LEON
WESTWARD NET DRIFT
EASTWARD IOR SOUTHEASTWARDI
NET DRIFT
0 10 20 30 40 50
1 I I Mites
LITTORAL DRIFT
g 100,000 Icubicyds.peryr. GULF OF MEXICO
20 0
200,000
Figure 8. Schematic of net littoral drift along "idealized" Panhandle coast (after Walton
1976). Qa shows magnitude of littoral drift in cubic yds/yr.
OKALOOSA
WALTON
Panhandle Ecological Characterization
The northeastern Gulf of Mexico is not as tec-
tonically active as areas to the west. The Apalach-
icola delta region has been a relatively stable area
since at least Pamlico (Sangamon -the last glacial
recession) time (Schnable 1966).
There are two prominent offshore morphological
features present in the eastern portion of the Pan-
handle region: the two large shoal areas off Cape
San Blas/Cape St. George (Stauble 1971) and the
submarine sand bodies in the nearshore gulf off
Choctawhatchee Bay (Figure 9; Hyne and Goodell
1967). The two broad shoals extend nearly 16 km
into the gulf and are characterized by a series of
broad ridges and troughs. Mean grain size of the
quartz sand increases seaward from the beach and
therefore the sand in these shoals is coarserthan the
sand now being transported by the longshore drift
system (Schnable 1966). The present energy levels
along this coast are not sufficient to redistribute or
remove sand from the shoal areas or sand bodies
(Tanner 1961, 1964; Tanner et al. 1961). The outer
shoals have remained relatively unchanged for over
a century (Schnable 1966). The sands in these
offshore areas are relict and were probably originally
deposited at some early low stand of sea level.
Several mechanisms have been proposed to
explain the origin of the shoals. One is a storm-surge
Figure 9. Nearshore bottom topography off Choctawhatchee Bay showing sand body features (after
Hyne and Goodell 1967).
4. Geology and Physiography
phenomenon that formed the ridge and trough con-
figuration (Tanner 1960a). Others have proposed
that the shoals are drowned barriers, although the
sand has been extensively reworked. In addition,
the ridges of the shoals contain concentrations of
heavy minerals that may indicate a dune origin
(Schnable 1966).
An interesting discovery has been made in the
offshore waters south of Panama City Beach. Rem-
nants of an ancient forest are present at a depth of
approximately 18 m directly south of the beach and
in 6 to 15 m of water nearer the St. Andrew Bay
entrance (Lawrence 1974, Burgess 1977, Salsman
and Ciesluk 1978). The latter site is located beneath
sediments comprising the present-day barrier island
complex. The wood dates from 27,00 to 36,500
years old and is believed to be part of a large forest
that covered the area during a lower sea level stand.
The forest extends many kilometers south of the
present shoreline. The wood is mostly pine but
contains small amounts of hardwoods such as oak,
beech, hickory, and elm. This suggests the vegeta-
tion was very similar to present-day stands 32-48
km north of Panama City. The submerged forest
Cape San Bias
MR /,,
Apalachicola
\ MO
further supports the contention that the present-day
beaches and islands are recent geologic features.
2.6 Local Marine Geology
The following section is a discussion of the origin
and geological aspects of the major bay systems
included in the Panhandle region.
2.6.1 Ochlockonee Bay
The Ochlockonee Bay represents a drowned
river valley that was cut during lower stands of sea
level in the Pleistocene. Bottom topography at the
mouth of the bay resembles a drowned delta with two
linear shoals on each side of the channel that may
represent an old river channel with natural levees on
each side. The "old" Ochlockonee River probably
had several routes to the gulf during the late Pleisto-
cene (Schnable 1966).
The stratigraphy of the nearby region is unique
in the Panhandle. The Miocene is very close to the
surface at the present coastline in the vicinity of
Turkey Point-St. Teresa (Figure 10). From there the
Carrabelle St.Teresa
MN MP
.- ". ' t,..: "}
V ::, .. : , .
......?
, : . .
Figure 10. Stratigraphy of coastal region from
Panhandle (after Schnable 1966).
RECENT
PLEISTOCENE Upper Sequenc:e
SPLEISTOCENE Lower Sequen.:e
MIOCENE Choctawhatchee
SMIOCENE -Chipola?
O 5 10mi
Cape San Blasto Ochlockonee Bay in the eastern
23
080 -
o
120
-160
C
Panhandle Ecological Characterization
surface dips to the southwest and the Pleistocene- of the past lagoon, sand encroachment has been
Miocene contact is approximately 45 m below the slow and limited, and a large portion of the older
ocean floor off Cape San Bias. surface remains relatively unobscured.
2.6.2 Apalachicola Bay
During the Cretaceous period, the present
Apalachicola River system was submerged under
ancient seas (Tanner 1983). The origin of the
present Apalachicola River probably occurred some
time during the Miocene epoch (Livingston 1984).
The present structure of the bay is nearly 10,000
years old (Tanner 1983). The present barrier island
chain formation began approximately 5,000 years
ago when sea level reached its modern position. It
was at this time that the general configuration of the
bay was determined, except for the southward mi-
gration of the delta flat (Tanner 1983).
2.6.3 St. Joseph Bay
Stewart and Gorsline (1962) described the fol-
lowing sequence of events leading to the formation
of modern St. Joseph Bay:
(1) Following the last rise of sea level (approxi-
mately 5,000 years ago), a series of north-south
trending beach ridges was formed and an open
coast profile was established offshore. An even
older set of ridges was submerged and subjected to
marine degradation, resulting in the formation of a
shoal trending south-southwest from the mainland
through the Cape San Bias area.
(2) A large distributary of the Apalachicola River,
its course controlled by beach ridge development,
emerged about 8 km north of the present bay and
deposited a wedge of fine-grained material overthe
terrace sediment. At approximately the same time,
gyral currents established by the presence of the
southern shoal initiated spit growth from the east.
(3) Rapid spit development segregated a large
portion of the older surface and prevented substan-
tial filling of the bypassed area. At this time, the
detrital supply from the distributary had ceased and
sand supplied by longshore drift and biologic carbon-
ate formed the major contribution.
(4) Development of stronger tidal currents in
recent times controlled spit growth and furnished a
mechanism for the transport of sand into the basins.
Sand has completelycovered the fine-grained mate-
rial to the north. Under the lower energy conditions
Present-day sedimentation in the bay comes
from 2 dominant sources: the coastal transport of
clean quartz sand from the east and biological activ-
ity within the area itself. In the absence of a substan-
tial amount of silt-size quartz particles, carbonate
tests and shell fragments increase in importance as
the applied energy of the environment decreases
southward in the lagoon. Residual gravels and
sands dominate a sizeable portion of the southern
slope of the bay that is removed from active deposi-
tion of detrital material (Figure 11).
Since the formation of the enclosing spit, a
reduced rate of deposition has preserved the bottom
contour in the central portion of the lagoon. The
depth and gradient closely approximate that of the
offshore slope (Stewart and Gorsline 1962). There
is a far larger accumulation of clay in the central bay
basin than can be accounted for by present minor
sources. This has led to the conclusion that these
fine sediments represent a relict surface produced
by the discharge of an old distributary of the
Apalachicola River.
The sediments of the area are typical of those
from a Coastal Plain source. Small differences can
be attributed to attrition and loss in transport. Less
than 1% of the typical east gulf "kyanite-staurolite"
suite of heavy minerals is present. Kaolinite,
montmorillonite, and illinite are the clay minerals
present, with kaolinite dominating.
2.6.4 St. Andrew Bay System
The St. Andrew Bay system is a typical tidal
embayment. It appears that it was formed during the
last major rise in sea level (the Holocene transgres-
sion) that took place approximately 5,000 years ago.
As sea level rose and flooded the valley of a local
river system, ocean waves and longshore currents
built up a barrier bar across the mouth of the resulting
bay.
Uniform sediment ridges on the bottom of St.
Andrew Bay were documented by Salsman et al.
(1966). The ridges, composed of a fine sand, were
asymmetric, with steep slopes, 30 to 60 cm high,
4. Geology and Physiography
100
A
GRAVEL
90
j3 3 \3
SANDo-- 10--- SILT
100 100
100
CLAY
90
SAND 0 10-- SILT
100 100
GULF OF MEXICO
: . i -: . ..
NAUTICAL MILES
1 0 1 2 ^."
^*";;"?;%^^
J / ./ ,/ / /^ t /
///// ///^Y.
.-///////////
/ / / 7 / /ii -" / / /
/ '/ / / /'7
..'/ / ////
"//." // /-""w / ."/ / F/
//.'7 7//7//////
/7//7///7//.//;
l///i//i/ / /'/!
r-/////////'///.
'////i///l///
\\////'i///////
I\/"/ / / // // ///A'
\ /'/////// /\
\\\ / / / / / / // d\\\\
SEDIMENT TYPE
O SAND
SHELL GRAVEL St. Joseph Bay
SANDY GRAVEL
GRAVELLY SAND .
lo GRAVELLY SAND
.O SILTY CLAYEY SAND
I SANDY CLAYEY SILT
E CLAYEY SILT
Figure 11. Surface sediment composition in St. Joseph Bay (after Stewart and Gorsline 1962).
Panhandle Ecological Characterization
facing down current, and had 13 to 20 m wave-
lengths. The predominant flood tide caused them to
migrate northeastward at an average rate of 1.35 cm
per day. The migration rate was very sensitive to
changes in current speed. Near the leading edge of
the ridge zone, where sand transportwas primarily of
bed-load mode, each ridge passing a point left be-
hind an average 12 cm-thick sand layer.
Holmes and Goodell (1964) have reported on
the sediments in St. Andrew Bay.
2.6.5 Choctawhatchee Bay System
The region presently covered by the Choctaw-
hatchee Bay was as much as 92 m above sea level
during the Pleistocene epoch (Puri and Vernon
1964) and became gradually inundated by oceanic
waters in more recent times. As the Gulf of Mexico
approached its present level, a persistent westerly
drift of littoral sand created Moreno Point. This
barrier eventually isolated the bay from the gulf,
except for a narrow passage through the embay-
ment now known as Old Lagoon Pass. At times
before the formation and stabilization of East Pass,
Choctawhatchee Bay became a freshwater lake
when periodic shoaling closed the natural pass.
The land immediately adjacent to the bay is
composed of unfossiliferous sand and clay deposits
of Pleistocene and Tertiary age (Puri and Vernon
1964). Moreno Point is part of a massive sand ridge
described by Tanner (1964). Sand cliffs from 2 to 4
m high make up the north shoreline of the bay. The
narrow Gamier and Rocky bayous in the northwest
corner of the bay have very steep shores, with sharp
slopes extending down to depths of more than 10 m.
This contrasts with the eastern end, which is marshy
due to poor drainage, and the western end, which is
composed of residual sand. Both of these ends are
relatively shallow, with low gradient slopes. The
bedrock limestone underlying Choctawhatchee Bay
is found at a depth of approximately 45 m (Tanner
1964). The recent sediments of the bay are describ-
ed by various authors (e.g., Postula 1967, Palacas et
al. 1968,1972).
Goldsmith (1966) reported a large contrast in
condition between the present sedimentary environ-
ment and the one previously occupying the area. He
reported the following sequence of events leading to
the formation of Choctawhatchee Bay.
(1) A sharp rise in sea level (7,000 to 20,000
years ago) inundated the Pleistocene River valleys,
from the coastal embayments that are presently the
bayous on the north side of the bay. Between 3,000
and 7,000 years ago, when the rate of sea-level rise
slowed, the westward longshore drift system began
toform Moreno Point, the eventual barrierspit. It was
not until sometime after3,000 years ago that Moreno
Point effectively closed off the bay.
(2) Isolation from the Gulf of Mexico had a pro-
found effect upon the sedimentary environment
within the bay, producing modifications in three fac-
tors that caused the sediments to undergo radical
alteration. Biologically, the present environment
lacks the prolific shell-producing organisms of the
past. Physically, the entrapment of fine material
brought by the Choctawhatchee River may have
brought on the decline of the formerly abundant and
diverse molluscan life of the bay. Finally, the
changes in both biological and physical conditions
caused modifications inthe physiochemical environ-
ment, as reflected in the low alkalinity and highly
reducing character of the surface sediments of the
bay.
Minor fluctuations in sea level within historical
times in Choctawhatchee Bay have been documen-
ted by the presence of submerged trees (approxi-
mately 0.5 m under water) next to emergent marsh
remnants (1 m above water) (Goldsmith 1966).
These features are located at about the middle of the
south shoreline of the bay. This change in water
level of the bay may be related in part to general
coastal subsidence determined by Marmer (1952)
from tidal observation.
Of historical note, farmers originally dug a ditch
across Santa Rosa Island that eventually became
the main Destin channel and resulted in major
changes in the depositional and erosional patterns
within the bay. The channel has since been main-
tained by the U.S. Army Corps of Engineers.
2.6.6 Pensacola Bay System
The recent sedimentology of the Pensacola Bay
system is a result of watershed erosion since the
Pleistocene epoch (Olinger et al. 1975). During the
Pleistocene, Citronelle deposits were reworked and
4. Geology and Physiography
intermixed with marine terrace sediments (Marsh
1966). These deposits are presently eroding. Pres-
ent-day sediments consist primarily of unconsoli-
dated sand, silts, and clays of the Coast Plain Prov-
ince that were deposited before the last sea-level
rise. This layer is underlain by a veneer of Pleisto-
cene terrace deposits that overlie tertiary beds of
sand, silt, and limestone (Figure 12). The Citronelle
Formation, the only formation with marine outcrops
in the region is composed of layers of sand, gravel,
iron-cemented sandstone, fossil woods, and kaolin-
ite (Marsh 1966).
Horvath (1968) described the recent sedimen-
tology of the Pensacola Bay system:
(1) Sediments enter into the system from two
sources: stream discharge from the surrounding
land, and wave and current action that bring them
into the bay from the Gulf.
(2) The Escambia Riverdischarges morecoarse
material into the bay than do the other rivers.
(3) Sediment distribution reflects the bay'scircu-
lation pattern, consisting of strong north-flowing
currents along the eastern shores and south-flowing
currents near the western coasts.
(4) Sand-size sediment predominates with silt-
clay being the second most abundant.
(5) Grain size increases in every direction away
from the bay center.
(6) The main mineral constituents are quartz,
kaolinite, montmorillonite, and calcite.
(7) The Santa Rosa Sound is different from the
three bays in the Pensacola Bay system, with a
coarser mean grain size and lower average silt-clay
content. Most of its sediments were probably de-
rived from offshore sources and are not of fluvial
origin.
2.7 Offshore (Outer Continental Shelf)
Oil and Gas Reserves
Recently, the development of the Outer Conti-
nental Shelf (OCS) oil and gas resources has been
a major concern of coastal Panhandle residents. At
present, three offshore lease areas lie off the imme-
diate Panhandle coast (Figure 13): (1) the Pensa-
cola area; (2) the Destin Dome area, and; (3) the
Desoto Canyon area.
Since the early 1970's, various oil companies
have maintained exploratory interest in these lease
areas. The Destin Anticline and the southwest
corner of the Pensacola area are believed the most
promising as hydrocarbon-producing areas (Figure
13). Eighteen exploratory wells have been drilled
within the Destin Dome area in the Smackover
geologicalformation, as of the summer of 1985. The
depths to which the wells were drilled, 5185-5795 m,
indicate natural gas may be a more likely yield than
oil. Thus far, the natural gas discovered in the
Smackover Formation in other regions has con-
tained hydrogen sulfide (said to be "sour") that is
corrosive and must be subjected to more costly
processing than higher quality gas. Offshore oil
activities have the potential for many harmful im-
pacts to the nearshore coastal habitats. Some of
these are discussed in the chapters dealing with the
individual estuarine and marine habitats.
Panhandle Ecological Characterization
GENERALIZED
GEOLOGIC
COLUMN
OF FORMATIONS IN THE WESTERN FLORIDA PANHANDLE
SERIES FORMATION
P SCT.SNCNFORMATION
PLEISTOCENE .....:: MARINE TERRACE DEPOSITS: Sand, light tan, fine to coarse
CITRONELLE FORMATION: Sand with lenses of clay and gravel.
,.Sand, light-yellowish-brown to reddish-brown, very fine
to very coarse and poorly sorted. Hardpan layers in
PLEISTOCENE (?) upper part. Logs and carbonaceous zones present in
places. Fossils extremely scarce except near the coast
where shell beds may be the marine equivalent of the
S.fluvial faces of the Citronelle.
MIOCENE COARSE CLASTICS: Fossiliferous sand with lenses of
clay and gravel. Sand is light-gray to light-brown,
very fine to very coarse and poorly sorted. Fossils
abundant, mostly minute mollusks. Contains a few zones
of carbonaceous material. Lower part of coarse plastics
UPPER MIOCENE present only in northern part of area, interfingering
with Pensacola Clay in the central part.
PENSACOLA CLAY: Formation consists of an Upper Member
and Lower Member of dark-to-light-gray, tough, sandy
clay; separated by the Escambia Sand Member of gray,
fine to coarse, quartz sand. Contains carbonized
plant fragments, and abundant mollusks and foramin-
S- ifers. Pensacola Clay is present only in southern
-- half of area, interfingering with the Miocene coarse
UPPER MIDDLE TO c-_- plastics in the central part.
LOWER UPPER MIOCENE -
CHICKASAWHAY LIMESTONE AND TAMPA FORMATION UNDIFFERENTIATED
LOWER MIOCENE AND Tampa: Limestone, light-gray to grayish-white, hard,
UPPER OLIGOCENE with several beds of clay; Chickasawhay: Dolomitic
limestone, gray, vesicular.
MIDDLE OLIGOCEE BUCATINNA CLAY MEMBER OF BYRAM FORMATION: Clay, dark-gray
MIDDLE OLIGOC soft, silty to sandy, foraminiferal, carbonaceous.
OCALA GROUP: Limestone, light-gray to chalky-white foram-
UPPER EOCENE inifers extremely abundant, esp. Lepidocyclina; corals,
echinoids, mollusks, bryozoans.
- LISBON EQUIVALENT: Shaly limestone, dark-gray to grayish-
-- -cream; hard, compact; glauconitic; with thick intervals
Sof dense, light-gray shale.
MIDDLE EOCENE - -
TALIAHATTA FORMATION: Shale and siltstone, light-gray, hard,
with numerous interbeds of gray limestone and very fine
to very coarse, pebbly sand. Foraminifers locally abun-
Sdant.
-HATCHETIGBEE FORMATION: Clay, gray to dark-gray, micaceous,
SLOWER EOCEE siltv, with beds of glauconitic shale, siltstone, and
LOWER EOCE shalv limestone. Mollusks, foraminifers, corals, echin-
oids. Bashi Marl Member (about 10 feet thick) at base.
Figure 12. Generalized geologic column of formations In the western portions
of the Florida Panhandle (after Marsh 1966).
28
4. Geology and Physiography
Figure 13. OCS leases in the Pensacola and Destin Dome Blocks offshore from west Florida (Lynch
and Risotto 1985).
Chapter 3. CLIMATE
3.1 Introduction
The Florida Panhandle experiences a mild,
subtropical climate as a result of its latitude (300- 31
N) and the stabilizing effect of the adjacent Gulf of
Mexico (Bradley 1972). The waters of the gulf
moderate winter cold fronts by acting as a heat
source and minimize summer temperatures by pro-
ducing cooling sea breezes. This gulf influence is
strongest near the coast, weakening inland. Fairly
detailed long-term climatological summaries are
available forApalachicola and Tallahassee. Though
Tallahassee lies a few miles outside the eastern
boundary of what we call the Panhandle, it is the
location of much data collection and will be used to
provide a more comprehensive report. More limited
data are also available for Pensacola and certain
other Panhandle locations (Jordan 1973). The loca-
tions of NOAA climatological stations are shown in
Figure 14.
3.2 Climatological Features
3.2.1 Temperature
The annual average of the mean daily temper-
ature is in the upper 60's Fahrenheit with mean
summer temperatures in the low 80's and mean
winter temperatures in the low 50's. Annual and
seasonal temperatures vary greatly (Figures 15 and
16) with summer highs generally in the low to mid
90's with occurrences of 100 OF or higher infrequent.
The summer heat is tempered by sea breezes along
the coast and up to 50 km inland, as well as by the
ALABAMA
Figure 14. NOAA climatological station sites in the Florida Panhandle (after Wagner et al. 1984).
3. Climate
ALABAMA
NOLMC$
S acK~.O
GULF OF MEXICO
Mean maximum temperature-July
89
0 10 20 30 40 50
I 1 i- 1Miles
ALABAMA
SANTA Po1*
GULF OF
I -/ IJACKSON
-TOM
MEXICO
Mean minimum temperature-July
Figure 15. Isotherms for mean maximum and
Panhandle (after Fernald 1981).
mean minimum July temperatures in the Florida
31
7 --
1
i
Panhandle Ecological Characterization
8GG
ALABAMA
.65.
TON L.
k. / __ _
LEON I
__ QI,- \
GULF OF MEXICO
S61
0 10 20 30 40 50
M1 iles
Mean maximum temperature-January
37 ALABAMA
MOL"CS
--- I
JACC34OW
S37 r
3737
GULF OF MEXICO
GULF OF MEXICO
49
49
Mean minimum temperature-January
Figure 16. Isotherms for mean maximum and mean minimum January temperatures in the Florida
Panhandle (after Fernald 1981).
32
1840
~1_~___1 ____ _1__1
84
3. Climate
cooling effect of frequent afternoon thundershowers.
Thundershowers occur on approximately half of the
days during summer and frequently cause 10 to 20
degree drops in temperature (Bradley 1972).
Winter temperatures are quite variable due to
the frequent passage of cold fronts. The colder of
these fronts are of Arctic origin and may bring mini-
mum temperatures ranging from 15 to 20 OF with
single-digit lows some years. Temperatures rarely
remain below freezing during the day and the cold
fronts generally last only 2-3 days. Temperatures in
the 60's OF and sometimes 70's OF often separate the
cold fronts. This weather pattern results in average
low temperatures in the mid 40's OF during the
coldest months (mid-January through mid-March).
3.2.2 Rainfall
The Florida Panhandle has two peak rainfall
periods: a primary one during summer (June- Au-
gust) and a secondary one during late winter through
early spring (February-April). Additionally, there
are two periods of low rainfall: a pronounced one
during October-November and a lesser one in
April-May (Figure 17). Average annual rainfall
across the Panhandle is near 152 cm, varying from
approximately 163 cm at the west end to about 142
cm at the east end (Figure 18). The dearth of
gauging stations in some Panhandle regions may
Pensacola (1923-1980)
Tallahassee (1885-1980)
*.... Apalachicola (1879-1980)
20 ........................ .. .. t.,.,. ..............
15 ......................... ..
sites in Florida Panhandle (data from U.S. Dept.
Commerce 1980a,b,c).
affect the accuracy of the isopleth placements in
these figures. The annual rainfall varies widely
(Figure 19), and the maximum recorded amount has
ranged from 73 cm at Pensacola in 1954 to 284 cm
at Wewahitchka in 1966 (Wagner et al. 1984).
During rainy years the maximum rainfall tends to
occur near the coast; however, during dry years the
rainfall maximum occurs farther inland. Rainfall
patterns tend to be more consistent approximately
25-95 km inland (Jordan 1984). Rainfall gradients
are quite strong along some portions of the gulf
coast; annual totals are as much as 12-25 cm less
at stations very near the coastline than at those a few
kilometers inland (Jordan 1973).
Studies of the distribution of summer rainfall,
based on weather radar observations at Apalach-
icola and with the results supported by correspond-
ing studies at Tampa, showed that showers within
160 km of the radar installation were nearly as
frequent over the sea as over the land when aver-
aged over a 24-hour period (Smith 1970). This and
similar studies in south Florida (Frank et al. 1967)
found high numbers of showers over land in the
afternoon and low numbers in the early morning.
They found a minimum number over the sea in the
afternoon and a maximum during late night and early
morning, especially within 50 km of the coast.
When interpreting the rainfall data, it is important
to note that the start and end of the rainy seasons
may vary by 6 or 7 weeks from yearto year. As seen
in Table 1, the majority of thunderstorm activity
occurs during the summer.
Most of this summer rainfall occurs in the
afternoon in the form of often heavy local showers
and thunderstorms of short duration (1-2 hours) that
are on rare occasions during the spring
accompanied by hail. Summer rain which lasts for
longer periods is often associated with occasional
tropical disturbances. Winter rains are associated
with frontal systems and are generally of longer
duration than the summer rains, but are fewer in
number and have a slower rate of rainfall
accumulation. Hourly data taken at Tallahassee
beginning in the 1940's through the 1970's
demonstrate the different diurnal patterns of the
summer and winter rains (Figure 20). Snowfall
33
Panhandle Ecological Characterization
Figure 18. Panhandle average annual rainfall and NOAA climatological station locations (after Jordan
1984).
occurs at rare intervals across the Panhandle,
approximately 1 year in 10 for measurable falls, and
approximately 1 year in 3 for trace amounts (U.S.
Dept. of Commerce 1980a, 1980b, 1980c).
Despite large average annual rainfalls, droughts
occur (Figure 21). Even short periods of drought,
when combined with the reduced area of lakes and
wetlands and the low water table found during gen-
erally dry years, can cause extensive crop losses in
the agricultural areas, as well as increase damage
from forest fires. Fires during extended droughts can
cause severe damage even in the longleaf pine
areas adapted to seasonal fires and result in the
burning of parched wetlands and other habitats
normally protected from fire. These areas, not
adapted to the normal periodic fires of the pine forest,
may recover very slowly (Means and Moler 1979).
3.2.3 Winds
a. Normal wind patterns. From March through
September, the Panhandle is under the western
portion of the Bermuda high-pressure cell, which has
a general clockwise (anticyclonic) circulation of the
low-level winds (i.e., those measured at an altitude of
600-900 m) (Atkinson and Sadler 1970) (Figure 22).
The latitude at which the wind shifts from out of the
southeast to out of the southwest (the "ridgeline"-
shown by the dashed lines in Figure 22) changes
substantially during spring and summer. During
October through February, a western anticyclonic
cell separates from the Bermuda anticyclone and
establishes itself in the Gulf of Mexico (Figure 22).
The center of the cell migrates somewhat as indi-
cated by the X's, but generally results in low-level
winds from a westerly direction over the Panhandle.
These circulatory patterns indicate that the Pan-
handle is primarily influenced by tropical air masses
in the spring and summer and by continental (cold)
air masses during the fall and winter. The prevailing
winds in the Florida Panhandle are from a southerly
direction during the spring and summer (Figure 23).
Locally, wind directions may be determined by
3. Climate
Maximum Rainfall
over 12 Consecutive Months
ALABAMA
GEORGIA
'265
TOTAL CENTIMETERS RECORDED
1951- 1980 Data
Minimum Rainfall
over 12 Consecutive Months
S7*
-T--
860 S5.
ALABAMA
GEORGIA
TOTAL CENTIMETERS RECORDED
GULF OF MEXICO
GULF OF MEXICO
1951-1980 Data
Figure 19. Panhandle maximum and minimum 12-month rainfall (after Jordan 1984).
35
1 9 1---
Panhandle Ecological Characterization
Table 1. Panhandle thunderstorm frequency statistics (Jordan 1973).
Percent of Percent of
Mean annual days thunderstorms thunderstorms
with thunderstorms during June-Sept during Nov-Feb
Pensacola 65 65 12
Apalachicola 73 73 7
Tallahassee 79 70 6
6 12
PM Midnight
Figure 20. Percent of total daily rainfall during
individual hours of the day at Tallahassee (after
Jordan 1984).
thunderhead formation and thunderstorms. Wind
direction changes with the passing of each cold front;
most commonly these occur during the fall and
winter (September through March). As the front
passes through, the wind, which normally blows out
of a southerly direction, rapidly changes direction
with a clockwise progression ("clocks") through the
west, then pauses out of the northwest quadrant for
approximately 1-3 days, blowing toward the front
receding to the south or southeast. After the front
has passed a sufficient distance to allow the "normal"
wind patterns to reassert themselves, the wind
finishes clocking through the east and back to the
south. The directional orientation of the front and the
direction from which the wind blows immediately
following its passage depends upon the origin of the
front; the winds are from the north forfronts of Arctic
and Canadian origin, from the west to northwest for
those of Pacific origin.
This cycle is sometimes interrupted by the ap-
proach of a new cold front closely following the first.
t-
E
z
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
25 32 28 41 37 19 0 19 68 34 26 28
Longest dry period on record beginning In month indicated
20
S15-19 Days
Pensacola [ 2024 Days
0 >24 Days
15 .............. .... ...............
10 .............. ........... ......... .........
.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
27 24 28 30 29 26 18 26 49 36 23 23
Longest Dry Period On Record Beginning In Month Indicated I
Figure 21. Occurrence of extended dry periods
at Tallahassee and Pensacola, 1950-80 [no day
over 0.25 cm] (after Jordan 1984).
As a result, the most prevalent winds during Septem-
ber through February (the season of frontal pas-
sages) are out of the northern half of the compass
36
12
10 Dec-March
June-Sept
a 4
2
0
12 6 12
Midnight AM Noon
3. Climate
March-September
October-February
Figure 22. Low-level (600-900 m) winds (from Atkinson and Sadler 1970).
(following the fronts) with less frequent and weaker
winds from the southern half of the compass (before
the fronts) (Figure 24). The annual average resultant
wind (i.e., the vector sum of the monthly wind speed
and direction) in the Panhandle is from the north.
This is due to the greater wind speeds that follow the
winter fronts than blow during the rest of the year. All
of these wind patterns are somewhat erratic due to
convective forces inland and because of the result-
ing land- and sea-breeze mechanism nearthe coast.
The mean monthly wind strength is less in
summer months than during the fall, winter, and
spring (Figure 25). Since data for Pensacola were
unavailable, those for Mobile are included in the
figure. Inland stations exhibit somewhat lower
Panhandle Ecological Characterization
Tallahassee Pensacola
Spring (March-May)
Tallahassee
Pensacola
Summer (June-August)
Figure 23. Percentage of time wind blew from
different directions in Panhandle during spring
and summer, 1959-79 average (after Fernald
1981).
12
C-
C
" 4 .
4-
Tallahassee Pensacola
Fall (September-November)
Tallahassee
Pensacola
Winter (December-February)
Figure 24. Percentage of time wind blew from
different directions in Panhandle during fall and
winter, 1959-79 average (after Fernald 1981).
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Figure 25. Seasonal windspeed at sites in and near the Florida Panhandle (after Jordan 1973).
38
3. Climate
average speeds than those along the coast (Jordan
1973). The highest 1-minute sustained wind speed
is seldom over 50 km/h, though sustained non-hur-
ricane-associated winds in the 85-95 km/h range
have been recorded (Bradley 1972). These peak
sustained wind speeds are generally higher at the
eastern end of the Panhandle than at the western
end (U.S. Dept. of Commerce 1980a, 1980b, 1980c;
Fernald 1981).
b. Hurricanes, tornadoes, and waterspouts.
Hurricanes pose a major threat to the Florida Pan-
handle. A hurricane is a cyclonic storm (i.e., the
winds rotate counterclockwise in the northern hemi-
sphere) with sustained wind speeds in excess of 120
km/h. Forty-eight hurricanes have come ashore in
this region from 1885 to 1985. Figure 26 shows the
tracks for hurricanes hitting the Florida Panhandle
during this period while Table 2 gives their monthly
distribution.
Much of hurricane damage is caused bythe local
rise in sea level known as storm surge. For hurri-
canes striking the Panhandle from the gulf, this rise
occurs east of the "eye" (the storm's center) as the
counterclockwise wind circulation about the eye
pushes water ahead and traps it against the coast-
line. An embayment helps contain this water and can
increase storm-surge magnitudes substantially
when a hurricane strikes its western side. Tidal
stage and phase, bottom topography, coastline con-
figuration, and especially wind strength combine to
Figure 26. Paths of hurricanes striking the Panhandle coast, 1885-1985 (after Jordan 1984, Case
1985).
Panhandle Ecological Characterization
Table 2. Total number of hurricanes and tropical storms striking or passing within
150 miles of the Florida Panhandle during 1885-1985 (Jordan 1984, Case 1986).
Jun Jul Aug Sep Oct Nov-May Total
7 5 8 20 6 2 48
determine the storm-surge magnitude. The State of
Florida addressed coastal safety, property protec-
tion, and beach erosion during hurricanes in Hen-
ningsen and Salmon (1981).
Tornadoes and waterspouts form infrequently.
They occur most commonly in the spring, associat-
ed with frontal weather systems, and in connection
with tropical storms and hurricanes. Tornado paths
in Florida are usually short, and historically damage
has not been extensive. Waterspouts occasionally
come ashore but dissipate quickly after reaching
land and, therefore, affect very small areas (Bradley
1972).
3.2.4 Insolation
The amount of sunlight, or insolation, reaching
the Florida Panhandle directly affects temperature
as well as photosynthesis. It indirectly affects proc-
esses in which these factors play a role, including
weather patterns, rates of chemical reactions (e.g.,
metabolism), productivity, and evapotranspiration
(evaporation and water transpired into the atmos-
phere by plant foliage). The amount of insolation is
controlled by two factors: season and atmospheric
screening.
a. Seasonal changes. Seasonal insolation is
controlled by five factors: (1) the changing distance
between the Sun and Earth as Earth follows its
elliptical orbit; (2) the increasing thickness of the
atmosphere throughwhich the solar rays must travel
to reach the Earth's surface at points north or south
of the orbital plane (Figure 27); (3) the reduced
density of rays striking an area on Earth's surface
north or south of the orbital plane (Figure 28); (4) the
changes in cloud cover associated with the progres-
sion of the seasons; and (5) seasonally induced
changes in atmospheric clarity due to particulates.
Factors 2 and 3 are caused by Eath's axial tilt
relative to the orbital plane and the resultant change
Light path in high latitudes
_.. ...
Earlh '
Figure 27. Change in length of atmospheric light
path with change in distance above or below
orbital plane.
Figure 28. Change in light intensity at Earth's
surface with change In distance above or below
orbital plane.
3. Climate
in the angle at which solar rays strike a point on the
globe during Earth's year-long trip around the sun.
This change alters the distance through the atmos-
phere that the rays must travel and, therefore,
changes the percentage of the rays reflected or
absorbed by the atmosphere. Factors 4 and 5 are
products of seasonal variations in insolation upon
circulation of air masses, hence the effects from
insolation affect the amount of it reaching the Earth's
surface. The concentration of screening particulates
in the atmosphere is further affected by seasonal
variations in emissions resulting from human activi-
ties (e.g., smoke from heating during winter) and by
the variations in the speed with which both natural
and anthropogenic particulates are removed by rain-
fall or diluted by atmospheric circulation.
b. Atmospheric screening. Absorption or re-
flection by water vapor, clouds and atmospheric
particulates such as dust and smoke effectively
reduce the solar radiation penetrating to the Earth's
surface. On a clear day approximately 80% of the
solar radiation entering the atmosphere reaches the
Earth's surface. About 6% is lost because of scatter-
ing and reflection and another 14% from absorption
by atmospheric molecules and dust. During cloudy
weather another 30/-60% may reflect off the upper
surface of the clouds and 5/%-20% may be removed
by absorption within the clouds. This means that
from 0%to 45% may reach Earth's surface (Strahler
1975). Thus it is clear that the single largest factor
controlling short term insolation is cloud cover.
The percentage of cloud covervaries seasonally
(Figure 29), as do the patterns of cloud cover. The
seasonal patterns of cloudiness are controlled pri-
marily by extratropical cyclones and fronts in the
winter, and by localized convective weather patterns
in the summer. Though the types of clouds and
rainfall patterns are different under each of these
systems, they result in similaramounts of cloudiness
and rainfall in winter and summer in the Panhandle.
Daily cloud cover variations are considerably greater
in winter than in summer. That is, in summer many
days have partial cloudcoverwhile inwinterthe days
tend to be entirely overcast or entirely clear. In south
Florida, where winter cyclones and fronts are less
frequent, the winter and summer amounts differ
greatly.
The maximum insolation striking Earth's atmos-
phere at the latitude of Panhandle Florida is approxi-
mately 925 langleys/day (Strahler 1975). Figure 30
shows the seasonal variation of the daily insolation
[ Apalachicola
80- .................................................................... Pensacola ..
U Tallahassee
Tallahassee Satellite
60-
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Figure 29. Mean daytime sky cover (data from U.S. Dept. of Commerce 1980a,b,c) and Tallahassee
cloud cover from 3 years of satellite data (after Atkinson and Sadler 1970).
Panhandle Ecological Characterization
1100
1000
900
800
700
600
500
400
300
200
100
spring
equinox
summer
solstice
fall
equinox
winter
solstice
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 30. Variations in insolation striking the atmosphere depending on latitude and season (after
Strahler 1975).
striking the atmosphere over the Panhandle region.
The monthly average of the daily insolation amounts
actually received at Tallahassee and Apalachicola
are presented in Figure 31. In addition, the percent
of possible sunshine measured at Tallahassee and
Pensacola is presented in Figure 32.
Atmospheric clarity over the Panhandle is, with
the exception of clouds, generally very good. Occa-
sional atmospheric inversions during summer
months may result in "haze" as natural and anthropo-
42
genic aerosols are trapped near the surface and
concentrated, thereby reducing insolation.
3.2.5 Relative Humidity
The Florida Panhandle is an area of high relative
humidity. Relative humidity is the amount of water
vapor in the air, expressed as a percent of saturation
at any given temperature. Air incapable of holding
further water vapor (saturated) has a relative humid-
ity of 100%. The amount of water necessary to
saturate a volume of air depends upon temperature.
3. Climate
800.
E3 Apalachicola
STallahassee
400. ..... ......
f 200.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Figure 31. Monthly insolation at selected sites in
Florida Panhandle (after Bradley 1972).
Air at a higher temperature is capable of holding
more water than that at a lower temperature; there-
fore, air near saturation will become oversaturated if
cooled. This oversaturation can produce dew, pre-
cipitation, or, when very near saturation, clouds or
fog. In the seasons when prevailing winds bring
moist air from the Gulf of Mexico (i.e., spring, sum-
mer, fall), humidity is often 85%-95% during the
night and early morning, and 50%-65% during the
day (Bradley 1972).
High relative humidity can greatly accentuate
the discomfort of high summer temperatures. There
are several formulas commonly in use (e.g., Tem-
perature Humidity Index, Humidity Stress Index,
Humiture) that generate a "comfort" value based
upon a combination of temperature and humidity.
The afternoon Panhandle climate during June
through September is usually well into the uncom-
fortable zone. These indices are based on the effect
of humidity upon evaporation rates. The humid air
flowing from the Gulf of Mexico has minimal capacity
to hold further moisture. As a result, evaporative
drying of wetlands and other water bodies in the
Panhandle is minimized, thereby helping to maintain
them between rains. Summer rains and slow evapo-
ration also provide ideal conditions for many fungal
and bacterial diseases, prominent problems in area
farming (Shokes et al. 1982).
Fog is common at night and in the early morning
hours as the ability of the cooling air to hold water
decreases and the relative humidity rises over
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Figure 32. Percent of possible sunshine at se-
lected sites in Panhandle (data from U.S. Dept. of
Commerce 1980a,b,c).
100%. Heavy fogs (visibility < 0.4 km) generally form
in the late fall, winter, and early spring. On the
average, they occur 35-40 days per year (Bradley
1972). Apalachicola experiences fog on an average
of 14% of the days in November through March, and
2% of the days from April through October (Jordan
1973). Fogs usually dissipate soon after sunrise.
3.3 Effects of Climate on Ecosystems
Climate exerts control on the regional ecology
through two major mechanisms. The normal clim-
ate of the Panhandle establishes the basic condi-
tions under which all species must be able to live and
compete if they are to find a niche in the ecosystem.
The occasional abnormal or extreme climatic condi-
tion may prevent establishment of a species that
would otherwise thrive by producing periodic local
extinctions or near-extinctions. The rare severe or
prolonged freeze, heat wave, drought, or flood may
decimate a population so that years or decades are
required for its reestablishment.
No clear separation exists between conditions
constituting normal and extreme climatic conditions.
Regular events which are beyond a species' ability to
adapt may reduce what would otherwise be a domi-
nant organism to a minor position in the ecosystem
or prevent its establishment altogether. A Pan-
handle example is the mangrove. A dominant spe-
cies on Florida's southwest coast, mangroves are
represented in the Panhandle by one small colony of
43
Panhandle Ecological Characterization
black mangrove on the bay side of the eastern end
of Dog Island. In conditions otherwise conducive to
mangrove growth, the occasional cold winters limit
them to this marginal colony. In contrast, an other-
wise minor organism may be dominant through its
ability to survive the climatic extreme and thereby
outcompete ecological rivals. Relatively small
changes in the "normal" extremes of climate may
produce effects on ecosystem composition as large
as those produced by changes in the average cli-
mate. An example might be a situation where a slow-
growing and reproducing shrub species and a fast-
growing and reproducing shrub species compete for
space in a forest clearing commonly visited by forag-
ing wild pigs. All otherfactors being equal, the slow-
growing species might dominate, even though it
would be very slow to recolonize areas where it was
dug up by the pigs, because it could better tolerate
the annual dry summers. An increase in the normal
summer rainfall (a change in the "average climate")
might leadto dominance of the fast-growing species.
The same effect might result, however, if the area
began to experience previously unknown hard
freezes during occasional winters (a change in the
climatic extremes), and the slow-growing species
was killed by freezes while the fast-growing species
was freeze tolerant. Either change will have the
greatest effect upon those organisms living near
their limits of tolerance.
3.4 Major Influences on Climate
3.4.1 Natural Influences on Climate
a. Long-term Influences on climate. Long
term changes (overthousands to millions of years) in
worldwide climate are primarily a function of
changes in the concentration of atmospheric carbon
dioxide (CO,) (Revelle 1982). Carbon dioxide traps
incoming solar radiation (Hansen et al. 1981). This
effect is commonly known as the "greenhouse ef-
fect." The resulting temperature increase allows the
atmosphere to hold more water vapor, itself an
effective greenhouse gas, which accentuates the
warming. Othergases (e.g., methane, nitrousoxide,
chlorofluorocarbons) act similarly, but their effects
are generally subordinate to those of CO because of
their relatively low concentrations. The Sun "drives"
Earth's climate since the wind and rain systems, as
well as the temperature regime, are products of
varying insolation.
b. Short-term Influences on climate. Short-
term (upto hundreds of years) naturalfluctuations in
climate are generally caused by changes in insola
tion screening. The concentration of natural atmos-
pheric particles results from the balance between
input from wind scouring (particularly of desert and
otherarid regions), volcanic dust output, smokefrom
forest fires and volcanoes, and removal by gravita-
tional settling and atmospheric scrubbing during
rainfall.
The Panhandle, along with the rest of the north-
ern temperate lands, has experienced an approxi-
mately 0.1 oC reduction in average temperature over
the last decade despite an increasing greenhouse
effect worldwide. It is probable that this is the result
of: (1) the screeningof insolation atthese latitudesby
increased atmospheric smoke and dust from recent
increased volcanic activity and/or dust from the
expanding Sahara desert and drought areas in North
Africa, and /or (2) variation in the Sun's output
(Hoffman et al. 1983). These variations are histori-
cally common and Titus and Barth (1984) concluded
that they were incapable of overwhelming the overall
greenhouse effect.
Periodic changes in climate and weather affect-
ing the Panhandle have recently been tied to the
phenomenon known as El Nino. Though all the
parameters of cause and effect are not yet under-
stood, a major current off the coast of Peru, which
drives the upwelling responsible for one of the
world's largest fisheries, apparently moves well off-
shore and weakens because of changes in the wind
patterns driving it. Changes in equatorial wind pat-
terns which eithercause the shift in watercurrents or
are caused by the shift (which factors are cause and
which are effect are not yet understood) affect world-
wide climate by altering patterns of rain, tempera-
ture, and wind. The Panhandle may have just
recovered from a period of weather in the early
1980's influenced by an exceptionally strong El Nifo.
The hotter and drier summers and warmer winters
followed by a rebound period of spring flooding,
heavy summer rainfall, and colder winters that have
been experienced in the Panhandle and other
44
3. Climate
unusual weather patterns worldwide have been
tentatively identified as indirect effects of El Nino.
Another mechanism controlling short-term cli-
mate changes as well as being involved in long term
variations is albedo, or the reflectance of a surface.
The higher the albedo, the more incoming radiation
is reflected and can pass through the "greenhouse"
gases and out of the atmosphere. The lower the
albedo, the more radiation is absorbed, reradiated
as heat and trapped in the atmosphere. Snow and
ice have a very high albedo; i.e., they are efficient
reflectors of solarenergy (45/%-85%). Bare ground,
fields and forests have intermediate albedos ranging
from 3%-25%. Unlike land, the oceans (and water
in general) have a variable albedo; very low (2%) for
radiation striking from low angles of incidence (i.e.,
with the sun high in the sky), but high forthat striking
from high angles (i.e., with the sun low on the
horizon). This is caused by the growing proportion of
the light that is transmitted into the water at decreas-
ing angles of incidence. Thus the equatorial seas at
midday are good absorbers of solar energy, but the
arctic seas are not. The significance of this in the
Panhandle is that coastal waters receive more heat-
ing through insolation in summer, not only because
of the increase in sunlit hours from the longer day,
but also from an even greater increase of the time the
radiation strikes from high angles. Other local ef-
fects of albedo differences are common, as anyone
who has stood on an asphalt parking lot on a clear
summer day can attest.
Another difference between the effects of inso-
lation on land and water is caused by the difference
in the specific heat of dry soil or rock and that of
water. Water requires nearly five times as much heat
energy as does rock to raise its temperature the
same amount. This, coupledwith the increased eva-
porative cooling found at the surface of water bodies,
explains the more extreme diurnal and seasonal
temperature regimens found over land as compared
to that over or near large bodies of water.
3.4.2 Anthropogenic Influences
Human activities increasingly influence climate,
although the line dividing natural and anthropogenic
influences is not always clear. Global warming due
to changes in the atmospheric greenhouse effect is
one of the most notable results of human activities
(Hansen et al. 1981, Weiss et al. 1981, Broeckerand
Peng 1982, Edmonds and Reilly 1982). This change
is primarily a result of increasing concentrations of
atmospheric carbon dioxide from combustion of
fossil fuels as well as from the logging of enormous
areas of forest, with the resultant release of CO,
through the burning or decomposition of the carbon
bound up in the organic matter (Chamey 1979); of
atmospheric methane (Rasmussen and Khalil
1981a, 1981b, Kerr 1984); of atmospheric nitrous
oxides (Donner and Ramanathan 1980); and of
chlorofluorocarbons (Ramanathan 1975). There
was a 9% increase in atmospheric carbon dioxide
between 1958 and 1985 (Figure 33).
A conference was held in 1982 in response to
articles in popular literature (Boyle and Mechum
1982) concerning a theory ascribing recently re-
duced rainfall and increased temperature in south
Florida to reduced albedo and evapotranspiration
resulting from the draining of area wetlands. The
results of this conference are summarized in Gan
non (1982). Though evapotranspiration from land
masses may account foronly 5% ofthe precipitation
in south Florida (the bulk arriving with air masses
fromoverthe Atlantic), evapotranspiration increases
the buoyancy of the continental air masses. It is
probable that this increases mass convergence,
bringing in more moisture from the adjacent oceans
and acts as a trigger to increase convection and,
therefore, the convection-induced rains. Rainfall of
this nature is found year round but is especially
common in summer. A 70 inch rainfall deficit which
accumulated between 1962 and 1982 along the St.
Johns River in northeast Florida has also been
attributed to the draining by 1972 of approximately
72% of the once vast wetlands through which the
river flowed (Barada 1982). If this relationship be-
tween evapotranspiration and rainfall is confirmed, a
similar mechanism probably exists in the Pan-
handle, where similar patterns of convective rainfall
are found. Future development which reduces
wetland and vegetated areas might induce similar
reductions in summer rainfall.
Short-term cooling trends have been attributed
to insolation screening by dust, smoke, and debris
thrown into the upper atmosphere by large volcanic
eruptions such as Krakatoa in 1883 (Humphries
1940) and Mount St. Helens in 1980 (Searc and Kelly
Panhandle Ecological Characterization
1958 1962 1966 1970 1974 1978 1982
Figure 33. Increasing atmospheric carbon dioxide as measured atop Mauna Loa, Hawaii (data from
Charles Keeling, Scripps Inst. of Oceanography).
1980). Smaller eruptions have a weaker cooling
effect. It is thought that this short-term cooling may
be partially masking the long-term global warming
caused by increasing concentrations of atmospheric
CO, (Bell 1980).
3.5 Summary of Climatic Concerns
The Florida Panhandle has three present and
near-future climatological concerns. Two of these
result from the present global warming trend. While
all effects of this warming are not predictable with our
present understanding of the ecosystem, certain
effects in the Panhandle are probable. A major
impact resulting from global warming is a predicted
substantial rise in sea level, significant effects of
which are expected within 25 years. This impact is
discussed more fully in section 4.8. The second
concern relating to atmospheric warming is a prob-
able change in weather patterns A possible 5 F
increase in the mean global temperature bythe latter
part of the next century is projected to yield a similar
increase in mean Panhandle temperature and a few
percent increase in local precipitation (Revelle 1982,
National Research Council 1983). The present
understanding of meteorology is not, however, suf-
ficientto permit reliable prediction of these changes.
This is particularly true of climate changes over a
relatively small area the size of the Panhandle.
A final climatic concern for the future is the
possibility of reduced summer convectivee) rainfall.
Unlike the previous two problems, the causes have
not yet been widely initiated and are preventable.
Convective summer thundershowers provide the
majority of summer rainfall. Summer rains, in turn,
supplythe majority of the total annual rainfall (Figure
17). The convective mechanism causing these rains
is similar to that found in south and east Florida.
Since the "rain machine" in these regions may have
been weakened by extensive wetland draining, it is
possible that future terrain alteration in the Pan
handle-including drainage and development of
large wetland areas--could cause a similar effect.
3. Climate
Predicting the occurrence and effect of climate
changes is very difficult since the understanding of
the meteorological and oceanographic systems that
provide climatic feedback and checks-and-balances
is incomplete. With these constraints, even the sea
level predictions, which are based on an intensive
program of study, include necessarily wide margins
for error. Unexpected or unexpectedly strong feed-
back mechanisms may exist to damp the warming
trend. One possible example of such feedback is
that the increase in size taking place in our deserts
(especially the Sahara) may be a result of global
warming; however, the increased dust blown intothe
atmosphere from the larger desert area may be
increasing insolation screening and therefore tend-
ing to reduce that warming. The possible existence
and "strength" of similar feedback mechanisms
make accurate prediction of future climate difficult;
however, the National Academy of Sciences
(Charney 1979) was unable to find any overlooked
physical effect that could reduce the estimated
temperature increase to negligible proportions. The
accuracy of the predictions is increasing through
research into the major climatic factors.
3.6 Areas Needing Research
Research on numerous aspects of the Panhan-
dle climate is needed concerning questionswhich, of
course, affect much wider areas, but are applicable
to this area Research is especially needed on the
changing greenhouse effect; the effects of increas-
ing world-wide average temperatures on area cli-
mate; the mechanisms controlling coastal convec-
tive rainfall; and ratesof evapotranspiration andtheir
connection to rainfall and runoff.
Chapter 4. HYDROLOGY AND WATER QUALITY
4.1 Introduction
Water quality is, in many ways, dependent on
hydrology and frequently the forces affecting one
also affect the other. This chapter will discuss each
of these areas, their interrelationships, and their
status inthe Florida Panhandle. An excellent source
of general information on the water resources of the
Panhandle and all of Florida is the Water Resources
Atlas of Florida (Fernald and Patton 1984). The
Hydrologic Almanac of Florida (Heath and Conover
1981) has very good discussions of different hydro-
logic and water quality factors as well as containing
good, if occasionally dated, records on Florida.
Panhandle surface water supplies and its
ground water supplies are normally inseparable. In
many places water flows from the surface into the
ground and back again many times as it makes its
way to the coast. Any changes in the hydrology or
the quality of one is likely to affect the other. The
entire supply of potable ground water in Floridafloats
on deeper layers of saline groundwaterthat arecon-
nected with the Atlantic Ocean and the Gulf of
Mexico. This layerof fresh waterfloats because it is
-2.5% less dense than the salt water. As water is
removed from the fresh-water aquifer, the under-
lying salt watertends to pushthe uppersurfaceofthe
fresh-water aquifer higher as the aquifer gets lighter.
As a result, "permanently" lowering the upper sur-
face of the freshwater aquifer by 1 ft over a broad
area requireswithdrawing avolumeofwaterequalto
nearly 40 ft of the aquifer thickness. Thus, simplis-
tically, for every foot our pumping of the fresh-water
aquifers lowers the uppersurface and is not replaced
in a reasonable period of time by rainwater, the
deeper saline layers rise 40 ft. The Florida Pan-
handle, and all of Florida, has tremendous volumes
of fresh water stored beneath the ground; however,
it cannot be used at a rate greater than the average
rate at which i is replaced by rainfall. Otherwise,
saltwater intrusion will render the coastal wells use-
less because the depth to the underlying saline layer
is much less near the oceans.
4.1.1 Hydrology
Hydrology is the study of the water cycle, includ-
ing atmospheric, surface, and ground waters. The
basic hydrologic cycle (Figure 34) includes water
vapor entering the atmosphere as a resultof evapo-
ration, transpiration, and sublimation. This vapor
condenses to form fog, clouds, and, eventually,
precipitation. In the Florida Panhandle precipitation
normally reaches the ground in the form of rain.
Snow and hail occur infrequently. Upon reaching the
ground, the water either evaporates, soaks into the
soil and thence into the groundwater system, or (if
the ground is saturated orthe rate of rainfall exceeds
the ground's ability to absorb it) runs off or pools,
forming streams, rivers, lakes and other wetlands.
The fundamental organizational unit of surface
hydrology is the drainage basin. In its most basic
form, drainage basin, orwatershed, consistsofthat
area which drains surface runoff to a given point.
Thus the mouth of a river has a drainage basin that
includes the basins of its tributaries. The drainage
areas discussed in this document are based upon
the basins described by the U.S. Geological Survey
(Conover and Leach 1975) (Figure 35). Most of
these consist of the Florida portion of the drainage
basin of a single coastal river. A large portion of
many of these basins actually extends well into
Georgia and Alabama (Figure 36). Some, however,
represent coastal drainage areas where lands drain
to coastal streams and marshes on a broad front
rather than to a single discharge point.
Figure 34. The basic hydrologic cycle.
Panhandle Ecological Characterization
ALABAMA
_H 7 -7 /
K A
', / I
i ...JAcK~;cNN
-- -si
-.-
~~~~~7 .6 fZIGy
GEOR
GULF OF MEXICO
0 10 20 30 40 50
1 11 Miles
A. Ochlockonee River
B. Coastal area between Ochlockonee
and Apalachicola Rivers
C. Apalachicola River
Chipola River
St. Andrew Bay
Choctawhatchee River
Choctawhatchee Bay
Yellow River
Blackwater River
Escambia River
Escambia Bay
Figure 35. Panhandle drainage basins discussed in this document (after Conover and Leach 1975).
Ground water in the Florida Panhandle is con-
tained primarily within two overlapping reservoirs:
the Floridan aquifer underlying the entire Pan-
handle; and the Sand and Gravel aquifer which
overlies the Floridan west from Okaloosa County
(Figure 37). A shallow surficial aquifer is found
overlying the Floridan aquifer in many parts of the
eastern Panhandle (Figure 38).
Panhandle aquifers are recharged by five
means: (1) drainage of surface runoff into areas
where the aquifer is unconfined (i.e., not overlain
with a low-permeability stratum) and located at or
near the ground surface; (2) drainage of surface
runoff into sinkholes and other natural breaches into
the aquifer; (3) percolation of rainfall and surface
water through the upper confining beds; (4) percola-
tion through the confining layers of water from aqui-
fers overlying or underlying the one in question but
with a greater potentiometric surface ("pressure");
and (5) lateral transport from areas within the aquifer
with a higher potentiometric surface (Figure 39).
Areas within the Panhandle recharging the Floridan
aquifer are presented in Figure 40.
4.1.2 Water Quality
The availability of water has always been an
important factor in selection of sites for human activi-
ties. The primary concern of the past-securing
needed quantities of water-has, in recent years,
increasingly been replaced by concerns about the
quality of that water. Water quality affects people
directly by influencing water's suitability for drinking,
cooking, bathing and recreation, and indirectly by its
effect upon the ecosystem within which humanity
exists. Factors affecting water quality include the
physical makeup of the local ecosystem (e.g., the
presence of limestone generally prevents acidic
water), seasonal changes in that ecosystem, direct
discharges from human sources, and indirect dis-
charges from human sources (e.g., acid rain).
Society judges water quality based upon its
usefulness to people and those animals and plants
50
N
4. Hydrology and Water Quality
N
GEORGIA
GULF OF MEXICO
0 10 20 30 40 50
i I- I jMiles
Figure 36. Out of state drainage basins of Panhandle rivers (after
51
ALABAMA
Panhandle Ecological Characterization
ALABAMA
V. L Taft
I nG
. .I..- ,
CI.o,,oo
GULF OF MEXICO
\I~J y
GEORGIA
--' I. II ", ' *'
:,~" ^ J^"' ^:
T / .
L.-' _
- e- S. -
0 10 20 30 40 50
1 _l Miles
Figure 37. Primary Panhandle aquifers used as water sources (after Hyde 1975).
Cross Section
West-East Hydrologic Cross Section
North-South Hydrologic Cross Section
7-- h Upper Floridan se -
Aquifer level
I
Lower Floridan -200
Surficial Aquifer Aquifer W 00
Sand and Gravel
Aquifer
Intermediate
Aquifer (confining
layer)
Calhoun Co
Gulf Co
Lower Floridan
SConfining Unit
SI Bucatunna Clay
Confining Unit
Z 0 10 20mi
Figure 38. Hydrologic cross sections of the Panhandle (after Wagner et al. 1984).
200-
sea-
level
-200-
400-
800-
1200-
1600-
west
86" 850 8gV
f
F
~3 "
o A J,
4. Hydrology and Water Quality
ALABAMA
' GEORGIA
GULF
OF
"MEXC
0 10 20 30 40 50 Miles
I I I I I
UNITS IN FEET
Figure 39. Potentiometric surface of the Floridan aquifer in the Panhandle in May, 1980 (after Healy
1982).
870 86. 850 840
--- ALABAMA
/OKALOO&A .' D7-
WAKULLA
N GULF OF MEXICO -R \i : -
0 10 20 30 40 50
' 1 Miles
\ Generally No Recharge Natural discharge areas. Heavy pumpage may reverse gradient and induce limited local recharge.
SKnown Very Low Recharge Floridan known to be overlain by relatively impermeable and unbreached confining beds.
Very Low to Moderate Recharge Floridan overlain by thinner or breached confining beds; water table higher than potentiometric surface.
S High Recharge Well-drained upland areas characterized by poorly developed stream drainage systems.
Figure 40. Recharge areas to the Floridan aquifer in the Panhandle (after Stewart 1980).
53
Panhandle Ecological Characterization
we value. Since our society has come to recognize
the value of a healthy ecosystem, we try to measure
this health in addition to the physical and chemical
water quality parameters. Increasingly this is done
by examining the number and diversity of the spe-
cies and individuals present in the water body.
Various indices have been developed and used
including numerous species diversity indices and
what are known as biotic indices, which measure the
presence of key species judged to be indicators of
high water quality. Combinations of these indices
aid in quantifying the degree of ecological health, but
results from any one index must be viewed with cau-
tion. Each method, because of the manner with
which it weighs different factors, generally has situ-
ations in which it gives a poor representation of the
actual conditions.
a. Direct importance. The first concerns about
water quality were directed toward the transmission
of disease through drinking water. Eventhisconcern
is relatively new, The desirability of separating
human wastes from sources of waterfordrinking and
food preparation was not understood in western
civilizations until the mid-1800's and this separation
was not effected on a wide scale until the early
1900's.
Until the early 1970's, drinking water was rou-
tinely examined and treated primarily for disease
pathogens. Only recently has an awareness of the
health and environmental impacts of toxicants be-
come widespread The majority of these substanc-
es are metals or synthetic organic compounds.
Metals from natural sources in sufficient concentra-
tions to cause problems are uncommon. Most of the
organic hydrocarbons contaminating waters do not
occur naturally. The vast majority of toxic sub-
stances found in the planet's waters are anthropo-
genic, products of modern industrialized society.
Efforts to locate, identify, and remove these
substances from our waters are greatly hindered by
their enormous number and variety, their difficult
detection, and the lack of knowledge concerning
both their short- and long-term effects. Some are
toxic at levels below which their concentrations can
be reliably measured. Increasing the problem of
controlling these hazards is the daily discovery or
synthesis of additional chemical compounds, many
of which are a potential threat to water supplies. In
addition to exposure through contaminated drinking
water, some of these substances are being found in
human foods following uptake by food plants or
animals.
A secondary problem is the need for water of
sufficiently high quality to meet industrial needs.
Though most industrial water uses are for cooling,
steam generation, materialtransportation, and simi-
lar tasks not requiring potable water, preventing
scale buildup in steam and cooling equipment and
using water for product makeup and certain chemi-
cal processes may require that specific aspects of
the water quality be high.
b. Indirect Importance. The quality of water,
boththe physical characteristics and the presence or
absence of toxic components, is a factor controlling
ecosystem constituents (e.g., productivity, species
diversity). Just as climate and water availability exert
control upon floral and faunal composition, so does
the quality of the available water. An area of poor
water quality may support little or no life or, alterna-
tively, populations of undesirable species.
Humanity is at the apex of a food web pyramid
and is, therefore, dependent upon the soundness of
the base of that pyramid for existence. If pressed, we
may be capable of treating sufficient quantities of
contaminated water to supply humanity's direct
water needs; however, water of the quality neces-
sary to support all levels of the ecosystem must be
available, otherwise the food web pyramid may
erode from beneath us.
4.1.3 Hydrology and Water Quality Regulation
and Management
Though attempts are being made to treat drink-
ing waters for contaminants, the removal of contam-
inants from the natural surface waters to which
people are exposed during work or recreation is
much more difficult to manage. It is impractical to
treat surface waters to remove contaminants or alter
physical parameters; rather, contaminant removal
and physical changes must be performed prior to
discharge of domestic or industrial effluents. To this
end, State and Federal regulations have been en-
acted in an attempt to control effluent discharges into
surface waters. Underthe Federal Clean WaterAct,
4. Hydrology and Water Quality
point source discharges into surface waters of the
United States are regulated by the National Pollutant
Discharge Elimination System (NPDES). Underthis
system dischargers are given permits to discharge
effluents meeting certain standards based upon the
types of waste generated. The discharger is re-
quired to monitor the effluents and report periodi-
cally. In Florida, all NPDES permit applications and
reports are reviewed by the Florida Department of
Environmental Regulation (FDER). Under NPDES
regulations, effluents should meet State water qual-
ity standards. The NPDES program, however, does
not regulate dischargers in such a way that cumula-
tive impacts are controlled. Hence, while a river may
have numerous discharges into it, each meeting
water-quality standards, the cumulative effect of all
the discharges upon the river may cause its water
quality to fail to meet standards. The NPDES pro-
gram primarily is aimed at conventional pollutants,
including bacteria, nutrients, and materials decreas-
ing dissolved oxygen (DO) concentrations.
Surface waters have been monitored by the
FDER since 1973 using Permanent Network Sta-
tions (PNS), though this monitoring network has
been substantially reduced in recent years. The
responsibility for management of regional water
resources is held by the Northwest Florida Water
Management District (NWFWMD). This respons-
ibility includes regulation of water consumption and
long-range planning to help ensure the continuing
availability of high quality water. The water manage-
ment district also has its own network of monitoring
stations. At the request of the State Legislature, the
NWFWMD in 1979 formulated a water resources
management plan (NWFWMD 1979a) and a re-
gional water supply development plan for the Pan-
handle coast (Barrett, Daffin and Carlan, Inc. 1982).
Waste load allocation studies have been per-
formed by the FDER and, in earlier years, the U.S.
Geological Survey to attempt to determine the
amount of effluent discharges, including those of
sewage treatment plants and private sources, that
can be discharged into water bodies without degrad-
ing them. It should be pointed out that present
methods of wasteload allocation rely primarily on
models of DO and nutrient concentrations, are
aimed at allocation of nutrient loads from public and
private sources to maintain DO levels necessary for
a healthy aquatic system, and are therefore inca-
pable of predicting or allowing for effects from toxic
discharges. The FDER conducts a program of acute
and chronic toxicity bioassay testing on selected
private and municipal effluent discharges that are
recommended to them. Results of the tests are
available as reports from the FDER Biology Section,
Tallahassee.
Primarily because of cost considerations, most
data collected from the various monitoring networks
and stations is physical or chemical in nature. The
biological baseline studies and monitoring neededto
enable accurate determination of the overall "good-
ness" of the water quality of a particular water body
is generally lacking. Additionally, all the large Pan-
handle rivers are interstate rivers originating in
Georgia or Alabama. Thus, their hydrology and
water quality is influenced by factors outside their
Florida drainage basins. With the notable exception
of Apalachicola Bay, data limitations dueto changing
sampling methods and uncharacterized ambient
conditions have prevented long-term trend analysis
inthese riverbasins(FDER 1986c). Lackof baseline
data in most instances and lack of continuing data
collection in many instances prevent accuratedetec-
tion of changes in surface-water quality and hinders
interpretation of data gathered in short-term studies
and laboratory simulations performed to predict ef-
fects on area ecology (e.g., chronic toxicity bio-
assays) (FDER 1985a, Livingston 1986a).
Following the discovery in the early 1980's of the
toxic pesticides aldicarb (Temik*) and ethylene di-
bromide (EDB) in Florida ground waters, the Florida
Legislature passed the Water Quality Assurance Act
of 1983 which included steps to address the ground-
water contamination problem. One major aspect of
this act was the institution of a ground-water quality
monitoring networkto be administered bythe FDER.
This consists of a network of existing wells plus new
wells where existing ones are insufficient to permit
adequate ground-water sampling,each sampled on
aregularbasis. In its first phase, nearing completion
at the time of this writing, the FDER's Bureau of
Ground Water Protection performed extensive
chemical testing of ground-water samples as a pilot
operationto establishthe necessary locations forthe
monitoring wells, to gather mapping and water qual-
ity information (aquifer locations and water flow,
Panhandle Ecological Characterization
areas of saline intrusion, ambient ground-water
chemistry), and to help locate the main areas with
water quality problems. Upon completion of this
step, the preliminary locations of permanent moni-
toring wells and the frequency of sampling needed
will be determined. The ensuing program will be
altered as dictated by sampling results. The ground-
water monitoring network was envisioned as the
source of a computerized data base helping to (1)
determine the quality of water provided to the public
by major well fields in the state, (2) determine the
background or unaffected ground-water quality, and
(3) determine the quality of ground water affected by
sources of pollution. A biennial report describing
Florida's ground-water quality will be made available
to the public and governmental bodies to help in
decision making.
4.2 Water Quality Parameters
4.2.1. Dissolved Oxygen
a. DO capacities. The amount of oxygen dis-
solved in water can be a limiting factorfor aquatic life.
Dissolved oxygen levels below approximately 3-4
ppm are insufficient for many species to survive.
Alternatively, supersaturated levels of DO can result
in embolisms (bubbles forming within the animal's
tissues) and death. The amount of oxygen neces-
sary to saturate water is temperature dependent.
Higher temperatures reduce the saturation concen-
tration (amount of oxygen the water can hold) and
lower temperatures increase it (Figure 41). At 2 OC,
16-
m14- Oppt
E .- 35 ppt
_12
.10
C 8-
4
0 10 20 30 40 50
Temperature (oC)
Figure 41. Oxygen solubility as a function of
temperature.
freshwater (at sea level) is saturated at a DO of 13.8
ppm. At 30 OC, saturation occurs at 7.5 ppm.
Another major factor influencing saturation levels is
salinity; high salinities reduce saturation concentra-
tions and low salinities increase them (Figure 42).
While freshwater at 2 OC is saturated at 13.8 ppm,
seawater (35 ppt) at the same temperature is satu-
rated at 9.9 ppm. To provide a clearer picture of the
ability of a water body to absorb more oxygen, the
concentration is sometimes expressed as percent
saturation-the percentage of that DO concentra-
tion at which the water would be saturated.
b. Oxygen uptake-respiration. As a result of
these factors, during hot weather, when the meta-
bolic rates of aquatic lifeforms are highest and their
oxygen demands greatest, the oxygen carrying
capacity of water is lowest. This situation is accen-
tuated in confined water bodies, such as canals,
where poor circulation minimizes aeration and
maximizes water temperature.
The problem of the reduced oxygen capacity of
warm water is compounded by two factors: algal
respiration and biochemical oxygen demand (BOD).
"Fish kills" caused by low DO (which may include
many organisms other than fish) generally occur at
night or during periods of cloudy weather. The net
oxygen production by the algal population during
sunlit hours changes to a net oxygen consumption
during dark hours when algal photosynthesis ceases
but respiration by the algae and other sources con-
tinues.
16-
io-
-
>1 8-
0
0 10 20 30
Salinity (ppt)
40 50
Figure 42. Oxygen solubility as a function of
salinity.
56
b .
200C
4. Hydrology and Water Quality
c. Oxygen uptake-Biochemical Oxygen De-
mand (BOD). BOD results from microbial and
chemical consumption of oxygen during the degra-
dation of organic compounds in the water column
and bottom sediments. BOD becomes a problem
when excessive organic wastes enter an aquatic
system. Oxygen uptake from high BOD can reduce
DO levels to nearzero. Even relatively low levels of
BOD can contribute significantly towards low DO
levels and resulting problems i that BOD combines
with floral and faunal respiration and temperature-
salinity interactions. As a result, fish and inverte-
brate kills from low DO are not uncommon, espe-
cially during summer months. Most of the oxygen
dissolved in water results from gas exchange with
the atmosphere except during periods of heavy algal
growth. The rate at which a water body absorbs
oxygen from the atmosphere is influenced by its
circulation. If the oxygen must diffuse through the
entire watercolumn to reoxygenate depleted bottom
waters (i.e.,the water body is stagnant) then this rate
is very slow. Bottom waters in canals and other
enclosed water bodies, particularly those with a high
ratio of depth to width and having organic bottom
sediments, are especially vulnerable to oxygen
depletion. If the depletedwaters are circulated tothe
surface, the rate of oxygen uptake from the atmos-
phere is greatly enhanced and pockets of anaerobic
water are less likely to develop.
4.2.2 pH
The concentration of hydrogen ions in water is
measured in pH units. Waters of low pH (<7) are
acidic, those with pH = 7 are neutral,and those with
high pH (>7) are basic. The pH scale is inverse (in
terms of H* ions) and logarithmic; hence waterof pH
6 has 100 times as many H* ions as doesthat of pH
8. The pH of water is important biologically and
chemically. Below a pH of approximately 6 harmful
biological effects are felt, especially in sensitive life
stages such as eggs. Below a pH of about 4, only a
few specialized species can survive.
The biological effects of low pH are strongly
linked to other factors, particularly the nonhydrogen
ionic content of the water. Thus pH exerts a strong
effect on the form of many of the other contents in the
water. Ammonia, for instance, isfound intheform of
ionized ammonia (NH,*) and unionized ammonia
(NH,). The ionized form in which most ammonia is
found in acidic waters is several orders of magnitude
less toxic than the unionized form found in basic
water. This is the reverse of the general ruleof thumb
that the ionicforms of substances (which often form
in low pH waters) tend to be more toxic (Cairns et al.
1975).
Biologically, most of the direct effects of low pH
upon aquaticfauna appearto be related to problems
with disruption of osmoregulation (regulating blood
and tissue fluids) and control of the ionic balance of
blood and vascular fluids (Leivestad et al.
1976,1980, McWilliams and Potts 1978). The pH of
blood (as well as plant vascularfluids) exerts strong
effects onthe ionic speciation of itscomponents (i.e.,
the form in which the ion is found-.g., CO, may be
found in solution as CO,, carbonic acid, carbonate,
and/orbicarbonate, depending upon severalfactors,
the major one being pH). Since pH exerts strong
effects on metabolic chemistry, blood and vascular
pH must be maintained within relatively narrow
ranges. The blood of aquatic fauna is typically
separated from the surrounding water by a thin
semipermeable cell wall in their gills. Species or life
stages that have a high ratio of gill (or in the case of
eggs, chorion) surface area to body volume gener-
ally have the most difficulty compensating for ambi-
ent pH outside the nominal range for their blood
chemistry (Lee and Gerking 1980).
In the Florida Panhandle, surface waters of low
pH are generally found in swamps and swampdrain-
ages. Figure 43 gives the normal pH levels of
Panhandle surface waters. Rain water is generally
slightly acidic due to the presence of dissolved CO,
(forming carbonic acid) picked up from the atmos-
phere. Rainwater is, however, poorly buffered (i.e.,
possesses few ions that tend to stabilize pH levels).
Concerned that Panhandle rainwater may be be-
coming more acidic due to powerplant emissions,
the State and the Florida Electric Power Coordinat-
ing Group (an organization formed by the power-
plants within Florida) have undertaken broad-scope
acid rain studies. These studies are attempting to
determine whether the unique conditions found in
Florida increase or decrease the likelihood of acid
rain formation, whetherthese conditions increase or
decreasethe sensitivity of the ecosystem to acid rain
stress, and areas in or out of the State where the
effectsof Florida-caused acid rain may be felt (FDER
Panhandle Ecological Characterization
Figure 43. Minimum pH of Panhandle surface waters (after Kaufman 1975a).
1985b). If the rainwater contacts a substrate com-
posed of a buffering material (in the Panhandle this
is usually limestone-calcium carbonate, CaCO3),
then the pH moves toward what is known as the
equilibrium pH for that buffering reaction, that is,
toward the pH at which water in contact with that
particular bufferwill eventually stabilize. However, if
the water contacts only organic and insoluble sub-
strates (e.g., swamps and marshes), then it be-
comes quite acidic (pH 4 or below) from the organic
acids created by the decomposition of the vegeta-
tion, and the entire system stabilizes at a low pH.
These conditions yield community structures en-
tirely different from those found in water of higher pH,
since many species are excluded by their lack of
tolerance for the acidic conditions.
The pH of water bodies originating in these
organic wetlands often increases downstream be-
cause of the input of buffering ground water or
surface drainage (or both) or from contact with a
buffering streambed. Carbonate buffering in north
Florida ground water is sufficiently strong that the
addition of 5/%-10% of a moderately alkaline ground
water (pH approximately 8.0, alkalinity approxi-
mately 120 mg/I) has been shown to raise swamp
water with a pH of 4.0 and an alkalinity of 0 mg/I to a
pH of 6-6.5 and alkalinity of 6-12 mg/I (FDER
1985a). Since the pH scale is inverse logarithmic,
the 50/-10% ground-water addition, as a result of
chemical buffering reactions, reduced the concen-
tration of hydrogen ions by 99% or more. In the
Florida Panhandle, pH is almost entirely controlled
by the water's carbonate concentration (Kaufman
1975a).
Because of the substantial buffering effect of the
high ion content of saltwater, marine pH levels are
generally near 8. Thus problems from low pH are
rare in estuarine and marine waters.
58
87- 86o as, 840
ALABAMA
~~~~~2 -rn ZM 977rt:
GEORGIA
JIEFFE-rS
MINIMUM pH VALUES
[ 14.0-5.0
D 5.0-6.0
E 6.0 7.0
N GULF OF MEXICO
0 10 20 30 40 50
I 'Miles
4. Hydrology and Water Quality
4.2.3 Turbidity and Sediments
Turbidity is the result of particulate and colloidal
solids suspended in the water and is measured as
the proportion of light that is scattered or absorbed
rather than transmitted by a water sample. High
levels of turbidity are found in streams that carry
heavy sediment loads. This sediment is derived
from runoff and much of it, particularly that present
during periods of light to moderate rainfall, is com-
monly the result of human influences on the terrain
along the tributaries (e.g., land clearing, urban
stormwater drainage, farming without erosion con-
trol). In the absence of these anthropogenic influ-
ences, heavy rains may still temporarily increase
turbidity by washing larger particles into streams,
rivers, and lakes. These, however, tend to settle
rapidly.
High levels of turbidity may kill aquatic organ-
isms by clogging gill structures, causing suffocation.
Hard-bottom benthos can lose habitat if settling
sediment creates a mud bottom. Aquatic plants are
often affected by increases in turbidity by being
buried in deposited sediments or by reduced light
levels. Turbidity is a concern in drinking water
because it can harbor pathogens and protect them
from sterilizing efforts (e.g., chlorination). High tur-
bidity in drinking water sources, therefore, usually
necessitates that the particles be removed prior to
sterilization.
4.2.4 Dissolved Solids
The term "dissolved solids" refers to the total
amount of organic and inorganic materials in solu-
tion. The dissolved materials found in Florida sur-
face and ground waters are primarily the carbonate,
chloride, and sulfate salts of calcium, sodium, and
magnesium. Dissolved solids in both surface and
upper ground waters are usually below 200 mg/I
except for ground water along the coast (Shampine
1975a, Swihart et al. 1984) (Figure 44). Deeper
Figure 44. Concentrations of dissolved solids in Panhandle surface waters (after Dysart and Goolsby
1977).
59
840
1
87 86 85
ALABAMA
0 10 20 30 40 50
S I I I Miles
Panhandle Ecological Characterization
ground-water layers usually contain more dissolved
solids than the upper layers.
The major ions commonly found in Panhandle
waters are those often measured as alkalinity
(HCOf and SO,, bicarbonate and sulfate ions),
hardness (Ca" and Mg", calcium and magnesium
ions), and salinity. The total dissolved-solids con-
centration in surface water is generally highest dur-
ing low-flow conditions (Kaufman 1975b, Dysart and
Goolsby 1977).
Conductivity is a commonly used measurement
which is indicative of the concentration of dissolved
solids. Distilled water is a very poor electrical con-
ductor and ions in the water improve this conductiv-
ity. Dissolved solids concentrations can usually be
reliably estimated by multiplying the conductivity in
mhos by afactorrangingfrom 0.55to 0.75, depend-
ing on the water body (Dysart and Goolsby 1977).
a. Alkalinity. The concept of alkalinity is simple,
though the chemistry involved can be quite complex.
Alkalinity is a measure of the ability of water sample
to neutralize acid, in terms of the amount of H* (acid)
that can be added to the water before the pH is
lowered to some preset value (depending upon
which type of alkalinity measurement is being per-
formed). For the most common type of alkalinity
measurement (total alkalinity), this pH is 4.5. Ions in
the water that tend to keep the pH high increase
alkalinity and thus "buffer" the pH.
Buffering ions commonly found in Panhandle
surface and ground waters include carbonate (usu-
ally as bicarbonate) and sulfate. These components
are generally the result of the dissolution of the
limestone matrix with which the water has been in
contact. The ready solubility of limestone and the
frequent input of ground water (which has generally
had significant contact with limestone) to the surface
waterstendsto result in Panhandle surfacewatersof
at least moderate alkalinity.
As mentioned in the discussion of pH, alkalinity
in Panhandle water is very highly correlated to pH.
The various forms of carbonate found in the waters
are by far the predominant pH buffering agent; sul-
fate and other buffering ions are substantially less
common (Kaufman 1975a,b, Shampine 1975a).
Since the alkalinity of Panhandlewaters is over-
whelmingly a function of the carbonate concentra-
tions, many studies (particularly of ground water) do
not measure alkalinity as such, but rather record
bicarbonate concentrations. In surface waters total
alkalinity is more commonly measured because of
the increased likelihood that they may contain addi-
tional buffering ions caused by surface drainage and
input of human effluents. Alkalinity is not a water
quality factor of importance in marine waters be-
cause, though high, it is constant.
b. Hardness. The hardness of water, like the
alkalinity, is generally of concern in freshwater only.
Hardness is a measure of the cation (positive ion)
content of water. In the Panhandle the major fresh-
water cation is Ca", with Mg" a distant second.
Since calcium carbonate (limestone) supplies most
of the dissolved ions in surface and ground waters,
total dissolved solids, alkalinity, and hardness are
often highly correlated. The hardness of natural
Panhandlewaters can be reliably estimated fromthe
total dissolved-solids values (Figure 44). Hardness
is usually reported as equivalent concentrations of
calcium carbonate (e.g., 120 mg/I as CaCO,). High
levels of hardness (> approximately 2,000 mg/1) are
unpalatable but not generally harmful, except for a
laxative effect in first time users (Shampine 1975c).
One aspect of hardness that is of interest is its
relationship to soap and detergent usage. Soap
combines with and precipitates hardness ions until
they are removed. Only then do lathering and
cleansing occur. Harder water, therefore, requires
use of more soap than does soft water. Hard water
also increases the rate of lime formation within
plumbing and heating equipment and, where high,
may necessitate the use of chemical softening tech-
niques to minimize maintenance.
c. Salinity. Salinity is the concentration of
"salts" dissolved in water. This term is generally
used to describe estuarine and marine waters,
though very low concentrations of salts are present
in freshwaters. Sodium (Na') and chloride (C-) ions
provide about 86% of the measured salinity;
magnesium (Mg") and sulfate (SO4-) account for
another 11%, with the remaining 3% consisting of
various minor salts (Quinby-Hunt and Turekian
1983). Technically, the measurement of salinity has
been defined based upon the chlorinity, or chloride
4. Hydrology and Water Quality
(C-) content of seawater. This was done because of
the ease and accuracy with which Cl- concentrations
can be measured, and because the proportions of all
the different salts present in seawater are very con-
stant. The total concentrations of these salts are ap-
proximately 103to 104 times those found in freshwa-
ters. As a result, the chemistry of the freshwater
flowing into an estuary does not significantly affect
the proportions of the salts in the estuarine waters.
Salinity is a factor in water quality since salinity
tolerance can limit the species found in a given
salinity regime. Additionally, sudden or large
changes in salinity can be stressful or fatal to the
biota. The salinity tolerances of aquatic biota sepa-
rate them into three main groupings: freshwater
(salinities below 0.5 ppt), estuarine (0.5 to 30 ppt),
and marine (greater than 30 ppt) (Cowardin et al.
1979).
In general, the freshwater and marine species
have narrow salinity tolerances while estuarine
species are characterized by their tolerance to
changing environmental conditions, including salin-
ity. Estuaries, where fresh river waters mix with salt
water, regularly present rapidly changing salinity
conditions. As a result, this habitat has lower spec-
ies diversity than do more stable ones, although this
does not imply fewer individuals. Despite the harsh
physical regime, abundant dissolved nutrients pro-
mote high primary productivity that can support a
large number of individuals of tolerant species.
Separation of populations based on salinity toler-
ance applies equally to coastal wetlands.
The salinity of Panhandle coastal and estuarine
waters is extremely variable. These waters function
as a mixing zone for freshwater runoff from surface
and ground waters (0 ppt) and the offshore marine
waters (35 ppt). In general, estuarine salinities
range from 0 ppt throughout the estuary during high
river stages, to 32-35 ppt within the estuary (but
awayfromthe river mouth) during periods of low river
discharge. The coastal waters between the estuar-
ies often receive somefreshwater runoff during rainy
periods; however, the salinity regime is much more
stable than that of the estuaries, and diurnal salinity
changes are minimal or nonexistent.
d. Nutrients. The nutrient content of water pri-
marily affects water quality when high concentra-
tions promote excessive growth of algae and higher
plants. Too much eutrophication (i.e., nutrient
enrichment) causes excessive plant growth and the
resulting increased organic load depletes dissolved
oxygen, rendering the water less suitable for species
considereddesirabletopeople. The primary limiting
nutrients (i.e., those that, when lacking, commonly
limit algal and plant growth) are nitrogen (as ammo-
nia, nitrite, and nitrate), phosphate, and, for diatoms
(which often constitute the majority of fresh and salt
water phytoplankton), silica. There are many more
required nutrients; however, their availability is nor-
mally such that they do not prevent growth. In
addition to excessive plant and algal growth, high
concentrations of nitrates in drinking water also
cause a serious and occasionally fatal poisoning of
infants called methemoglobinemia (Slack and
Goolsby 1976, Phelps 1978a).
In a natural surface-water system, nitrogen as a
nutrient is derived from organic debris that is carried
by runoff from surrounding terrain and from aquatic
species of nitrogen-fixing plants and bacteria, and is
regenerated within the system through the decay of
dead plants and animals. These sources are often
augmented, sometimes heavily, by human effluent
discharges. The most common of these are sewage
treatment plants, septic tanks, and runoff from fertile
ized fields.
Phosphate and silica are derived, in an undis-
turbed system, from the weathering of continental
rock. They are both recycled repeatedly through the
cycle of death, decay, and subsequent uptake.
Florida has extensive areas of phosphorus rich lime-
stone matrix deposited during periods when the
State was covered by shallow seas. The dissolution
of this rock and its transport into both ground and
surface waters provide a ready source of this nutrient
in many Florida waters. The major anthropogenic
contributors include municipal sewage treatment
discharges (less of a problem since the mandatory
reduction of phosphate concentrations in deter-
gents), runoff from fertilized agricultural fields, and
effluent from phosphate mining operations. There is
little input of anthropogenic silica.
Panhandle Ecological Characterization
The limiting nutrients are not needed by algae
and plants in equal proportions. While the propor-
tions utilized vary widely between species and de-
pend upon environmental conditions, an average
ratio of N:P = 10:1 for higher plants and algae and
N:P:Si = 15:1:50 for diatoms can be used.
4.2.5 Temperature
Temperature affects water quality by acting as a
limiting factor if too high or too low for survival of a
specific organism, and by influencing the rate of
many biological and chemical processes including
metabolism. In general, higher temperatures in-
crease the rate of metabolic functions (including
growth) and the speed of other chemical reactions.
This tends to increase the toxicity and rate of meta-
bolic uptake of toxicants (Cairns et al. 1975). There-
fore, for those toxicants which are bioconcentrated
(accumulated within the tissues), higher tempera-
tures will result in higher concentrations in living
organisms.
Depending upon the size of the water body and
how well mixed it is, the water temperature may take
minutes or weeks to adjust to the average air tem-
perature. This lag time damps water temperature
fluctuations relative to air temperature fluctuations
and helps minimize the stress on aquatic lifeforms.
In additiontothe seasonalfluctuations,thereare
often diurnal fluctuations, particularly where turbid or
dark, tannic swamp waters are exposed to sunlight.
When the angle of incidence is small, water, as well
as many of its contents, absorbs solar energy very
efficiently. Dark coloration improves the efficiency
slightly, but restricts light penetration, and therefore
heating of the water, to nearthe surface. As a result,
surface water can become quite warm, while much
cooler water may exist below a shallowthermocline.
Freshwater surface temperatures vary depending
upon season and the volume, depth, and location of
the water body. Estuarine areas show the most
complex and rapid variations in watertemperatures.
The dynamics of freshwater inflow temperatures,
coastal marine water temperatures, density stratifi-
cation, tide, and wind determine the proportions of
fresh water and saltwater present at a site within an
estuary and may expose the inhabitants to very rapid
temperature fluctuations.
Locally, surface-water temperatures may be
strongly influenced by ground-water input. Ground-
water temperatures tend to remain very near the
mean annual temperature of the above-ground cli-
mate. This is another example of temperature
damping on a larger scale, the result of the slow rate
at which the earth changes temperature. Where
ground waterflows into surface waters, the tempera-
ture of the water near the ground-water input will be
relatively stable.
Temperature becomes a water quality problem
when it is too cold or warm to support a normal
ecosystem. Low-temperature kills are almost exclu-
sively a natural product of winter cold spells and are
of short duration and temporary effect. High tem-
peratures, however, can become a long-term prob-
lem when large quantities of water used to cool
power plants and other industrial operations are
discharged into surface waters. It is not uncommon
for thermal effects to be felt over a large area where
substantial quantities of heated water are dis-
charged.
4.2.6 Other Contents
This catchall grouping includes many para-
meters of great concern. Among these are: toxic
substances such as ammonia, pesticides, and met-
als (e.g., lead, mercury); carcinogens (cancer-caus-
ing agents), mutagens (DNA-altering agents), and
teratogens (agents causing abnormal growth or
structure); and infectious agents (bacteria and vi-
ruses). Many substances fit within two or more of
these categories.
Metals and many of the toxic compounds in
waterareoften found in ionic forms. Most pesticides
and toxic organic compounds, however, do not re-
quire ionization to be toxic. Many toxicants, ionic or
not, interfere with normal metabolic processes by
displacing critical metabolites and thereby blocking
reactions necessary for the maintenance of life.
While many ions are not toxic (at least at the
concentrations at which they are normally found),
the ionic forms of many elements and compounds
are generally more reactive than are the nonionic
forms. Additionally, different ions of the same sub-
stance may vary in their toxicity. Generally, the
higher the valence number (i.e., the number of
4. Hydrology and Water Quality
charges on the ion), the more toxic the ion. As a rule,
low pH increases ionization and, therefore, the tox-
icity of many substances.
The total concentration of the subject com-
pound, along with otherfactors such as pH, tempera-
ture, ionic strength (i.e., the concentration of all ionic
forms present), and the presence of natural (and
anthropogenic) chelating agents such as tannins
and lignins, combine to determine the concentra-
tions at which the various ionic and nonionic forms of
a compound will be found. Since the toxicity (if any)
of that compound is affected by its exact form and
availability for uptake, and since the mode of that
uptake varies widely between species, predicting
the toxicity of effluents being discharged to surface
and ground waters is very difficult. The conditions
found in the area of each discharge play an important
role in determining the effect of an effluent on area
ecology. This is further complicated by the long
period after exposure which may elapse before the
onset of symptoms, especially common in the car-
cinogens, teratogens, and mutagens. Since these
conditions typically fluctuate, sometimes widely,
during the year, it can be seen that predicting pollut-
ant impacts can be very difficult.
4.3 Major Influences on Surface Water
4.3.1. Major Influences on Surface-Water
Hydrology
a. Natural factors affecting Inland surface-
water hydrology. In drainage basins not subjected
to major human alterations, such factors as climate,
season, geology, and surface features control the
hydrology. In the Florida Panhandle, climate and
season combine to control precipitation, evapora-
tion, and evapotranspiration rates, thereby deter-
mining the proportion of water contained in each step
of the hydrologic cycle. The geology and topography
control flow rates by determining surface porosity,
slope, and erosion features. These flow rates are
further modified by the presence and types of vege-
tation that impede runoff.
Flooding is one of the most striking hydrologic
events. Panhandle rivers flood primarily during the
frontal rainfalls of late winter and early spring (Feb-
ruary-May) (Palmer 1984) (Figure 45). While this
I tpainuiilcua inver i
15 . .... . .. .... ...... ... .... ..........
S15
C o5 ... ...........................
2
0. .
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Figure 45. Seasonal riverflow in two Florida
Panhandle rivers (data from Livingston 1983,
Palmer 1984).
difference is partially due to the winter rainy period,
Figure 17 in the climate chapter shows that the total
rainfall during the summer is much greater. The vast
quantities of water evaporating from the warm sur-
face waters and transpired from the lush foliage
return most of summer rainfall to the atmosphere
(Mather et al. 1973), thereby minimizing flood-induc-
ing runoff. While the large Panhandle rivers show
this relationship (Figure 46), they also show reduced
flow during the summer rainy season because much
of their drainage basins are sufficiently far inland that
they receive little of the convection-induced summer
rains. The reduced foliage present in winter and
early spring allows a greater proportion of the rain
falling during the winter rainy season of the northern
regions to run off and may result in flooding.
30.
a River Flow
Rainfall
20
S210.
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Figure 46. Apalachicola River flow and rainfall at
city of Apalachicola (data from Livingston 1983).
Panhandle Ecological Characterization
Periodic floods are a necessary and important
part of wetland energetic. Seasonal inundation of
river flood plains and coastal marshes flushes or-
ganic matter produced by these wetlands into
streams, rivers, and estuaries where it provides a
substantial portion of the energy driving the food
chain. The goal of minimizing property damage from
flooding while maintaining high water quality in sur-
face waters is best achieved by discouraging devel-
opment in riverflood plains and controlling construc-
tion of what development does take place to mini-
mize damage to the resulting structures and to the
flood plain (e.g., requiring that buildings be con-
structed on pilings above flood levels and that flood
plain terrain and vegetation be maintained).
Maps delineating the 100-year flood plains in
Florida were drawn by the U.S. Geological Survey
and are currently distributed by the Florida Resour-
ces and Environmental Analysis Center (FREAC) at
Florida State University. These maps are based
K
upon the USGS topographic quadrant maps and
have too much detail to present here. It is probable
that, because of changes from continuing develop-
ment and other factors, these maps underestimate
the areas that would be inundated by 100-year
floods.
Panhandle springs moderate the flow of those
rivers and streams receiving their waters. The
ground-water levels controlling the rates of spring
flow and ground-water seepage tend to respond
slowly to rainfall changes, thereby establishing a
minimum streamflow ("base flow") when surface
runoff is minimal. This moderating tendency is less
noticeable during periods of high runoff and stream-
flow. However, many springs become siphons
under these conditions and carry surface water
directly to the aquifers (Ceryak et al. 1983), thereby
reducing the peak streamflow somewhat. First and
second magnitude springs (>30 m3/s and 3-30 m3/s,
respectively) (Figure 47) are most numerous in the
87 86 85 84o
I T I I
S ALABAMA
SANTA ROSA HOLES
'- I /. o /
A L0
S'0: Yl A GEORGIA
A / I I J } WASHINGTON F
'^^W F -
BA L LEON
Less than 10 ft3/sec\ '- ERTY
o 10-100 ft3/sec L
A Greater than 100 ft3/sec
.SGULF A
GULF OF MEXICO
0 10 20 30 40 50
S I I Miles
I
Figure 47. Locations and magnitudes of major Panhandle springs (after Rosenau and Faulkner 1975).
64
4. Hydrology and Water Quality
central Panhandle and are located primarily along
the Choctawhatchee and upper Chipola Rivers and
Econfina Creek. Third magnitude springs (<3 m3/s)
are less concentrated but are generally more com-
mon east of Walton County.
b. Natural factors affecting coastal surface-
water hydrology. Coastal waters are affected by
several forces that have little affect on the freshwa-
ters inland. In shallow nearshore areas such as
those common along the eastern Panhandle coast
and in estuaries, wind is the major factor driving
water circulation (Williams et al. 1977, Livingston
1983). This results in a net long-term movement of
water west along the coast during the late spring,
summer, and early fall and east along the coast
during the winter months. Short-term currents are
quite variable and depend primarily upon: (1) local
wind direction, (2) tide-induced currents, (3) proxim-
iyto river mouths and the estuarine currents result-
ing from the density differences of the mixing fresh
and salt water, and (4) the possible presence of
eddies spun off of the Loop Current in the Gul of
Mexico.
(1) During much of the year, local wind direction
is affected by the convective phenomenon driving
the land breeze and sea breeze. Wind strength and
direction and the resulting force exerted on the
surface waters often changes over short periods of
time. Chapter 3 contains more information on sea-
sonal changes in wind strength and direction.
(2) The Panhandle coast experiences unequal
semidiurnal tides; i.e., two high and two low tides
daily, each of different magnitude. This pattern is the
result of a complex combination of forces, the grav-
itational pull of the Moon and the Sun being the
primary ones. The period of the tides is such that
they are approximately one hour later each day. The
net tide-induced current is weakly west along the
coast (Battisti and Clark 1982). Of more importance
to the nearshore hydrology and water quality, the
(normally) four times daily change of direction of this
movement ofwater induces substantial mixing of the
nearshore and offshore waters.
(3) A number of current-producing and -affect-
ing forces are in action at the mouths of rivers.
Among them are (a) the friction of the riverflow upon
the salt water it enters, (b) salt-wedge circulation,
and (c) geostrophic forces. The friction of the flow
exiting the river mouth attempts to "drag" adjacent
saltwater along withthe body of riverwater, inducing
eddies along the transition zone between the two
water masses. A salt wedge forms because fresh
water flowing out of the rivers is less dense than the
salt water into which it flows; thus the fresh water
tends to form a layer flowing over the top of the
densersaltwater(Figure 48a). This underlyinglayer
of salt water is called a salt wedge, and since the
upstream end of this wedge has a lower salinity (is
less dense) from mixing with the overlying river
water, pressure from the denser salt water behind it
forces the wedge upstream. In shallow, so-called
well-mixed estuaries (the type found along the
Panhandle coast), turbulence and other mixing
forces tend to minimize the distance over which
these two water masses remain unmixed. However,
the mechanism is still functioning and an important
part of estuarine hydrology. As the saltwater mixes
with the overlying fresh water at their interface, the
brackish water formed is less dense than the salt
water and is caught up in the outward flow of fresh
water and carried out toward the gulf. This loss of
saltwater from the wedge induces a flow of saltwater
from the gulf to replace it. Thus the estuary experi-
ences a net outflow in the surface waters, and a net
inflow in the bottom waters. This inflow can be
several times the volume of the riverflow before it
enters the estuary (Knauss 1978). What are per-
ceived as small changes in river flow can result in
large changes in estuarine and nearshore circula-
tion.
Others factors in estuarine circulation are those
caused by Coriolis and geostrophic forces. The
Coriolis 'force" in the northern hemisphere is felt as
a force directed to the right of the direction of water
flow. The result of this force, when applied to an
estuary exhibiting stratified salinity, is that inflowing
fresh surface water tends to collect on the right side
(relative tothe direction of flow) of the estuary (Figure
48b). In the Panhandle, the resulting thicker layer of
fresh water is then forced west along the coast by
geostrophic forces caused by the pressure from the
denser, more saline waters to the south or east.
These two forces, in the absence of strong coastal
currents, cause the outflow of rivers in the Pan-
handle to tend to curve to the right once they reach
Panhandle Ecological Characterization
Figure 48. (A) Formation of a salt wedge and "stacking" of freshwater layer to right of flow direction
at river mouths. (B) Coriolls and geostrophlc forces affecting fresh water flowing from river mouths.
66
4. Hydrology and Water Quality
the ocean (Knauss 1978). Once free of the river
banks, these forces will tend to keep the surface
layer of freshwater "pinned" to the coast and force it
west along the coast until mixing destroys the strati-
fication. The magnitude of the effect of these forces
on coastal and estuarine circulation depends
strongly on the presence or absence of mixing forces
at the time, thus they are continually in a state of flux.
A final influence on coastal hydrology is wave
mixing and erosion. Wave motion does not result in
significant lateral movement of water; however,
vertical mixing takes place to a depth approximately
twice the wave height. In shallow areas such as the
eastern Panhandle nearshore region, large storm-
induced waves caused the waters to be well mixed
top to bottom. During periods of wave heights
greater than approximately 1 m, therefore, the east-
ern Panhandle coastal waters would be expected to
exhibit very little temperature or salinity stratification.
c. Anthropogenic factors affecting Inland
surface-water hydrology. Development often
substantially alters surface drainage. In the Pan-
handle these alterations include river damming,
streamflow diversion, river channelization, dredge-
and-fill activities, "terraforming," increasing runoff
(e.g., stormwaterdrainage), wetland draining, flood-
plain development, and extensive landclearing
activities. The most common results of these altera-
tions are increased magnitude and duration of flood-
ing and the decreased water quality of runoff.
Undeveloped uplands in drainage basins act as a
buffer to runoff, absorbing the initial rainfall and
impeding the rate at which excess water runs off.
Developed lands generally have a much reduced
ability to absorb rainfall due to the reduced amount
of absorptive "litter," reduced permeability of the land
surface, and reduced evapotranspiration due to
lower foliage densities. In addition, most develop-
ment includes measures such as regrading of the
terrain and installation of drainage ditches and cul-
verts, all aimed at speeding the rate of runoff. As a
result, the streamflow in developed basins following
periods of rainfall tend to peak rapidly and at a much
higher level than it does in undeveloped basins. This
is caused by a greater total volume of water draining
into the stream or river over a shorter total period of
time. This problem is further exacerbated by the
tendency of developed drainage basins to restrict
the area through which the stream or river flows
during high water conditions. This area, the
floodplain, is the width of river channel required to
carry the runoff during periods of heavy rainfall in the
basin. After this floodplain is developed, which
commonly includes reducing its width bydumpingfill
along its borders, the increased runoff resulting from
the development must now flow through a more
restricted channel. As a result the height of flooding
is increased even more. The increased rate of runoff
in developed basins also increases erosion, which
further reduces landcover and retention of rainwater.
d. Anthropogenic factors affecting coastal
surface-water hydrology. Human alteration of
freshwater input can also alter coastal estuarine
systems. Diversion of surface waters to different
drainage basins and alteration of the dynamics of the
hydrologic cycle by anthropogenic activities (e.g.,
consumptive water use) can cause profound
changes in patterns of freshwater flow to estuaries
and coastal marshes, with potentially devastating
results. It has been previously described how river
outflow induces circulation and mixing in water
masses many times greaterthanthe volume of water
discharged. Thus the size of an estuary is controlled
by the volume of fresh water inflow, but any decrease
of inflow causes a much larger decrease in the
volume ofthe estuary. I average flow into an estuary
decreases, then decreases in estuarine productivity
disproportionate to the volume of fresh water di-
verted can be expected.
4.3.2 Major Influences on Surface-water
Quality
a. Natural factors affecting Inland surface-
water quality. The major natural influence govern-
ing surface water quality is the progression of the
seasons. Surface waters are commonly composed
of some mixture of excess rainwater drained from
surrounding lands, flow from the Surficial Aquifer,
and artesian flow from the Floridan Aquifer. Sea-
sonal factors which affect surface water quality in-
clude rainfall, airtemperature, and nutrient sources
"Normal" rainwater is slightly acidic with a very
low concentration of dissolved minerals (i e., soft
water). The water is poorly buffered and the pH is
easily changed by the materials it contacts. During
the rainy seasons, surface streams, rivers, and lakes
Panhandle Ecological Characterization
are composed primarily of rainfall runoff, with ground
water constituting a relatively small proportion. The
rainwater picks up tannic and other organic acids
through contact with organic debris during runoff,
particularly that encountered during the relatively
long periods of retention provided by swamps and
marshes. This swamp runoff is acidic (pH 4-5) and
highly colored, with a relatively low DO and a very
low concentration of dissolved minerals.
During periods of low rainfall, ground water
makes up an increased proportion of most surface
waters. Since ground waters are frequently highly
filtered and have spent time in contact with the
minerals composing the aquifer matrix (primarily
limestone), they are generally colorless, moderate-
ly alkaline, and contain moderate to high levels of
dissolved minerals. Since surface runoff often has
weak organic acids acting as buffers, the pH of
surface water mixed with a small amount of ground
water can change radically. As a result of these
factors, surface water chemistry (especially pH)
tends to reflect seasonal rainfall patterns.
In addition to the direct correlation between air
temperature and water temperature, airtemperature
has many indirect influences on surface water. As
discussed previously, ambient temperatures affect
chemical reaction rates and equilibria reactions in
water. As a result, rates of bioconcentration of toxics
are higher in warmer water, as are rates of nutrient
production and utilization. Anotherfactor influenced
by air temperature is plant growth.
Seasonal change in ambient temperature is one
of the primary factors controlling plant and often
animal growth and reproduction, both in the drainage
basin and within water bodies. The growth and death
of biota are major factors in nutrient cycling and in the
levels of dissolved nutrients found in surface waters.
Nutrient levels tend to decrease during periods of
maximal population growth and increase during
periods when deaths (and therefore nutrient regen-
eration) exceed reproduction and growth.
Surface runoff leaches nutrients from upland
litter, which are then carried to downstream water
bodies. Additionally, some of the litter is carried into
the water, where it settles to the bottom and decays,
providing shelter and food for detrital feeders as well
as nutrients for primary production.
b. Natural factors affecting coastal surface-
water quality. The water quality of nearshore wa-
ters is subject to many of the same climate induced
changes that affect inland waters; however, by virtue
of theirvolume,the coastal waters are more resistant
to change. Nearshore water quality is primarily
determined by the mixing dynamics resulting from
the previously discussed hydrologic factors. These
factors control the mixing of the fresh water draining
off the land and the marine waters offshore. One
relatively common event which is harmful to the
ecology occurs when conditions encourage plank-
ton blooms. The exact causes triggering these
blooms are not fully understood; however, the dense
blooms Introduce metabolic byproducts that are
toxic to many species and can produce fish kills. The
BOD from these kills, along with the enormous
respiratory oxygen demand of the plankton at night
and during overcast periods, can result in low levels
of dissolved oxygen, increasing the kill. These
problems are worst in constricted waters near shore.
c. Anthropogenic factors affecting Inland
surface-water quality. Until recently, point-source
pollutant discharges have beenthe major human-in-
duced cause of water quality changes. In the Pan-
handle, much of which is relatively undeveloped,
private and municipal sewage and discharges are
the most common point-source effluents. Industrial
activity is generally found in the western portions of
the area. These sources, fewer in number but which
may have substantial local impact, include dis-
charges from powerplants, chemical factories, pa-
per mills, and mining operations. Discharges from
powerplants are primarily in the form of thermal
effluents, i.e., water that has been used to cool the
generators.
Nonpoint-source pollution is considered by the
FDER to be a major, but largely uncontrolled, cause
of surface water degradation. It is estimated from
studies that nonpoint sources contribute 450 times
more suspended solids, 9 times more oxygen-de-
pleting materials, and 3.5 times more nitrogen than
point sources (FDER 1986c). The major nonpoint-
source pollutants in Panhandle rivers are pesticides,
animal wastes, nutrients, and sediments. The major
4. Hydrology and Water Quality
causes of nonpoint-source pollution in southeastern
U.S. river basins are agriculture (affecting 62% of
basins) and urban stormwater runoff (affecting 57%
of basins), with silviculture (tree farming), landfills,
and septic tanks affecting 33% of the basins (U.S.
EPA 1977). Nonpoint-source pollution is expanding
and has the potential to nullify water-quality gains
being made through the reduction of point-source
emissions.
d. Anthropogenic factors affecting coastal
surface-water quality. The primary impact of
human activities on coastal water quality results from
the restriction of water circulation in dredged or oth-
erwise altered areas. This may result in high tem-
peratures, low DO, and salinity alterations. One of
the greatest effects of human activities results from
salinity alterations caused by the changes in hydrol-
ogy previously described in 4.3.1(d). The factors
affecting inland surface-water quality may affect
local coastal water quality, particularly in the estuar-
ies.
4.4 Major Influences on Ground Water
4.4.1 Major Influences on Ground-water
Hydrology
a. Natural factors affecting ground-water hy-
drology. In the absence of cultural impacts, ground-
water levels are a function of rainfall. Ground-water
levels respondto area-wide rainfall with a lagtime of
up to several weeks (Ceryak 1981). Since substan-
tial lateral transport is possible, levels tend to follow
fluctuations in rainfall averaged over substantial
areas (up to thousands of square kilometers).
Ground water movement is from areas of high to
those of low potentiometric surface (Figure 39).
Recharge of the Floridan Aquifer from rains and
infiltration of surface water depends on the permea-
bility andthickness ofthe overlying strata and, where
there is a surficial aquifer, depends upon the differ-
ence in head pressure betweenthis overlying aquifer
and the Floridan Aquifer aswell as on the permeabil-
ity of the confining layer separating them. During
periods when the Floridan Aquifer's potentiometric
surface is locally low, rains may cause the Surficial
Aquifers pressure to be greater than that of the
Floridan, with subsequent downward percolation to
the Floridan. At other times, however, the poten-
tiometric surface of the Floridan may be greaterthan
that of the Surficial Aquifer and no recharge to the
Floridan takes place. In this situation, waterfromthe
Floridan Aquifer may seep upward into the Surficial
Aquifer. In instances where the Floridan Aquifer is
confined and its potentiometric surface is above the
land surface or above the level of overlying surface
water, springs and seeps may flow from the aquifer
and find their way into surface waters. High surace
water levels (i.e., floods) and/or low ground-water
levels may convert the springs into siphons, thereby
draining surface waters directly into the aquifer
(Ceryak et al. 1983) (Figure 49). This is common for
the springs along many rivers and, in the instances
of springs flowing through large underground pas-
sages, may allow substantial volumes of surface
water to mix with ground waters, increasing the
opportunity for large-scale contamination of ground
waters with surface pollutants.
b. Anthropogenic factors affecting ground-
water hydrology. Ground-water levels are affect-
ed, often extensively, by human activities. Four
major impacts presently exist in the Panhandle:
(1) ground water withdrawal; (2) drainage wells;
(3) pressure injection wells; and (4) surface hydrol-
ogy alterations.
(1) Groundwater withdrawal tends to lower the
potentiometric surface in the immediate vicinity of a
well. As a result, ground water tends to flow lateral-
ly toward the pumped well to fill the potentiometric
"hole," or cone of depression. The rate of this flow
depends upon the local permeability of the aquifer
and the pressure gradient between the well and the
surrounding aquifer. Another factor affected by
ground-water pumping is the depth to the saline
layer underlying the fresh-water aquifers. Especially
near the coast, excessive pumping of ground water
results in saline intrusion into the potable aquifer.
Because the density difference between the fresh-
water aquifers and the deeper saline ground waters
is minimal, the permanent lowering by 1 ft of the
upper surface of the Floridan fresh water indicates
that approximately 40 ft of of the fresh water was
removed and that the upper surface of the underlying
saline aquifer rose nearly 40 ft.
Panhandle Ecological Characterization
F Groundwater Confining Layer r i
Figure49. Generalized relationship of surface waterto ground waterfor springs and siphons.
4. Hydrology and Water Quality
(2) Drainage wells have been used extensively
in some areas to drain perennially-wet orflood-prone
areas. These wells are drilled into an aquifer and the
boreholes left open. "Excess" surface drainage is
then directed to the holes. It is also common, in
suitable areas, that sink holes connecting to ground
water are used in place of drilled wells. The use of
drainage wells has decreased markedly because of
concerns about the poor quality of water draining into
the aquifers. Attempts by the water management
districts to locate these wells to help in water man-
agement planning have been hindered by the age of
many of them and by poor records of their existence.
At the time of this writing the USGS is preparing a
map of known drainage wells (Kimrey, in prep). It is
unlikely that most of the drainage wells in the Pan-
handle and in the State will be located.
(3) Pressure injection wells are used in various
locations throughout the State as a means of waste-
water and storm-water disposal. These techniques,
when used with storm water and with appropriate
caution towards their potential for ground-water
contamination, may help recharge the aquifer with
water that would otherwise evaporate or run off.
Pressure injection wells are of two primary types,
those injecting into the fresh-water aquifers and
those injecting into the saline-water aquifers. Injec-
tion into many potable water zones yields little in-
crease in storage since the artesian aquifers are
already full, so this type of injection well is little used.
Liquid wastes are being injected into saline
waters in the deeper zones of the Floridan Aquifer as
a storage and disposal method. There is evidence
that this use is expanding, especially in storing or
disposing of secondarily treated sewage effluent
(Hickey 1984). The USGS has mapped the general
locations of deep saline aquifers that might be suit-
able for liquid waste disposal (Miller 1979). Waste
water is also injected into nonpotable areas of saline
intrusion to create a back pressure and slow further
intrusion (Stewart 1980). Because of concern over
the long-term effects of this practice, the USGS is
involved in extensive investigations into this practice
(e.g., Kaufman 1973; Pascale 1976; Pascale and
Martin 1978; Ehrlich et al. 1979; Hull and Martin
1982; Vecchioli et al., in press; Merritt, in press) and
chemical changes in the wastes following injection.
Temporary storage of freshwater (storm water) in
saline aquifers is being evaluated by the USGS in
south Florida.
(4) The surface hydrology of aquifer recharge
areas serves to channel water to or away from
recharge areas (Figure 40). Recharge through sink-
holes and other breaches of the confining layer, and
by percolation through porous soils can be easily
altered by human activities. Wetlands may serve to
hold water over areas of low porosity, thereby in-
creasing the amount of water percolating to the
aquifer. Diversion of surface drainage to, or away
from, sinkholes and wetlands, as well as speeding
surface drainage away from recharge areas as a
flood prevention measure, affects the amount and
quality of water recharging the aquifer. Develop-
ment activities, especially in recharge areas, must
be performed carefully to ensure protection of
ground-water supplies.
4.4.2 Major Influences on Ground-water
Quality
a. Natural factors affecting ground-water
quality. Many areas in the Panhandle function as
recharge areas for the Floridan Aquifer (Figure 40),
and the Floridan Aquifer, being unconfined in much
of the Panhandle, is recharged throughout most of
the area where it exists. There is often a general
perception that surface water contacts ground water
only after it has very slowly percolated through puri-
fying layers of soil and rock. In Florida, including the
Panhandle, this perception is generally incorrect. In
many ground-water recharge areas, the surface
bodies of water and surface runoff are directly
connected to the ground water by channels through
the intervening rock. Below the surface of the land,
Florida is largely a sponge of karstic limestone
penetrated by innumerable solution channels and
sand beds. Though these porous layers of limestone
are often separated by confining layers of clay and
rock, their connections to the surface and to surface
waters is evident in the numerous springs and sink-
holes which dot Florida's landscape. Many sink-
holes act as drainage gutters, providing direct
contact between contaminated or uncontaminated
surface runoff and the ground-water aquifers. The
Sand and Gravel aquifer is just a layer of fine-to-
coarse quartz sand sometimes mixed with small
quartz or chert gravel (Hyde 1975) lying on top of a
confining layerand exposed at the ground's surface.
Panhandle Ecological Characterization
Percolation of surface waters into this aquifer is fast
and relatively unobstructed.
Ground waterfrom the Floridan Aquifer is char-
acterized by high pH, alkalinity, and hardness. This
results from contact with the limestone within which
the Floridan is found. Water from the Sand and
Gravel Aquifer is acidic and has low concentrations
of dissolved solids. The normal ground water char-
acteristics in the shallower aquifers are affected by
surface water hydrology. During periods of high
surface water, substantial quantities of often dark,
acidic swamp runoff find their way into and mix with
(or replace) the ground water, rendering the quality
of water from shallow wells similar to that of the
surface waters.
b. Anthropogenic factors affecting ground-
water quality. Anthropogenic effects on ground-
water quality takes three forms: (1) contamination
via surface waters and leaching of surface contami-
nants; (2) contamination via direct means, i.e.,
drainage wells and injection wells; and (3) increas-
ing intrusion of saline waters into potable aquifers
through excessive pumping of ground waters.
(1) The Surficial Aquifer, the Sand and Gravel
Aquifer, and the Floridan where it is unconfined (not
covered by a stratum of low permeability) are often
at or near the surface and are by their proximity
easily contaminated. Even where beds of low per-
meability overlie the aquifer (Figure 50), surface
contaminants are relatively easily introduced. The
terms "confining beds" and "low permeability" were
drafted by hydrologists describing the movement of
ground water. For purposes of water consumption,
an overlying or surrounding stratum of low permea-
bility may slow local ground-water recharge suffi-
ciently to prevent large withdrawals of water from an
area. Percolation rates measured in inches per day
are very slow in terms of aquifer recharge, but all too
fast in terms of movement of contaminants toward
potable aqufers.
(2) Drainage wells have been in use for some
time, sometimes for the disposal of sewage and
other effluents, usually for the disposal of unwanted
surface water. Concerns have been raised overthe
possible health effects of such activities, and their
use is being actively discouraged. Injection wells are
relatively new and, as is discussed in 4.4.1(b), their
effects are being studied intensively by the USGS
and they are heavily regulated by the U.S. Environ-
mental Protection Agency (EPA) and the FDER.
(3) Salt water intrusion is becoming an increas-
ing problem, especially in coastal areas. Withdraw-
al of excessive volumes of ground water increases
intrusion of saline waters, as discussed in 4.4.1(b).
One aspect of this that is often overlooked is that
intrusion of saline waters into the shallow ground
waters along the coasts (where the potable aquifers
are thinnest) can change the makeup of overlying
vegetation by killing species that are not salt tolerant.
4.5 Area-wide Surface-water
Hydrology and Water Quality
The seven major Panhandle coastal rivers origi-
nate in Georgia or Alabama. Changing land use in
these States, as well as in the Panhandle, is directly
affecting the rivers' hydrology and water quality
(FDER 1986c). There has been some successful
cooperation among the States in investigating the in-
terstate drainage basins (e.g., U.S. Dept. of Agricul
ture 1977), but less in instituting interstate correc-
tions to problems.
Table 3 gives major drainage basin and water-
body sizes as well as streamflows for Panhandle
lakes and rivers. Foose (1980) givesdrainage basin,
river, and lake areas for Florida including the Pan-
handle. His laterwork (Foose 1983) includes further
statistics concerning flow characteristics of Florida
rivers. The Northwest Florida Water Management
District (NWFWMD) has published reports on the
flood damage potential of the district (NWFWMD
1977); on the availability of water for industrial uses
within the district (NWFWMD 1980a); on the availa-
bility of water resources in the peninsula area of
southem Santa Rosa County (NWFWMD 1979b)
and southern Okaloosa and Walton Counties (Barr
et al. 1981); summarizing available rainfall data for
the Panhandle (Kennedy 1982); and an exhaustive
statistical summary and inventory of Panhandle
lakes and streams which should answer most ques-
tions concerning hydrologic regimes and the fre-
quency with which a given hydrologic condition
occurs (Maristany et al. 1984).
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Panhandle Ecological Characterization
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Panhandle Ecological Characterization
temperatures near 10 oC in winter and maximum
temperatures near 30 C in summer. Shallow shel-
tered embayments and other areas with minimal
mixing with offshore waters may, however, have
greater temperature ranges than these.
The FDER ranked Florida lakes, based primari-
ly upon their trophic state, in an effort to objectively
determine those most in need of restoration and
those most in need of preservation (Myers and
Edmiston 1983). This ranking was based largely
upon a report by the University of Florida, Depart-
ment of Environmental Engineering Sciences
(1983). Results pertaining to the Panhandle drain-
age basins are included in the following sections;
however, since this ranking was performed on lakes
where prior studies provided sufficient data, and
since public interest was a factorweighed in assign-
ing rank, it is not a definitive statement of the relative
conditions of all lakes in Florida.
4.6 Area-wide Ground-water
Hydrology and Water Quality
Ground water within the Florida Panhandle is
influenced by the hydrology and water quality of the
overlying surface water; however, the flow of ground
water is little affected by the flow constraints of the
overlying drainage basins. As a result the discussion
of some aspect of ground water often includes fac-
tors from more than one drainage basin. Although
ground water is discussed in the following drainage
basin sections, each discussion is largely restricted
to the effects of the surface waters in that particular
basin upon the ground water. Studies looking at the
aquifers on a larger scale and across more than one
drainage basin are covered in this section.
The Floridan Aquifer contains most of the non-
saline ground water in the eastern portion of the
Panhandle and is the primary potable water source
in this area. Beginning in Okaloosa County and
continuing westward, the Floridan is located deeper
and its water becomes highly mineralized; therefore
the Sand and Gravel Aquifer is more commonly used
in these areas (Figure 37). The approximate thick-
ness of the potable-water zone in the Floridan is
shown in a USGS map (Causey and Leve 1976).
Parts of Bay County use Deer Point Lake as a water
source since the Floridan in that area has relatively
low transmissibility and does not support large well
fields (U.S. Army Corps of Engineers 1980a).
The Surficial Aquierconsists of a porous, sandy
surface layer recharged locally and is separated
from the underlying Floridan Aquifer by a clay-con-
taining layerof low permeability-a confining layeror
aquitard. The Surficial Aquifer varies in thickness
and, where the underlying Floridan or the confining
layer are at the surface, may not exist at all. To the
west the Surticial Aquiferthickens and deepens and
becomes the Sand and Gravel Aquifer (Figure 38).
Additional small but usable quantities of water exist
in some areas within the clay and sandy-clay confin-
ing layer separating the aquifers; however, except in
rural areas with small requirements, these are little
used because of the larger volumes available in the
major aquifer. Because of the occurrence of this
ground water within the confining layer, iis some-
times called the Intermediate Aquifer. Its primary
action, however, isto restrict the movement between
the Surficial or Sand and Gravel Aquifers and the
underlying Floridan Aquifer.
The average temperature of the top 25 m of
ground water in the Panhandle range is approxi-
mately 21 C, varying about 4 C throughout the year
(Heath 1983). The shallow aquifers vary more than
the deeper ones.
The USGS has conducted numerous investiga-
tions of the water resources of the Panhandle (Table
4). These include an examination of ground-water
levels and water quality along the coast from Walton
to Escambia Counties (Barraclough and Marsh
1962) and a later more detailed look at the water
resources of Walton County (Pascale 1974). Both
the Sand and Gravel Aquifer and the Floridan Aqui-
fer are important in this county, with the Sand and
Gravel storing water for stream baseflow and re-
charging the underlying Floridan. The Sand and
Gravel is also used as a rural water supply. The
Floridan is the primary water supply in the county.
Transmissivity within the aquifer is highly variable.
The Floridan is exposed in Alabama north of the
Walton County where it is recharged by rainfall.
Ground water within the Floridan moves south, dis-
charging by springs and seeps along the Choctaw-
hatchee River and by leakage to Choctawhatchee
Bay and the gulf.
4. Hydrology and Water Quality
Table 4. U.S. Geological Survey Maps for the Florida Panhandle
Surface-water Hydrology
1. Runoff from hydrologic units in Florida (Hughes
undated).
2. Runoff in Florida (Kenner 1966).
3. Annual and seasonal rainfall in Florida (Hughes
et al. 1971).
4. Surface water features of Florida (Snell and
Kenner 1974).
5. Water-level fluctuations of lakes in Florida
(Hughes 1974).
6. Low streamflow in Florida-magnitude and fre-
quency (Stone 1974).
7. Seasonal variation in streamflow in Florida
(Kenner 1975).
8. The difference between rainfall and potential
evaporation in Florida (Visher and Hughes
1975).
9. Average flow of major streams in Florida (Ken-
ner et al 1975).
10. An index to springs of Florida (Rosenau and
Faulkner 1975).
11. River basin and hydrologic unit map of Florida
(Conover and Leach 1975).
12. Florida: Satellite image mosaic (U.S. Geological
Survey 1978).
13. Long-term streamflow stations in Florida, 1980
(Foose and Sohm 1983).
14. Hurricane Frederic tidal floods of September
12-13,1979 along the Gulf coast, Oriole Beach,
Garcon Point, Holley, south of Holley, and
Navarre quadrangles, Florida (Franklin and
Bohman 1980).
15. Hurricane Frederic tidal floods of September
12-13, 1979 along the Gulf coast, Gulf Breeze-
Fort Barrancas quadrangles, Florida (Franklin
and Scott 1980).
16. Hurricane Frederic tidal floods of September
12-13,1979 along the Gulf coast, Perdido Bay
quadrangle, Florida (Scott and Franklin 1980).
17. Wetlands in Florida (Hampson 1984).
18. Sinkhole type and development in Florida (Sin-
clair and Stewart 1985).
Surface-water Chemistry
1. The pH of water in Florida streams and canal 6. Generalized distribution and concentration of
(Kaufman 1975a). orthophosphate in Florida streams (Kaufman
2. Specific conductance of water in Florida streams 1975d).
and canals (Slack and Kaufman 1975). 7. Temperature of Florida streams (Anderson
3. Dissolved solids in water from the upper part of 1975).
the Floridan aquiferin Florida (Shampine 1975a). 8. Nitrogen loads and concentrations in Florida
4. The chemical type of water in Florida streams streams (Slack and Goolsby 1976).
(Kaufman 1975b). 9. Dissolved-solids concentrations and loads in
5. Color of water in Florida streams and canals Florida surface waters (Dysart and Goolsby
(Kaufman 1975c). 1977).
Ground-water Hydrology
1. Top of the Floridan artesian aquifer (Vernon 4. Principal aquifers in Florida (Hyde 1975).
1973). 5. Estimated yield of fresh-water wells in Florida
2. The observation-well network of the U.S. Geolo- (Pascale 1975).
gical Survey in Florida (Healy 1974). 6. Potentiometric surface of the Floridan aquifer in
3. Piezometric surface and areasof artesianflowof the Northwest Florida Water Management Dis-
the Floridan aquifer in Florida, July 6-17, 1961 trict, May 1976 (Rosenau and Meadows 1977).
(Healy 1975).
(continued)
77
Panhandle Ecological Characterization
Table 4. Concluded
Ground-water Hydrology (concluded)
7. Potential subsurface zones for liquid-waste sto- 10. Potentiometric surface of the Floridan aquifer in
rage in Florida (Miller 1979). the Northwest Florida Water Management Dis-
8. Areasof natural recharge tothe Floridan aquifer trict, May 1980 (Rosenau and Milner 1981).
in Florida (Stewart 1980). 11. Potentiometric surface of the Floridan aquifer in
9. Estimatedpumpagefromground-watersources Florida, May 1980 (Healy 1982).
for public supply and rural domestic use in Flo-
rida, 1977 (Healy 1981).
Ground-water Chemistry
1. Quality of water from the Floridan aquifer in the 6. Depth to base of potable water in the Floridan
Econfina Creek basin area, Florida, 1962. (Toler aquifer (Klein 1975).
and Shampine 1965). 7. Thickness of the potable-waterzone in the Flor-
2. Fluoride content of water from the Floridan idan aquifer (Causey and Leve 1976).
aquiter of northwest Florida, 1963.(Toler 1965). 8. Chemical quality of water used for municipal
3. Chloride concentration in water from the upper supply in Florida, 1975 (Phelps 1978a).
part of the Floridan aquifer in Florida (Shampine 9. Quality of untreated water for public drinking
1975b). supplies in Floridawith reference tothe National
4. Hardness of water from the upper part of the Primary Drinking Water Regulations (Hull and
Floridan aquifer in Florida (Shampine 1975c). Irwin 1979).
5. Sulfate concentration in water from the upper
part of the Floridan aquifer in Florida (Shampine
1975d).
Water Use
1. Estimated water use in Florida, 1965 (Pride 5. Consumptive use of freshwater in Florida,
1975). 1980 (Leach 1982b).
2. Principal uses of freshwater in Florida, 1975 6. Estimated irrigation water use in Florida, 1980
(Phelps 1978b). (Spechler 1983).
3. Freshwater use in Florida, 1975 (Leach 1978). 7. Projected public supply and rural (self-
4. Estimated water use in Florida, 1980 (Leach supplied) water use in Florida through year
1982a). 2020 (Leach 1984).
The USGS also carried out similar investigations
of water resources in Okaloosa County in a study
which included portions of western Walton County
(Trapp et al. 1977). This study was prompted by the
declining level of the upper Floridan Aquifer within
the area. This area depends almost entirely upon
this aquiferfor itswater supply. The study concluded
that levels would continue to decline until wells were
betterdistributed, and alternate water sources, such
as the Sand and Gravel Aquifer or surface waters,
were placed into operation. This report includes a
good description of the drainage conditions through-
out the region. These conditions vary widely be-
cause a number of different physiographic regions
and soil types are found within the area.
These USGS studies on the western Panhandle
were updated by later publication of a hydrologic
budget for Escambia County (Trapp 1978), of hydro-
logic and water quality data for Okaloosa, Walton,
4. Hydrology and Water Quality
and southeastern Santa Rosa Counties (Wagner et
al. 1980) and in a study of the hydrology of the coast
of Okaloosa and Walton Counties (Barr et al. 1985).
The USGS has produced many maps depicting
ground-water hydrology and water quality in the
Panhandle. These are listed in Table 4. In addition
to the USGS studies, the NWFWMD has performed
ground-water studies of the quality and availability of
water from the Sand and Gravel Aquifer in southern
Santa Rosa County (Pratt and Barr 1982), the hydro-
geology of the Sand and Gravel Aquifer in southern
Escambia County (Wilkins et al. 1985), and the
hydrogeologic effects of solid-waste landfills in
northwest Florida (Bartel and Barksdale 1985). The
NWFWMD has also compiled a ground-water bibli-
ography with geological references for the district
(Wagner 1985).
The lack of separation between surface and
ground water in most of the Panhandle, especially in
those areas where springs abound, cannot be over
emphasized. The direct connections can easily be
verified by observing local wells and springs during
moderate to high waterperiods. Atthese times, well
waters and springs are often brown from the tannic
acid of surface waters, and some springs can be
seen to be acting as siphons, draining surface wa-
ters to the underlying aquifer (Figure 49).
Within the Panhandle, ground-water pumping
has lowered the potentiometric surface of the Flori-
dan Aquifer significantly only in coastal Okaloosa
County (Figure 52). In this region, the surface of the
aquifer declined approximately 27 m between 1940
and 1961 (Barraclough and Marsh 1962) and an-
other 12 m between 1961 and 1972 (Healy 1982).
This permitted saltwater intrusion and contamination
of area water supplies. Relocation of wells farther
inland and other measures reducing the withdrawal
of ground water have resulted in a partial rise in the
surface of the aquifer in this area. However, water
levels in 1980 were still as much as 33.5 m below
1940 levels (Wagner et al. 1984). Ground-water
pumping for irrigation in southwest Georgia in-
creased 500% between 1973 and 1980 (U.S. EPA
1983); this withdrawal has been documented as
affecting nearbywells and surface waterflow, includ-
ing that of Panhandle rivers with basins in that area
(FDER 1986c).
Ensuring continuing water supplies requires
regulation by governmental authorities because the
hydrology and water quality of Panhandle ground
waters are wide-reaching phenomena which do not
respect private boundaries. We encourage the con-
tinuing public purchase of major ground-water re-
charge areas as the best long-term solution to maxi-
mizing recharge while protecting water quality.
4.7 Basin Hydrology and Water
Quality
4.7.1 Ochlockonee River Basin (Figure 53)
The Ochlockonee River and its numerous tribu-
taries drain approximately 5,830 km2, of which 52%
(3,030 km2) is in Georgia and 48% (2,800 km2) in
Florida (Foose 1980). Within Florida, the Ochlock-
onee River basin cuts through two physiographic
divisions, the red clay of the Tallahassee Red Hills in
the north and the sandy Gulf Coastal Lowlands in the
south (Puri and Vernon 1964). The Ochlockonee
and its major Florida tributary, the Sopchoppy, have
been designated Outstanding Florida Waters
(OFW-no significant degradation permitted).
Approximately 105 km down the river's 180-km
course through Florida, the Jackson Bluff Dam
backs the river up to form Lake Talquin. This dam
was operated as a hydroelectric generation plant
from 1930 to 1970 and was reactivated in 1985. The
operation of the powerplant turbines can cause
substantial drops in lake level over short periods of
time; as a result their use is being limited to that
producing drops of less than 1 ft below normal
(nongenerating) levels. Lake Talquin is listed by
Myers and Edmiston (1983) as one of the top 50
lakes in the State needing preservation and protec-
tion. The river drops about 27 m from the Georgia
border to the coast (Pascale and Wagner 1982).
Above the dam the river is characterized by sharp
bends and low banks with an average fall of 0.14 m/
km. Below the dam the river widens and passes
through wide bottomlands and marshes, becoming
tidal 19 km from the mouth. Much of the river basin
below the dam (about 910 km2) is contained in the
Apalachicola National Forest and portion (about 65
km2) near the mouth is in the St. Marks National
Wildlife Refuge.
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PAGE 1
ALABAMA / FWS Biological Report 88(12) OCS Study MMS 88-0063 An Ecological Characterization of the Florida Panhandle ,p,, c ct\$-.% 1 *J ". U.S. Department of the Interior Fish and Wildlife Service and Minerals Management Service
PAGE 3
FWS Biological Report 88(12) OCS Study MMS 88-0063 An Ecological Characterization of the Florida Panhandle Authors Steven H. Wolfe Jeffrey A. Reidenauer State of Florida Department of Environmental Regulations Tallahassee, Florida and D. Bruce Means The Coastal Plains Institute Tallahassee, Florida Prepared under Interagency Agreement 14-1 2-0001 -30037 Published by U.S. Department of the Interior Fish and Wildlife Service, Washington Minerals Management Service, New Orleans October 1988
PAGE 4
DISCLAIMER The opinions and recommendations expressed in this report are those of the authors and do not necessarily reflect the views of the U.S. Fish and Wildlife Service or the Minerals Management Service, nor does the mention of trade names constitute endorsement or recommendation for use by the Federal Government. Library of Congress Cataloging-In-Publication Data Wolfe, Steven H. An Ecological characterization of the Florida panhandle. Biological report ; 88 (12)) 6 upt. of DOCS. no. : 149. 89/:88(12) "Performed for U.S. Department of the Interior, Fish and Wildlife Service, Research and Development, National Wetlands Research Center, Washington, D.C. and Gulf of Mexico Outer Continental Shelf Office, Minerals Management Service, New Orleans, LA." "October 1988." Bibliography: p. 1. Ecology--Florida. 2. Natural history--Florida. I. Reidenauer, Jeffrey A. II. Means, D. Bruce. Ill. National Wetlands Research CenterJU.S.) IV. Unitec! States. Minerals Management Service. Gulf of exlco OCS Reg~on. V. Title. VI. Series: Biological report (Washington, D.C.) ; 88 (12) Suggested citation: Wolfe, S.H., J.A. Reidenauer, and D.B. Means. 1988. An ecological characterization of the Florida Panhandle. U.S. Fish Wildl. Serv. Biol. Rep. 88(12); Minerals Manage. Serv. OCS Study\MMS 88-0063; 277 pp.
PAGE 5
PREFACE This report is one in a series that provides an ecological description of Florida's gulf coasts. The watersheds described herein, with their myriad subtropical communities, produce many benefits to people. The maintenance of this productivity through enlightened resource management is a major goal of this series. This report will be useful to the many people who have to make decisions regarding the use of the natural resources of the area. Any questions or comments about or requests for this publication should be directed to the following: Information Transfer Specialist National Wetlands Research Center U.S. Fish and Wildlife Service NASA Slidell Computer Complex 1010 Gause Boulevard Slidell, Louisiana 70458 Public Information Unit (OPS-3-4) Gulf of Mexico OCS Region Minerals Management Service 1201 Elmwood Park Boulevard New Orleans, Louisiana 701 23-2394
PAGE 6
CONVERSION FACTORS Metric to U.S. Customary Multiply by To Obtain millimeters (mm) ............................. 0.03937 ............................ ~nches centimeters (cm) ................ 0 3937 ............................. inches meters (m) ...................................... 3.281 .............................. feet kilometers (km) ............................... 0.6214 .............................. miles square meters (mz) ....................... 10.76 ................................. square feet square kilometers (kmz) .................. 0.3861 uare miles hectares (ha) ................................ 2.471 ................................ acres .............. liters (I) .......................................... 0.2642 ...............g allons cubic meters (ma) ......................... 35.31 .................................. cubic feet cubic meters (ms) .......................... 0.00081 10 ..................... acre-feet milligrams (mg) ............................... 0.00003527 ...................... ounces grams (g) ....................................... 0.03527 .......................... ounces kilograms (kg) ....................... .. .... 2.205 ................................. ounds metric tons (mt) ........................ 2205.0 ..................... .............p ounds metric tons (mt) ........................ 1.1 02 ............................... short tons kilocalories (kcal) ............................ 3.968 .............................. BTU Celsius degrees ................ 1.8("C) + 32 ...................... Fahrenheit degrees U.S. Customarv to Metric Multiply by To Obtain inches ........................................ .25.40 ................................. millimeters inches ................................ 2 54 ................................. centimeters .............................. feet (ft) .......................................... 0.3048 meters ............................ .......................................... fathoms 1.829 meters miles (mi) ...................................... 1.609 ................................ kilometers nautical miles (nmi) ....................... 1.852 ........................... kilometers square feet (It?) ............................... 0.0929 .............................. square meters .......................... acres .......................................... 0 4047 hectares ........................... .............................. square miles (mi.) 2.590 square kilometers ........................ gallons (gal) ................................... 3.785 liters cubic feet (It,) ............................... 0.02831 ........................... cubic meters acre-feet ................................... 1233.0 ................................... cubic meters ............... ounces (02) ................................. 28.35 .................g rams pounds (Ib) ..................................... 0.4536 ............................. kilograms short tons (ton) ........................... 0.9072 .............................. metric tons BTU ................................................ 0.520 .............................. kilocalories Fahrenheit degrees ...................... 0.5556("F -32) ............... .Celsius degrees
PAGE 7
CONTENTS Page PREFACE ............................................................................................................................................... iii CONVERSION TABLE ............................................................................................................. iv FIGURES ...................................................................................................................................... xiii TABLES ................................................................................................................................................ xvi ACRONYMS ......................................................................................................................... xviii ACKNOWLEDGMENTS .................................................................................................................. xix Chapter 1 Introduction .............................................................................................. 1.1 Purpose and Organization 1 .......................................................................... 1.2 The Florida Panhandle: Overview 1 Chapter 2 Geology and Physiography 2.1 Introduction ........................................................................................................................ 3 ...................................................................................... 2.2 Structure and Geologic Setting 5 2.3 Stratigraphy ................................................................................................................ 8 .................................................................................... 2.3.1 Igneous and Paleozoic Rocks 8 2.3 2 Mesozoic Era .......................................................................................................... 8 .................................................................................................... 2.3.3 Cenozoic Era 9 ................................................................................................ a Paleocene Series 9 b Eocene Series .................................................................................................... 9 c Oligocene Series ..................................................................................... 10 ............................................................................. d Miocene and Pliocene Series 11 ...................................................................................... e Pleistocene to Recent 14 2.4 Physiography 2.4.1 The Northern Highlands ......................................................................................... 16 2.4.2 1-he Marianna Lowlands .......................................................................... 17 ...................................................................................... 2.4.3 The Gulf Coastal Lowlands 17 2.5 Regional Marine Geology ...................................................................................... 18 2.6 Local Marine Geology 2.6.1 Ochlockonee Bay .................................................................................................. 23 2.6 2 Apalachicola Bay .......................................................................................... 24 ........... 2.6.3 St Joseph Bay 24 ........................................................................................... 2.6.4 St Andrew Bay System 24 2.6.5 Choctawhatchee Bay System ................................................................................. 26 2.6.6 Pensacola Bay System ......................................................................... 26 2.7 Offshore (Outer Continental Shelf) Oil and Gas Reserves .............................................. 27 V
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Panhandle Ecological Characterization Chapter 3 Climate 3.1 Introduction ...................... ... ........................................................................................... 30 3.2 Climatological Features 3.2.1 Temperature .......................................................................................................... 30 3.2.2 Rainfall ................................ .... ............................................................................. 33 3.2.3 Winds a Normal wind patterns ......................................................................................... 34 b Hurricanes, tornadoes, and waterspouts ............................................................. 39 3.2.4 Insolation ........................................................................................................... 40 a Seasonal changes .......................... .. ................................................................. 40 b Atmospheric screening ....................................................................................... 41 3.2.5 Relative Humidity ................... .. ........................................................................ 42 3.3 Effects of Climate on Ecosystems .................................................................................... 43 3.4 Major lnfluences on Climate 3.4.1 Natural lnfluences on Climate ..................................................................... a Long-term influences on climate -44 b Short-term influences on climate ................................................................... 44 3.4.2 Anthropogenic Influences on Climate .................................................................. 45 3.5 Summary of Climatic Concerns .................................... ... .................................................. 46 3.6 Areas Needing Research .......................... .. .................................................................. 47 Chapter 4 Hydrology and Water Quality 4.1 Introduction ...................................................................................................................... 48 4.1 1 Hydrology ................................................................................................................. 48 4.1.2 WaterOuality ............................................ ... .................................................... 50 a Direct importance ............................................................................................ 54 b Indirect importance ........................................................................................... 54 4.1 3 Hydrology and Water Oual~ty Regulation and Management .................................... 54 4.2 Water Quality Parameters 4.2.1 Dissolved Oxygen (DO) a DO capacities ..................................................................................................... 56 b Oxygen uptake respration ............................................................................... 56 c Oxygen uptake Biochemical Oxygen Demand (BOD) ..................................... 57 4.2.2 pH ............................ .. ............................................................................................ 57 4.2.3 Turbidity and Sediments .......................................................................................... 59 4 2.4 Dissolved Solids ................................................................................................... 59 a Alkal~nity ............................................................................................................. 60 b Hardness ........................................................................................................... 60 c Salinity ....................................................................................................... 60 d Nutrients .............................................................................................................. 61 4.2.5 Temperature ............................................................................................................. 62 4 2 6 Other Contents .................................................................................................. 62 4.3 Major Influences on Surface Water 4.3 1 Major lnfluences on Surface-water Hydrology a Natural factors affecting inland surface-water hydrology .................................... 63 b Natural factors affecting coastal surlace-water hydrology ................................... 65 c Anthropogenic factors aflecting inland surface-water hydrology ......................... 67 d Anthropogenic factors affecting coastal surface-water hydrology ....................... 67 vi
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Contents Chapter 4 Hydrology and Water Quality (continued) Page 4.3.2 Major lnfluences on Surface-water Quality .......................................... a Natural factors affecting inland surface-water quality 67 ........................................ b Natural factors affecting coastal surface-water quality 68 .............................. c Anthropogenic factors affecting inland surface-water quality 68 ............................ d Anthropogenic factors affecting coastal surface-water quality 69 . 4.4 Major lnfluences on Ground Water 4.4.1 Major lnfluences on Ground-water Hydrology ............................................... a Natural factors affecting ground-water hydrology 69 .................................... b Anthropogenic factors affecting ground-water hydrology 69 4.4.2 Major lnfluences on Ground-water Quality a Natural factors affecting ground-water quality ................................................... 71 ......................................... b Anthropogenic factors alfecting ground-water quality 72 .................................................. 4.5 Area-wide Surface-water Hydrology and Water Quality 72 4.6 Area-wide Ground-water Hydrology and Water Quality ................................................. 76 4.7 Basin Hydrology and Water Quality 4.7.1 Ochlockonee River Basin ....................................................................................... 79 4.7.2 Coastal Area between Ochlockonee and Apalachicola Rivers ................................ 84 ..................................................................................... 4.7.3 Apalachicola River Basin 85 4.7.4 Chipola River Basin ................................................................................................ 90 ............................................................................ 4.7.5 St Andrew Bay and Coastal Area 92 4.7.6 Choctawhatchee River Basin .................................................................................. 94 4 7.7 Choctawhatchee Bay and Coastal Area .................................................................. 96 4.7.8 Yellow River Basin ................................................................................................... 99 4.7.9 Blackwater River Basin ................................................................................... 97 ......................... ......... 4.7.10 Escambia River Basin 101 4.7.1 1 Escarnbia Bay and Coastal Area ........................................................................... 102 4.8 Potential Hydrology and Water Quality Problems ............................................................................................ 4.8.1 Hydrologic Concerns 104 4.8.2 Water Quality Concerns .................................................................................................. a Surface water 106 .................................................................................................... b Ground water 107 ChaDter 5 Terrestrial Habitats 5.1 lntroductlon ...................................................................................................................... 109 5.2 Native Habitats .................................................................................... 5.2.1 Longleaf Clayhill Uplands 10 a Flora ................................. ............................................................................... 110 b Ecology .............................................................................................................. 114 .................................................................................................................. c So~ls 117 d Trophic dynamics ................................................................................... 117 e Fauna ............................................................................................................... 118 ......................................................................... f Rare and Endangered Species 118 .................................................................................. 5.2.2 Longleaf Sandhill Uplands 118 a So~ls .................................................................................................................. 118 ...................................................................................................... b Flora 121 .......................................................................................................... c Ecology 121 ............................................................................................................. d Fauna 122 vii
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Panhandle Ecological Characterization Chapter 5 Terrestrial Habitats (continued) Page 5.2.3 Gully Eroded Ravines ............................................................................................ 122 a Soils ................................................................................................................... 122 ............................................................................................................ b Ecology 123 c Flora .................................................................................................................. 124 d Fauna ................... .. ........................................................................................ 124 ......................................................................................................... 5.2.4 Steepheads 125 a Soils ................................................................................................................... 126 b Ecology .............................................................................................................. 126 ................................................................................................ c Flora 126 d Fauna ............................................................................................................... 127 5.2.5 Beech-Magnolia Cl~max Forests ............................................................................ 127 ....................................................................................................... a Soils 127 b Ecology ............................................................................................................. 129 ................................................................................................................. c Flora 130 ..................................................................................... d Fauna ................... .. 130 ............................................. 5.2.6 Longleaf Flatwoods ............................................ .. 132 ................................................................................................................... a Soils 132 b Ecology ............................................................................................................. 132 ................................................................................................................ c Flora 133 ............................................................................................................... d Fauna 133 5.2.7 Beach, Dune, and Scrub ....................................................................................... 137 a Soils .................................................................................................................. 137 ..................................................................................... b Ecology 137 .................................................................................................................. c Flora 138 d Fauna ................................................................................................................ 140 5.2.8 Caves ..................................................................................................................... 140 a Flora .................................................................................................................. 141 b Fauna ......................................................................... 142 5.3 Human-Created Habitats 5.3.1 Fallow Lands, Succession, and Mixed Hardwood Forests ..................................... 142 .................................................................................................................. a Soils 142 b Ecology .............................................................................................................. 142 c Flora .................................................................................................................. 143 d Fauna ................................................................................................................ 143 5.3.2 Silvicultural Communities ....................................................................................... 144 ...... a Soils ......................................................................... 144 b Ecology ....................................................................................... ............ 144 c Flora .................................................................................................................. 144 d Fauna ............................................................................................................. 145 Chapter 6 Freshwater Habitats ..................................................................................................................... 6.1 Introduction 146 6.2 Native Palustrine Habitats ......................................................................... 6.2.1 Herb Bogs and Savannahs 147 a Flora ............................................................................................................. 147 b Fauna ................................................................................................................ 151 6.2.2 Shrub bogs. Titi Swamps, and Bay Swamps ....................................................... 152 a Bay swamps ...................................................................................................... 152 b T~ti swamps ..................................................................................................... 153 c Fauna ........................................................................................................ 154
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Contents Chapter 6 Freshwater Habitats (continued) page 6.2.3 Bottomland Hardwood Forests ............................................................................... 154 a Ecology ............................................................................................................. 156 ...................................................................................................... b Fauna 159 ................................................................................................. 6.3 Native Rlverine Habitats 161 6.3.1 First-order Ravine Streams .................................................................................... 161 a Flora .......................................................................................................... 162 b Fauna ................................................................................................................ 162 6.3.2 Alluvial Streams and Rivers ................................................................................... 162 a Flora ............................................................................................................... 163 b Fauna ........................................................................................................... 163 6.3.3 Blackwater Streams ......................... .... ...................................................... 165 a Flora .................................................................................................................. 165 b Fauna ................................................................................................................ 165 6.3.4 Spring-fed Streams .............................................................................................. 166 a Stream flora ................................................................................................ 167 b Stream fauna ..................................................................................................... 167 6.4 Natlve Lacustrlne Habitats ............................................................................................... 167 6.4.1 Karst Lakes .................................................................................................... 168 a Flora ................................................................................................................ 168 b Fauna .............................................................................................................. 168 6.4.2 River Floodplain Lakes ......................................................................... 169 a Flora ................................................................................................................. 169 b Fauna ............................................................................................................... 169 6.4.3 Swamp Lakes ................................................................................... 169 6.4.4 Ponds ................................................................................................................. 169 a Flora .................................................................................................................. 170 b Fauna ............................................................................... ..... 170 ....................................................................................................... 6.4.5 Coastal Ponds 171 6.5 Subterranean Habitats 6.5.1 Water-filled Caves ................................................................................................. 172 ................................... 6.6 Human-Created Lacustrine Habitats ............... 175 .................................................................................................... 6.6.1 Impoundments 175 a Flora ................................................................................................................. 176 b Fauna .............................................................................. 176 Chapter 7 Estuarine. Saltwater Wetland. and Marine Habitats 7.1 Introduction .................................................................................................................... 178 7.1.1 Tides and Salinity Ranges ......... ............................................ 179 7.2 Estuarine Habltats 7.2.1 Introduction .................................................................................................. 180 7.2.2 Brackish Marshes a Introduction ................................................................................................. 180 b Vascular species ...................................................................................... 180 c Associated fauna .............................................................................................. 180 d Human impacts ................................................................................................. 180 7.2.2 Salt (or Tidal) Marshes a Introduction ........................................................................................... 181 b Major physiographic features ............................................................................ 182 c Distribution ............................... ........ 183 ix
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Panhandle Ecological Characterlzatlon Chapter 7 Estuarine and Marine Habitats (continued) Page d Vascular plants present ................... .. ............................................................ 183 .................................................. e Nonvascular (and microbial) plant community 185 f Marsh-associated fauna .................................................................................... 186 g Species of special concern ................................................................................ 187 h Trophic dynamics/interactions ...................................................................... 187 i Natural impacts ................................................................................................ 189 j Human impacts ................... ... ...................................................................... 189 k Conclusions ....................................................................................................... 190 7.2.3 Intertidal Flats a Introduction ...................................................................................................... 190 b Flora ..................................... ... .......................................................................... 190 c Faunal composition .......................................................................................... 190 d Trophic dynamics and interactions .................................................................... 191 7.2.4 Hard Substrates ...................................................................................................... a Introduction 193 b Community stwcture ......................................................................................... 193 c Trophlc dynamlcs and interactions .................................................................. 193 7.2.5 Oyster Reefs a Introduction ..................................................................................................... 193 b Distr~bution ........................................................................................................ 194 c Oyster autecology ............................................................................................. 195 d Oyster reef development and zonation ............................................................ 196 e Associated fauna .............................................................................. 196 f Commercial aspects .................................................................................... 197 g Natural impacts ................................................................................................. 198 h Human impacts ................................................................................................. 199 i Conclusions ....................................................................................................... 200 7 2 6 Marine Algae a Introduction ........................................................................................................ 200 b Major algal species present ............................................................................. 200 c Associated fauna ............................................................................................. 200 7.2.7 Open Water a Introduction ........................................................................................................ 200 b Species present ................................................................................................ 202 c Recreationally and commercially important specles ......................................... 202 d Species of special concern ................................................................................ 206 e Natural impacts ............................................................................................... 206 f Human impacts ................................................................................................. 206 7.2.8 Subtidal Soft Bottoms a lntroductlon ........................................................................................................ 206 b Physical distribution ................................................................................ 207 c Distribution ........................................................................................................ 207 d Faunal composition .......................................................................................... 207 e Recreationally and commercially important species ......................................... 209 f Trophic dynamics and interactions .................................................................... 210 g Natural lmpacts ....................................................................................... 210 h Human impacts .................................. .. ........................................................... 211
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Contents Chapter 7 Estuarine and Marine Habitats (continued) Page 7.2.9 Seagrass Beds ............................................................................................ a Introduction 211 ................................................... .......................... b Seagrass species present .-213 ......................... ........................................................................... c Seasonality .... 213 d Species succession .......................................................................................... 213 ................................................................................................... e Distribution 215 .............................................................................. f Associated flora and fauna 221 Q Trophic dynamics and interactions .................................................................... 222 ................................................................. h Commercially important species 224 i Naturalimpacts ................................................................................................. 224 j Human Impacts ................................................................................................ 224 7.2.10 Subtidal Leaf Lifter ...................................................................... a Introduction ................ .. 225 b Associated fauna and flora ............................................................................... 226 c Trophic dynamics and interactions ................................................................... 226 ........................................................................................ d Natural impacts 226 ............................................................................................... e Human impacts 226 7.3 Marine Habitats 7.3.1 Hard Substrates ...................................................................................................... a Introduction 227 .............................................................................. b Associated flora and fauna 227 7.3.2 Sandy Beaches ...................................................................................................... a Introduction 228 b Beach zonation ................................................................................................. 228 c Associated fauna ...................................... 228 .............................................................................. d Species of special concern 229 .................................................................. e Trophic dynamics and interactions 229 f Natural impacts .............................................................................................. 230 ................................................ g Human impacts ................................ .230 7.3.3 Marlne Open Water a Introduction ...................................................................................................... 231 .................................................................................... b Species present 231 c Recreationally and cornmcrcially important species ........................................ 231 d Species of special concern ................................................................................ 234 ............................................................................................ e Natural impacts 234 f Human impacts ............................................................................ 235 7.3.4 Artificial Reefs a lntroductlon ............................................ ............................... 235 b Distribution .................................................................................................. 236 ................................................. c Associated fauna ............................. .236 ................................................................. d Trophic dynamics and interactions 238 7.3.5 Subtidal Rocky Outcroppings/Natural Reefs a Introduction ......................................................................... ................ 238 b Associated flora and fauna .............................. .. ............................................ 239 7.3.6 Subtldal soft Bottoms a Introduction ......................... .............................................................................. 239 b Physical description .............................................................. ...... 239 .................................................................................................. c Fauna present 239 d Trophic dynamlcs and ~nteractions ...................... .. .......................................... 241 e Natural impacts ..................................................................................... 241 f Human impacts 241 xi
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Panhandle Ecological Characterization Chapter 8 Summary .............................................................................................. 8.1 The Panhandle in Review 242 .................... 8.2 Panhandle Findings ......................................... 243 8.3 The Panhandle Tomorrow ................................................................................................ 246 ..................................................................................................................... LITERATURE CITED 249 APPENDIXES A Federal. State. and Local Environmental Control Agencies and Their ....................................... Responsibilities ................................... 275 ......................................... B Panhandle Regulatory Agency Locations and Addresses 277 xii
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FIGURES Page Chapter 1 Introduction .......................................................................... 1 Florida Panhandle drainage basins and features 2 Chapter 2 Geology 2 Terraces in the Florida Panhandle formed by previous sea-level stands .................... .. ............... 4 3 Major structural features of the Florida Panhandle ..................................................................... 5 ..................................................................................... 4 Surface geology of the Florida Panhandle 7 ....................................................................................... 5 Physiography of the Florida Panhandle 15 6 The thickness of Eocene to Recent sediments along the Panhandle coast from ................................................................ Choctawhatchee Bay to the Alabama-Florida border 20 ............................... 7 Coastal energy levels and tidal ranges for the northeastern Gulf of Mexico 21 .................................................... 8 Schematic of net littoral drift along "idealized" Panhandle coast 21 9 Nearshore bottom topography off Choctawhatchee Bay showing sand body features .................. 22 10 Stratigraphy of coastal region from Cape San Blas to Ochlockonee Bay ................................ 23 ....................................................................... 11 Surface sediment composition in St Joseph Bay 25 12 Generalized geologic column of format~ons in the western ponions of the Florida Panhandle ...... 28 13 OCS leases in the Pensacola and Destin Dome Blocks off shore from west Florida 29 Chapter 3 Climate ...................................... 14 Locations of NOAA climatological stations in the Florida Panhandle 30 ........ 15 Isotherms for mean maximum and mean minimum July temperatures in Florida Panhandle 31 16 lsotherms for mean maximum and mean minimum January temperatures in Florida Panhandle 32 ............................................. 17 Seasonal rainfall variation at selected sites in Florida Panhandle 33 18 Panhandle average annual rainfall and NOAA climatolog~cal station locations ........................... 34 ....................................................... 19 Panhandle maximum and minimum twelve-month rainfall 35 ..................... 20 Percent of total daily rainfall during individual hours of the day at Tallahassee 36 21 Occurrence of extended dry per~ods at Tallahassee and Pensacola 1950-80 ............................. 36 22 Low level (600-900 m) winds ............................................................................................... 37 23 Percentage of time wind blew from different directions in Flor~da Panhandle during spring and summer, 1959-79 average ....................................... ....... .......................... 38 24 Percentage of time wind blew from different directions in Florida Panhandle during fall and winter, 1959-79 average ...................................................................... 38 .................................... 25 Seasonal windspeed at selected sites in Florida Panhandle 38 26 Paths of hurricanes striking the Panhandle coast, 1885-1985 .............................................. 39 27 Change in length of atmospheric light path with change in distance above or below orbital plane 40 28 Change in light intensity at Earth's surface with change in distance above or below orbital plane 10 29 Mean daytime sky cover and Tallahassee cloud cover frorn 3 years of satellite data ............... 41 xiii
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Panhandle Ecological Characterization Chapter 3 Climate Page 30 Variations in insolation striking the atmosphere depending on latitude and season ...................... 42 .............................................................. 31 Monthly insolation at selected sites in Florida Panhandle 43 ................................. 32 Mean percent of possible sunshine at selected sites in Florida Panhandle 43 33 Increasing atmospheric carbon dioxide as measured atop Mauna Loa Hawaii ...................... ..... 46 Chapter 4 Hydrology and Water Quality ............................................................................ 34 The basic hydrologic cycle ........................... .. 49 ................................................................ 35 Panhandle drainage basins discussed in this document 50 ........................................................................ 36 Out-of-State drainage basins of Panhandle rivers 51 37 Primary Panhandle aquifers used as water sources ...................................................................... 52 ................................................................................ 38 Hydrologic cross sections of the Panhandle 52 ............................... 39 Potentiometric surface of the Floridan aquifer in the Panhandle in May 1980 53 .................................... ...................... 40 Recharge areas to the Floridan aquifer in the Panhandle .... 53 41 Oxygen solubility as a function of temperature. ....................................................................... 56 42 Oxygen solubility as a function of salinity ....................................................................................... 56 43 Minimum pH of Panhandle surface waters ............................................................................... ..58 ............................................... 44 Concentrations of dissolved solids in Panhandle surface waters 59 45 Seasonal riverflow in two Florida Panhandle rivers ...................................................................... 63 46 Apalachicola River flow and rainfall at City of Apalachicola ............................................................ 63 ............................................................... 47 Locations and magnitudes of major Panhandle springs 64 48 (A) Formation of a salt wedge and "stacking" of freshwater layer to right of flow direction at river mouths (6) Coriolis and geostrophic forces affecting fresh water flowing from river mouths ....................................................................................................................................... 66 49 Generalized relationship of surface water to ground water for springs and siphons ...................... 70 50 Location of limestone aquifers known to be within 50 fl of land surface and of .............................................................................. surficial beds of low water permeability 73 51 Seasonal fluctuations in air temperature at Tallahassee and Sanford Fire Tower and in water temperature of Sopchoppy Rlver, June 1964 to September 1968 .................................... 75 52 Potentiometric surface of the Floridan aquifer in 1940 and 1980 before and after increased ground-water pumping in the area of western Choctawhatchee Bay ........................ 80 53 Eastern Panhandle drainage basins-Ochlockonee River. Coastal area between Ochlockonee River and Apalachicola River, Apalachicola River, and Chipola River .................. 81 54 East-central Panhandle drainage baslns-St Andrew Bay and Choctawhatchee River ............... 93 55 West-central Panhandle drainage basins4hoctawhatchee Bay and Yellow River ..................... 97 56 West Panhandle drainage basins-Blackwater River Escambia River and Escambia Bay ........ 100 57 Projected sea-level rise using different scenarios .................................................................. 106 58 Diagram showing Bruun Rule for beach erosion following increase in sea level .......................... 106 Chapter 5 Terrestrial Habitats 59 Vegetative communities of the Florida Panhandle ................................................................... 11 60 Stream habiat classification .......................................................................................... 123 61 Distribution of known steepheads in the Florida Panhandle ......................................................... 125 62 Pine-hardwood continuum developed over a steep slopelmoisture gradient ............................... 128 Chapter 6 Freshwater Habitats 63 Flatwoods seepage bog developed along a gentle slopelmoisture gradient ................................ 148 64 Flatwoods savannah. a special case of a seepage bog that is underlain by silt and hav~ng a nearly level slope .................................................................................................................. 149 xiv
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Figures Chapter 6 Freshwater Habitats (continued) Page 65 Relative leaf productivity per stem biomass of 11 major leaf-fail producers (trees) in the .............................................................................................. Apalachicola River flood plain 158 ..................... 66 Mean monthly leaf fall of three representative species of intensive-transect plots 159 67 Decline in carbon. phosphorus. nitrogen. and total leaf mass during decomposition in Apalachicola River system ...................................................... 160 ....................................................... 68 Distribution of caves and phreatobltes in Panhandle Florida 173 69 Regional structure of eastern Panhandle Fiorida showing the Gulf Trough putative barrier ............................ to dispersal between the Chattahoochee and Woodviile phreatobite faunas 174 Chapter 7 Estuarine. Saltwater Marsh. and Marine Habitats 70 Schematic vlews of gulf coast salt marshes on protected low-energy shorelines and ........................................................................................... open moderate energy shorelines 184 .................................... 71 Horizontal distribution of macrofauna in a typical Panhandle tidal marsh 186 72 A cross-sect~onal view through a typical inteflidal sand-flat community in the Panhandle ....................................................................................... showing representative invertebrates 191 73 Seasonal stone crab densities on a Panhandle oyster reef ......................................................... 198 ................................................... 74 Stone crab age-group occurrence on a Panhandle oyster reef 198 75 Seasonal variation of the spionid polychaete Prionospiopygmaea in a St George Sound ................................. ................................................................ subtidal soft-bottom habitat -.. 209 76 Variat~on in a five-slotted sand dollar (Meiiita quinquiesperforata) population from ............................................................................................................. St George Sound 210 .................................................. 77 Yield of penaeid shrimp and vegetation coverage in an estuary 212 .................................................. 78 Four common seagrass species present in Pantiaridle waters 214 79 Diagram of a typical Thaiassia shoot ........................... .... ........................................................ 215 80 D~agram showing typical depth distributions of three seagrass species and a common brackish species Ruppla maritima ........................................................................................ 216 81 Ecosystem development in seagrasses .................................................................................... 217 82 Idealized sequence of sengrass recolonizdtion and growth after a large disturbance ................. 217 83 Seagrass distribution in St Joseph Bay in 1981 ...................................................................... 219 ............................................... 84 Seagrass d~slribution in a portlon of the Pensacola Bay system 220 85 Schematic view showing the numerous seagrass epiphyte interactions that occur in a seagrass bed and the irnportaiit physical factors affecting the interactions ............................. 223 86 Seasonal abundances of leaf-litter associated invertebrates from the Apalachicola Bay ................................................................................................................ system In 1976 226 ....................... 87 A high-energy beach corrlmunity, stiow~ng major zones relating to sand motion 228 ....................... 88 Change in Panama City beach profile after Hurricane Eloise in September 1975 230 ..................................... 89 Seasonal phytoplankton abundances in the northeast Gulf of Mexico .... 232 ........................ 90 Correlation of pelagic fisheries to changes in air temperatures off Panama City 233 91 Artificial reef locations in Panhandle waters ........................... .. ............................................ 237 92 Cross-sectional view through a typical rocky outcropping off the Panhandle coast ................... 240 Chapter 8 Summary .......................................................................... 93 1980 Florida Panhandle population distribution 244 ........ 94 1980 Florida Panhandle population density and projected popuiat~on increase 1980-2000 247
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TABLES Page Chapter 3 Climate 1 Panhandle thunderstorm frequency statistics ................................................................................... 36 2 Total number of hurricanes striking the Florida Panhandle during 1885-1985 ................................ 40 Chapter 4 Hydrology and Water Quality 3 Drainage basin statistics for major Florida Panhandle ..................................................... 74 4 U.S. Geological Survey maps for the Florida Panhandle ................................................................. 77 5 Scenarios of future sea-level rise .................................................................................................. 105 Chapter 5 Terrestrial Habitats 6 Endangered and threatened plants of Panhandle Florida and counties where they are found ...... 112 7 Endangered and threatened vertebrate animals of Panhandle Florida .......................................... 114 8 Numbers of amphibians and reptiles captured on two annually burned pine stands and an unburned hardwood stand in north Florida ................................................................................. 119 9 Breeding birds of clayhill longleaf pine old-growth forest ............................................................... 120 10 Species of trees in the beech-magnolia forest association in the Panhandle ................................ 130 11 Comparison of floral diversity among four flatwoods sites in Panhandle Florida ........................... 134 Chapter 6 Freshwater Habitats 12 Types. species composition. and distinguishing characteristics for bottomland hardwood ............................................................................................. forests of the Apalachicola River 155 13 Species abundance for all forest types combined .......................................................................... 157 14 Common macrophytes of Lake Seminole ..................................................................................... 176 Chapter 7 Estuarine. Saltwater Wetland. and Marine Habitats 15 Definition of the estuarine and marine systems ............................................................................ 179 16 Common benthic macroinvertebrates found in bracklsh vegetation in the Panhandle ................... 181 17 Common vascular plants present in Panhandle salt marshes ...................................................... 182 18 Zonal relationship of algae with spermatophyte community in Panhandle marshes .................... 185 19 Common InveRebrateS of Panhandle salt marshes ........................................................................ 186 20 Common fishes of Panhandle salt marshes ............................................................................. 187 21 Common reptiles of Panhandle salt marshes ................................................................................. 187 22 Common birds of Panhandle salt marshes .................................................................................. 188 23 Common mammals of Panhandle salt marshes ........................................................................... 189 24 Commonly encountered macroinvertebrates of Panhandle intertidal flats ..................................... 192 25 Common birds of Panhandle intertidal tlats .............................................................. 192 26 Common decapods found on Panhandle jetties ........................................................................... 194 27 Area of oyster reefs (beds) in the Florida Panhandle ................................................................... 194 xvi
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Tables Chapter 7 Estuarine and Marine Habitats (continued) Page 28 Common fauna of a Panhandle oyster reef .................................................................................... 197 29 Oyster landings from Choctawhatchee Bay.196 5.82 ..................................................................... 198 30 Common algal species in the Panhandle ....................................................................................... 201 31 Common planktonic organisms found in Panhandle estuarine open waters ................................ 203 32 Common nektonic forms found in Panhandle estuarine open waters ........................................... 204 ........ 33 Demersal fish. skates. and rays commonly encountered in Panhandle soft-bottom habitats 207 34 Abundant or common benthic meiofauna in Panhandle soft-boftom habitats ................................ 208 35 Abundant or common benthic macroinvertebrates in Panhandle soft-bottom habitats .................. 208 36 Surface area of major water bodies and most recent seagrass distribution estimates for the Panhandle water bodies ........................................................................................................ 218 37 Dominant epiphytic organisms that grow on seagrass blades ....................................................... 221 38 Dominant mobile fauna within the seagrass leaf canopy .............................................................. 222 39 Dominant epibenthic and infaunal invertebrates that live on or within the sediments of seagrass meadows ..................................................................................................................... 222 40 Common fauna of Panhandle leaf litter habitats ........................................................................... 226 41 Common macroinvertebrates present on Panhandle beaches ................................................... 229 42 Common seabirds and shorebirds present along Panhandle beaches ...................................... 229 43 Common plankton present In The marlne open-water habitat of the Panhandle ............................ 231 44 Common fish species present in marine open waters of the Panhandle ...................................... 232 45 Marine turtles with special status that occur in Panhandle marine waters .................................... 233 46 Charter and party boat principal ports of call ............................................................................... 233 47 Shipwrecks in Florida Panhandle waters ........................................................................................ 238 48 Some resident reef fish from eight artifical reefs off Panama City. Florida ..................................... 238 49 Common invertebrates present in nearshore soft-bottom habitats in the Panhandle .................. 241 xvii
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ACRONYMS State and Federal agencies and programs A-C-F ANF FDA FDER FDNR FNAl FREAC HRS IFAS NMFS NOAA NPDES NWFWMD OCS OFW S R USACE USFWS USGS Apalachicola-Chipola-Flint Rivers Apalachicola National Forest U.S. Food and Drug Administration Flor~da Department of Environmental Regulation Florida Department of Natural Resources Florida Natural Areas Inventory Florida Resources and Environmental Analysis Center Florida Department of Health and Rehabilitative Services Institute for Food and Agricultural Service, University of Florida National Marine Fisheries Service National Oceanic and Atmospheric Administrat~on National Pollution Discharge Elimination System Northwest Florida Water Management District Outer Continental Shelf Outstanding Florida Water State Route United States Army Corps of Engineers United States Fish and Wildl~fe Service United States Geological Survey xviii
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ACKNOWLEDGMENTS The authors wish to thank the following persons for their contributions: Carol Knox, Elizabeth Woodsmall, Steve Bradley, graphics; Lorna Sicarello, U.S. Fish and Wildlife Service, review and documents; the staffs of the Northwest Florida Water Management District, the Environmental Protection Agency's Gulf Breeze Laboratory, and the National Marine Fisheries Service's Southeast Fisheries Center (including Librarian Rosalie Vaught and Director Eugene L. Nakamura); Jim Muller, Florida Natural Areas Inventory, marine and estuarine habitat information; Henry Bittaker, seagrass information; Dr. Richard Iverson, prepublication seagrass manuscript; Kevin Sherman, review and rneiofaunal information; Dr. Landon Ross and Craig Dye, Florida Department of Environmental Regulation, and Loretta Wolfe, Wolfe Associates, reviews. We owe a special thanks to Dr. Millicent Quammen of the U.S. Fish and Wildlife Service's National Wetlands Research Center for coordinating the reviews and for general assistance and patience far beyond that which is reasonable. We also acknowledge Center employee Dana Criswell for editing. Grateful appreciation 1s extended to the Minerals Management Service's Gulf of Mexico OCS Regional Office for their participation in planning this project and for providing funding to print this document. Dr. Robert Rogers served as Contracting Officer's Technical Representative for the project. Janice Blake, Debbie Miller, and Mike Dorner of that office contributed significantly in coordinating publication. xix
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Chapter 1. INTRODUCTION 1.1 Purpose and Organization The Florida Panhandle isoneof the most rapidly developing regions in the entire State. Coastal cities such as Panama City, Destin, and Pensacola, with their attractive white-sand beaches and clear waters, arethe centersofthis growth. Concomitantwith such growth are rapid alterations in surrounding terrestrial and aquatic habitats caused by increased urbanization, industrialization, sewage and effluent discharge, river flow alteration, stormwater runoff, and dredge and fill activities. Many Panhandle commercial interests, especlally fishing and tourism, are highly dependent upon the maintenance of relatively unaltered habitats. The residents of many smail Panhandle coastal communities such as Apalachicola and Carabelle derive practically all their incomes from the seafood industry. If unregulated growth occurs without regard to environmental impacts, the failure of this economy and the end of a unique way of life may follow. In addition, the destruction of the natural coastal setting would seriously curtail tourism. Critical decisions on the preservation or economic development of particular areas are often made without knowledge of the composition, dynamics, and sensitivity of the local habitats and the associated flora and fauna to perturbations. Additionally, higher level interactions between systems and habitats areoften overlooked. This report is an extensive review and synthesis of available literature on the local physical setting and ecology and a discussion of important impacts on the habitats wlthin the Panhandle region. We have attempted to project possible future impacts and to point out areas that need further research before they are permanently altered. The report is divided into two main sections. Chapters 2,3, and 4 cover the geology and physiography, the climate, and the many aspects of the surfaceand ground-water systems. These chapters provide the physical and chemical background information necessary to understand many of the environmental pressures affecting the biological habitats. These habitats-terrestrial, freshwater, estuarine, and marine-and their inhabitants are described in Chapters 5, 6, and 7. Chapter 8 is a summary of the Panhandle systems and a discussion of their unique aspects as well as of areas that are in need of further investigation. 1.2 The Florida Panhandle: Overview The Florida Panhandle discussed in this report (Figure 1) extends from the Ochlockonee River basin west to tho Florida-Alabama border (not including Perdido River basin and Bay) and north to the Georgia and Alabama borders. Major rivers in the region include the Ochlockonee, Apalachicola, Chipola, Choctawhatchee, Yellow, Blackwater, and Escambia. Major bays and estuarine systems include: Ochlockonee Bay, Apalachicola Bay, St. Joseph Bay, St. Andrew Bay, Choctawhatchee Bay, and Pensacoia Bay. Also discussed are the nearshore Gulf of Mexico waters and the adjacent Continental Shelf region The Panhandle contains a wide variety of surface waters and physiographic regions. Th~s lends it an ecological diversity found in few other areas in the United States. The Panhandle also boasts several of the largest and most productive estuaries inthestate. Localfisher~esandthefisheriesof much of the coastal area depend on the water quality of these estuaries for spawning and nursery grounds. Theirprotection must beof high priority. Many inland
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Panhandle Ecological Characterization 8786" 16" 8 4O I I I I I I ALABAMA L --1, \ 1 GEORGIA --. GULF OF MEXICO A. Ochlockonee R~ver D. Ch~pola R~ver H Yellow R~ver 0 10 20 30 40 50 B. Coastal area between Ochlockonee E St. Andrew Bay J. Blackwater River tand Apnlach~coia Rivers F. Choctawhatchee Rlver K. Escambia River C Apalach~cola R~ver G Choctnwhatchee Bay L. Escarnb~a Bay A Figure 1. Florida Panhandle drainage basins and features. areas are undeveloped and probably will remain so place with no more regard given to habitat destrucin the near future. Other areas, most notably the tion and environmental impact than is given in the western coasts, are undergoing explosive growth south. We hope this document will help produce very similar to that occurring in the southern part of wise decisions concerning the direction and meththe State. Unfortunately, this growth is often taking ods of Panhandle growth.
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Chapter 2. GEOLOGY AND PHYSIOGRAPHY 2.1 Introduction The animals and plants of any region are greatly affected by its geology. Plants are rooted in soils derived from the inorganic rocks or sediments of the earth's surface and are further affected by the slope, moisture-bearing content, chemistry, and physical nature of the sediments. Animals, in turn, are affected by plants as food and shelter. Animals may also respond directly to the geology of a region because they live on the soil surface or burrow in it. The slope, friability, moisture-bearing capacity, and other properties of soils often have as much influence on animals as on plants. The surface geology of Panhandle Florida is entirely sedimentary, comprised of three different types of sediment: limestones, organics, and clastics (silt, clay, sand, gravel). The northern half of the Panhandle is dominated by sandy clays or clayey sands deposited by the alluvial action of rivers and streams. The southern half of the Panhandle, especially in the west, is dominated by sands deposited along ancient shorelines. The surface of the ground in the eastern half of the Panhandle and in the vicinity of Marianna, Jackson County, is influenced by the presence of limestones near the surface which have caused the top of the ground to be modified topographically by various types of subterranean solution activity. In low lying areas (streamcoursesor natural depressions of varying kinds), especially south of Cody Scarp and east of the Choctawhatchee River, peat, muck, and other types of decomposing plant litter are very common. Panhandle Florida has been slowly emerging fromthesea since at least some time inthe Miocene. The age of surface sediments, therefore, is older near the Alabama and Georgia borders and bewmes progressively younger towards present sea level. The floor of each stand of the sea was a relatively flat, gently seaward-sloping terrace when first exposed by the receding shoreline. Terraces are separated from each other by step-like escarpments or by subtle changes in relief (Figure 2). Since their emergence, terraces have been eroded and dissected by streams and rivers. Entire strata have been removed in some areas, and materials from other strata have been deposited on top of lower terraces, and rearranged by the erosive power of water. Fifty-two percent of the open gulf beaches from Mexico Beach to a point due south of Tallahassee have been eroding during historical times (Tanner 1975). In the same time period, 35% have been stable, and only 14% have been growing. An astounding 1 1.2 m per year of beach front has eroded from Cape San Blas between the years 1875 and 1942. Dog Island has been eroding at about 1 m per year, and St. George Island has been lengthening its eastern tip at a rate of about 20 m per year, but the beach face has been eroding at about 1.3 m per year between 1934 and 1970. Given the consensus of scientific researchers that sea level has been rising overthe past century and that a greenhouse effect is now measurable due to increased CO, levels from fossil fuel combustion and other human activities, it seems certain that sea level will continue to rise over the next century. Some geologists have calculated that if all the ice in polar regions and montane glaciers were to melt, the ocean surface would rise at least 100ft. This iscloseto thetopof the Wiwmico terrace, presumably the shoreline at the end of the Pliocene and at the onset of the Pleistocene. The land submerged under the Wicomiw sea (Figure 2) indicates that about one-half of the surface of the Panhandle would be inundated in this scenario.
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2. Geology and Physlography 2.2 Structure and Geologic Setting Three structural features dominate the geology of Panhandle Florida. These are the Gun of Mexico Sedimentary Basin, Chattahoochee Anticline, and the Apalachicola Embayment. The Panhandle from about Okaloosa County westward Is the eastern edge of the Gulf of Mexico sedimentary basin, a negative structural feature (i.e., a depression that receives sediments) whose sediments thicken westward toward the Mississippi River. A positive structural feature (a rise, from which sediments erode) called the Chattahoochee Anticline lies at the eastern end of the negative area, separating it from a smaller negative feature called the Apalachicola Embayment (Figure 3). The Chattahoochee Anticline is aligned southwest to northeast across the northeastern portion of Panhandle Florida (Figure 3), and is very important to the ecology of the region because it brings Oligocene and Eocene carbonate rocks to the ground surface where the physical and chemical properties of the soil and water are greatly affected by the presence of the carbonates. The Apalachicola Embayment and its probable northeastward extension, the Gulf Trough, is a negative structural feature that represents a downfallen block of land, called a graben (Schmidt 1984). This negative feature is important to the biology of the Panhandle because it is strongly affected by the predominantly clastic sediments. Clastics differ greatly from carbonates in their chemistry, physical properties, and weathering. The Apalachicola Embayment (Figure 3) is a relatively shallow basin between the Ocala and Chattahoochee uplifts, narrowest on the northeast and opening up to the south and southwest. The magnitude ofthe basin increaseswithdepth, indicating that it is a long-developing feature. Near the ground surface the Quaternary and Neogene rocks are gently downwarped, but the deeper Paleogene and Mesozoic rocks are downwarped even more, resulting in older strata that are thicker (Murray 1961). Southwardalong itsaxis, the uppersedimentary rocks (Triassic to Recent) of the Apalachicola Ernbayrnent plunge to a depth of nearly 15,000 R before metamorphic Paleozoic rocks are encountered (Applegate et al. 1978). At the eastern limits of CUTT.+~E 0 a 2.3 uIL1s ANTICLINE 0 16 32 KILOMETERS FLORlOI PENINSULA SLDIUCYTAIV LIOYINCE NORTH GULF COAST SCDIYEWTIRI PROYIMCF Figure 3. Major structural features of the Florida Panhandle (from Schmldt 1984).
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Panhandle Ecological Charadarizatlon the Apalachicola Embayment, carbonate sediments rise and are exposed at the ground surface beginning at the eastern edge of Panhandle Florida and cresting along the Ocala Arch of the Florida Peninsula Sedimentary Province in the very northwestern part of peninsular Florida (the Big Bend region). The western Panhandle from about the Choctawhatchee River westward is underlain by westwardly thickening clastic sediments variously bedded as sands, clays, shales, sandstones, and thin limestones. The hard limestones of the central and eastern Panhandle either pinch out or dip deeply west of the Choctawhatchee River and have little or no sulface expression on the landform. The surface sedimentsof the northern half of the Panhandle west of the Choctawhatchee River are crossbedded sands, gravels, and clays called the Citronelle Formation. These are Plioceneto Recent fluvial deposas that are commonly found at elevations above 200 ft. Tan to light-orange clayey sand is found southward towards the coast in the western Panhandle, and probably represents the reworking of someof the higher Citronelle hills during sea level fluctuations. These clayey sands grade into unconsolidated white to light-gray quartz sands of the Pleistocene to Recent coastal terraces. The terrace deposits generally thicken from zero to nearly 100 ft near the coast. The eastern Panhandle is an uneven platform of carbonate bedrock over which has been deposited one or more layers of less consolidatedclastics. The bedrock consists mainly of limestone (calcium carbonate) and sometimes of dolomite (calcium carbonate with varying percentagesof magnesiumcarbonate). lmpuritiesofsand, silt, and clay increase in the limestones going east. Other limestone has beensilicified into layersorveinsof chert orflint. The superficial strata of bedrock date to the Eocene, Oligocene, and early Miocene (Figure 4). The bedrockof the eastern Panhandle has been subjected to considerable solution activity, forming numerous caverns, lime sinks, and other karst features. The clastics consist of sand, silt, clay, shell marl. gravel, rock fragments, phosphate pebbles, and diatomaceous earths. Fossils, including petrified wood, are present in some deposits but absent in others. Sand, silt, and clay are mineral particles defined by their specific diameters. Layers of shells and their degradation products are often common. Clastics with shell marl are mostlythought to representthe sediments of shallow seas and estuaries. These sediments became terrestrial clastics when sea level dropped. The abundance of oyster shells in many shell marls suggests that oyster bars in bays and lagoons were often covered by sediments that later became terrestrial clastics. Diatomaceous earth consists largely of the silicified walls of diatoms that accumulated in marine sediments. Such deposits are also known as pipe day, fuller's earth, and attapulgite. Thick beds are mined commercially in Gadsden County for the production of abrasives andotherproducts. Veins of diatomaceous earth shrink and swell considerably with changes in moisture. This movement requires special foundations for structures buin on terrain containing fuller's earth. Deposition of the various strataof clastics began in the Miocene after the carbonate bedrock had formed. Some of these clastics were once marine sediments of nearshore environments, exposed when the Panhandle was uplifted geologically; others were deposited as alluvium in valleys or as deltaic or estuarine dewsits near river mouths. Otherswerewind-blowndeposits such as dunes and still others were sediments in lake bottoms. The clastic deposits form terraces that slope gently towards the Gulf of Mexico and which are separated from each other either by step-like escarpmentsorby subtlerchanges inrelief. Sincetheir deposition the terraces have been subiected to considerable erosion and dissection by streams and rivers. Entire strata have been removed from some areas, and the materials of other strata have been reworked by erosional processes. Peat deposits are common. Peat consists of dead plant matterwhich may persist forthousandsof years or longer w~thout appreciable decomposition. Peats build up in marshes, swamps, and lake bottoms, whereverlowoxygen conditions prevail, inhibiting organisms of decay. High acidity and low levels
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Panhandle Ecological Characterization of nitrogen may reinforce this inhibition. The oldest peat occurs at the bottom of adeposit, and new peat forms at the surface as dead plant materials accumulate. Other, nonfibrous peat is generally called muck. Most peats contain some sand, sin, or clay that was transported by water or wind from other areas. Well presetved wood commonly occurs in peat. Florida peat deposits and associated vegetation were surveyed by Harper (1910) and Davis (1946). 2.3 Stratigraphy The rocks that underlie the Panhandle range in age from late Precambrian to Recent. The oldest rock exposed in the Panhandle is Eocene limestone of the Crystal River Formation. It is found near the sudace of the ground in northern Holmes and northern Jackson Counties, and is exposed along the upper Chipola River and upper Holmes and Wrights creeks. The rocks of different age that are outcropped in Panhandle Florida are shown in Figure 4. 2.3.1 Igneous and Paleozoic Rocks The igneous rocks of Florida include metabasalts in Volusia County, granites in Lake and Orange Counties, granite and diorite in St. Lucie County, and metabasalt in Hillsborough County (Grasty and Wilson 1967, Bass, 1969, MiRon and Grasty 1969, Milton 1972, Barnetf 1975). Panhandle deep wells have intercepted granite at 12,191 ft in Bay County, described by Applegate et al. (1978) as well-indurated, highly rnicacwus sandstones; argillaceous siltstones; and well-indurated shales. Intheeastern pattof Bay County,the Eagle Mills Formation is probably absent, thinning from about 200 ft in western Bay County. The NorphU, Srnackover and Haynesville Formations are found here, overlying the basal granite. These formations are all Upper Jurassic In age. The Norphlet is 267ft thick and consists of red sandstones, siltstones, and shales. The Smackover Formation is 163ft thickand is composed of limestone and dolomitic limestones. The Smackover Formation was found to have oil locked in a dense impermeable section of limestone and conglomeritic calcareous sarKistone. The next younger formation, the Haynesville, is just over 300 It thick and is composed of red to gray, very well indurated calcareous shales, afew well sorted finegrained sandstones, andafewthin-bedded micrites. All three formations apparently thin westward because only a thin Haynesville section is present in a deep well drilled in western Bay County. West of Bay County these units thicken as they plunge into the Mississippi Embayment. In Bay County, the Eagle Mills Formation is overlain by 2,600 ft of the Cotton Valley Group sediments. This group also overlies the Haynesville section in eastern Bay County (Schmidt and Clark 1980). The Cotton Valley Group is Upper Jurassic in age and is a varicolored mudstone and coarse sandstone. dacite porphyry and granodiorite in Gulf County at 13,000 it, and granite at 14,480 ft below the Surface Above the Cotton Valley sediments are differenin southern Walton County (Barnett 1975). tiated Lower Cretaceous sands and shales, varying from 5,000 to 6,000 ft in thickness. Above these lie The Paleozoic sediments from deep wells in the white sandsof the Lower Tuscaloosa Formation, Florida have been described and correlated by which is Upper Cretaceous in age. Applin (1951), Bridge and Berdan (1952), Cramer (1971), and Barnett (I 975). Strata range in age from he Tuscaloosa Formation consists of nonlate Precambrian to Early Devonian based on fossil ,,in,, gray to green, fine to coarse, poorly sofied evidence. sand and variegated shales underlying a marine member consisting of a gray laminated micaceous 2.3.2 M~SOZO~C Era glauconitic hard shale with shell fragments and carDescriptions of the Mesozoic rocks in the Panbonaceous seams and flecks. On top of this, the handle have been reported by Arden (1974) and Tuscaloosa Formation consists of a gray to cream Applegate et al. (1978). Overlying the Paleozoic fine calcareous micaceous clayey silty sandstone igneous rocks is the Eagle Mills Formation of the with beds of calcareous shale. The thickness of the Triassic Age. This formation contains dikes and sills Tuscaloosa Formation varies but has been reported of basic igneous rocks. Its overall lithology has been to be over 700 ft thick (Puri and Vernon 1964). 8
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2. Geology and Physiography OverlyingtheTuscaloosaFormationin Panhanies from 250 to 750 ft throughout the central Pandle Florida is the Eutaw Formation: gray to cream handle. calcareous fine sandstone that changed downdip into a soft pasty sandy chalk with ~imeStOne Seams. The Midway Formation underliesthe entire FlorIt ranges between 150 and 300 ft in thickness. ida panhandle and extends widely throughout the southeastern Coastal Plain. Regionally, the vertical Above the Eutaw are sediments of the Austin and lateral changes of lithologic character and the Age. These beds are equivalent to the Mooreville thickness of the unit are rather great, as demonChalk in Alabama. In northwest Florida, these sedistrated by Chen (1965). s is isopach-lithofacies ments are gray soft glauconitic micaceous fine-toindicate that the clastic sediments, such as glaucocoarse quartz sand interbedded withgray-green soft nitic and arenaceous shale and sandstones, are calcareous thinbedded clay, averaging 350to 450ft ,re dominant around the Chattahoochee Arch thick. Generally less than 500 ft in thickness, beds than elsewhere in the Panhandle. In addition, calof the Taylor Age overlie the Austin Age beds. The careous shale is a major lithologic component that uppermost cretaceous sediments are beds of the occurs over most of the Panhandle region except in Navarro Age. The Presence of these sediments is the southeastern area (Wakulla and southern Leon questionable in northwest Florida, but a thin gray Counties), where limestone is predominant. pasty marloccurs at the top of the Taylor beds in the western Panhandle. b. Eocene Series. The Eocene Series in the The Mesozoic sediments total approximately southeastern Gulf Coastal Plain has been divided in combinedthickness in the vicinity of Bay into three stages. These stages are the Wilcox County, The first occurrence is generally deeper Stage. which is Lower Eocene;the Claiborne Stage, than 3,000 ft below sea level, and the sequence which is Middle Eocene: and the Jackson Stage, continues downward to about 13,000 ft below sea Which is Upper level. The Wilcox Staae has been divided into three 2.3.3 Cenozoic Era In the Florida Panhandle, an unconformity separates the basal Paleocene sediments from the Upper Cretaceous rocks (Applin and Applin 1944, Rainwater 1960). Applin and Applin (1944) have stated that inthe Tallahassee area, Paleocene strata lie unconformablyonbedsoftheTaylorAge, withthe formations in southern Alabama, where it crops out. The stratigraphic equivalent of these three sections (the Nanafalia, Tuscahoma, and Hatchetigbee Formations) has been recognized in the Florida Panhandle as undifferentiated Wilcox. Chen (1965) treats the Wilcox Stage in northwest Florida as a formation. Navarro equivalent and upper beds of Taylor Age being present. In the outcrop belt in Alabama to the north of the study area, the Wilcox Stage has been demona. Paleocene Series. The Paleocene Series in Northwest Florida consists of clastic beds of the Midway Age. The Midway Stage has been d~vided into three units in Alabama: the Clayton, Porters Creek, and Naheola Formations. In the Florida Panhandle, these formations are undifferentiated, which led Chen (1 965) to treatthe entire staae as the strated to be unconformable with both overlying and underlying rocks. In Florida, however, no distinctive geologicevidence of unconformable relationships is recognized. The Wilcox Formation includes marine and deltaic clastic sediments. These consist of glauconitic and calcareous sandstone and greengray micaceous calcareous glauconitic and siRy Midway ~ormafion. Lithologically, the formation Shaleconsists of dark green-gray micaceous and slightly glauconitic laminated calcareous shales, with minor Using regional lithofacies maps, Chen (1965) amounts of thinbedded argillaceous and fossilifershows that the amounts of clastic sediments deous limestones and glauconitic and calcareous crease southeastward away from the Panhandle sandstones. The thickness of these sediments vartoward peninsular Florida. His maps also show the
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Panhandle Ecological Characterization Wilcox Formation to vary in thickness from less than 200 ft in the eastern Panhandle to nearly 1,000 ft southeastward. The exposed strata of the Claiborne Stage in southern Alabama have been divided into three formations which are, in ascending order, the Tallahatta Formation, the Lisbon Formation, and the Gosport Sand. In the subsurface of northwest Florida, the sediments become more calcareous and less readily differentiated into distinct formations (Toulmin 1955). As a result, the Claibome isdivided into only two formations in the western part of Panhandle Florida, the Lisbon Formation at the top and the Tallahatta Formation below. These formations are correlative in time of deposition with the Avon Park Limestone and the Lake City Limestone, respectively, in peninsular Florida. The Tallahatta Formation in northwest Florida consists of glauconitic and calcareous sandstone, green-gray glauwnitic arenaceous and calcareous shale, and glauconitic argillaceous limestone. The Lisbon Formation is commonly a glauconitic arenaceous andfossiliferous limestone with some beds of calcareous shale. The combined thickness of the Claiborne near Bay County approaches 800 ft. The literature pertaining to the Ocala Group is extensive. Summaries are contained in Vernon (1942, 1951), Cooke (1945), Puri (1957), and Puri and Vernon (1964). The Upper Eocene strata in Florida have been separated by Puri (1957) on the basis of a detailed biostratigraphic study into three formations of the Ocala Group, the Inglis, the Williston, and the Crystal River, in ascending order. In Panhandle Florida, the Ocala crops out in Jackson and Holmes Counties, which are located along the Alabama State line north of Bay County. In his study on Holmes and Washington Counties, Vernon (1942) was able to divide the Ocala into two lithologic facies. The lower facies is typically developed in southern Alabama; it bears a lower Jackson fauna, and consists of greenish-gray glauconitic sandy limestone. The upper and more typical facies is exposed in Holmes County, and is described by Vernon as a limestone that is light yellow to white, massive, porous, and often silicified. The Ocala was described in Jackson County by Moore (1955). He describes its lithology as a white to cream colored generally soft granular permeable fossiliferous pure limestone. Overlying the Ocala, Moore identifies the Bumpnose Limestone member of the Crystal River Formation (the youngest and uppermost formation of the Ocala Group). The Bumpnose ischaracterized by soft, white limestones with Lepidocyclina chapefi(a large flat foraminifera) The top of the Ocala Group dips between 10 and 15 ftlmi as it approaches Bay County from the north (Vernon 1942, Schmidt and Coe 1978). In Bay County, the Ocala is entirely a subsurface unit (Schmidt and Clark 1980). The three formations into which Puri (1957) divided the Ocala are not recognizable in Bay County. As a resun, the system devised by Vernon (1942). an upper and lower facies, is applied in Bay County. The lower facies consistsofa lightorangeto white limestonewith high porosity, both micrite and sparry calcite cement, crystal and skeletal grain types, small amounts of glauconite and sand, and abundant fossils. Dominant fossils include foraminifera, mollusks, echinoids, bryozoans, and corals. The large foraminifera are dominated by species of Lepidocyclina, Operwlinoides and Asterocyclina. The upper facies is similar, except that glauconite is rare and chert is more common. In the northern part of Bay County, thicknesses are lessthan200ft, theOcala beingover300n below sea level. lnthe southern part of BayCounty, the top of the Ocala dips to approximately 800 ft below sea level and attains a thickness of over 400 ft. The dip and thickness, therefore, increases in a nearly duesouth direction. c. Oligocene Serles. The Oligocene series consists of two formations, the Marianna Limestone and the Suwannee Limestone. Originally named by Matson and Clapp (1909), the Marianna Limestone was described as a soft, porous, light-gray to white limestone at Marianna, Jackson County, Florida. Marianna Limestone is exposed at the surtaceof the ground along a narrow, nearly east-west band through Marianna, Florida. In Holmes County, the outcrop beltturns to the north and the strike changes to northwest-southeast as it crosses the Alabama state line.
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2. Geology and Physiography From the outcrop area in Holmes and Jackson Counties, Marianna Limestone dips gently toward the gulf coast (Vernon 1942: Moore 1955: Schmidt andCoe 1978) at approximately 11 to 13Wmi. Itsdip into southern Bay County is estimated to increase slightly to perhaps 15 or 16 ftlmi. The thickness is generally uniform in Jackson, Holmes and Washington Counties, and probably increases slightly in Bay County. The name Suwannee Limestone was first used by Cooke and Mansfield (1936) to describe exposuresof a hardcrystalline yellowish limestone visible on the Suwannee River between Ellaville (Suwannee County) and White Springs (Hamilton County). Later, Vernon (1942), Cooke (1945), Moore (1955), and Reves (1961) established the formation's presence in the Florida Panhandle. The outcrop belt in the north-central Panhandle parallels that of the Marianna Limestone. Ingeneral, it can be described as a tan to buff-colored dolomitic and sometimes clayey limestone. In some areas, the Suwannee is predominately dolomitic. d. Miocene and Pliocene Serles. These series have been divided into at least 4 stages and 15 formations, ranging from the Early Miocene Tampa Stage to the Late Pliocene Miccosukee and Citronelle Formations. Puri and Vernon (1964) defined the Tampa Stage (Lower Miocene) as comprising the Chattahoochee Formation and the St. Marks Formation. They included type-locality descriptions for both formations, but did not attempt to map their areal extent. Since 1964, several publications have reported on the geology of various areas throughout the Florida Panhandle, and all have used Puri and Vernon's nomenclature. Their descriptiondescribes the St. Marks facies downdip as calcareous, and the Chattahoochee facies updip as silty. From well cuttings in Bay County, the Tampa Stage limestones can be described as a white to light gray limestone with biogenic, micritic, and crystal grain types, moderately indurated with a micrite cement; minor amounts01 quartz sand and a trace of pyrite. It often has achalky appearance and contains fossil remains of foraminifera, coral, and mollusks (Schmidt and Clarlc 1980). The thickness of the Tampa Stage in Bay County is variable. Along the northern part of the county it ranges between 50 and 100 tt thick. The top of the Tampa Stage dips from approximately sea level in the northern partof Bay Countyto nearly 500ftbelow sea level at the extreme southeastern corner of the county. The Tampa stage is entirely subsurface in Bay County. Banks and Hunter (1973) reported on post-Tampa, pre-Chipola sediments in the eastern Florida Panhandle. They called the clays, sands, and shell bedsfound in Liberty, Gadsden, Leon, and Wakulla Counties the Torreya Formation. The stratigraphic position of the Torreya was determined by the presence of Miogypsinida (a foraminiferan genus). Gardner (1926) named the Alum Bluff Group to include Chipola, Oak Grove, and Shoal River beds. Cooke (1945) then divided the Alum Bluff Group into three formations: the Hawthorn (east of the Apalachicola River), the Chipola, and the Shoal River (both west of the Apalachicola River). Puri (19531, added the Oak Grove of Gardner (1926) to Cooke's three formations and called them all facies oftheAlumBluff Stage (Middle Miocene). Later, Puri and Vernon (1964) included in the Alum Bluff Stage the Shoal River, Oak Grove, Chipola, and Hawthorn Formations and added the Pensacola Clay, Course Clastics, and Fort Preston Formations. Huddleston (1976) redefined the marine depositsof the central Florida Panhandle. He included in the Alum Bluff Group five formations: the Chipola Formation, the Oak Grove Sand, the Shoal River Formation, the Choctawhatchee Formation, and the Jackson Bluff Formation. The main mass of the Alum Bluff Group was considered by Huddleston to be restricted to the eastern margin of the Gulf Coast Basin and to the vicinity of the Chattahoochee Arch. Planktonic foraminifera were used by Huddleston to establish the time of deposition of the deposits. He reported the Chipola Formation to be Early Miocene, the Oak Grove Sand and part of the Shoal River Formation to be Middle Miocene, the Choctawhatchee Formationof Late Miocene Age, and the Jackson Bluff Formation to be Pliocene in age. The Chipola Formation was described by Puri and Vernon (1964) in the area of its type-locality as a blue-gray to yellowish-brown highly fossiliferous
PAGE 34
Panhandle Ecologlcal Characterization marl studded with molluscan shells. This marly facies only exists in the vicinity of the Chipola and Apalachicola Rivers. Further west, Cooke (1945) described twootherfacies: asandy limestone which he said is mostly subsurface, and a light-colored coarse sandy facies that contains clay. The lithology of the Chipola varies slightly throughout its extent in Bay County; however, it can be summarized as a very light orange sandy limestone, withcrystal, micriteand pelletgraintypes,fine to coarse grain size, a sparry calcite and micrite cement, with foraminifera, mollusks, coral and bryozoans. Its induration, porosity, sand content, and occasionally the presence of argillaceous malerial, are the common lithologic variables. The Chipola is distinguishable from the underlying Tampasediments inthat theTampaisgenerally a pure white limestone with relatively few fossils. The Chipola is distinguished from the BNC~ Creek again by the latter being a purer limestone. This distinction is a subtle one and often difficult to identify. The Tampa and Chipola sediments become indistinguishable from the Bruce Creek Limestone downdip. The Chipola Formation along the Washington County line appears lo strike almost eastwest and maintains a thickness of about 50 ft. The lop of the formation dips along the strike from near sea level east of the Econfina Creek to about 150 ft below sea level near East River, a dip of about 5 RI mile. Gardner (1926) reported on acomprehensive study of the molluscanfaunaof the AlumBluff Group from a numberof outcropsin the Florida Panhandle In 1965Vokessuggested, as indicatedbythe Muricinae (Mollusca: Gastropoda), that the formation might be equivalent tothe Helvetian of Europe (lower Middle Miocene). The benthic foraminifera of the Chipola Formation were described by Cushman (1920), Cushman and Ponton (1932), and Puri (1953). Puri's report also included a list of identified ostracod species. Planktonic foraminifera were described by Gibson (1967), Akers (1972). and Huddleston (1976). In addition to foraminifera, Akers (1972) discovered the presence of some Calcareous nannofossils in the Chipola material. Coral speciesfromthe Chipola were reported by Vaughan (1919) and Weisbord (1971). Finally, Bender (1371) dated coralsfromlhe Chipola using the HelU radiometric age. He placed a concordant age of 14-18 million years on ten of the samples. This would put thechipolaintheearly MiddleMioceneorlate Lower Miocene. The Bruce Creek Limestone was named by Huddleston in 1976. He included it in agroupof three formations he mapped in coastal Wakon County. The three formations, in ascending order, are the Bruce Creek Limestone, the St. Joe Limestone, and the lntracoastal Limestone. Huddleston placed these three formations in the Coastal Group, which he explained was a new name for Alum Buff equivalent carbonate units that underlie the coastal area of Walton County and vicinity. The Coastal Groupis recognized by Huddleston as far west as Niceville in Okaloosa County, and as far east as Carrabelle in Franklin County. He further states that it is not present in southern Washington County, or at Alum Bluff in Liberty CO~nty. This formation has been identified previously as a limestone facies of the Chipola Formation (Gardner 1926, Cooke and Mossom 1929). Limestonesof similar description were reported by Cooke and Mossom (1929) in southwestern Washington County in the vicinity of the Choctawhatchee River. Samples from the type outcrop on Bruce Creek in Walton County can be correlated lithologically with cuttings and cores from areas in Bay County. Only two lithologic types within the group can be recognized. The two types consist of well-consolidated white to light gray limestone, overlain by a poorly consolidated argillaceous abundantly microfossiliferous limestone. In Bay County, the Bruce Creek Limestone is a white to light yellow-gray moderately indurated granular to calcarenitic limestone. It may contain up to 20%quartzsand, withcommon minoraccessories being phosphorite, glauconite, and pyrite. In some locat~ons, sparry calcite or dolomite is present. It is commonly cemented by micrile and becomes less indurated toward the east. The Bruce Creek Limestone is dominated by macrofossils, but microfossils including planktonic and benthic foraminifera, ostracods, bryozoans, and calcareous nannofossils are also oresent.
PAGE 35
2. Geology and Physiography The BNC~ Creek Limestone is overlain in Bay It thins and rises to the north, and extends westward County by the lntracoastal Formationorthe Jackson into southern Okaloosa County. The upper palt of Bluff Formation. It is distinguished from the Intrathe lntracoastal Formation, although predominantly coastal unit by containing less sand, clay, and phosa quartz sand, can easily be distinguished from the phate. It is also much more indurated andcrystalline. Pliocene to Recent sand because it contains phosThe Bruce Creek Limestone also contrasts in color phorite, poolly consolidated limestone, and foramwith a white to light yellow-gray being easily distininifera. guished from the olive to gray green color of the lntracoastal Formation. Lastly, the BNC~ Creek Limestone is less fossiliferous than the lntracoastal Formation with its abundant fossils. In northern Bay County, the Bruce Creek Limestone is sometimes overlain by the Jackson Bluff Formation, which is much less indurated andcontains largerquantitiesof sand and clay. The Jackson Bluff Formation essentially is an olive-green shell marl, which is easily distinguished from the white, crystalline to micritic Bruce Creek Limestone. The Hawfhorne Formation exhibiis a wide range of lithotypes in the Panhandle, including shallow marine cahnates, restricted lagoonal clays, and possible prodelta elastics. Thought to be middle Miocene in age, it underlies most of the surlace outcropping sediments of the Tallahassee Red Hills inthe Panhandle. Itsinfluenceon plant sand animals is confined, therefore, to the lower slopes of ravines where it has been exposed by gully erosion. It is most common in central Florida where it was described. The Bruce Creek Limestone extends westward across southern Walton County and is thought to The 'luff Formation is found through lose its identity somewhere in Okaloosa County. To Of the central and 'Outhern pa's Of the the east, it has been idenfified in a core on St. Joe handle. Its outcrop pattern is a narrow belt extendSpit in Gulf County and in a near Dead Lake in ing from southern Washington County eastward to Calhoun County. The Bruce Creek Limestone is a the Jackson Bluff area of Leon county. From there very low-angle, wedge-shaped deposit reaching a the outcrop belt apparently turns southwest where maximum thickness along the coast of about exposures occur in the vicinity of Crawfordville in 300 ft. Planktonic foraminifera place the Bruce Wakulla (Banks and Hunter HudCreek Formation inthe Middle Miocene (Huddleston dlest0n 1976). The Jackson Bluff Formation along the lower Sediments of the Choctawhatchee Stage in the Florida Panhandle are exposed in a narrow band extending from 20 mi west of Tallahassee, Leon County, northwest to DeFuniak Springs, Walton County, a distance of about 80 mi. The exposed sediments are tan, orange-brown, or gray-green sandy clays, clayey sands, and shell marls. The outcrops generally are poorly exposed and small. True stratigraphic relationships are poorly understood (Puri and Vernon 1964, Rainwater 1964, Waller 1969, Akers 1972, Huddleston 1976). The lntracoastal Formation describes the body of sediments which was called the lntracoastal Limestone and St. Joe Limestone in Walton, Bay, Okaloosa, Calhoun, Gulf, and Franklin Counties (Huddleston 1976). The lntracoastal Formation in Bay County is a low-angle, wedge-shaped deposit up to 240 ft thickand occurring principally along the coast. Ochiockonee River consists of three clayey, sandy shell beds,differentiatedonthe basisof lithology and mollusks. In Bay County the Jackson Bluff Formation is a calcareous sandy clay to clayey sand wntaining large quantities of mollusk shells. Along the coast in the vicinity of Bay County the Jackson Bluff Formation Is underlain by the lntracoastal Formation. The limestone portions of the Jackson Bluff Formation has more mollusks and is better indurated than the lntrawastal Formation. In color, the Jackson Bluff limestones are light grays in contrast to theolive-greentobuff colorof the IntrawastalFormation (Schmidt and Clark 1980). Overlying the Jackson Bluff Formation is the Pliocene to Recent Sand Unit, which is readily distinguished from the Jackson Bluff Formation by having no limestones, very little clay, and almost no fossils. Studies of the planktonic foraminifera of the Jackson Bluff Formation place Its age as Late Pliocene (Akers 1972, Huddleston 1976).
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Panhandle Ecologlc The Miccosukee Formation is a series of silts, sands, clays, and gravels that were deposited as deltaic and fluvial sediments. It outcrops in the Tallahassee Red Hills beginning about the Ochlockonee River (eastem margin of the Panhandle as we have defined it), and is common eastward through the Northern Highlands and Central Highlands of peninsular Florida at the highest elevations. Thought to be Late Pliocene in age, it may be contemporaneous with the Cironelle Formation of the Panhandle. Most of its physical and chemical properties that affect plants and animals are the same as those of the Citronelle Formation. The Clronelle Formation iscomposedof prodeltaic, deltaic, and fluvial depositsof sands, clays, and gravels. These clastics appear to have been deposited contemporaneously with the Miccosukee Formation, but are geographically separated from it. The Citronelle deposits outcrop across the Northern Hiahlands from GadsdenCountyand Liberty County maintained in the fire-protected ravines, and accommodated by the higher humidity of ravines. e. Pleistocene to Recent. The relatively short period of the Pleistocene (2.0 million years) witnessed several drastic fluctuations in sea level. These were brought on by climate changes that caused water in the oceans of the world to accumulate in continental ice sheets and extensive montane glaciers. As the glaciers grew, ocean levels dropped to as much as 300400ft lowerthan the present sea level. Duringwarminterglacialperiodsoceanwaters rose, but Drobablv did not exceed present sea level on-the east to Escambia count; on the west. ~h& range in thicknessfromafewtensofft inthewestern Tallahassee Red Hills to hundreds of R in the Western Highlands. In the Gulf Coastal Lowlands, the Citronelle Formation thins toward the coast, and is overlain by terrace sands and other Pleistocene and Recent deposits. Clays and silts in the Citronelle Formation give soils derivedfrom it their loamy character. The water retaining capacity of these soils make them better suited for a wide range of plants, such as the rich groundcover flora of grasses and forbs in the longleaf clayhill community. These soils are more nutrient rich from inorganic mineral leachates than the pure quartz sands of sandhills. The high clay and sin content of the Citronelle Formation facilitates surface erosion by allowing excessive rainwater to runoff overthe surface of the ground. Because of this and the generally higher elevationsreachedinthe Panhandle by the Northern Highlands, landforms underlain by the Citronelle at the surface are highly gullied. The topographic relief of the Nolthern Highlands is due, primarily, to this erosion. The ravine valleys provide many of the lowervalley slopes that are naturally protectedfrom fire, allowing mesic hardwoods communities to develop on them. Many animals and plants are until the past 10,000 years (end of the Pleistocene). Evidencelromthetwo lowerterraces, thesilver Bluff (1-loft) and the Pamlico (&25 It), indicate that two stands of the sea slightly higher than present may have lasted for short periods of time before the present sea level was established only about 6,000 years ago. As a result of these post-Pleistocene fluctuations, coastal regions of the Panhandle less than about 2535 ft above sea level have experienced a complicated history of erosion, deposition, and reworkingof sedimentsfromthe actionof rainfall, wind, and waves. Dunes, bars, spits, beach ridges, and other coastal features were stranded inland as sea level receded. Some of these are delineatedon the physiographic map of the Panhandle (Figure 5). The consequences of sea level fluctuations during the Pleistocene had tittle effect upon the present exposed land surfaces of the Panhandle above the two terraces just mentioned. This is because once the ocean withdrew from the higher terraces it never returned. The surface of the Panhandle above the Pamlico terrace was exposed to erosion and colonization by plants and animals just as this area is today. Pleistocene sea level fluctuations had their greatest effects, however, on the lands that today are submerged under the ocean. During lowered levels of the ocean surface much of the present sea floor was exposed to the air and to colonization by terrestrial plants and animals. During the Pleistocene the acreage of the Panhandle increased by a factor of 1 112 to 2 times by newly emerged Continental Shelf that was annexed to the present coastline.
PAGE 37
Figure 5. Physiography of the Florida Panhandle (after Puri and Vernon 1964, Brooks 1981b).
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Panhandle Ecologlc :al Charactorlullon The present-day coastline is marked by beach ridges, barrier islands, spits, lagoons, estuaries, wave-cut cliffs, dunes, swales, sloughs, flats, and other topographic features created by Recent coastal processes. Beach ridges are marine in origin, formed by wave swash, which pushes sand up high as a berm adjacent to an existing beach, effectively moving the beach to the seaward side of the new sand berm, or beach ridge. This oiten happens during certain types of storms. Beach ridges usually occur side by side, as on St. Vincent Island. Dunes are of wind-blown origin and may assume any shape or orientation. Drifting sand grains become rounded and their surfaces are scratched or frosted from abrasion by other sand grains. Dunes can build up 30 ft or more on top of the beach ridges they usually are perched on. Sand left on the beach by wave swash dries out during high tide and is subject to being moved up the dune face by the proper winds. Two adjacent barrier islands of the present coastline exemplify the complicated interactions of wind, wave, sand supply, and offshore currents. St. George Island has Increasingly large windcreateddunesgoingeasttowest. Immediatelywest, however, St. Vincent lsland is entirely composed of relatively low elevation, wave-created berms aligned in parallel sets. Shell fragments are less common on dunes than on beach ridges because they are less amenable to transport by wind than by water. The size of the grains, the lack of a carbonate adhesive leached from shells, and the rounded surface of grains allows dunes to be eroded or reworked more easily than beach ridges. Furthermore, the water holding capacity of dunes is much less than that of beach ridges, and dunes provide severely xeric soils for plants. This is true of the actively forming dunes along the present coastline as well as the ancient dunesanddunefields strandedfar inlandatthe edge of ancient stands of the sea. Barrier islands that have formed in the past 6,000 yearsor so arecommon along the coast of the Panhandle. These generally are parallel to the coast andconsist of seriesof beach ridges.dunes,swales, interdune flats, and sloughs. East to west, these are Dog, St. George, St. Vincent, and Santa Rosa Islands. Barrier spits form in similar fashion to barrier islands, but are connected to the mainland at one of their ends. East to west, they are Alligator Spit, Indian Peninsula, St. Joseph Spit, Crooked Island, Shell Island (once a spit, broken by dredging), and Perdido Key. A lagoon is the brackish water bay (also called an estuary) between barrier islands or spits, and the mainland. Panhandle Florida is abundantly endowed with brackish water lagoons, providing important habitat for sea birds and ocean fisheries. Big Lagoon, Santa Rosa Sound, St. Andrew Sound, and St. George Sound are among the largest of these. The plants and animals of Panhandle Florida havecontactwith and are influenced by the soils they are rooted in, or live on, or burrow into. Most of the soils of the Panhandle are of Pleistocene to Recent age, and are presently actively being formed, reworked, and reformed by the action of rainwater. Only on hardrock limestone outcrops such as those along the Chipola, Apalachicola, Ochlockonee, Sopchoppy Rivers or at various other places such as Falling Waters State Park do older sediments directly influence animals and plants as a physical substrate. Sediments older than the Pleistocene also are exposed on ridge slopes and hogbacks of the Northern Highlandsthat areunder active gullying (so that the parent Miccosukee or Citronelle Formations are exposed). On the surface of lower slopes, andespecially inthebottoms of streams, rivers, flats, anddepressions, the sediments areof Recent origin. Pleistocene and Recent sands and organic deposits are the main surface sediments of the Panhandle south of Cody Scarp. These occur in thicknesses of a few inches to dozens of feet. They are residual, leached, and reworked sediments from older deposits. 2.4 Physiography 2.4.1 The Nonhern Highlands The Northem Highlands (Figure 5) extend across the Panhandle from the big bend region on the east to Alabama on the west. To the north, they extend into Georgia and Alabama along the entire length of the noflhern boundary of Florida. The almost continuous highland is parted by the larger stream valleys, several of which form a large low areacalled the Marianna Lowlands (see below). The
PAGE 39
2. Geology and Physiography marginal slopes of the Northern Highlands are well formed in an ancient, abandoned bed of the drained by dendriiic streams but the tops are gently Apalachicola River. The HolmesValley Escarpment sloping plateaus. borders the northern edge of New Hope Ridge, and holdspromise for interesting biological exploration in The Northern Highlands are limited On the South the future. ~odh facing slopes in the Panhandle by the Cody Scarp which extends regionally through often harbor northern relicts, the East Gul and Atlantic Coastal Plains (Doering 1960). This outfacing scarp is the most persistent The high remnant hills of Washington County topographic break in the State. Its continuity is Orange, Rock, High, Oak, and Falling Water unbroken except by thevalleysof maiorstreams, but indicate that the Northern Highlands were once its definition is variable. In many places, it can be ,,tinuous and that the western t+ighlands, New delineatedwithunequivocalsharpness;inothersitis H~~~ id^^, Grand id^^, and Tallahassee Red shown Only by a gradual reduction of average Hills were connected. elevation, and a general flattening of terrain as the lower elevations are reached (Puri and Vernon The Tallahassee Red Hills are a heterogeneous 1964). mix of rolling topography that sweeps southlrom the Georgia State line to Cody Scarp, and runsfrom the The significant subdivisions of the Northern Apalachicola River on the west to the Suwannee Highlands include the Western Highlands, Grand River basin on the east, We have defined the Ridge. New Hope Ridge, Washington County outlieastern margin of the panhandle as lying along the ers (Knox Hill), and the Tallahassee Red Hills (Figbed of the Ochlockonee River because a strong ure 5). change occurs here in the underlying geology and The Western Highlands is a beR of high, rolling surface physiography. East of the Och~ockonee hills that stretch between Escambia County on the River, the Tallahassee Red Hills lie in the Florida Big west and Holrnes and Walton Counties on the east. and the surface Of the landform there is The soils are derived undi,,erentiatedsands dominated by subsurface limestone solution. Large, sandsofthe Ciironelle Formation, provid. solution subsidence basins dot the landscape and ing dry conditions on the upland slopes and ridge contain large lakes such as Lakes Jackson, lamonia, crests, Downslope it is common to find seepage Miccosukee, and Lafayette, and a host of smaller water emerging from gentle slopes, resuning in lakes and swamps. West of the Ochlockonee River, wetland hillside seepage bogs inthe Panhandle, the rolling relief of theTallahassee (Clewell 1971, Wharton et al. 1976, Means and Red Hills is caused primarily by surface runoff. The Moler 1979). At the end of the Western terrain in this area is more relieved than any other Highlands in Holmes and Walton Counties, low, wet area in Florida because of short tributaries incising karst depressions resulting from solution subsithe hills. In addition to the the deep stream valleys, dence of the underlying limestones are orravines, there are high (>200ft) bluffs overlooking common. From Okaloosa county westward, howthe *palachicola River On the east. ever, subsurface solution activity is not recognizable. The highest elevations in Florida occur in the 2'4'2 The Marianna Lowlands Western Highlands southeast of the border town of The Marianna Lowlands in HOlmeS, WashingFlorala, Alabama, north of Walton County. ton, and Jackson Counties cover a rectangular area of approximately 30 x 64 miand extend into Alabama Grand Ridge and New Hope Ridge (Figure 5) and Georgia along the principal streams. They are are two fragments of the Northern Highlands that bounded on the west by the Western Highlands, on have been isolated between the Western Highlands the southeast by Grand Ridge, and on the south by and the Tallahassee Red Hills by the ChoctawNew Hope Ridge. Because of the abandoned valhatchee, Chipola, and Apalachicola river valleys. leys and stranded alluvial deposits, it is believed that Grand Ridge has little that is distinctive biologically, Marianna Lowlandswere generally developed along but it does wntainocheesee Pond,oneof the larger the valleys of the Apalachicola, Chattahoochee, lakes of the Panhandle and a remnant wetland Chipola and Choctawhatchee Rivers. 17
PAGE 40
Panhandle Ecologlt :a1 Characterlzatlon The land surface is well drained and has a well developed dendritic stream pattern. It is pocked by sinks interspersed with rolling hills and abrupt ridges. The ridges are bounded by stream channels or by sink rims. Broad, shallow basins are generally present, some filled by water. The Marianna Lowlands possess Florida's most extensive system of air-filled cavern passageways, and the only ones in the Panhandle. The calcium-rich soils that develop on top of the limestone are often moist and rich in nutrients. 2.4.3 The Gulf Coastal Lowlands The Gulf Coastal Lowlands physiographic region extends inland to its contact with the Norfhern Highlands along Cody Scarp (Figure 5). It is continuousfromsouthern EscambiaCounty onthe westto Wakulla and southern Leon Counties on the east. The Gull Coastal Lowlands are generally low in elevation and poorly drained on the east, but rise to form a high, sandy, well-drained plateau whose southern margin is a wave-cut escarpment west of Walton County. Coastal terraces characterize many of the landforms of the Gul Coastal Lowlands and their low scarps form the boundaries between them. The Gulf Coastal Lowlands are at least as diversephysiographically and biologically from west to east as arethe Northern Highlands. Puri and Vernon (1964) listed nine subdivisions and there may be more. Immediately adjacent to the coast, the Gulf Coastal Lowlands are composed of barrier islands, lagoons, estuaries, coastal ridges, sand dune ridges, and relict spits and bars, with intervening coast-parallel valleys. Inland, northern Bay, southern Washington, and western Calhoun Counties have well developed karst ponds and lakes. Greenhead Slope isa massive sand deposit that is pocked by circular depressions and round lakes. Aside from the limestone-dominated Marianna Lowlands, Greenhead Slope is the only other land area of the Panhandle exhibiting extensive karst features. It possesses a few steepheads, some draining into Econfina Creek and others into karst depressions. Beacon Slope east of the Apalachicola River has more steepheadsdeveloped in it than any other part of the Panhandle, although by sheer volume of flow some on Eglin Air Force Base are larger. Because Beacon Slope is immediately adjacent to and belowthewelldeveloped Apalachicola ravines inthe Tallahassee Red Hills, the steephead ravines of Beacon Slope support most of the same endemic and relict specles that are found just north. Beacon Slope, Fountain Slope, Greenhead Slope, and the massive sand deposit in southern Santa Rosa, Okaloosa, and Walton Counties may all be ancient coastal sand deposits formed contemporaneously during the Pliocene when the sea stood near Cody Scarp. Today they are stranded inland by lower sea level, but it is significant that each feature contains numerous steepheads and endemic plants and animals that may have evolved on each feature during the long period when each was part of a developing barrier island-lagoon set. Relict bars and spits are common In Gult, Liberty, and Franklin Counties. In fact, ancient bird'sfoot deltas can be traced on the land surface on both sides of the IowerApalachicola River. Moreover, this part of the Gulf Coastal Lowlands is biologically so distinctive that it probably deserves its own physiographic rank. At least 15 races and species, and one genus of plants and animals have their distributions centered on the lower Apalachicola valley (Means 1977). Many unique, silt-bottomed savannas and cypresswetlands occur here, andthe region beckons for further exploration. 2.5 Regional Marine Geology Two regional geologic features control the coastal configuration of the Florida Panhandle: the ApalachicolaorSouthwest Georgiaembayment and thechattahoochee arch (Figured) (Schnable 1966). The Apalachicola embayment is a shallow basin (syncline) situated between the Ocala and Chattahoochee uplifts It is located where the east-west strike of the coastal element changes to approximately north-south in southwestern Georgia and norlhern Florida (Murray 1961). The Apalachicola dela lies near the center of the embayment. The thicknessof the Pielstocene and Miocenesediments in the eastern porlionof the area reflectthe influence of the Ocala uplift as a structural high (Schnable and Goodea 1968).
PAGE 41
4. Geology and The thickness of the tertiary sediments in the northeasternGuKof Mexico issubstantially lessthan those of the northwestern and nonh central gulf (Vause 1959). This is probably a result of the Apalachicoladelta region lying furtherfrom the main axisofthe Gulf Coast Geosynclinethan mostcoastal areas to the west and as a result being more stable and structurally less complex (Schnable 1966). Pleistocene to Recent sediment thicknesses along the present coast vary from less than 3 m in the easternmost portion of the Panhandle to 36 m in the westernmost part (Figure 6) (Schnable 1966). Several investigators have examined the offshore sediments in the region (Lapinski 1957, Milton 1958, Chen 1978). West of Ochlockonee Bay. the Apalachicola and Ochlockonee Rivers supply alluvium downdrift for a system of barrier islands (Dog Island, St. George Island, and St. Vincent Island), beaches, spits, and bars. The Ochlockonee and Apalachicola are the eastem most rivers carrying appreciable amounts of detrital and mineral matterto the gulf. The region from the western end of St. George lsland to the Ochlockonee Bay is classified as alow-energy area(Figure7) (Tanner1960b). The sediment from alluvial and shelf sources is mostly lost to coastal deposition west of St. Joseph Bay where the 25-m depth contour approaches the nearshore region and funnels material from the westward drift out into deeper water (Stout 1984). Further west, Santa Rosa lsland receives sediment downdrift from Choctawhatchee Bay and sands from the Continental Shelf (Kwan 1969). Most of the fine-grained sediment carried by the Apalachicola and Ochlockonee Rivers is contained within the estuaries (Kofoed and Gorsline 1963). Kofoed (1961) and Schnable and Goodell (1968) concluded that no significant quartz sand was being supplied tothe littoraldrift systemoutsidethe barrierislandchain. They contendedthat the "largevolume of sand composing the barrier islands and offshore shoals can have been supplied only during lower sea-level stands." There has been extensive beach erosion on the spits and barrier islands in recent time in this area of supposed excess sediment (Wamke 1967). Clearevidence for erosion are tree stumps in the water on the beaches near East Point in the Apalachicola system and on St. George Island. The littoral drift, or longshore sand transport, along the Panhandle coast has been described by Tanner (1964), Bruno (1971), and Waiton (1976). Figure 8 gives a view of littoral drift along a portion of the Panhandle from Cape San Blas in Gulf County to the western border of Okaloosa County. From the western end of the Panhandle toward Bay County, the shoreline becomes concave. This natural concavity is broken by St. Joseph Bay. The area from Panama City west to East Pass is presently undergoing erosion. In recent geologictimesthisareamay have been a source of sand for areas to the west fWalton 1976). In contrast. the shoreline from East bass (St. ~ndrew Bay system, Bay County) to Perdido Pass may have been an area of accretion (Santa Rosa lsland is evidence) in recent geologic times, though Santa Rosa lsland is now in a state of equilibrium. There are no true barrier islands present in the region west of St. Joseph Bay to Destin (Tanner 1960b). Moderate-energy wavesform the gun front beaches. From Panama City Beach to Destin the shoreline is a mainland beach (Gorsline 1966). For approximately 85 km the beach is unbroken, with only small streams interrupting the continuity. Associated with the larger streams are small brackishwater bays. A wide recent beach abuts a prominent bluff &I0 m high. The present coast is relatively stable. From Choctawhatchee Bay Pass westward to the Alabama border, a series of narrow barrier islands border the mainland. Santa Rosa lsland is nearly 81 km long and is not more than 0.7 km wide. It represents the largest unbroken stretch of beach in the eastern Gulf (Brooks 1973). The beach is composed of pure white quartz sand (median diameter approximately 0 25 mrn). During heavy stormsthere is local washover across the island. There is extensive dune development on the eastern fifth of the island Near the western end of the island salt marsh peat is exposed on the foreshore. The foreshore slope is relatively steep (approximately 9'-10') so that the 15-m depth contour comes within 0.6-0.8 kmof the shoreline. Because of this steep ramp, the area has recorded some of the highest waves in the northeast Gulf of Mexico (Gorsline 1966. Brooks 1973).
PAGE 42
r U m Choctawhatchee Bay, Flgure 6. The thickness of Eocene to Recent sediments along the Panhandle coast from Choctawhatchee Bay to the AlabamaFlorida border (after Marsh 1966).
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4. Geology and Physiography ALABAMA GEORGIA GULF OF MEXICO Diurnal Tides (ft) (moderate energy) Figure 7. Coastal energy levels and tidal ranges for the northeastern Gulf of Mexico (after Stout 1984). -.. \ -ALABAMA GEORGIA a wErrr4ao wr oa1.r ~~SlWIRDOFl SOUTHEASTWARDI NET DRIFT 0 10 20 30 40 50 GULF OF MEXICO Figure 8. Schematic of net littoral drift along "idealized" Panhandle coast (after Walton 1976). Q, shows magnitude of littoral drift in cubic ydsiyr.
PAGE 44
Panhandle Ecologlcal Characterization The northeastern Gulf of Mexico is not as tectonically active as areas to the west. The Apalachicola delta region has been a relatively stable area since at least Pamlico (Sangamon -the last glacial recession) time (Schnable 1966). There are two prominent offshore morphological features present in the eastern portion of the Panhandle region: the two large shoal areas off Cape San BlasICape St. George (Stauble 1971) and the submarine sand bodies in the nearshore gulf off Choctawhatchee Bay (Figure 9; Hyne and Goodell 1967). The two broad shoals extend nearly 16 km into the gulf and are characterized by a series of broad ridges and troughs. Mean grain size of the quartz sand increases seaward from the beach and therefore the sand in these shoals is coarser than the sand now being transported by the longshore drift system (Schnable 1966). The present energy levels along this coast are not sufficient to redistribute or remove sand from the shoal areas or sand bodies (Tanner 1961,1964; Tanner et al. 1961). The outer shoals have remained relatively unchanged for over a century (Schnable 1966). The sands in these offshore areas are relict and were probably originally deposited at some early low stand of sea level. Several mechanisms have been proposed to explain the origin of the shoals. One is a storm-surge ubmarine Topography contour interval 10 feet Figure 9. Nearshore bottom topography off Choctawhatchee Bay showing sand body features (after Hyne and Goodell 1967).
PAGE 45
4. Geology and Physiography phenomenon that formed the ridge and trough configuration (Tanner 1960a). Others have proposed that the shoals are drowned barriers, although the sand has been extensively reworked. In addition, the ridges of the shoals contain concentrations of heavy minerals that may indicate a dune origin (Schnable 1966). An interesting discovery has been made in the offshore waters south of Panama City Beach. Remnants of an ancient forest are present at a depth of approximately 18 m directly south of the beach and in 6 to 15 m of water nearer the St. Andrew Bay entrance (Lawrence 1974, Burgess 1977, Salsman and Ciesluk 1978). The latter site is located beneath sediments comprising the present-day barrier island complex. The wood dates from 27,OO to 36,500 years old and is believed to be part of a large forest that covered the area during a lower sea level stand. The forest extends many kilometers south of the present shoreline. The wood is mostly pine but contains small amounts of hardwoods such as oak, beech, hickory, and elm. This suggests the vegetation was very similar to present-day stands 32-48 km north of Panama City. The submerged forest A Cape San Blas Apalachicola further supports the contention that the present-day beaches and islands are recent geologic features. 2.6 Local Marine Geology' The following section is a discussion of the origin and geological aspects of the major bay systems included in the Panhandle region. 2.6.1 Ochlockonee Bay The Ochlockonee Bay represents a drowned river valley that was cut during lower stands of sea level in the Pleistocene. Bottom topography at the mouth of the bay resembles a drowned delta with two linear shoals on each side of the channel that may represent an old river channel with natural levees on each side. The "old" Ochlockonee River probably had several routes to the gulf during the late Pleistocene (Schnable 1966). The stratigraphy of the nearby region is unique in the Panhandle. The Miocene is very close to the surface at the present coastline in the vicinity of Turkey Point-St. Teresa (Figure 10). From there the B Carrabelle St.Teresa 40 80 2 I 4 al PLEISTOCENE Upper Sequence 120 0, al al C PLEISTOCENE Lower Sequence r -\\\\\' .,. \\\\\\\ El MIOCENE Choctawhatchee 160 !? MIOCENE -Chipola? Figure 10. Stratigraphy of coastal region from Cape San blast^ Ochlockonee Bay in the eastern Panhandle (after Schnable 1966).
PAGE 46
Panhandle Ewloglcal Characterlzatlon surface dips to the southwest and the PleistoceneMiocene contact is approximately 45 m below the ocean floor off Cape San Blas. 2.6.2 ~palachlcola Bay During the Cretaceous period, the present Apalachicola River system was submerged under ancient seas (Tanner 1983). The origin of the present Apalachiwla River probably occurred some time during the Miocene epoch (Livingston 1984). The present structure of the bay is nearly 10,000 years old (Tanner 1983). The present barrier island chain formation began approximately 5,000 years ago when sea level reached its modern position. It was at this time that the general configuration of the bay was determined, except for the southward migration of the delta flat (Tanner 1983). 2.6.3 St. Joseph Bay Stewart and Gorsline (1962) described the following sequence of events leading to the format~on of modern St. Joseph Bay: (1) Following the last rise of sea level (approximately 5,000 years ago), a series of north-south trending beach ridges was formed and an open coast profile was established offshore. An even older set of ridges was submerged and subjected to marine degradation, resulting in the formation of a shoal trending south-southwest from the mainland through the Cape San Blas area. (2) A large distributary of the Apalachicola River, its course controlled by beach ridge development, emerged about 8 km north of the present bay and deposited a wedge of fine-grained material overthe terrace sediment. At approximately the same time, gyral currents established by the presence of the southern shoal initiated spit growth from the east. (3) Rapid spit development segregated a large portion of the older surface and prevented substantial filling of the bypassed area. At th~s time, the detrital supply from the distributary had ceased and sand supplied by longshoredrift and biologiccarbonate formed the major contribution. of the past lagoon, sand encroachment has been slow and limited, and a large portion of the older surface remains relatively unobscured. Present-day sedimentation in the bay comes from 2 dominant sources: the coastal transport of clean quarlz sand from the east and biological activity withinthe area itself. In theabsence of a substantial amount of silt-size quartz particles, carbonate tests and shell fragments increase in importance as the applied energy of the environment decreases southward in the lagoon. Residual gravels and sands dominate a sizeable portion of the southern Slope of the bay that is removed from active deposition of detrital material (Figure 11). Since the formation of the enclosing spit, a reduced rate of deposition has preserved the bottom contour in the central portion of the lagoon. The depth and gradient closely approximate that of the offshore slope (Stewart and Gorsline 1962). There is a far larger accumulation of clay in the central bay basin than can be accounted for by present minor sources This has led to the conclusion that these fine sediments represent a relict surface produced by the discharge of an old distributaly of the Apalachicola River. The sediments of the area are typical of those from a Coastal Plain source. Small differences can be attributed to attrition and loss in transport. Less than 1% of the typical east gulf "kyanite-staurolite" suite of heavy minerals is present. Kaolinite, montmorillonite, and illinite are the clay minerals present, with kaolinite dominating. 2.6.4 St. Andrew Bay System The St. Andrew Bay system is a typical tidal embayment. It appears that it was formed during the last malor rlse in sea level (the Holocene transgression) thattook placeapproximately 5,000 years ago. As sea level rose and flooded the valley of a local river system, ocean waves and longshore currents built up a barrier baracross the mouthof the resulting bay. (4) Development of stronger tidal currents in recent times controlled spit growth and furnished a Uniform sediment ridges on the bottom of St. mechanism for the transport of sand into the basins. Andrew Bay were documented by Salsman et al. Sand has wmpletelycoveredthefine-grained mate(1966). The ridges, composed of a fine sand were rial tothe north. Under the lower energy conditions asymmetric, with steep slopes, 30 to 60 cm' high,
PAGE 47
4. Geology and Physiography //.'//I' GULF OF MEXICO //////////// /////////// ////
PAGE 48
Panhandle Ecological Characterization facing down current, and had 13 to 20 m wavethe formation of Choctawhatchee Bay lengths. The predominant flood tide caused them to migrate northeastward at an average rate of 1.35 cm per day. The migration rate was very sensitive to changes in current speed. Near the leading edge of the ridge zone, where sand transportwas primarily of bed-load mode, each ridge passing a point left behind an average 12 cm-thick sand layer. (1) A sharp rise in sea level (7,000 to 20,000 years ago) inundated the Pleistocene River valleys, from the coastal embayments that are presently the bayous on the north side of the bay. Between 3,000 and 7,000 years ago, when the rate of sea-level rise slowed, the westward longshore drift system began to form Moreno Point.the eventual barriers~it. It was HOlmes and Goodell (1984) have reported on not until sometime arier3.000 yearsago that y ore no the sediments in St. Andrew Bay. Point effectively closed off the bay. (2) Isolation from the Gulf of Mexico had a pro2.6.5 Choctawhatchee Bay System found effect upon the sedimentary environment The region presently covered by the Choctawwithin the bay, producing modifications in three fachatchee Bay was as much as 92 above sea level tOrS that caused the sediments to undergo rad~cal the Pleistocene epoch (Puri and Vernon alteration. Biologically, the present environment 1964) and became gradually inundated by oceanic lacks the prolific shell-producing organisms of the in more recent times, As the Gulf of Mexico Past. Physically, the entrapment of fine material ~~~c~f~r~~~~~~~~~~' ~~~~~~~~~~~ ~~~$~ ~~t~d~~'~t?~~~~e~~~~~~~n~~~~ ;;J; ~;t;;~O~;;~;;~et;;;;p;et;m~;;I ~~s~~~~~o~~~i~{ 2 ,",y';iC~,","~~;ti~~ merit now known as Old Lagoon Pass, At times causedmodifications inthephysiochemicalenvironbefore the formation and stabilization of East Pass, merit, as reflected in the low alkalinity and highly Choctawhatchee Bay became a freshwater lake reducing character of the surface sediments of the when periodic shoaling closed the natural pass, bay' The land immediately adjacent to the bay is Minor fluctuations in sea level within historical 1964), Moreno Point is part of a massive sand ridge mately 0.5 m under water) next to emergent marsh ~~~~~~~~~~~o~~.~~~~~~~y2 :h: ?E~~Y~tL~e?a~~~~~tG~~~k~~~E~~l~~~~k narrow and Rocky bayous in the south Shoreline of the bay. This change in water corner of the bay have very steep shores, with sharp level Of the bay "lay be in par' general slopes extending down to depths of more than m, coastal subsidence determined by Marmer (1952) Thiscontrasts with the eastern end, which is marshy Irom tidal due to poor drainage, and the western end, which is composed of residual sand. Both of these ends are relatively shallow, wlth low gradient slopes. The bedrock limestone underlying Choctawhatchee Bay is found at a depth of approximately 45 m (Tanner 1964). The recent sediments of the bay are described by various authors (e.g., Postula 1967, Palacas et aL 1968,1972). Goldsmith (1966) reported a large contrast in condition between the present sedimentary environment andthe one previously occupying thearea. He reported the following sequence of events leading to Of historical note, farmers originally dug a ditch across Santa Rosa Island that eventually became the main Destin channel and resulted in major changes in the depositional and erosional patterns within the bay. The channel has since been maintained by the U.S. Army Corps of Engineers. 2.6.6 Pensacola Bay System The recent sedimentology of the Pensacola Bay system is a result of watershed erosion since the Pleistocene epoch (Olinger et al. 1975). During the Pleistocene, Citronelle deposits were reworked and
PAGE 49
4. Geology and Physiography intermixed with marine terrace sediments (Marsh 1966). These deposits are presently eroding. Present-day sediments consist primarily of unconsolidated sand, silts, and clays of the Coast Plain Province that were deposited before the last sea-level rise. This layer is underlain by a veneer of Pleistocene terrace deposits that overlie tertiary beds of sand, silt, and limestone (Figure 12). The Citronelle Formation, the only formation with marine outcrops in the region is composed of layers of sand, gravel. iron-cemented sandstone, fossil woods, and kaolinite (Marsh 1966). H~~ath (1968) described the recent sedimentology of the Pensacola Bay system: (1) Sediments enter into the system from two sources: stream discharge from the surrounding land, and wave and current action that bring them into the bay from the Gulf. (2) The Escambia Riverdischarges morecoarse material into the bay than do the other rivers. coarser mean grain size and lower average silt-clay content. Most of its sediments were probably derived from offshore sources and are not of fluvlal origin. 2.7 Offshore (Outer Continental Shelf) Oil and Gas Reserves Recently, the development of the Outer Continental Shelf (OCS) oil and gas resources has been a major concern of coastal Panhandle residents. At present, three offshore lease areas lie off the imrnediate Panhandle coast (Figure 13): (1) the Pensacola area; (2) the Destin Dome area, and; (3) the Desoto Canyon area. Since the early 1970's, various oil companies have maintained exploratory interest in these lease areas. The Destin Anticline and the southwest corner of the Pensacola area are believed the most promising as hydrocarbon-producing areas (Figure (3) sediment distribution reflectsthe bay'scircu. 13). Eighteen exploratory wells have been drilled lation consisting of strong north-flowing within the Destin Dome area in the Smackover currents along the eastern shores and south-flowing geological formation, as of the summer of 1985. The rllrrontc noar the WP+~O~ roact~ depthstowhich thewellsweredrilled, 5185-5795 m, -. -. . . . . . . . .. indicate natural gas may be a more likely yield than (4) Sand-size sediment predominates with siltoil. ~h~~ far, the natural gas discovered in the clay being the second most abundant. Smackover Formation in other regions has con(5) Grain size increases in every direction away tained hydrogen sulfide (said to be "sour") that is from the bav center. corrosive and must be subjected to more costly (6) The main mineral constituents are quartz, processing than higher quality gas. Offshore oil kaolinite, montmorillonite, and calcite. activities have the potential for many harmful impacts to the nearshore coastal habitats. Some of (7) The Santa Rosa Sound is different from the these are discussed in the chaptersdealing with the three bays in the Pensacola Bay system, with a individual estuarine and marine habitats
PAGE 50
Panhandle Ecological Characterization GENERALIZED GEOLOGIC COLUMN OF FORMATIONS IN THE WESTERN FLORIDA PANHANDLE SERIES FORMATION PLEISTOCENE MARINE TERRACE DEPOSITS: Sand, light tan, fine to coarse .,. ,. . 3. ,-' h .. . CITRONELLE FORMATION: Sand with lenses of clay and gravel. -. .' .. . . ---& Sand, light-yellowish-brown to reddish-brown, very fine . -?\ to very coarse and poorly sorted. Hardpan layers in PLEISTOCENE (?) . :. . .:. . upper part. Logs and carbonaceous zones present in places. Fossils extremely scarce except near the coast where shell beds may be the marine equivalent of the fluvial facies of the Citronelle. very Eine to very coarse and poorly sorted. ~ossils abundant, mostly minute mollusks. Contains a few zones of carbonaceous material. Lower part of coarse clastics UPPER MIOCENE present only in northern part of area, interfingering with Pensacola Clay in the central part. PENSACOLA CLAY: Formation consists of an Llpper Member and Lower Member of dark-to-light-gray, tough, sand? clay; separated by the Escambia Sand Member of gra?, fine to coarse, quartz sand. Contains carbonized plant fragments, and abundant mollusks and foraminifers. Pensacola Clay is present only in southern half of area, interfingering with the Miocene coarse LIPPER MIDDLE TO clastics iii the central part. LOWER UPPER MIOCENE LISBON EQllTVALENT: Shalv limestone, dark-gray to grayish.cream; hard, compact; gla~~conitic; with thick intervals of dense, light-gray shale. MIDDLE EOCENE HATCHETI(;REE FORMATION: Clav, gray to dark-gray, micaceous, LOWER EOCEW siltv, with beds of glauconitic shale, siltstone, and limestone. I.lollusks, foraminifers, corals, echindds. Bashi Marl Member (about 10 feet thick) at base. Figure 12. Generalized geologlc column of formations in the western portions of the Florida Panhandle (after Marsh 1966).
PAGE 51
4. Geology and Physiography m [7 Proposed Tracts for Leasing Sale No 69 Expired or Relinquished Leases Kl Active Leases Destin Dome Block Figure 13. OCS leases in the Pensacola and Destin Dome Blocks offshore from west Florida (Lynch and Risotto 1985).
PAGE 52
Chapter 3. CLIMATE 3.1 Introduction The Florida Panhandle experiences a mild, subtropical climate as a result of its latitude (3O031 O N) and the stabilizing effect of the adjacent Gulf of Mexico (Bradley 1972). The waters of the gulf moderate winter cold fronts by acting as a heat source and minimize summer temperatures by producing cooling sea breezes. This gulf influence is strongest near the coast, weakening inland. Fairly detailed long-term climatological summaries are available for Apalachicola and Tallahassee. Though Tallahassee lies a few miles outside the eastern boundary of what we call the Panhandle, it is the location of much data collection and will be used to provide a more comprehensive report. More limited data are also available for Pensacola and certain other Panhandle locations (Jordan 1973). The locations of NOAA climatological stations are shown in Figure 14. 3.2 Climatological Features 3.2.1 Temperature The annual average of the mean daily temperature is in the upper 60's Fahrenheit with mean summer temperatures in the low 80's and mean winter temperatures in the low 50's. Annual and seasonal temperatures vary greatly (Figures 15 and 16) with summer highs generally in the low to mid 90's with occurrences of 100 OF or higher infrequent. The summer heat is tempered by sea breezes along the coast and up to 50 km inland, as well as by the ALABAMA GULF OF MEXICO Daily Recording 0 Daily Nonrecording I Jackson (C GEORGIA Calhoun Liberty Gadsden Wakulla yq A, 'J _..IFlgure 14. NOAA climatological station site 30 s in the Florida Panhandle (after Wagner et al. 1984).
PAGE 53
3. Climate 93 ALABAMA 93 Figure 15. Isotherms for mean maximum and mean minimum July temperatures in the Florida Panhandle (after Fernald 1981).
PAGE 54
Pan handle Ecological Characterization I a70 1260 850 8 4O I -I 1 I 61 ALABAMA I I Mean maximum temperature-January I 37 ALABAMA I Mean minimum temperature-January Figure 16. Isotherms for mean maximum and mean minimum January temperatures in the Florida Panhandle (after Fernald 1981).
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3. Climate cooling effect of frequent afternoon t hundershowers. Thundershowers occur on approximately half of the days during summer and frequently cause 10 to 20 degree drops in temperature (Bradley 1972). Winter temperatures are quite variable due to the frequent passage of cold fronts. The colder of these fronts are of Arctic origin and may bring minimum temperatures ranging from 15 to 20 OF with single-digit lows some years. Temperatures rarely remain below freezing during the day and the cold fronts generally last only 2-3 days. Temperatures in the 60's OF and sometimes 70's OF often separate the cold f fonts. This weather pattern results in average low temperatures in the mid 40's OF during the coldest months (mid-January through mid-March). 3.2.2 Rainfall The Florida Panhandle has two peak rainfall periods: a primary one during summer (JuneAugust) and a secondary one during late winter through early spring (February-April). Additionally, there are two periods of low rainfall: a pronounced one during October-November and a lesser one in ApriCMay (Figure 17). Average annual rainfall across the Panhandle is near 152 cm, varying from approximately 163 cm at the west end to about 142 cm at the east end (Figure 18). The dearth of gauging stations in some Panhandle regions may Pensacola (1 923-1 980) Tallahassee (1 885-1 980) Figure 17. Seasonal rainfall variation at selected sites in Florida Panhandle (data from U.S. Dept. Commerce 1980a,b,c). affect the accuracy of the isopleth placements in these figures. The annual rainfall varies widely (Figure 19), and the maximum recorded amount has ranged from 73 cm at Pensacola in 1954 to 284 cm at Wewahitchka in 1966 (Wagner et al. 1984). During rainy years the maximum rainfall tends to occur near the coast; however, during dry years the rainfall maximum occurs farther inland. Rainfall patterns tend to be more consistent approximately 25-95 km inland (Jordan 1984). Rainfall gradients are quite strong along some portions of the gulf coast; annual totals are as much as 12-25 cm less at stationsvery nearthe coastline than at those afew kilometers inland (Jordan 1 973). Studies of the distribution of summer rainfall, based on weather radar observations at Apalachicola and with the results supported by corresponding studies at Tampa, showed that showers within 160 km of the radar installation were nearly as frequent over the sea as over the land when averaged over a 24-hour period (Smith 1970). This and similar studies in south Florida (Frank et al. 1967) found high numbers of showers over land in the afternoon and low numbers in the early morning. They found a minimum number over the sea in the afternoon and a maximum during late night and early morning, especially within 50 km of the coast. When interpreting the rainfall data, it is important to note that the start and end of the rainy seasons may vary by 6 or 7 weeks from year to year. As seen in Table 1, the majority of thunderstorm activity occurs during the summer. Most of this summer rainfall occurs in the afternoon in the form of often heavy local showers and thunderstorms of short duration (1-2 hours) that are on rare occasions during the spring accompanied by hail. Summer rain which lasts for longer periods is often associated with occasional tropical disturbances. Winter rains are associated with frontal systems and are generally of longer duration than the summer rains, but are fewer in number and have a slower rate of rainfall accumulation. Hourly data taken at Tallahassee beginning in the 1940's through the 1970's demonstrate the different diurnal patterns of the summer and winter rains (Figure 20). Snowfall
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Panhandle Ecological Characterization AVERAGE ANNUAL RAINFALL 1951-1980 CENT1 METERS 0142-152 1162-172 NOAA climatological station GULF OF MEXICO Figure 18. Panhandle average annual rainfall and NOAA cllmatologlcal station locations (after Jordan 1984). occurs at rare intervals across the Panhandle, approximately 1 year in 10 for measurable falls, and approximately 1 year in 3 for trace amounts (U.S. Dept. of Commerce 1980a, 1980b, 1980~). Despite large average annual rainfalls, droughts occur (Figure 21). Even short periods of drought, when combined with the reduced area of lakes and wetlands and the low water table found during generally dry years, can cause extensive crop losses in the agricultural areas, as well as increase damage fromforest fires. Fires during extended droughts can cause severe damage even in the longleaf pine areas adapted to seasonal fires and result in the burning of parched wetlands and other habitats normally protected from fire. These areas, not adapted to the normal periodic fires of the pine forest, may recover very slowly (Means and Moler 1979). 3.2.3 Winds a. Normal wind patterns. From March through September, the Panhandle is under the western portion of the Bermuda high-pressure cell, which has a general clockwise (anticyclonic) circulation of the low-level winds (i.e., those measured at an altitude of 600-900 m) (Atkinson and Sadler 1970) (Figure 22). The latitude at which the wind shifts from out of the southeast to out of the southwest (the "ridgeline'shown by the dashed lines in Figure 22) changes substantially during spring and summer. During October through February, a western anticyclonic cell separates from the Bermuda anticyclone and establishes itself in the Gulf of Mexico (Figure 22). The center of the cell migrates somewhat as indicated by the X's, but generally results in low-level winds from a westerly direction over the Panhandle. These circulatory patterns indicate that the Panhandle is primarily influenced by tropical air masses in the spring and summer and by continental (cold) air masses during the fall and winter. The prevailing winds in the Florida Panhandle are from a southerly direction during the spring and summer (Figure 23). Locally, wind directions may be determined by
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3. Climate Maximum Rainfall over 12 Consecutive Months ALABAMA 1951 1980 Data M in imum Rainfall over 12 Consecutive Months TOTAL CENTIMETERS RECORDED 19 51-1980 Data GULF OF MEXICO Figure 19. Panhandle maximum and minimum 12-month rainfall (after Jordan 1984). 35
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Pan handle Ecological Characterization Table 1. Panhandle thunderstorm frequency statistics (Jordan 1973). Percent of Percent of Mean annual days t hunderstorrns thunderstorms with thunderstorms during June-Sept durlng Nov-Feb Pensacola 65 65 12 Apalachicola 73 73 7 Tallahassee 79 70 6 I I I I 12 6 12 6 12 Midnight AM Noon PM Midnight -1 Tallahassee Jan Feb Mar Apr May Jun Jul Aug SepOd Nov ~ecFigure 20. Percent of total daily rainfall during 125 32 28 41 37 19 o 19 68 34 26 281 individual hours of the day at Tallahassee (after Longest dry period on record beginning in month indicated I Jordan 1984). thunderhead formation and thunderstorms. Wind direction changes with the passing of each cold front; most commonly these occur during the fall and winter (September through March). As the front passes through, the wind, which normally blows out of a southerly direction, rapidly changes direction with a clockwise progression ("clocks") through the west, then pauses out of the northwest quadrant for approximately 1-3 days, blowing toward the front receding to the south or southeast. After the front has passed a sufficient distance to allow the "normal" wind patterns to reassert themselves, the wind finishes clocking through the east and back to the south. The directional orientation of the front and the direction from which the wind blows immediately following its passage depends upon the origin of the front; the winds are from the north for fronts of Arctic and Canadian origin, from the west to northwest for those of Pacific origin. This cycle is sometimes interrupted by the approach of a new cold front closely following the first. Pensacola 20-24 D~YS ............. (1.. .. ................. 27 24 28 30 29 26 18 26 49 36 23 23 Longest Dry Period On Record Beginning in Month Indicated Figure 21. Occurrence of extended dry periods at Tallahassee and Pensacola, 1950-80 [no day over 0.25 cm] (after Jordan 1984). As a result, the most prevalent winds during September through February (the season of frontal passages) are out of the northern half of the compass
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3. Climate March-September 90' 80' October-February Figure 22. Low-level (600-900 m) winds (from Atkinson and Sadler 1970). (following the fronts) with less frequent and weaker convective forces inland and because of the resultwinds from the southern half of the compass (before ing landand sea-breeze mechanism near the coast. the fronts) (Figure 24). The annual average resultant wind (i.e., the vector sum of the monthly wind speed The mean monthly wind strength is less in and direction) in the Panhandle is from the north. summer months than during the fall, winter, and This is due to the greater wind speeds that follow the spring (Figure 25). Since data for Pensacola were winter fronts than blow during the rest of the year. All unavailable, those for Mobile are included in the of these wind patterns are somewhat erratic due to figure. Inland stations exhibit somewhat lower
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Panhandle Ecological Characterization Tallahassee Pensacola Spring (March-May) Tallahassee Pen sacola Summer (June-August) Figure 23. Percentage of time wind blew from different directions in Panhandle during spring and summer, 1959-79 average (after Fernald 1 981 ). Tallahassee Pensacola Fall (September-November) Tallahassee Pensacola Winter (December-February) Figure 24. Percentage of time wind blew from different directions in Panhandle during fall and winter, 1959-79 average (after Fernald 1981). Jan Feb Mar Apr May Jun Jul Aug Sep Oct NOV Dec Jan Figure 25. Seasonal windspeed at sites in and near the Florida Panhandle (after Jordan 1973). 38
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3. Climate average speeds than those along the coast (Jordan 1973). The highest 1 -minute sustained wind speed is seldom over 50 kmlh, though sustained non-hurricane-associated winds in the 85-95 krnlh range have been recorded (Bradley 1972). These peak sustained wind speeds are generally higher at the eastern end of the Panhandle than at the western end (U.S. Dept. of Commerce 1980a, 1980b, 1980c; Fernald 1981). b. Hurricanes, tornadoes, and waterspouts. Hurricanes pose a major threat to the Florida Panhandle. A hurricane is a cyclonic storm (i.e., the winds rotate counterclockwise in the northern hemisphere) with sustained wind speeds in excess of 120 kwh. Forty-eight hurricanes have come ashore in this region from 1885 to 1985 Figure 26 shows the tracks for hurricanes hitting the Florida Panhandle during this period while Table 2 gives their monthly distribution. Much of hurricane damage is caused by the local rise in sea level known as storm surge. For hurricanes striking the Panhandle from the gulf, this rise occurs east of the "eye" (the storm's center) as the counterclockwise wind circulation about the eye pushes water ahead and traps it against the coastline. An embayment helps contain this water and can increase storm-surge magnitudes substantially when a hurricane strikes its western side. Tidal stage and phase, bottom topography, coastline configuration, and especially wind strength combine to ,ALABAMA GULF OF MEXICO 0 10 20 30 40 50 Miles Figure 26. Paths of hurricanes striking the Panhandle coast, 1885-1985 (after Jordan 1984, Case 1985). 39
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Panhandle Ecological Characterization Table 2. Total number of hurricanesand tropical Storms striking or passing within 150 miles of the Florida Panhandle during 1885-1985 (Jordan 1984, Case 1986). Jun Jui Aua Sen Oct Nov-Mav Total determine the storm-surge magnitude. The State of Florida addressed coastal safety, property protection, and beach erosion during hurricanes in Henningsen and Salmon (1981). Tornadoes and waterspouts form infrequently. They occur most commonly in the spring, associated with frontal weather systems, and in connection with tropical storms and hurricanes. Tornado paths in Florida are usually short, and historically damage has not been extensive. Waterspouts occasionally come ashore but dissipate quickly after reaching land and, therefore, affect very small areas (Bradley 1972). 3.2.4 Insolation The amount of sunlight, or insolation, reaching the Florida Panhandle directly affects temperature as well as photosynthes~s. It lndlrectly affects processes in which these factors play a role, including weather patterns, rates of chemical reactions (e.g., metabolism), productivity, and evapotranspiration (evaporation and water transpired into the atmosphere by plant foliage). The amount of insolation is controlled by two factors: season and atmospheric screening. a. Seasonal changes. Seasonal insolation 1s controlled by five factors: (1) the changing distance between the Sun and Earth as Earth follows its elliptical orbit; (2) the increasing thickness of the atmospherethroughwhich the solarrays must travel to reach the Earth's surface at points north or south of the orbital plane (Figure 27); (3) the reduced density of rays striking an area on Earth's surface north or south of the orbital plane (Figure 28); (4) the changes in cloudcover associated with the progression of the seasons; and (5) seasonally induced Figure 27. Change in length of atmospheric light path with change in distance above or below orbital plane. changes in atmospheric clarity due to particulates. Flgure 28. Change in light Intensity at Earth's Factors 2 and 3 are caused by Earth's axla1 tllt surface with change In distance above or below relative to the orbital plane and the resultant change plane. 40
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3. climate in the angle at which solar rays strike a point on the globe during Eallh's year-long trip around the sun. This change aiters the distance through the atmosphere that the rays must travel and, therefore, changes the percentage of the rays reflected or absorbed by the atmosphere. Factors 4 and 5 are products of seasonal variations in insolation upon circulation of air masses, hence the effects from insolation affect the amount of it reaching the Earth's surface. Theconcentrationof screening particulates in the atmsphere is further affected by seasonal variations in emissions resulting from human activities (e.g., smoke from heating during winter) and by the variations in the speed with which both natural and anthropogenic particulates are removed by rainfall or diluted by atmospheric circulation. b. Atmospheric screening. Absorption or reflection by water vapor, clouds and atmospheric particulates such as dust and smoke effectively reduce the solar radiation penetrating to the Earth's surface. On a clear day approximately 80% of the solar radiation entering the atmosphere reaches the Earth's surface. About 6% is lost because of scattering and reflection and another 14% from absorption by atmospheric molecules and dust. During cloudy weather another300/'0% may reflect off the upper surface of the clouds and 5O/-20% may be removed by absorption within the clouds. This means that fromO%to45% may reach Earth's surface (Strahler 1975). Thus it is clear that the single largest factor controlling short term insolation is cloud cover. The percentage of cloud covervaries seasonally (Figure 29), as do the patterns of cloud cover. The seasonal patterns of cloudiness are controlled prlmarily by extratropical cyclones and fronts in the winter, and by localized convective weather patterns in the summer. Though the fypes of clouds and rainfall patterns are different under each of these systems, they result in similar amounts of cloudiness and rainfall in winter and summer in the Panhandle. Daily cloudcovervariations are considerably greater in winter than in summer. That is, in summer many days have partialcloudcoverwhile inwinterthedays tend to be entirely overcastor entirely clear. Insouth Florida, where winter cyclones and fronts are less frequent, the winter and summer amounts differ greatly. The maximum insolation striking Earth's atmosphere at the latiude of Panhandle Florida is approximately 925 langleyslday (Strahler 1975). Figure 30 shows the seasonal variation of the daily insolation Apalachimla Pensamla ............. Tallahassee Tallahassee Satellite 1 1 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Figure 29. Mean daytlme sky cover (data from U.S. Dept. of Commerce 1980a,b,c) and Tallahassee cloud cover from 3 years of satellite data (after Atkinson and Sadler 1970).
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Pan handle Ecological Characterization Figure 30. Variations in insolat ion striking the atmosphere depending on latitude and season (after Strahler 1975). striking the atmosphere over the Panhandle region. The monthly average of the daily insolation amounts actually received at Tallahassee and Apalachicola are presented in Figure 31. In addition, the percent of possible sunshine measured at Tallahassee and Pensacola is presented in Figure 32. Atmospheric clarity over the Panhandle is, with the exception of clouds, generally very good. Occasional atmospheric inversions during summer months may result in "hazeHas natural and anthropogenic aerosols are trapped near the surface and concentrated, thereby reducing insolation. 3.2.5 Relative Humidity The Florida Panhandle is an area of high relative humidity. Relative humidity is the amount of water vapor in the air, expressed as a percent of saturation at any given temperature. Air incapable of holding further water vapor (saturated) has a relative humidity of 100%. The amount of water necessary to saturate a volume of air depends upon temperature.
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3. Climate 80 1 !! 60 m........... 1 40 2 c J 20 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nw Dec Jan Figure 31. Monthly insolation at selected sites in Figure 32. Percent of possible sunshine at seFlorida Panhandle (after Bradley 1972). lected sites In Panhandle (data from U.S. Dept. of Commerce 1980a,b,c). Air at a higher temperature is capable of holding more water than thqt at a lower temperature; therefore, air near saturation will become oversaturated if cooled. This oversaturation can produce dew, precipitation, or, when very near saturation, clouds or fog. In the seasons when prevailing winds bring moist air from the Gulf of Mexico (i.e., spring, summer, fall), humidity is often 85%95% during the night and early morning, and 50Yo-65% during the day (Bradley 1 972). High relative humidity can greatly accentuate the discomfort of high summer temperatures. There are several formulas commonly in use (e.g., Temperature Humidity Index, Humidity Stress Index, Humiture) that generate a "comfort" value based upon a combination of temperature and humidity. The afternoon Panhandle climate during June through September is usually well into the uncomfortable zone. These indices are based on the effect of humidity upon evaporation rates. The humid air flowing from the Gulf of Mexico has minimal capacity to hold further moisture. As a result, evaporative drying of wetlands and other water bodies in the Panhandle is minimized, thereby helping to maintain them between rains. Summer rains and slow evaporation also provide ideal conditions for many fungal and bacterial diseases, prominent problems in area farming (Shokes et al. 1982). Fog is common at night and in the early morning hours as the ability of the cooling air to hold water decreases and the relative humidity rises over 100%. Heavy fogs (visibility 5 0.4 km) generally form in the late fall, winter, and early spring. On the average, they occur 35-40 days per year (Bradley 1972). Apalachicola experiences fog on an average of 14% of the days in November through March, and 2% of the days from April through October (Jordan 1973). Fogs usually dissipate soon after sunrise. 3.3 Effects of Climate on Ecosystems Climate exerts control on the regional ecology through two major mechanisms. The normal climate of the Panhandle establishes the basic conditions under which all species must be able to live and compete if they are to find a niche in the ecosystem. The occasional abnormal or extreme climatic condition may prevent establishment of a species that would otherwise thrive by producing periodic local extinctions or near-extinctions. The rare severe or prolonged freeze, heat wave, drought, or flood may decimate a population so that years or decades are required for its reestablishment. No clear separation exists between conditions constituting normal and extreme climatic conditions. Regular events which are beyond a species' ability to adapt may reduce what would otherwise be a dominant organism to a minor position in the ecosystem or prevent its establishment altogether. A Panhandle example is the mangrove. A dominant species on Florida's southwest coast, mangroves are represented in the Panhandle by one small colony of
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Panhandle Ecological Characterization black mangrove on the bay side of the eastern end well as the temperature regime, are products of of Dog Island. In conditions othetwise conducive to varying insolation. mangrove growth, the occasional cold winters llmit them to this marginal colony. In contrast, an otherb. Short-term Influences on climate. Shortwise minor organism may be dominant through its term(upto hundredsof years) naturalfluctuationsin ability to survive the climatic extreme and thereby climate are generally caused by changes in insolaoutcompete ecological rivals. Relatively Small tion screening. The concentration of natural atmoschanges in the "normal" extremes of climate may pheric particles results from the balance between produce effects on ecosystem composition as large input from wind scouring (particularly of desert and as those produced by changes in the average cliotheraridregions),volcanicdustoutput,Smokefrom mate. Anexample mightbe asituationwhereaslowforest fires and volcanoes, and removal by gravitagrowing and reproducing shrub species and a fasttional settling and atmospheric scrubbing during growing and reproducing shrub species compete for rainfall. space in aforest clearing commonly visited by foraging wild pigs. All otherfactors being equal, the slowThe Panhandle, along with the rest of the northgrowing species might dominate, even though it ern temperate lands, has experienced an approxiwould be very slow to recolonize areas where it was mately 0.1 "C reduction in average temperature over dug up by the pigs, because it could better tolerate the last decade despite an increasing greenhouse the annual dry summers. An increase in the normal effect worldwide. It is probable that this is the result summer rainfall (a change in the "average climate") of. (1) the screening of insolation atthese latitudes by might leadtodominanceof thefast-growing species. increased atmospheric smoke and dust from recent The same effect might result, however, if the area increased volcanic activity and/or dust from the began to experience previously unknown hard expandingSaharadesertanddrou~htareasinNorth freezes during occasional winters (a change in the Africa, and lor (2) variation in the Sun's output climatic extremes), and the slow-growing species (Hoffman et al. 1983). These variations are historiwas killed by freezes while the fast-growing Species cally common and Titus and Earth (1984) concluded was freeze tolerant. Either change will have the thatthey were incapableof ovetwhelming theoverall greatest effect upon those organisms living near greenhouse effect. their limlts of tolerance. Periodic changes in climate and weather aff ecting the Panhandle have recently been tied to the 3.4 Major Influences on Climate phenomenon known as EI NiRo. ~hough all the 3.4.1 Natural Influences on Climate parameters of cause and effect are not yet understood, a major current off the coast of Peru, which a. Long-term influences on climate. Long drives the upwelling responsible for one of the termchanges(overthousandsto rnillionsof years) in world's largest fisheries, apparently moves well offworldwide climate are primarily a function of shore and weakens because of changes in the wind changes in the concentration of atmosphericcarbon patterns driving it. Changes in equatorial wind patdioxide (CO,) (Revelle 1982). Caibon dioxide traps terns which eithercause the shift in watercurrents or incomlng solar radiation (Hansen et al. 1981). This arecaused by the shift (which factors are cause and effect is commonly known as the "greenhouse elwhichare effect are not yetunderstood) affectworldfect." The resulting temperature increase allows the wide climate by altering patterns of rain, temperaatmosphere to hold more water vapor, itself an ture, and wind. The Panhandle may have just effective greenhouse gas, which accentuates the recovered from a period of weather in the early warming. Othergases (e.g., methane, nitrousoxide, 1980's influenced by an exceptionally strong El NiRo. chlorofluoroca~ons) act similarly, but their effects The hotter and drier summers and warmer winters are generally subordinate to those of CO, because of followed by a rebound period of spring flooding, their relatively low concentrations. The Sun "drives" heavy summer rainfall, and colder winters that have Earth's climate since the wind and rain systems, as been experienced in the Panhandle and other 44
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3. Climate unusual weather patterns worldwide have been tentatively identified as indirect effects of El NiRo. Another mechanism controlling short-term clii mate changes as wen as being involved in longterm variations is albedo, or the reflectance of a surface. The higher the albedo, the more incoming radiation is reflected and can pass through the "greenhouse" gases and out of the atmosphere. The lower the albedo, the more radiation is absorbed, reradiated as heat and trapped in the atmosphere. Snow and ice have a very high albedo; i.e., they are efficient reflectorsof solarenergy (45'/-85%). Bareground, fields and forests have intermediate albedos ranging from 3/r250/0. Unlike land, the oceans (and water in general) have a variable albedo: very low (2%) for radiation striking from low angles of incidence (i.e., with the sun high in the sky), but high forthat striking from high angles (i.e., with the sun low on the horizon). This iscaused by the growing proporlionof the light that is transmitted into thewaterat decreasing angles of incidence. Thus the equatorial seas at midday are good absorbers of solar energy, but the arctic seas are not. The significance of this in the Panhandle is that coastal waters receive more heating through insolation in summer, not only because of the increase in sunlit hours from the longer day, but alsofromanevengreaterincreaseofthetime the radiation strikes from high angles. Other local effects of albedo differences are common, as anyone who has stood on an asphalt parking lot on a clear summer day can attest. Another difference between the effects of insolation on land and water is caused by the difference in the specific heat of dry soil or rock and that of water. Water requires nearly fivetimes asmuch heat energy as does rock to raise its temperature the same amount. This, coupledwith the increased evaporativecoolingfoundatthe surface ofwaterbodies. explains the more extreme diurnal and seasonal temperature regimens found over land as compared to that over or near large bodies of water. 3.4.2 Anthropogenic Influences Human activities increasingly influence climate, although the line dividing natural and anthropogenic influences is not always clear. Global warming due to changes in the atmospheric greenhouse effect is one of the most notable results of human activities (Hansen et al. 1981, Weissetal. 1981. Broeckerand Peng 1982, Edmondsand Reilly 1982). Thischange is primarily a result of increasing concentrations of atmospheric carbon dioxide from combustion of fossil fuels as well as from the logging of enormous areas of forest, with the resultant release of GO, through the burning or decomposition of the carbon bound up in the organic matter (Charney 1979); of atmospheric methane (Rasmussen and Khalil 1981a, 1981b. Kerr 1984): of atmospheric nitrous oxides (Donner and Ramanathan 1980); and of chlorofluorocarbons (Ramanathan 1975). There was a 9% increase in atmospheric carbon dioxide between 1958 and 1985 (Figure 33). A conference was held in 1982 in response to articles in popular literature (Boyle and Mechum 1982) concerning a theory ascribing recently reduced rainfall and increased temperature in south Florida to reduced albedo and evapotranspiration resulting from the draining of area wetlands. The results of this conference are summarized in Gannon (1982). Though evapotranspiration from land masses may account foronly 5%of the precipitation in south Florida (the bulk arriving with air masses fromoverthe Atlantic), evapotranspirationincreases the buoyancy of the continental air masses. It is probable that this increases mass convergence, bringing in more moisture from the adjacent oceans and acts as a trigger to increase convection and, therefore, the convection-induced rains. Rainfall of this nature is found year round but is especially common in summer. A 70 inch rainfall deficit which accumulated between 1962 and 1982 along the St. Johns River in northeast Florida has also been attributed to the draining by 1972 of approximately 72% ol the once vast wetlands through which the river flowed (Barada 1982). If this relationship between evapotransp~ration and rainfall is confirmed, a similar mechanism probably exists in the Panhandle, where similar patterns of convective rainfall are found. Future development which reduces wetland and vegetated areas might induce similar reductions in summer rainfall. Short-term cooling trends have been attributed to insolation screening by dust, smoke, and debris thrown into the upper atmosphere by large volcanic eruptions such as Krakatoa in 1883 (Humphries 1940) and Mount St. Helens in 1980 (Searc and Kelly
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Panhandle Ecologlcal Characterization Figure 33. lncreaslng atmospheric carbon dioxlde as measured atop Mauna Loa, Hawaii (data from Charles Keeling, Scripps Inst. of Oceanography). 1980). Smaller eruptions have a weaker cooling increase in mean Panhandle temperature and afew effect. It is thought that this short-term coollng may percent increase in local precipitation (Revelle 1982, be partially masking the long-term global warming National Research Council 1983). The present causedby increasingconcentrationsof atmospheric understanding of meteorology is not, however, sufCO, (Bell 1980). ficient to permit reliable prediction of these changes. This is particularly true of climate changes over a relatively small area the size of the Panhandle. 3.5 Summary of Climatic Concerns The Florida Panhandle has three present and near-future climatological concerns. Two of these result from the present global warming trend. While all effects of this warming are not predictable withour present understanding of the ecosystem, certain effects in the Panhandle are probable. A major impact resulting from global warming is a predicted substantial rise in sea level, significant effects of which are expected within 25 years. This impact is discussed more fully in section 4.8. The second concern relating to atmospheric warming IS a probable change in weather patterns A possible 5 OF increase in the mean global temperature by the latter part of the next century is projected to yield a slmllar A f~nal cl~matic concern for the future is the possibility of reduced summer (convective) rainfall. Unlike the previous two problems, the causes have not yet been widely initiated and are preventable. Convective summer thundershowers provide the majority of summer rainfall. Summer rains, in turn, supply the majority of the total annual rainfall (Figure 17). The convective mechanismcausing these rains is similar to that found in south and east Florida. Since the "rain machine" in these regions may have been weakened by extenslve wetland draining, it is possible that future terrain alteration in the Panhandle-including drainage and development of large wetland areas--could cause a similar effect
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3. Cllr nate Predicting the occurrence and effect of climate changes is very difficult since the understanding of the meteorological and oceanographic systems that provide climatic feedback and checks-and-balances is incomplete. With these constraints, even the sea level predictions, which are based on an intensive program of study, include necessarily wide margins for error. Unexpected or unexpectedly strong feedback mechanisms may exist to damp the warming trend. One possible example of such feedback is that the increase in size taking place in our deserts (especially the Sahara) may be a result of global warming; however, the increased dust blown into the atmosphere from the larger desert area may be increasing insolation screening and therefore tending to reduce that warming The possible existence and "strength of similar feedback mechanisms make accurate prediction of future climate difficult; however, the National Academy of Sciences (Charney 1979) was unable to find any overlooked physical effect that could reduce the estimated temperature increase to negligible proportions. The accuracy of the predictions is increasing through research into the major climatic factors. 3.6 Areas Needing Research Research on numerous aspects of the Panhandle climate is needed concerning questionswhich, of course, affect much wider areas, but are applicable to this area Research is especially needed on the changing greenhouse effect; the effects of increasing world-wide average temperatures on area climate; the mechanisms controlling coastal convective rainfall; and ratesof evapotranspiration and their connection to rainfall and runoff.
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Chapter 4. HYDROLOGY AND WATER QUALITY 4.1 Introduction it cannot be used at a rate greater than the average rate at which it is replaced by rainfall. Otherwise. Water quality is, in many ways, dependent on saltwater intrusion will render the coastal wells usehydrology and frequently the forces affecting one less because the depthtothe underlying saline layer also affect the other. This chapter will discuss each is much less near the oceans. of these areas, their interrelationships, and their status in the Florida Panhandle. An excellent source . ..-,--,--.. of general information on the water resources of the *"'I nYu'u'ULJY Panhandle and all of Florida is the WaterResources Hydrology isthe study ofthewaterc~cle, includAtlas of Florida [Fernald and Patton 1984). The ing atmospheric, surface, and ground waters. The Hvdrolooic Almanac of Florida (Heath and conover basic hydrologic cycle (Figure 34) includes water 1981) has very good discussions of different hydrovapor entering the atmosphere as a result of evapoloaic and water aualitv factors as well as containin0 ration, transpiration, and sublimation. This vapor g;od, if occasio~ally dated, records on Florida. Panhandle surface water supplies and its ground water supplies are normally inseparable. In many places water flows from the surface into the ground and back again many times as it makes its way to the coast. Any changes in the hydrology or the quality of one is likely to affect the other. The entire supply of potable ground water in Floridafloats on deeperlayers of saline ground waterthat are connected with the Atlantic Ocean and the Gulf of Mexico. This layerof fresh water floats because it is -2.5% less dense than the salt water. As water is removed from the fresh-water aquifer, the underlying saltwatertendsto pushtheuppersurfaceofthe fresh-water aquifer higher asthe aquifer gets lighter As a result, "permanently" lowering the upper surface of the freshwater aqulfer by 1 It over a broad area requireswithdrawing avolumeofwaterequal to nearly 40 A of the aquifer thickness. Thus, simplistically, for every foot our pumping of the fresh-water aquiferslowers theuppersurfaceand isnot replaced in a reasonable period of time by rainwater, the deeper saline layers rise 40 it. The Florida Panhandle, and all of Florida, has tremendous volumes of fresh water stored beneath the ground; however, condenses to form fog, clouds, and, eventually, precipitation. In the Florida Panhandle precipitation normally reaches the ground in the form of rain. Snow and hailoccurinfrequently. Upon reaching the ground, the water either evaporates, soaks into the soil and thence into the groundwater system, or (if the ground issaturated or the rateof rainfall exceeds the ground's ability to absorb it) runs off or pools. forming streams, rivers, lakes and other wetlands. The fundamental organizational unit of surface hydrology is the drainage baslrl. In its most basic form, adrainage basin,orwatershed,consistsofthat area which drains surface runoff to a given point. Thus the mouth of a river has a drainage basin that includes the basins of its tributaries. The drainage areas discussed in this document are based upon the basins described by the U.S. Geological Survey (Conover and Leach 1975) (Figure 35). Most of these consist of the Florida portion of the drainage basin of a single coastal river. A large portion of many of these basins actually extends well into Georgia and Alabama (Figure 36). Some, however, represent coastal drainage areas where lands drain to coastal streams and marshes on a broad front rather than to a single discharge point.
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Figure 34. The basic hydrologic Cycle.
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Panhandle Ecological Characterlzat ion Figure 35. Panhandle drainage basins discussed in this document (after Conover and Leach 1975). 87" 06' 8 6 8 4" I 1 ALABAMA I I I I GEORGIA 1 ., GULF OF MEXICO A. Ochlockonee River D. Chipola River H. Yellow River 0 1Q 20 30 40 50 B. Coastal area between Ochlockonee E St. Andrew Bay J. Blackwater River 1 Mi'es and Apalachicola Rivers F. Choctawhatchee River K. Escambia River C. Apalachicola River G. Choctawhatchee Bay L. Escambia Bay Ground water in the Florida Panhandle is contained primarily within two overlapping reservoirs: the Floridan aquifer underlying the entire Panhandle; and the Sand and Gravel aquifer which overlies the Floridan west from Okaloosa County (Figure 37). A shallow surficial aquifer is found overlying the Floridan aquifer in many parts of the eastern Pan handle (Figure 38). L Panhandle aquifers are recharged by five means: (I) drainage of surface runoff into areas where the aquifer is unconfined (i.e., not overlain with a low-permeability stratum) and located at or near the ground surface; (2) drainage of surface runoff into sinkholes and other natural breaches into the aquifer; (3) percolation of rainfall and surface water through the upper confining beds; (4) percolation through the confining layers of water from aquifers overlying or underlying the one in question but with a greater potentiometric surface ("pressure"); and (5) lateral transport from areas within the aquifer with a higher potentiometric surface (Figure 39). Areas within the Panhandle recharging the Floridan aquifer are presented in Figure 40. 4.1.2 Water Quality The availability of water has always been an important factor in selection of sites for human activities. The primary concern of the past-securing needed quantities of water-has, in recent years, increasingly been replaced by concerns about the quality of that water. Water quality affects people directly by influencing water's suitability for drinking, cooking, bathing and recreation, and indirectly by its effect upon the ecosystem within which humanity exists. Factors affecting water quality include the physical makeup of the local ecosystem (e.g., the presence of limestone generally prevents acidic water), seasonal changes in that ecosystem, direct discharges from human sources, and indirect discharges from human sources (e.g., acid rain). Society judges water quality based upon its usefulness to people and those animals and plants
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4. Hydrology and Water Quality 0 10 20 30 40 50 1 \ Flgure 36. Out of state dralnage basins of Panhandle rivers (after Palmer 1984).
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Panhandle Ecological Characterization ALABAMA GULF OF MEXICO 0 10 20 30 40 50 L---d Miles Y7 J' Figure37. Primary Panhandleaquifers used as water sources (after Hyde 1975). north east West -East Hydrologic Cross Section sealevel ;;" North -South Hydrologic Cross Section 200JacksonC a Floridan Aquifer houn Go Ky Upper Floridan Aquifer it + "U I Lower Floridan -200Aquifer 0 . . . . ;h&yf;;d Gravel Lower Floridan ... ..... .... '.* ........ . . . ::::::=:::: Confining unit *o1 ...... .... ;;;e;;ediate L-1 ~ucatunna clay Aquifer (confln~ng ,,, ..,..: confining Unit east south Figure 38. Hydrologic cross sections of the Panhandle (after Wagner et al. 1984). 52
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4. Hydrology and Water Quality Figure 39. Potentiometric surface of the Floridan aquifer in the Panhandle in May, 1980 (after Healy 1982). I I I I -----GULF OF MEXICO 0 10 20 30 40 50 huw Miles n Generally No Recharge Natural discharge areas. Heavy pumpage may reverse gradient and induce limited local recharge. 0 Known Very Low Recharge Floridan known to be overlain by relatively impermeable and unbreached confining beds. Very Low to Moderate Recharge Floridan overlain by thinner or breached confining beds; water table higher than potentiometric surface. [7 High Recharge Well-drained upland areas characterized by poorly developed stream drainage system. Figure 40. Recharge areas to the Floridan aquifer in the Panhandle (after Stewart 1980). 53
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Panhandle Ecological Characterization we value. Since our society has come to recognize the value of a healthy ecosystem, we try to measure this health in addition to the physical and chemical water quality parameters. Increasingly this is done by examining the number and diversity of the species and individuals present in the water body. Various indices have been developed and used including numerous species diversity indices and what are known as biotic indices, which measure the presence of key species judged to be indicators of high water quality. Combinations of these indices aid inquantifyingthedegreeof ecological health, but resultsfrom any one index must be viewed withcaution. Each method, because of the manner with which it weighs different factors, generally has situations in which it gives a poor representation of the actual conditions. a. Direct Importance. The first concerns about water quality were directed toward the transmission of disease through drinkingwater. Even thisconcern is relatively new. The desirability of separating humanwastesfrom sourcesof waterfordrinking and food preparation was not understood in western civilizations until the mid-1800's and this separation was not effected on a wide scale until the early 1900's. Until the early 1970's, drinking water was routinely examined and treated primarily for disease pathogens. Only recently has an awareness of the health and environmental impacts of toxicants become widespread The majority of these substances are metals or synthetic organic compounds. Metals from natural sources in sufficient concentrationstocause problems are uncommon. Mostof the organic hydrocarbons contaminating waters do not occur naturally. The vast majorlty of toxlc substances found in the planet's waters are anthropogenic, products of modern industrialized society. Efforts to locate, identify, and remove these substances from our waters are greatly hindered by thelr enormous number and variety, thelr dlff~cult detection, and the lack of knowledge concerning both their shortand long-term effects. Some are toxic at levels below wh~ch the~r concentrations can be reliably measured. Increasing the problem of controlling these hazards is the daily discovery or synthes~s of addit~onal chern~cal compounds, many of which are a potential threat to water supplies. In addition to exposure through contaminated drinking water, some of these substances are being found in human foods following uptake by food plants or animals. A secondary problem is the need for water of sufficiently high quality to meet industrial needs. Though most industrial water uses are for cooling, steam generation, materialtransportation, and similar tasks not requiring potable water, preventing scale buildup in steam and cooling equipment and using water for product makeup and certain chemical processes may require that specific aspects of the water quality be high. b. Indirect Importance. The quality of water, both the physical characteristics and the presenceor absence of toxic components, is a factor controlling ecosystem constituents (e.g., productivity, species diversity). Just asclimate and water availability exert control upon floral and faunal composition, so does the quality of the available water. An area of poor water quality may support little or no life or, akernatively, populations of undesirable species. Humanity is at the apex of a food web pyramid and is, therefore, dependent upon the soundness of the baseof that pyramidforexistence. Ifpressed, we may be capable of treating sufficient quantities of contaminated water to supply humanity's direct water needs, however, water of the quality necessary to support all levels of the ecosystem must be available, otherwise the food web pyramid may erode from beneath us. 4.1.3 Hydrology and Water Quality Regulation and Management Though attempts are being made to treat drinking waters for contaminants, the removal of contaminants from the natural surface waters to which people are exposed during work or recreation is much more difficult to manage. It is impractical to treat surface waters to remove contaminants or alter physical parameters; rather, contaminant removal and physical changes must be performed prior to discharge of domestic or industrial eff luents. To this end, State and Federal regulations have been enacted in an attempt to control effluent discharges into surface waters. Underthe Federalclean Water Act,
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4. Hydrology and Water Quality point source discharges into surface waters of the United States are regulated by the National Pollutant Discharge Elimination System (NPDES). Underthis system dischargers are given permits to discharge effluents meeting certain standards based upon the types of waste generated. The discharger is required to monitor the effluents and report periodically. In Florida, all NPDES permit applications and reports are reviewed by the Florida Department of Environmental Regulation (FDER). Under NPDES regulat~ons, effluents should meet State water quality standards. The NPDES program, however, does not regulate dischargers in such a way that curnulative impacts are controlled. Hence, while a river may have numerous discharges into it, each meeting water-quality standards, the cumulative effect of all the discharges upon the river may cause its water quality to fail to meet standards. The NPDES program primarily is aimed at conventional pollutants, including bacteria, nutrients, and materials decreasing dissolved oxygen (DO) concentrations. Surface waters have been monitored by the FDER since 1973 using Permanent Network Stations (PNS), though this monitoring network has been substantially reduced in recent years. The responsibility for management of regional water resources is held by the Nonhwest Florida Water Management District (NWFWMD). This responsibiliy includes regulation of water consumption and long-range planning to help ensure the continuing availability of high quality water. The water management district also has its own network of monitoring stations. At the request of the State Legislature, the NWFWMD in 1979 formulated a water resources management plan (NWFWMD 1979a) and a regional water supply development plan for the Panhandle coast (Barrett, Daffin and Carlan. Inc. 1982). Waste load allocation studies have been performed by the FDER and, in earlier years, the U S Geological Survey to attempt to determine the amount of effluent discharges, including those of sewage treatment plants and private sources, that can be discharged into water bodies without degrading them. It should be pointed out that present methods of wasteload allocation rely primarily on models of DO and nutrient concentrations, are aimed at allocation of nutrient loads from public and private sources to maintain DO levels necessary for a healthy aquatic system, and are therefore incapable of predicting or allowing for effects from toxic discharges. The FDER conducts a program of acute and chronic toxicity bioassay testing on selected private and municipal effluent discharges that are recommended to them. Results of the tests are available as reports from the FDER Biology Section, Tallahassee. Primarily because of cost considerations, most data collected from the various monitoring networks and stations is physical or chemical in nature. The biological baseline studies and monitoring neededto enable accurate determination of the overall "goodness" of the water quality of a particular water body IS generally lacking. Additionally, all the large Panhandle rivers are interstate rivers originating in Georgia or Alabama. Thus, their hydrology and water quality is influenced by factors outside their Floridadrainage basins. With the notable exception of ApalachicolaBay, datalimitationsdueto changing sampling methods and uncharacterized ambient conditions have prevented long-term trend analysis in these riverbasins (FDER 1986~). Lackof baseline data In most instances and lack of continuing data collection in many instances prevent accuratedetection of changes in surface-water quality and hinders interpretation of data gathered in short-term stud~es and laboratory simulations perlormed to predict effects on area ecology (e.g.. chronic toxicity bioassays) (FDER 1985a, Livingston 1986~1). Following thediscovery in the early 1980'sof the toxic pesticides aldicarb (Temikm) and ethylene dibromide (EDB) in Florida ground waters, the Florida Legislature passed the Water Quality Assurance Act of 1983 whlch included steps to address the groundwater contamination problem. One major aspect of this act was the institution of a ground-water quality monitoring networkto be admlnlstered by the FDER. This consists of a network of existing wells plus new wells where existing ones are insufficient to permit adequate ground-water sampling,each sampled on aregularbasis. In itsfirst phase, nearing completion at the time of this writing, the FDER's Bureau of Ground Water Protection performed extensive chemical testing of ground-water samples as a pilot operationtoestablishthe necessarylocat~onsforthe monitor~ng wells, to gather mapping and water quality information (aquifer locations and water flow,
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Pan handle Ecological Characterization areas of saline intrusion, ambient ground-water chemistry), and to help locate the main areas with water quality problems. Upon completion of this step, the preliminary locations of permanent monitoring wells and the frequency of sampling needed will be determined. The ensuing program will be altered as dictated by sampling results. The groundwater monitoring network was envisioned as the source of a computerized data base helping to (1) determine the quality of water provided to the public by major well fields in the state, (2) determine the background or unaffected ground-water quality, and (3) determine the quality of ground water affected by sources of pollution. A biennial report describing Florida's ground-water quality will be made available to the public and governmental bodies to help in decision making. 4.2 Water Quality Parameters 4.2.1. Dissolved Oxygen a. DO capacities. The amount of oxygen dissolved in water can be a limiting factor for aquatic life. Dissolved oxygen levels below approximately 3-4 ppm are insufficient for many species to survive. Alternatively, supersaturated levels of DO can result in embolisms (bubbles forming within the animal's tissues) and death. The amount of oxygen necessary to saturate water is temperature dependent. Higher temperatures reduce the saturation concentration (amount of oxygen the water can hold) and lower temperatures increase it (Figure 41). At 2 OC, freshwater (at sea level) is saturated at a DO of 13.8 ppm. At 30 OC, saturation occurs at 7.5 ppm. Another major factor influencing saturation levels is salinity; high salinities reduce saturation concentrations and low salinities increase them (Figure 42). While freshwater at 2 OC is saturated at 13.8 ppm, seawater (35 ppt) at the same temperature is saturated at 9.9 ppm. To provide a clearer picture of the ability of a water body to absorb more oxygen, the concentration is sometimes expressed as percent saturation-t he percentage of that DO concentration at which the water would be saturated. b. Oxygen uptake-respiration. As a result of these factors, during hot weather, when the metabolic rates of aquatic lifeforms are highest and their oxygen demands greatest, the oxygen carrying capacity of water is lowest. This situation is accentuated in confined water bodies, such as canals, where poor circulation minimizes aeration and maximizes water temperature. The problem of the reduced oxygen capacity of warm water is compounded by two factors: algal respiration and biochemical oxygen demand (BOD). "Fish kills" caused by low DO (which may include many organisms other than fish) generally occur at night or during periods of cloudy weather. The net oxygen production by the algal population during sunlit hours changes to a net oxygen consumption during dark hours when algal photosynthesis ceases but respiration by the algae and other sources continues. 0 10 20 30 40 50 0 10 20 30 40 50 Temperature ( OC) Salinity (ppt) Figure 41. Oxygen solubility as a function of Figure 42. Oxygen solubility as a function of temperature. salinity.
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4. Hydrology and Water Quallty c. Oxygen uptake-Biochemical Oxygen Demand (BOD). BOD results from microbial and chemical consumption of oxygen during the degradation of organic compounds in the water column and bottom sediments. BOD becomes a problem when excessive organic wastes enter an aquatic system. Oxygen uptake from high BOD can reduce DO levels to nearzero. Even relatively low levels of BOD can contribute significantly towards low DO levels and resulting problems ii that BOD combines with floral and faunal respiration and temperaturesalinity interactions. As a result, fish and invertebrate kills from low DO are not uncommon, especially during summer months. Most of the oxygen dissolved in water results from gas exchange with the atmosphere except during periods of heavy algal growth. The rate at which a water body absorbs oxygen from the atmosphere is influenced by its circulation. If the oxygen must diffuse through the entire watercolumn to reoxygenate depleted bottom waters(i.e.. thewaterbody is stagnant) thenthis rate is very slow. Bottom waters in canals and other enclosed water bodies, particularly those with a high ratio of depth to width and having organic bottom sediments, are especially vulnerable to oxygen depletion. If the depleted waters are circulated to the surface, the rate of oxygen uptake from the atmosphere is greatly enhanced and pockets of anaerobic water are less likely to develop. 4.2.2 pH The concentration of hydrogen ions in water is measured in pH units. Waters of low pH (<7) are acidic, those with pH = 7 are neutral,and those with high pH (>7) are basic. The pH scale is inverse (in terms of H' ions) and logarithmic; hence waterof pH 6 has 100 times as many W ions as doesthat of pH 8. The pH of water is important biologically and chemically. Below a pH of approximately 6 harmful biological effects are felt, especially in sensitive life stages such as eggs. Below a pH of about 4, only a few specialized species can survive. The biological effects of low pH are strongly linked to other factors, particularly the nonhydrogen ionic content of the water. Thus pH exerts a strong effect ontheformof many oftheothercontents inthe water. Ammonia, for instance, is found in the form of ionized ammonia (NH,*) and unionized ammonia (NH,). The ionized form In which most ammonla is found in acidic waters is several orders of magnitude less toxic than the unionized form found in basic water. This isthereverseof thegeneral ruleofthumb that the ionicforms of substances (which often form in low pH waters) tend to be more toxic (Cairns et al. 1975). Biologically, most of the direct effects of low pH upon aquaticfauna appearto be related to problems with disruption of osmoregulation (regulating blood and tissue fluids) and control of the ionic balance of blood and vascular fluids (Leivestad et al. 1976,1980, McWilliams and Pons 1978). The pH of blood (as well as plant vascularfluids) exerts strong effects onthe ionic speciation of itscomponents (i.e., the form in which the ion is found-.g., CO, may be found in solution as CO,, carbonic acid, carbonate, and/or bicarbonate, depending upon several factors, the major one being pH). Since pH exerts strong effects on metabolic chemistry, blood and vascular pH must be maintained within relatively narrow ranges. The blood of aquatic fauna is typically separated from the surrounding water by a thin semipermeable cell wall in their gills. Species or life stages that have a high ratio of gill (or in the case of eggs, chorion) surface area to body volume generally have the most difficulty compensating for ambien1 pH outside the nominal range for their blood chemistry (Lee and Gerking 1980). In the Florida Panhandle, surface waters of low pH are generally found in swamps and swampdrainages. Figure 43 gives the normal pH levels of Panhandle sulface waters. Rain water is generally slightly acidic due to the presence of dissolved GO, (forming carbonic acid) picked up from the atmosphere. Rainwater is, however, poorly buffered (i.e., possesses few ionsthat tend to stabilize pH levels). Concerned that Panhandle rainwater may be becoming more acidic due to powerplant emissions, the State and the Florida Electric Power Coordinating Group (an organization formed by the powerplants within Florida) have undertaken broad-scope acid rain studies. These studies are attempting to determine whether the unique conditions found in Florida increase or decrease the likelihood of acid ram formation, whetherthese conditions increase or decrease the sensitivity of the ecosystem to acid rain stress, and areas in or out of the State where the effectsof Florida-caused acid rain may befell (FDER
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Panhandle Ecological Characterization 87' 86' 8S0 B 4" 0 I I -ALABAMA MINIMUM pH VALUES 0 4.0 5.0 0 5.0 -6.0 a6.0 70 GULF OF MEXICO 0 10 20 30 40 50 I MI1eS i i Figure 43. Minimum pH of Panhandle surface waters (after Kaufman 1975a). 1985b). If the rainwater contacts a substrate composed of a buffering material (in the Panhandle this is usually lirnestone--calcium carbonate, CaCOJ, then the pH moves toward what is known as the equilibrium pH for that buffering reaction, that is, toward the pH at which water in contact with that particular buffer will eventually stabilize. However, if the water contacts only organic and insoluble substrates (e.g., swamps and marshes), then it becomes quite acidic (pH 4 or below) from the organic acids created by the decomposition of the vegetation, and the entire system stabilizes at a low pH. These conditions yield community structures entirely different from those found in water of higher pH, since many species are excluded by their lack of tolerance for the acidic conditions. The pH of water bodies originating in these organic wetlands often increases downstream because of the input of buffering ground water or surface drainage (or both) or from contact with a buffering streambed. Carbonate buffering in north Florida ground water is sufficiently strong that the addition of 5Y0-10% of a moderately alkaline ground water (pH approximately 8.0, alkalinity approximately 120 mg/l) has been shown to raise swamp water with a pH of 4.0 and an alkalinity of 0 mg/l to a pH of G6.5 and alkalinity of 6-12 mgll (FDER 1985a). Since the pH scale is inverse logarithmic, the 5%-10% ground-water addition, as a result of chemical buffering reactions, reduced the concentration of hydrogen ions by 99% or more. In the Florida Panhandle, pH is almost entirely controlled by the water's carbonate concentration (Kaufman 1975a). Because of the substantial buffering effect of the high ion content of saltwater, marine pH levels are generally near 8. Thus problems from low pH are rare in estuarine and marine waters.
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4. Hydrology and Water Quality 4.2.3 Turbldlty and Sediments sediment creates a mud bottom. Aquatic plants are Turbidity is the result of particulate and colloidal solids suspended in the water and is measured as the proportion of light that is scattered or absorbed rather than transmitted by a water sample. High levels of turbidity are found in streams that carry heavy sediment loads. This sediment is derived from runoff and much of it, particularly that present during periods of light to moderate rainfall, is commonly the result of human influences on the terrain along the tributaries (e.g., land clearing, urban stormwater drainage, farming without erosion control). In the absence of these anthropogenic influences, heavy rains may still temporarily increase turbidity by washing larger particles into streams, rivers, and lakes. These, however, tend to settle rapidly. High levels of turbidity may kill aquatic organisms by clogging gill structures, causing suffocation. Hard-bottom benthos can lose habitat if settling often affected by increases in turbidity-by being buried in deposited sediments or by reduced light levels. Turbidity is a concern in drinking water because it can harbor pathogens and protect them from sterilizing efforts (e.g., chlorination). High turbidity in drinking water sources, therefore, usually necessitates that the particles be removed prior to sterilization. 4.2.4 Dissolved Solids The term "dissolved solids" refers to the total amount of organic and inorganic materials in solution. The dissolved materials found in Florida surface and ground waters are primarily the carbonate, chloride, and sulfate salts of calcium, sodium, and magnesium. Dissolved solids in both surface and upper ground waters are usually below 200 mgll except for ground water along the coast (Shampine 1975a, Swihart et al. 1984) (Figure 44). Deeper 87" 86' 85" 8 4' I ALABAMA f--J 100-200 mg/l 0 ~ess than 100mg:I GULF OF MEXICO 0 10 20 30 40 50 Mi'es Figure 44. Concentrations of dlssoived solids in Panhandle surface waters (after Dysart and Goolsby 1977).
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Panhandle Ecologlcal Characterization ground-water layers usually contain more dissolved solids than the upper layers. The major ions commonly found in Panhandle waters are those often measured as alkalinity (HCO; and SO,-, bicarbonate and sulfate ions). hardness (Ca++ and Mg", calcium and magnesium ions), and salinity. The total dissolved-solids concentration in surface water is generally highest during low-flow conditions (Kaufman 1975b, Dysart and Goolsby 1977). Conductivity is a commonly used measurement which is indicative of the concentration of dissolved solids. Distilled water is a very poor electrical conductor and ions in the water improve this conductivity. Dissolved solids concentrations can usually be reliably estimated by multiplying the COndUCtlVlty In pmhosby afactorrangingfromo 55100.75,depending on the water body (Dysart and Goolsby 1977). a. Alkalinity. The concept of alkalinity is simple, thoughthe chemistry involved can be quite complex. Alkalinly is a measureof the ability of awatersample to neutralize acid, in terms of the amount of H+ (acid) that can be added to the water before the pH is lowered to some preset value (depending upon which type of alkalinity measurernent is being performed). For the most common type of alkalinity measurernent (total alkalinity), this pH is4.5. Ions in the water that tend to keep the pH high increase alkalinity and thus "buffel" the pH. Buffering ions commonly found in Panhandle surface and ground waters include carbonate (usually as bicarbonate) and sulfate. These components are generally the result of the dissolution of the limestone matrix with which the water has been in contact. The ready solubility of lirnestone and the frequent input of ground water (which has generally had significant contact with lirnestone) to the surface waterstendsto resul in Panhandlesurfacewatersof at least moderate alkalinity. AS mentioned in the discussion of pH, alkalinity in Panhandle water is very highly correlated to pH. The various forms of carbonate found in the waters are by far the predominant pH buffering agent; sulfate and other buffering ions are substantially less common (Kaufman 1975a,b, Shampine 1975a). Since the alkalinity ot Panhandle waters is overwhelmingly a function of the carbonate concentrations, many studies (partcularly of ground water) do not measure alkalinity as such, but rather record bicarbonate concentrations. In surface waters total alkalinity IS more commonly measured because of the increased likelihood that they may contain additional buffering ions caused by surface drainage and input of human effluents. Alkalinity IS not a water quality factor of importance in marine waters because, though high, it is constant. b. Hardness. The hardness of water, like the alkalinity, is generally of concern in freshwater only. Hardness is a measure of the cation (positive ion) content of water In the Panhandle the major freshwater cation is Ca", with Mg++ a distant second. Since calcium carbonate (Ilmestone) supplles most of the dissolved ions in surface and ground waters, total dissolved solids, alkalinity, and hardness are onen hlghly correlated. The hardness of natural Panhandlewaters can be reliably estimated fromthe total dissolved-solids values (Figure 44). Hardness is usually reported as equivalent concentrations of calcium carbonate (e.g 120 mgll as CaCO,). High levels of hardness (7 approximately 2,000 mglt) are unpalatable but not generally harmful, except for a laxative effect in first time users (Shampine 1975~). One aspect of hardness that is of interest is its relat~onship to soap and detergent usage. Soap combines with and precipitates hardness ions until they are removed. Only then do lathering and cleansing occur. Harder water, therefore, requires use of more soap than does soft water. Hard water also increases the rate of lime formation within plumbing and heating equipment and, where high, may necessitate the use of chemical softeningtechniques to minimize maintenance. c. Salinity. Salinity is the concentration of "salts" dissolved in water. This term is generally used to describe estuarine and marine waters, though very low concentrations of salts are present in freshwaters. Sodium (Na') and chloride (Ct) ions provide about 86% of the measured salinity; magnesium (Mg++) and sulfate (SO,-) account for another 1 I%, with the remaining 3% consisting of various mlnor salts (Qulnby-Hunt and Turekian 1983). Technically, the measurement of salinity has been defined based upon the chlorinity, or chloride
PAGE 83
4. Hydrology and Water Quality (Ct) content of seawater. This was done because of the ease and accuracy with which CI-concentrations can be measured, and because the proportions of all the different salts present in seawater are very constant. The total wncentrationsof thesesalts are approximately 1 O3 to 10" times those found in freshwaters. As a result, the chemistry of the freshwater flowing into an estuary does not significantly affect the proportions of the salts in the estuarine waters. Salinity is a factor in water quality since salinity tolerance can limit the species found in a given salinity regime. Addilionally, sudden or large changes in salinity can be stressful or fatal to the biota. The salinity tolerances of aquatic biota separate them into three main groupings: freshwater (salinities below 0.5 ppt). estuarine (0.5 to 30 ppt), and marine (greater than 30 ppt) (Cowardin et al. 1979). In general, the freshwater and marine species have narrow salinity tolerances while estuarine species are characterized by their tolerance to changing environmental conditions, including salinity. Estuaries, where fresh river waters mix with salt water, regularly present rapidly changing salinity conditions. As a result, this habitat has lower species diversly than do more stable ones, althoughthis does not imply fewer individuals. Despite the harsh physical regime, abundant dissolved nutrients promote high primary productivity that can support a large number of individuals of tolerant species. Separation of populations based on salinity tolerance applies equally to coastal wetlands. The salinity of Panhandle coastal and estuarine waters is extremely variable. These waters function as a mixing zone for freshwater runoff from surface and ground waters (0 ppt) and the offshore marine waters (35 ppt). In general, estuarine salinities range from o ppt throughout the estuary during high river stages, to 32-35 ppt within the estuary (but away fromthe river mouth) during periodsof low river discharge. The coastal waters between the estuaries often receive somefreshwater~not during rainy periods; however, the salinity regime is much more stable than that of the estuaries, and diurnal salinity changes are minimal or nonexistent. d. Nutrlents. The nutrient content of water primarily affects water quality when high concentrations promote excessive growth of algae and higher plants. Too much eutrophication (i.e., nutrient enrichment) causes excessive plant growth and the resulting increased organic load depletes dissolved oxygen, renderingthewater less suitable for species considereddesirable to people. The primary limiting nutrients (i.e., those that, when lacking, commonly limit algal and plant growth) are nitrogen (as ammonia, nitrite, and nitrate), phosphate, and, for diatoms (which often constitute the majority of fresh and salt water phytoplankton), silica. There are many more required nutrients: however, their availability is normally such that they do not prevent growth. In addition to excessive plant and algal growth, high concentrations of nitrates in drinking water also cause a serious and occasionally fatal poisoning of infants called methemoglobinemia (Slack and Goolsby 1976, Phelps 1978a). In a natural surface-water system, nitrogen as a nutrient is derived from organic debris that is carried by runoff from surrounding terrain and from aquatic species of nitrogen-fixing plants and bacteria, and is regenerated within the system through the decay of dead plants and animals. These sources are often augmented, sometimes heavily, by human effluent discharges. The most common of these are sewage treatment plants, septic tanks, and runoff fromfertilized fields. Phosphate and silica are derived, in an undisturbed system, from the weathering of continental rock. They are both recycled repeatedly through the cycle of death, decay, and subsequent uptake. Florida has extensive areas of phosphorus rich limestone matrix deposited during periods when the State wascovered by shallow seas. The dissolution of this rock and its transport into both ground and surface waters provide a ready source of this nutrient in many Florida waters. The major anthropogenic contributors include municipal sewage treatment discharges (less of a problem since the mandatory reduction of phosphate concentrations in detergents), ~noff from fertilized agricultural fields, and effluent from phosphate mining operations. There is little input of anthropogenic silica.
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Panhandle Ecological Characterization The limiting nutrients are not needed by algae and plants in equal proportions. Whlle the proportions utilized vary widely between species and depend upon environmental conditions, an average ratio of N:P = 10:l for higher plants and algae and N:P:Si = 15:1:50 for diatoms can be used. 4.2.5 Temperature Temperature affects waterquality by acting as a limitinq factor if too hiqh or too low for survival of a specific organism, aid by influencing the rate of many biological and chemical processes including metabolism. In general, hlgher ternperatures increase the rate of metabolic functions (including growth) and the speed of other chemical reactions. This tends to increase the toxic~ty and rate of metabolic uptake of toxicants (Cairns et al. 1975). Therefore, for those toxicants which are bioconcentrated (accumulated within the tissues), higher temperatures will result in higher concentrations in living organisms. Depending upon the size of the water body and how well mixed it is, the watertemperature may take minutes or weeks to adjust to the average air temperature This lag time damps water temperature fluctuations relative to air temperature fluctuations and helps mlnlmlze the stress on aquatic lifeforms. In additionto the seasonalfluctuatlons,thereare often diurnal fluctuations, particularly where turbidor dark, tannic swamp waters are exposed to sunlight. When the angle of Incidence is small, water, as well as many of its contents, absorbs solar energy very efficiently. Dark coloration improves the eff~c~ency slightly, but restricts light penetration, and therefore heatingof the water, to nearthe surface. As a result, surface water can become quite warm, while much cooler water may exist below a shallowthermocline. Freshwater surface temperatures vary depending upon season and the volume, depth, and location of the water body. Estuarine areas show the most Locally, surface-water ternperatures may be strongly influenced by ground-water input. Groundwater temperatures tend to remain very near the mean annual temperature of the above-ground climate. This is another example of temperature damping on a larger scale, the result of the slow rate at which the earth changes temperature. Where ground waterflows info surface waters, thetemperature of the water near the ground-water input will be relatively stable. Temperature becomes a water quality problem when it is too wld or warm to support a normal ecosystem. Low-temperature kills are almost exclusively a natural product of winter cold spells and are of short duration and temporary effect. High temperatures, however, can become a long-term problem when large quantities of water used to wol power plants and other industrial operations are discharged into surface waters It is not uncommon for thermal effects to be felt over a large area where substantial quantities of heated water are discharged. 4.2.6 Other Contents This catchall grouping includes many parameters of great concern. Among these are: toxic substances such as ammonia, pesticides, and metals (e.g., lead, mercury); carcinogens (cancer-causing agents), mutagens (DNA-altering agents), and teratogens (agents causing abnormal growth or structure); and infectious agents (bacteria and viNses). Many substances fit within two or more of these categories. Metals and many of the toxic compounds in water are often found in ionicforms. Most pesticides and toxic organic compounds, however, do not require ionization to be toxic. Many toxicants, Ionic or not, interfere with normal metabolic processes by displacing critical metabolites and thereby blocking reactions necessary for the maintenance of Ilfe. complex and rapid variations in water temperatures. While many ions are not toxic (at least at the The dynamics of freshwater inflow temperatures, concentrations at which they are normally found). coastal marine water temperatures, density stratifithe ionic forms of many elements and compounds cation, tide, and wind determine the proportions of are generally more reactive than are the nonionic fresh water and saltwater present at a site within an forms. Additionally, different ions of the same subestuaryandmayexposetheinhabitantstoveryrap~d stance may vary in their toxicity. Generally, the temperature fluctuations. higher the valence number (i.e., the number of
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4. Hydrology and Water Quality charges on the ion), the more toxic the ion. As a rule, low pH increases ionization and, therefore, the toxicity of many substances. The total concentration of the subject compound, along with other factors such as pH, temperature, ionic strength (i.e., the concentration of all ionic forms present), and the presence of natural (and anthropogenic) chelating agents such as tannins and lignins, combine to determine the concentrations at which the various ionic and nonionicforms of a compound will be found. Since the toxicity (if any) of that compound is affected by its exact form and availability for uptake, and since the mode of that uptake varies widely between species, predicting the toxicity of effluents being discharged to surface and ground waters is very difficult. The conditions found in the area of each discharge play an important role in determining the effect of an effluent on area ecology. This is further complicated by the long period after exposure which may elapse before the onset of symptoms, especially common in the carcinogens, teratogens, and mutagens. Since these conditions typically fluctuate, sometimes widely, during the year, it can be seen that predicting pollutant impacts can be very difficult. 4.3 Major Influences on Surface Water 4.3.1. Major Influences on Surface-Water Hydrology a. Natural factors affecting inland surfacewater hydrology. In drainage basins not subjected to major human alterations, such factors as climate, season, geology, and surface features control the hydrology. In the Florida Panhandle, climate and season combine to control precipitation, evaporation, and evapotranspiration rates, thereby determining the proportion of water contained in each step of the hydrologic cycle. The geology and topography control flow rates by determining surface porosity, slope, and erosion features. These flow rates are further modified by the presence and types of vegetation that impede runoff. Flooding is one of the most striking hydrologic events. Panhandle rivers flood primarily during the frontal rainfalls of late winter and early spring (February-May ) (Palmer 1984) (Figure 45). While this -. an' ~eb' Mar' Apr' Mai ~unJul AU~~ep 0ctNovD& an Figure 45. Seasonal riverflow in two Florida Panhandle rivers (data from Livingston 1983, Palmer 1984). difference is partially due to the winter rainy period, Figure 17 in the climate chapter shows that the total rainfall during the summer is much greater. The vast quantities of water evaporating from the warm surface waters and transpired from the lush foliage return most of summer rainfall to the atmosphere (Mather et al. 1973), thereby minimizing flood-inducing runoff. While the large Panhandle rivers show this relationship (Figure 46), they also show reduced flow during the summer rainy season because much of their drainage basins are sufficiently far inland that they receive little of the convection-induced summer rains. The reduced foliage present in winter and early spring allows a greater proportion of the rain falling during the winter rainy season of the northern regions to run off and may result in flooding. Rainfall Jan Feb Mar Apr May ~un Jul Aug Sep Oct Nov Dec Jan Figure 46. Apalachicola River f low and rainfall at city of Apalachicola (data from Livingston 1983).
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Panhandle Ecological Characterlzatlon Periodic floods are a necessary and important part of wetland energetics. Seasonal inundation of river flood plains and coastal marshes flushes organic matter produced by these wetlands into streams, rivers, and estuaries where it provides a substantial portion of the energy driving the food chain. The goal of minimizing property damage from flooding while maintaining high water quality in surface waters is best achieved by discouraging development in river flood plains and controlling construction of what development does take place to minimize damage to the resulting structures and to the flood plain (e.g., requiring that buildings be constructed on pilings above flood levels and that flood plain terrain and vegetation be maintained). Maps delineating the 100-year flood plains in Florida were drawn by the U.S. Geological Survey and are currently distributed by the Florida Resources and Environmental Analysis Center (FREAC) at Florida State University. These maps are based upon the USGS topographic quadrant maps and have too much detail to present here. It is probable that, because of changes from continuing development and other factors, these maps underestimate the areas that would be inundated by 100-year floods. Panhandle springs moderate the flow of those rivers and streams receiving their waters. The ground-water levels controlling the rates of spring flow and ground-water seepage tend to respond slowly to rainfall changes, thereby establishing a minimum streamflow ("base flow") when surf ace runoff is minimal. This moderating tendency is less noticeable during periods of high runoff and streamflow. However, many springs become siphons under these conditions and carry surface water directly to the aquifers (Ceryak et al. 1983), thereby reducing the peak streamflow somewhat. First and second magnitude springs (>30 m3/s and 3-30 m3/s, respectively) (Figure 47) are most numerous in the Figure 47. Locations and magnitudes of major Panhandle springs (after Rosenau and Faulkner 1975). 64 87" 86" 85' 84O I I I ALABAMA GEORGIA a Less than 10 ft31sec 0 10-100 ft3/sec A Greater than 100 ft3/sec GULF OF MEXICO 0 10 20 30 40 50 b-w Miles
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4. Hydrology and Water Quality central Panhandle and are located primarily along the Choctawhatchee and upper Chipola Rivers and Econfina Creek. Third magnitude springs (<3 m3/s) are less concentrated but are generally more common east of Walton County. b. Natural factors affecting coastal surface water hydrology. Coastal waters are affected by several forces that have little affect on the freshwaters inland. In shallow nearshore areas such as those common along the eastern Panhandle coast and in estuaries, wind is the major factor driving water circulation (Williams et al. 1977, Livingston 1983). This results in a net long-term movement of water west along the coast during the late spring. summer, and early fall and east along the coast during the winter months. Shorl-term currents are quite variable and depend primarily upon: (1) local wind direction, (2) tide-induced currents, (3) proximity to river mouths and the estuarine currents resulting from the density differences of the mixing fresh and sail water, and (4) the possible presence of eddies spun off of the Loop Current In the Gull of Mexico. (1) During much of the year, local wlnd direction is affected by the convective phenomenon driving the land breeze and sea breeze. Wind strength and direction and the resulting force exerted on the surface waters often changes over short periods of time. Chapter 3 contains more information on seasonal changes in wind strength and direction. (2) The Panhandle coast experiences unequal semidiurnal tides; i.e., two high and two low tides daily, eachof diiferent magnaude. This pattern is the resuil of a complex combination of forces, the gravitational pull of the Moon and the Sun being the primary ones. The period of the tides is such that they are approximately one hour later each day. The net tide-induced current is weakly west along the coast (Batlisti and Clark 1982). 01 more importance to the nearshore hydrology and water quality, the (normally) four times daily change of direction of this movement of water induces substantial mixing of the nearshore and offshore waters. (3) A number of current-pmducing and -affecting forces are in action at the mouths of rivers. Among themare (a) thefrictionof the riverflow upon the salt water it enters. (b) salt-wedge circulation, and (c) geostrophic forces. The friction of the flow exiting the river mouth attempts to "drag" adjacent saltwateralongwiththe body of riverwater, inducing eddies along the transitlon zone between the two water masses. A salt wedge forms because fresh water flowing out of the rivers is less dense than the salt water into whlch it flows; thus the fresh water tends to form a layer flowing over the top of the densersaltwater(Figure 48a). This underlying layer of salt water is called a salt wedge, and slnce the upstream end of this wedge has a lower salinity (is less dense) from mixing with the overlying river water, pressure from the denser salt water behind it forces the wedge upstream In shallow, so-called well-mixed estuaries (the type found along the Panhandle coast), turbulence and other m~xing forces tend to minimize the distance over which these two water masses remain unmixed. However, the mechanism is still functioning and an important part of estuarine hydrology. As the saltwater mixes with the overlying fresh water at their interface, the brackish water formed is less dense than the salt water and is caught up in the outward flow of fresh water and carried out toward the gulf. This loss of Saltwater from the wedge induces a flow of saltwater from the gull to replace it. Thus the estuary experiences a net outflow in the surface waters, and a net inflow in the bottom waters. This inflow can be several times the volume of the riverflow before it enters the estuary (Knauss 1978). What are perceived as small changes in river flow can result in large changes in estuarine and nearshore circulation. Others factors in estuarine circulation are those caused by Coriolis and geostrophic forces. The Coriolis 'Yorce" in the norlhern hemisphere is felt as a force directed to the right of the direction of water flow. The result of this force, when applied to an estuary exhibiting Stratified salinity, is that inflowlng fresh surface water tends to collect on the right side (relative tothedirection offlow) of the estuary (Figure 48b). In the Panhandle, the resulting thicker layer of fresh water is then forced west along the coast by geostrophicforces caused by the pressure from the denser, more saline waters to the south or east. These lwo forces, in the absence of strong coastal currents, cause the outflow of rivers in the Panhandle to tend to curve to the right once they reach
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Panhandle Ecological Characterization Figure 48. (A) Formation of a salt wedge and "stacking" of freshwater layer to right of flow direction at river mouths. (B) Coriolis and geostrophlc forces affecting fresh water flowing from river mouths. 66
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4. Hydrology and Water Quality the ocean (Knauss 1978). Once free of the river banks, these forces will tend to keep the surface layer of freshwater 'pinned"to the coast and force it west along the coast until mixing destroys the stratification. The magnitude of the effect of these forces on coastal and estuarine circulation depends strongly on the presence or absenceof mixingforces atthe time, thusthey are continually in astateof flux. A final influence on coastal hydrology is wave mixing and erosion. Wave motion does not resun in significant lateral movement of water: however, the area through which the stream or river flows during high water conditions. This area, the floodplain, is the width of river channel required to carrythe runoff during periodsof heavy rainfall in the basin. After this floodplain is developed, which commonly includes reducing its width by dumpingfill along its borders, the increased runoff resulting from the development must now flow through a more restrictedchannel. As a resultthe height offlooding is increased even more. The increased rate of runoff in developed basins also increases erosion, which further reduces landcover and retentionof rainwater. vertical mixing takes place to a depth approximately twice the wave height. In shallow areas such as the d. Anthropogenlc factors affecting coastal eastern Panhandle nearshore region, large storminduced waves caused the waters to be well mixed top to bottom. During periods of wave heights greaterthan approximately 1 m, therefore, the eastern Panhandle coastal waters would be expected to exhibit verylinietemperatureor salinity stratification. c. Anthropogenlc factors affectlng Inland surface-water hydrology. Development often substantially alters surface drainage. In the Panhandle these alterations include river damming, streamflow diversion, river channelization, dredgeand-fill activities, '?erraforming," increasing runoft (e.g., stormwaterdrainage), wetlanddraining, tloodplain development, and extensive landclearing activities. The most common results of these alterations are increased magnitude and duration of flooding and the decreased water quality of runoff. Undeveloped uplands in drainage basins act as a buffer to runoff, absorbing the initial rainfall and impeding the rate at which excess water runs off. Developed lands generally have a much reduced ability to absorb rainfall due to the reduced amount of absorptive "litter," reduced permeability of the land surface, and reduced evapotranspiration due to lower foliage densities. In addition, most development includes measures such as regrading of the terrain and installation of drainage ditches and culverts, ail aimed at speeding the rate of runoff. As a resuit, the streamflow in developed basins following periods of rainfall tend to peak rapidly and at a much higherievelthan it does inundeveloped basins. This is caused by a greater total volume of water draining into the stream or river over a shorter total period of time. Thls problem is further exacerbated by the tendency of developed drainage basins to restrict surfacewater hydrology. Human alteration of freshwater input can also alter coastal estuarine systems. Diversion of surface waters to different drainage basinsand alterationofthedynamicsof the hydrologic cycle by anthropogenic activities (e.g., consumptive water use) can cause profound changes in patterns of freshwater flow to estuaries and coastal marshes, with potentially devastating results. It has been previously described how river outflow induces circulation and mixing in water masses many times greaterthanthe volumeof water discharged. Thus the size of an estuary iscontrolled by the volumeof freshwaterinflow, butany decrease of inflow causes a much larger decrease in the volumeoftheestuary. Maverage flow intoan estuary decreases, then decreases in estuarine product~vity disproportionate to the volume of fresh water diverted can be expected. 4.3.2 Major Influences on Surface-water Quallty a. Natural factors affecting inland surfacewater quality. The major natural influence governing surface water quality is the progression of the seasons. Surface waters are commonly composed of some mixture of excess rainwater drained from surrounding lands, flow trom the Surficial Aquifer, and artesian flow trom the Floridan Aquifer. Seasonal factors which affect surface water quality include rainfall, airtemperature, and nutrient sources "Normal" rainwater is slightly acidic w~th a very low concentration of dissolved minerals (i e soft water). The water is poorly buffered and the pH is easily changed by the materials it contacts. During the rainy seasons. surface streams, rivers. and lakes
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Panhandle Ecological Characterization are composed primarily of rainfall runoff, withground water constituting a relatively small proportion. The rainwater picks up tannic and other organic acids through contact with organic debris during runoff, particularly that encountered during the relatively long periods of retention provided by swamps and marshes. This swamp runoff is acidic (pH 4-5) and highly colored, with a relatively low DO and a very low concentration of dissolved minerals. During periods of low rainfall, ground water makes up an increased proportion of most surface waters. Since ground waters are frequently highly filtered and have spent time in contact with the minerals composing the aquifer matrix (primarily limestone), they are generally colorless, moderately alkaline, and contaln moderate to hlgh levels of dissolved minerals. Since surface runoff often has weak organic acids acting as buffers, the pH of surface water mixed with a small amount of ground water can change radically. As a result of these factors, surface water chemistry (especially pH) tends to reflect seasonal rainfall patterns. providing shelter and food for detritalfeeders as well as nutrients for primary production. b. Natural factors affecting coastal surface water quality. The water quality of nearshore waters is subject to many of the same climate induced changes that affect inland waters; however, by virtue oftheirvolume, the coastal waters are more resistant to change. Nearshore water quality is primarily determined by the mixing dynamics resulting from the previously discussed hydrologic factors. These factors control the mixing of the fresh water draining off the land and the marine waters offshore. One relatively common event which is harmful to the ecology occurs when conditions encourage plankton blooms. The exact causes triggering these bloomsare notfully understood; however, thedense blooms introduce metabolic byproducts that are toxicto many species and can produce fish kills. The BOD from these kills, along with the enormous respiratory oxygen demand of the plankton at night and during overcast periods, can resun in low levels of dissolved oxygen, increasing the kill. These problems areworst inconstrictedwaters nearshore. In addition to the direct correlation between air temperatureandwatertemperature,airtemperature '' Anthropogenic factors affecting "land has many indirect influences on surface water, As Surfacewater quality. Until recently, point-source discussed previously, ambient temperatures affect ~~llutantdischarges have beenthe major human-inchemical reaction rates and equilibria reactions in duced cause of water quality changes. In the Panwater, AS a result, rates of bioconcentration oftoxics handle, much of which is relatively UndeveloPed, are higher in warmer water, as are rates of nutrient private and municipal sewage and discharges are production and Anotherfactor influenced the most common point-source effluents. Industrial by air temperature is plant growth. activity is generally found in the western portions of the area. These sources, fewerin number but which Seasonal change in ambienttemperature is one of the prlmary factors controlling plant and often animalgrowth and reproduction, bothin thedrainage basin andwithinwaterbodies. The growthand death of biota are majorfactorsm nutrientcyclingand inthe levels of dissolved nutrients found in surface Waters. Nutrient levels tend to decrease during periods of maxlmal population growth and increase during periods when deaths (and therefore nutrient regeneration) exceed reproduction and growth. Surface runoff leaches nutrients from upland Iltter, wh~ch are then carried to downstream water bodies Add~tionally, some of the litter is carried into the water, where it settles tothe bottom and decays, may have substantial local impact, include discharges from powerplants, chemical factories, paper mills, and mining operations. Discharges from powerplants are primarily in the form of thermal effluents, i.e., water that has been used to cool the generators. Nonpoint-source pollution is considered by the FDER to be a major, but largely uncontrolled, cause of surface water degradation. It is estimated from Studies that nonpoint sources contribute 450 times more suspended solids, 9 times more oxygen-depleting materials, and 3.5 times more nitrogen than point sources (FDER 1986~). The major nonpointsource pollutants in Panhandle rivers are pesticides. animal wastes, nutrients, and sediments. The major
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4. Hydrology and Water Quality causes of nonpoint-source pollution in southeastern U.S. river basins are agriculture (affecting 62% of basins) and urban stormwater runoff (affecting 57% of basins), with silviculture (tree farming), landfills. and septic tanks affecting 33% of the basins (U.S. EPA 1977). Nonpoint-source pollution is expanding and has the potential to nullify waterquality gains being made through the reduction of point-source emissions. d. Anthropogenlc factors affectlng coastal surfacewater quallty. The primary impact of humanactivitiesoncoastal waterquality resultsfrom the restriction of water circulation in dredged or otherwise altered areas. This may result in high temperatures, low DO, and salinity alterations. One of the greatest effects of human activities results from salinity alterations caused by the changes in hydrology previously described in 4.3.l(d). The factors affecting inland surface-water quality may affect local coastal water quality, particularly in the estuaries. 4.4 Major Influences on Ground Water 4.4.1 Major Influences on Ground-water Hydrology a. Natural factors affectlng ground-water hydrology. Inthe absenceof cunural impacts, groundwater levels are a function of rainfall. Ground-water levels respond to area-wide rainfall with a lag time of up to several weeks (Ceryak 1981). Since substantial lateral transpoct is possible, levels tend to follow fluctuations in rainfall averaged over substantial areas (up to thousands of square kilometers). Ground water movement is from areas of high to those of low potentiometric surface (Figure 39). Recharge of the Floridan Aquiferfrom rains and infiltrationof surface water depends on the permeability andthickness ofthe overlying strata and, where there is a surficial aquifer, depends upon the difference in head pressure betweenthisoverlying aquifer and the Floridan Aquifer as well as on the permeability of the confining layer separating them. During periods when the Floridan Aquifer's potentiometric surface is locally low, rains may cause the Surficial Aquifer's pressure to be greater than that of the Floridan, with subsequent downward percolation to the Floridan. At other times, however, the potentiometric surface of the Floridan may be greaterthan that of the Surficial Aquifer and no recharge to the Floridantakes place. In this situation, waterfromthe Floridan Aquifer may seep upward into the Surficial Aquifer. In instances where the Floridan Aquifer is confined and its potentiometric surface is above the land surface or above the level of overlying surface water, springs and seeps may flow from the aquifer andtind theirway into surface waters. High surface water levels (i.e., floods) andlor low ground-water levels may convert the springs into siphons, thereby draining surface waters directly into the aquifer (Ceryak et al. 1983) (Figure 49). This iscommonfor the springs along many rivers and, in the instances of springs flowing through large underground passages, may allow substantial volumes of surface water to mix with ground waters, increasing the opportunity for large-scale contamination of ground waters with surface pollutants. b. Anthropogenlc factors affecting groundwater hydrology. Ground-water levels are affected, often extensively, by human activities. Four major impacts presently exist in the Panhandle: (1) ground water withdrawal; (2) drainage wells, (3) pressure inject~on wells; and (4) surface hydrology alterations. (1 ) Ground water withdrawal tends to lower the potentiometric surface in the immediate vicinity of a well. As a result, ground water tends to flow laterally toward the pumped well to 1111 the potentlometrlc "hole." or cone of depression The rate of th~s flow depends upon the local permeability of the aquifer and the pressure gradient between the well and the surrounding aquifer. Another factor affected by ground-water pumping is the depth to the saline layerunderlyingthefresh-wateraquifers. Especially near the coast, excessive pumping of ground water results in saline intrusion into the potable aquifer. Because the density difference between the freshwater aquifers and the deeper saline ground waters is minimal, the permanent lowering by 1 ft of the upper surface of the Floridan fresh water indicates that approximately 40 ft of of the fresh water was removed andthatthe upper surface of the underlying saline aquifer rose nearly 40 ft.
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Panhandle Ecological Characterization round water Mconf~n~ng Layer Figure49. Generalized relationship of surfacewaterto groundwaterfor spring sand siphons. 70
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4. Hydrology a1 id Water Quality (2) Drainage wells have been used extensively in some areas to drain perennially-wet orflood-prone areas. These wells aredrilled into anaquiferandthe boreholes left open. "Excess" surface drainage is then directed to the holes. It is also common, in suitable areas, that sink holes connecting to ground water are used in place of drilled wells. The use of drainage wells has decreased markedly because of concernsaboutthe poorquality ofwaterdraininginto the aquifers. Attempts by the water management districts to locate these wells to help in water management planning have been hindered by the age of many of themand by poor recordsof theirexistence. At the time of this writing the USGS is preparing a map of known drainage wells (Kimrey, in prep). It is unlikely that most of the drainage wells in the Panhandle and in the State will be located. (3) Pressure injection wells are used invarious locationsthroughout the State as a meansol wastewater and storm-water disposal. These techniques, when used with storm water and with appropriate caution towards their potential for ground-water contamination, may help recharge the aquifer with water that would otherwise evaporate or run off. Pressure injection wells are of two primary types, those injecting into the fresh-water aquifers and those injecting into the saline-water aquifers. Injection into many potable water zones yields little increase in storage since the artesian aquifers are already full, sothis type of injection well is little used. Liquid wastes are being injected into saline waters in the deeperzones of the Floridan Aquifer as a storage and disposal method. There is evidence that this use is expanding, especially in storing or disposing of secondarily treated sewage effluent (Hickey 1984). The USGS has mapped the general locations of deep saline aquifers that might be suitable for liquid waste disposal (M~ller 1979). waste water is also injected into nonpotable areasof saline intrusion to create a back pressure and slow further intrusion (Stewart 1980). Because of concern over the long-term effects of this practice, the USGS is involved in extensive investigations into this practice (e.g., Kaufman 1973; Pascale 1976; Pascale and Martin 1978; Ehrlich et al. 1979; Hull and Martin 1982; Vecchioli et al., in press; Merritt, in press) and chemical changes in the wastes following injection. Temporary storage of freshwater (storm water) in saline aquifers is being evaluated by the USGS in south Florida. (4) The surface hydrology of aquifer recharge areas selves to channel water to or away from recharge areas (Figure 40). Recharge through sinkholes and other breaches of the confining layer, and by percolation through porous soils can be easily altered by human activities. Wetlands may serve to hold water over areas of low porosity, thereby increasing the amount of water percolating to the aquifer. Diversion of surface drainage to, or away from, sinkholes and wetlands, as well as speeding surface drainage away from recharge areas as a flood prevention measure, affects the amount and quality of water recharging the aquifer. Development activities, especially in recharge areas, must be performed carefully to ensure protection of ground-water supplies. 4.4.2 Major Influences on Ground-water Quality a. Natural factors affecting ground-water quality. Many areas in the Panhandle function as recharge areas for the Floridan Aquifer (Figure 40), and the Floridan Aquifer, being unconfined in much of the Panhandle, is recharged throughout most of the area where it exists. There is often a general perception that surface water contacts ground water only after it has very slowly percolated through purifying layers of soil and rock. In Florida, includingthe Panhandle, this perception is generally incorrect. In many ground-water recharge areas, the surface bodies of water and surface runoff are directly connected to the ground water by channels through the intervening rock. Below the surface of the land, Florida is largely a sponge of karstic limestone penetrated by innumerable solution channels and sand beds. Though these porous layers of limestone are oflen separated by confining layers of clay and rock, their connections to the surface and to surface waters is evident in the numerous springs and sinkholes which dot Florida's landscape. Many sinkholes act as drainage gutters, providing direct contact between contaminated or uncontaminated Surface runofl and the ground-water aquifers. The Sand and Gravel aquifer is just a layer of fine-tocoarse quartz sand sometimes mixed with small quartz or chert gravel (Hyde 1975) lying on top of a confining iayerand exposed at the ground's surface.
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Panhandle Ecologlcal Characterizatlon Percolation of surface waters into this aquifer is fast and relatively unobstructed. Ground water from the Floridan Aquifer is characterized by high pH, alkalinity, and hardness. This results fmm contact with the limestone within which the Floridan is found. Water from the Sand and Gravel Aquifer is acidic and has low concentrations of dissolved solids. The normal ground water characteristics in the shallower aquifers are affected by surface water hydrology. During periods of high surface water, substantial quantities of often dark. acidic swamp runoff find theirway into and mix with (or replace) the ground water, rendering the quality of water from shallow wells similar to that of the surface waters. b. Anthropogenic factors affectlng groundwater quality. Anthropogenic effects on groundwater quality takes three forms: (1) contamination via surface waters and leaching of surface contaminants; (2) contamination via direct means, i.e., drainage wells and injection wells; and (3) increasing intrusion of saline waters into potable aquifers through excessive pumping of ground waters. (1) The Surficial Aquifer, the Sand and Gravel Aquifer, and the Floridan where it is unconfined (not covered by a stratum of low permeability) are often at or near the surface and are by their proximity easily contaminated. Even where beds of low permeability overlie the aquifer (Figure 50), surface contaminants are relatively easily introduced. The terms "confining beds" and "low permeability" were drafted by hydrologists describing the movement of ground water. For purposes of water consumption. an overlying or surrounding stratum of low permeability may slow local ground-water recharge sufficiently to prevent large withdrawals of water from an area. Percolation rates measured in inches per day are very slow in terms of aquifer recharge, but all too fast in terms of movement of contaminants toward potable aquifers. (2) Drainage wells have been in use for some time, sometimes for the disposal of sewage and other effluents, usually for the disposal of unwanted surface water. Concerns have been raised over the possible health effects of such activities, and their use is being actively discouraged. Injection wells are relatively new and, as is discussed in 4.4.l(b), their effects are being studied intensively by the USGS and they are heavily regulated by the U.S. Environmental Protection Agency (EPA) and the FDER. (3) Salt water intrusion is becoming an increasing problem, especially in coastal areas. Wiihdrawal of excessive volumes of ground water increases intrusion of saline waters, as discussed in 4.4.l(b). One aspect of this that is often overlooked is that intrusion of saline waters into the shallow ground waters along the coasts (where the potable aquifers are thinnest) can change the makeup of overlying vegetation by killing species that are not salt tolerant. 4.5 Area-wide Surface-water Hydrology and Water Quality The seven major Panhandle coastal rivers originate in Georgia or Alabama. Changing land use in these States, as well as in the Panhandle, is directly affecting the rivers' hydrology and water quality (FDER 1986~). There has been some successful cooperation among the States in investigating the interstate drainage basins (e.g., U.S. DeptofAglture 1977). but less in instituting interstate corrections to problems. Table 3 gives major drainage basin and waterbody sizes as well as streamflows for Panhandle lakes and rivers. Foose (1 980) givesdrainage basin, river, and lake areas for Florida including the Panhandle. His laterwork (Foose 1983) includesfurlher statistics concerning flow characteristics of Florida rivers The Northwest Florida Water Management District (NWFWMD) has published reports on the flood damage potential of the district (NWFWMD 1977); on the availability of water for industrial uses within the district (NWFWMD 1980a); on the availability of water resources in the peninsula area of southem Santa Rosa County (NWFWMD 1979b) and southern Okaloosa and Walton Counties (Barr et al. 1981); summarizing available rainfall data for the Panhandle (Kennedy 1982); and an exhaustive statistical summary and inventory of Panhandle lakes and streams which should answer most questions concerning hydrologic regimes and the frequency with which a given hydrologic condition occurs (Maristany et al. 1984).
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Panhandle Ecological Characterization
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Panhandle Ecological Characterization temperatures near 10 "C in winter and maximum temperatures near 30 "C in summer. Shallow sheltered embayments and other areas with minimal mixing with offshore waters may, however, have greater temperature ranges than these. The FDER ranked Florida lakes, based primarily upon their trophic state, in an effon to objectively determine those most in need of restoration and those most in need of preservation (Myers and Edmiston 1983). This ranking was based largely upon a report by the University of Florida, Department of Environmental Engineering Sciences (1983). Results penaining to the Panhandle drainage basins are included in the following sections; however, since this ranking was performed on lakes where prior studies provided sufficient data, and since public interest was afactorweighed in assigning rank, it is not adefinitive statement of the relative conditions of all lakes in Florida. 4.6 Area-wide Ground-water Hydrology and Water Quality Ground water within the Florida Panhandle is influenced by the hydrology and water quality of the overlying surfacewater; however, the flow of ground water is little affected by the flow constraints of the overlying drainage basins. Asa resultthediscussion of some aspect of ground water often includes factors from more than one drainage basin. Although ground water is discussed in the following drainage basin sections, each discussion is largely restricted to the effects of the surface waters in that particular basin upon the ground water. Studies looking at the aquifers on a larger scale and across more than one drainage basin are covered in this section. The Floridan Aquifer contains most of the nonsaline ground water in the eastern portion of the Panhandle and is the primary potable water source in this area. Beginning in Okaloosa County and continuing westward, the Floridan is located deeper and its water becomes highly mineralized: therefore thesand andGravel Aquiferis morecommonly used in these areas (Figure 37). The approximate thickness of the potable-water zone in the Floridan is shown in a USGS map (Causey and Leve 1976). Pans of Bay County use Deer Point Lake as a water source since the Floridan in that area has relatively low transmissibility and does not support large well fields (U.S. Army Corps of Engineers 1980a). The Surficial Aquiferconsists of a porous, sandy surface layer recharged locally and is separated from the underlying Floridan Aquifer by a clay-containing layerof lowpermeability-aconfining layeror aquitard. The Surficial Aquifer varies in thickness and, where the underlying Floridan or the confining layer are at the surface, may not exist at all. To the west the Sutlicial Aquifer thickens and deepens and becomes the Sand and Gravel Aquifer (Figure 38). Additional small but usable quantities of water exist in some areaswithin the clay and sandy-clay confining layer separating the aquifers; however, except in ~ral areas with small requirements, these are little used because of the larger volumes available in the major aquifers. Because of the occurrence of this ground water within the confining layer, it is sometimes called the Intermediate Aquifer. Its primary action, however, isto restrict the movement between the Surficial or Sand and Gravel Aquifers and the underlying Floridan Aquifer. The average temperature of the top 25 m of ground water in the Panhandle range is approximately 21 "C, varying ab0ut4~Cthroughoutthe year (Heath 1983). The shallow aquifers vary more than the deeper ones. The USGS has conducted numerous investigationsof the water resourcesof the Panhandle (Table 4). These include an examination of ground-water levels and water quality along the coast from Walton to Escambia Counties (Barraclough and Marsh 1962) and a later more detailed look at the water resources of WaRon County (Pascale 1974). Both the Sand and Gravel Aquifer and the Floridan Aquifer are important in this county, with the Sand and Gravel storing water for stream baseflow and recharging the underlying Floridan. The Sand and Gravel is also used as a rural water supply. The Floridan is the primary water supply in the county. Transmissivity within the aquifer is highly variable. The Floridan is exposed in Alabama north of the Walton County where it is recharged by rainfall. Ground water within the Floridan moves south, discharging by springs and seeps along the Choctawhatchee River and by leakage to Choctawhatchee Bay and the gulf.
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4. Hydrology and Water QualRy Table 4. U.S. Geologlcal Survey Maps for the Florlda Panhandle Surfacewater Hvdrologv 1. Runoff from hydrologic units in Florida (Hughes undated). 2. Runoff in Florida (Kenner 1966). 3. Annual and seasonal rainfall in Florida (Hughes et al. 1971). 4. Surface water features of Florida (Snell and Kenner 1974). 5. Water-level fluctuations of lakes in Florida (Hughes 1974). 6. Low streamflow in Florida-magnitude and frequency (Stone 1974). 7. Seasonal variation in streamflow in Florida (Kenner 1975). 8. The difference between rainfall and potential evaporation in Florida (Visher and Hughes 1975). 9. Average flow of major streams in Florida (Kenner et al 1975). 10. An index to springs of Florida (Rosenau and Faulkner 1975). 11. River basin and hydrologic unit map of Florida (Conover and Leach 1975). 12. Florida: Satellite image mosaic (U.S. Geological Survey 1978). 13. Long-ten streamflow stations in Florida, 1980 (Foose and Sohm 1983). 14. Hurricane Frederic tidal floods of September 12-13,1979 along the Gulf coast, Oriole Beach, Garcon Point, Holley, south of Holley, and Navarre quadrangles, Florida (Franklin and Bohman 1980). 15. Hurricane Frederic tidal floods of September 12-13. 1979 along the Gulf coast, Gulf BreezeFort Barrancas quadrangles, Florida (Franklin and Scott 1980). 16. Hurricane Frederic tidal floods of September 12-13,1979 along the Gulf coast, Perdido Bay quadrangle, Florida (Scott and Franklin 1980). 17. Wetlands in Florida (Hampson 1984). 18. Sinkhole type and development in Florida (Sinclair and Stewart 1985). 1. The pH of water in Florida streams and canal 6. Generalized distribution and concentration of (Kaufman 1975a). orthophosphate in Florida streams (Kaufman 2. Specific conductance of water in Florida streams 1975d). and canals (Slack and Kaufman 1975). 7. Temperature of Florida streams (Anderson 3. Dissolved solids in water from the upper pan of 1975). the Floridan aquifer in Florida (Shampine 1975a). 8 Nitrogen loads and concentrations in Florida 4. The chemical type of water in Florida streams streams (Slack and Goolsby 1976). (Kaufman 1975b). 9. Dissolved-solids concentrations and loads in 5. Color of water in Florida streams and canals Florida surface waters (Dysart and Goolsby (Kaufman 1975~). 1977). Ground-water Hvdroloav 1. Top of the Floridan artesian aquifer (Vernon 4. Principal aquifers in Florida (Hyde 1975). 1973). 5. Estimated yield of fresh-water wells in Florida 2. The ~bse~ati~n-~ell network of the U.S. Geolo(Pascale 1975). gical Survey in Florida (Healy 1974). 6. Potentiometric surface of the Floridan aquifer in 3. Piezometric surface and areasof artesianflow of the Northwest Florida Water Management Disthe Floridan aquifer in Florida. July 6-17, 1961 trict, May 1976 (Rosenau and Meadows 1977). (Healy 1975). (continued)
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Panhandle Ecological Characterlzatlon Table 4. Concluded Ground-water Hvdroloav tconcluded) 7. Potential subsurface zones for liquid-waste sto10. Potentiometric surface of the Floridan aquifer in rage in Florida (Miller 1979). the Northwest Florida Water Management Dis8. Areasof natural rechargetothe Floridanaquifer trict, May 1980 (Rosenau and Milner 1981). in Florida (Stewart 1980). 11. Potentiometric surface of the Floridan aquifer in 9. Estimatedpumpagefromground-watersources Florida, May 1980 (Healy 1982). for public supply and rural domestic use in Florida, 1977 (Healy 1981). Ground-water Chemistry 1. Quality of water from the Floridan aquifer in the 6. Depth to base of potable water in the Floridan EconfinaCreek basin area, Florida, 1962. (Toler aquifer (Klein 1975). and Shampine 1965). 7 Thickness of the potable-waterzone in the Flor2. Fluoride content of water from the Floridan idan aquifer (Causey and Leve 1976). aquiferof northwest Florida, 1963. (Toler 1965). 8. Chemical quality of water used for munlclpal 3. Chloride concentration in water from the upper supply in Florida, 1975 (Phelps 1978a). part of the Floridan aquifer in Florida (Shampine 9. Quality of untreated water for public drinking 1975b). supplies in Florldawith reference tothe National 4. Hardness of water from the upper part of the Primary Drinking Water Regulations (Hull and Floridan aquifer in Florida (Shampine 1975~). Irwin 1979). 5. Sulfate concentration in water from the upper part of the Floridan aquifer in Florida (Shampine 1975d). Water Use 1. Estimated water use in Florida, 1965 (Pride 5 Consumptive use of freshwater in Florida, 1975). 1980 (Leach 1982b). 2. Principal uses of freshwater in Florida, 1975 6. Estimated irrigation water use in Florida, 1980 (Phelps 1978b). (Spechler 1983). 3. Freshwater use in Florida, 1975 (Leach 1978). 7. Projected public supply and wral (self4. Estimated water use in Florida, 1980 (Leach supplied) water use in Florida through year 1982a). 2020 (Leach 1984). The USGS alsocarriedoutsimilar investigations of water resources in Okaloosa County in a study which included portions of western Walton County (Trapp et al. 1977). This study was prompted by the declining level of the upper Floridan Aquifer within the area. This area depends almost entirely upon thisaquiferforitswatersupply. Thestudyconcluded that levels would continue todecline until wells were betterdistributed, and alternate water sources, such as the Sand and Gravel Aquifer or surface waters, were placed into operation. This report includes a good description of the drainage conditions throughout the region. These conditions vary widely because a number of different physiographic regions and soil types are found within the area. These USGS studies on the western Panhandle were updated by later publication of a hydrologic budget for Escambia County (Trapp 1978), of hydrologic and water quality data for Okaloosa, Walton,
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4. Hydrology and Water Quallty and southeastern Santa Rosa Counties (Wagner et al. 1980) and in a study of the hydrology of the coast of Okaloosa and Walton Counties (Barr et al. 1985). The USGS has produced many maps depicting ground-water hydrology and water quality in the Panhandle. These are listed in Table 4. In addition to the USGS studies, the NWFWMD has performed ground-waterstudiesof the quality and availability of waterfromlhe Sand and Gravel Aquifer in southern SantaRosaCounty (Pratt andBarr 1982), the hydrogeology of the Sand and Gravel Aquifer in southern Escambia County (Wilkins et al. 1985), and the hydrogeologic effects of solid-waste landfills in northwest Florida (Bartel and Barksdale 1985). The NWFWMD has also compiled a ground-water bibliography with geological references for the district (Wagner 1985). The lack of separation between surface and ground water in most of the Panhandle, especially in those areas where springs abound, cannot be over emphasized. The direct connections can easily be verified by observing local wells and springs during moderate to high waterperiods. At these times, well waters and springs are often brown from the tannic acid of surlace waters, and some springs can be seen to be acting as siphons, draining surface waters to the underlying aquifer (Figure 49). Within the Panhandle, ground-water pumping has lowered the potentiometric surface of the Floridan Aquifer significantly only in coastal Okaloosa County (Figure 52). In this region, the surface of the aquifer declined approximately 27 m between 1940 and 1961 (Barraclough and Marsh 1962) and another 12 m between 1961 and 1972 (Healy 1982). This permitted saltwater intrusion and contamination of area water supplies. Relocation of wells farther inland and other measures reducing the withdrawal of ground water have resulted in a partial rise in the surlace of the aquifer in this area. However, water levels in 1980 were still as much as 33.5 m below 1940 levels (Wagner et al. 1984). Ground-water pumping for irrigation in southwest Georgia increased 500% between 1973 and 1980 (U.S. EPA 1983); this withdrawal has been documented as affecting nearby wells and surface waterflow, including that of Panhandle rivers with basins in that area (FDER 1986C). Ensuring continuing water supplies requires regulation by governmental authorities because the hydrology and water quality of Panhandle ground waters are wide-reaching phenomena which do not respect private boundaries. We encourage the continuing public purchase of major ground-water recharge areas as the best long-term solution to maximizing recharge while protecting water quality. 4.7 Basin Hydrology and Water Quality 4.7.1 Ochlockonee River Basin (Figure 53) The Ochlockonee River and its numerous tributaries drain approximately 5,830 km2, of which 52% (3,030 km2) is in Georgia and 48% (2,800 km2) in Florida (Foose 1980). Within Florida. the Ochlockonee River basin cuts through two physiographic divisions, the redclay of the Tallahassee Red Hills in the norlhandthesandy Gulf Coastal Lowlands in the south (Pun and Vernon 1964). The Ochlockonee and its major Florida tributary, the Sopchoppy, have been designated Outstanding Florida Waters (OFW--no significant degradation permitted). Approximately 105 km down the river's 180-km course through Florida, the Jackson Bluff Dam backs the river up to form Lake Talquin. This dam was operated as a hydroelectric generation plant from 1930 to 1970 and was reactivated in 1985. The operation of the powerplant turbines can cause substantial drops in lake level over short periods of time; as a result their use is being limited to that producing drops of less than 1 it below normal (nongenerating) levels. Lake Talquin is listed by Myers and Edmiston (1983) as one of the top 50 lakes in the State needing preservation and piotection. The river drops about 27 m from the Georgia border to the coast (Pascale and Wagner 1982). Above the dam the river is characterized by sharp bends and low banks with an average fall of 0.14 rnl km. Below the dam the river widens and passes through wide bottomlands and marshes, becoming tidal 19 krn from the mouth. Much of the river basin below the dam (about 910 km2) is contained in the Apalachicola National Forest and aportion (about 65 km2) near the mouth is in the St. Marks National Wildlife Refuge.
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POTENTIOMETRIC SURFACE VALUES POTENTIOMETRIC SURFACE VALUES
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Panhandle Ecologlcal Characterlzatlon East of the river nearthe Florida-Georgia border lie two large lakes whose water level is loosely affected by ground-water levels (Sellards 1917. Hendry and Sproull966) Lake lamonia and Lake Jackson were formed by the the coalescence of sinkholes caused by solution and collapse of the area limestone (Hutchinson 1957). The lakes are poorly connected to the Floridan Aquifer through numerous completely or partially plugged sinkholes in their lake beds. Lake levels normally are 11-14 m above the potentiometric surface of the Floridan Aquifer (Pascale and Wagner 1982) and, as a result, leak to the aquifer, thereby recharging it They sometimes drain completely following extended dry spells when the aquiter has dropped several feet. Lacking the ground water's support of the overlying limestone and sediments, either sinkholes form as the lake bed collapses into the now air-filledcavities, or the sediment plugs which block pre-existing sinkholes collapse. The remaining lake water may then rushWdown thedrainWoverafew daysorweeks. The last two occurrences in Lake lamonia were in 1931 and 1981 :the lasttwo in Lake Jackson were in 1956 and 1982. The lakes refill when the water table returnsto normal levels, and the sinkholes eventually plug with new sediments. The hydrologic significance of flooding in Lake Jackson during 1960 was reported on by the USGS (Hughes 1969). A hydrologic assessment of the 1982 draining was performed by the NWFWMD (Wagner 1984). Until recently Lake lamonia was connected to the Ochlockonee River by a natural channel which allowed river flood waters to flow to the lake and lake flood waters to flow to the rivets flood plain. A structure was buiii to regulate thls flow in 1976 (Pascale and Wagner 1982). Since 1977 efforts have been underway to drain the lake through a sink located on the north shore in an effort to control the growth of aquatic vegetation. A hydrologic assessment of the lake and the sink was performed by the NWFWMD (Wagner and Musgrove 1983). The Lake Jackson basin has been increasingly developed with the resulting sediment and nutrient input accelerating eutrophication and degrading the lake's water quality and habitat (Babcock and Rousseau 1978). Harris and Turner (1974) studied the lake's water quality and characterized the northern sections of the lake from good to excellent while the southern sections, including Megginnis Arm, Ford's Arm, and a small part of the open lake, were tairto poor and highly variable. Following Harris and Turner's study, the water quality was monitored by the FloridaGame and Fresh Water FishCommission (Babcock 1977) and then by the FDER. Algalassays were performed by FDER on twooccasions to determine the nutrients limiting algal growth in Megginnis and Ford's Arms and in the northern mid-lake (FDER 1980). Theyfoundthat, atthetimesof sampling, the water of Megginnis Arm was primarily phosphate limited and secondarily nitrogen limited. The water in Ford's arm and the mid-lake norfh station were nitrogen and phosphate colimited. In all instances the growth was below that expected. This was tentatively attributed to the phosphate available for biological uptake being less than the orthophosphate concentrations found by chemical analysis. In an effort to slow this degradation, a number of local, State, and Federal agencies cooperated in the installation in 1984 of a stormwater retention and treatment facility using some relatively untried methods (NWFWMD 1984). The facility's use of retention ponds and aquatic p!ants for sediment and nutrient removal is still being evaluated and adjustments are still being made, but initial results show improved water quality in the water being discharged to Megginnis Arm (Tuovila et al. in press). However, substantial improvement in the overall waterquality of the arm has not beendemonstrated, possibly because of the release of nutrients bound up in lake bottom sediments. West of the river and away from the coasts, surface runoff forms myriad tributary streams. Many of these, including Little River, Bear Creek, and Ocklawaha Creek, drain into LakeTalquin. The land east of the river in this area is a porous karstic limestone that provides a quick path for rainfall to recharge the aquifer. As a result, the familiar dendritic pattern of stream runoff is absent. The ground and surface water resources of the Little River basin have been examined by the NWFWMD (Wagner 1982, Maristany 1983). The Ochlockonee River receives very little ground water contribution in its upper reaches (Pascale and Wagner 1982), thus its flow is dependent on rainfall patterns and is highly variable. Ochlockonee Bay and possibly the lower river
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4. Hydrology an d Water Quallty receive ground-water flow as the rocks of the Floridan Aquifer outcrop and the aquifer potentiometric surface isabove thesurfaceofthe river. Cray's Rise. on the north shore of Ochlockonee Bay, is an example of aquifer discharge. Bradwell Bay, a large marsh east of the river's lower reaches, has formed because of poor soil permeability and lack of a sufficient relief to promote drainage. The Sopchoppy River flows alongside and east of the lower Ochlockonee River into the Ochlockonee Bay estuary. The Sopchoppy River is often considered a tributary of the Ochlockonee River (NWFWMD 1979); however, the USGS feels that the flows are sufficiently separated to merit listing them as independent rivers (Pascale and Wagner 1982). Hand and Jackman (1 984) reported naturally low pH levels in several of the basin tributaries, particularly the Sopchoppy River, caused by the swampy drainage lands. Hydrologic, geologic, and water quality data tor the Ochlockonee River basin was compiled by Pascale et al. (1 978). The USGS reported on severe flooding in Gadsden County during 1969 (Bridges and Davis 1972). The water quality of the upper river has been deteriorating in recent years (Hand and Jackman 1984, FDER 1986a). Forestry and agriculture are the predominant land uses in the basin; however, fuller's earth (clay) is mined in Georgia and Florida near the border and sedimentation from the mining has reduced benthic community diversities in the upper section of the river. Bacteria and nutrients from point sources in Georgia have historically damaged the qualily of the river water entering Florida. In Florida, Attapulgus and Willacoochee Creeks are the majorcontributors of sediment-laden waterto the Ochlockonee (FDER 1986~). The Liitle River and its upstream tributary Quincy Creek have historically shown bacteria, nutrient, and turbidity problems from upstream sources including the City of Quincy Sewage Treatment Plant and Fuller's earth mining at the Floridan strip mine (Hand and Jackman 1984). Additionally, below the GeorgiaFlorida border the river water quality has historically bacteria and nutrient concentrations and low macroinvertebrate diversity continue to be problems. The water quality of the Ochlockonee River improves downstream from this area. Hand and Jackman (1 984) and FDER (1 986a) attributed these problems to Georgia point sources. According to Georgia's 1982 305(b) report (reporting status of the State's water quality to EPA) these problems should decrease because of treatment plant upgrading. Five stations within the basin were examined during 1973-78 for biological indications of water quality (Ross and Jones 1979). A station in the Ochlockonee River near the Georgia border was sampled only a few times. Macroinvertebrate species diversities appeared high, though Biotic Index values suggestedthe possibility of problemswith low dissolved oxygen during summer low flow. At a station below the Talquin Dam, too few macroinvertebrate samples were taken to make judgments, but bacteria counts were occasionally high, probably from runoff. A station in Lake Jackson appeared to improve during the study period; however, nutrient and silt inputs from urban and residential runoff had degraded apparent water quality and contributed to nuisance growth of aquatic weeds. A station in the Sopchoppy River at SR 375 was in an area primarily of swamp drainage; macroinvertebrate diversity was high from the three samples taken. The final station in Ochlockonee Bay west of Bald Point had consistently high macroinvertebrate diversity. The water resources in the area from Quincy in Gadsden County southeast to the Ochlockonee River above Lake Talquin have been studied fortheir ability to support industry (NWFWMD 1980a). This study showed that the water quality of the Surficial and Intermediate Aquifers is generally good, but bacterial levels in the Surficial Aquifer, caused by its proximity to the surface, require that the water be treated before use. The Surficial Aquifer inthis basin is presently important primarily for its water storage capacity (approximately 1.25x109 m3), its maintenanceof streamflow. and itsrecharoe of the lntermehad DO, bacteria, nutrient, and turbidity problems. diate and Floridan Aquifers (pascale and Wagner Twenty-three major permined point source dis1982). The Intermediate Aquifer (which is also chargers operate in the basin. Thirteenof these are known as the water bearing zone of the upper sewage-treatment plants (eight in Georgia and five confining unit of the Floridan) in the northern basin in Florida) and ten are industrial dischargers. High consists of a low-permeability layer of sandy clay
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Panhandle Ecological Characterization and sandy limestone of variable thickness (from Oto Sound at the town of Carrabelle. The western a maximumof about 60 rn in the Greensboro-Quincy portion is Tate's Hell Swamp, a large, densely area) confined above and below by layers of clay. wooded and vegetated swamp which drains to East The extent of this aquifer diminishes southward Bay in Apalachicola Bay. Whiskey George Creek is throughGadsdenCounty andisdiscontinuoussouth the stream within Tate's Hell with significant flow to of Lake Talquin. These shallow aquifers are suitable East Bay. only for very small demands. The &ay layerseparating the Intermediate Aquifer from the Floridan is approximately 6 m thick in Gadsden County (NWFWMD 1980a). The Floridan at tnis location is of relatively low porosity and is recharged locally by leakage through the confining layer. The low rate of recharge allowed by theconfining layer has prevented thorough flushing of the Floridan locally, and residual sea water from the last period during which the area was below sea level is still present at relatively shallow depths within the aquifer. The water quality of this aquifer is acceptable, with the concentration of dissolved solids increasing rapidly with depth. Wells tapping the Floridan yield as little as 75 Ilmin in Gadsden County to as much as 17,000 limin in Leon County. The USGS has mapped the flood-prone areas (i.e., those inundated by a 100-year flood) of GadsdenCounty (Rumeniket al. 1975). Aswouldbe expected most of these areas are along the rivers and streams of the county; however, numerous spots are unattached to these drainageways. Ground-water pumping tor the town of Panacea from two wells drilled in 1965 resulted in saltwater intrusion by 1970. Subsequent investigation by the USGS determined that the aquiferdischarges to the bay and river, and that the upward movement of The construction within the swamp during the early 1970'sof logging roads and drainage ditches to direct surface water to the Apalachicola River is reported to have altered the drainage patterns sufficiently to result in dry areas, substantially altering wildlife habitat and increasing fire hazard (Bruce Means, Coastal Plains Institute, pers. comm.). The major causes of water quality problems in this basin are the discharges to the coast from the sewage treatment plants in Carabelle and Eastpoint and surface runoff from forest clearcutting by Buckeye Cellulose Corporation. The City of Eastpoint Water and Sewage District Waste and Treatment Facility is being upgraded and the system expanded to replace many of the septic tanks in the area. The City of Carabelle WastewaterTreatment Plant isthe only plant in northwest Floridaprovidingonly primary treatment (Florida Rivers Study Committee 1985). The highly chlorinated sewage which is discharged degrades the water in the vicinity of the outfall to St. George Sound and settles10 form putrescent sludge deposits. Overly enriched waters produce plankton blooms and excessive growth of filamentous algae, bacteria, viruses, and fungi that are pathogenic to the sea grasses of St. George Sound. This plant has been under some form of enforcement action for years. aquifer flow in the area tends to bring deeper salty ~h~ effects of runoff from forest clearcutting water into the upper zone of the aquifer (Pascale and operations upon the New and Crooked Rivers was Wagner 1982). investigated by Hydroscience, Inc. (1977). They Ground-water movement in the northern pan calculated minimal long-term effects upon the rivers this basin tends to be towards the southeast west of and the bay into which they discharge, but fen that the river and to the south east of the river toward Short-term nutrient, turbid~ty, and color spikes could Wakulla Springs, km south of be a Problem. Their investigation was, however. aimed at effects in the rivers, and not at the effects Area between Ochlockonee and upon the wetland hydroiogy in the swamps. The Apalachlcola Rivers (Figure 53) purposeful draining of the wetlands to ease timber harvesting was the source of changes documented This 1,440 km2 area is poorly drained and conbv their studv. sists of two main regions. The eastern portion of the -2 ---, basin (830 km2) isthe area drained by the New River This basin has been studied very little. No staand its tributaries, which discharge into St. George tions examining the biological indications of water
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4. Hydrology and Water Quallty quality were located in this basin during the period analyzed by Ross and Jones (1979). 4.7.3 Apalachlcola Rlver Basin (Figure 53) The Apalachicola Riveristhe21 st largest river in flow in the conterminous United States and is by far the best studied river system in the Panhandle. The Apalachicola, together with as main out-of-State tributaries, the Chattahoochee and Flint Rivers (together often called the A-C-F basin) and its main in-state tributary, the Chipola River (separately addressed in 4.7.4), drains approximately 51,000 kmzof Georgia, Alabama, and Florida. Of this basin only 13% (-6,500 km2) is in Florida, and the Florida portion, excluding the Chipola River basin, is less than 8% (-3,830 kmz) of thetotal. The majorlty of the remaining 44,500 km2 consists of Georgia's Flint River watershed, which drains into Lake Seminole on the Georgia-Florida border. River flow normally variesfrom 250 to 2.800 m3/s (FDER 1984a) and the mean flow from 1958 to 1980 was 690 m3/s (Leitman et al. 1983). The river width at mean discharge varies from 75 to 300 m (FDER 1984a). Seasonal river stage fluctuations are 3 times greater in the upper river than in the lower and peak floods are most likely to occur during January through April (Leitman et al. 1983). Low flows are usually found duringseptemberthrough November. Georgiarainfall has much greater influence on flow in the upper Apalachicola than does Florida rainfall. Georgia rainfall is slightly higher in winter and much lower in summer than is Florida rainfall. Both experience similar quantities of rain in spring and minima in October-November. When the Apalachicola is high the Chattahoochee River contributes most of the flow as it is steeper than the Flint River and has abundant rainfall in its upper basin. This results in large pulses in the Chattahoochee contribution. The Flint River basin isflatter and receives muchspringflow, providing a more stable flow regime. During low flow conditions in the Apalachicola, these two tributaries contribute more equal flow. During extreme low flow the Flint is the major contributor (Leitman et al. 1984). The Chattahoocheecontribution is becoming more stable because of the Army Corps of Engineers'dams and flow regulation. During the next 20 to 30 years growth of the Atlanta area and the resuling increased use of the Chattahoochee River asa water supply could reduce thevolume of its wntribution to the Apalachicola River and Bay (Livingston 1983). This has the potential to seriously alter the salinity regime within the bay, thus reducing the fisheries potential. The Apalachicola River discharge peaks in winter and early spring anddeclines untilfall (Figures45 &46). The averagewinter-early spring flow is 2 to 3 times the average summer flow. The Florida basin rainfall averages 147 cm while the mean annual potential evaporation is 99-114 cm (U.S. Dept. Agriculture 1969). From Chattahoochee to Blountstown the river has long straight stretches and gentle bends. This part of the basin is chacacterized on the east side by steep bluffs backed by relatively high and ~gged terrain. Small tributary streams have incised deep channels producing the most hilly areaof Florida. On the west side the basin consists of gently rolling, lower land containing a 1.5-3 km wide flood plain (Leitman et al. 1983). Ocheesee Pond, west of the river in Jackson County, is the largest natural lake in the area. From Blountstown to Wewahiichka the river channel meanders with large loops and many small tight bends to the south, and the flood plain is 3-4.5 km wide. Below Wewahitchka the river has long straight stretches with a few small bends and the flood plain widens to 4.5-8 km. A map of the Apalachicola River flood plain and data on the associated hydrologic conditions are presented in Leitman (1 984). At the Chipola Cutoff (just below Dead Lake), approximately 25% of the Apalachicola flow divens to the Chipola River (Ager et al. 1983). The Chipola River flow measured above the Chipola Cutoff averaged 10% of that of the Apalachicola River during 1979-80 at Sumatra (Leitman et al. 1983). A similar situation exists farther downstream where the Brickyard Cutoff diverts Apalachiwlaflowto near the head of the Brothers River. This diversion involves sufficient quantities of water that the water chemistry of the Brothers River is controlled by that of the Apalachicola River (Ager et al. 1983). Lake Wimico is located in the southern part of the basin west of the Apalachicola and receives wnoff from numerous streams draining the southwestern ponion of the Apalachicola River Basin. From here the water flows 5.5 km via the Jackson
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Panhandle Ecologlcal Characterlzatlon Rivertothe ApalachicolaRiver, near its mouth. Lake Wimico is one of the 50 lakes in the State listed in Myers and Edmiston (1983) as most in need of preservation and protection. Land use in the basin is diverse and includes agriculture, forestly, and manufacturing. The basin hydrology has been substantially altered by dredging, spoil disposal, and construction of navigational aids. The Corps of Engineers const~cted four cutoffs in 1956-57 and three more in 1968-69, straightening oxbow river bends to ease barge traffic These cutoffs have shortened the river by 3 km. About 765,000 m3/yr are dredged from the river and placed in and along the river in an effort to maintain the Federally authorized 9 ft by 100 ft channel (Eichholz etal. 1979). Effectsonwaterquality within the river were felt for only a short distance below the dredging activity and impacts were minor because the dredging usually takes place in areas with unstable bonomsand hence low productivity. Additionally, much of the dredged material is medium to coarse sand, the suspension of which produces little and shorl lived turbidity (Leitman et al. 1984). The Corps of Engineers reported that turbidity in the dredging plumes dropped to ambient within 18 m of the discharge pipe. Dredge material disposal sites along the lower river have been studied to assess their effects (Eichholz et al. 1979, Leitman et al. 1984). Army Corps of Engineers dredging of the river shipping channel has affected river and floodplain hydrology and biota. Effectsfromdredging extend into habitats beyond the river bed. Spoil deposited in floodplains adjacent to the river, in addltion to killing the trees and other plant growth within the spoil area, altered the hydrologic flow patterns in the floodplain and therefore, in some instances, the habltat. Eichholz et al. (1979) recommended spoil disposal between the river banks in areas where the bottom was unstable already and therefore low in productivity. Leitman et al. (1983) found that the river stage at Chattahoochee was lower than before channel alterations. Lake Seminole serves as a sediment trap and tends to adsorb metals and other potential pollutants from upriver and prevent their migration downriver. It is estimated that Lake Seminoletraps 65%-70%of the sediment flowing into it. Heavy metals in dredged sediments were low except for iron, which was primarily in an insoluble form (Leitman et al. 1984). Pesticides in the sediments were generally below detection levels and those detectebArchlor 1254 (a DDT breakdown product) and 2-4 Lwere in the upper river. The bedof the Apalachicola River is undergoing degradation, whereby it erodes away, lowering its elevation and exposing bedrock outcroppings. The rate of this process in the upper river has been increased by the construction of the Jim Woodruff Dam(Leitmanetal.1984). Thestateof Florida, after many conflicts over the A-C-F basin with Alabama and Georgia, entered into a Memorandum of Agreement with thosestates in 1979tocooperate in a long range water budget and management plan. As part of the Agreement, required by the other States prior to their consenting to having Apalachicola Bay designated a National Estuarine Sanctuary, Florida promised to cooperate in efforts to increase the aviilability of a 9-ft channel, and subsequently gave the Corps of Engineers permission in 1984 to remove a numberof rockoutcroppings (USACE 1984). Removal of outcroppings, which slow river flow, destroys valuable fishery habitat (Eichholz et al. 1979). Before this work was completed the Corps suggested other areas for removal (Florida Rivers Study Committee 1985). Navigation projects in the Apalachicola are incrementally altering the river ecosystem. Each project since 1954 has been justified as maintaining the Federally permitted 9-ft deep channel. To date, little overall improvement has been noted. The 9-fl controlling depth is available an averageof 80%of the time and in 1981 (adry year) was available less than 10% of the time (Florida Rivers Study Committee 1985). It appears that thisdepthwillalso be availablevery little during 1986 following the record spring drought. It seems that during some portions of the year a 9-ft by 100-ft channel in the Apalachicola River requires agreater volume of water than the river can provide without sacrificing the rlver basin habitat, and that the goal of 95% availability of this depth is not realistic. Water resource projects (dams and other flowcontrol structures) are common. The Corps of Engineers has constructed and operates a network of five large dammed impoundments in the Chanahoochee River subbasin alone. Sixteen dams exist in the river basin, including those in Georgia and
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4. Hydrology ar ~d Water Quallty Alabama; the five largest influence seasonal, weekly, or daily flows: the other eleven have no effect on flow (Leitman et al. 1983). The southernmost dam in the Apalachicolawatershed, the Jim Woodruff Lock and Dam, which became operative in 1954, is located near the Florida-Georgia border and marks the beginning of the Apalachicola River. Lake Seminole, formed behind the dam, is located at the Florida-Georgia border and receives flow from the Chattahoochee and Flint Rivers. The dam was constmcted primarily to aid upstream navigation and to generate power, and secondarily to regulate streamflow and for recreation and conservation (Maristany 1981). Normal dam operations restrict lake level fluctuations to I ft. Maristany (1981) concluded that the dam has practically no flood control capability because its working storage is equal to approximately 1 day of average river flow. Additionally, it has limited use for low flow regulation because the working storage could only augment downstream riverflow by 10%of the average riverflowfor 10 days. He further concluded that the dam has exhibited practically no effect on annual mean flows. More detailed information on the Chattahoochee and Flint Rivers is available in a comprehensive report wmpiled by the States of Alabama, Georgia, and Florida in cooperation with the Mobile District of the Army Corps of Engineers (USACE 1984). The Florida Department of Administration (1977) prepared a report on the Apalachicola River and Bay System prior to the State's designating it an Area of Critical State Concern. This report examines the potential impacts of various basin alterations including additional dams and locks, channelization, and levees. The Florida portion of the Apalachicola River and Apalachicola Bay have been designated Outstanding Florida Waters (OFW); that portion below the northern Gulf County line since 1979 and that above it since 1985. The Florida Defenders of the Environment wrote a persuasive report describing the upper Apalachicola basin and nominating it for OFW status (Florida Defenders of the Environment 1982). One mileofthe 107 river miles in Floridawas not designated OFW because of preexisting industry: one-half mile adjoining the Jackson County Port Authority and one-half mile below SR 20 (FDER 1984a). The OFW designation was further altered10 exempt Army Corps of Engineers' maintenance of a shipping channel. The effects on the hydrology and ecology of the basin from the dredging and rock removal planned and carried out as part of this maintenance are discussed in Leitman et al. (1984). Following the Federal purchase of substantialquantities of surrounding lands, the lower river and Apalachicola Bay was named a National Estuarine Sanctuary. They have also been designated a State Aquatic Preserve and an International Biosphere Reserve. The head of the river basin is north of Atlanta in the Blue Ridge Mountains and parts of the Georgia and Alabama portions of the basin are urbanized. These areas include Gainesville, Atlanta, Columbus, Thomaston, and Albany in Georgia, and Phoenix City, Eufaula, and Dothan in Alabama. The Florida portion is sparsely populatedwith four population centers: Chattahoochee, Marianna, Blountstown, and Apalachicola. However, runoff from steep terrain in Chattahoochee, Sneads, Blountstown, and Bristol could be the source of future problems (FDER 1984a). Apalachicola Bay is dependent upon the transport of nutrients from the river's flood plain (Livingston 1981, Mattraw and Elder 1983). This transport takes place as bothdissolved nutrients anddetritus, withdetritusplayingthe most important role. The Jim Woodruff dam stops detrital transport from further upriver; therefore Apalachicola Bay depends upon its floodplain in Floridafor most of its nutrient input. The water flowing from Lake Seminole does not contain a substantial nutrient load, either dissolved orasdetritus (Elder and Cairns 1982). The height of natural river bank levees and the size and distribution of breaks in the levees have a major controlling effect on the floodplain hydrology (Leitman et al. 1983). Much of the lower river floodplain is permanently or semipermanently flooded; Leitman et al. (1983) and Leitman (1984) detail floodplain locations and descriptions. Nutrient and detritus transport in the Apalachicola River has been analyzed (Mattraw and Elder 1980, Elder and Mattraw 1982, Mattraw and Elder 1983). Annual floods cause appreciable surges in nutrient transport, especially asdetritus. lnan86dayflood in 1980theyfound that half of the annual outflow of organic carbon, nitrogen, and phosphorus, along with 60%of the annual detritus load, passed their sampling station closest to the bay. The total organic carbon outflow at this station was 50% greater than the inflow to the river
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Panhandle Ecological Characterization at Jim Woodruff Dam and 25% greater than the increase in streamflow. The nitrogen and phosphorus increases were proportional to the streamflow increase. On an areal basis, they found the Apalachicola basin to export greaterquantities of carbon and phosphorus than most watersheds. In an earlier study it was found that the Apalachicola floodplain produces dissolved nutrients at approximately the same rate itconsumesthem, butthat it isanexporter of detrital matter (Elder and Cairns 1982). The Apalachicola wetlands produce some net increases in organic carbon and phosphate transport, but no net change in nitrogen concentrations (Mattraw and Elder 1983). Elder and Cairns (1982) discuss in detail the quantities and nutrient makeup of the floodplain detritus. The FDER (1984a) concluded that "Significant alterations in the form or amount of substances which reach the [Apalachicola] estuary could influence productivity of the bay. Alterations which would block the transpon of detritus and nutrients out of the floodplain or which limit the variations in flow volume of the river could have negative impacts on Apalachicola Bay." Best et al. (1983) investigated the feasibility of using Apalachicola wetlands for wastewater recycling beginning in 1981. They investigated various aspects of the wetland ecology and attempted to model the system so as to enable calculation of the effects of wastewater effluents released into the wetlands. Little information has been gathered to address impacts of toxic substances or nonpoint-source pollutants. The Apalachicola River has been found by researchers from Florida State University to have higherconcentrationsof germaniumthan most of the rivers in the world (Froelich and Mortlock 1984). Little is known of germanium toxicology. The major source of germanium in water is coal-fly ash from upwind coal-burning powerplants (FDER 1984b). High nutrient levels in Lake Seminole have caused problems with eutrophication and resulted in excess growth of aquatic plants. This growth is controlled with herbicide applications, which contributes to waterquality degradation inthe lake. The U.S. Army Corpsof Engineers (1982) completed acomprehensive study of waterquality in Lake Seminole and part of the Apalachicola. Numerous Federaland Statepermlted point sources discharge into the Apalachicola, Chipola, and Flint Rivers and their tributaries. These include municipal sewage treatment plants. industrial and agricultural faciliiies,and nuclear and fossil-fueled powerplants. In addition, large agricultural areas contribute nonpoint-source discharges. Nutrient enriched water pumped from and running off of grazing lands resulted in MIK Ranches being the only nonpoint discharger in the basin which has been regulated by the FDER (Esry 1978. FDER 1984a). This drainage from the MIK canal system reducedvisibility inthe riveras measured by a secchi disk to 30-45 cm (USACE 1981). Streams with the greatest amount of degradation include Double Bayou, Clark Creek, Murphy Creek, and Scipio Creek. Agriculture within a drainage basin often contributes nutrients, coliform bacteria, sediments, and pesticides to the river system. The FDER established a nonregulatory nonpoint source management program for agricultural interests that is administered by the Florida Department of Agriculture and Consumer Services in cooperation with the U.S. Department of Agriculture and the Soil and Water Conservation Districts. While this program has been tairly successful in parts of Florida, the largest resistance to it has occurred in northwest Florida, including the Apalachicola watershed (Florida Rivers Study Committee 1985). Theeffects of silviculture in the basin upon the water quality and biota of Apalachicola Bay were investigated in a report to Buckeye Cellulose Corporation (Hydroscience, Inc. 1977). The primary problems detected by monitoring stations along the river are highfecalcoliform counts and low DO below sewage treatment plants and industrial discharges. Before entering Florida, Apalachicola River tributaries receive numerous dischargesfrom Atlanta and other urban areas, from textile mills, paper mills, sewage treatment plants, steam powerplants, a nuclear powerplant, and extensive agriculture areas of Alabama and Georgia (Hand and Jackman 1984). The USGS has examined the effects of flooding on the sources of pathogenic bacteria in the Apalachicola River and Estuary from 1982 to 1985 and is analyzing their data for publication in the near future (Elder, in prep). The Florida State Hospital at Chattahoochee discharges to Mosquito Creek, then to the Apalachicola. High phosphate concentrationsfrom detergents (Doherty
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4. Hydrology and Water Quality 1980) and high fecal coliform counts (Nil 1979) have historically been continuing problems in the creek. The Hospital failed static acute toxicity bioassays performed by the FDER in 1982 and 1983 (FDER 1982,1983). A 1984 FDER study of Mosquito Creek showed low total phosphorus levels but fecal and total coliform concentrations much above standards (McKnight 1984). Additionally, 5-day BOD could not be determined due to some bacterial inhibitor in the effluent. Sutton Creek, an Apalachicola River tributary, has experienced DO violations caused by the Blountstown sewage treatment plant (Kobylinski 1981). While this problem is expected to improve with scheduled plant upgrades, there remains the need to eliminate hydraulic overloads during wet weather. Apalachicola Bay has experienced problems with high coliform bacteria levels, which sometimes cause the bay to be closed to fishing. Much of this results from septic tank seepage in coastal communities and from poorly treatment discharges from area sewage treatment facilities. The City of Apalachicola Wastewater Treatment Plant has a long history of poor performance and environmental problems. New facilities are under construction and are expected to solve problems of poor discharge quality. During 198243, DO concentrations were above 4.0 pprn at all sites sampled by the Florida Game and Freshwater Fish Commission, but a summer (July-August) depression was noted between navigation mile 75 and 100 (Ager et al. 1983). Cox and Auth (1971) had similar findings; no explanation was offered in either instance. All water quality parameters examined during the Game and Freshwater Fish study met State standards. The only major point-source discharge to the Apalachicola River is the Gulf Power Scholz Electric Power Plant near Blountstown. This coal-burning pla~~tusesor~ce-thro~ghcoolingwater Irornthe rlver. The FDER and EPA have perm~tted outfalls which include nonwntact cooling water, ash pond water, low volume wastes, boiler blowdown, metal cleaning wastes, construction runoff, coal pile runoff, and sanitary waste. NPDES pH violations were noted in 1982 and illegal sanitary waste discharges were found in 1983 (FDER 1984a). A limited study of the plant's thermal discharge was performed in 1977 (Wieckowicz 1977) and also as a research project by the University of Florida. Winger et al. (1984) investigated river biota for residues of organochlorine insecticides. PCB's, and heavy metals. Elder and Mattraw (1984) looked at the accumulation of trace elements, pesticides, and polychlorinated biphenyls in river sediments and in the clam Corbicula maniclensis. This basin was sampled at four sites for biological indicatorsof water quality during 1975-78 (Ross and Jones 1979). The upper station was near the Bristol boat landing and, though only sampled a few times, it showed good macroinvertebrate diversity. This was also true of a station downstream, 2.5 km below the Chipola River cutoff (a connection above the confluence of the Chipola and Apalachicola Rivers where water from the Apalachicola flows into the Chipola: the Chipola below the cutoff consists primarily of Apalachicola water). The next station was in the Brothers River about 1.5 km above its confluence with the Apalachicola River. This area was basically undeveloped swamp, which was reflected in the good macroinvertebrate diversity. The nextstation, at Buoy No. 40inthelowerApalachicola River, showed a marginal Biotic Index and generally high diversity. Occasional high coliform bacteria counts were attributed to runoff. The final station was at the mouth of Lake Wimico (the head of the Jackson River). Here the macroinvenebrate diversity was generally high and the introduction of estuarine forms into the lake from the lntracoastal Watetway to the west was noted. The watershed south of Lake Seminole (i.e., the portion of the basin in Florida) is relatively pristine, and water quality in the river recovers during its transit. However, heavy-metal bearing sediments are being deposited in Apalachicola Bay from the Apalachicola and Chipola Rivers (FDER 1986~). Fishery studies suggest that, despite the alterations, the Apalachicola River is relatively productive (Bass 1983). Leitman et al. (1983) examined shallow groundwater movement in parts of the basin. They found that ground-water flow at Sweetwater, approximately 7 km north of Blountstown, was generally toward the river at low river stages and away from the river at high stages, but that ground-water flow from the uplands east of the floodplain showed constant flow
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Panhandle Ecological Characterization to the floodplain. At Brickyard, near Sumatra, ground-waterflowwas awaytromthe river at low and medium riverstages, but theground-water level was essentially equal to that of the river at high river stages. They felthat ground-waterflow at Brickyard was possibly toward the river at extremely low stages, but could not document this since these conditions did not occur during the study. Apalachicola Bay is a highly productive estuary, providing most of Florida's oysters and a nursery area supporting a substantial shrimp, crab, and finfish fishery. The bay is nevertheless suffering from developmental pressures and from the lack of cohesive plans to handle area wastes. These problemsare being addressed by State and local governments through establishing the river and bay as an Area of Critical State Concern. This designation allowsthe localgovernmentsto enlist the aid of State planning experts in developing methods to deal with area problems and requires them to follow a State management plan. The Area of Critical State Concern designation remains in effect until the State is satisfied that the local government has established programscapable of dealing with the problems. The Apalachicola River is believed to be the dominant factor controlling the seasonal Changes of nutrient levels and salinity, which drive the estuary and keep the tisherles potential of the estuary extremely high (Florida Rivers Study Committee 1985). The U.S. Army Colps of Engineers studied the Apalachicola River basin's water resources and discussed ground-water supplies (USACE 1981). Apalachicola Bay is not further discussed here since I has been thoroughly covered in a recent profile by Livingston (1984). In addition, further information may be found through Banks et al. (1983), a thorough (asof thedateof its publication) bibliography of llerature concerning the Apalachicola River basin. 4.7.4 Chlpola Rlver Basin (Flgure 53) The Chipola River, a major tributary of the Apalachicola, drains a 3,200 km2 area into the lower Apalachicola River. Eighty-two percent of this basin (2,640 km2) lies in Florida, with the remaining 18% (560 km2) lying in Alabama. The Chipola emerges from subterranean streams in southeast Alabama, flows generally south, then goes underground for a short distance north of Marianna, Florida. It reappears and flows south another 65 km to its confluencewiththe Apalachicola River nearwewahitchka. The Dead Lake area is formed where the natural levees of the Apalachicola River impoundthe Chipola above their confluence and produce a usuallyflooded area. A low dam was constructed to enlarge the lake, stabilizethe lake level, and enhance fishing access. Dead Lake, along with Lake McKenzie, MirrorLake, Turkey Pen Pond, and Merrits Mill Pond farther north in this basin, is among the 50 lakes in the State listed in Myers and Edmiston (1983) as most in need of preservation and protection. At the Chipola Cutoff above the confluence, approximately 25% of the Apalachicola River flow diverts to the Chipola River (Ager et al. 1983), where it constitutes the bulk of the Chipola River water below that point (Leitman et al. 1983). The largest spring in the basin is Blue Spring, located about 10 km northeast of Marianna. Blue Springs Creek flows from the spring into the Chipola River. The Chipola generally has good water quality (Hand and Jackman 1984) but was, in recent years, receiving indirect discharges via Dry Creek from a battery reclamation plant, Sapp Battery Company. Extensive damage has occurred to the wetlands near the Sapp plant site because of runoff contaminated with battery acid (sulfuric acid) and heavy metals. In 1970 Sapp employedfive people to crack used automotive batteries and recover lead. Bv 1978, 85 people were employed, cracking 50,000 batteries per week (Wans 1984). Acid from the batteries was dumped outside the plant building where it drained into a cypress swamp on company property. Water from this swamp drained south into a shallow lake named Steele City Bay, then through a series of cypress swamps into Little Dry Creek about a mile from the factory. Little Dry Creek is a tributary of the Chipola River via Dry Creek. By 1977 the acid had started to kill thecypress trees in Steele City Bay and beyond and, upon receiving complaints, the FDER became involved. After taking some unsuccessful steps to alleviate the off-site discharge and coming under legal action by FDER, Sapp abruptly closed down in 1980 (Wans 1984). In 1982 FDER began investigating the contamination under the U.S. EPA Superfund program. Contamination included lead, manganese, aluminum, and sulfuric acid. Approximately 17,500 m3 of battery
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4. Hydrology a1 id Water Quallty casings were buried on site to a depth of over 1 5 m with another 2,600 m3 piled on the surface. High levels of lead were found in most of the upper soils, the concentration generally decreasing with depth. At certain sites, which proved to be sinkholes, concentrations increased with depth to approximately 30 m. Sampling wells drilled in the bottom of one sink proved to be the most contaminated of any taken on the site, with extremely high levels of lead, manganese, aluminum, and sulfate, and somewhat lower levels of cadmium and nickel. It was concluded that water from these sinks was seeping into the Floridan Aquifer, and that concentrations of lead, cadmium and aluminum in samples taken from this aquifer under the Sapp site represented maximum theoretical solubililiesfor the metals (watts 1984). It was further concluded that the shallow aquifer was most likely to suffer widespread contamination; subsequent testing identified moderate to high levels of lead and aluminum contamination of this aquifer in a zone east of the site. Surface waters were also sampled for contamination. The on-site pondandcvpressswamp proved to be heavily contaminated with lead, mang'anese, and aluminum, with concentrations decreasing irregularly downstream until levels were indistinguishable from background concentrations at the most distant stations on Liltle Dry Creek. Concentrations measured in this study during 1983 proved to be significantly lessthan those obtained in an U.S. EPA study three years earlier (Wans 1984). This conchicola River in a 1978 study (Winger et al. 1984). The levels of lead in clams were, however, greater than those found in Apalachicola River clams. They speculate that Dead Lake may be serving as a sink for contaminants flowing down the Chipola, as the metal concentrations in sediments from the lower part of the lake were higher than those downstream of the Dead Lake dam nearthe Chipola's confluence with the Apalachicola River. Additionally, the only organochlorine pesticides found in the sediment samples were from those taken at Dead Lake. Simuttaneouslywiththe FDER study ofthe Sapp site, Little Dry Creek and Dry Creek were investigated as pa rtof an EPAsponsored study attempting to define similarities and differences between laboratory and field toxicity data(Livingst0n 1986a). The ecological effects of the gradient of contamination found downstream from the Sapp site provided a comparison to effects pfojected from similar toxicity gradients used in normal laboratory bioassay testing. At the same time the information concerning the effects of the Sapp contamination on the ecosystems of the creeks was documented. lamination isnow being cleaned up using State and Federal funds. The U.S. Fish and Wildlife Service (USFWS) examinedthefish,clams, andsediment inthe Chipola River in 1982 for possible effects trom the Sapp sfie contamination (Winger et al. in press). They found that while the levels of trace elements in samples of biota and sediments demonstrated no serious contamination in the Chipola River, metal concentrations generally increased downstream fromthe two stations located above the rivers confluence with Dry Creek. This increase was particularly noticeable for arsenic, cadmium, chromium, lead, and zinc in clam and sediment samples, though the arsenicand cadmium levels in the downstream biota were similarto those found in the biota of the ApalaThe Florida Departnlent of Health and Rehabilitative Services (HRS) in 1983 reported levels of lead in the introduced clam Corbicula above FDA levels for removal of food from the market place (Ageret al. 1983). Investigation of mercury contaminat~on In the Chipola is addressed by the FDER (1984b). Astudy in 1982 showed that the Chipola below the Dead Lakes Dam had moderately hard, very clear, and slightly acid water, but that the DO indicated an unusually high BOD upstream (Ager el al. 1983). The constant water level provided by the dam is killing trees and is allowing the growth of excessive aquatic plants. The dam is presently scheduled for removal (Banks 1983, Cason el al. 1984). There has been concern expressed about the potential for the release of substantial concentrations of heavy metals from the sediments trapped behind the Dead Lakes Dam when the structure is removed as planned (Bob Patton, FDER. Tallahassee; pers. comm.). This potential release would be the result of the anaerobic reaction of sulfur and iron. Four stations within the Chipola Basin were sampled for biological indications of water quality
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Panhandle Ecological Cheracierlzatlon during 1973-78 (Ross and Jones 1979). The uppermost station was downstream from Waddell's Mill Creek in Jackson County. Macroinvertebrate diversities were fairly high, but lower than expected; numbers of species collected were somewhat low, and the Biotic lndex was marginal. These results were attributed to heavy silt loads and subsequent degraded water quality from farming along the stream banks. The next station in the Chipola River at SR 274, east of Chason and upstream of Tenmile Creek, had high macroinvertebrate diversities and Biotic lndex values and showed a significant improvement during the study period. Occasionally, Class Ill (i.e., suitable for recreation, propagation and maintenance of a healthy, well-balanced population of fish and wildlife) bacteria standards were exceeded. This was possibly caused by the Marianna sewage treatment plant, though il was fen that it might be too far upstream to be the source of the fecal coliform bacteria. A third station was in Juniper Creek near Frink. This station showed high macroinvertebrate diversity and high Biotic lndex values Econtina Creek flows into Deer Point Lake, formed by the construction in 1961 of a dam across North Bay (USACE 1980a). Thisdam maintains the lake level approximately 1.5 m above sea level and provides the primary water source for Panama City. The water in the streams and lakes within the basin is low in dissolved solids because they are generally fed from surface runoff or from the shallow sand aquifer. This aquifer has little buffering effect, and as a result the surface waters have about the same mineral concentration as rainwater; this concentrationchanges little between periodsof high and low flow (Musgrove et al. 1964). Color and pH change with stream and lake stage as the proportion of water having contacted decayed organic materials increases. The pH normally ranges from 6.0 to 7.0 but falls below 6.0 during high flow. The exception to these generalities occurs in an area along Econfina Creekdownstream of a point east of Porter Lake, where springsfromthe Floridan Aquiferflowto the Econfina and increase dissolved solids concen-during the three times itwas iampled. High bacteria trations in proportion to the concentration of spring counts were attributed to runoff. The last stationwas water 1Musorove et al. 1964). just downstreamof the damwhich forms Dead Lake, ~ It was sampled only twice but had high macroinverteThe St. Andrew Bay system was studied in 1974 brate diversities both times. inorderto calculate a waste load allocation (i.e., the 4.7.5 St. Andrew Bay and Coastal Area (Figure 54) The St. Andrew Bay drainage basin encompasses approximately 3,500 krV and includes St. Andrew, West, North, and East Bays, St. Andrew Sound, and, to the east, St. Joseph Bay. There are no large rivers within the watershed; the largest inflow to the St. Andrew Bay system comes from EconfinaCreek, which mostof the year iscomposed predominantly of ground water from springs fed by the Floridan Aquifer (Musgroveet al. 1964). Muchot the terrain is very porous sands, which allow quick inf~itrat~on of rainfall. Stream baseflow within much of the area is maintained from the shallow sandy aquifer. The Deadening Lakes area (not to be confused with Dead Lake at the confluence of the Chipola and Apalachicola Rivers) at the northern end of the basin contains numerous sinkhole lakes formed bythecollapseof solution holes inunderlying limestone. Most of the lakes in this area have no surface outlets (Musgrove et al. 1964) and have subterranean connections. amount and quality of waste that can be discharged to the system based upon its calculated ability to assimilate that waste without damage to its ewsystem) (Johnson et al. 1974). During this study St. Andrew Bay had the poorest water quality ofthe four bays in this drainage. Some locations, particularly Watson Bayou and the International Paper Company outfail, dld not meet DO, turbidity, or bacterial standardsforClass Ill waters (i.e.. recreation, propagation and maintenance of a healthy, well-balanced population of fish and wildlife) The other bays generally met Class II standards (i.e., shellfish propagation or harvesting). The model produced in this study showed Watson Bayou to be quite sensitive to storm-water runoff, resulting in significant DO reductions. Ten years later, Hand and Jackman (1984) reported that of 400 krn2 of estuary in this basin, all but 14 km2 has good water quality. The major urban development in the area centers around Panama City. Major point sources of pollution include two large paper-pulp processing plants: the International
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Panhandle Ecological Characterization Paper Company, discharging to St Andrew Bay after treatment at the Bay County Regional sewage treatment plant, and the St. Joe Paper Company. discharging directly to St. Joseph Bay. Historically, problem areas include Watson Bayou, Martin Bayou, the area which used to receive the International Paper Co. discharge, and Deer Point Lake at the head of North Bay. Hand and Jackman (1984) report no data since 1981. Watson Bayou had DO, bacteria, and nutrient problems The bayou received discharge from the Millville Sewage Treatment Plant, which has since been dlverted to the regional treatment plant. Martin Bayou had pH, nutrient, and aesthetic problems caused, in part, by a limited assimilative capacity, discharge from two Small sewage package plants, and urban runoff. The area aroundthe International PaperCo.discharge into St. Andrew Bay had low DO, h~gh bacteria, and aesthetic problems: these discharges are now diverted to the regional plant. Deer Point Lake had low DObut is now, along with Crystal Lake and Gap Pond in Washington County, among the 50 lakes in the State listed in Myers and Edmiston (1983) as most in need of preservation and protection. Biological sampling of water quality during 1973-78 was performed at six stations within this basin (Ross and Jones 1979). A station in fast flowing Econfina Creek near the town of Econfina showed the stream supporting an excellent macroinvertebrate community with high diversity and very high Biotic Index values. Occasional high bacteria counts were anributedto runoff. Stations in East Bay eastof the mouthof Burnt Mill Creekand in West Bay on the gulf side south of Calloway exhibited good diversity and no trends were evident. Bacteria counts in West Bay exceeded Class II (i.e., shellfish propagation or harvesting) water quality standards. This was attributed to the greater development surrounding West Bay than is found around East Bay. A station in St. Andrew Bay near the entrance to West Bay and two stations in St. Joseph Bay, one off the T H Stone State Park on Cape San Blas and one off Port St. Joe, all had very high macroinverlebrate d~versitles and only occasional high bacteria counts. None of these three stations appeared10 have been degraded by pollution during this study period. Ground water in this basin, particularly near Panama City, lies in an area of the Floridan Aquifer of relatively low transmissibility. By 1963 groundwater levels had been lowered 61 m by pumping since the first deep well was drilled in 1908 (Musgrove et al. 1964). In 1964 pumping from one well field of 21 wells was stopped and water levels rose 50 m within 51 days. The aquifer east of East Bay was tested in order to estimate pumping drawdown and determine consequences of increased use as a source of irrigation water (Barr and Pratt 1981). This investigation dealt with the multilayered nature of the aquifer inorderto provide a more realistic estimate than that given by the simpler conventional methods. They found that the aquifercould beconsidered to be a low permeability layer about 90 m thick and a high permeability layer about 40 m thick. They concluded that heavy pumping from an irrigation well would be felt for several miles and that multiple wells would lead to substantial general water table decline. The NWFWMD also performed a reconnaissance of ground-water resources in southwestern Bay County (Barr and Wagner 1981). Area water resources and their potential for fulfilling future demands, flooding problems, and area navigation problems are addressed in a U.S. Army Corps of Engineers study (USACE 1980a). 4.7.6 Choctawhatchee River Basin (Figure 54) The Choctawhatchee River drains 12,030 krn2, of which 31% (3,700 km2) lies in Florida and 69% (8,330 km2) lies in Alabama. It is one of the four largest rivers in terms of flow in Florida and is second only to the Apalachicola River in floodplain area. In Floridathe riverisvigorous, slightly meandering, and heavily loaded with sediment. The Floridan Aquifer provides a major source of inflow to the river system (Hand and Jackman 1984). It travels 143 km from the Alabama border through an extremely swampy floodplain to Choctawhatchee Bay. At the mouththe flood plain is over 5 km wide and the river flows into the bay over shoals. The major Florida tributary is Holmes Creek, which flows approximately 80 km trom southeastern Alabama to its Choctawhatchee confluence near the town of Ebro. The river has been designated an Outstanding Florida Water (OFW), in part because its forested floodplain is virtually undeveloped and its basin is the least developed major river corridor in Florida Numerous
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4. Hydrology and I water Quality streams, springs, and lakes characterize this basin. Two lakes, Lake Victor in Holmes County and Smith Lake in Washington County, are listed by Myers and Edmiston (1983) as among the 50 lakes in the State most in need of preselvation and protection. The Choctawhatchee River is presently undergoing a State-funded baseline study underthe direction of Dr. Robert Livingston of Florida State Univers*y. The Federalgovemment authorized a navigable channel from the mouth of the Choctawhatchee River to Geneva, Alabama, just north of the FloridaAlabama border. However, commercial navigation was abandoned by the mid-1930's and Corps of Engineers maintenance ceased in 1942 (Florida Rivers Study Committee 1985). The strategic plan for regulating development within the basin was developed by the Florida Rivers Study Committee (1985). Six citieswith populationsgreaterthan5,OOO are located in this basin, five in Alabama and one (Chipley) in Florida. The largest Floridacities are Chipley, Bonifay, and Defuniak Springs. Some development in the river flood plain is beginning near Freeport and Caryville, primarily in the form of second homes. Caryville is the major community along the Choctawhatchee River in Florida experiencing flooding problems. The town was almost totally inundated in 1975 alter 45 cm of rain fell in 21 hours in the upper Pea River basin 1 month after a storm dropped 23 cm in 24 hours (U.S. Dept. of Agriculture 1975). This stormcaused severe erosiondamage to cropland as well. The severity of flooding was blamed on sediment deposition (Florida Rivers Study Committee 1985). To date the Corps of Engineers has concluded that the costs of flood control measuresforthe riverwould far outweigh the reduction in Rooddamage and the increased navigability. The NWFWMD also performed a study of sedimentation in the river (Musgrove 1983) and a flood reconnaissance (NWFWMD 1978a). Forestry and agriculture constitute the major land use in this largely undeveloped basin. Large timber companies own most of the land along the river. The Choctawhatchee is a moderately fertile. alluvial river and is the richest in nitrogen and phosphorus of the Panhandle rivers, a result of the high clay content of basin soils and the runoff-promoting relief, as well as from anthropogenic nutrient inputs. The majority of sedimentation originates in the agricultural land of Alabama along the Choctawhatchee and Pea Rivers (Florida Rivers Study Committee 1985). The water quality of the river in Florida is generally good except for its high sediment load. The river is probably the only economical source of potable water for the massive coastal development predicted for southern Walton County (Florida Rivers Study Committee 1985). Twenty-four sewage treatment plants discharge into the Alabama portion of the drainage basin, eight into the major tributary Pea River and sixteen into the Choctawhatchee and its smaller tributaries. In addition, nine industrial sites discharge into the Alabama portion, four into the Pea River and five into the Choctawhatchee and its tributaries. Nonpoint sources throughout the basin, particularly in Alabama, include extensive agriculture, including dairy and hog farms. Florida discharges causing water quality problems include sewage treatment plants in Chipley discharging to Alligator Creek, in Graceville discharging to Holmes Creekvia Little Creek, and in Bonifay discharging to Holmes Creekvia Camp Branch. These plants have caused bacteria, DO, and nutrient problems in the Florida portion of the basin (Hand and Jackman 1982, 1984); however, Graceville and Bonifay are upgrading their plants which should improve the water quality in this area. Additional water quality problems are caused by the Defuniak Spring sewage treatment plant discharging to Sandy Creek and a chicken processing plant discharging to Bruce Creek via Carpenter Creek (Hand and Jackman 1984). Improper logging methods in Washington County, primarily clearcutting near surface streams and rivers, are increasing the sediment problems in the river. Because timber isthe dominant industry in the area, any regulation to curb the practice is expected to be slow to occur (Florida Rivers Study Committee 1985). Holmes County is aware of sedimentation originating in the county and is working with the Soil Conservation Service to construct watershed projects to reduce it.
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Panhandle Ecological Characterlzatlon Biological sampling was performed at stations within the basin during 1973-78 for indications of waterquality (Rossand Jones 1979). Stations in the Choctawhatchee River at SR 2 near the Alabama border and at SR 20 near Ebro had high Biotic Indices from qualitative macroinvertebrate sampling. Quantitative macroinvertebrate sampling showed high diversity at the SR 20 station. Both stations characterized the river as clean and fast flowing. Both stations also had rather high bacteria counts, especially the one at SR 2. Stations in Holmes Creek, at SR 2 near Graceville and at SR 79 nearvernon, both had moderately high macro-invertebrate diversities and occasional problems with bacteria. Showell Farms, an industrial point source, has been identified by the FDER district office as a significant polluter of Bruce Creek, a Choctawhatchee tributary. Fish communities in the Florida portion of the basin are considered healthy (Bass 1 983). Leaking gasoline from a small service station in northwestern Holmes County has contaminated the Floridan and Claiborne aquifers underlying the site (Busen et al. 1984). Corrective actions have been taken by FDER. Flooding problems, area navigation problems, and area water resources and their potential for fuifilling future demands are addressed in a U.S. Army Corps of Engineers study (USACE 1980a). 4.7.7 Choctawhatchee Bay and Coastal Area (Figure 55) This 1,190 kmzcoastal basin is drained by Lafayette, Magnolia, Alaqua, Rocky, Turkey, and Juniper Creeks. The largest stream is Alaqua Creek which drains 324 krnz. These streams have a high base flow (i.e., minimum flow) which is attributed to seepage fmm the Sand and Gravel Aquifer (USACE 1980a). In 1978-79 baseflowconstituted 92%-98% of the total runoff from Turtle, Juniper, and Turkey Creeks in southern Okaloosa County (Barr et al. 1985). Choctawhatchee Bay, 40 km long by 5 km wide, averages 3 m in depth at the eastern end where the highly alluvial Choctawhatchee River flows into the bay (Musgrove 1983), and 9 m in the remainder of the bay. It receives flow from a watershed which includes the Choctawhatchee River and which totals approximately 13,830 km2. The bay is characterized by its minimal connection with the Gulf of Mexico. East Pass, a narrow channel west of Destin and east of Santa Rosa Island, is the only connector and is often shoaled to a depth of 2 m (Collard 1976) requiring maintenance dredging to keep a 4 m channel open (USACE 1975). Fort Walton Beach, Destin, and Valparaiso are the largest cities in the basin, and the area around these cities along the gulf coast is undergoing rapid urban development. A State-funded, in depth ecological baseline study of Choctawhatchee Bay during 198546 was recently completed (Livingston 1986b). Forty eight stations were monitored to provide information for preserving the bay in the face of expected massive development of surrounding lands. This study was prompted by plans to construct a bridge over the middle of the bay between White Point and Piney Point. Similar bridges were constructed in other bays without proper understanding of the factors controlling the estuary ecosystem, causing marked damage to the fisheries in parts of those estuaries (e.g., the St. George Island bridge in Apalachicola Bay). This study concluded that the proposed bridge can be constructed with minimal environmental damage if (1) observed seagrass beds in the vicinity of White Point and Piney Point wereprotectedduring the varous stages of bridge construction and operation, (2) storm-water~nofffromthe completed StNcture was processed adequately to prevent water quality deterioration in the bay, and (3) causeway construction was kept to a minimum to avoid direct habitat destruction and possible changes in the flushing rates of the areas at depth in western sections of the bay. According to long-term area residents, during heavy flooding in the late 1920's, East Pass formed due to a "blow-out" of bay water (Livingston 1986b) Resulting higher salinity levels within the bay were associated with losses of the well-developed ernergent and submergent vegetation, and a reduced fishery. Vertical salinity stratification was found in the deeper portions of the bay. These areas (especially inthecentralandwestem bay) also hadvertical stratificationof DOand were hypoxic at depth during various times of the year.
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Panhandle Ecological Characterization The low range of tides (averaging 0.2 m within the bay and 0.4 m in the adjacent gulf) produces minimal tidal flushing. This, combined with the fact that the salt water input is at the opposite end of the major source of freshwater input, results in poor mixing of bay waters. Bay salinity gradientsfoliowed river flow fluctuations; lowest salinities were found from Decemberthrough April at the bay surface and highest salinitieswerefoundduringsummer-fall. As a result of these factors, the deeper water of Choctawhatchee Bay is some of the most stratified in the Panhandle, with the western two-thirds being sharply stratified and the eastern third weakly stratified (Collard 1976, Livingston 1986b). These conditions tend to produce a situation where the underlying high sallnity water stagnates. Collard (1976) found that in summer the bottom of the bay was "biologically barren." Livingston (1986b) found that low DO levels associated with the salinity gradients in the deeper portions of the bay were life-limiting to various estuarineformsduring certain mnthsof the year. Low DO was most evident during summer months and by August the entire bay was hypoxic to anoxic at depth. The baseline study also found that nitrogen leveiswere highest inthewesternsectionsofthe bay (Cinco. Garnier, lower Rocky, and Boggy Bayous). Phosporus levels were also highest in the western end (Old Pass Lagoon, lower Rocky and Boggy Bayous). This was attributed to storm-water runoff from the Destin peninsula and adjacent developed areas. Pesticide and heavy-metal analyseswere not performed in the study, but it is suggested that improved management of the Choctawhatchee River basin (e.g.. regulation of pesticideuse, municipal waster disposal, etc.) might improve the relatively low productivity found in the easternpoflionsof the bay. A tabulation of past data and an excellent bibliography on the Choctawhatchee Bay system was compiled by the Northwest Florida Water Management District as it began development of an area management program (Northwest Florida Water Management District 1980b). This report cites a 1978 study ofthe bay (TaylorBiological Co. 1978) as being oneof the mostusefulasaguideforpolicy and decision making. The NWFWMD has compiled all their studies of the bay into one report (NWFWMD 1986). Included inthecompilation is an investigation of the extremely high temperatures found below the halocline during 1984 sampling (Maristany and Cason 1984). The cause of this has not been resolved. Awaste-load allocation study was pedormed on the bay using awaterquality modelfromthe University of South Florida(Johnsonet al. 1974). Thismodel examined the salinity, DO, N, and P concentrations, and the 5-day BOD. Water quality was found to be generally good with the exceptions of the Cinco, LaGrange, Boggy, and Alaqua Bayous, and nutrient levels in most of the bay indicated no eutrophication processes in existence. Their model indicated that conditions in Cinco and LaGrange Bayous could be improved by requiring secondary treatment for all discharges to the bay. They also expressed concern for the effects of urban runoff from future land development along the shores. Stations in the basin were sampledfor biological indications of water quality during 1973-78 (Ross and Jones 1979). A station a few kilometers up Lafayette Creek showed consistently high Biotic Index values from qualitative macroinvertebrate samples. Nutrient-enriched runoff from a large nearby farm contributed to the lush growth of aquatic plants. At a station in Choctawhatchee Bay near Fort Walton Beach macroinvertebrate diversities suggested a fairly healthy community. A station in the bay near Piney Point showed a significant decline in macroinvertebrate diversity during the sampling period. Both the bay stations were being influenced by the rapid development in the west end of the bay. Occasional occurrences of bacteria levels inexcessof Class II (i.e., shellfish propagation or harvesting) water quality standards were noted at the Piney Point station, though counts were generally low. According to Hand and Jackman (1984) the Choctawhatchee Bay basin has historically had good water quality in all areas and at present Old Pass Lagoon, which drains the coastal areaof Destin, istheonlyareaexhibitingpoorwaterquality. This small lagoon is in the process of becoming a landlocked salt lake due to the natural shifting of coastal sand, and achannel is maintained by dredging. The
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4. Hydrology an lagoon has poor circulation and receives nutrients from surrounding housing developments and possibly from the drainage of nutrient-enriched shallow ground water from a nearby sewage treatment plant spray field (Donald Esry, Northwest Florida Water Management District; pers. comm.). The circulation problems are aggravated by the presenceof numerous dredge-and-fill constructed finger canals. As a result Old Pass Lagoon suffers from low DO levels and frequent fish kills. The Northwest Florida Water Management District is planning to install a large pump to transfer water from the Gull of Mexico into the lagoon to enhance the circulation and ease the water quality problems. d Water Quality largest towns in the basin. The main sources of pollution in the area include agricultural and urban runoff and domestic sewage discharge (Hand and Jackman 1984). The only problem area in the basin is Trammel Creek, which receives treated sewage from the Crestview sewage treatrnent plant. This discharge caused nutrient and bacterial problems in the creek, but assimilation is complete and water quality good bythetimethecreekreachestheYellow River. Crestview is in the process of upgrading their plant. A 1979 train derailment spilled anhydrous ammonia into the Yellow River just below its confluence with Trammel Creek. Hand and Jackman (1984) reported that the river benthos in the area of the spill still showed reduced diversity. con~~,"n~~~~~ ~"h",~!~~a~~~e~ro~~ y:E: The Yellow River exhibits only lairto good water 1983). Additionally, they investigated !he ground quality in Alabama because of DO, nutrient, and water near the wastewater percolation ponds in bacterial violations associated with sewage treatDestin for increased nutrients (Barr and B~~~~~ ment Plant discharges. The Yellow River has not rnors been extensivelv samoled. thouah indications are nau4,. .. that the river in iorida is reiativel;uns~oiled 1FDER Area water resources and their potential for fuC filling future demands, flooding problems, and area navigation problems are addressed in a USACE study (USACE 1980a). The USACE also prepared a report concerning coastal storm flooding in the Destin area (USACE 1970). The highest flood tide reported occurred in 1926 and was 3-3.5 m above mean sea level on the beach. The most severe storm tide expected, given area conditions, was predicted to be 4.25 m above sea level. These calculations did not take into consideration the predicted, relatively rapid rise in world-wide sea level (Hoffman et al. 1983) (see section 4.8.1). 4.7.8 Yellow River Basin (Figure 55) The Yellow River drains 3,540 km2, of which 63% (2,220 km2) is in Florida and 37% (1.320 km2) is in Alabama, and drains into Blackwater Bay. This river, along with its only major tributary, the Shoal River, and the neighboring Blackwater River are considered classic sand-bottom streams (Beck 1965). The waters are clear and of relatively low primary productivity. In this basin, Lake Jackson, Juniper Lake, and Oyster Lake are listed by Myers and Edmiston (1983) as among the 50 lakes in the State most needing preservation and protection. Forestry is the predominant land use with agriculture second. Milligan and Crestview are the 1986~). Sampling at a station in the ~lioal and in the Yellow Rivers during 1973-78 showed healthy macroinvertebrate communities and no signs of DO deficiencies (Ross and Jones 1979). Occasionally high total coliform bacteria counts from the Shoal River station east of Crestview were attributed to agriculturalrunoff. Higherfecalcoliformcountsfrom the Yellow River station southof Holtwere attributed to the Crestview sewage treatrnent plant. 4.7.9 Blackwater River Basln (Flgure 56) The Blackwater River drains 2,230 km2 of which 81% (1,810 km2) is in Florida and 19% (420 km2) is in Alabama. The river originates north of Bradley, Alabama and flows south to Blackwater Bay. Groundwater seepage from the Sand and Gravel Aquifer provides much of the riverflow (USACE 1980b. Hand and Jackman 1984). Most of the watershed is wntalned within two State forests, the Conecuh in Alabama and the Blackwater in Florida. Thus forestry is the predominant land use, with agriculture of secondary importance. The river's major tributaries include Panther, Big Juniper, Big Coldwater, and PondCreeks. The Blackwater River, a clear, sand-bottomed stream, has been designated an OFW (i.e.. no significant degradation allowed) and receives heavy recreational use. Within the basln, Hurricane Lake. Lake Karick, and Bear Lake are listed by Myers and Edmiston (1983) as
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4. Hydrology and water Quality (Hand and Jackman 1982, 1984). Below this point, macroinvertebrates have been reduced to fewer than ten pollution-tolerant species. The Milton plant is being extensively upgraded, which is expected to improve the area water quality. Fish and macminvertebrate populations in the remainder of the river are considered exceptionally healthy (Bass 1983) despite agricultural runoff and several point-source effluent dischargers. Biological water-quality stations in the basin were sampled during 1973-78 (Ross and Jones 1979). A station in Big Coldwater Creek had a high Biotic lndex from qualitative sampling, indicating no significant organic pollution. A station in the upper Blackwater River near SR 4 exhibited high macminvertebrate diversities for two types of quantitative sampling and a high Biotic lndex for qualitative samples. Occasionally high total and fecal coliform counts were attributed to pasture and other agricultural runoff. These numbers sometimes exceeded Class Ill (i.e.,recreation, propagation and maintenance of a healthy well-balanced population of fish and wildlife) waterquality standards. A station at the mouth of the river in East Bay had a moderate species diversity and a low number of species per sample, which was attributed to the estuarine conditions. The occurrence of frequently high total coliform bacteria counts were attributed to the Milton sewage treatment plant upriver and to area ~noff. The USGS is mnitoring a waste injection well near Millonforpotentialground-watercontamination (Pascale and Martin 1977). 4.7.10 Escambia Rlver Basin (Figure 56) The Escambia Riverdrains 10,960 kdof which approximately 10% (1,080 kmz) is in Florida and 90% (9,880 km2) is in Alabama. The river is formed by the confluence of Escambia Creek and Conecuh River at the Florida border. The basin has a limestone base with poorly drained organic surface soils near the coast, such that the river flows through a generally low, swampy area with many sloughs and backwaters from Molino, Florida, to Escambia Bay (Hand and Jackman 1984). These conditions change to well-drained sandy soils in the northem portions of thedrainage. Despite these well-drained soils, topographic relief is sufficient to renderthis area susceptible to erosion (FDER 1986~). The basin is lightly populated withonly two cities, Cantonment and Century, having populations greaterthan 5,000. Most ofthe basin is forested and, together with some agriculture, this constitutes the major land use. There are approximately 260 km20f floodplain crop and pasture land. Flood peaks occur primarily in April and May, with high river stagesalso commonin December. It is recommendedthat crops be planted and construction take place at least 7 m above the mean river stage to minimize flood damage (USACE 1980b). Historic baseline water quality data for the Escambia River includes a study by Patrick (1953). Thirteen point-source dischargers have State or Federal permits to discharge into this basin. Five sewage treatment plants and five industrial sources (primarily paper and chemical companies) discharge into the basin in Alabama including the Container Corporation of America--Brewton Mill (US. EPA 1971a). In Florida, Monsanto Chemical discharges inorganic effluents into the Escambia River, and two small towns near the Alabama-Florida border, Jay and Century, discharge effluent fmm sewage treatment plants. The Escambia River has a history of water quality problems (U.S. Dept. of the Interior 1970b). U.S. EPAwaterquality indexvalues for DO, color, and bacteria downstream of Alabama point sources in the past have been fair to poor (Hand and Jackman 1984). Recent samplings show that bacterial standards for Florida Class Ill waters (i.e., recreation, propagation and maintenance of a healthy, well-balanced population of fish and wildlife) are not being met in the Escambia River near the Alabama border (Hand and Jackman 1984). Fish communities are recovering from past degradation; however, they remain less healthy than expected (Bass 1963). Fishery investigations bythe FloridaGame and Fresh Water Fish Commission suggested that the river was in an intermediate stage of recovery from the past pollution (Bass and Hitt 1978, Bass 1983). Effluent from the sewage treatment plant for the Florida town of Century causes bacterial violations downstream in the Escambia River. The recent reduction in monitoring activity has made it impossible to distinguish between river impacts originating in Alabama and in Florida. At the lower endofthe Escambia River at the
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Panhandle Ecological Characterlzatlon mouth of Governors Bayou three of five DO measurements taken during 1981-83 were below 3 mgl (Hand and Jackman 1984). Canoe Creek, a tributary of the Escarnbia River, has experienced some water quality problems from nonpoint source runoff (FDER 1978). The 1978 study noted increasing bacterial levels, decreasing pH, and relatively high nitrate concentrations from 1975 to 1978. Only one point source discharges10 the stream, Bluff Springs Campground sewage treatment plant. FDER concluded that this source was not responsible for the problems and tentatively attributed the low pH to substantial input of the unbufferedwater ofthe Sand and Gravel Aquifer and the bacteria and nitrate levels to pasture and woodland runoff. The creek demonstrated bacterial violations in 1983, attributed by the FDER district office to dairy and other agricultural stormwater runoff. In addition, siltation and turbidity remain problems in Canoe Creek, especially after rainfall. In the central part of this basin, nearthe town of Jay, the University of Florida operates an IFAS (Institute of Food and Agricultural Sciences) agricultural researchcenter. The FDER investigatedthe site in 1984 following complaints that the pesticides and herbicides tested at the center were being improperly disposed of (Busen et al. 1985). Three separate samplingtripsconfirmed pesticides at high levels as deep as 4.5-6 m in the soil at the pesticide mix-wash area, in the drainage ditch, and in the field to whichthe runoff was d~verted. Leftoverpesticides and wash water were dumped into the drainage ditch, which flowed to gravel-filled pits built to increase percolation. An on-site dump in which pesticide containers containing chemicals were found also showed soil contamination from pesticides. No ground-water contamination, however, was detected. The deepwater table and numerous clay layers in the soil limit the potential for pesticide migration into theground water. This incident raised concerns about the other 22 IFAS centers where similar disposal methods and the normal sandy soils of the State might pose a hazard to area ground water. Macroinvertebrate diversity was monitored at three stations in the Escambia River from 1973 to 1978 (Ross and Jones 1979). These data suggested that the river was recovering from the massive pollution present during the 1950's and 1960's (FDER 1986~). The station in the river near the Alabama border showed significant improvement during the study period. Diversity indices and the Biotic Index indicated afairly healthy, stable macroinvertebrate community. However, the combination of very high total coliform bacteria populations and low fecal wliform populations suggested a marked impact from a large paper mill upstream. A second station at Upper Bluffs, approximately 18 km upriver from the rivets mouth had high macroinvertebrate diversities, high Biotic index values, and also showed a significant trend of improvement. Occasionally high bacteria counts were attributed to runoff. Thesaltwedgefrom Escambia Bay reachesthis station during low flow conditions and estuarine forms are found here. The third river station was at the mouth at US 90. Itwastentatively concludedthat the estuarine conditions found there, combined with thermal effluents, oil and grease spills, and PCBcontaining sediments, may have lowered macroinvertebrate diversities. Occasional high coliform wunts were apparently caused by runoff. 4.7.11 Escarnbia Bay and Coastal Area (Flgure 56) The Escambia Bay coastal area (including Pensacola, Escarnbia, East, and Blackwater Bays and Santa RosaSound) drains approximately 1,410 km2. The bay system receivesflow from a watershed including the Yellow, Blackwater, and Escambia Riversand totalling some 18,130 km2, of which 6,525 km2 (36%) is located in Florida and 11,605 km2 (64%) inAlabama. Majorinflowstothebay systemarefrorn the Escambia River (185 m31s) and the Blackwater River (11 m3/s). The bay is relatively shallow, rangingfrom less than 1 rnto 6 mdeep and averaging 2.5 mat mean lowwater(U.S. EPA 1971a). Waterdepth increases from the northern end southward. Ellis (1969) described some of the basic dynamics of the estuary and labeled it a low energy estuary. Escambia Bay was studied during a period of low river flow in 1969 (U.S. Dept. of the Interior 1970a) with afollow upduring high riverflow in 1970 (U.S. EPA 1971 b). These studiesfound that Escarnbia Bay sediments are htghly organlc and that tidal circulation in upper Escambia Bay is poor. Therefore, disturbing the sediments (e.g., dredging) can cause severe oxygen deplet~on and massive fish
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4. Hydrology an d Water Quality kills. These studies reported unconsolidated bottom sediments ranging from approximately 0.5 m to greater than 2 m, with about one-third of the bay covered to a depth greater than 2 m. Circulation in the bay is generally clockwise during high and low river stages. Water flows out the west side of the bay and saline water flows into the east side. During low flow periodsthe smallcreeks intheextreme nolthern end of the bay do not discharge sufficient water to flush the area, and pollutants are effectively trapped. The studies further determined that the pilings (most of which were unused and unnecessary) of the railroad bridge across the middle of the bay restricted circulationbetween the upper and lowerbay. An investigation of bottom benthos (US. EPA 1971 b) suggested that wastesdischarged along the eastern shore from American Cyanamid and Escambia Chemical companies were generally swept norlhwestward and deposited along with wastes from Monsanto and Container Corporation in the central and western portions of the upper and lower bay. An enforcement conference in the late 1960's (U.S. Dept. of the Interior 1970b) led to bay recovery studies by U.S. EPAduring 1972-73 These studies resulted in more stringent controls on municipal and industrial discharges. In 1975, following a study of the area's capability to deal with the pollutant loads it was generating (Henningson, Durham 8 Richardson, Inc. 1975, Olinger et al. 1975), it was concluded by the West Florida Regional Planning Council that (1) there should be no additional nutrient loads discharged to Pensacola Bay, and (2) all domestic sewage discharges should be removed from. Perdido Bay, Big Lagoon, Escambia Bay, East Bay, Blackwater Bay, and Santa Rosa Sound. Hand and Jackman (1984) report that most of the bay system has good water quality; however, several of the bayou areas which receive treated sewage, industrial wastes, and urban runoff exhibit significant water quality problems. Bayou Chicn drains part of the Pensacolaurban area, receives treated industrial waste and treated sewage from Warrington Sewage Treatment Plant via Jones Creek and until recently from Pen Haven Sewage Treatment Plant via Jackson Creek, and has bacteria and nutrlent problems (Hand and Jackman 1984) The Pen Haven plant has been closed and its waste load diverted to the Main Street Plant As a result Jackson Creek is improving. Bayou Texar drains the center of Pensacola and, thoug:. there are no permitted point sources in its drainage, has shown bacteria and low DO problems. This bayou ison the westernsideof Escambia Bay and the only stream flowing into it is Carpenter Creek. The creek and bayou are over 13 km long but the bayou varies in width from about 30 m to a maximumof about 425 m. (NWFWMD i978b) The creek is intermittent in some sections and apparently receives little base flow, depending on runoff to maintain flow. Bayou Texar undergoes wide fluctuations in depth depending on local weather conditions, experiencing "flooding" caused by water pileup as well as exposure of large expanses of bonom when water is blown away. In 1974 a restoration study was prepared for the State (Henningson, Durham & Richardson 1974). This study concluded that the major cause of water quality degradation was sediment deposits on the bonom resulting from uncontrolled development in the basin. Further studiesensued todeterminethe nature and extentof siltation in the bayou and the effect of the siltation on local hydrology (NWFWMD 1978b). This study detailed changes in the bayou since 1893 and described erosion problems of surrounding lands and subsequent transport of the eroded sediments through the bayou. Hand and Jackman (1984) report no recent (since 1981) data on this area. Water quality problems exist in the northern part of Escambia Bay with reduced DO concentrations and bacteria problems around the mouth of the Escambia River. The University of West Florida Sewage Treatment Plant effluent and Monsanto industrial effluents are discharged to the river just upstream of the mouth. Mulano Bay, on the east slde of Escambia Bay, has had DO, nutrient and bacteria problems but Hand and Jackman (1984) report no data since 1981. Blackwater Bay exhibits water quality problems primarily attributable to nutrients at the Blackwater River mouth. These are attributed to the nutrient loads carried by the river. Pensacola Bay, particularly the area near Pensacola, was monitored as part of an investigation of the effects of discharges from the Main Street
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Panhandle Ecologlc Wastewater Treatment Plant (McAfee 1984). This study showed the bay to be highly stratified and poorly flushed. They reported improved conditions from studies taking place in the mid-1970's. The western half of Santa Rosa Sound was studied for its potential for reclassification asashelk fish harvesting water (Florida Department of Health and Rehabilitative Services 1970). The study concluded that, at that time, the western part of the Sound should be reclassified for shellfish harvest since it had excellent water quality, no sources of industrial pollutants, and a watershed little larger than the area of the Sound. Five sewage treatment plantsdid, however, discharge intothe Sound. It was recommended thatthese be forced tofind alternative discharge points outside this area. Santa Rosa Sound was studied again in 1977-79 (Moshiri et al. 1980). The researchers concluded that the Sound exhibited Serious degradation of water quality relative to other local estuarine systems;duringwarm months red tideoutbreaks were possible. Additionally, LiileSabineBay, Onthe western end of the gulf side of Santa Rosa Sound, exhibited signs of eutrophication evidenced by high nutrient concentrations, low water transparency, increased algal populations, and low DO. They recommended no further discharges be allowed to Little Sabine Bay. charged effluents into two unlined surface Impoundments which are in direct contact with the Sand and Gravel Aquifer, the principal source of water in the area. The USGS chose this site in particular for further study because it is typical of other industrial storage impoundments, the phenols involved are very toxic, and it gave ease of access lor sampling (Troutman et al. 1984). They have placed monitoring wells surrounding the site and are sampling the nearby areain Pensacola Bay (Troutmanet al. 1984, USGS 1984). Total phenol concentrations in water samples from a test well 30 m south of the impoundment were 36.000 pgll at a depth of 12 rn but less than 10 pal atadepth of 27 m (Troutman et al. 1984). Other test wells indicated that contaminated ground water may not bedischargingdirectly into Pensacola Bay. However, phenol concentrations in samples from a drainage ditch discharging directly in Bayou Chii exceeded 20 @I. Deep-well waste injection is used by several of the industries in the Pensacola area. The USGS has been doing substantial investigationsof this method, studying movementsof the injectedwastes (Pascale 1976, Pascale and Martin 1978. Hull and Martin 1982, Merritt in press) and chemical changes in the wastes following injection (Ehrlich et al. 1979, Hull and Martin 1982, Vecchioli et al. in press) to ensure that it will not contaminate areaground water. These programs are ongoing. duri~b~~~~~~~ ~~~$~,","d~~~,"e~~~~~i,","~ The USGS performed an early ground-water insities ranging from near zero (very poor) to 3,3 vestigation near Gulf Breeze in Santa Rosa County, (good) with no trend of improvement evident (Ross identifying two shallow aquifers separated by a clay and Jones 1979), The apparent instability was confining layer (Heath and Clark 1951). They have attributed to the estuarineenvironment and stresses maps showing flooding along the from variable industrial discharges into the bay. A coast during Hurricane Frederick in 1979 (Franklin similar station in Pensacola Bay was well flushed and 'Ohman 1980' Franklin and Scott 1980' with marine waters and population and species and Franklin 1980) and published a summary of diversity values suggested a fairly stable macroinground water and surface data for Pensacola vertebrate community. A final station in Santa Rosa and County lge2). Sound at Upper Pritchard Point generally exhibited moderate macroinvertebrate diversities with no significant trend and no notable bacteria problems. 4-8 "ydrology and Water This last station is probably more closely associated Quality with Choctawhatchee Bay than with the Escambia 4.8.1 Hydrologic Concerns Bay system. The frequency and magnitude of floods usually The American Creosote Works, Inc. has treated Increase as drainage basins are developed. Floodwood at a site in Pensacola for 70 years and dising is a necessary and desirable part of the river
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4. Hydrology and I Water Quality basin ecosystem's energy flow; however, their frequency and magnitude can easily exceed levels needed to maintain the ecosystem if improperdevelopment takes place. Enforcement of prudent construction practices designed to retain or slow runoff can minimize this increase and its effects on human development. Minimizing vegetation removal (especially trees), prohibiting ditch-and-drain operations aswell asdredge-and-fill construction (particularly in wetland areas), andpreventing, ortightly controlling, construction and development in river flood plains are all necessary to minimize excessive flooding. Summer rainfall may be reduced if future development increases the area's albedo (surface reflectivity). It has been proposed that convective rainfall has been reduced by albedo changes from extensive wetland draining in south and east Florida (Gannon 1982). The Panhandle has a lower percentage of wetlands than did these regions origlnally, yet summer rainfall patterns are similar, with afternoon seabreezes reacting with updrafts from the heated land mass to form thunderheads. The potential for human alterations of Panhandle albedo causing altered rain patterns seems likely; however, programs underway by State and Federal agencies appear to be minimizing those alterations. A hydrologic change celtain lo have substantial impact in at least the coastal areas of the Panhandle is the rising sea level. Projections in reports published by the U.S. EPA (Hoffman et al. 1983,1986) andthe National Academyof Sciences (Revell 1983) predict aglobal sea level rise ranging from as little as 38cmtoasmuchas211 cmoverthenext I00 years. The most recent estimates (Hoffman et al. 1986) predict a global rise of between 57 and 368 cm by 2100. This rise, coupled with coastal subsidence in the Panhandle from tectonic activity totalling approximately 13 cm would result in a net sea level increase along the Panhandle coast of from 70 to 381 cm (roughly 2.3 to 12.5 it). This compares to a net increase over the last century of approximately 1C-15 cm (Gornitz et al. 1982, Barnett 1983). The rate of rise increases with time; the 25-year estimates and cumulative totals through the year 21 00 are given in Table 5 and Figure 57. Impacts from sea level rise will be manifold but can be placed in three broad categories: shoreline retreat, temporary flooding, and salt intrusion. Besides inundating lowlying coastal areas, coastal erosionwill progress inland agreat distance. Statewide, average horizontal encroachment by the oceans in the next 100 years is expected to be approximately 100 times the vertical rise (i.e., 51-224 m) (Bruun 1962). The actual encroachment experienced will bestrongly dependent on the local terrain. This high ratioisaneffect explainedbytheBruun Rule. Briefly, this rule states that beach erosion occurs to provide sediments to the shore bonom so that the shore bottom can be elevated in proportion to the rise in sea level. Thus sufficient beach will erode to provide the same shore bottom-beach slope from some distance offshore that was stable prior to the sea level rise (Figure 58). The current trend of sea level rise may be responsible for serious erosion taking place in many coastal resorts (New Jersey Department of Environmental Protection 1981, Pilkey et al. 1981). Most of the Panhandle can probably expect a ratio lower than the Florida average since maintaining the relatively steep nearshore slope of the mostly high energy coastline will result in somewhat less lateral encroachment. However, the barrier islands along much of the Panhandle will be strongly affected, migrating landward where possible and experiencing heavy erosion on the seaward faces. Table 5. Scenarios of future sea-level rise (In cm) (Hoffman et al. 1986). Scenario 2000 2025 2050 2075 21 00 High 5.5 21 55 191 368 Low 3.5 10 20 36 57
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Panhandle Ecologlc al Characterlzatlon Figure 57. Projected sea-level rise uslng different scenarios (data from Hoffman et al. 1983). The increased depth of the water near shore in those areas where artificial or natural structures prevent sediment erosion from the beach, according to the Bwun Rule, will allow more energetic waves to strikethecoastline. Areassuffering temporaryflooding will increase behind these structures since storms, including hurricanes, will result in higher "storm surge" levels. Many present coastaldevelopments and cities will be much more vulnerable to storm damage. Impact scenarios have been developed for Galveston, Texas, and Charleston, South Carolina (Barth and Titus 1984). These models indicate that substantial damage will occur in these twocities, but thatthe extentcan be ameliorated and substantial losses prevented by taking anticipatory actions. Although buildings are frequently designed assuming a 30 year life, the patterns of development resulting from construction of roads and certain key commercial property (e.g., factories, utilities, airports) may determine patterns of development for centuries. Consideration of the changing sea level should be made a part of planning and permitting, particularly for these key structures. Barrier island development is probably foolish in nearly all instances. The rising sea level will, by increasing the hydraulic pressure of the saltwater, lncrease saltwater intrusion into the aquifers in coastal areas. The potentiometric pressures in the aquifers along the coast suggest that the saltwater intrusion will be felt along the entire Panhandle near-coastal area and will have the greatest effect in those areaswhere the aquifer potentiometric pressures have already been reduced to levels near or below sea level (Figure 52). Southern Okaloosa county is presently the most extreme case of ground water over-pumping in the Panhandle. Areas in the Panhandle rnosr affected by sealevel rise may be the barrier islands, coastal wetlands, and those coastal areas with present elevations less than a few meters above sea level The wetlands will tend to mlgrate inland except where development prevents it. 4.8.2 Water Quality Concerns a.Surfacewater. Thefurlher reductionof pointsource, surface-water pollutants from Panhandle Volume eroded from A must equal that of needed to brlng nearshore sea floor level up a d~stance equal to the rlse In sea level Flgure 58. Diagram showing Bruun Rule tor beach erosion following lncrease In sea level. 106
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4. Hydrology ar ~d Water Quality sources through State and Federal efforts looks promising; however, the water quality of Panhandle rivers is presently most affected by out-of-state pollution. Any improvements in this problem will result from either improvement in the regulatory programs of Alabama and Georgia or efforts by Federal authorities. The State of Florida has been carrying on negotiations with these Statesfor several years in an efforts to encourage their help. The outlook for control of nonpoint-source pollutants is not as promising. Nonpoint-source pollution is generally the result of rainfall runoff carrying dilute amountsof polluting agents such as petroleum products and nutrients. Since ~noff almost invariably increases with development, nonpoint-source pollution also increases with development. The problemswith nonpoint-source pollution havelessto do with the concentration of the pollutants in the runoff than with the total pollutant load that iscarried to our waters each year by the enormous volume of rainfall that runs off the Panhandle. The impacts of this type of pollution tend to be less noticeable than those of point sources because they lack the localized nature of the sometimes massive effects which bring apoint-source sitetothe attentionof the public. The nonpoint-sourcepollutantsareneverthelessimportant and their area of effect often widespread. Detecting and preventing their proliferation will require that regulating agencies establish baseline and monitoring biological and chemical studies in area waters and that future development be planned and controlled to minimize creation of nonpointsource Dollution. bodies to be affected. The Panhandle seems to be receiving rainfall that is more acidic than the rest of thestate receivesexceptforthe area immediately to the east. Metal-containing sediments are a possible source of water quality problems. Some anaerobic sediments have been identified as potential sources of heavy metal pollution. When iron and sulfur are present in anaerobic sediments (they are especially common in marine sediments) pyrite is formed. When disturbed and exposed to aerobic conditions (e.g., dredging and disposal of resulting spoil), the pyrites rapidly oxidize, forming sulfuric acid. Interstitial porewater pH's as low as 2-3 occur and these conditions can release substantial quantities of any metals bound in the sediments into surrounding waters. This problem has been Identified in European harbors (harbor sediments commonly have substantial metal loads [FDER 1986b1) and its potential is being investigated in the Mississippi delta. Possible Panhandle sites where this could be a problem include Pensacola Bay, Apalachicola Bay, and the Dead Lakes along the Apalachicola River. b. Ground water. The single greatest concern for ground water is contamination from landfills. Panhandle ground-water supplies are very easily contaminated by toxic substances percolating from the surface through the porous ground. With growth comes the necessity of disposing of increasing amounts of waste. Many old landfills were established without regard to their potential for groundwater contaminatlon. These must be located and, where necessary, closed and their contents disrain is potentially damaging to the surface posed of safely. New landfills and other forms of waters of parts of the panhandle. studies are Surface disposal must be established and managed presently underway to determine the sources, prevent Of ground water. amounts, and effects of acid rain (Environmental Science and Engineering, Inc. 1982a, 1982b, 1984; FDER and Florida Public Service Commission 1984; FDER 1985b). Preliminary findings suggest that acid rain results from sulfate emissions by powerplants and other industry, that it tends to be concentrated over land by the sea-breezelland-breeze phenomenon, and that it develops most strongly during the summer when it is transported northward by the prevailing winds. The already acidic and unbuffered streams and lakes formed by swamp drainage are probably the most likely surface water The intrusion of saline ground water into the potable aquifers is the second greatest future problem. The increasing consumption of ground-water supplies by agrowingpopulationwillcausethisto be increasingly common. Historically in south Florida, this type of water problem was addressed by local governments with temporary improvements which were not cures and which often simply increased the size of the area of saline contamination, Comprehensive plans have not been instituted until the situation bordered on collapse. In the western Panhandle a water distribution system to prevent
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Panhandle Ecologicr 11 Characterization this nearly irreversible contamination needs to be instituted before the intmsion increases. Degraded water quality may occur in Panhandle areas where ground water is pumped for irrigation. The water in excess of plant needs percolates back throughthe groundtothe shallow aquiferfromwhich it was pumped, carrying residual concentrations of the fertilizers used on the crops. It is pumped and used repeatedly and the fertilizer residuals tend to increase in the aquifer. The constant percolation increases the porosity of the ground, minimizing the time before more irrigation is necessary and therefore speeding the cycle. As a result of this process, places in west-central Florida south of Weeki Wachee are unfit forfarming. Care must be taken in areas where this recycling might occur to limit irrigation to levels necessaryfor good crop growth, thereby minimizing the amount percolating back to the underlying ground water. The direct forms of waste water disposal to the aquifers (e.g., drainage wells and injection wells) which are being used must be investigated carefully and institutedwithgreatcaution. Theoppoltunity for large scale pollution of ground water with these methods is very real. The problems of thefuture sternlargely fromthe need to balance the pressure for "progress" against the maintenance of those factors necessaly to support that progress. Given the near inevitability of the growth, it is sensible to pay extra attention to maintaining the ecosystem.
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Chapter 5. TERRESTRIAL HABITATS 5.1 Introduction Animals and plants are directly affected by the physical nature of the environment. All of Florida's habitats can be ordinated along one or more physical gradients. Among the most important are (I) slope. (2) soil moisture, (3) soil particle size, (4) soil pH. (5) fire frequency, (6) stream order (e.g., Strahler 1964), (7) temperature, (8) light intensity, (9) duration of inundation, and (10) humidity. Each physical factor varies in intensity or quality, often determining the presence, absence, or numbers of individuals in a species population. Groups of species can be found together in a community or habitat more or less predictably over a geographic region, wherever the same physical aspects of the environment occur. The plant communities that develop in response to background physical and chemical conditions are integrating links between the watershed as a physical unit and the watershed as a habitat for fish and wildlife. Plants and animals possess a wide variety of adaptive mechanisms to reduce competition with one another and for responding to changes in their localenvironment. They may inturn inducechanges in their surroundings that shift the competitive balance in their favor and lead to the succession of one community into another. In plants, such changes include the production of flammable plant parts to promote the probability of fire (Mutch 1970). the production of secondary plant compounds that inhibit the growth of other plant species (allelopathy), local control of microclimate, local erosion control. the alteration of topographic patterns, and the accumulation and recycling of organic matter, as well as many others. In animals, such changes include ailering the environment by their behavior such as territoriality, grazing, burrowing, or excavating holes in trees. The outcome of all these interactions is that biotic communities are dynamic rather than static systems. The watersheds of Panhandle Florida, because of their unique geographical position and geological and hydrological history, have a diverse array of habitatssupporting avariety of vegetative communities. Bottomland hardwoods predominate in the river floodplains, and pines mixed with a variety of other tree species and shrubs prevail in the uplands. Wetlands dominate the coastal fringe of the bay systems and large parts of the river floodplains. Dune vegetation and salt marshes are common and important habitats of the barrier islands, beaches, and spits that borderthe coastline. Seagrass meadows and oyster reefs provide habitat diversity to the intertidal and subtidal areas within the bays. For more than 400 years northern Florida has been explored by naturalists. Some of the reports and writings of the early naturalists (LeMoyne in DeBry 1591, Catesby 1743, Bartram 1791, Williams 1827, Muir 1917) provide numerous descriptions of plant species, but surprisingly few details01 habitats and community types. Although considerable surveys and obsewations have been made on the flora of the region, until recently a general lack of understanding of the delineation of plant communities and of the factors that control their structure, distribution, and successional relationships has prevailed. According to Clewell (1 971), the reasons for this lackof understanding include (1) the general complexity and diversity of Panhandle flora; (2) the subtle patterns of vegetation associations and the dramatic shifts that occur with little obvious change in physiochemical conditions; (3) the lack of information on the effectsof fire and flood onvegetation; and (4)the lack of information on the environmental tolerances and reproductive strategies of many important species. 19
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Panhandle Ecological Characterlzatlon Past and present land use also affect distributions. Although sparsely populated and industrialized compared to the rest of Florida, the watersheds of the Panhandle already have experienced severe environmental modifications affecting plant comrmnities and will continue to do so. Among the impacts are forestry, logging. agriculture, and land and waterway development for commerce and urbanization. Nonetheless, knowledge of the factors which affect the processes important for these communities is necessary to predict the future changes that will be induced by human alterations and provide information to employ proper management practices. The Panhandle is richly endowed with animals and plants. A general map of the distribution of vegetative communities (habitats) discussed is shown in Figure 59. Aquatic organisms, understandably, are limited in their geographic ranges by the continuity, or lack thereof, of the water in which they live. Therefore, all of the larger stream basins of Panhandle Florida have their aquatic endemics. Terrestrial animals and plants are not so limited by drainage divisions asthey are by water inthe stream courses of the drainage basin. Even so, numerous terrestrial species are restricted by, or at least have ranges terminating in, a specific Panhandle drainfound (Ward 1978). Table 7 lists the endangered or threatened animals (Wood 1986). 5.2 Native Habitats 5.2.1 Longleaf Clayhill Uplands Harper (1 906) recognized the biological dietinctiveness of the red hill country in the Coastal Plain of Georgia, calling it the Altamaha Grit Region. In Panhandle Florida, this same physiographic region reaches coastward from the Georgia border to its termination at Cody Scarp and is called the Tallahassee Red Hills (Harper 1914), a subdivision of the Northern Highlands (Puri and Vernon 1964). At least half of the terrestrial environments of Panhandle Florida are developedon redclay soilsof the Northern Highlands (Figure 59 and Figure 5). a. Flora. Longleaf pine (Pinuspalustris) wasthe principal tree species on upland soils (valley slopes and ridges) of the Coastal Plaln in pre-Columbian times. At least 70 million acres (Wahlenberg 1946) were reported to have supported longleaf, or yellow pine. Typically the canopy is sparse or open, allowingdirectorweaklyfiltered sunlight to the forest floor. This condition fosters a species-rich groundcover flora, containing more than 200 species of forbs and grasses per hectare (Clewell 1971, 1978). One age. grass particularly. pineland three awn, orwi;earass, Florida's richest region of endemicity is located in the Apalachicola Bluffs and Ravines, but other parts of the Panhandle have their own distinctive identities also. Between the Apalachicola and Ochlockonee Rivers, and between Telogia Creekon the north and the Gulf of Mexico on the south, lies another region of endemicity (Means 1977), and the vicinity of western Eglin Air Force Base seems also to beemerging asan area having narrowly restricted species, including a frog new to science (Rana okaloosae), a darter (Etheostoma okaloosae), a cyprinid minnow (Notropis new species), possibly a desmognathine salamander, the Panhandle lily (~ristida stricta).is a groundcover dominant that is always present. Other wiregrasses (Aristida spp., Sporobolus spp. and bluesterns Andropogon spp.) are common herbs, and bracken fern (Pteridium aquilinum) is always present and often abundant. Forbs include numerous species of composites (Aster spp., Eupator~um spp., Solidago spp., etc.), legumes (Desmodium spp.. Lespedeza spp., Tephrosiaspp., etc.), and heaths (Vacciniumspp., Gaylussaciaspp.). Woody low shrubs such as the runner oaks (Ouercus pumila and 0. minima), chinquapin, (Castanea pumila), and others are common. See Clewell (1978) for a full list of the plants found on three longleaf clayhill habitats near Thomasville. (Lilium iridollae), and others. Georgia. On rid~es and hiqh slo~es in clavhill couniry where ralis have leached clays from-the Table 6 lists all the known Panhandle endantopsoil, the scrub oaks Ouercus laevis, 0. marilandgered, threatened or commercially exploited plants ica, and 0. incana are found. These were suplisted by the State of Florida and USFWS (Wood pressed by the frequent natural fires of these com1986) and the Panhandle counties inwhich they are munities in pre-Columbian times, and occurred
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Panhandle Ecological Characterlzatlon Table6. Panhandle Plants listed as Endangered (E), Threatened (T), Commercially Explolted (C), and Under Review (UR) by the State of Florida (FDA) and USNVS (from Wood 1986) and countles where they are found (from Ward 1978). (continued) 112
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5. TerIe81IlaI Habitats Table 6. Concluded
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Panhandle Ecologlcal Characterlzatlon Table7. Vertebrateanlmalsof Panhandle Florldawhosestatus isthreatened (T),endangered (E), under revlew (UR), or of speclal concern (SSC) (after Wood 1986). Status Sclenllflc name Common name State Federal Fish Acipenser oxyrhynchus desotoi Atlantic sturgeon Ammocrypta asprella Crystal darter Etheostoma histrio Harlequin darter Etheostoma okabosae Okaloosa darter Fundulus jenkinsi Saltmarsh topminnow Micropterus notius Suwannee bass Micropterus sp. (undescribed) Shoal bass Notropis callitaenia Bluestripe shiner Notropis sp. (undescribed) Blackmouth shiner SSC UR T UR SSC E E SSC SSC SSC SSC UR E UR Amphibians Ambystoma cingulatum Flatwoods salamander UR Haideotriton wallacei Georgia blind salamander UR Hyla andersonii Pine barrens treefrog SSC Rana areolata Gopher frog SSC UR Rana okaloosae Bog frog SSC UR Reptiles Alligator mississippiensis American alligator SSC T (SIA)a Caretta caretta caretta Atlantic loggerhead turtle T T Chrysemys (=Pseudemys) concinna Suwannee cooter SSC UR suwanniensis Dermochelys coriacea Leatherback turtle E E Drymarchon corais couperl Eastern indigo snake T T Gopherus polyphemus Gopher tortoise SSC UR Graptemys barbour; Barbours map turtle SSC UR Lepidochelys kempii Atlantic ridley turtle E E Macroclemys temmincki Alligator snapping turtle SSC UR Pituophis melanoleucus mugitus Florida pine snake SSC UR Blrds Airnophila aestivalis Bachman's sparrow UR Ammodramus maritimus juncicolus Wakulla seaside sparrow SSC UR Aramus guarauna Limpkin SSC (continued) 114
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5. Terrestrial Habitats Table 7. Continued Status Sclentlflc Name Common Name State Federal Birds (contlnued) Buteo swainsoni Swainson's hawk UR Campephilus principalis Ivory-billed woodpecker E E Charadrius alexandrinus lenuirostris Southeastern snowy plover T UR Charadrius melodus Piping plover T T Cistothorus palustris marianae Marian's marsh wren SSC Dendroica dominica stoddardi Stoddard's yellow-throated warbler UR Dendroica kirtlandii Kiriland's warbler E E Egretta caerulea Little blue heron SSC Egrefta thula Snowy egret SSC Egretfa tricolor Tricolored heron SSC Elanoides forficatus Swallow-tailed kite UR Falco peregrinus tundrius Arctic peregrine falcon E T Falco sparverius paulus Southeastern kestrel T UR GNS canadensis pratensis Florida sandhill crane T Haematopus palliatus American oystercatcher SSC Haliaeetus leucocephalus Bald eagle T E Lanius ludovicianus migrans Migrant loggerhead shrike UR Mycferia americana Wood stork E E Pelecanus occidentalis Brown pellcan SSC Picoides borealis Red-cockaded woodpecker T E Rostrhamus soc~abtlrs Snail kite E E Sterna antillarum Least tern T Vermivora bachmanii Bachman's warbler E E Mammals Felis concolor coryi Mustela vison lutensis Myotis austroriparius Myotis grisescens Myotis sodalis Neofiber alleni Peromyscus floridanus Peromyscus polionotus allophrys Peromyscus polionotus leucocephalus Peromyscus polionotus peninsularis Peromyscus polionotus trissyllepsis Plecolus rafinesquii -Florida panther E E Florida mink UR Southeastern bat UR Gray bat E E Indiana bat E E Round-tailed muskrat UR Florida mouse SSC UR Choctawhatchee beach mouse T E Santa Rosa beach mouse UR St. Andrews beach mouse UR Perdido Bay beach mouse E E southeastern blg-eared bat UR (continued) 115
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Panhandle Ecological Characterlzalion Table 7. Concluded Status Sclentlfic Name Common Name State Federal Mammals (contlnued) Tamias striatus Eastem chipmunk SSC Trichechus manatus latirostrrs West Indian manatee E E Ursus americanus floridanus Florida black bear T UR =S/A = similarity of appearance mostly as woody herbs in the groundcover. At best they were small trees of the understory, probably rarely attaining 30 years of age. The second-growth forests of this community type today are somewhat different from their presettlement prototypes in several important ways. First, the ageclass composition of clayhill longleaf forests is truncated: most stands are less than 60 years old, containing no trees 350-400 years old as is possible for longleaf pine (Wahlenberg 1946). Second, the cycle of summer fires has been halted or, in the case of controlled burning, shifted to winter burns. Alteration of the firecycle has had adramatic effect upon the reproduction of many of the species of plants in longleaf communities. Because many plants require fires in summerto stimulate flowering (Parrotl 1967, Davis 1985, Means and Grow 1985). the absenceof fireorthe shiftingolfire to the season of plant dormancy has prevented these species from reproducing. Moreover, many of these same species, and others that do not require summer fires for flowering, have vastly diminished recruitment because their seeds require a bare mineral soil on which to germinate. Longleaf pine itself has this requirement; summer burns open the rank groundcover and create bare mineral soil which lies exposed when longleaf seeds normally fall to the ground during fall and winter. b. Ecology. The life cycle of the longleaf pine is important to the ecology of the clayhills, sandhills, and flatwoods ecosystems it inhabits and will be discussed to provide an understanding of the functioning of these ecosystems. Even though fully grown specimensof most of the species of southern pines can withstand fire, they are killed in the seedling and sapling stage. Longleaf pine alone, IS physically adapted to tolerate fire when young. Instead of growing upward right away as most saplings do, longleaf seedlings stay flat on the ground for periods of 3 to 15 years (Croker and Boyer 1975) During the "grass stage,"the young tree grows a long, heavy taproot that probably helps it reach far down into the sandy soil toward moisture; this tap root also serves as a nutrient storage organ. When the young plant finally starts to grow tall, the stored food in the taproot helps it shoot rapidly upward. At the same time that it is racing skyward, the tree delays putting out branches, giving young saplings of this species adistinctive bottlebrush appearance. By growing rapidly upward in a single spurl, the young tree minimizes the amount of time its growing tip is vulnerable to destruction by ground fires. A young tree growing steadily year by year and putting out multiple brancheswould bevulnerabletoground fires over a far longer period of time. Moreover, longleaf pines have thick, corky bark and dense tufts of needles surrounding its apical buds. These two characteristics insulate the young longleaf pine and are obvious adaptations for resisting heat. Like many conifers, the seeds of the longleaf require open sunlight and bare mineral soil on which to germinate. Beneath longleaf pines, however, the ground isdensely carpeted with wiregrass and many other native grasses and forbs. The only open places readily available to longleaf seeds are very small bare patches of soil created by burrowing animals (e.g., gopher tortoise, Gopherus polyphemus; pocket gopher, Geomyspinetus) and the tip-up
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5. Terrestrial Habitats mounds of wlnd-thrown longleaf trees. More than the present generations of longleaf pines are desany other single agent, is fire that creates the bare tined to be harvested when their commercial value mineral soil conditions necessary for the germination of longleaf seeds. In the longleaf pine be&, summertime is the season of natural fires. The pines drop their seeds in the autumn and those seeds germinate when otherplantsare dormant from October to March, a timing that is adapted to the yearly cycle of the fires. The periodicity of natural fires depends mainly upon two major factors: (I) number of local lightning ignitions, and (2) the occurrence of broad, sweeping fires. It is obvious that summers with more lightning storms also had more fires. The amount of lightning, however, varies considerably from summer to summer, as meteorological data for the past halfcentury show. About once every decade, summer lightning reaches a peak. During those peak summers, there are enough lightning storms to set enough local fires to burn off most of the longleaf pine sites in the Coastal Plain. There is good reason to believe that the original longleaf forests typically burned every 2 to 3 years, but sometimes they burned annually and, during periodsof low lightning incidence and wet summers, sometimes as seldom as once in 5 years (Clewell 1971, Means and Grow 1985, Christensen, in press) Lightning is usually attracted to older, larger pines. Older pines are more likely to have heart-rot, afungal infection that makes the heartwood porous andmoreflammable, andto have more resinsintheir heartwood than youngertrees. Even when alive, the older trees are more likely than younger trees to be set afire,orto beset smouldering, evenduring heavy rains. A smouldering tree can ignite a ground fire days later, when the storm is past and the ground is dry again. Dead trees may start groundfires more readily than live onesdo. The original longleaf forest not only was able to survive fire, it even depended upon fire, and it may actually have helped start and sustain the fires that regularly burned it (Mutch 1970). Old-growth trees-living or dead-are exceedingly rare in the Coastal Plain today because almost all of the original timber has been cut. Furthermore, peaks out at 40-50 years, and there will be very few forests, indeed, that contain old longleaf pines, living or dead. In the original forests of the Coastal Plain, longleaf communities dominated the uplands and spread downslope from ridgetops all the way to the saturated soils. Longleaf pine forests have been labeled as fire "disclimax" or "subclimax" forest, because, to survive, they need fires to suppress the scrub oaks and other hardwoods that would otherwise take over. Most hardwoods are thin barked and fire tender, and in the original forests, they could only survive in the Coastal Plain in areas that were naturally fire protected, such as valley bottoms and lower down on the moist soils of valley sidewalls. There still are many places where the pine woods grade naturally into the hardwoods As one travels downslope from the dry uplands, the first hardwoods one sees are typically shrubby, smallleaved evergreen species. Further downslope, these grade into more substantial hardwood trees at the toe of the valley sidewall and thereafter, the species composition changes according to the hydrology of the stream course. c. Soils. The soils of the clayhills are developed from the M~ocene Mlccosukee Formation In the Tallahassee Red H~llssubd~vis~on of the Northern Highlands, and from the Citronelle Formation in the western Highlands. Clayhills soils tend to hold moisture over a long period of time. On ridgetops, rain leaches the clay particles from the top 6 inches of soil, creating sllghtly more xeric soil conditionsfor plants and animals. Hilltops are the sites in the clayhills communities of the Tallahassee Red Hills, Grand Rldge, New Hope Ridge, and the Western Red Hills where the best agricultural lands lie, and the lands that have been most impacted by agriculture and development. d. TrOphlC dynamics. Anhough no measures have been found in the literature, the primaty pmductivity in longleaf clayhill associations is probably about equally dlvided between the overstory and the groundcover. Primary consumers of the longleaf
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Panhandle Ecologlcal Characterlzstlon pines are mostly insects, but there is some consumption of young longleaf seedlings and saplings by grazing and browsing vertebrates. Feral hogs are known to be particularly damaging to young longleaf pines by digging and eating the long tap roots. (Wahlenberg 1946). The high primary productivity and species richness of the plants support a rich consumer community. In addition to leaf-, stem-, and root-consuming insects (i.e., lepidoptera, orthoptera, wleoptera, diptera, hemiptera) and other invertebrates, the many species of flowering forbs attract numerous species of pollinating insects. Because the groundcover plants bring their insect consumers close to the ground surface, insectivores abound there and include predaceous beetles (coleoptera), dragonflies (odonata), bugs (hemiptera), mantises (mantida), and spiders (arachnida). The invertebrates are also the food base for dozens of vertebrate insectivores including lizards, frogs, mammals and birds. e. Fauna. The following animals are principal species found in open, longleaf pine forests: redtailed hawk (Buteo jamaicensis), great horned owl (Bubo virginianus), fox squirrel (Sciurus nigef), eastern diamondback rattlesnake (Crotalus adamanteus), pine snake (Pituophis melanoleucus), gopher tortoise (Gopherus polyphemus), Bachman's sparrow (Aimophila aestivalis), and bobwhite (Colinus virginianus). In a drift-fence study of the amphibians and reptiles inhabiting a 200-acre tract of old growth longleaf pine in the Tallahassee Red Hilts (Means and Campbell 1981), 20 different species were recorded in over 6,000 trap weeks during one 2-year period (Table 8). Engstrom (1982) reported the largest number of breeding birds from any known Florida habitat from the same site (Table 9). 1. Rare and endangered species. Panhandle Florida longleaf clayhill communities support a large numberof species that are rare, endangered, threatened, or of special concern. The gopher tortoise, a species of special concern, is found in clayhills from the Perdido to the Ochlockonee drainages. but does not do as well in clayey soils as does in sandy soils. The gopher tortoise is a keystone species (Eisenberg 1983) whose presence is vital to the existence of other species. The burrows of the gophertortoise are a haven for dozens of vertebrates and invertebrates, including a few strict obligate commensals that are totally dependent upon the gopher tortoise. More about the interdependencies of the tortoise and its commensals is discussed under sandhills habitat. The federally endangered red-cockaded woodpecker (Picoides borealis) once was common in clayhills longleaf forests, but most of the native longleafforest has been replaced inclayhills habitats by the mixed shortleaf-loblolly pine hardwood community in which the red-cockaded woodpecker does very poorly. Mature longleaf pine forests such as those that originally clothed the clayhills habitats of the Northern Highlands are nearly nonexistent today. Their absence is the principal reason why the red-cockadedwoodpecker is endangered. Because so much of the original longleaf pine clayhills communities have been converted into ruderal communities, the native biota of longleaf clayhills has been severely reduced or fragmented. 5.2.2 Longleaf Sandhill Uplands The term "sandhills" has been applied to this community by a long list of its students (Laessle 1958. Bozeman 1971, Campbell and Christman 1982, Means and Campbell 1981, Christensen in press). Mher common names that have been applied to this community are high pinelands (Cleweli 1971), longleaf pine, and xerophytic oaks (Davis 1967), and dwarf oak forests (Wharton 1977). In Panhandle Florida, sandhills habitats can be roughly classed into two types: (1) the longleaf sandhilt uplands in the interior, especially those occurring as a broad band of deep sand deposits below Cody Scarp, including Eglin Air Force Base, Greenhead Slope. Fountain Slope, and Beacon Slope; and (2) sandhills along the mast that are vegetated with coastal scrub vegetation (overstory of either slash pines or sand pine, and understory of coastal scrub oaks). The former are discussed here, the latter in 5.2.7. a. Solls. The well-drained white-to-yellowish sands usually are 100 cm (40 inches) or more deep above finer textured subsoils. They are relatively sterile, nearly flat to strongly sloping, acidic, moderately to excessively well drained, and coarsely textured. Water moves so rapidly through the soil that shortly after rains and in the interim between
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5. Terrestrial Habitats Tabie8. Numbers of amphibians and reptiles captured on two annually burned pine stands and an unburned hardwood stand In north Florida (Means and Carn~bell1981). Longleaf pine Shortleaf lobBeech Species clayhlllsm lolly clayhillsb magnolias Ambysoma opacum 0 3 264 Ambystoma talpoideum 0 0 22 Ambystoma tigrinurn 99 13 0 Notophthalmus viridescens 4 0 1 Eurycea bislineata 0 0 1 Eurycea quadridQitata 1 0 0 Plethodon g~ut~nosus 0 3 18 Scaphiopus holbrooki 41 21 24 Bufo quercicus 294 0 0 Bufo terrestris 38 66 28 Acris gryllus 0 0 8 Hyla cinerea O 22 Hyla crucifer 2 Hyla gratiosa 2 0 0 Hyla chrysocelis 0 0 1 Pseudacris nigrita 3 0 0 Pseudacris ornata 152 0 0 Rana catesbeiana 0 3 2 Rana clamitans 0 1 6 Rana sphenocephala 4 4 9 Gastrophtyne carolinensis 39 22 20 Kinosternon subrubrum 3 0 0 Terrapene carolina 3 1 0 Deirochelys reticularia 2 0 0 Anol~s carolinensis 0 2 12 Sceloporus undulatus 0 3 0 Cnemidophorus sexlineatus 16 2 4 Eumeces inexpectatus 2 0 0 Eumeces laticeps 7 14 2 Leilopisma laterale 0 0 Ophisaurus ventralis 7 0 ACemophora coccinea 2 0 Coluber constrictor 0 0 Elaphe gunata 0 1 EElaphe obsoleta 0 0 Heterodon pbtyrhinos 0 1 0 Thamnophis sauritus 2 0 0Thamnophis sirtalis 0 4 0 Total 721 164 430 Total number s~ecles 20 17 21 '64 traps running continously 16 March 197Feb 1981 = 6,272 trap weeks. b16 traps running wntinously (except 11 Apr-24 Sep 1978) 1 Feb 1976-6 Feb 1981 = 2,760 trap weeks. =3 traps running wntinously 14 Apr 197618 Apr 1978, then 16 traps 12 Oct 1978-6 Feb 1981 = 1,840 trap weeks.
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Panhandle Ecological Characterlratlon Table 9. Breeding blrds of clayhili longleaf old-growth forest (from Engstrom 1982). The number of individuals per trip in Wlnter Blrd Population Study (WBPS-79,58.3 ha), the number of breeding pairs pertract in Breeding Blrd Censuses (BBG79,58.3 ha; BBCBO, 20 ha), and resldency status. Specles WBPS-79' BBC-79 BBC-80 statusb Wood duck (Aix sponsa) + 2 2 WE Bobwhite (Colinus viginianus) 2.5 2.5 BO Mourning dove (Zenaida macroura) 2 10.5 3 WE Great horned owl (Bubo virginianus) 1 1 WE Common flicker (Colaptes auratus) 4 5 1.5 WE Pileated woodpecker (Dryocopus pileatus) + 1 + w!L Red-bellied woodpecker (Melanerpes carolinus) 8 8.5 3.5 WE Red-headed woodpecker (M. erythrocephalus) 13.5 3.5 BO Yellow-bellied sa sucker (Sphyra icus varius) 3 w! Red-cockaded w:odpecker (Picozes borealis) 17 5 1.5 WB Hairy woodpecker (Picoides villosus) + 1 1 WB Downy woodpecker (Picoides pubescens) + l+ WE Eastern kingbird (Tyrannus tyrannus) 3 + B Great crested flycatcher (Myiarchus crinitus) 13 4 B Eastern wood pewee (Contopus virens) 8.5 4.5 B Blue jay (Cyanocitta cristara) 2 8 2 WB Common crow (Corvus brachyrhynchos) 2 WE Tufted titmouse (Parus bicolor) 1 WB White-breasted nuthatch (Sitta carolinensis) 7 5 2.5 WE Brown-headed nuthatch (Sitta pusilla) 7 7 4.5 WB House wren (Troglodytes aedon) 9 W Carolina wren (Thryothorus ludovicianus) 4 4 2.5 WE Nolthern mockingbird (Mimus polyglottos) 1 BO Brown thrasher (Toxostoma rufum) 3-I BO American robin (Turdus americanus) 8 W Eastern bluebird (Sialia sialis) 3 3 2 WB Loggerhead shrike (Lanius ludovidianus)_ 1 1 + WB Solitary vireo (Vireo solitarius) 2 W Yellow-throated vireo (Vireo flavifrons) 1.5 + B Yellow-rumped warbler (Dendroica coronafa) 2 W Pine warbler (Dendroica pinus) 11 10 6.5 WB Palm wafbler (Dendroica palmarum) 2 W Common yellowthroat (Geothlpis trichas) 12 14 4.5 WE Yellow-breasted chat (Icteria virens) 11.5 2.5 B Eastern meadowlark (Sturnella magna) 5 7.5 3 WE Red-winged blackbird (Agelaius phoenicus) 60 2 WB Common grackle (Quiscalus quicala) 1 BO Brown-headed cowbird (Molothrus ater) 5 4 BO Orchard oriole (Icterus spurius) 2 1 B (continued) 120
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Panhandle Ecologlc grow, and the absence of fire provides them the opportunity they need. Stems sprout, new stems grow, leaves proliferate, and trees shoot up into the bright sunlight between the widely spaced pines. Normally, fires kill this growth back every few years. But when there are no fires, the oaks keep growing until their branches touch to form a closed canopy. The ground under dense scrub oaks is shaded from light and covered with leaf liner. Longleaf seeds and seedlings cannot sprout there. Without fire to remove the oaks, the towering longleaf is conquered by a mass of scrub oaks. Carried to the extreme by selective logging or long-term fire exclusion, the big pines die of age, no little ones replace them, and the prolific scrub oaks inherit the forest. There is good reason to believe that natural fires kept the scruboaks undertight control in theoriginal longleaf forests, pruning them back, keeping most of them as small shrubs, and some no bigger than herbs. Photographsof virgin longleaf sites attheturn of the century corroborate this, as do recent experiments in control burning. All over the Coastal Plain today there are dense, 30 ft high stands of scrub oaks, which took over after people cut the longleaf pines and disrupted natural fires. In essence, those sc~b oak forests are a human creation. d. Fauna. The fauna of the sandhills communitiesof Panhandle Florida have not been studied per se. and what is known about sandhills ecoloav almost 40 commensal species of vertebrates and invertebrates. Many of these species are obligate commensals, requiring tortoise burrows for their survival. Some have been associated with the gopher tortoise burrows so long that they have become partly cave-adapted, losing pigment. A threatened species, the indigo snake (Drymarchon corais), is heavily dependent upon gopher burrows, as is the gopher frog, whose common name reflects its dependence upon the gopher tortoise, and possibly the pine snake. Other notable vertebrate animals occurring in Panhandle sandhills are the eastern spadefoot toad (Scaphiopus holbrookir), ens of the newt (Notophthalmus viridescens), eastern tiger salamander (Ambystoma tigrinum), eastern diamondback rattlesnake, six-lined racerunner (Cnemidophorus sexlineatus), southern fence lizard (Sceloporus undulatus), fox squirrel, old field mouse (Perornyscus polionofus), cotton mouse (P. gossypinus), short-tailed shrew (Blarina brevicauda), mole (Scalopus aquaficus), least shrew (Cryptodus panla), cotton rat (Sigmodon hispidus), cottontail (Sylvilagus floridanus), and numerous other species that occur over a wide range of habitats. Significant rare, endangered, or threatened species are red-cockaded woodpecker, gopher tortoise, indigo snake (Drymarchon corais), pine snake, and gopher frog. See Table 7 for status details. comes mostly fromstudies located incentral ~lorida. There, a well developed endemic fauna exists, in5'2.3 Gully-eroded Ravines cluding half adozenor more vertebrates. It appears Small first and second order (Strahler 1964 that the fauna of the panhandle sandhills is de,-,auclassification) streams with steepvalley walls have a peratewhencomparedtocentral Florida. NeveiheUnique physiography and microclimate and should less, there areanimalsthat flourish inthe Panhandle be recognized as a separate community type in the sandhills that are not generally found in other habi. Panhandle, considering their extensive occurrence. tats, ~h~~~ are the re,j-tailed skink (E~~~~~~ egreThe valley floors of such streams are wetlands, quite pius), gopher frog (Rana areolata), pine snake, and different invegetation, hydrology, andfaunairomthe pocket gopher. valley slope beginning at a sometimes sharply defined toe. Many of Florida's rarest animals and ~h~ gopher by most plants, as well as numerous endemics and relicts, Coastal Plains States as threatened or a species of Occur in ravines. special concern (State of Florida), is the most important native grazing animal in the pineland forests it a. Soils. Mostofthegully erodedstreamvalleys inhabits. It is a keystone species whose extirpation in the Panhandle were developed in the Hawthorn, would havedire wnsequencesforawhole communMiccosukee, and Citronelle Formations of the Northity of otheranimals. The long and persistent gopher ern Highlands and, as a consequence, soils of the burrows excavated by tortoises are homes for up to valley sidewalls are coarse elastics, usually sand,
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5. Terreatrlal Habltata clayey sand, or sandy clay, well drained, and moderately-to-steeply sloping. Occasionally Tertiary limestones are exposed and the stream channel may even be etched into hard limestone bedrock (as above Aspalaga Landing onthe Apalachicola River). The soils of the stream valley bottom in its first and second order (Figure 60) reaches are eroding and are composed of the same materials of the valley sidewalls immediately upslope. Soils of the floodplain of the third and higher orders are alluvial, contain more silts and clays, and are distinguished by the presence of partially decomposed vegetation in the form of fluid muck or fibrous peat. b. Ecology. Rainwaterworks its way to the sea by (1) evaporation off the land surface and direct transport to the sea via precipitation: (2) by percolation downward and seaward through underground passageways ranging in size from the interstitla1 spaces between sand or clay particles to 30-m diametertunnelsdissolved in limestone; and (3) over the top of the ground as surface runoff. This latter means by which water moves tothe sea is extremely important to plants and animals because the erosive power of surface runoff sculpts the physical topography of the land. Where soil particle size (clays and sib) IS so small as not to allow much percolation, surface runoff is proportionally higher than where soils are coarser grained and more friable. Gullying of the land surface, therefore, is more extensive in tighter soils. The tightly packed soilsof the Western Highlands, Grand Ridge, New Hope Ridge, and the Tallahassee Red Hills physiographic regions are the most susceptible to gullying of all the Panhandle soils. Combined with the greatest elevations in the Panhandle, the highlands contain some of the most deeply entrenched ravine valleys in Florida. Gullyeroded ravines are most abundant and deepest along the valley wall escarpments of the larger river systems. Those along the eastern valley wall of the Apalachicola River are among the vely best examples of deeply incised small-tributary ravine valleys in the entire Coastal Plain, and have been famous the worldoverfortheir biological uniqueness for 140 years (Gray 1846, James 1961, Graham 1964). The Apalachicola Bluffs and Ravines area is recognized as biologically distinct (Means 1977, 1985C). Other ravines in the Northern Highlands are clustered alongthe HolmesValley Scarp(see Figure Habitat Gradient Figure 60. Stream habltat classlflcation (Strahler 1964): (1) order 1 streams including gully erosion (Vshaped) and steephead (U-shaped) ravines: (2) order 2 streams: (3) order 3 streams; (4) order 4 streams; (5) order 5 streams; (6) streams greater than order 5, but less than about order 8; (7) large river floodplain sloughs and alluvial swamp habitats; (8) lake and pond margins.
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Panhandle Ecological Characterlzatlon 5), along parts of the southern and western valley wall of the Choctawhatchee River, along the southwestern valley escarpment of the Escambia River, the western tributaries of the Escambia River, and along the Yellow River system and its majortributaries. All these ravinesystems are pooliy explored, but offer considerable promise of being biologically interesting (Means and Longden 1970; Means 1974a.b. 1975, 1985~). The heads of gully-eroded stream systems are hydrologically similar throughout the Panhandle. From catchment divides downslope for some distance, the water channels in catchment bottoms are subject to extreme fluctuations in streamflow. Typically, water flows only during and shortly after a rainfall. The persistence of flowing water is strictly dependent upon the regularity and amount of rainfall. During normal dry periods and particularly during extendeddrought, these streamchannels are quite dry, and are inhospitable to aquaticorwetland plants and wildlife. At some point down the stream gradient, the moisture in the catchment soils upslope becomes great enough, notwithstanding the relatively impermeable clay soils, to slowly leak into the stream bottom, creating a more mesic to hydric condition. Thisusually is along portions of the creekgradient of Strahler order 2 or 3 (Figure 60). During a drought. even in these reaches streamflow dries up, but the soil moisture remains high enough to support a wetland vegetation of evergreen shrubs and hardwoods. These parts of headwater catchments are clearly erosional, showing linle alluviation in the valley bottom, and having relatively steep valley sidewalls. Further downstream, when the slope of the stream bottom becomes shallower, stream flow slows down and loses its scouring ability. The stream drags its sediments along and spreads them all over the valley bonom (alluviation), creating a more or less flat surface with minordepressions. A low-water channel develops that carries stream water during low water stages, but during heavy rains, the water risesout of the meanderingchannel andflowsovertheentireflat surfaceofthefloodplain. Whenthe water recedes, it istrapped in the shallow basins where partially decomposed organic debris builds up as muck or peat. This portion of the Strahlergradient ischaracterlzed by a stream channel incised into the floodplain floor with clayeysandy-organic banks that rise sometimes 2 to 3 fi above the channel bed. During dry weather the alluvial portions of ravine streams are mesic, and suppolt many of the members of the beech-magnolia community. During wet weather, however, water flows or stands in the floodplain long enough that a numberof hydrictreesottenarefound here too. One value of gully-eroded ravines is to preserve the terrestrial habitat gradient from longleaf pine clayhills to beech-magnolia mesic forest. Where slopes are gentle, ravines are not present because people have replaced the natural forest types with agriculture, silviculture, and urban and suburban developments. The steep slopes of ravine valleys preserve some of the natural terrestrial communities trom gross alteration by human activities. Ravines also have a higher and more continuous humidity during summer because ofthe greenhouse effect underthe closed canopies and confining valley sidewalls of ravines. The variety in slope shading, results in north-facing effects (protection from direct sunfall), south facing effects (dryer microclimates because of moredirect year-round sunfall), and combinationsof these. c. Flora. Generally, the lower valley sidewalls support a beech-magnolia community (see Section 5.2.5). In the saturated Soils of the alluvial floodplain on both sides of the stream channel, one finds hydric species such as the star anise (Illiclurn floridanurn), sweet bay magnolia (Magnolia virginiana), tulip tree (Liriodendron tulipifera), and sweetgum (Liquidambarstyraciflua). A classic example of a gully eroded ravine in reasonably undisturbedconditionis located just north of the city limits of Tallahassee. The gully-eroded Apalachicola ravines between Sweetwater Creek in Liberty County and the FloridaGeorgia border are replete with northern relicts and species endemic to the ravines. Leonard and Baker (1982) reported 52 species of trees, shrubs, and herbs that were endemics, relicts, or rare. d. Fauna. Wildlife that utilize gully eroded ravines include species tolerant of a wide range of moisture fluctuations. At the heads of gullies near the catchment divides, the vegetation and animal life are characteristic of the longleaf pine clayhills, but shortly downstreamwoody evergreenshmbspecies
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5. Tarrastrlal Habltats appear, then grade into the beech-magnolia forest the Citronelle Formation and in younger deposits with its characteristic wildlife (see sections on longbelow Cody Scarp (Puri and Vernon 1964, Brooks leaf pine clayhills and beech-magnolia forest). The 1981b) and are aligned east-west (Figure 61) in a stream itself is the beginning of a developing aquatic manner suggesting an old shoreline (Means 1981, gradient, and the water column has its own peculiar 1985~). wildlife associated with it (see Chapter 6.3.1). Steepheads and their stream valleys are formed The fauna of the uppermost reaches of gullywhen ground water leaks out on a sloping surface eroded ravines is typical of that found in the upland through porous sand at the head of a stream catc.,vegetation clothing the watershed (see longleaf ment. lf the volume of escaping ground water is clayhills and beech-magnolia sections). When soil substantial, sand will be carried away downstream, moisture increases, andgully-eroded StEi3mvalleYS creating a semicircular horizontal nick in the sloping begin to have some permanence of flow, a stream sand body. Overtime, as more sand is carried away, side litterfaunaisfound. The highly distinctivefauna a ~-~h~~~d (in vertical cross-section) valley forms of these streamsides features dozens of species of as the steep, ampt,ifiheatre-shaped valley head miinvertebrates found only in ravines, including earthgrates headward into the sand, lt is this process of worms (Diplocardia SPP., Sparganophilus SPP.), lateral sapping of the water table and the resulting crayfish (Procambarus spp.), trap-door spiders headward undercutting that makes steepheads and (C~clocOsmia torreYa), and Plethodontid salamanthe valleys they form fundamentally differem from ders (EurYcea bslineata, Pseudotriton Nber. Pietypical gully eroded stream valleys. Stream valleys thodonglutinosus, and Desmognathusspp.). When normally are formed as the surface of the land is studied systematically, the ravines across Panhancarried away by the scouring action of rainwater dle Florida should reveal a great deal of biological surface runoff, a process called gully erosion, diversity presently unrecognized. Steephead-originstreams are the same astheseepage streams listed by the Florida Natural Areas 5.2.4 Sleepheads Inventory. Steepheads are highly distinctive stream valley habitats (Means 1975,1981,1985~) known presentProceeding east across the Panhandle, steeply only from Florida, where they first were discoverheads first occur in the Panhandle inthe deepsands ed and named in the Panhandle (Sellards and of western Eglin Air Force Base. Large stream Gunter 1918). They are found in the deep sands of valleyscutdeeply intotheCitronellesandsthereand Figure 61. Distribution of known steepheads in the Florlda Panhandle (Means 1981). 125
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Panhandle Ecological Characterlzetion drain north into the lower reaches of the Yellow River, and south into East Bay River and Choctawhatchee Bay. A few have been etched into the landform along the eastern side of Econfina Creek in Washington County, and into sinkholes in norlhem Bay County. Below the main axis of Big Sweetwater Creek in Liberty County, every streamvalley feeding into Big Sweetwater Creek was formed by steephead migration, and eachstreamsupports a magnificent steephead that is still actively eroding its way headward. A few steepheads are found in the Telogia Creek drainage and along Ocklawaha and Bear creeks draining into the west side of Lake Talquin on the Ochlockonee River. Going east across north Florida, the last steepheads are found along the east side of Lake Talquin in the short tributaries etched into the western end of Beacon Slope. a. Soils. Soils of steephead valley slopes are exceedingly porous, coarse sands whose angle of repose is about 45". They are between 25 and 100 ft deep, depending upon geographical location. The soils of steephead valley bottoms are the same Citronelle and Recent sands of the valley walls, but have anoccasional veneerof organicdeposits along the stream margin and the lower, seepage slope of the valley wall. Downstream in thirdorder portions of steephead valleys, alluvial matter and organic sediments become more prevalent as substrates for plants and animals to live on, or burrow in. b. Ecology. The physical andchemical characteristics of steepheads are the result of their special hydrological conditions. Steephead waters are filtered through tons of sand, and emerge relatively neutral in pH. Waters of gully-eroded streamheads take on chemical characteristics of the substrate overwhich thewaters flow. Runoff waterscharacteristically are turbid with suspended clays and silts picked up from the parent material of the soil, and they contain leachates and organic particulates that sweep into the stream course. Since the porous sands soakup rainwater, there is little opportunity for sullace runoff to deliver organic or inorganic materials downslope into the stream. Steephead springs usually are continuously flowing, giving a perennial nature to the watercourse at and downstream from spring sources. The bottom of a steephead valley at its head can be up to 30 m deeperthan the top of the uplands it drains. Waterchemistry is not the only quality of steephead streams that is different from runoff stfeams. The temperature of steephead waters is thermally buffered because it emerges from subterranean perched aquifers. Steephead waters have ground-water temperaturesat alltimesof the year, butwarm up by ambient processes progressively downstream. Even so, the temperature of steepheadorigin streams such as Sweetwater Creek in Liberty County and Liveoak and Turtle Creeks in Okaloosa County are much cooler than the waters of surface runoff streams. Runoff waters are subject to considerable temperature fluctuation seasonally because of the airtem~erature on the catchment. but around watertendstotrack the annual average temperature of the surface of the ground; in the Panhandle, steephead spring-watertemperatures are 68-72 OF, year around. Because steepheads are highly localized phenomena and have formed de novo in each of the larger Panhandledrainages in which they arefound, they are rather isolated environments, separated by drainage divides upstream and by changing lotic environments downstream. Biologically, steepheads are natural laboratories providing a potential for ecological and evolutionary processes. Some populations of animals and plants in steepheads may differ from regional populations genetically because of the founder effect or strong local selection; populations of other species demonstrate ewlogical release in steepheads where more competitive congeners are precluded from immigration for some reason (Means 1975). c. Flora. Steepheads throughout the Panhandle generally possess a similar cross-sectional gradient of vegetation along a vertical transect running from the top of the basin or watershed they drain to the stream bed. Xeric longleaf pine-scrub oak (Pinuspalustrus, Quercus laevis, 0. incana, Q. mar;landica, and often Q. viginiana) communities are foundon drainage divides surrounding steepheads. From about where the crest of the slope breaks to about halfway down the transect, the forests are a closed-canopy assemblage of xeric, deciduous trees commonly containing Carya tornentosa, Quercus hemisphaerica, 0. nigra. In this xeric zone, are sometimes found stumps and cut logs-signs of a once more extensive occurrence of northern red cedar. Juniperus virginiana.
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About halfway down steephead slopes one enters a mesic forest containing many elements of the beech-magnolia climax type including Magnolia grandiflora, Fagus grandifolia, Ouercus nigra. Pinus glabra, Carya glabra, Ostrya virginiana, Querws michauxii, and 0. alba. In this zone in steepheads of the Apalachicola River basin, Magnolia pyramidata, M. ashei, and Stewarfia malacodendron also occur. On the lower one-third of steephead slopes that are protected from the sun (north-faces or particularly deep cuts), an evergreen shrub zone is developed This zone contains shrubby species such as Vaccinium arboreurn, Kalmia latifolia, Lyonia lucida, Rhododendron austrinum, and others. In steepheads of the Apalachicola River basin, the evergreen shrub zone is especially well-developed and contains many of Florida's endemic and rare northern plants. Among these are Kalmia latifolia, Rhododendron austrinum, Torreya taxifolia, Taxus floridana, Asarum arifolium, Croomia pauciflora, and others. The valley floor of steepheads is a wetland communly as demonstrated by an abrupt change to wetland plants and animals. lllicium floridanum and Magnolia virginiana are indicator species that are almost invariably found rooted in the inundated to saturated soils of steephead bottoms across the entire Panhandle. d. Fauna. The fauna of steepheads is mostly confined to the liter of the valley bonom, where a detrituscycling community of litter arthropods feeds a number of small vertebrates on the moist valley floor. Almost every steephead across the Panhandle supports breeding populations of three species of lungless salamanders of the family Plethodontidae. Two of these species are always found: the two-lined salamander, Eurycea bislineata, and the red salamander. Pseudotriton ruber. One of three species of dusky salamanders completes the trio: Desmognathus auriculatus is found in a few steepheads on Eglin Air Force Base and in the steepheads of Econfina Creek in Bay County; D. fuscus conanti is found in all others west of the Chipola River basin (Means 1974a.b). An undescribed species is endemic to the Apalachicola-chipola and Ochlockonee river basins (Karlin and Guttman 1986). The creek chub, Semotilus atromawlatus, often is found within a few meters of the sapping waters of steepheads when the volume is large as it is on Eglin Air Force Base. Downstream fromthesteephead proper, in streamsatthewestern end of Eglin Air Force Base, a frog new to science, Rana okaloosae, was just described as occurring in bogs along the margins of streams (Moler 1985). When Panhandle steepheads are thoroughly investigated, numerous relict or endemic invertebrates and possibly some nonvascular plants will be found. 5.2.5 Beech-Magnolia Climax Forests In the long-term absence of fire, hardwood forests eventually replace the fire-perpetuated longleaf pine ecosystemson all the uplandsoiis of Panhandle Florida. One particular association, in which American beech (Fagusgrandifolia) and southern magnolia (Magnolia grandiflora) are among the dominant trees, is composed of about 40 hardwoods and afew conifers just downslope from the fires in the pinewoodsand just upslope from places where the soil is permanently wet (Figure 62). This forest type has been widely touted as the climax forest of the Gulf Coastal Plain (Delcourt and Delcourt 1977), even though old-growth stands are patchily distributed, rather rare, and confined to small areas protected by slopes. a. Solls. The beech-magnolia forests of the Panhandle are capable of growing in a wide range of soils, ranging from the loamy soil at the bases of slopes, on the higher reaches of floodplains, and on the overflow zones of small creeks to xeric, sandy soils. Because fires keep the species of the beechmagnolia forest off of ridge crests and the upper slopes of stream valleys, the actual soils on which the beech-magnolia forests are rooted are not so variable asthey might otherwise be. Usually, soilsof beech-magnolia forests are moderately to welidrained sandy loams, which become clayey within a few feet of the surface. On flat, small stream terraces, organic and clay content is higher than on steep slopes of steephead ravine valleys. In the Marianna Lowlands, the Apalachicola Bluffs and Ravines region, and the Coastal Lowlands where limestone is close to the surface of the ground, beech-magnolia forests seem to be especially well developed.
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b. Ecology. Experimental studies of beechmagnolia forests at Tall Timbers Research Station near Tallahassee, Florida have demonstrated that the regularfiresthat sweepdownslopefromlongleaf forests in clayhill regions of the Coastal Plain keep elements of the beech-magnoliaforest downslope in mesic soil zones where fires are naturally retarded by soil and litter moisture. They also indicate that the mixed pine-oak-hickory forests of Quarterman and Keever (1962) are ~deral successional forests involving elements of the beech-magnolia forest mixed with shonleaf and loblolly pines and other colonizing vegetation. The latter forest type, one of the most common habitat types in the Panhandle today, is human-created, and is discussed in Chapter 5.3.1. When fires are eliminated from the native longleaf pine forests, the hardwoods beginto encroach in an upslope direction (Mutch 1970). Among the hardwoods that are first able to get a roothold in the wiregrass community are sweetgum, laurel oak (Quercus laurifolia), and water oak (0. nigra). In the absence of natural fire, the hardwood forest moves slowly up toward the ridgetops. The drier, sandier soils on ridgetops are less suitable forthese species; nevenheless, most species of the beech-magnolia forest can, in time, grow in even the highest, driest sites. This displacement has happened both naturally and experimentally. There are places in north Florida where an unusual configuration of steep slopes has naturally kept broad, sweeping fires away from isolated ridgetops. Under natural circumstances, longleaf pines would occur on those dry ridgetops but instead, beech-magnoliaforestsoccurthere-in a continuous transect from the moist valleys to the high, dry hilltops. Apparently there are not enough lightning fires on such ridges to kill back the new hardwood growth. Once established, this forest is seif-perpetuating. The beech-magnolia forest, therefore, is the climax forest type on the Coastal Plain uplands, even though those high places are usually the domain of the pines. The tern1 "hammock" broadly refers to any grouping of hardwood trees. Where it occurs on clayey-loamy soils, it is termed a mesic hammock, and the beech-magnolia climax is often found in these environments. Mesic hammocks are particularly rich in numbersof speciesof trees. Most mesic hammcks in the Panhandle occur on the lower slopes of stream valleys throughout the Western Red Hills and Tallahassee Red Hills regions. Hammcks can also be found on sandy, or xeric, soils. Xeric hammocks are often found within sandhill or pine flatwoods communities or on the fringes of lakes and ponds. Clewell (1971) notes that hardwood hammock vegetation often surrounds high pineland depressions especially along the steep slopes of lime sink holes. Overstory trees consist of a mixture of mockernut (Carya tomentosa) and pignut hickory (C. glabra), persimmon (Diospyros virginiana), and southern red oak (Quercus falcata) on drier sites. Hydric hammocks are on the wet end of the soil moisture scale and consequently intergrade imperceptiblywith swampforests. Forthis reasonthey are treated in 6.2.2. TWO of the more prominent characteristics of beech-magnolia associations are their overall diversity as a floristic unit and their compositional variation from site to site. In seeking to determine why different tree species were more prominent in one stand than another, Monk (1 965) examined species composition in termsof soil moisture, calcium, phosphorus, potassium, and magnesium. His conclusions, summarized in Whation (1977, p. 167) are as follows: "(1) Calcium is extremely important; soils high in calcium produce the maximum diversity; (2) Soils low in calcium, potassium, phosphoNS, and moisture support a community dominated by evergreen trees; (3) Some trees, such as water oak [Quercus nigra], swamp chestnut oak [a. pinus], sugarberry [Celtis sp.], spruce pine [Pinus glabra], and blackgum [Nyssa sylvatica], favor wetter environments; (4) Some trees such as sweetgum [Liquidambarstyraciflua] and live oak[Q. virginiana] dowell at both extremesofwet anddry[meaning thatfactors like fire and longevity may be more important when these trees do or do not appear in the forest]; (5) American holly [llex opaca] and wild olive [Osmanthus americanus] preferdry areas, dogwood [Cornus spp.] and hop hornbeam [Ostrya virginica]
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Panhandle Ecologic al Characterlzatlon prefer dry to mesic conditions, and ironwood [Carpinus caroliniana] prefers more hydric soils; (6) Some shrubs and herbs also prefer xeric conditions (sparltleberry [Batodendron arboreum], Elephantopus [elephant's foot], horse-sugar [Symplocos tinctoria], sarsaparilla vine [Smilax pumila]); (7) Of the 49 tree species, Monkfoundonly four; cabbage palm [Sabal palmetto], red bay [Persea borbonia], wild olive, and buckthorn [Bumelia temax], to be of subtropical affinities." c. Flora. Dominant trees include southern magnolia (Magnolia grandlflora), American beech, sweet gum, spruce pine (P. glabra), pignut hickory (Carya glabra), American holly (Ilex opaca), laurel oak (Quercus laurifoiia), white oak, swamp chestnut oak (0. michauxir), hop-hornbeam (Ostrya virginiana), ironwood (Carpinus caroliniana), dogwood (cornus florida), and a host of others. Table 10 lists the tree species found in several unpublished studies of mesic hardwood forests in the eastern Panhandle (Means, unpubl. data). Common shrubs include wild olive (Osmanthus americanus), sparkleberry (Vacc~nium arboreum), witch hazel (Hamamelis virginiana), fringe tree (Chionanthus virginicus), horse sugar (Symplocos tinctoria), strawberry bush (Euonymus americanus), red bay (Perseabohonia), andothers. Woody vines are abundant in the beech-magnolia forest. The giant vines of the muscadine (Vitis rotundifolia), smeared with the orange slime mold (Dicfyostelium sp.) in the spring, the spiked catbrier (Smilax bananox), and the distinctive leaves of poison ivy (Toxicodendran radicans) are always present. Partridge berry (Mitchella repens), trillium (Trillium underwoodi~), violet (Viola floridana), Indian pipe (Monotropa uniflora), and ferns (Polystichum acrostichoides, Thelypteris spp., Asplenium spp. and 0thers) are common herbs in these forests. d. Fauna. Hardwood forests are quite different from the open pine forests of the Panhandle in ways very important to animals. Most of the photosynthesis in hardwood forests goes on high in the lofty canopy where new buds, leaves, flowers, fruits, and nuts abound. The animals that are primary consumers, therefore, are generally arboreal. Lepidopteran larvae in the canopy and a host of sucking and chewing insects are the base of the food web comprised of arboreal insectivores. These mostly are birds, Including vireos, warblers, woodpeckers, and other foliage and bark gleaners. The gray squirrel (Sciurus carolinensis) is the most prominent mammal in the canopy. The forest floor food web in hardwood forests is Vier driven. The leaves, sticks, twigs, flower parts, and seedsof thetrees accumulate on the forest floor and are immediately eaten by a host of terrestrial inverlebrates. Among the more important groups Table 10. Speclesof trees in the beech-magnolla forest association over 100-m transects compared among selected old-growth forests In Panhandle Florlda (from reports on beech-magnolia forests on file wlth the Florlda Natural Areas Inventory, Tallahassee). o = overstory; u =understory. Marianna Caverns Timberlane Woodyard McBrlde's Slough Indian Lake Sweetwater Hill State Park Hammock Hammock Hammock Hilltop Hammock Hammock Acer barbatum o o Acer rubrum u u u Aesculus pavia u Amelianchler arborea u Broussonetia papyrifera u Capinus camliniana u u u u (continued)
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5. Terrestrial Habitats Table 10. Concluded Marianna Caverns Timberlane Woodyard McBride's Slough Indian Lake Sweetwater H~ll State Park Hammock Hammock Hammock Hilltop Hammock Hammock Carya glabra o o o o o Carya pallida o Carya sp. o Celtis laevigata u Cercis canadensis u Cornus florida u u u u u Crataegus sp. u Fagus grandifolia o o o o o o Fraxinus caroliniana o Fraxinus pennsylvanica u Halesia diptera u Hamamelis virginiana u llex opaca u u u u Juglans nigra o o Juniperus nigra u Liquidambar styraciflua o o o o o Liriodendron tulipifera o o Magnolia grandiflora o 0 0 0 0 u Magnolia viginiana u o MONS rubra u u Myrica cerifera u Nyssa sylvatica o o o Osmanthus americana u Ostrya virginiana u u u u u u Oxydendrum arboreum u o Persea borbonia u u o o o Pinus echinata o Pinus glabra o o o o o o Pinus taeda o o Prunus caroliniana u Prunus serotina o o u o o Quercus alba o o o o Quercus hemispJaer~ca o o o o o o Ouercus michauxii u u o o o Querws nigra o o o o Querws hellos u Ouerws ;humardiip o 0 0 Querws stellata o Querws virginiana o Sabal palmetto 0 U Symplocos tinctoria u u 0 Tilia americana 0 0 Ulmus alata u Ulmus americana o o Vaccinium arboreum u Viburnum dentatum u 131
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Panhandle Ecobglcal Charaaerlzatbn are springtails, mites, harvestmen, beetles, hemipterans, millipedes, dipterans, isopods, orthopterans, and earthworms. Spiders, feeding on the detritivores, create another source for the higher consumer levels. The rich litter infaunadrives a sulprisingly complex predator community. Table 8 liststhe terrestrial vertebrates captured in a drift-fence sampling of an old growth beech-magnolia forest (Woodyard Hammock) onTallTimbers Research Station in noahern Leon County. Many other primav and secondary consumers visit the beech-magnolia forest ecosystem, but are not restricted to it. In fact, there seems not to be a single vertebrate that is strictly found in the hardwood habitats. However, a suite of highly visible, large veltebrates are more characteristicof hardwood forests than the pine forestsfurther upslope. These are the gray squirrel, the redshouldered hawk (Buteo lineatus), and barred owl (Strix varia)+cological analogs of the fox squirrel species, red-tailed hawk (Buteo jamaicensis), and great horned owl (Bubo viginianus) inthe open pine forests. 5.2.6 Longleaf FlatWoods Longleaf pine flatwoods are open woodlands that lie between the drier sandhill community upslope and the evergreen shrub dominated wetlands downslope. A drop of only 5 fl in elevation over a distance of 200 m in the Coastal Lowlands will have a longleaf-turkey oak-gophertortoise sandhills xeric community at the high end, a broad, flat, longleaf flatwoods with no understory over 90% of the transect, and an evergreen shrub bog appearing abruptly at the lower end. Standing anywhere along the slope-moisture gradient, however, the casual observer would be unable to visually detect the elevational drop. Flatwoods often are much broader than 200 m. The longleaf pine-wiregrass association was undoubtedly the presettlement dominant forest type of the southeast Coastal Plain It is estimated to have originally covered about 24 million acres from Mobile Bay. Alabama, eastward throughout Florida and then northward through the Coastal Plain in Georgia, South Carolina, and southern North Carolina. Vast flatwood acreages st111 stretch across the Gulf Coastal Lowlands between the Choctawhatchee River and the Ochlockonee River, and between Cody Scarp and the coast. Scrub oaks, common in the sandhills, are absent fmm this wmmunity and the grassy aspect of the ground cover is sometimes obscured by saw palmetto. a. Soils. The soils in pine flatwoods are sandy, ground-water podzols with much organic matter in the upperfew inches associated with the roots of the dominant ground cover, wiregrass. An organic pan is usually present a foot or two into the soil profile. Soils are generally moist at shallow depths with the water table at or near the surface to smut 4 ft deep under drier condiiions. b. Ecology. Working in the Apalachicola National Forest, Clewell (1 971) identified four variants of the pine flatwoods based on dominant species. These include: (1) a longleaf pine phase, (2) a slash pine (P. elliottir) phase, (3) a longleaf-slash pine phase, and (4) a pond pine (P. serotina) phase. The pond pine phase usually contains a compliment of cypress and blackgum and is a truewetland ecosystem. It will be discussed in Chapter 6.2.2. Beforethe influence of people, longleaf pinewas far more common in the overstory of Coastal Plain flatwoods than it is today. Before about 1920, pond and slash pine were generally restricted to wener areas, as were some of the bmsh speclescharacteristic of present-day bay swamps. Reasons for the increase in these species in the flatwoods are still largely unresolved, but are probably related to the disruption of the longleaf pine and wiregrass association by logging practices, silviculture, and most of all, by the interruption of the natural fire cycles. The key to decidingwhetheraGuil Coastal Lowlandssite is a low sandhill or aflatwood site is the watertable. When it is between 0 and 4-5ft beneath the surface, a flatwoods prevails. As noted in Clewell (1 971, p. 35), "Notesof early naturalists indicated that these pinelands contained nearly pure stands of longleaf pine, as many still do today. Only during recent decades of fire suppression have loblolly, pond, and particularly slash pine invaded some of these pinelands. Longleaf pine, which is the only southeastern tree able to survive fire as a seedling and sapling, owes its existence to the highly flammable wiregrass. Wiregrass and the needledropfmmthe longleaf pinecomprise a highly combustible fuel that is ignited by lightning and more
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recently by people. The density ofwiregrass and the dominant ground cover plants in the pine flatwoods. overlap of the blades of adjacent bunches assures According to Clewell (1971), there may be-200 or that afire, once ignited, will spread for miles overthat flat or gently rolling pinelands with nothing to stop its course. In pre-colonial days these fires must have burned at intervals of every 3-4 years in order to have destroyed the seedlings and saplings of all other tree species that had seeded in the pineland since the previous fire." Both species, longleaf pine and wiregrass, have adaptive competitive abilities to maintain their mutual existence. Beside their tolerance to fire, these include an ability to acquire and maintain moisture and nutrients in poor, well-drained soils, the ability to eliminatecompetitive plantsviagrowth patterns, and the ability to perpetuate themselves under adverse conditions. Longleaf pine depends upon the dense carpet of wiregrass for the elimination of competitive tree species that would otherwise replace the pine and prevent its future reproduction, while the pine provides an open canopy (light) and soil conditions (pH and nutrients) conducive to wiregrass cover and associated plants (e.g., yellow fox glove [Aureolaria pedicularia], dwarf huckleberry [Gaylussacia dumosa], and blazing star [Liatris spp.]). Wiregrass does not readily become reestablishedonce uprooted because it does not reproduce sexuallyorasexually except underthemost exacting environmental conditions (Clewell 1974). These include temperature, photoperiod, moisture, and fire. According to the picturedrawn by Clewell (1 974, p. 451, the required conditions may no longer exist, leaving the theory that the wiregrass left today "may have germinated from seeds centuries ago when earlier, post-Pleistocene climates provided the environmental conditions needed for reproduction." Once disrupted by logging or agricultural practices, thls shallow-rooted grass is eliminated from the ground cover, resulting in a permanent successional change to other forest conditions. c. Flora. In addition to the wiregrass and saw palmetto (Serenoa repens), gallberry (Ilex glabra). runner oaks (Quercus minima, 0. pumila), a low blueberry (Vaccinium myrsinites), a ground huckleberry (Gayiussaciadumosa), and bracken fern are mre species of ground cover, with 75 or mre found in any given stand of a few acres. A list of groundcover speciesfound in four Panhandle flatwood sites is given in TaMe 11. d. Fauna. The flatwoods of the Gulf Coastal Lowlands, especially in the Apalachicola National Forest, support a robust population of native earthworms of the genus Diplocardia. One Species, particularly, D. mississippiensis, is the focus of a large fishing bait industry. Many local residents Of Calhoun, Liberty, and Wakullacountiesmake agood living by gathering this species by means of the technique called "grunting." A wooden stake is driven into the ground andvibrated by drawlng an ax handle, shovel handle, or similar device across it. The vibrations in theground agitate the earthworms, driving them to the surlace where they are collected. Bait collectors like to "grunt" recently burned flatwoods, wheredensitiesof D. mississippiensisareon theorderof thousands per acre. This species, alone, must do a considerable job in recycling organic nutrients back into the soil. The groundcover of flatwoods is usually quite luxuriant because water is readily available during rains which do not percolate far into the soil to local water tables. Furthermore, under the natural conditions of regularfires, nutrients tied up in dead and slowly decomposing organic litter are quickly made available to the plants of flatwoods by the rapid oxidation and nutrient-cycling effect of fire. ~ecause the primary productivity of the groundcover vegetation is so high, flatwoods support a rich invertebrate fauna of herbivores. These, in turn, drive a surprisingly richvertebrate insectivore f auna, comprising salamanders (Ambystoma talpoideum, A. tigrinurn, A. cingulatum, Notophthalmus viridescens, N. pentriatus, Eurycea quadridigitata), frogs (Gastrophryne carolinensis. Bufo tenestris, 6. quercicus, Hyla squirelia, H. fernoralis. H. gratiosa. Pseudacris ornata, P. nigrita, Limnaoedus ocularis, Rana sphenocephala. Scaphiopus holbrooki~), and lizards (Eurneces Inexpectatus, Scincella lateralis, Cnemidophorus sexlineatus, Ophisaurus ventralis) Snakes that feed upon the herbivores are abundant also (Coiuber constrictor, Lampropenis getulus, L.
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Panhandle Ecological Characterization Table 11. Comparison of floral dlverslty among four flatwoods Sites In Panhandle Florida. Slte l=Liberty couniy flatwoods; site 2=~ate'skell swamp; slte3=grass-sedgesavannah, Llbeny County; site 4=Buckhorn Hunt Camp (from research summarles 6.7.9.8 5, respectively, In Clewell 1981). Site Site Site Site Species 1 2 3 4 Agalinis aphylla Agalinis filicaulis Agalinis linifolia Agalinus pupurea . Ageratina aromatics eris aurea Aletris lutea . Aletris obovata Angelica dentata Andropogon virginicus Andropogon sp. Anthaenantia rufa -Aristida affinis Aristida stricta -ssum ovaturn Aronia arbutifolia Asclepias cinerea Asclepias wnvivens Asclepias lanceolata Asclepias longifolia Asclepias michauxii Ascyrurn (=Hypericum) hypericoides Asimlna bngifolia Aster adnatus Aster chapman;; . Aster concolor Aster durnosus Aster eryngiifolius Aster linariifolius Aster retiwlatus Aster tortifolius Aureolaria pedicularia Balduina uniflora Baptisia lanceolata Baptisia simplicifolia Bartonia paniculata Berlandiera purnila Bigelowia nudataCallicarpa americana Calopogon pallidus . Calopogon tuberosus (=C. pulchellus) Slte Site Site Site Species 1234 Carphephorus pseudoliatris . Cassia fasciculata Cassia nictitans Chamaecyparis henryae Chaptalia tomentosa Chondrophora nudata Chrysopsis mariana Cirsium honidulum Cirsium lecontei Cleistes divaricata Clethra alnifolia . Cliftonia monophylla Cnidoscolus stimulosus Coreopsis gladiata Coreopsis leavenwoflhii Coreopsis nudata Cmtalaria purshii Ctenium aromaticum Cuscuta compacta Cyrilla racemiflora parvifolia Cyrilla racemiflow Desmodium ciliare Desmodium lineatum Desmodium paniculatum Dichanthelium acuminatum . Dichromena wlorata Dichromena latifolia . Diospyros virginiana Dmsera capillaris . Drosera filiformis Dyschoriste oblongifolia Elephantopus elatus Erianthus giganteus Erigeron vernus Erigemn tomentosum Erlocaulon compressum Eriocaulon decangulare . Eryngium yuccifolium . Eupatorium album Eupatorium compositifolium Eupatorium leucolepis Eupatoriumrecurvans . Eupatorium rotundifolium (continued) 134
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5. Terrestrial Habitats Table 11. Site Site Site Site Species 1 2 3 4 Eupatorium semiserratum Euphorbia inundata Euthamia minor . Fraxinus camliniana Fuirena squarrosa Galactia erecta Gaylussacia dumosa Gaylussacia frondosa Gaylussacia mosieri Gelsemium rankinii Gelsemium sempervirens Gnaphalium purpureum falcatum Heleanthemum carolinum Helenium pinnatifidum Helianthus floridanus Helianthus heterophyllus Helianthus radula Heterotheca (=Pityopsis) aspera Heterotheca (=Chrysopsis) gossypina Hetemtheca (=Pityopsis) graminifolia Hetemtheca (=Pityopsis) oligantha . Hibiscus aculeatus Hieracium gmnovii Houstonia (=Hedyotis) procumbens Hyperiwm brachyphyllum Hyperiwm fasciculatum Hyperiwm microsepalum Hyperiwm myrtifolium Hyperiwm tetrapetalum Hperiwm stans Hypoxs hirsuta . Hyptis alata llex wriacea . llex glabra llex myrtifolia . Iris tridentata Justicia crassifolia Kalmia hirsuta Lachnanthes caroliana Continued Site Site Site Site Species 1234 Lachnocaulon anceps Lespedeza capitata Lespedeza repens Liatris chapmanii Liatris gracilis Liatris spicata . Liatris tenuifolia Licania michauxii Lilium catesbaei . Lobelia brevifolia Lobelia floridana . Lobelia paludosa . Lophiola americana . Ludwigia linearis Ludwigia pilosa Lycopodium alopecuroides . Lycopodium carolinianum Lycopodium prostratum Lygodesmia aphylla Lyonia ferruginea Lyonia fruticosa Lyonia lucida . Magnolia virginiana . Muhlenbergia capillaris Myrica cerifera . . Myrica heterophylla Myrica inodora . Nolina atopocarpa Nyssa sylvatica biflora . Onosmodium virginianum Osmanthus americanus Osmunda cinnamomea . Oxypolis filiformis . Panicum anceps Panicum rigidulum Parnassia camliniana Paspalum plicatulum Paspalum sp. Persea palustris . Petalostemon albidum Phoebanthus tenuifolia Physostegia leptophylla Pieris phillyreifolia Pinguicula sp. Pinus eliiottii . . (continued) 135
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Panhandle Ecological Characterlation Table 11. Site Site Site Sne Species 1 2 3 4 Pinus palustris Plantanthera ciliaris Plantanthera nivea . Pleea tenuifolia . Pluchea camphorata Pluchea foetida Pluchea odorata Pluchea msea Pogonia ophroglossoides Polygala baldwinii Polygala crenata Polygala cmciata . . Polygala cymosa Polygala grandiflora Polygala harperi Polygala incarnata Polygala lutea . Polygala nana Polygala ramsa Polygala setacea Proserpinaca pectinata Pteridium aquilinum Pterocaulon pycnostachyum (=P. virfatum) Quercus falcata Quercus incana Quercus laevis Quercus minima Ouercus nigra Quercus pumila Rhexia alifanus Rhexia lutea Rhexra petiolata Rhexia virginica Rhododendron sermlatum Rhynchospora chapmanii Rhynchospora mmiculata Rhynchospora globularis Rhynchospora microcephala Rhynchospora mllissima Rhynchospora plumosa Rhynchospora sp. Rubus argutus Rubus cuneifolius Rudbeckia graminitolia (continued) Continued Site Site Site Site Species 1234 Rudbeckia mohrii Ruellia pedunculata Sabatia bartramii Sabatia brevifolia Sabatia difformis Sabatia quadrangula Sabatia stellaris Sagittaria graminea Salvia azurea Sarracenia flava . Sarracenia psitlacina . Schrankia microphylla Scleria baldwinii Scleria hirfella Scleria nitida Scleria retiwlaris Scleria triglomerata Scutellaria integrifolia Serenoa repens Seymeria cassioides . Sisyrinchium arenicola Smilax auriculata Smilax glauca . Smilax laurifolia . Smilax pumila Solidago odora Solidago stricta Spiranthes praecox Stylisma patens Stillingia sylvatica Stylosanthes bitlora Styrax americana Syngonanthus flavidulus Taxodium distichum nutans (=T. ascendens) . Tephrosia hispidula Tephrosia virginiana Tofieldia racemosa . Tragia urens Trichostema dichotomum Trilisa (=Carphephoms) odoratissimus . Trilisa (=Carphephorus) paniculatus Utricularia cornuta 136
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5. Terrestrial Habitats Table 11. Concluded Site Site Site Site Species 1234 Utricularia juncea . Vacciniurn darrowi Vaccinium fuscatum Vacciniurn myrsinites Verbesina chaprnanii Viola septemloba Viola sp. Vilis mlundifolia . vitis sp. Woodwardia virginica Xyris arnbigua Xyris baldwiniana . Xyris caroliniana . Xyris ellionii The avifauna of flatwoods is of four feeding guilds: an arboreal, needle and barkgleaning suiteof species; aflycatchinggroupthat salliesout from their perches to catch insects in the air: a seed-eating terrestrial assemblage; and a group of aerial predators. Preeminent among the birds of the first guild is the federally endangered red-cockaded woodpecker (Picoides borealis). The last strong bastion of this species is the Coastal Lowlands of Panhandle Florida. Eglin Air Force Base and the Apalachicola National Forest probably harbor more than 50% of the remaining individuals of this species. The aerial predators are nocturnal and diurnal, including thegreat horned owl (Bubo virginianus), red-tailed hawk (Buteo jamaicensis), and chuck-will's-widow (Caprimulgus carolinensis). The Bachman's Sparrow(A1m~hilaaesXyr~s str~cta . . . t!val~s) Isafully terreslr~al birdthat requireithe open. Zngadcnus dcnsus shrubless prair~e qroundcover typical of flatwoods. Zigadenus giaberrirnus . Total species 5.2.7 Beach, Dune, and Scrub 134 87 127 71 The beach and dune coastal strand vegetative associations are restricted to the high energy shorelines along the seaward boundary of the spits and barrier islands of Panhandle Florida. The barrier triangulum, L. calligaster, Masticophis flagellum, islands are Santa Rosa. Shell, St. George, St. VinDrymarchon corais, sistrurus mi~ianus, Naphe gutcent, and Dog Island; the larger spits are Moreno tata, E. obsoleta). Point, Crooked Island, St. Joseph Spit, and Alligator Peninsula. One small stretch of mainland exposed Mammals of the flatwoods are most ofthe same to the Open gulf, from Alligator Point to Dog Island, species found in sandhills. They include the mamhas a small amount of strand vegetation. Coastal malian insectivores: shrews (Blarina brevicauda, marshes and salttlatsfound along low-energy coastCryptodus parva, ~orex ~ong~mstr~s) and the mole lines are not considered components of the strand (Scalopus aquaticus). Mammalian herbivores are community, norare the uplandcommunities, such as abundant: cottontail and marsh rabbit (Sy/vilagus the Pine flatwoods found inland of the dune system flor~danus, S. palustns), conon rat andcotton mouse and along shorelines being eroded by the sea. (Sigmodon hispidus, Peromyscusgossypinus), harvest mouse (Reithrodontomys humulis), pine vole a. Soils. Soils of the coastal strand, as the (Microtus pinetorum), white-tailed deer (Odocoileus beach, dune, and coastal scrub are often called, are virginianus), and others. Most of the mammalian sandy,gradingfromunsorted, mixedgrainsizesand carnivores (skunk, opossum, raccoon, bobcat, gray shellsthrown up as berms by stormstofinely graded fox) not strictly associated with water are found In and sorted grain sizes on aeolian dunes. These flatwoods. Since watercourses meander through latter dunes occur perched on the interdune flats or the flatwoods, the aquatic mammals (otter, mink, are developed on top of the berms thrown up by beaver) occasionally enter the piney woods. The storms. threatened black bear is found in small numbers in deep swamps like Bradwell Bay Wilderness Area b. Ecology. The scrub community, which is located in the flatwoods of the Apalachicola National unique to the southeasterncoastal Plain andespecForest. ially to Florida, has two variants, one dominated by 137
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Panhandle Ecological Characterlzatlon sand pine (P. clausa), and one dominated by slash pine (Pinus elliotti~). On Panhandle barrier islands, treeless scrub occurs just behind the foredunes in the lee of winds heavily laden with sail spray off the Gulf of Mexico. Going inland, the treeless scrub changes to scrub with a slash pine canopy. Further back from the first or second beach-dune ridge, one encounters sand pine scrub. This transect is obvious on St. Joseph Spit, St. George Island, and St. Vincent Island. As in peninsular Florida, pine scrub of the Panhandle is also found on relict sand dunes and beach ridges created when sea level was higher than at present. Soilson such relict dunes are well-washed, well-drainedsterilewhite-to-yellowishsands. Unlike peninsular Florida sc~bcommunities, however, the Panhandle scrub community tends to be closer to the coast, positioned between the coast and the pine flatwoods. The pine scrub habitats of Panhandle Florida are isolated from those in the north central peninsula by the low-energy coastline of the Florida Big Bend region, where few dunes have been formed. c. Flora. Though variable from site to site, dune and beach vegetation can have three distinguishable zones: (1) the shifting beach sands; (2) the produne vegetation; and (3) the scmb zone. The shifting beach sand zone is, by definition, devoid of living, rooted vegetation. The primary energy sources for the often numerous consumers that frequent this zone are imported by wind and wave action or brought down from more inland areas. Seagrasses washed onto the shoreline by storm tides and waves, drifting plant debris, shells, and carcasses of fish and other marine lie, collectively called seawrack, serve as food for the primary consumers that include many insects and their larvae, amphipods, ghost crabs (Ocypode sp.), and otherburrowing inverlebrate species. These, inturn, provide food forgulls, terns, and probing shorebirds. Inland from the shifting beach sand zone, the produne zone is the first large dune. Produne vegetation is characterized by pioneer plants that are able to establish themselves in the shining, arid sands and to tolerate salt spray and intense heat. Examples include sea oats (Uniolapaniculata), railroad vine (Ipomoea pes-caprae), beach morning glory (I. stolonifera), evening primrose (Oenothera humifusa), sand spur (Cenchrus tribuloides). grasses ( Paspalum vaginatum, Schizachyrium maritimum, Panicum amarum), sand cocograss (Cypeus leconte~), and sea purslane (Sesuvium porlulacastrum) (Kurz 1942; Clewell 1971). Limited quantitative dataon the density of these dune plants on St. George Island are provided by Carlton (1977). The produne affords limited protection to the interior dune system from wind and salt spray and is crucial for the establishment of subsequent plant communities. On the backsides of these dunes Spanish bayonet (Yucca aloifolia), myrtle oak (Quercus myrtifolia), green brier (Smilax auriculata), saw palmetto (Serenoa repens), and other plants characteristic of the interior dunes may grow. Farther inland from the foredunes is the "scrub" zone, characterized by stunted, wind and salt spraypruned scrubby oaks and other evergreen, smallleaved shrubs. This area is referred to as the "scrub" zone by Kua (1942), because of its similarity to scrub oak growing on relict sand dunes of interior Florida. The scrubby, gnarled, thick-leaved evergreen oaks that are characteristic of the scrub community almost always include sand-live oak (0. virginiana gerninata), Chapmans oak (0. chapmanil). fettetbush (Lyonialucida), and very rarely in the Panhandle, myrtle oak (Quercus myrlifolia). Other common shrubs include different types of rosemary (Ceratiola erimides, Conradina canescens) and gopher apple (Licania michauxi~). Ground cover is usually sparse, leaving large patches of bare white sand interspersed with reindeer moss (Cladonia rangifera) and other lichens. The scrub community istypically two layered, with slashor sand pine in the canopy and the scruboaks and shrubs in the understory. Scrub communities are quite variable. The coastal scrub forest is dominated by a mixture of sand and slash pine in most locations (Carlton 1977). However. according to Clewell (1971), sand pine was represented by a single tree in his suwey of St. George Island. Comparable dunes near Carrabelle and on St. Joseph Spit have dense forests of sand pine (Pinus clausa). Sand pine seems to be lesstolerantof saltspraythanslashpine. Therefore,
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5. Terrestrial Habltats it is common to find sand pine on the interior dunes ing water remains nearly all year pond habitat may or bayside beach ridges and dunes on the form, supporting freshwater marsh plants such as Panhandle's barrier islands. Across the lagoon, sawgrass, water lilies (Nymphaea odorata), and where sand pine is somewhat better sheltered from umbrella grass (Fuirena scirpoidea). heavy winds andsak spray, it occurs indense stands on relitdunes and beach ridges alongthe continenThe vegetation of the coastal community is tal margin. Eglin Air Force Base is notedforavariety subjected to harsh conditions. High winds, shifting of sand pine having open, rather than serotinous cones, such as the sand pine has in central Florida. Sand pine forests include monospecific stands of uniform age, indicating regeneration about the same time. This coincides with theories about natural replacement of sand pine by fires in central Florida (Laessle 1958). It is common to find sand pine growing with other pines, such as longleaf pine on Eglin Air Force Base. Apparently sand pine will encroach under the canopy of longleaf pine in the absence of fire. In stands of old sand pine, wind seems to be able to blow over large individuals, opening the sand pine forest up for invasion by hardwoods, other pines, and shrubs. The successional relationshipsof Panhandle sand pine have yet to be fully studied. Open areas of the scrub zone are sometimes occupied by lichens, St. Johns wort (Hypericum reductum), nettles (Cnidoscolus stimulosus), stunted sea oats, and jointweed (Polygonellapolygama). Swales between dunes may occasionally retain water after heavy rains. These shallow interdunal depressions may be distinguished from sloughs in that they drain surface runoff vertically into the soil, whereas sloughs hold surface runoff or carry it into the bay (Clewell 1971). On St. George Island, sloughs are generally flanked by pine flatwoods and are delineated by a dense zone of medium-sized oaks. These rnesic to xeric-like hammock communities are composed primarily of laurel oak (Quercus laurifolia) and live oak with some sand-live oak (Q. virginiana geminata), as well (Clewell 1971). A variety of woody plants form an understory in this more protected habitat, including gallberry (Ilexglabra), wax myrtle (Myrica cerifera), greenbrier, bamboo vine (Smilax laurifolia), poison oak (Toxicodendron quercifolia), muscadine (Vitis rotundifolia), wild olive (Osmanthus americanus) yauijijfi (Ilex vomitoria), buttonwood (Cephalanthusoccidentalis), royal fern (Osmunda regalis), and sawgrass (Cladium jamaicense). Where standsands, intense heat, and salt spray are chronic stress factors which define not only species composition, but growth formas well. Many plantsfound in the coastal region appear to be gnarled and stunted, perhaps as adaptationsto orconsequences of environmental stress. Despite the fact that many plants may appear stunted or small, they are frequently quite old. Clewell (1971) reports a myrtle oak 2 m in height to be at least 11 years old; a 2.3 m sand live-oak to be 25 years old; a 1.3 rn rosemary bush to be 15 yearsold; anda25.4crndiarneterslash pine to be75 yearsold. Though they appear stressed, many of the scrub species survive quite well under such conditions. Their success is essential to the stabilization of the dune system, which is constantly subjected to the eroding force of onshore winds and storms. Althoughfiretendsto be infrequent inthecoastai community, it does occur (Clewell 1971) and is important in maintaining other more typically inland community typeson barfier island systems (i.e ,pine flatwoods, pine scrub). Because of the openness of the scrub zone and the lack of fuel in the ground cover, fewerfires occur and they rarely spread very far in the dune system. The slash pine scrub community described by Clewell (1971) in the Apalachicola National Forest possesses more than just scrub oak understory. Sand-live oak (Quercus virginiana geminafa), sweet bay magnolia (Magnolia virginiana), southern rnagnolia (Magnolia grandiflora), and stagger bush (Lyonia ferruginea) were common stunted trees, 1030 fi tall. Others included black titi (Cliftonia monophylla), wild olive (Osmanthus americanus), water oak (Quercus nigra), and others. The overstory, which has been cut, was solely slash pine (Pinuselliotti~), upto 120 yearsinage before logging. The scrub layer in this community contains fetterbush (Lyonia lucida), stagger bush, gallberry (Ilex glabra), dwarl huckleberry (Gaylussacia spp.),
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Panhandle Ewloglcal Characterlzatlon dangleberry (Vaccinium erythrocarpum), and sandlive oak (Quercus virginiana geminata). Saw palmetto (Serenoa repens) grows sparsely. Only 51 species are recorded from this upland site. On St. George Island, a slash pine dominated scrubcommunity lies behind the dune system, often intergrading into sand pine scrub and pine flatwoods (Clewell 1971). lnthis particular location, myrtle and sand-live oak form large patches and saw palmetto covers up to 15% of the ground. Chapmansoak and rosemary were also reported. Two trends in this community'sdistribution have been noted: (1) the invasion of sand pine into sandhill sites as fire is eliminated (Gatewood and Hartman 1977); and (2) the establishment of a slash pine overstory at sites formerly dominated by sand pine as the sand pines reachold age and beginto fall down and thin out (Clewell 1971). Fire suppression in sandhill communities may slow the recycling rate of organic nutrients in the forest litter and eliminate wiregrass, lowering overall soil fertility and thus favoring the invasion by sand pine. The deliberate planting of slash pine may promote its invasion into adjacent scrub communities by increasing the relative numbers of seeds reaching available sites. Fire suppression may also play a role in promoting slash pine. In south Florida sand pine scrub is recycled by catastrophic fire (Laessle 1958, Bozeman 1971). Much less is known about the role of fire in north Florida scrub communities, and extrapolation from the ecology of central Florida scrub may be invalid. d. Fauna. The dunes are so arid and hot that few amphibians can tolerate the severely stressful conditions. Southern toads (Bufo terrestris) occasionally take refuge in burrows and forage at night at the base of dunes, especially in the interdune flats. Toads can be abundant in coastal strand environments ascan the southern leopard frog (Ranasphenocephala) because both breed in temporary ponds of the interdune flats. Coastal strand environments are well endowed with reptiles. Reptiles are the vertebrates best adapted for dry terrestrial environments, and the kinds of foods eaten by most reptiles (insects, small vertebrates) are themselves abundant in the highly productive coastal habitats. The garter snake (Thamnophis sirtalis), black racer (Coluberconstrictor), coachwhip (Masticophis flagellum), cottonmouth (Agkistrodon piscivorus), and pygmy rattlesnake (Sistrurus miliarius) are also exceedingly abundant along strands. Mammals of the coastal strand include the eastem mole (Scalopus aquaticus), shrews, beach mice (Pemmyscuspolionotus sbspp.), rice rat (Olyzomys palustris), cotton rat (Sigmdon hispidus), cottontail (Sylvilagus floridanus), and marsh rabbit (S. palustris). Panhandle scrubcommunities are depauperate in animals when compared to the central Florida interior scrubs. Apparently the Panhandle scrubs are only as old as the barrier islands and the coastline where it is confined geographically. Present coastal features are only about 6,000 years old, but interior scrubs in central Florida are relicts stranded from higher stands of the sea, possibly as long ago as late Pliocene, and may be upto2 million yearsold. Coastal scrub communities from Santa Rosa Island to St. Joe Spit have populations of lightcolored beach mice that burrow in the sand. These, cotton rats, and rice rats probably are eaten by the coachwhip and black racer, common snakes in the scrub that actively hunt their prey. They also eatthe six-lined racerunner (Cnemidophorus sexlineatus), one of the commonest scrub vertebrates. Southern toads are the most common frog, but the southern leopard frog is also abundant. Many of the animals encountered in scrubs are visitors from adjacent wetlands, forests, or grassland vegetation. Two federally listed endangered subspecies, the Choctawhatchee beach mouse (Peromysws polionotus allophnys) and Perdido Key beach mouse (P. polionotus trissyllepsis) are found on some of these barrier islands. 5.2.8 Caves Caves filled with air rather than water are generally rare in Florida but are more prevalent in the Panhandle than in the peninsula. This typeof habitat is found in regions with limestone formations. Two distinct limestone (karst) regions exist in north Florida west of the Suwannee River, each biologically and geologically distinct from the other: the Woodville Karst Plain in the Florida Big Bend region and the Marianna Lowlands in the Panhandle. Air-filled caves are virtually nonexistent in the subterranean
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5. Tsrrestrlsl Habltats limestone passageways of the Woodville Karst Plain, but they are abundant in the Marianna Lowlands. The reason seems to be that the water table in the Marianna Lowlands is lower than the general elevation of the upper limestone passageways, allowing air, ratherthan water, to fill thecaves. The airfilled passageways are connected by vertical shafts to water-filled passageways in horizontal cave systems at lower levels. The biological resources of water-filled caves are described in the chapter on freshwater wetlands (Chapter 6.5.1). The Marianna Lowlands physiographic regionof Panhandle Florida is the southwestern end of a large karst plain known in Georgia as the Dougherty Plain. This limestone region extends northeast from Marianna, Florida, to about 25 mi beyond Albany, Georgia. The Tertiary limestones which lie close to the ground surface, mantled with a thin veneer of sand, have been subject to erosion by dissolution for millions of years, and both vertical and horizontal solution channels are extensive in them. Vertical shafts dissolve as surface waters percolate downward through joints, cracks, fissures, and faults; horizontal caves are formed as ground water flows downhill underground along bedding planes between limestone terranes (sediment layers). Over millions of years, horizontal tunnels can widen to become 30-50 ft in diameter, or even larger in places. When in timesea levelsdrop, asthey periodically do in Florida in response to the waxing and waning of continental glaciation, ground water levels also fall. When ground water drops, it abandons upper horizontal cave systems through vertical interconnecting shafts and occupies horizontal systems at lower levels in the limestones. Once the water in the passageways is replaced with air, they are available for colonization and use by terrestrial animals and plants. Because light is always a limiting factor in food webs (except some deep sea ones), it is no surprise that light, or the lack of it, plays a role in cave ecosystems. Light intensity declines as the square of distance, so that the intensity of light available for photosynthesis falls off very rapidly back from the cave mouth. Veryfewcaves exist intowhich sunlight falls directly. The area near the mouth of a cave where any amount of light falls is called the "twilight" zone. This is not an abstract category; animals and plants that use and/or need light are speclically found in this zone in caves, and their distributions in the twilight zone are quite demonstrable on inspection. The dark portions of caves are, of course, just aswell-defined by the absence of any light at all, and the simplified food webs in the dark (troglobiic) zones of caves are driven entirely by detritus. Most of the cavesof biological Importance in the Marianna Lowlands are privately owned, but two systems now belong to the State of Florida. The caves in the Marianna Caverns State Park include a few thousands of feet of passageways. None of these caves is particularly important biologically, andthe main commercialcavern isdisturbed daily by the tourist traffic. Some of the park's smaller caves, such as Indian Cave, are being managed in hope of the return of the endangeredgrey bat (Myotisgrisescens). which is known to have once used them. One of the most important caves in the region, biologically, is known as Judge's Cave. This cave now is owned by the Florida Game and Fresh Water Fish Commission. It is the major maternity cave for the grey bat, whose pregnant females seem to require a most over water in caves (Tuttle 1974, Humphrey and Tuttle 1978). Other privately owned caves that are important biological resources are known by the following names. Bump Nose Cave, Honey Comb Hill Cave. Stoney Cave, Fears Cave. Sam Smith's Cave #l (also known as Gerard's Cave), Sam Smith's Cave #2, and Baxter Cave, all in Jackson County. Many more occur in Jackson County Some are clustered along the Chipola River valley between Marianna Caverns State Park and U. S. Highway 90, and others are found to the west in the direction of the town of Cottondale. Another cluster of caves lies along Waddell's Mill Creek and 11s tributar~es west ot the Ch:pola Rlver The Flor~da State Cave Club, a grono (branch) of the National Speleological Society and operating out of Florida State University in Tallahassee, maintains records on the caves of the Panhandle and has maps of many. a. Flora. It may come as some surprise that the twilight zones of caves in the Panhandle have a distinctive flora. Caveplantsare mostly microscopic
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Panhandle Ecologlcal Characterlzatlon species, and in the Panhandle are limited to algae, fungi, and bacterla. While cave flora have not yet been thoroughly investigated in Florida caves, at least two species of algae have already been described as endemicto Panhandle caves (Friedmann and Ocampa 1974). Liverworts and fungi are common about the mouths of caves, and fungi occur far back in the dark zones, especially on bat guano. b. Fauna. There are many animals that use caves casually because they provide shelter and buffered air temperatures. For many animals caves may seem to be no more than just larger cracks and burrowsthatthey normally inhabit. The Floridawood rat (Neotoma floridana) commonly builds its stick nests just inside caves in the twilight zone, usually under large rocks or in fissures in the walls. The slimy salamander (Plethodon glutinosus), two-lined salamander (Eurycea bislineata), and long-tailed salamander (Eurycea Iongicauda) are three common casual visitors to the Marianna caves. The camel cricket (Ceuthophilus spp.) is found abundantly in Panhandle caves, in the twilight zone and throughout the dark zone. Cambala annulata is a cave millipede found in Marianna caves, along with the cave spider, Islandia sp. 5.3 Human-created Habitats 5.3.1 Fallow Lands, Succession, and Mixed Hardwood Forests of the Marianna Lowlands attracted the first settlers and consequently, have been disturbed by the plow the longest. In the Coastal Lowlands cultivated and, later, fallow land have always been less abundant becausethe sandy soils are poorfor agricultural use. Site preparation for silviculture has had similar impacts in the Coastal Lowlands (see Section 5.3.3). b. Ecology. At one time or another, most of the naturally richer soils of the Coastal Plain have been farmed. In the pre-Civ~l War South agriculture was the primary industry of the Coastal Plain, and it still is important today. Until the 1940's and 1950's, when commercial fertilizers began to be used on a grand scale, farmers had to rotate their crops from site to site and let fields lie fallow for a few years to restore their fertility naturally. But in the Coastal Plain no land lies unclaimed for long. Many plants spread seeds using the wind, water, animals, or birds for distribution. Soon a rich flora develops on the old field sites. Several species of hardwoods from beech-magnolia torest may take mot. The first of these are usually sweet gum, laurel oak, andwateroak. Apinefromthatsameforest, the loblolly pine, may recruit and establish ltself provlded that it can escape death by fire in the first decade of its life. The shortleaf pine also invadestheoldfields. It followed settlers coastward from its natural hab~tat in the Piedmont. Today, most of the pine forests in ,he coastal Today, many ofthe pine forest softhe southeast Plain are very different from the native longleaf grow on former longleaf sites that were cleared, communities they have replaced, the pines farmed, and abandoned. Where these forests are themselves are different Shnrtloaf (Pinrrs orhinaburned each Year, the hardwoods are suppressed, . . . . . . -. . . . . ta), IO~IOII~ (P. taeda), and slash pine (P. e~~iotti,) and an open, parklike panorama of large old field have replaced longleaf pine. Second, these areas pines can be produced. When these stands are 40 areas much hardwoodcommunities asthevareoine to 80 years old, they begin to resemble the native forests. These replacement forests are oldiield kccessional communities, and they result from the most serious of human impacts to longleaf forests: soil disturbance. a. Solls. The soilsof fallow lands are usually the richest and the highest in elevation-those that are naturally best suited for agriculture. In the Panhandle, the best agriculural soils are the loamy soils of the Northern Highlands. The sediments of the Miccosukee and Citmnelle Formation in the Northern Highlands, and the nutrient rich calcareous soils longleaf vistas, but a closer look reveals that the replacement forests contain a very different mix of plants than the orlginal longleaf forests. For one thing, hardwoods that grow up with the replacement pines are rarely eliminated, because their persistent roots keep putting up new shoots. If fire is kept out long enough, the large hardwood rootscan thrust up stems very rapidly and grow big enough to survive the next fire. With infrequent fires, old fields inevitably become hardwood stands. The hardwoods make it
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5. Terrestrial Habltats even more difficult for fire to sweep through, and young shortleaf and loblolly pines cannot survive under the dense shade of the hardwoods. The old field site eventually changes into a hardwood community as the original shortleaf and loblolly individuals age and die. The strong dependency of many native groundcover plants (and longleaf pines as well) on summer fires for sexual reproduction is probably a major reason that fallow land does not recruit the same mix of species that make up a virgin forest, even if adjacent to one. Another reason, however, is that among the species of any community, some are better adapted for colonizing bare soil than others. Bare soil of the sizes left by humans following agriculture orother artificial soil disturbance are unusual site conditions that probably never existed in presettlement times. Large patches of bare soil are quickly colonized, not by a random sample of the native flora, but by a highly biased subset of the native flora involving mostly the good colonizers (sometimes called 'kreeds"). These species naturally occur at very low densities under normal conditions. Broomsedge (Andropogon viryinicus) and dog fennels (Eupatorium spp.), whose density on old fields can be almost impenetrable, are good examples of native species that in longleaf ecosystems are relatively rare because they are found on a few bare patches of soil that exist only for short periods. Such bare patches are created by tree tip-up mounds when trees fall over, or consist of soil pushed up by burrowing animals such as the gopher tortoise or pocket gopher. Because these patches are small and rare, the plants that are adapted forfinding and utilizing them usually have high fecundity and high dispersabiliy. Lots of seeds, produced every year and carried by the wind, ensure that these species will find the rare and fleeting bare soil sites in native longleaf communities. Fallow soil, however, is selectively colonized by these species, creating vast instead of normally tiny populations. Weeds Introduced from Asia, Europe, Africa, South and Central America, and elsewhere in North America by people have also invaded the Coastal Plain. These join with native weeds and are called ~deral "communities." c. Flora. The mixed pine-oak-hickoryforests of Quarterman and Keever (1962) are not, as they believed, the natural climax community. These communities are late successional stages of fallow lands. Numerous grasses and forbs dominate the early stages of tield abandonment. Woody perennials succeed the succulent annuals, and include Eupatoriumspp., Rubusspp., sassafras (Sassafras albidum), wlnged sumac (Rhus copallina), beautyberry (Callicarpa americana), and young stems of several hardwood species, including sweet gum (Liquidambarsfyraciflua), water oak (0. nigra), laureloak (Q.laurifolia), black cherry (Prunusserofina), pignut hickory (Carya glabra), mockernut hickory (Carya tomenfosa), southern red oak (Quercus falcata), occasional live oak (Quercus virginiana), persimmon (Diospyros virginiana), and others. When these tree species begin to rise above the perennials, they are in a race skyward with the old field pines (shortleaf and loblolly). At first the pineswinthe race, establishing a canopy above the slower growing hardwoods. If regular fires sweep these forests after about 7 or 8 years, the hardwoods will be pruned back to rootstocks after every burn, allowing the pines to dominate the site. If no fires sweep the site, or they come at great intervals, the hardwoods will reach the canopy and share ~t awhile w~th the pines. The hardwoods, however, can replace themselves with new recruits when an opening occurs in the closed canopy; the pines, belng intolerant of shade, can not. Eventually, as the old-field pines die, the mixed pine-oak-hickory forest becomes an exclusively hardwoodcommunity. Most of the arable land of the Panhandle, if not presently under cultivation, is in some stage of successional recovery from it or has been totally converted into living space for people d. Fauna. Many of the animals that inhabit the longleaf pine clayhills uplands are found in the short leaf loblolly pine woodlands, if these are burned regularly (annually). But dense stands of young hardwoods and pines were not present in the Panhandle in pre-Coiumbian times, and few animals are preadapted to do well in thls now common community type. A recent study of the breeding birds of an 80-year old, annually burned old-field community showedtwothings: (1) Thefaunaof theforest. which was similar physiognomically, to a longleaf pine forest, was not too different from that habitat; and (2) when the annual burning ceased, there was a measurable decline in the presence and abundance of
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Panhandle Ecological Characterlzatlon birds that favor open, prairie-like pinelands. (Engstrom et al. 1984). In a drift-fence study comparison of an original growth longleaf pine forest with an 80year old, annually burned shorlleaf loblolly pine forest, Means and Campbell (1982) showed little difference between the terrestrial herpetofauna (Table 8). It is not known, however, what happens to the suite of species if annual fires are stopped. 5.3.2 Silvicultural Communltles Probably as much of the terrestrial environment of the Panhandle is devoted to silviculture as comprises all other terrestrial habitat types combined. The largest timber growers are private pulp and lumber w~porations who have holdings in every county. Next in total area are the State and Federal lands devoted to tree farming, including the Blackwater River State Forest, Apalachicola National Forest. Eglin Air Force Base, and St. Marks National Wildlife Refuge. Tree farming by small private land owners is also extensive and may approach, insheer acreage, the sum of the large corporate holdings. a. Solls. Soils range from ultisols to spodisols to entisols. Pine tree silviculture is carried out on the sandiest soils throughout the Panhandle, the loamy soils of the Western Red Hills and Tallahassee Red Hills, and the acid wetland soils of flatwoods. b. Ecology. Most of the silviculture in the Panhandle involves monospecific stands of one of three kinds of native pines: slash pine (Pinus elliotfir), loblolly pine(P. taeda),andsandpine (P. clausa). About as much acreage in the clayhill regions of the Northern Highlands is devoted to pine tree farming as in the flatwoods country of the Coastal Lowlands. Therefore, many community types, ranging from the driest longleaf and scrub oak forests downslope to the evergreen shrub wetlands bordering flatwood streams, have been replaced by uniform silviculture. This has erased natural beta diversity and simplified site-specific community structure. c. Flora. Usually slash pine (Pinus ellionii) is found on flatwoods soils or sandhill soils of the Gull Coastal Lowlands; slash or loblolly pine (P. echinata) on clayey loamy soils of the Northern Highlands; and, sometimes, sand pine (P. clausa) on sandy soils in the Gull Coastal Lowlands. Other trees that may occur insilviculturalstands are native hardwood species that either resprout from rootstocksorseedstocks left after site preparation, or seed into the site in the early years after planting with trees. In the clayhill regions of the Panhandle these are colonizing membersof the beech-magnolia forest, including especially sweet gum (Liquidambar styraciflua), laurel oak (Quercus laurifolia), black cherry (Pmnus serotina) and wateroak (Q. nigra). Later, iffires are kept out of silviculture stands, even the slowercolonizers such as pignut hickory (Carya glabra), dogwood (Cornus florida), and southern magnolia (Magnoliagrandiflora) will encroach if stands are leR alone for 40 to 50 years. In flatwoods regions, silvicultural stands become rapidly invaded by many of the evergreen shrub species that attain small tree stature, such as black titi (Cliftonia monophylla), swamp cyrilla (Cyrilla racemiflora), and sweetbay magnolia (Magnolia viginiana). Often a plethora of shrubby evergreen species encroaches as well, including fetterbush (Lyonia lucida and Leucothoe racemosa), stagger bush (L. ferruginea), large gallberry (Ilex wriacea). pepperbush (Clethra alnifolia), and St. Johnswort (Hypericumspp.). As one approaches the coast in the Panhandle, the water table rises nearer to the surface of the ground The Increased moisture greatly stimulates the groundcover, producing rank growth. Scarified wet flatwoods soils in the Panhandle are dominated by a luxuriant growth of St. Johnswort. On sandhills, site preparationdoes not eliminate sDecies of scrub oaks that occur in the orioinal xeric --longleaf pine communities. Usually the cloning species resprout from root fragments, these are turkey oak (Ouercus laevis), blackjack oak (Q marilandica), and bluejack oak (0. incana). Some shrubs found in silvicultural areas are sparkleberry ( Vaccinium arbreurn) and plums and cherries (Prunusspp.), but theclosedcanopy in pine tree forests after about 5-8 years of growth usually shades out most of the shrub species. Several herb species are common to all silviculture sites. Some of these are species of bluestem grasses (Andropogon spp.) and blackberry (Rubus spp.). It is notable that vines of the genus Smilax are also invariably present in pine tree farms.
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rlal Habitats Succession of a limited sort is obvious in pine silviculture. At first, the planted pines grow in an open prairielike environment with grasses and folbs abundant. After8-15 years, however,dependingon soils, the pine canopy closes and shades the ground so severely that often only a brown carpet of pine needles is visible on the forest floor. d. Fauna. The pine trees of pine tree farms produce resinous, acid litter that neither decomposes readily nor is readily eaten by many primary consumers. Among those that do eat the dead needles are harvestmen, which are reasonably numerous in silvicultural sites. Other insects are generally restricted to lepidopteran larvae adapted to eating pine needles or beetle larvae and adults that eat the cambium d trees. Amphibians are restricted to those species that enter silviculture sites from adjacent communities. Most notable is the southern toad (Bufo terrestris): others are the oak toad (B. quercicus), and, usually, the pinewoods tree frog (Hyla fernoralis). These eat the insects and other arthropods found in the litteror on boles of trees. Lizards are scarce because of the paucity of insects, but usually the ubiquitous anole (Anolis carolinensis) can be found at least nearthe edges of Silvicultural sites. Sometimes the eastern glass lizard (Ophisauffls ventralis) is present, and in pine tree farms in sandhills, the fence swift (Sceloporus undulatus) can be found. Snakes are almost nonexistent in pine tree farms because they feed at higher trophic levels than insects, but if a snake is to be found L most likely is the black racer (Coluber constrictor), which feedson lizards. It iscommon to see the gopher tortoise (Gopherus polyphemus) dig out of its burrow after site preparation, and gopher tortoise populationsflourish after replanting on silvicultural sites; invariably after about 10 years, when the canopy closes and shades out the valuable hefbaceous groundcover food of the tortoise, the species bewmeslocally extinct. This holdstrue fortheenlire community of herbs, shrubs, vines, insects, and vertebrates. Forthe first 5 to 10 years, a productive groundcoverflourishes and forms the basis for a rich animal food web. After canopy closure, and until clearcutting 2040 years later, the entire understory wmmunity nearly vanishes. Before canopy closure, grassland birds are wmmon and do well as both winter visitors and summer residents. After canopy closure, vely little bird life visits pine tree farms exceptthose that glean foliage, and feed in the canopy. Few species breed in silvicultural sites. Mammals are restricted to low density populations of those speciesthat normally inhabit the natural pine forest lands on which a given site is developed. Species usually include the conon rat (Sigmodon hispidus), cotton mouse (Peromyscus gossyp inus), short-tailed shrew (Blarina brevicauda), and the least shrew (Cryprodusparva). White-tailed deer (Odocoileus virginiana) use pine tree farms in early successional stages when forage is close to the ground and abundant. After canopy closure, whitetail use falls off dramatically. Other mammals usually are transients. In drift fence studies on silvicultural plots on the Apalachicola National Forest, Means (unpubl. data) trapped the rare southeastern shrew (Sorex longirostris) in a flatwood slash pine forest that was bedded. Generally, no rare, endangered, orthreatened species are restricted to pine tree farms, or even commonly found there.
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Chapter 6. FRESHWATER HABITATS 6.1 Introduction We define the freshwater habitats of Panhandle Florida as beginning where the water table first rises to the elevation of the soil surface. This usually happens at the lower sides of catchment slopes, somewhere nearthe streamvalley bottom. Habitats that are neither strictly aquatic nor strictly terrestrial are called wetlands. Downslope, water from wetlands flows in an ever increasing volume as it works ks way to the sea. As I joins other water to form larger and larger channels, the increasing volume of water and its changing physical attributes create a continuum of changing aquatic habitats. These habitats as well as ponds, swamps, and lakes are all considered in this chapter. The terms "lotic" and "lentic" are usually used in aquatic systems to refer to bodies of open water either running (lotic), such as rivers, creeks and streams; or standing (lentic), such as ponds and lakes. Wetlands that are periodically or ephemerally covered with water may be incorporated into this scheme depending on their source and period of inundation. In this particular case the term lot~c is expanded to include not only the aquatic portions of streams but their associated floodplain wetlands as well. Likewise, standing water wetlands such as swamps, marshes, and savannas which may fringe the margin of lakes and ponds are called lentic systems. The treatment of freshwater habitats will follow The ,,, S, Fish and Wildlife (USFWS) the same pattern as that in the section on terrestrial (Cowardin, et al, 1979, p. 3) defines wetlands to be habitats: freshwater habitats are considered to be ",.,lands transitional between terrestrial and aquatic aligned along a soil moisture and stream gradient. syStems where the water table is usually at or near The first freshwater habitats discussed are those the surface or the land is covered by shallow immediately downslope from dry ground, called water ... wetlands must have one or more of the wetlands, or palustrine habitats. Next, we will disfollowingthree attributes: (I) at least periodically, the CUSS Streams and rivers that form as water flows land supports predominantly hydrophytes; (2) the downhill from palustrine habitats into channels substrate is predominantly undrained hydric soils; sculpted by water in the landform. and (3) the substrate is nonsoil and is saturated with water or covered by shallow water at some time It is important to note that the slope of the during the growing season of each year." catchment valley sidewalls has a very strong influUnder the unpublished classification scheme of the Florida Natural Areas Inventory (FNAI), communities in Florida having these characteristics are classified as "palustrine." These are "...lands regularly inundated or saturated by freshwater and characterized by wetland vegetation." The FNAl list contains 19 palustrine community types of which all are found in Panhandle Florida. Below we use the FNAl designations, expand upon them where we believe it warranted, or at least mention them under our own heading. ence upon the type of wetland or stream encountered. In catchments with steep slopes cut by gully erosion, streams and the adjacent wetlands are confined to a narrow band where the two slopes intersect. The hydrology and biology of such streams is very different from streams with gently sloping valley walls. When stream catchments are not deeply etched intothe landform, such as those inthe flatwoods of the Coastal Lowlands, the wetlands adjacent to the stream form very broad fringing zones.
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6. Freshwater Habltats 6.2 Native Palustrine Habitats 6.2.1 Herb Bogs and Savannahs Much of the geological structure underlying the Florida Panhandle is deep, porous sand often containing relatively impermeable clay lenses. In combination with the high annual rainfall, this condition causes the buildup of small reservoirs of perched groundwater. Where slopes are very steep, such as those in steepheads that characteristically are 45Oor more, seepage escapes into a welldefined stream channel, and little boggy wetland exists. But where the sloping ground surface is very gentle, such as in the Gulf Coastal Lowlands (Figure 5), it intersects the horizontal water table over a fairly broad zone. Here the water seeps laterally, forming wetlands called bogs (Figure 63). The first of the wetland zones normally encountered downslope from longleaf pine forests in stream valleyswith gentle slopes, iscal1eda"seepage bog," or a "herb bog." Panhandle Florida and the adjacent lower Gulf Coastal Plain of Alabama and Mississippi were once nearly continuous bogs (Bartram 1791, Harper 1914), containing one of North America's most unusual assemblages of animals and plants, including many that are rare, endangered, or endemic. Calculations by Folkerts (1982) indicate that nearly 97%of the original herb bog habitat has been destroyed throughout the Gulf Coastal Plain. The largest acreage and some of the best remaining exampiesof thisuniquewetlandtypeare foundin the Coastal Lowlands areas in Panhandle drainage basins from the Perdido to the Ochlockonee Rivers Seepage bogs decline rapidly in both acreage and number to the east of the Ochlockonee, and are not a particularly important habitat type in the Florida Big Bend. Although defined as wetlands, seepage bogs of various types are sometimes quite dry. During periods of wet weather when the perched aquifers are fully charged, seepage is continuous and the soil of herb bogs is moist and difficun to walk in because of sinking into the wet organic deposits. At the other extreme, during seasonal or extended droughts, the soil of herb bogs tends to dry out and sometimes crack. In order to tolerate the drastic soil moisture changes animals and plants must have specific adaptations to resist death or physiological stress. Because of the activity of the mineral components of the soils, bog soils typically are low in pH. Values range from3.4to5.0 (Wharton 1977, Clewell 1981, Folkerts 1982). This, coupled with low-nutrient soils, makes bogs home to only those plants that can tolerate such extreme conditions. a. Flora. Typically, Panhandle seepage bogs contain insectivorous plants, including two or more species of Drosera, the sundews; two or more species of Sarracenia, the pitcher-plants; two or more of Pinguicula, the butterworts; and occasionally UtricuIaria, the bladderworts. Because the distinctive leaves of some species of pitcher plants are so conspicuous, these bogs are often called "pitcher plant bogs." Many other genera of forbs characteristic of highly acid sites are associated with the carnivorous plants, including Sphagnum, EriocauIon, Calopogon, Habenaria, and Burmannia. Wiregrass (Aristida stricta), beaked rushes (Rhynchospora), panic-grasses (Panicurn), and sedges are among other dominant herbs. When the seepage slopes of flatwoods stream valleys are extremely gently inclined, the herb bog zonecan be hundreds of meterswide (Figure64). In this case, the open, treeless plain often is called a savannah. The region located in the western half of the Apalachicola National Forest between the settlernentsof Wilma and Sumatrais particularly noted for extensive seepage bog savannahs developed on fine clays and silts (Ciewell 1971). Clewell (1971) has studied these savannahs and believes there are four variations: (I) Verbesinaphase. This isanopensavannah with loamy surface soils The indicator species is Chapman's crownbeard, Verbesina chapman;;, a summer flowering composite. (2) Pleeaphase. Thistoo is anopen savannah. but with sandy soil. The indicator species in the ground cover IS an autumn flowering lily, rush featherling (Pleea tenuifolia). (3) Hatrack phase. This is a less open savannah with one to many stunted slash pines (P~nus elliofti~) with spindly trunks and abbreviated limbs. (4) Pine-titi phase. This is an even less open savannah w~th some Pleea and larger slash pine, pond pine (Pinus serotina), titi (Cyrilla spp Cliftonia monophylla), cypress ( Taxodium distichurn var. nu-
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Panhandle Ecological Characterization tans), sweet bay (Magnolia virginiana), wax myrtle (Myricacerifera),fetter-bush (Lyonialucida), myrtleleaf holly (Ilex myrfifolia), and large gallberry (Ilex coriacea). This fourth phase is regarded ascontinuous with titi swamps. Were it not for the lack of saw palmetto (Serenoarepens) and the presence of pitcher-plants and othercharacteristic savannah species, the pinetiti phase could be considered transitional to till swamps. mese communities are noted for their dense growth of grasses and sedges interspersed with an abundance of wild flowers numbering well over a hundred species. Among these are many orchids and insectivorous plants. Wiregrass usually dominates although it may be absent from the Pleea phase. Species of Panlcum are also important. Beak rush (Rhynchospora chapmanii, R. plumosa) and several nut rushes (Scleria baldwinii, S. reticularis) are among the more important sedges. A pseudocanopy of St. Johnswort (Hypericum sp.) often covers the entire community. The needlelike leaves apparently allow considerable light to reach the ground cover below. The level of soil moisture insavannahsisconsistently higherthan in pine flatwoods and even in some bay communities. The heavy loams and highly organic sands are Indicative of a perched Water table. After heavy rains the soils may be totally saturated for extended periods, giving rise to the name herb bog. In addition to the ecotone between the pine-titi phase and the titi swamps, savannahs also Intergrade with savannah swamps and longleaf pine flats. Clewell (1971) summarizes the ecological relationships of savannahs to other vegetation and theories on their origin and maintenance. According to Clewell, Verbesinachapmaniigrows only in heavy soils and Pleea tenuifolia only in sands or sandy loams: they do not grow together. Barbara's-buttons (Marshalliagraminifolia) may also be a good indicator of the Pleea phase. Several other species seem to be associated only with Verbesina savannahs. The Verbesina phase isgenerallyfreerof shrubsand does not contain black titi, fenerbush, or large gallberry. The clays underlying the Verbesina phase extend downward at least 811. The proximity of these clays to the Apalachicola River suggests that they represent alluvial deposits, which accumulated as the river shined course during the Pleistocene. Ripples of sand on top of these clays provide the elevated knolls upon which longleaf pines grow. The curious hat rack slash pines may have become established during periods of fire suppression. The poorly adapted pines were able to grow sufficiently to withstand the next fire. Pritchett (1969) studied slash pine growth in a savannah having a weston fine sandy loam, which is a humic gley soil. He found that the poor drainage caused by a sandy clay substrate within 25 cm of the surface, reduced the aeration neededforgrowth in pine roots. Healso found that low levels of phosphorus restricted growth. Applications of phosphate on an unditched site with minimal site preparation raised the site index (a numerical evaluation of the quality of a habitat for plant productivity used by the U.S. Forest Service) from 28 to 68 The question has been raised whether southeastern savannahs are successionalpermanent, or artifactual communities. Penfound (1952) suggested that savannahs could be created by excessive fireor logging. Wells and Shunk (1928,1931) in a classic study on a savannah in North Carolina noted that nearly all savannah vegetation grew on hammocks which they believed to be the soil around former root systems in a shrub-bog of blackgum (Nyssa sylvafica) and swamp titi (Cyrilla facemiflora). With a drop in the water table in postPleistocene times, the savannah replaced the shwb-bog, at least in part because ot increase in the incidence of fire associated with a drier habitat. Pessin and Smith (1 938) noted that the logging ot longleat pines resulted in a higher water table in successive years and in a subsequent invasion of pitcher-plants and other savannah species which had been absent previously. They suggested that removing the trees reduced the evapotranspiration sufficiently to raise the water table, or rather to prevent its being lowered. Wahlenberg (1946) expressed the same opinion on savannah formation. Quintus A. Kyle (pers. comm. to Clewell 1971) added substance to that theory. He said that some
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6. Freshwi of the present savannahs west of Bradwell Bay in the Apalachicola National Forest (ANF) were formerly low, wet longleaf pine flatwoods that were not as densely stocked as pine-palmetto flatwoods usually are. These pines were cut in about 1915. and thereafter the water table rose and savannah vegetation became evident. It seems likely that the acreage of savannahs has increased since the initial logging in the ANF. If so, much of the Pleea phase may have once been low flatwoods, which are now being converted to savannah because of a rise in the water table. The pine-titi phase would then represent additional areas being converted to savannahs, but lack of fire has allowed the invasion of brush. Wells and Shunk(1928) noted the complete lack of legumes in a savannah in North Carolina. Legumes are rare or absent in savannahs of the ANF, although many species are represented, some abundantly, in adjacent pinelands. Perhaps the nitrogen-fixing bacteria in leguminous roots cannot survive the long hydroperiods of savannah soils. Wells (1967) remarked on the large number of species with leaves appressed against their stems, which he interpreted as a mechanism to prevent transpiration. Plants of savannahs may be physiological xerophytes, even though they grow in wet soils, because high acidity prevents the rapid absorption of water. Of course the reduction in evapotranspiration is not necessarily theonly mechanismfor raisingwater tables and thereby creating savannahs. Clewen (1971) suggested that slumping of the surface could be creating wet depressions as organic acids dissolve calcareous deposits in underlying Miocene nlactirc b. Fauna. As expected in a plant community lacking trees and shrubs, no arboreal fauna is present. The herb-dominated bogs and savannahs of the Panhandle support a rich diversity of insects that feed upon the numerous species of groundcover plants. These in turnfeed asmall groupof vertebrate . --. insectivores, including most notably the pine woods The Verbesinasavannahs lack pine stumps, but adjacent longleaf pine flats still retain stumps remainingfromthe original timber harvest. This observation suggests that the Verbesina phase is a permanent, edaphic vegetation type, and was not created via recent reductions in evapotranspiration. The heavy soils probably retain water much more effectively than sands. Evidence for this comes from a somewhat loamy savannah of the Pleea phase near Fort Gadsden (SW 114 Sec. 29, T6S R7W), where the savannah is actually afoot or so higher in elevation than the adjoining, sandier, drier pinepalmetto flatwoods (Clewell 1971). Changes in savannahs in northwest Florida resulting from disturbance were indicated by Pullen and Plummer (1961). They resurveyed a savannah studied in 1906 by R. M. Harper, which had since been drained and intensively grazed. They counted 98 species not listed by Harper, many of them weedy, that were introduced because of disturbance. They also said that about 50 species had been eliminated, including spectacular species of pitcher-plants (Sarracenia spp.), sundew (Drosera spp.), Agalinis, Aster, Coreopsis, colic-root (Aletris spp.), meadow-beauty (Rhexia spp.), cone-flower (Rudbedia spp.), Sabatia spp., and Balduha spp. tree frog (Hyla femoralis), the ornate chorus frog (Pseudacrisornata), and the Florida chorus frog (P. nigrita). Burrowing crayfishes of the genera Carnbarus and Procambarus (Hobbs 1942) can be unusually abundant in herb bogs. Although never studied, it appears quite probable that burrowing crayfishes have a strong beneficial influence upon other animals that use the burrows for protection from enemies and the elements. Among these species are the two-toed amphiuma (Amphiuma means), southern dusky salamander (Desmognathus auriculatus), and the mud salamander ( Pseudotriton montanus) In the western Panhandle from Washington to Santa Rosa Counties, the pine barrens tree frog (Hyla andewonfl seems to be exclusively dependent upon herb bog seepage sites for breeding (Means and Longden 1976, Means and Moler 1979). Reptiles that use herb bogs include the garter, ribbon, and mud snakes (Tharnnophis sirtalis, T. sauritus, Farancia abacura). The mud turtle (Kinosternon subrubrum) and box turtle ( Terrapene carolina) are also common herb bog inhabitants. Grassland birds like the meadow lark (SturneNa magna) and the red-winged blackbird (Agelaius
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Panhandle Ecologlcal Characterization phoeniceus) are vislors in herb bogs occasionally and the common yellowthroat (Geothlypis trichas) is found along shrubby edges. The rice rat (Oryzomys palustris) and cotton rat (Sigmodon hispidus) are important and common small mammals that live in herb bogs, the rice rat being more at home during wet weather when the bogs are wet, and the cotton rats more so during drought. 6.2.2 Shrub Bogs, Titi Swamps, and Bay Swamps Downslope from herb bogs, a dense growth of evergreen shrubs is encountered in Panhandle flatwoods. When fire cycles are operating normally, the transition from open herbaceous prairie to dense. smalland leathery-leaved shrubs is often abrupt (Figure 63). Predominant among these shrubs are the titis of the family Cyrillaceae, with either black titi (Cliftonia monophylla) or swamp titi (Cyrilla racemiflora), or both, present. Other evergreen shrubby species usually present with the titis are the fetterbushes (Lyonia lucida and Leucothoe racemosa), myrtles (Myrica cerifera and M. inodora), dahoon holly (Ilexcassine) and large gallberry (I. coriacea), sweet pepperbush (Clethra alnifolia), and others. In Panhandle Florida evergreen shrub communities of this type usually fringe swamp forests of several types. The shrub zones are rarely extensive, but form a very distinctive transition from the dry soil uplandsormoist soil herbbogstothestreamorpond gallery forests described below. P~ne flatwoods are frequently dotted with swampy depressions and minor drainageways occupied by shrub-bog speciesand small trees, mostly evergreens. Such systemsare loosely referred to as "bays" or "bay swamps." These swamps may support primarily titi (Cyrilla racemiflora, Cliftonia monophylla), inwhichcasethey arecalledtitiswamps. Titi swamps may contain scattered pond pines (Pinus serotina) or slash pine (P. ellionir) extending above a dense growth of titi. Small, round bay or titi swamps of a few acres or less are locally called ponds, even if they contain no standing water. Larger bay swamps usually contain taller trees toward the centerand arefringedwith titi. Sweetbay magnolia (Magnolia virginiana) and slash pine are common species. Where such swamps form the headwaters of a small creek, they are known as 'bayheads." Intermittent streams lined with elongated bay swamps are known as bay branches. Where Atlantic white-cedar (Charnaecyparis thyoides) growsconspicuously within bay ortiti swamps the area is locally called a juniper swamp. Large bay swamps may also encircle moister sites occupied by cypress or blackgum swamps. Cypress swamps that are circular in shape are known as cypress domes or heads because the trees in the center tend to be taller than those along the margins, giving a circular dome shape to the canopy. The center trees may be taller because conditions there are more optimum for cypress growth than the margins. Elsewhere in Florida. researchers have noted that the taller trees in the center may ormay not beolderthan thefringingtrees (Duever et al. 1976). Kurz (1933b) hypothesized that the shape of cypressdomes wascreated by the pruning effect of fires. Shorter, youngertrees would be produced at the margins by more frequent fires there, and larger, tallertrees would result fromfewer fires as one moved toward the deeper water in the center of domes. Cypress swamps that are elongated along a slough or other small drainageway are called cypress strands. Within large areas of bay, cypress, or blackgum swamps, small patches of pineflatwoods may occur. These pine islands usually occupy the more elevated sites. The ecotonal changes from pineland to tifi, bay, cypress, and blackgum swamps usually involve an elevationdrop of less than 4 m (12ft). The horizontal distance may be as small as 1666 m (50-200 ft). Below this point or as the size of the swamps increase, the community type changes to bottomland hardwood forest or cypress-gum swamp forest. a. Bay swamps. Clewell (1971) identified four phases of bay swamps: (1) Sweetbay phase where sweetbay (M. virginiana) is dominant with a few slash pines, swamp bay (Persea borbonia) and loblolly bay (Gordonia lasianthus); (2) Slash pine phase, with sweetbay present but slash pine dominant; (3) Mixed swamp phase, with dominance shared by sweet bay, blackgum, cypress, sweetgum (Liquidambar styraciflua), red maple (Acer rubrum), wateroak(0uercus nigra), anddiamond-leaf oak (0.
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6. Freshwater Habltats laurifolia); and (4) Atlantic white cedar phase, as mentioned above; Atlantic white cedar (Chamaecyparis thyoides) is aconspicuous member of the community. The patchy, often dense understory of bay swamps contains a mixture of switch cane (Arundinaria gigantea), wax myrtle (Myrica cerifera), swamp titi (Cyrilla racemiflora), sweet pepperbush (Clethra alnifolia), and black titi (Cliffoniamonophylla). Other common species include wild azalea (Rhododendron canescens), fetter-bush (Lyonia lucida), large gallberry (Ilexcoriacea), muscadine (Vitis rotundifolia), myrtle leaf holly (I. my~tifolia), odorless wax myrtle (Myrica inodora), climbing fetterbush (Pieris phyllyreifolia), an epiphytic shrub on pine orcypress, red chokeberry (Aronia arbutifolia), highbush blueberry (Vaccinium corymbosum), odorless yellow jessamine (Gekemium rankinif), and poison ivy ( Toxiwdendron radicans). Ground cover consists of patchy beds of peat moss (Sphagnum spp.), Virginia and netted chain ferns ( Woodwardia virginica, W. areolata), sedges (e.g., Carexglaucescens), and grasses (e.g., Panicum tenerum). Cane (Arundinaria gigantea) may occur in openings. The soil in bay swamps is highly organic sand often overlain by peat. The peat may erode into hammocks and hollows giving some microrelief to the terrain. The soil is usually moist and attimes may be inundated with several inchesof water. The water table seldom lhes more than 1 m below the ground level. Pinesare not common in bay swamps primarily becauseof thewetness and the bufferprovidedby frlnglng tlt~ swamps. b. Tltl swamps. Titi swamps come in five varleties, threeof which have a pine overstoly: (1) Atiti phase with no overstoiy of pines, (2) A pond pine phase, (3) A slash pine phase, (4) Apond pine-slash plne phase, and (5) A holly phase with neither a pine overstoiy nor titi, having myrtle-leaf holly as the dominant shrub. Atlanticwhite cedar may be locally common. This community is distinguished by its understory of dense shrubbery. The dominant species include one or more of two titi species, black titi (Cliftonia monophylla) and swamp titi (Cyrilla racemiflora). Black tiii is the most common and tends to occuronhighersitesthanswamptiti. Othercommon species of shrubs include fetter-bush, large gallberry, and switch cane. Less common but still frequent species include staggerbush (Lyonia ferruginea), sweet peppetbush (Clethra alnifolia), and odorless wax myrtle. Ground cover is generally absent. Saplingsof swamp bay or sweet bay may be present. Soils in tiii swamps are similar to those in bay swamps: highly organic sand overlain by peat. Generally the mots of the shrubs bind the peat soils, but under the influence of fire and intense rainfall erosional channels may develop, leaving liitle islandsof thickerpeat between swales burneddown to mineral soils. As in bay swamps the water table is always close to the sudace. During wet periods standing water pockets are common. Tiii swamps often border on pine flatwoods and may form along the borders between bay swamps and pine communities as well. Titi swamps tend to be poor fuel for the frequent fires that maintain pine dominance in neighboring flatwoods. Usually no more than the outerfringesof titi swamps bum. Thus they act as aprotective buffer between pinecommunities and more fire sensitive bay swamps. In places the titi swamp may also border cypress or blackgum swamps, affording them the same buffer. During prolonged summer dmughts when humidity is low and the water table depressed, fire may spread into the titi swamps or be started there by lightning. Clewell (1971 ) estimated these conditions could occuronce every 5 to 10 years. Wharton et al. (1976) estimated that the fire period in titi swamps was 20-50 years in monospecific standsof black titi. When such fires do ignite, they tend to be very hot and hard to contain. Usually all aerial stems are destroyed and some or all of the peat may also burn. Larger pines if present may survive, but most of the trees and shrubs will be killed if fires bum deeply into the peat and kill their roots. Subsequent to fires that do not burn into the peat, the titi and other sh~bs resprout from root crowns, directly regenerating the swamp without going through successional stages. Often several
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Panhandle Ecologlc a1 Characterization sprouts may arise from each crown, creating trees and bushes with multiple trunks. It has been suggested that the root crowns of these multitrunk resprouted trees and shrubs may be centuries old (Clewell 1971). Titis (Cyrillaceae) are but one group of evergreen shrubs or small trees that in the pre-Columbian Coastal Plain naturally occurred downslope from the fire-frequent longleaf pine forest in places where soil moisture was high enough to preclude fires in most normal years. The titis and the other evergreen woody species associated with them are fire-tender hardwoods that die when their stems are heated. The evergreen shrub zone naturally occurs just upslope along the margin of stream hardwood forests occupying creek bottoms where stream valley soils usually are saturated. This was the narrow, original zone of slash pine, also. When fires are kept out of the flatwoods in the Coastal Lowlands for long periods of time, as they have been in Florida National Forests by anthropogenic factors, the evergreen shrub species of stream hardwoods migrate upslope by seeding and mot propagation. This has atwofold effectupcnthe ecology of the herbaceous wetlands. First, the vegetative species wmposition obviously changes, and so too does the vegetative structure. Instead of a grass-forb meadow habitat, the herb bog sites become closed-canopied forests of small-diameter, densely stocked evergreen trees. Because woody plants have higher evapotranspiration rates than grasses and fobs, the sheet flow that occurs in heb bogs due to seepage from the intercepted water table is depressed, changing the hydrology of the site. In flatwoods where drainage valley slopes are so gentle that they often cannot be perceived by the naked eye, the woody evergreens and other stream hardwoods expand their distribution well upslope into the longleaf-wiregrass zone. Site preparation probably is more damaging ecologically in titi areas that are to be reclaimed than in any other soil type because the delicate, gentle slope and moisture gradients are severely interrupted by chopping, disking, and bedding, and by running a fire plow through them, channelizing the water flow. c. Fauna. The animal life of shrub bogs has not been the target of specific studies, but many Panhandle animals are known to use shrub bogs. Two frogs seem to be restricted almost exclusively to shrub bogs and the adjacent herb bogs. One is the pine barrens tree frog, Hyla andersonii, which uses the stems of evergreen shrub plants as foraging habitat (Means and Longden 1976. Means and Moler 1979). Theotheristhe bogfrog (Ranaokaloosae), known from wetlands along the margins of the steephead streamsof Eglin Air Force Base and afew localities in Santa Rosa, Okaloosa, and WaltOn counties (Moler 1985 and P. Moler, Florida Game and Fresh Water Fish Commission. Gainesville; pers. comm.). When enough water is present for breeding, shrub bogs also support populations of the bronze frog (Rana clamitans), southern leopard frog (R. sphenocephala), green tree frog (Hyla cinerea), plne woodstreefrog (H. femoralis), and springpeeper (H. crucifeer). The five-lined skink (Eumeces fasciatus) and sometimes the coal $kink (E. anthracinus) are common lizards while the green anole (Anolis carolinensis) and ground skink (Scincella lateralis) are sometimes abundant at tne margins of shrub bogs. Galter snakes (Tharnnophis sirlalis) and ribbon snakes (T. sauritus) forage in shub bogs for frogs, as does the black racer (Coluberconstrictor) and the endangered indigo snake (Drymarchon corais). 6.2.3 Bottomland Hardwood Forests The forested floodplain of the Apalachicola watershed is the largest in Florida, covering approximately 450 km2 (173 mi2) (Wharton et al. 1976). The predominant species in terms of cover include water tupelo (Nyssa aquatics), ogeechee tupelo (N. ogeche), baldcypress ( Taxodium distichurn), carolina ash (Fraxinus caroliniana), swamp tupelo or blackgum (Nyssa syhratica biflora), sweetgum (Liquidambar styraciflua), and overcup oak (Querws lyrata). These species are typlcal of alluv~al floodplains in the southeastern United States and occur in such areas partially because of their ability towithstand saturated and inundated soils (Wharton et al. 1976). The distribution of floodplain trees in the Apalachicola basin has been described in detail by Leitman (1978,1984) and Leitman et aI. (1983). lnthese studies vegetative wmposition was shown to be
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6. Freshwater Habltats Table 12. Types, specles composltlon, and dlstlngulshing characterlstlcs of bottomland hardwood forests of the Apalachlcola River (from Leltman et al. 1983). Name Deflnltlon Chlef associates Common associates Type A: Sweetgum Sweetgum, sugarberry, Diamond-leaf oak, American elm, sugar-berry-water water oak, American green ash. American sycamore, oak. hornbeam, possumhaw, water hickory. are predominant." Type B: Water hickoryWater hickory, green Sugaberry, red maple. Water oak, possumhaw, green ash-overcup ash, overcup oak, American hornbeam, oak-diamond-leaf diamond-leaf oak, water tupelo, Ogeechee oak. sweetgum, American tupelo, baldcypress. elm are predominant." Type C: Water tupele Water tupelo, OgeeOvercup oak, pumpkin Water hickory, Ogeechee tupelochee tupelo, baldash, red maple. American elm, green baldcypress. cypress, swamp tupelo, ash, diamond-leaf oak, Carolina ash, planertree sweetbay. are predominant but not pure." Type D: Water tupelcWater tupelo, swamp swamp tupelo. tupelo, Ogeechee tupelo, baldcypress, Carolina ash, pumpkin ash. planertree. sweet. bay are Type E: Water tupeloWater tupelo, baldbaldcypress. cypress, Ogeechee tupelo, Carolina ash, planertree are pure." Predominant: comprising 50% or more of basal area; pure: comprising 95% or more of basal area. bSwamp tupelo, pumpkin ash, or sweetbay serve as Indicator species to distinguish this type from type E. highly correlated with depth of water, duration of inundation and saturation, sediment grain size, and water level. These hydrologiccondiiions are, inturn, controlled by the height of natural riverbank levees and the size and distribution of levee breaks along the river. A description of forest types, their species composition, and distinguishing characteristics is presented in Table 12 from transect plots surveyed by Leitman et al. (1983). Alluvial rivers have broad floodpla~ns that are dominated by two very important hydrological processes: high water and low water. During low water stages, the water flows in a meandering channel that, with time, wanders back and forth across the floodplain and continually resculpts it. The scouring action of water at the outside bends of meander loopscontinually undercuts thechannel bank, causing the stream channel to migrate in the direction of
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Panhandle Ecological Characterlzatlon the meander loop. Sediment eroded from the outside bends of meander loops is deposited downstream on the inside of the next bend in the 'ver, on the advancing end of the point bar. Point bars have successional stages of plant communities developing on them from the youngest pioneer stages on new sand berms at water's edge to stable hardwood forests farther back from the water. When risingwater leavesthe low-waterchannel, it loses its velocity--and thus its sediment carrying power--creating piles of coarser sediments called levees, or berms, along the channel banks. The coarser sediments are dropped first, and finer sediments such as silts and clays are carried farther out into the floodplain. It is not uncommon for sill and clay several inches to afewfeet deepto bedeposited on the floodplain floor away from the low water channel after every high water rise. Each Panhandle river has its great annual rise sometime between midwinter and midspring (January to April), when water volume may exceed 100 times or more the normal volume in the low water channel (Foose 1983). During this 3-month period, water extends across the entire floodplain from one valley sidewall tothe other. Only flood-tolerant species of plants and animalscan survive infloodplains. Floodplain communities, therefore, are true wetlands, characterized by specialized wetlands species. TN~ terrestrial vegetation is found above the level of the annual high water at the extreme lateral margins of the floodplain. The inundated floodplain of the Apalachicola River during the annual high water levels ranges from 2300 m (1.4 mi) to 6500 m (4 0 mi) wide (Leitman et al. 1983). The Apalachicola River floodplain remains inundated annually for periods ranging from 1 to 5 months (Foose 1983). a. Ecology. A sweetgum-water oak-loblolly pine (L~quidambar styraciflua-Ouercus nigra-Pinus taeda) association is found in dry to damp soils on elevated slopes. This forest association is most prevalent in the middle reach of the river, decreasing in area as the water hickory-overcup oak-sugarberry (Carya aquatics-Ouercus lyrata-Celtis laevigata) association Increases. This association covers approximately 43% of the floodplain, mainly in the upper and middle reaches of the river basin, and becomes ~ncreasingly uncommon in the lower reachesofthe rivervalley where it occupies anarrow band along the riier. Dominant in the lower reaches of the river basin is a tupelo-cypress-mixed hardwood association covering over 38% of the lower floodplain. Found in dry to saturated soils, this association is concentrated along existing and relict waterways just upland from the water hickory-overcup oak-sugarberry association. A somewhat similar tupelo-baldcypress (Nyssa aquatics-Taxodium distichurn) association is located in damp to saturated soils along the entire length of the river. In additionto these major forest associations a pioneer community, dominated by black willow (Salix nigra), occupies a narrow zone in areas inundated more than 25% of the time. When all forest types are considered, tupelo, baldcypress, and ash (Fraxinus spp.) are the three most abundant species in descending order (Table 13). Total leaf production follows the same general ranking withonly afew exceptions (Elder and Cairns 1982). It is surprising, however, that relative leaf production per stem biomass of individual tree species displays adifferent trend. Low abundancetrees such as sugarbeny, overcup oak, American hornbeam (Carpinus caroliniana), and elm (Ulmus spp.) are high in relative leaf productivity while tupelo, cypress, and ash are low (Figure 65). Although no ex~lanation for this has been advanced. it seems pdssible that trees occurring in saturated (and anaerobic) soils such as tupelo, cypress, and ash may be nutrient limited or may be investing energy instem and trunk biomass. The expanded basal areas of these trees relative to other tree species strongly suggest that they invest more than an average amount of energy into stem and trunk biomass production, perhaps to aid in stabilization. This may bedone at the cost of leaf production. Incontrast, the more upland species can afford greater leaf production which may improve their competitive ability for light and canopy space. The higher rates of leaf production may resuitfrominvesting less energy in stem and t~nk biomass and perhaps from higher nutrient concentrations. Aplot of total leaf production versus hydroperiod would yleld a bell-shapedcurve according toproductlvny data of Elder and Calrns (1982) At the peak of this curve is a forest characterized by high tree species diversity and low to moderate inundation. Although speculative, this peak in leaf production
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6. Freshwater Habltats Table 13. Specles abundance for all forest types comblned (from Leltman et al. 1983). Specles are ranked In order from most lmportant to least Important In terms of basal area. Absolute basal area and density upon whlch these percentages are based are 201 R21acre (46.2 rnYha) and 623 trees lacre (I ,540 treeslha), respectively. Because of rounding, percentages given will not necessarily total 100. Species Relatlve basal area (%) Relatlve denslty (%) Water tupelo (Nyssa aquatics) 29.9 12.8 Ogeechee tupelo (Nyssa ogeche) 11.0 6.6 Baldcypress ( Taxodium distichurn) 10.6 5.5 Carolina ash (Fraxinus caroliniana) 5.4 11.5 Swamp tupelo or blackgum (Nyssa sylvatica biflora) 5.0 2.0 Sweetgum (Liquidambar styraciflua) 4.8 3.2 Overcup oak (Ouercus lyrata) 3.2 2.0 Planertree' (Planera aquatics) 2.9 9.4 Green ash (Fraxinus pennsylvanica) 2.9 2.7 Water hickory (Carya aquatics) 2.9 0.8 Sugarberry or hackberly (Celtis laevigata) 2.8 2.1 Diamond-leaf or laurel oak (Quercus laurifolia) 2.5 1.4 American elm (Ulmus americana) 2.4 1.2 American hombeam (Carpinus caroliniana) 2.0 4.7 Pumpkin ash (Fraxinus prof~nda)~ 1.9 4.4 Water oak ( Ouercus nigra) 1.8 0.5 Red Maple (Acer rubrum) 1.5 4.8 Sweetbay (Magnolia virginiana) 1 .O 0.5 River birch (Betula nigra) 0.8 0.7 Possumhaw (Ilex decidua) 0.8 10.5 American sycamore (Platanus occidentalis) 0.6 0.3 Swamp cottonwood (Populus heterophylla) 0.4 0.4 Black willow (Salix nigra) 0.4 0.4 Swamp chestnut oak (Quercus prinus)c 0.3 0.1 Box elder (Acer negundo) 0.3 0.8 Other species found: Green haw (Crataegus viridus) Buttonbush (Cephalanthus occidentalis) Cabbage palmetto (Sabalpalmetto) Spruce pine (Pinus glabra) Water locust (Gleditsia aquatics) Loblolly pine (Pinus taeda) Red mulberry (Morus mbra) Buckthorn bumelia (Bumelia lycioides) Swamp-privet (Forestiera acuminata) Parsley haw (Crataegus marshalli~) Winged elm (Ulmus alata) Common persimmon (Diospyros virginiana) Slippery elm (Ulmus rubra) Black walnut (Juglans nigra) Cherrybark oak (Ouercus falcata var. pagodaefolia) Titi (Cyrilla racemiflora) Stiffcornel dogwood (Cornus f~emina)~ Witherod viburnum (Viburnum cassinoides) Chinaberry (Melia azedarachy Little silverbell (Halesia pawiflora) Black tupelo or sourgum (Nyssa sylvatica') Plus a total of 22 additional species. a Water elm according to Little (1979). hSome trees identifled as pumpkin ash may have been Carolina ash or green ash. Samaras (winged seeds) had dropped from the trees and seeds of all three species were mixed on the ground beneath the trees. "uercus michauxiiaccording to Little (1979). Swamp dogwood (Cornus str!cta) according to Llttle (1979). Introduced exotic species
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Pan handle Ecolog Ical Characterization may reflect the location of optimum conditions for floodplain forest growth. Further upland, forest productivity may be limited by competition for canopy space, nutrients, and less than optimum hydroperiod; closest to the river, productivity may be limited by the physical and chemical stresses of the increasing hydroperiod. This possibility is reminiscent of the theoretical maximum proposed for mangrove forest productivity within the freshwater to saline gradient (Carter et al. 1973). 300 n L a a, )r L % 250 cu 2 lQ a 03 2 200 The rate of leaf and litter production varies not only seasonally, but also as a function of forest type, individual species, and background conditions. Three patterns of seasonality are identified by Elder and Cairns (1982). The first pattern is one of high rates of leaf fall in September through December, followed by no leaf fall through late spring and only minimal rates in summer. Representative species exhibiting this pattern include water hickory, baldcypress, ash, American elm, grape (Vjtjs rofundifolia), and American hornbeam. A second pattern of leaf fall is represented by tupelo and sweetgum. These trees begin to shed leaves in the early spring and steadily increase the rate through late fall. By midwinter no leaves are falling. The third pattern is exemplified by diamond-leaf oak (Quercus laurifulia), overcup oak, sugarberry, and planer tree (Planera aquatics). These species start shedding leaves in early fall followed by a sustained release that peaks in December and January. During spring the rate decreases and by May or June leaf fall has ceased. Examples of these seasonal leaf fall patterns for three representative species are shown in Figure 66. I I 1 I I I I 4 Su Data points identified by species: *O Su Sugarberry 0 Overcup Oak H American Hornbeam H -' S Sweetgum W Water Hickory C Baldcypress A Ash T Tupelo [r: Y = 189X (-.36) n r2r o 834 L T E American Elm P Planertree D Diamondleaf Oak w 50L I4 W [r: 0 I I I I I I I 0 4 8 12 16 20 24 28 BASAL AREA (m2/ha) Figure 65. Relative leaf productivity per stem biomass of 11 major leaf-fall producers (trees) in the Apalachicoia River flood plain (Elder and Cairns 1982).
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6. Freshwater Habitats 1 WATER HICKORY 1 DIAMONDLEAF OAK 1979 1980 Figure 66. Mean monthly leaf fall of three representative species of intensive-t ransect plots in Apalachicola River flood plain (Elder and Cairns 1982). Once on the forest floor, the rate of decomposition varies with species, environmental conditions, and the supply of chemical substance (i.e., nitrogen, phosphorus, carbon). Of five tree species monitored on continuously flooded sites, tupelo and sweetgum leaves degrade the fastest, losing essentially all of their biomass in 6 months. Baldcypress and diamondleaf oak degrade the slowest losing only 40% of their biomass in the same time period. Water hickory is intermediate in decomposition rate, and it is the most variable, with 25Yr30% remaining after 6 months. On dry sites, decomposition rates are considerably lower, though the relative species rankings remain the same. The fast decomposers have approximately 60% remaining after six months, the slow ones 90%. It appears that inundation by flood waters increases the decomposition rate, a finding similar to that reported by Heald (1 969) for red mangrove leaves. Another factor controlling decomposition rate is the physical-chemical nature of the water and soil. The rate of loss of carbon, nitrogen, and phosphorus from litter are slowest in the floodplain, higher in river water, and highest at submerged locations influenced by estuarine waters. Phosphorus and nitrogen decline exponentially, with phosphorus being lost more rapidly. Carbon and total leaf material show a linear rate of decrease (Figure 67). Apalachicola floodplain forests are an important source of energy to the river and estuary. The quantity of nutrients generated from litterfall is more than that from any other source except the upstream drainage basin (i.e., Flint and Chattahoochee Rivers). What makes the floodplain source even more important is the form in which it supplies nutrients, as particulate matter. Although the upstream basin may supply a greater load of nutrients, the bulk of this energy is in the dissolved form. Lake Seminole acts as a large settling basin for particulate matter, lowering the load delivered downstream. This causes partially decomposed leaves and other forest litter from floodplain forests to take on a relatively more important role in the metabolismof the estuary (Elder and Cairns 1982). Considerable evidence indicates that detritus in particulate form is essential to maintaining high levels of estuarine productivity (Livingston 1984). b. Fauna. The floodplains across the Panhandle are richly endowed with animal life to match their plant species-richness. Productivity available to herbivores in floodplain forests is mostly in the canopy overstory. There, a wealth of consumer insects abounds that feed on the many kinds of leaves, mostly of palatable hardwood species. Feeding on the insects is a rich avifauna dominated by wood
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Panhandle Ecological Characterization Water Hickory 0 Diamondleaf Oak A Baldcypress A Tupelo Sweetgurn I I oo j 0 0 1 I 2 I I I TIME, IN MONTHS 3 4 5 6 TIME, IN MONTHS Upper River I Upper R~ver -Lower River A Estuary A Flood Plain a (above water) W a W 0 1 2 1 I 3 4 5 6 1 2 3 4 5 6 0 TIME, IN MONTHS TIME, IN YEARS Figure 67. Decline in carbon, phosphorus, nitrogen, and total leaf mass during decomposition in Apalachicola River system (Elder and Cairns 1982). warblers, many of which breed in these bottomland forests and in no other terrestrial habitats. The parula warbler (Parula americana) is one example. The only reptile that capitalizes on the canopy insects is the ubiquitous broad-headed skink (Eumeces laticeps) On the floodplain floor, notwithstanding the lack of primary productivity, a rich fauna exists which is based on (1) decomposing litter from the canopy above, (2) imported litter from tributary streams, (3) nut and seedfall from overstory trees such as sweetgum, water hickory, tupelo gum, blackgum, diamondleaf oak, overcup oak, and others, and (4) the sparse herbaceous groundcover that exists on heavily filtered sunlight. Harvestmen, millipedes, springtails, isopods, and other macroinvertebrates feed directly on the detritus and are themselves food for litter-inhabiting insectivores. Panhandle floodplains are the home of some vertebrate insectivores that are found only in floodplains. These species eat both litter consuming invertebrates and the surprising number of canopyinhabiting invertebrates that fall to the forest floor. Among these are Fowler's toad (Bufo woodhousii fowler/) upland chorus frog (Pseudacris triseriata) northern cricket frog (Acris crepitans), southern
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6. Freshwater Habltats dusky salamander (Desmognathus auriculatus), mud salamander (Pseudotrifon montanus), onetoed salamander (Amphiuma pholetef), and coal skink (Eumeces anthrocinus). The American beaver (Castor canadensis), once nearly extirpated from Florida, now is found throughout Panhandle floodplains. Its diet consists of loblolly pine, sweetgum, silverbell (Halesla dip tera), sweetbay, and ironwood (Carpinus caroliniana, predominantly, but other plants employed to one degree or another are tupelo (Nyssa spp.), box elder (Acer negundo), wax myrtle (Myrica cerifera). witch-hazel (Hamamelis virginiana), spruce pine (Pinusglabra), and others. Beavers are responsible for damming up small strearns by creating stick and mud dams across them. In the Panhandle, beaver ponds are commonly found inthe abundant water in backswamps, floodplain creeks, and sloughs of the larger river bottomlands. The eastern wood rat (Neotoma floridana) is common in hardwood bottomlands (Lowery 1974), building large stick and debris nests often on bare ground at the base of a tree, in a hollow log, or especially under tangles of muscadine vines (Vitis spp.). This rodent is one of the commonest herbivores in bottomland hardwood forests, eating buds, seeds, tubers, roots, nuts, succulent herbs, grasses, berries, and especially oak mast. 6.3 Native Riverine Habitats There has been very little effort to make comparative studies of the streams and rivers of Florida. Furthermore, there are very few intensive studies of the ecology and limnology of any Panhandle Florida river. We have been unable to find any ecological characterization of the physical, chemical, and biological properties of Panhandle rivers. What knowledge is available resides in many separate studies of single species or specific water quality and hydrology studies. Beck (1 965) made an admirable early attempt to analyze Florida streams and delineate the natural categories he felt they represented. For our purposes, the streams and rivers of Panhandle Florida are loosely organized into three categories, following Beck (1965): (1) alluvial streams, (2) blackwater streams, and (3) spring-run strearns. Streams and rivers of the Panhandle, however, while mostly exhibiting the characteristics of one of the above categories, infact also possesscharacteristiwofthe other two streamtypes. The large, alluvial Apalachicola River for instance, blends its waters with the Chipola River, its largest Florida tributary and a spring-run stream. Another example is the alluvial upper Ochlockonee Riverwhich joins the blackwater stream. Telogia Creek. Unfortunately no student of Florida's Streams has made a study of the changes that occur with increasing watervolume, showing, for instance, how the ecology of streams may changeand beclassified along awatervolume gradient. Clearly the limnology at the source of a steephead seepage stream differs in the extreme from that of the middle of the Apalachicola River. When speaking of the size of a stream, we refer to the same stream classification scheme (Figure 60) we referred to when describing the upland vegetation alonga streamvalleygradient (Strahler 1964). 6.3.1 Flrst-order Ravlne Streams Just as the vegetation and animal life in the terrestrial ponion of ravine valleys is distinctive from all other types of upland habitats, the biota of the water column in ravines is very different from other types of aquatic systems. No specific comparative studies of the limnology of Panhandle Florida ravine waters has been carried out, but numerous studies of aquatic invertebrates, and afew studies01 aquatic vertebrates, indicate that ravine streams form a special class of aquatic habitats. Moreover, there may be different types of ravine streams as well. Studies of crayfish (Hobbs 1942), freshwater snails (Thompson 1984), mayflies (Berner 1950), dragonflies (Byers 1930), water beetles (Young 1954), caddisflies (Franz 1982), stoneflies (Stark and Gaufin 1979), and salamanders (Means 1974a,b, 1975: Means and Karlin, in press) indicate that ravine-type headwater streams in the Panhandle are llnique aquatic habitats having a specialized fauna of their own. There are good reasons also why ravines of a special type called steepheads (see Chapter 5.2.4) may have entirely different aquatic
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Panhandle Ecological Characterlzatlon life than ravines formed by gully erosion (Chapter relatively rare in Florida, and which lives mostly in 5.2.3) (Means 1981, 1985~). Panhandle ravine streams. Occasionally, banded water snakes (Nerodia fasciata) find their way into a. Flora. Little is known of the aquatic subravine streams, probably to eat fish. The mud turtle mergedvegetationof Panhandle ravine streams, but (Kinosternon subrubrum), loggerhead musk turtle algae and diatoms are commonly visible to the (Sternotherus minorj, and juvenile snapping turtles naked eye or using a hand lens, growing on the pea(Chelydra serpentina) all forage in ravine stream sizedgravelsandcoarsesandsinsteepheadstream Waters (Means, personal obsewation). Panhandle beds. Primary productivity in these streams is most Florida ravine streams apparently have no aquatic likely somewhat limited because the streams are almost always heavily shaded by aclosed hardwood canopy. Productivity derives mostly from litter that falls orwashes into ravine streams from the productive hydric hardwood forests of the stream valley bottom (Magnolia virginiana, lllicium floridanum. Smilax bona-now), and the mesic hardwood forests clothing the lower valley sidewalls. These latter forests usually are the beech-magnolia type (see Chapter 5.2.5 for a description). b. Fauna. The aerated. cool (65-70F) clear spring water of steepheads flows over sandy-gravelly substrates from the point on the valley sidewall where ground water seeps laterally. Many of these streams originate from an amphitheatre-shaped valley head where spring sapping takes place along a 270" arc. Water in some Panhandle steepheads has so much volume that fishes such as the creek chub (Semotilus atromaculatus), mosquitofish (Gambusia affinis), and darters (Etheostoma spp.) can be seen within 35 m of the spring source. Steephead streams flowing into western Choctawhatchee Bay from Eglin Air Force Base contain the entire distribution of the federally endangered Okaloosa darter (Etheostoma okaloosae). All across the Panhandle in first-order streams, Means (1974a,b) discovered aspecific suite of plethodontid salamanders that are not found in any other habitats. The larva of these three species live in benthic habitats in ravine streamsfrom 6 months in the case of the central and Apalachicola dusky salamanders (Desmognathus fuscus conanti. D. n. sp.) to 3 years in the case of the two-lined salamander and the red salamander (Eurycea bislineata. Pseudotriton ruberj. Among the many crayfishes that inhabit Panhandle ravine streams, species of Procambarusand Cambarus are the diet of the queen snake (Regina septemvinata), a crayfish-eating specialist that is mammals or birds that use aquatic habitats as their homes, but the opossum (Didelphis virginiana) and raccoon (Procyon lotof) are common visitors. The raccoon, adroit fisherthat it is, possibly has the most impact on the system. Raccoon tracks in the wet sands and organic soils adjacent to ravine streams attest to their presence. 6.3.2 Alluvlal Streams and Rivers Four Panhandle streams are noteworthy for their alluvial character. They are the Escambia. Choctawhatchee, Apalachicola, and Ochlockonee Rivers. All four have blackwater tributary streams, and the Choctawhatchee and Apalachicola have substantial inputs from spring-run tributaries. The alluvial character of these rivers derives from the fact that the greatest portions of their streamcatchments are north of the Florida boundary in clastic-dominated sediments of the Coastal Plain or, in the case of the Apalachicola River, in the southern Appalachian Mountains. Thedevelopment of rooted aquaticvegetation in the riversofthe Panhandle is limited by the influence of one or more of fourfactors: (1) current velocity, (2) water depth. (3) turbidity and color, and (4) fluctuating water levels. Factors 1 and 2 tend to be limiting inchannelswherewaterflow anddeptharegreatest. Rainfall runoff, into the larger Panhandle rivers particularly, isusually quite turbid, limiting light penetration. The only suitable areas forthe development of rooted aquatic species are narrow shelves between the floodplain vegetation and the main channel. Where the Panhandle rivers drain sandy swampy lowlands, the water flowing in the turbulent areas has a browncolor. Thewater in these streams is frequently high in organic acids, tannins, and lignins leached from the decomposing plant litter, giving the water the look of tea. Many Panhandle rivers and streams cut steepsided ravines beneath
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6. Freshwater Habltets the closed canopies of their mature floodplain torests. Light penetration is limited first by the forest canopy, second by the dark color. Also, the steep sidesof streamchannelsgenerally insure that water depth fluctuates widely in response to rainfall and runoft, creating an unstable background environment, especially for submergent plants. These conditions act togetherto limit thegrowth of submergent, emergent, and floating aquatic vegetation. In contrast, the Panhandle rivers and their tributaries suppotl a rich and varied assemblage of aquatic animals (Means 1977. Yerger 1977, Swift et al. 1977). This situation underscores the close interdependence between the streams and their floodplains. Detritus from upland runoff and leaf fall appears to be the major energy source for the Panhandle rivers as well as for thew estuaries. The highly diverse animal community appears to resutl from the diversity provided by bank vegetation and regularly flooded swamp forests rather than by instream plant communities. a. Flora. The aquatic habitats of the alluvial streams of Panhandle Florida can be classified by the water column and by different types of substrates. In the water column, the free-swimming aquatic organisms are plankton (microscopic plants and animals) and nekton (macroscopic motile organisms suchascrayfish andtwefish). Benthicsubstrates are masses of attached algae, compact clay, sand, mud, fixed organic debris (submerged brush, logs, roots, leaf packs), and rock and gravel (Gold et al. 1954). Because alluvial rivers are turbidwith fine suspended sediments, and because river waters continually move and fluctuate in volume, phytoplankton levels often are quite low in this type of coastal plain aquatic habitat compared to those in standing water (Patrick et al. 1967). Wharton (1977) lamented that "general descriptions of Coastal Plain streams are rare.. .I could find few studies of submerged, floating, or emergent higher plants in Georgia rivers." While scientists are beginning to generate considerable knowledge about the ecology of Panhandle estuaries (see Chapter 7), few detailed studies are available on Most algae are common in summer and fall, others in the spring, and afew in winter. Afew green algae (Oedogoniumspp.), red algae (Compsopogon spp., Batrachospermum spp.), and filamentous diatoms form long streamers in faster water. Some blue-green algae (Lyngbyaspp.) form long filaments in still water. The green algae Vaucheria and Oedogoniumform algal mats on sand or mud in shallow water, while Spirogyra exists a little deeper. b. Fauna. The animal life of large Panhandle alluvial rivers isextensive and more well known than the plants. Each river system across the Panhandle has acore of wide-ranging species shared by all the rivers, but each system also possesses many species of invertebrates and fish not found in the other nvers The Escambla Rlver, farthest west of the alluv~al streams, IS most abundantly endowed w~th the anlmal l~fe tvolcal of the western Gulf of Mex~co streams such as the Mlsslss~pp~ R~ver The Escamb~a has ~ts headwaters In the upper Coastal Plaln of southern Alabama. adlacent to the much larger Alabama-Tomblgbee dralnage on lts west The Ochlockonee Rlver, by contrast, recelves a laroe share of ~ts sDecles from the Atlantlc Coastal plain. This may bea result of a shared drainage dlvide with the Withlacoochee River (atributary of the Suwannee River) as well as a possible connection with the Suwannee on the exposed Continental Shelf during the Pleistocene. The Apalachicola River is distinctive because it is the only Florida drainage whose headwaters originate outside the Coastal Plain in the southern Appalachian Mountains. The wide variety of animal life in alluvial rivers is related to the diversity of the physical environments of these streams. For instance, the 68 species of freshwater fishes in the Ochlockonee River (Swift et al. 1977) are distributed among diverse habitats: shallow swift water and slow deep pools, sandy riffles and organic muck, under cut banks and in midstream, ravine tributaries and main channels. A severe change takes place in these streams annually that affects much of the wildlife Runoff of rainwaterfallingonthecatchmentsduringwinterand Panhandle rivers. Information on the ecology of the spring tends to be greater than at any other time of Savannah River in Georgia may not be strictly applithe year (Foose 1983, Means 1986), causing water cable to Panhandle rivers, but afewgeneralities may to spill out of the low water channel into extensive be extrapolated. floodplains. Many riverinespecies suchascatf~shes 163
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Panhandle Ecologlc ial Characterlzatlon (Ictalurus spp.), centrarchids, bowfin (Amia calva), gars (Lepisosteus spp.), and minnows (Notropis spp.) benefit by roving into the expanded aquatic environmentduringthe 1-5 monthsthat annual high waters stand in the floodplain. In addition, species that live in the backwaters of floodplains benefit by the high annual rises which rejuvenate the backwater aquatic systems by providing them with nutrients and water. During winter and spring high water periods, for instance, some species of riverine amphibians breed in the floodplain and spend their lama1 life in the receding waters outside the main lowwater channel. These are the upland chorus frog (Pseudacris triseriata), Fowler's toad (Bufo woodhousiifowler!), and southem leopard frog (Rana sphenocephala). Others breed in the same floodplain backwaters during the summer. Among these are the river swamp frog (Rana heckschero, bronze frog (Rana clamitans), bird-voiced tree frog (Hylaavivoca), gray tree frog (Hyla chrysoscelis), green tree frog (Hyla cinerea), southern dusky salamander (Desmognathus auriculatus), mud salamander (Pseudotriton montanus), long-tailed salamander (Eurycea longicauda), and dwarl four-toed salamander (Eurycea quadridigitata). Alluvial rivers of the Panhandle, while not possessing a great deal of primaty productivity in the water column for filter feeding animals, compensate by being rich in nutrients supplied by litter that washes into the system from floodplain forests and from tributaty streams. Thus alluvial rivers are replete with benthic organisms that attack the litter and, in turn, feed a robust food webof higherfeeding levels. Among the many important invertebrate groups are caddisflies (Wiggins 1977), mayflies (Berner 1950). crayfish (Hobbs 1942), freshwater snails (Thompson 1984), bivalves (Clench and Turner 1956), stoneflles (Stark and Gaufin 1979). and carnivorous groups such as dragonflies (Eyers 1930) and water beetles (Young 1954). The invertebrates are the food base, in turn, for a wealth of fish species. Some fish groups feed on the bottom, such as the sturgeons (Acipenserspp.), suckers (Catostomus, Minytrema, Erimyzon), darters (Etheostoma and Percina), and catfishes (Ictalurus, Noturus). Some feed at or near the water's surface, such as many species of the Cyprinodontidae, Poeciliidae, and Centrarchidae, and others feed in the water column, such as species of those families lust mentloned plus tne gars, bowfin, pickerels (Esox spp.), minnows, shad (Dorosoma and Alosa), and others. Alluvial rivers supportagreatweatlhof reptile life beginning with large numbers of many species of turtles. The world's largest freshwater turtle, the alligator snapping turtle (Macroclemys temmincki!), is largely confined to the deep waters of alluvial streams, and Panhandle Florida rivers are one of the important holdouts of their populations. The Mississippi River and other western Gulf of Mexico drainages have had severe fishing pressure brought to bear on the alligator snapper for use in commercial production of turtle soup. Common omnivores in alluvial rivers are the large river cooters and sliders, most notably the Suwannee and Mobile cooters (Pseudemys concinna sspp.), the peninsula cooler (P. floridana), and the yellowbelly slider (P. scripts). Other important turtles are species of map turtles (Graptemys spp.) found exclusively in large rivers, including a species endemic to the Apalachicola River system, Barbour's map turtle (G. barbour!), species of musk turtles (Sternotherus odoratus and S. minor), and mud turtles (Kinosternonsubrubrum). Alligators (Alligator mississippiensis) are very common in the large alluvial rivers where they have notbeen harassedorkilledout. They eat mostly fish, but turtles are next in importance. While no lizard is specialized for aquatic life in Florida Panhandle rivers, several snakes are. The most abundant snake seen along overhanging branches and along the banks of alluvial rivers is the bmwn water snake (Nerodia taxispilofa) usually mistaken forthe cottonmouth (Agkistmdonpiscivorus). The latter rarely is found in the main channel of alluvial streams, but it flourishes in the backwater slough and swamps in the floodplain. The red-bellied watersnake (Nemd~a eryihrogaster) is also a common riverine species, often seen atthe water's edge where it feedson fish. Otter (Lutra canadensis) and beaver (Castor canadensis) are the only truly aquatic mammals sometimes seen in the main channel of alluvial rivers, but both are more common in the tributaty streams and backwaters. Historically, the manatee (Trichechus manatus) apparently made forays up
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6. Freshwater Habltats into the alluvial rivers of the Panhandle, but this is probably rare or nonexistent today. Alluvial rivers are the feeding grounds for many species of wading and aquatic birds. Wading bird5 such as the great blue heron (Ardea herodias), great egret (Casmerodius alba), and little blue heron (Egretta caerulea) are commonly seen feeding along the banks of alluvial rivers. Diving birds such as the anhinga (Anhinga anhinga), double-crested cormorant (Phalacrocorax auritus), and species of ducks use alluvial rivers extensively. The osprey (Pandion haliaetus) and bald eagle (Haliaeetus leucocephalus) are common raptors that grab fish from the surface of river waters. Although no definitive study of the fauna of alluvial rivers has been done. Means (1977) has surveyed the significance of the Apalachicola River basin to vertebrates, and more information, including a vertebrate species list, is available in the publication. 6.3.3 Blackwater Streams The most widely distributed type of stream in Panhandle Florida we call here the blackwater stream. We combine Beck's (1965) sand-bottomed stream with his swamp-and-bog stream because the latter is merely a slower moving, lower volume version of the former; the swamp-and-bog stream dominated by organic sediments in its bed, grades downstream into a sand-bottomed stream if the drainage system is large enough. The Perdido River, Blackwater River, Shoal River, Titi Creek, Pine Log Creek, Bear Creek, Telogia Creek, New River, and others are examples of blackwater streams that have organic-bottom tributary streams that come together to form the sand-bottomed. blackwater master stream. The highly acid, sluggish swamp-and-bog streams are found throughout Panhandle Florida, and are particularly common in the Gulf Coastal Lowlands (Figure 5). They originate in herb bogs and shrub bogs and show a definite relationship to the sand-bottomed streams in that all chemical differences are functions of velocity (Beck 1965). An increase of gradient would convefl them to the sandbottomed type by increasing turbulence, which in turn Increases reaeratlon, reduces carbon dioxide, increases pH and alkalinity, and removes the finer bottom sediments of organics and silt, replacing them wlh sand. The swamp-and-bog version of blackwater streams has the following characteristics: pH 3.8 to 6.5, alkalinity and hardness both normally well below 40 mgl, color sometimes as high as 750 unls, turbidity low. and carbon dioxide at times above 100 mgll. The velocity of these streams is slow to moderate. The larger volume, sand-bottomed versionofthe blackwaterstream is mildly acidtocircumneutral (pH 5.7-7.4), has alkalinity ranging from 5 to 100 mgl, hardness from 2 to 120 mgl, color moderate to high, and moderate to swift velocity (Beck 1965). a. Flora. Plant life in blackwater streams has not been studied across the Panhandle. While diatoms and algae no doubt make up a considerable portion of the phytoplankton of blackwater streams, the primaiy productivity of blackwater streams is lower than a typical spring-run stream because of the differences in light levels. One emergent that catches the eye in shallow blackwater streams is golden club (Orontium aquaticum), whose green emergent leaves accentuate the golden-tipped spathe rising from dark, sometimes inky, waters. b. Fauna. Blackwater streams support a surpris~ng fish and amphibian fauna, with many species present that are normally considered sensitive to highcarbondioxide values, e.g., sunfishes (Lepomis spp.) and darters (Etheostoma spp.), waterdogs (Necturus spp.), and plethodontid salamanders. According to Beck (1965), the invenebrate fauna of the organic-bottomed blackwater streams differs little from acid ponds. Running water forms and species that thrive in running water are universally lacking. Mollusks are represented only by Physa pumilia, and the general fauna give the impressionof being composed almosttotallyof species highly resistant to organic pollution, even though the streams are not polluted by anthropogenic sources. Typical elements are hydropsychid and philopotamid caddisflies, mayflies of the genera Stenonema and Isonychia, simuliid larvae, Plecoptera, orthocladiine chironomids, elmid beetles, and Corydaliscornutus (Beck 1965). The fishes are an exception.
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Panhandle Ecological Characterization Farther downstream in sand-bottom reaches of the First, spring waters are usually clear because they catchment, flowing water species dominate. have been filtered through limestones. Second, The floodplains of blackwater streams, panicularly where there is seepage, are the breeding sites of several salamanders found more commonly in blackwater streams than anywhere else. These are the long-tailed salamander (Eurycea longicauda guttolineata), southern dusky salamander (Desmognathus auriculatus), and mud salamander (Pseudotriton montanus). Other salamanders living in the water column as adults are the two-toed amphiuma (Amphiuma means), lesser siren (Siren intermedia), and the gulf coast waterdog (Necturus beyer~). Common reptiles of blackwater streams are the alligator (Aligator mississippiensis), common snapping turtle (Chelydra serpentina), peninsula cooter (Pseudemys floridana), stinkpot (Sternotherus odoratus), mud turtle (Kinosternon subrubrum), glossy water snake (Regina rigida), banded water snake (Nerodia fasciata), and cononmouth (Agkistrodon piscivorus) Wading and diving birds tend to use blackwater streams infrequently for two possible reasons: less food may be available because of the reduced productivity or visibility in black water, and the danger from subsurface attack from alligators and other aquatic predators isgreaterthan inalluvial rivers and spring-nrn streams. No aquatic or semiaquatic mammals are known exclusively from blackwater streams, but the raccoon, beaver, and otter use blackwater streams extensively. 6.3.4 Spring-fed Streams Panhandle Florida is not so well endowed with large springs as is central Florida and the Florida Big Bend region, but Rosenau et al. (1977) mapped 37 different springs in Panhandle Florida ranging in discharge from under 5 ft3/s to more than 250 ftYs. Panhandle Florida hasonly two first order magnitude springs (having adischargeof more than 64.6 million gallons per day), Gainer Springs in Bay County and Blue Springs in Jackson County (Fernald and Patton 1984). Most of the Panhandle springs average in the range of 15-35 f13/s. Spring-fed streams are very different from other Panhandle stream types in several important ways. spring-fed streams have relatively constant temperatures at their spring-heads, that persist to a diminishing extent downstream, making them somewhat thermally buffered. Third, they are chemically different from other rivers because they issue from carbonateterranes (limestone sediments) wherethe waters have picked up ions of calcium, magnesium, iron and other minerals. Spring-fed rivers and streams are notably less acidic than other rivers because of their high mineral ion content and seem to be heavily populated with mollusks, possibly because of the high levelsof availablecalcium in the water. Only two major streams of the Panhandlecan be classed as spring-run streams, but both are also heavily influenced by inputs from blackwater stream tributaries. The Chipola River of Jackson, Calhoun, and Gulf Counties receives a large percentage of its flow from springs discharging the Floridan Aquifer from limestones in the southern Marianna Lowlands physiographic region. Many springs discharge directly into the floodplain of the Chipola River north of Marianna, but other springs have outlets into smaller spring-run streamcourses that jointhe Chipola, such as Blue Springs Run. The Floridan Aquifer also discharges into Econfina Creek in Bay County through limestone conduits. A substantial portion of each stream catchment above the zone of the springs receives water as runoff from the surrounding landform, so that immediately below the springs, the waters of both rivers are a blend of calcareous spring waters and acid blackwater stream waters. Holmes and Wright Creeks in Washington and Holmes Counties are also fed by spring waters. During droughts, the waters of Chipola River, Holmes. Wright, and Econfina creeks become clear anddominated by spring-flow. At these times, these streams are more like the classic spring-flow streams of the Big Bend (Wakulla and Wacissa Rivers). During normal rainfall periods, however, all fourstreamscan be sodominated by runoff that their waters are quite dark, and the streams appear superficially as blackwater streams. According to Beck (1965), spring-run streams (called calcareous streams by Beck) typically are alkaline (pH 7.0-8.2), the alkalinity ranging from 20
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6. Freshwater Habitats to 200 rngll, hardness from 25 to 300 mgll, water normally clear, and velocity ranging from slow to swift. The beds of Panhandle spring-run streams consist of sand and limestone in the vicinity of springs, changing to sand, clay, pebbles, mollusk shells (of the introduced clam Corbiculamanilensis), and organic detrlus downstream. a. Stream flora. The clear waters allow much more light to penetrate at depth, and therefore spring-fed streams havethe highest primaryproduction of all Panhandle streams. This is manifest more in macrophytic plants rooted in the subaquatic stream bed than in the water column. Diatoms and filamentous algae also abound but are attached to the physical substrate and the macrophytes. Thermal buffering prevents both low temperatures that slow down plant and animal metabolism and high temperatures that lead to anoxic conditions during summer. Unfortunately, there are no ecological studies of the flora of Panhandle spring-fed streams, so that quantitative information about the mles of different species in primary productivity, and therefore their role as food and coverfor aquaticwildlife, is lacking. b. Stream fauna. Accordingto Beck (1965), the invertebrate fauna of spring-run streams is less current-loving than sand-bottomed blackwater streams. The most obvious benthicfaunalfeature is their high mollusk populations, originally consisting of native genera Goniobasis, Campeloma, VivipaNS, and Pomacea. Today, because of the overwhelming dominance of the introduced clam Corbicula manilensis, the bottom sediments are full of the living and dead shells of this bivalve, to the literal extirpation of many of the native species. Other current-loving invertebrates listed by Beck (1965) are hydropsychid caddisflies, mayflies of the genus Stenonema, a great variety of chironomid midges, Corydaliscornutus, and occasionally Simuliidae and Plecoptera. Spring-wn streams of the Panhandle are noteworthy for their mollusk-eating turtles. Females of Barbour's map turtle (Graptemys barbour!) are several times larger than males, but differ even more in possessing powerful crushing jaws and jaw musculature, enabling them to feed upon the abundant mollusks. A similar adaptation has taken place in the loggerhead musk turtle (Sternotherus minor). Both sexes, however, feed upon mollusks and show enlarged feeding apparatus. Omnivorous turtles are also very common, possibly because llght penetrates deeply in spring-run streams and there is much more aquatic plant productivity than in the other two types of Panhandle streams. Commonly found are the Suwannee Cooter (Pseudemys concinna), peninsula cooter (P. floridana), and sometimes the yellowbelly slider (Pseudemys scripts). The brown water snake (Nerodia taxispilota) is by far the most common aquatic snake encountered in Panhandle spring-run streams, but the red-bellled water snake (N erythrogaster), and the cottonmouth (Agkistrodon piscivorus) are also found regularly, the latter moreoftenoff the main open-water channel in the fringing river swamps. The spectacularly colored rainbow snake (Farancia erytrogramma), specialized to eat freshwatereels (Anguilla rostrata), seems mostly to be found in spring-run streams. Two freshwater fishes are known almost exclusively from spring-fed stream waters in the Panhandle. These are the redeye chub (Notropis harper~) and the bluefin killifish (Lucaniagoode?. Other fishes common to Panhandle spring-run streams include: bowfin (Amia calva), spotted sucker (Minytrema melanops), blacktail redhorse (Moxostoma poecilurum), pugnose minnow (Notropis emiliae), sailfin shiner (N. hypselopterus), coastal shiner (N. petersono, blacktail shiner (N. venustus), longnose shiner (N. longirostris), weed shiner (N. texanus), silverjaw minnow (Ericymba buccata), bigeye chub (Hybopsis amblops), speckled madtom (Noturus leptacanthus), tadpole madtom (N. gyrinus), golden shiner (Notemigonus chrysoleucas), mosquitofish (Gambusiaaffinis), least killifish (Heterandria formosa), blackbanded darter (Percina nigrofasciata), spotted sunfish (Lepomis punctatus), bluegill (L. macrochirus), spotted bass (Micropterus punctulatus), largemouth bass (M. salmoides), brook silversides (Labidesthes sicculus), and others. 6.4 Native Lacustrine Habitats The Panhandle has less water-bearing limestone near the surface of the ground than the rest of
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Panhandle Ecological Characterlzatlon the State, so lakes formed by solution subsidence of the ground surface to levels below the piezometric surface of ground water are less common. Most of these lakes are in northern Bay and southem Washington Counties. Lake Wimico may represent a depression in a relict sea bottom. The second most common type of lake is formed by the natural meandering processes of Panhandle streams and rivers, and we will call them floodplain lakes. The two largest lakes of the Panhandle (Lakes Seminole and Talquin) are impoundments of the Apalachicola and Ochlockonee rivers, respectively. The three largest natural lakes, Dead Lake, Ocheesee Pond and Lake Wimico, are associated in one way or another with the Apalachicola River. The karst lakes of the Panhandle seem to fit the FNAl Sandhill Upland Lakecategory betterthan their Sinkhole Lake type. These generally are rounded solution depressions in deep sandy uplands, usually without surface inflows or outflows. A few lakes on both sides of Econfina Creek in Bay County, however, have or had a steephead stream develop from their margins at the time the sink lake depression formed. In one case, asteephead stream flows over more than a mile into a sinkhole lake The sand resulting from erosion of the steephead valley partially fills these lakes. They typically have a sandy substrate with organic accumulations near their deeper portions. They are characteristically clear, circumneutral to slightly acidic, and moderately free of minerals. Lakes are not very long lived geological phenomena because they receive sediment.la,jen water a. Flora. ~ittle researchon panhandle lakes has from the surrounding uplands, and eventually are been Published. The karst lakes in Bay and Washfilled in The fillino orocess invnlves both inoroanic ington Counties are known to have several interest. . . . . . . . . . . . . . . . = -. . sediments that are washed in bv streams and other ing plants, and a systematic investigation may dissurface runoff and oraanlc sedihents that accumuwier more. Smooth-barked St Johnswort (Hyperrlate from the incomplete decomposition of plant matter. Organic lake sediments are derived mostly from primary productivity in the lake itself and to a lesser degree from imported litter. Young, recently formed Florida lakes usually are relatively deep, sand-bottomed, and possess open surface waters. Later in the filling cycle these lakes become shallow, withdeeporganic sediments in their beds. and begin to support a highly productive macrophyte community of emergent aquatlc grasses, forbs, shwbs, and trees. We classify young, deep, sand-bottomed lakes as karst lakes and the shallow, peat-dominated lakes as swamp lakes. The latter usually are simply late successional stages of the former. 6.4.1 Karst Lakes Panhandle Florida has fewer natural lakes than the adjacent Florida Big Bend region or peninsular Florida, but where lakes are found in the Panhandle. they usually have a limestone solution origin similar to those in the peninsula. Most of the natural lakes in the Panhandle are located in Bay and Washington Counties on the sandy uplands called Greenhead Slope between the Choctawhatchee River and Econfina Creek (Pun and Vernon 1964). These lakes and a few others such as De Funiak Springs Lake, Lake Mystic, Camel Pond, Wright Lake, Moore Lake, and Silver Lake are all of karst origin. cum lissophloeus) is an endangered species endemic to Lake Merial and one other sinkhole lake nearby (Ward 1978). One of the Bay County lakes is a known locality of the threatened karst pond xyris (Xyrislongisepala), which is also found in karst lakes in southern Leon County and Walton County (Ward 1978). Otherrareplantsare knownfromthese lakes, and a pine barrens sundew, Drosera, may be disjunct in the bedof Lake Metial and other Bay County lakes; other populations of this species are known only from North Carolina to New Jersey (R. K. Godfrey, Florida State Univ.. Tallahassee; pers. wmm.). The phytoplankton of Panhandle karst lakes has not been described. Many karst lakes have sandy, treeless shores with zones of successional hebaceous vegetation fringing the waterline. Other lakes have a scattering of cypress around their margins. b. Fauna. Almost nothing is known about the fauna of Panhandle karst lakes Plankton, benthic algae, and submerged aquatic plants are the basisof the food web, which consists of turtles (Pseudemys scripta, P floridana) and invertebrates. Macroscopic predators are fish (centrarchids, topminnows (Fundulus spp.), poeciliids, catfishes (Ictalurvs spp.), bowfin (Amia calva), two-toed amphiuma
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6. Freshwater Habltats (Amphiuma means), bullfrog (Rana catesbeiana), bronze frog (R. clamitans), southern leopard frog (R. sphenocephala), pig frog (R. grylio), snapping turtle (Chelydra sepentina), mud turtle (Kinosternon subrubrum), green watersnake (Nerodiacyclopion), mud snake ( Farancia abacura), black swamp snake (Seminatrixpygaea), and alligator (Alligator mississippiensis). 6.4.2 River Floodplain Lakes The low water channels of rivers migrate over their floodplains through the centuries in wandering loops. These loops eventually are cut off during high waterby newly erodedchannels,formingthefamiliar oxbow lakes that are dammed up at both ends by levees thrown up by subsequent high water stands. Thereafter, following each high rise of the river, the fine particles settle out of the turbid waters that refill theoxbow lake. Overtime, oxbow lakesfill inwithsilt and clay. a. Flora. At first, a newly cut off oxbow lake is only a portion of the river with standing, rather than flowing water in its channel. As the oxbow lake fills in, floodplain vegetation grows in from its sides, eventually closing the open water channel with a canopy of baldcypress ( Taxodium distichum), and gum trees (Nyssa aquatica. N. ogeche). b. Fauna. While the lotic riverchannel and lentic oxbow lake faunas may differsomewhat because of differences in current, Panhandle Florida oxbow lakes have not been intensively studied and compared. The species of aquaticvertebrates in oxbow lakes is a subset of those of deeper, slowerwaters in the main river channel, including the bowfin (Amia calva), alligator, spotted, and longnose gars (Lepisosteus spatula, L. oculatus, L. osseus), chain pickerel (Esox niger), suckers (Moxostoma spp.), catfishes (Ictalurus spp.), pirate perch (Aphredodems sayanus), flier (Centrarchus macropterus). largemouth bass (Micropterus salmoides), warmouth (Lepomisgulosus), bluegill (L. macrochirus), dollar sunfish (L. marginatus), black crappie (Pomoxis nigromaculatus), siren (Siren lacertina), twotoed amphiuma (Amphiuma means), larvae of the riverswampfrog (Rana heckscher~), alligator (Ailigator mississippiensis), alligator snapping turtle (Macroclemys temmincki!), Florida softshell tURle ( Trionyx ferox), river cooter (Pseudemys concinna), peninsula cooter (P. floridana), and yellowbelly slider (Pseudemys scripta). 6.4.3 Swamp Lakes Large swamp lakes such as Lakes Miccosukee, lamonia, and Tsala Apopka of the Florida Big Bend are rare in the Florida Panhandle. Most of the Panhandle lakes are relatively deep limestone solution iakes that have not yet reached an advanced stage of filling in with sediments. There are, however, a number of small swamp lakes in Holmes and northem Walton Counties that appear to be nearly filled in solution basins. In addition,two large lakesin the middle stages of filling in and becoming swamps are of river origin and are not solution basins. Dead Lake on the lower Chipola River is an interesting example of a small river (Chipola) that is naturally impounded by the alluvial sediments of a larger river (Apalachicola) at the confluence of the two rivers. The waters of the Chipola have been backed up long enough for the lake margin to have accumulated massive organic deposas that ultimately will fill in at least the backswamps in time. Ocheesee pond is an even better exampleof a swampcreated bythefilling in of a lake. This wetland lies in an abandoned bed of the Apalachicola River, and the lake basin may later have been enlarged partially by downward and lateral solution of limestone. There is virtually no scientific literature on the biota of the swamp lakes of Panhandle Florida, and we have no insights as to how Ocheesee Pond and Dead Lake differ from river floodplain lakes. 6.4.4 Ponds Panhandle Florida possesses hundredsof small (less than 1 acre) ponds scattered throughout all the physiographic provinces. These water bodies collectively deserve mention as a major lotic type because they are the breeding sites of so many animals. No comparative studies of these ponds have ever been made for the eastern United States so far as we are able to determine, even though these pondsare knowntofield biologistsastheonly places to find certain invertebrates and vertebrates in larval and even adult stages. We are also unable to subclassify ponds into natural groups, but we do recognize that there are major physical differences in thew properties. Some
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Panhandle Eeologil cal Charaderlzatlon are deep woods ponds formed in the hardwood forests of bottomlands that are not inundated by annual high rises of a large stream. Some are flatwoods ponds, and these may be marshy with no trees, or only a thin scattering of cypress or gum, or both. Some are just depressions in sandy flatwoods, with sandy bottoms that grass overduring dry spells, and some have organic sediments perched on sand. Thewatercycleof mostof these ponds isephemeral, but some are permanent or nearly so. a. Flora. The truly ephemeral ponds sometimes have very little distinctive flora except diatoms and other one-celled algae in the water column when water is present. Sometimes these temporary ponds form in depressions in wiregrass flatwoods or in low places insandhills where littledifference is notable in the groundcover between the rare times when the site is wet and when it is dry. As the hydroperiod increases, plant response increases, and often a low swale is evident by its herbaceous distinctiveness, indicating the beginnings of a true wetland. Certain grasses and many sedges seem to be the first indication that the hydroperiod is longer on some sites than on others. All degrees of plant response, depending upon hydroperiod, are evident among the many Panhandle ponds, including those with cypress (Taxodium) and gum (Nyssa)fringingthem. In those ponds with a longer hydroperiod, organic sediments build up, and are obvious underfoot duringdrought periods. A study of small ponds and their physical and biological characteristics would begin to provide an understanding of an important, and often overlooked, habitat type. b. Fauna. A great many unusual species of invertebrates and vertebrates use ephemeral ponds to complete their life cycles. A major reason may be the absence of fish predators. Several rarely seen crustacean groups become dense in these ponds after rains, including the fairy shrlmps (Anostraca) and clam shrimps (Conchostraca). Other crustaceans that bloom in ephemeral ponds are species of isopods, amphipods, anddecapods, including grass shrimps (Penaeidae) and crayfishes (Procambarns). The invertebrate life and algae form a rich food resource and a number of amphibian vertebrate carnivores have evolved to take advantage of it. Ephemeral ponds are often the only places larvae of ambystomatid salamanders can be found. Panhandle Florida has four: the marbled salamander (Ambystoma opacum) is found in ephemeral ponds in hardwood bottomlands, breeding in river floodplain temporary standing water bodies or temporary ponds in low lying woodlands along smaller stream courses; the flatwoods salamander (A. cingulatum) uses temporary ponds in flatwoods, usually temporary cypress or cypress-gum ponds; the tiger salamander (A. tigrinum) also breeds in flatwoods ponds, especially deeper ones with slightly longer water cycles, including ponds with fish; and the mole salamander (A. talpoideum) which has a catholic preference, using almost any temporary pond, in any major terrestrial habitat. Another group of salamanders that depend upon ephemeral ponds fortheir lalval life is the Salamandridae, or newts. Notophthalmus viridescens commonly breeds in ponds and the larvae spendone or more years of their life in the ponds. Newts metamorphose into terrestrial salamanders called efts, and migrate away from ponds to take up a fossorial life in adjacent woodlands of various types. Later, when the breeding urge comes upon them, they migrate backto ponds and undergo another seriesof morphological changes that assist them with aquatic lile. Both newts and the mole salamander mentioned above have the unique life history strategy of retaining their larval morphology (process of neoteny) until sexually mature and breeding if water levels remain substantial for one or more years. If water levels recede or the pond dries up, however, they quickly metamorphose and wander off to live on land until water returns and they are able to migrate back to the pond and breed. Temporary ponds of the Panhandle are quite important to frogs and a couple of turtles. The chicken turtle (Deirochelys reticularia) is known almost exclusively from small ponds. It and the mud turtle (Kinosternon subrubrum) are among the most common turtles seen crossing roads. The ability to disperse from one drying pondto another is certainly an important adaptation found in animals that live in drying ponds. But frogs, among the vertebrates, seem to use temporary ponds the most, posslbly becauseofthe absenceof predaceousfishes. Frogs
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6. Freshwal rely on temporary ponds so much that several speciesin Panhandle ponds even breed only duringcold weather in the middle of the winter. The spring peeper (Hyla crucifer), ornate chorus frog (Pseudacris ornata), and Florida chorus frog (P, nigrita) use these pondsfrom Novemberto February when there is ample winter rain. A definite spring breeding burst occurs in these ponds from February-April during very heavy rains, when the southern toad (Bufo terrestris), gopher frog (Rana areolata), and southern leopard frog (R. sphenocephala) breed, sometimes with huge numbers of the spadefoot (Scaphiopus holbrookii). But it is the summer rains that bring out the largest number of breeding species. Beginning in May and continuing until September, ponds in the Panhandle are teeming with breeding activity and tadpoles. The following are species of frogs that mostly depend upon small ephemeral summer ponds for the larval portion of their life cycle: oak toad (Bufo quercicus), narrowmouth toad (Gastrophryne carolinensis), pinewoods tree frog (Hyla femoralis), barking tree frog (H. gratiosa), squirreltreefrog (H. squirella), little grass frog (Limnaoedus ocularis), cricket frog (Acris gryllus). Otherfrogspecieswhichare morecatholicin the selection of their breeding habitats such as the green tree frog and gray tree frog (H. cinerea, H. chrysoscelis), also breed in these ponds. When fish are found in ephemeral ponds, they almost always include the following: pygmy sunfishes (Elassoma spp.), pirate perch (Aphredoderus sayanus), mosquitofish (Gambusia affinis), and often the banded topminnow (Fundulus cingulatus). NO aquatic mammals are known to use ponds exclusively, but opportunistic predators such as raccoon and opossum are common, especially when water levels begin to go down and the large numbers of larvae are concentrated. These ponds support one of Florida's endangered birds, the wood stork (Mycteria americana), which feeds on small fish and amphibian larvae whenpondsare drying up. The fact that so many animals are found only in ponds, or have special adaptations for pond life. indicates that the pond is a very important true habitattype, and not an atiiactof human attempts to define nature. Studies on Panhandle ponds are urgently needed. 6.4.5 Coastal Ponds Between sets of aeolian dunes or wave-created sandy berms along the coastal barrier islands and the mainland lie interdune depressions, or flats. Mten these depressions have water standing in them for periods ranging from a few days to nearly always. The FNAl designation for these water bodies is Coastal Dune Lake. These ponds are very important to the wildlife of coastal strands, and we single them out here for recognition. The bottoms of coastal ponds are predominantly composed of sand, with some organic matter. The amount of organic matter depends upon hydroperiod-short hydroperiods allowfasterdecomposition of organic sediments, so that some interdune flats that have water standing for only a few days to weeks after rains have almost no organic sediments at all. The salinity of coastal ponds is variable and subjecl to Saltwater intrusion from beneath during drought, from storm surges, and from salt spray transported by the wind. Coastal ponds are slightly acidic, but onen have hard waters with high mineral content (especially sodium chloride). Coastal ponds, occurring at the continental margin and on barrier islands, are very young geologically. Those on Panhandle barrier islands such as St. George. St. Vincent, and Dog islands are no more than 6,000 years old. Because the barrier island ponds have formed in isolation from the mainland, each pond is likely to have its own distinctive subset of wail plants and animals in it On St. Vincent Island, for instance, almost no titis (Cyrillaceae) fringe the coastal ponds in the manner that they do on the mainland. Instead, the evergreen shrubs in many St. George Island ponds are replaced with persimmon, Diospyros virg~niana. No studles are available comparing coastal pond biota. Many species typical of ephemeral water bodies can be expected in coastal ponds, partly because of the dearth offishinthem. Ostracods, amphipods, anostracans, conchostracans, and isopods should be looked for after rains. Afew frogs and toads use coastal ponds, including the southern toad (Bufo terrestris), southern leopard frog (Ranasphenocephala), and pig frog (Ranagrylio). The first fish to appear inthese ponds
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ranhandle Ecologlcal Characterlzatlon usually are the mosquitofish (Gambusia affinis), but some larger, permanent ponds on St. Vincent Island contain the spotted gar (Lepisosteus osseus), bowfin (Amia calva), lake chubsucker (Erimyzon sucetta), brown bullhead (Ictalurus nebulosus), golden topminnow (Fundulus chrysotus), pygmy killifish (Leptolucania ommata), least killifish (Heterandria formosa), sailfin molly (Poecilia latipinna), tidewater silverside (Menidia beryllina), everglades pygmy sunfish (Elassoma evergladef), warmouth (Lepomisgulosus), bluegill (L. macrochirus), redear sunfish (L. microlophus), largemouth bass (Micropterus salmoides), striped mullet (Mugil cephalus). and the fat sleeper (Dormifator maculatus) (Christman 1984). Coastal ponds are very important to wildlife, especially on barrier islands, because usually they provide the onlywateravailable. Forthis reasonthey are extremely important to incoming migrant birds that are returning from cross-Gulf migration. 6.5 Subterranean Habitats 6.5.1 Water-filled Caves Beginning with Lonnberg (1894a, 1894b), studies of the animal lifeof cavesand sinkholesin Florida and adjacent parts of the Coastal Plain of Georgia and Alabama have revealed a number of caveadaptedorganismsthat areendemic inthe Apalachicola River drainage basin. Because Panhandle Florida solution cavities are presently filled with water, the number of aquatic troglobites (phreatobites) is large in contrast with the number of troglobites (cave-adapted animals) in air-filled cave ecosystems of the Appalachian region of the eastern United States. Means (1977) recognizedthreegroupsoftroglobites In Florida and Georg~a bythe follow~ng names: the Chattahoochee fauna, named for the anticline which brought limestone terranes to the surface in the Marianna Lowlands-Dougherly Plain physiographic region (same as Pylka and Warren's (1958) northern regi0n);the Woodville fauna, namedforthe Woodvllle Karst Pla~n of the Gulf Coastal Lowlands physiographic region (Hendfy and Sproul, 1966); and the Ocala fauna, named for the Ocala Uplift in peninsular Florida. These last two areas plus sinkholes breaching the Hawthorne Formation along the Peninsular Arch. In Panhandle Florida only one fauna, the Chattahoochee fauna, is present. At least eight caves in the Marianna Lowlands-Doughetty Plains region share the Chattahoochee fauna (Figure 68). A number of springs and subterranean water-filled passages which probably contain the Chattahoochee fauna are located along the west bank of the Apalachlcola River for several miles south of Sneads. The nature of the barrier isolating the Chattahoochee fauna from other troglobites is now benerknown becauseof geological and hydrological studies carried out in the past decade (Figure 69). A faulted syncline complementary to the Chattahoochee anticline is present between the Apalachlcola and Ochlockonee Rivers, and contains clastic sediments of low permeability (Veatch and Stephenson 1911. Applin and Applin 1944, Herrick and Vorhis 1963. Sever 1964, Kaufman et al. 1969). Also, limestone underlying the clastic sediments in the trough does not show evidenceof significant solution or secondary permeability (Hendry and Sproul 1966). This geomorphicfeature has been called the Gulf Trough (Hendfy and Sproul1966). The eastern edge of the Gulf Trough contains another structure, the Ochlockoneefault (Kaufman et al. 1969), which may also serve as an impediment to hydrologic flow to the southeast (Figure 69). Recent studies of disequilibrium patterns of naturally occurring uranium isotopes demonstrate that "...the Gulf Trough and Ochlockonee Fauit act as a hydrologic barrier that prevents any significant southeastward flow of groundwater (Kaufman et aL 1969, p. 384). Much of what is known about phreatobles of the eastern gulf region came from studying specimens brought upfromwells which penetrate cavities in the Floridan aquifer (Carr 1939; Hobbs 1942, 1971; Hobbs and Means 1972). In many cases, the nearest entrance to the aquifer is through sinkholes or springs several miles fromthe well. AAerCarr (1939) described the Georgia blind salamander (Haideotriton wailaceicarr) from a deep well in Albany, Georgia, specimens were discovered incaves in Jackson County, Florida (Pylkaand Warren 1958). Alltroglobitic salamanders presently known from this karst region are Haideotriton wallacei.
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Panhandle Ecological Characterization 100Shows lh~ckness of Pl~ocene, ISOPACH Plelslocene or~d Holocene depos~ts combined ; Interval 50 feet. Karst topoqrophy Flor~dan aqu~ fer ot or neor lond surface both recharge ond dlschorge occur. Q First Mogn~tude Spr~ng Figure 69. Regional structure of eastern Panhandle Florida showing the Gulf Trough putative barrier to dispersal between the Chattahoochee and Woodville phreatobite faunas. (Kaufman et al. 1969).
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6. Freshwater Habltats Two epigean species (Eurycea bislineata, E. longicauda) are known troglobiies in caves of the Marianna Lowlands and in Climax Cave, Georgia. Larvae of both species have been found in and near the mouths of caves in pools and streams issuing from the underground water system (Means, personal ObSe~ati~n). Both of these species of Euryceaare typically northern animals. It IS not known whether either gave rise to Haideotriton wallacei, but they or their ancestors are the most likely candidates. The species H. wallacei and T. rathbuni of Texas share the distinction of being the most highly cave-adapted salamanders in North America. The endemic crayfish, Cambarus crypfodytes was also described from the specimens obtained from a well; they, too are now known to be abundant in caves in Jackson County. Both Cambarus cryptodytes and Haideotriton wallacei live together in the water column, especially near nutrient inputs such as subterranean streams beneath bat roosts in caves. Gerard's Cave (Pylka and Warren 1958) in Jackson County has several vertical cracks In the cave floor under bat roosts where these species are common year around. Apparently the crayfish forage on detritus from bat excreta and carcasses, and on other aquatic life that feeds on the same fare. Middle-sized and large crayfishes are capable of capturing and feeding upon Haldeotrlton wallacei. The crayfish probably also feed upon some of the food items that have been identified in thediet of the cave salamander, including ostracods, amphipods, isopods, copepods, insects and a species of mite (Lee 1969). The troglobitic isopod, Asellus hobbsiisfound in the MariannaLowlands inthe Panhandle and in cave waters of peninsular Florida. However, its occurrenceincrayfish burrowsin CalhounCounty south of Blountstown (Maloney 1939) and the tendency for other subterranean isopods to occur in epigean waters (Minckley 1961) indicates surface dispersal and would not require continuous limestone connection between the two regions in the study area. Peck (1973) identified an amphipod (Crangonyx floridanus) and a copepod (Macrocyclops albidus) from guts of Haideotriton wallacei. The extensive system of subterranean waters and solution cavities drained by the upper Apalachicola basin contains an isolated and unique ecosystem of cave-adapted aquatic organisms. Major threats to this ecosystem are impactsfrom pollution (municipal waste effluents, siltation, and turbidity due to surface erosion in open recharge areas) and alteration ot the water table (by impounding local streams, including the Apalachicola and Chipola Rivers, or from heavy drawdown by wells). Serious consideration should be given to influences on the local water table. 6.6 Human-Created Lacustrine Habitats People have created numerous lotic environments over Panhandle Florida, mostly of the small, ephemeral type along roadsides and railroad rightsof-way. Roadside ditches are so common that biologists commonly use them for collecting and teaching, yet almost no Studies of the biota of roadside ditches, per se, are available. The closest natural lotic environments to roadside ditch ponds arethe ephemeral pondsdescribed in Chapter6.4.4. Somewhat larger than roadside ditches are the bormw pits created by roadbuilders for road wnstruction. Thesewaterbodies arequite sterile, even more so than roadside ditches, because they usually are deeper. In the Panhandle, particularly the Coastal Lowlands region, borrow pits are characterized by the dense growths of St. Johnswort (Hypericum spp.) that flourish after mechanical disturbance to a wetland. 6.6.1 Impoundments The largest of all human-created lotic environments, however, are the Impoundments of streams and rivers. These are numerous over the entire Panhandle. Many are fish management areas maintained by the Flor~da Game and Fresh Water Fish Commission Some of the smallto medium-sized impoundments are Bear Lake (1 07 acres) in Santa Rosa County, Hurricane Lake (400 acres) in Okaloosa County, Juniper Lake (665 acres) in Walton County, Lake Stone (130 acres) in Escambia County, Lake Victor (134 acres) in Holmes County. Merritt's Mill Pond (202 acres) in Jackson County, and Smith Lake (160 acres) in Washington County. There are surprisingly few impoundments of the larger rivers, however, even when compared to the
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Panhandle Ecological Characterization upstream reaches of these rivers north of the Florida State line. The three largest are Lake Talquin on the Ochlockonee River (4,004 acres), Deer Point Lake (5,000 acres) on Econfina Creek north of Panama City, and Lake Seminole (37,000 acres). The Florida Department of Environmental Regulation recently completed a I-year study of water quality in Panhandle impoundments (FDER 1986d). This investigation includedthe monitoringof benthic macroinvertebrate and periphylon populations upstream of, in, and downstream of 17 Panhandle impoundments. This study found that the nutrient enrichment in the impoundments resulted in oxygen depletion, depauperate populations of benthic macroinvertebrates, and enhanced growth of algae. Not only were there effects within the impoundments, but there were profound adverse effects downstream of the impoundment that resuled in reduced macroinvertebrate populations. The largest lake in Panhandle Florida is Lake Seminole, an artificial impoundment of the Chattahoochee and Flint rivers, backed up behind Jim Woodruff Dam exactly at their point of confluence at the beginning of the Apalachicola River. This large lake, with a surface area of 152 km2 and a total volume of 9,439 kd, is the last of 16 impoundments in thedrainage basin, and the only one on the Florida reaches of the river. a. Flora. Phytoplankton in Lake Seminole are dominated by diatoms (Melosira distans. Asterionellaformosa), whichduring the cooler months make up as much as 77% of the population. During the warmer months, blue-green algae become dominant, making-up 76% of the total numbers. Coincident with this seasonal pattern is a switch in limiting nutrients from phosphorus in the cool months to inorganic nitrogen in the summer and fall. Cell numbers also vary seasonally, averaging lowest in winter months (1,951 cellslml) and highest in Sep tember (14,729 celWml). An average of 37.5 taxa (13 to 51) of phytoplankton were reported from 17 stations in the lake over a 6-month period (USACE 1981). Aquatic macrophyles cover approximately 40% of the sudace area of Lake Seminole and virtually 100' of the area less than 2 m in depth (USACE 1981). Over 700 taxa of macrophytes have been identified, with 73 being reported as common to abundant (Table 14). b. Fauna. We were unable to find comparative studies of the trophic relationships within Panhandle impoundments, although various lakes have been monitored for various periods by the Florida Game and Fresh Water Fish Commission. The fauna of impounded lakes derive mostly from the native faunas of the rivers in question, and partly from lentic water species that find their way into the lake by means of chance dispersal and by human transport. Allof the impoundments in the Panhandle have been stocked with game fishes, mostly bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides), and channel catfish (lctalurus puncfatus), and withother speciesona more limited basis (Gatewood and Hartman 1977). The fish, mammal, and waterfowl recreational values of these impoundments were summarized by Gatewood and Haltmann (1977). Table 14. Aquatlc macrophytes noted to be common to abundant In Lake Semlnole during 1978-79 field surveys by the Army Corps of Engineers (USACE 1982). S = Submersed; E = Emergent; F = Floatlnq. (continued) Algae S E F Chara spp.; chara LyngbyaSpirogyrq algal mat Nltella spp.; nnella Vascular S E F Justicia amencana; water willow Sagittarla latifolia: common arrowhead Akernanthera phibxemides; alligator-weed CoIocasia esculenta: wild taro
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6. Freshwater Habitats Table 14. Continued Vascular (continued) S E F Orontium aquaticum; golden club Alnus serrulata; speckled alder Betula nfgra; river birch Brasenia schreberi, watershield Cabomba caroliniana; fanwort Vascular S E F Myrica cerifera, wax myrtle Najas guadalupensis; southern naiad Najas minor: naiad Nelumbo lutea; American lotus Nuphar luteum, spanerdock Sphenoclea zeyland~ca, ch cken sp~ke I Nymphaea odorata, fragrant waterl, y Ceratophyllum dnmnrsum: common coonta.l. Nyssa aqualtca; swamp t~pelo Ceratophyllum echinatum; prickly coontail / Nyssa ogeche; ogeche tupelo Mzkanla scandens, c Imb ng hempweed Ludw~gla decurrens: s nged water primrose Care* spp sedges 1 Ludw~g~a lizocarpa water pr~mrose Cyperus spp ; sedges Eleocharis ac~cularfs, slender spikerush Eleochar~s cellulosa; spikerush Eleocharsl equsetodes, knoned spikerush Ludwigiapalustris; water purslane Ludwigia peruviana; water primrose Platanus occidentalis; sycamore Polygonom spp.; smartweeds Hydrochloa carol~nens~s, water grass -. I tchhornfa crassfpes, water hyac ntn Leersra hexandra, c,.t.trass Pontederta cordata. p~ckerelweed Panicum hemitomum; maidencane Pontederia lanceolata; southern Panicum repens; torpedograss pickerelweed ~izanio~sis miliaceae; giant cutgrass Hypericum spp.; St Johnsworts snailseed pondweed Mynophyllum brasrl~ense: parrolteatner Potamogeton dbnorens~s, Ill!n~s~ondweed Mynophyllum spicatum, E~ras~an Potamognton nodosus: Amercan ponoweed watermllfoll Egena densa, elodea Hydrflla veri~cfllata hydr~lla Vall~snerra amerlcana, eelgrass Juncus effusus, soft rush Juncus spp rushes Lemnaperpusflla, common duckweed Spfrodela polyrhfza, giant duckweed Utr~culana flor~dana, giant bladderwort Utrfcular~a ~lflata, float~ng bladderwort Utrfculana purpurea, purple bladderwort Mayaca fluv~atfl~s, bog moss Nymphofdes aquat~cum, banana Illy Cephalanthus occidentalis; bunonbush Salix camliniana, coastal plain willow Salix nigra; black willow Saururus cernuus; lizard's tail Bacopa carol~niana; water mint Sparganium americanum; burreed Taxodium ascendens; pond cypress Taxodfum distichom; bald cypress Typha domingensis; southern cattail Typha latifolia; cattail Hydromtyle ranunculoides; splitleaf pennywort Xyris spp.; yellow-eyed grass.
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Chapter 7 ESTUARINE, SALTWATER WETLAND, AND MARINE HABITATS 7.1 Introduction Classification of the saltwater habitats follows the scheme of Cowardin el al. (1979) as closely as possible (Table 15). Two systems, estuarine and marine, make up the saltwater environment. Included within each system are two subsystemssubtidal and intertidal. It is not possible to classify many of the Panhandle habitats as strictly subtidal or intertidal. For example, Oyster reefs are primarily intertidal, but some are entirely intertidal and some may have both interlidal and subtidal regions. Given these problems, most habitats within the two systems are not subdivided further into strict subsystems. Class (henceforth "habitat") definitionsare maintained and are based upon substrate composition (e.g., oyster reef) or primary vegetation (e.g., seagrass bed). In this document, the water column Is treated as a separate habitat--open water--and includes fish and tmly planktonic forms that cannot be assigned to specific habitats. The short and very arbitrary naming and delineation of habitats are made with the following caveats: (I) the environment is a continuum of habitats, each one unique (e.g., not all oyster reefs are exactly the same) and each one dependent to varying degrees upon the others, and (2) many organisms use multiple habitats during different times of the day or different Me stages and, therefore, cannot be assigned precisely to a single habltat. Wherever possible, maior discrepancies in the classification are underscored. A gross-level classification of the fauna is made according to the sizeof the organism, especially the benthos (bottom-dwelling organisms), forwhich size categories have traditionally been based upon retention on various sieve sizes: macrofauna (>0.500 mm), meiofauna(0.500-0.062 mm), and microfauna (<0.062 mm). This scheme has limitations. Some macrofaunal organisms are included as meiofauna early in their development, hence both temporary and permanent meiofauna distinctions are made. Nevertheless, the categories roughly follow taxonomic lines such that the macrofauna generally includes echinoderms, polychaetes, bivalves. oligochaetes, and crustaceans, such as decapods, amphipods, and isopods. The meiofauna includes harpacticoid copepods, nematodes, ostracods, kinorynchs, polychaetes, and gastrotrichs. The micmfauna includes ciliates, fungi, and bacteria. Within this overall organization, there are trophic (i.e., deposit feeders and suspension feeders) and lifeposition (i.e., epifaunal and infaunat) distinctions. The classification of flora is also based roughly on size: macrophytes (e.g., seagrasses and salt marsh grasses) and microphytes (e.g., phytoplankton and benthicdiatoms). The boundaries, however, are less rigidly defined. Given the large area of coast covered in the Panhandle region, it is unrealistic to report every species present or the small, albeit interesting, differences among watersheds. Primarily, dominant and ecologically important organisms are reported. An attempt has been made to highlight general panerns and interactions obsewable throughout the different locates. In addition, the role and natural history of some commercially important organisms are reported. Within each habitat description, assessments and projections were made on potential and realized human impacts. Because they are semienclosed and have limited circulation, coastal estuaries and lagoons are very sensitive to pollution impacts, even though they ordinarily possess much higher nutrient concentrations than the marine or freshwater areas.
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7. Estuarine, Saltwater Wetland, and Marlne Habltata Table 15. Deflnltlon of estuarlne and marlne systems (after Cowardln et al. 1979). Estuarine System Marlne System Consists of deepwater tidal habitats and adjaConsists of the open ocean overlying the Conticenttidalwetlands thataresemienclosedby land but nental Shelf and its associated high-energy coasthave open, partly obstructed, or sporadic access to line. Salinities exceed 30 ppt with little or no dilution the open ocean. It contains ocean water that is at except outside the mouths of estuaries. It includes least occasionally diluted by freshwater runoff from habitats exposed to the waves and currents of the the land. The salinity may periodically increase open ocean. above that of open ocean due to evaporation. Llmlts--extends: (1) upstream and landward to where salinities do not fall below 0.5 ppt during the period of average annual low flow; (2) to an imaginary line closing the mouth of a river, bay, or sound: (3) to the seaward limil of wetland emergents, shrubs, or trees where they are not included in (2). Subsystem* (1) IntertidaCsubstrate exposed and flooded by tides: includes the s~lash zone: 12) subtidal-substrate'continuouslv submeraed. Llmlts--extends from the outer edge of the Continental Shelf shoreward to one of three lines: (1) the landward limit of tidal inundation (extreme high water of spring tides), including the splash zone from breaking waves: (2) the seaward limit of wetland emergents, trees, or shrubs; (3) the seaward limit of the Estuarine System. Subsystem* (1) Intertidal-substrate exposed and flooded by tides; includes the splash zone; Estuaries act as nutrient and pollutant sinks includes those destructive impacts (usually the most through three major mechanisms: (1) sediment easily detected), such as dredging and construction, adsorptiokthe abundant clay-sized sediment parthat result in changes in habitat quantity. The second ticles tend to adsorb nutrients and other chemicals; includes those impacts, such as excessive organic when concentrations in the water column decline, loading, that alter and degrade habitat quality. In sediments release theirnutrients: (2) the basic circuSome instances, lhe In many lation panernof the estuaries--there areusually only cases, specific impact studies on Panhandle sites limaed tidaland windgenerated currents in estuarare lacking and projected effects were derived from ies, and retention times are generally long; (3) biodeOutside the immediate area' positiowlarge numbers of suspension-feeding mollusks (e.g., oysters) and crustaceans remove suspended materials and package them into feces and pseudofeces. These act as large particles that sink to the bottom and are buried; the nutrients and pollutants contained in them may later be released by erosion, sediment reworking by the benthos, and dredging. In this document, human perturbations are generally grouped into two broad classes. The first 7.1.1 Tldes and Sallnity Ranges There are two types of tides along the Panhandle coast: semidiurnal from Ochlockonee Bay to Apalachicola Bay and diurnal (daily) from ApalachicolaBay westward to Perdido Bay. The semid~urnal tides are mixed (i.e., have unequal highs and lows) and range from 0.67 m to 1.16 m (Stout 1984). Diurnal tides have smaller amplitudes, ranging from 0.37 m to 0 52 m. Local daily tidal conditions are highly dependent upon meteorological conditions such as wind SDeed and diredion.
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Panhandle Ecological Characterlzatlon Nearby gulf coastal water salinities are characteristically marine and stable through the year, averaging between 34 and 35 ppt. On the other hand, the bays and estuaries demonstrate fluctuating salinities that depend on a variety of physical factors such as river flow, rainfall, and tidal and wind conditions. The bays, except for St. Joseph and Alligator Harbor, which do not have rivers and streams supplying freshwater inputs, usually have definable haloclines that intensify during heavy rainfalls and dissipate during droughts. The interface between brackish bay water and saline gulf water approaches the surface on incoming tides and falls during outgoing tides. Northerly winds (especially strong in the winter) can cause the surface water of bays10 move gulfward and can lower salinities up to 7 ppt (Salsman and Ciesluk 1978). Bay water salinity is low near river mouthsand ranges between 20 and38 ppt through most of their area. 7.2 Estuarine Habitats 7.2.1 lntroductlon The discussion of the estuarine habitats follows a general format: first, the habitat is introduced with general background information; second, the flora, fauna, or both typically found in the habitat is discussed: third, the distribution of the habitat is provided;fourth, the trophi interactionswithinthe habitat are given; and last, the natural and human impacts are presented. Sections will not be included where information was not available. 7.2.2 Bracklsh Marshes a. lntroductlon. The brackish vegetation habitat includes both emergent and submergent forms. The habitat is primarily limited to salinities in the range of approximately 0 to 15 ppt and is generally located along river mouths subject to tidal influence. b. Vascular species. Clewell (1978) investigated the extensive brackish marshes (i.e., emergent vegetation) at the mouth of the Apalachicola River. The marsheswere primarily dominated by sawgrass (Cladium jamaicense). However, large patches of black needlerush (Juncus roemerianus) interrupted the sawgrass in places, particularly near the river channels and its distributaries. Other herbs were also common within afew meters of the banks of the channels, especially Cicuta maculata, lpomoeasaginata (morning glory), Rumex verticillatus. Saginaria lancifolia (arrowhead), Spartina patens (saltmeadow cordgrass), and Teucrium canadense. These and others are generally incidental or absent in the interior expanse of the sawgrass meadow. The dominant brackish-water submergent vegetation includes three species: Vallisneria ameri. cana, Potamgeton sp., and Ruppia maritima. East Bay in the Apalachicola Bay system has been the most extensively studied (Livingston 1980, 1984). Harper (1910) published the only other account of emergent brackish marshes in the Panhandle (specifically the Apalachicola). Brackish vegetation is perennial, with annual diebacks starting in the fall and continuing at low biomass through the winter. This vegetation probably serves as an important source of detrital material providing energy for the species in the area. c. Associated fauna. McLane (1980) described 33 species of benthic infauna from an area of East Bay (north Apalachicola Bay) brackish vegetation (Table 16). The dominant macrophytes were Vallisneria americana and Ruppia maritima. The six most abundant macrofaunal organisms (indescending rank) were Grandideriella bonneroides (amphipod), Dicrotendipes sp. (insect larva), Laeonereis culveri (polychaete), a nematode, Mediomastus californiensis (polychaete), and Amphicteis gunner; (polychaete). The number of macrofauna ranged from approximately 1,000 to 10,000 individuals/m2. Peak numbers were recorded from September through March. Lowest densities were recorded from May through August. Biomass peaked in February to March and Augustto September. Purcell (1977) described the epibenthic fauna associated with tape weed (Vallisneria americana) beds in East Bay anddiscussed that this habitat is an important nursery area especially for blue crabs (Callinectes sapidus). d. Human Impacts. Timber clear cutting increases ~noff and sediment load in streams leading
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7. Estuarlne. Saltwater Wetland, and Marlne Habkats Table 16. Common benthic macroinvenebrates found In brackish vegetatlon In the Panhandle (McLane 1980). species Specles Crustaceans Cerapus spp. (amphipod) Polychaetes Amphicteisgunneri Corophium lousianum (amphipod) Laeonereis wlveri Gammarus macromucronafus Mediomastus californiensis Grandideriella bonneroides Streblospio benedicti (amphipod) Callinectes sapidus Mollusks Littorina sphictostoma Mactra fragilis into the estuaries. The increased turbidity and sediments and lower pH (i.e., higheracidity) cut down on light for photosynthesis. The increased sedimentation also smothers plants and animals. 7.2.3 Salt (or Tidal) Marshes a. Introduction. Sal marshes are plant communities of the intertidal zone that represent a transition between terrestrial and marine ecosystems. Generally, marshes develop along low-energy coasts under stable or emergent conditions (Chapman 1960). Salt marshes develop in estuaries, behind the shelter of spits, offshore bars, and islands, in protected bays, and along very shallow seas. All these environments provide the marsh with protection from high-energy waves and allow for sediment accumulation and plant community expansion. cases even agricultural crops (Odum et al. 1974). The high productivity isgenerally attributed to a large input of nutrients and particulate organic matter (of freshwater and marine origin), river flow and rainfall fluxes, tidal energy input, and basic physiographic and biological features. Three groups of organisms are responsible for the high productivity: phytoplankton, algae (on sediments and plants), and vascular plants. Both the aboveand below-ground productivity make very important contributions. The detrital food web appears the most important in sail marshes (Odum and de la Cruz 1967). Very few anlmals feed dlrectly upon Spartina or Juncus. Salt marshes perform four major ecological functions: (1 Thev IIroduCe relativelv larae auantiies of Numerous factors influence the areal organic matie; per unit area p& time. some of this salt marshes, The most important of these are: Organic maner is stored in the marsh in the form of peat, some is recycled in the marsh through avariety (1) the relation of land to sea level (i.e., whether of food chains, and some is transported out of the the coastline is stable, emerging or submerging): marsh and dissi,,ated into the estuaries, (2) the composition of the substrate; (3) the amplitude of local tide; (2) They a;e the exclusive habitat of a few species of algae and seed plants, of a large variety (4) winds, currents, and waves-through their of invertebrates, of a large number of birds, and of a effects on sedimentation and aggradation (i.e., detrifew reptiles and mammals. tal loading)-and; (3) They provide substantial protection to adja(5) the nature of the body of water facing the cent low-lying uplands from saltwater intrusion, marsh. coastal erosion, andquantitiesof drifting debris, and, in expansive marshes, from salt spray. The coastal marsh system is highly productive, (4) They are important nursery grounds and exceed~ng natural upland vegetation and in some refuges for commercial and sport species.
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Panhandle Ecologlc; 11 Characterlzatlon Three different plant communities can be delineated within salt marshes (Stout 1984): (1) saline marshes that experience tidal waters of marine salinity; (2) brackish marshes where tidal waters are routinely diluted before flooding of the marsh; and (3) transitional communities between brackish and freshwater marshes (also called "intermediate marshes"). Note: the brackish marshes were discussed in the previous section. Salt marshes are usually characterized by large, homogeneous expanses of dense grasslike plants. Typically, the marshes are dominated by one plant species and named accordingly (e.g.. Juncus marsh). The marsh community is usually low in macrophyte species diversity (see Table 17) with incidental species having a patchy occurrence and represented by only a few species. b. Major physlographic features. Threetypes of surface irregularities occur in Panhandle salt marshes: tidal creeks, natural levees, and barrens. Tidal creeks form when minor irregularities in marsh substrate cause the tidal water to be guided into definite channels (Chapman 1960). Once channels are formed, tides cause further scouring and prevent recolonization by vascularplants. Channels also deepen by accretion on their banks of sediments trapped around the roots of plants bordering the creek. As sedimentation increases and the marshfloorbuilds, creeks may lengthen and branch. Where the surface slope is gradual, creeks are less branched and the main channels are sinuous. The sinuosity of tidal-creek channels facilitates flooding and drainage, and promotes extension of the marsh by reducing the time required for the inward movement of seawaterwith each rising tide. Creek banks often support different vegetation from that immediately beyond the bank. Natural levees develop from sand deposited on upper beaches by very high tides. Most natural levees slowly move landward through the action of tides. Very high tides continually remove sand from the seaward side and redeposit it on the landward side of levees. Barrens (or salt barrens and salt pans) develop during the initial stages of marsh formation because of the irregular colonization patterns of salt marsh 'pioneer" plants, which surround low bare areas and cause them to lose their outlets for tidal waters. These areasfillduringspring tides and holdwaterfor long periodsof time. In summer, evaporationcauses the salinity to rise and plants cannot invade the area. The characteristic round shape of salt pans may result from eddies that form on their borders during flooding. Barrens can also form by deposition of sand and silt in irregularly flooded areas (Kurz 1953, Kurz and Wagner 1957) and from debris tossed up on the marshes by tides and storms that sometime smother the marsh vegetation. In addition, they may Table 17. Common vascular plants (In order of abundance) present In Panhandle salt marshes (Stout 1964). S~ecles Common name Juncus roemerianus Black needlerush Sparfina a/terniilora Smooth cordgrass, oystergrass Spartina patens Saltmeadow hay, saltmeadow cordgrass Spartina cynosuroides Giant cordgrass, rough cordgrass Distichlis spicata Salt grass Scimus ohevi Three-sauare sedae Soecles Common name Scirpus robustus Leafy sedge Salicornia bigelovii Annual glasswort Salicornia virginica Perennial glasswort Batis maritima Saltwon Phragmifes australis Common cane, Roseau cane Baccharis halimifolia Sea myrtle Iva frutescens Marsh elder
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7. Estuarine, Saltwater Wetland, and Marine Habitats form behind a levee as a narrow strip devoid 01 vegetation. Most are temporaly and usually recolonize within a few years, depending on salinity levels and depth of the barren (Kurz 1953). c. Distrlbutlon. The marshes in the Panhandle are developing on the seaward edge of the Pamlico terrace of the late Pleistocene (Kun 1953, Coultas 1980). The Pamli terrace is a low upland with an elevation up to 8 m. The Ochlockonee and Apalachicola Rivers supply alluvium downdrift to the west that resuns in the development ot a system of beaches, spits, and barrier islands, as well as bars at the river mouths. Within these low-energy zones, marshes are located in the lee of barriers and within bays protected from wave action (Tanner 1960b, Kwan 1969). No baniers are found in the region west of St. Joseph Bay. Moderate-energy waves from the Gulf of Mexico strike the beaches; marshes protect shores only in major bays such as St. Andrew Bay and Choctawhatchee Bay. Steep mainland bluffs along the western shore of Escambia Bay in the Pensacola system do not support broad salt marshes. Marshes occur sporadically along the lagoonal interface of Alligator Point peninsula, especially at the extreme east end of Alligator Harbor (Livingston 1984). Marshes are limited along the mainland east and west of the Apalachicola River mouth. In areal coverage, East Bay marshes dominate the system with lesser marsh development along St. Vincent Sound and the landward portions ol Dog Island arid St. George Island. The marshes of the Apalachicola Bay systemcover approximately 14%of the surface (Livingston 1984). d. Vascular plants present. The saline marshes of the Panhandle are dominated by halophytic monocotyledonous grass or rushlike plants, primarily Juncus roemerianus (black needlerush), Spartina anerniflora (saltmarsh cordgrass), Spartina patens (saltmeadow hay or cordgrass), and Distich/is spicata (salt grass). Fleshy, dicotyledonous plants-Salicornia, Batis, and Borrichictare commonly present but less abundant. Table 17 gives a list of dominant plant species in Panhandle salt marshes. Tidal marshes of the northwest Florida coast aredominated by Juncusroernerianus. Thirtyone percent of the marsh area in the Panhandle is dominated by this species (Eleuterius 1976). The vascular plants form distinctive patterns of species zonationwithin the salt and brackish marshes of the Panhandle. Four zones are discernible: Spartina alterniflora, Juncus roemerianus, salt flat or barren, and high meadow (Stout 1984) (Figure 70A). The Spartina alterniflora zone is closest to sea level inthe intertidalzoneand experiences regularor daily inundation. Sincethis zone is regularlyflooded, substrate salinity is approximately that of tidal concentration. Thezone liestypically withinanelevation from0.24 mto 0.54m MLW. If the shoretopography isbroadandgently sloping, S. alternifloracan exhibit differences in morphology and flowering. Taller plants with flower heads occur in the lower elevations of the zone, while shorter sterile plants occupy the upper area (Stout 1984). The zone is usually monospecific. On shores with greater slope. S. alterniflora may be found mixed with Juncus roemerianus. Shores with greater wave energy may form alevee upslope from the Spartina(Figure 708). The vegetation of the levee is usually typical of higher elevations. The Juncus roernerianus zone is at a slightly higher elevation and subjected to less flooding than the Spartina alterniflorazone (Figure 70A). Juncus comprises the bulk of the biomass in most Panhandle marshes. There is usually a sharp demarcation between the Spartina and Juncus zones. The Juncus-demarcation zone generally corresponds to the MHW mark, but edaphic conditions and bioticfactors may also be important. The Juncus zone occupies a more restricted elevation range (0.54 11-0.75 m MLW) but spans greater horizontal distances than Spartina. The Juncus zone can reach several kilometers in width. Tidal flooding of this zone is irregular and higher elevations may be flooded only during spring or stormtides. Because of longer more frequent periods of exposure and evaporation, interstitial water salinities may be higher in Juncus than Spartina alterniflora zones. The high organic content (and associated acid conditions) of Juncus soils may impede percolation of tidal water and rainwater Into the substrate.
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Pan handle Ecological Characterization ? V) h V) 2 s S ... m F ... same as In above f~gure I 1 0 meters 50 100 Figure 70. Schematic views of gulf coast salt marshes on protected low-energy shorelines (A) and open moderate energy shorelines (B) (after Stout 1984). A Juncus marsh community may be represented by two or more height forms that possibly reflect microhabitat differences in the zone. The tallest plants are nearest the tidal source and so are more frequently flooded. Stem height and diameter decrease with distance from shore, while stem densities and new leaf production increase. Soil texture and salinity gradients may a play role in morphology (Coultas 1 980). There is a decline in sexual reproduction in Juncus and Spartina alterniflora plants at higher elevations in a marsh. The shortest Juncus plants (height 50.5 rn) are usually sterile and are found adjacent to salt flats. Unlike most of the other marsh grasses, J. roemerianus grows throughout the year and represents a climax vegetational type (Eleuterius 1976). The salt flat zone, just upland from the Juncus zone, has a sandy, hypersaline soil and includes portions of the zone vegetated by halophytic species. These ecotonal areas are called "barrens" because they are devoid of plants. This zone is rarely inundated by tidal water and when it is flooded, water quickly percolates through the coarse substrate. Interstitial water salinities are extremely high. The seaward and upland margins of the salt flat are usually mirror images of plant communities on either side of the barrens (Stout 1984). Salt grass
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7. Estuarine, Saltwater We' tland, and Marlne Habltats (Distichlis spicata) extends in parallel stands from the upper edge of the Juncusand the lower edge of the high meadow into the salt flat. As salinities increase toward the barrens, Distichlis no longer grows. Interior to the Distichlis margins of the salt flats only three species occur: Salicornia virginica (perennial); S. bigelovii(annua1) and Batismaritima. All three species are obligate halophytes. The size of the barrens varies with local conditions and may changeover short periodsof time (i.e., days) with rainfall fluctuations and tidal flooding, and over long periods of time with changes in elevation. If salinity decreases within the barrens, seedlings of the annual Salicornia bigeloviiand rhizomes of other salt flat species rapidly colonize the area. The extent of the hiah meadow zone lor hiah zone include: Fimbristylis caroliniana. Scirpus rnbustus. Aster tenuifolius, Phragmites australis. Cynanchum angustifolium, Pluchea sp., and various shrubs (e.g., Baccharis halimifolia, Iva frutescens. and Myrica cerifera). e. Nonvascular (and microbial) plant communlty. The highest density of nonvascular plants is always found on other plants above the soil surface. Twenty-fivespeciesof filamentousfungi occur on Spartina, all of which are on the aboveground parts of the plant. Two infectious fungi occur on Spartina: the ergot fungus Clavicepspurpurea and the rust fungus Puccinia sparganiodes. Of the algal communities found in Panhandle marshes, only diatoms and blue greens of Juncusdominated marshes have been examined (Stout marsh) varies greatly from a narrowly ve$etated 1984). The epiphytic algae Bostrychia spp. and fringe between the salt flat and upland vegetation to Enteromorphaspp. are the most frequently enwuna broad meadow of grasslike vegetation. Juncus is tered (Table 18). Diatoms constitute a continuous usuallv verv abundant and shares dominance with benth~c marsh cover in areas with and without a spartiha the latter being most common upspermatophyte canopy. The most abundant diatom land. This zone contributes most to the diversity of speciesis Naviculatripuncata. Thegreatest number the marsh with numerous incidental species present of diatom species is found on Distichlis spicata, the in the shrub-forest ecotone. Species common in this lowest on Juncus. Diatom distributions are primarily Table 18. Zonal relatlonshlp of algae wlth spermatophyte communlty In Panhandle marshes (from Kurz and Wagner 1957, Stout 1984). Dominant algae Location Dominant algae ~ocation Spartlna alternMlora commur Bostrychia spp. Enteromorpha flexuosa Melosira spp. Microcoleus chthonoplastes Phormidium fragile Lyngbya confervoides soil diatoms Chondria spp. Digenia spp. Enternmopha spp Sargassum spp. Polysiphonia spp. lity attached to culms attached to culms attached to culms channel bottom attached to oyster shells attached to oyster shells sediment drift fragments drift fragments drift fragments drift fragments drift fragments Champia spp. drifl fragments Fosliella spp. drift fragments Juncus memerlanus community Bostrychia spp. attached to culms Cladophora spp. attached to culms Chaetomorpha spp. attached to culms Enteromorpha spp. attached to culms Lyngbya aestuarii attached to culms Dlstlchlls spicata community Bostrychia spp. attached to culms Cladophora spp. attached to culms Chaetomorpha spp. attached to culms Enteromorpha spp. attached to culms Lyngbya aestuarii attached to culms
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7. Estuarine, Saltwater Wetland, and Marine Habitats Table 20. Common fishes of Panhandle salt marshes (Stout 1984). Species Common name Residence status Menidia beryllina Fundulus similis Fundulus grandis Fundulus confluentus Cyprinodon variegatus Adinia xenica Poecilia latipinna L eiostomus xanthurus Lucania parva Anchoa mitchilli Mugil cephalus L agodon rhomboides Tidewater silverside Longnose killifish Gulf killifish Marsh killifish Sheepshead minnow Diamond killifish Sailfin molly Spot Bluefin killifish Bay anchovy Striped mullet Pinfish permanent permanent permanent permanent permanent permanent permanent nursery user permanent nursery user nursery user nursery user and available space, and (5) proximity to estuarine are permanent residents. The marsh offers food and nearshore waters. Panhandle marshes, like sources, nesting areas, and refuges. Wading birds other Gulf of Mexico t'rmrshes, are dominated by and shore birds often feed near the marsh intertidal cyprinodont species (Stout 1984). zone and creeks. Only clapper rails and seaside sparrows nest in the Juncus marshes. The majority A number of reptile species are commonly enof others nest in small trees and shrubs growing on countered in the marsh, but amphibians are not as shell and sand berms or spoil deposits within the well representedCoKlmon reptiles are shown in marsh. Snowy and great egrets are the most abunTable 21. dant nesting species within the brackish marshes. Tricolored herons are the most abundant species in Birds are an important component of the marsh the salt marshes (Stout 984). system. Over 60 species are reported to use habitats within Panhandle salt marshes. Table 22 lists Mammals can be categorized into three major those speciesthat are common, however, only a few groups: (1) marsh residents, (2) inhabitants of the marsh-upland interface, and (3) upland mammals entering the marsh to feed (Table 23). Table 21. Common reptiles of Panhandle salt g. Species of special concern. The American marshes (Stout 1984). bald eagle (Haliaeetus leucocephalus) is listed as federally endangered and occurs in Panhandle salt Species Common name marshes. Malaclemys terrapin pileata Mississippi diamond back terrapin Pseudemys alabarnensis Alabama red-bellied turtle Pseudemys floridana floridanaFlorida coot er Alligator mississippiensis America alligator Nerodia fasciata clarkii Gulf salt marsh water snake h. Trophic dynamicsJinteractions. Marshes are characterized by an extremely high level of primary productivity and, subsequently, serve as the base of the detrital food web for the entire estuarine ecosystem. Few animals feed directly upon live Juncus or Spartina, but marsh detritus that results from the decomposition (both biological and mechanical) of plant material is a rich food source for many marsh and estuarine organisms.
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Panhandle Ecological Characterlzatlon Table 22. Common blrds of Panhandle salt marshes (Stout 1984). Note for Occurrence: P = permanent resident; B = breeding population; M = migrant; W = winter visitor; S = summer resident; C = casual. T = threalened species (State of Florida). Order Specles name Gmiformes Rallus elegans Rallus longirostris Rallus limicola Porzana carolina Coturnicops noveboracensis Laterallus jamaicensis Fulica americana Charadfiiformes Sterna nilotica Sterna forsteri Sterna caspia Charadrius semipalmatus Pluvialis squatarola Catoptrophorus semipalmatus Calidris minutilla Calidris alpina Limnodromus griseus Calidris himantopus Calidris pusilla Calidris mauri Ciconiiformes Ardea herodias occidentalis Ardea herodias Butorides striatus Egretta caerulea Casmerodius albus Egretla thula Egretta tricolor Nycticorax nycticorax Eudocimus albus Anseriformes Anas rubripes Anas strepera Anas americana Aylhya americana Aythya affinis Branta canadensis Passeriformes Tachycineta bicolor Corvus ossifragus Cistothorus paluslris Cistothorus platensis Agelaius phoeniceus Ammodramus caudacutus Ammodramus maritimus Common name Occurrence King rail PB Clapper rail PB Virginia rail MW Sora MW Yellow rail W Black rail PB American coot PB Gull-billed tern M Forsteis tern PB Caspian tern W Semipalmated plover W Black-bellied plover WM Willet MB Least sandpiper WM Dunlin WM Short-billed dowitcher SM Stilt sandpiper M Semipalmated sandpiper M Westem sandpiper WM Great white heron Great blue heron ;;BS(T) Green-backed heron SB Little blue heron PB Great egret PB Snowy egret PB Tricolored heron SB Black-crowned night heron PB White ibis S American black duck PB Gadwall W American wigeon W Redhead MW Lesser scaup MW Canada goose MW Tree swallow M Fish crow PB Marsh wren PB Sedge wren W Red-winged blackbird PB Sharp-tailed sparrow PB Seaside sparrow PB
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7. Estuarine, Saltwater Wetland, and Marine Habitats Table 23. Common mammals of Panhandle saII marshes (Stout 1984). Species Common name I Common name Sylvilagus palusrris palustris Marsh rabbit Oryzomys palustris palustris Rice rat Sigmodon hispidus Cotton rat Ondarra zibethicus rivalicius Louisiana muskrat Myocastor coypus bonariensis Nutria Procyon lotor varius Raccoon Mustela vison mink Southern mink Lutra cf. canadensis Otter Vulpes fulva Red Fox Musrela frenara Long-tailed weasel Lynx rufus Bobcat Odocoileus sp. Deer Decomposition rates vary among the different plant species. The available detritus is usually lowest in winter months and increases through the spring and early summer to maximum values in August and September (Stout 1984). I. Natural Impacts. Several natural factors such as sea level rise, extreme climatic events, tidal scour, and fire have affected the ability of marsh habitats to remain funct~onal. Thecurrentandfuturesealevel rise (andcoastal subsidence) may represent the most important potential long-range impact on salt marshes. Estimates of sea-level rise inthe Panhandle (i.e.. Pensacola) range from 84 to 104 cm in the next 100 years (including local subsidence rate and water-level increase) (Titus et al. 1984). Sea-level rise will affect salt marshes in two ways: (1) increased tidal flooding and (2) wave-induced erosion (Titus et al. 1984). Since tidal flooding is an essential component of salt marshfunctioning, any alteration can substantially change the System. With increased flooding, the system tends to migrate upward and landward When insufficient organic sediment or peat is added to the marsh to keep up with the sea-level rise, the seaward zone becomes flooded so that the vegetation drowns and the soil erodes; the high marsh zone eventually becomes the low marsh or open water. Sedimentation from rivers canoffset some of the sea-level rise, but probably only for marshes in major river deltas (e.g .the Apalachicola). Other marshes will have a tendency to move inland. If there is human development just inland from the salt marshes, however, the marshes will have no room to migrate and will eventually disappear. Sea-level rise may increase wave-induced erosion by allowing larger waves to h'n the shoreline. A rise in sea level deepens bays and, depending upon bottom topography, would allow larger locally formed waves and ocean waves to strike the marsh. In addition, the protective barrier islands will rapidly erode and no longer buffer the wave energy before it strikes the coast. j. Human Impacts. Marshes are extremely sensitive and susceptible to oil pollution. Given their location, they can be atfected by oil residue funning off the land as well as by oil spilled in the Guil of Mexico and estuarine waters. Primary productivity can be severely reduced for months after a spill (Stout 1984). Contamination is usually restricted to the outer fringes of the marsh unless storms or extreme hlgh tides drive water higher than usual. Usually, contamination will be apparent on the surface of the soil, plant stems, and leaves. The extent of an oil spill Impact depends upon the amount and type of petroleum spilled, the proximity of the spill to the marsh, and otherfactors. The sublethal effects may bechronicoracute. Thetrophiceffecton marsh birds and other animals higher in the food chain is not well known. Pulp-mill effluents in the Apalachee Bay to the east of the study area have been found to severely reduce both the numberof species and of individuals of marsh fishes. In addition, community structure was altered (Livingston 1975). Bird populations also
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Panhandle Ecologlcal Characterization exhibited reduced abundances and species numbers in pulp-mill polluted areas (Weiser 1973). Sediment diversions such as dams, canals, and levees (e.g., fill roads) impact wetlands by decreasing the supply of fine sediment essential for the maintenanceof marsh substrate. If an area is naturally subsiding, a reduced sediment supply from the land magnifies the problem. Theextraction of ground water, oil, andgas may cause subsidence of the local area. Also, impounding a marsh causes consolidation and oxidation of dewatered sediments. Other human activities with more localized effects include: using pesticides (Tagatz et al. 1974), erosion from boat-wakes, canal dredging, using marsh buggies and other wetland transportation vehicles, and waste disposal. k. Conclusions. The salt marsh is a critical nursery, refuge, and feeding area for many commercially important estuarineorganisms such as fish and crabs. The plants protect the juvenile forms of many of the estuarine organisms against predation. They also supply the bulk of the detritus for the estuarine system. They have the important function of buffering coastal regions from the erosional effects of storms. The balance between a rising sea level and the necessary sediment supply is being upset by human encroachment in nearby habitats that directly and indirectly affects the marsh. This habitat is one that requires very stringent monitoring for future protection. 7.2.4 lntenldai Flats a. introduction. lntertidal flats are those portions of the unvegetated bottoms of estuaries, bays, lagoons, and river mouths that lie between the high and low tide marks as defined by the extremes of spring tides (Peterson and Peterson 1979). Intertidal flats are composed of sandy and muddy sediments in a wide range of relative proportions. Usually the distinction between intertidal "sand"flats and "mud flats (as nearly all intertidal flats are traditionally misnamed) is made upon percentage of silt-clay in the sediment: sediment sllt-clav fractlon (dm wt.) clean sands < 5% muddy sands 560% sandy muds 50-90% tlue muds > 90% The sediment type is indicative of the energy level of the coastline (i.e., a muddy sediment usually means a low-energy shore). lntertidal flats appear barren and unproductive because of the absence of macrophytes such as marsh grass or seagrass. However, benthic microalgae are very abundant and productive, but do not accumulate the great biomass that, for example, marsh grasses do. Microaigae are nutritious and highly palatable to many herbivores; they are therefore rapidly used and maintain a low standing stock. Benthic microalgae generally do not go through intermediate bacterial or fungal food chains but are consumed directly by benthic invertebrates. For these reasons, intertidal flats contribute a substantial amount of primary productivity to an estuarine system which is, in turn, converted into consumer biomass. The benthic invertebrates are preyed upon by larger predators such as shorebirds, crabs, and bottom-feeding fishes. lntertidal flats play a critical role in the functioning of the entire estuarine system (Peterson 1981). b. Flora. Microalgae, bacteria, and fungi are locally abundant on intertidal flats. The generally small sediment particles present in the intertidal habitat can support large populations of these organisms. Occasionally, the bacteria form visible purpllsh-red mats on the sediment surface (Reidenauer, personal observation). Bacteria are an important food source for the meiofaunal community (Carman 1984) and are the primary transformers of detritus into inorganic nutrients. c. Faunal composition. Two groups of benthic fauna are present on the intertidal fiats: epifauna (forms that live on top of the substrate) and infauna (forms that live within the substrate) (Figure 72). Mobile epifauna, such as crabs, are found most commonly during high tides. lnfaunal organisms, however, are more abundant at both low and high tides.
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7. Estuarine, Saltwater Wetland, and Marine Habitats Surface deposit feeders A = Spiophanes bombyx (spionid polychaete) B = Ptychodera bahamensis (protochordate) E = Prionospio steenstrupi (spionid polychaete) Suspension Feeders F = Protohaustorius sp. (haustorid amphipod) G = Gemma gemma (venerid bivalve) K = Acanthohaustorius sp. (haustorid amphipod) Conveyor-belt deposit feeder L = Clymenella torquata (maldanid polychaete) Burrowing deposit feeders C = Aricidea cerrutii (paraonid polychaete) D = oligochaete H = Exogone dispar (syllid polychaete) I = Haploscoloplos f ragilis (orbiniid polychaete) J = Nephtys picts (nephtyid polychaete) Figure 72. A cross-sectional view through a typical intertidal sand-flat community In the Panhandle showing representative invertebrates (adapted from Whitlatch 1982). The infaunal microfauna are dominated by protozoans, with foraminifera and ciliates being the dominant forms. The group has been little studied. The meiofauna differ between sand and mud tidal flats because of the difference in interstitial space (i.e., space between sediment particles) available to the organisms in each sediment type. Sand sediments have larger interstitial spaces and the majority of the meiofauna are adapted to living within these spaces (i.e., infaunal). In muddy sediments, the meiofauna are generally restricted to living on the sediment surface (i.e., epifaunal). The macrofauna are the most dominant group of infauna in terms of biomass present. Polychaetes, amphipods, enteropneusts, and bivalve and gastropod mollusks dominate the community (Figure 72 and Table 24). d. Trophic dynamics and interactions. Microalgae, primarily the diatoms, dinoflagellates, filamentous greens, and blue-greens, are the primary products in the tidal flat system. Typically, these forms demonstrate a high turnover rate. Herbivores are usually deposit-feeding or grazing macroinvertebrates. Many of the common species are given in
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Panhandle Ecologlcal Characterization Table 24. Commonly encountered macrolnTable25. CommonbirdsofPanhandle venebrates of Panhandle intenldal flats (Abele lntenidal flats (Stout 1984). 1970, LeBlanc 1973, Abele and Kim 1986). Guild Common name Group species Habitat Waders Herons Crustacea Alpheus heterochaelis epifaunal Egrets Callianassa jamaicensis infaunal Ibises Eurytium limosum epifaunal Yellowlegs Uca longisignalis eplaunal Sandpipers Callinectes sapidus eplaunal Plovers Mollusca Mercenaria mercenaria infaunal Knots Polychaeta Amphicteis gunner; floridus infaunal Deep-probing Godwits Dropatra cuprea infaunal Willets Glycera americana infaunal Curlews Glycera dibranchiata infaunal Hapbswplos fragilis infaunal Aerial-searching Tems Heteromastus filiformis infaunal Gulls Laeonereis culveri infaunal Skimmers Notomastus latericeus infaunal Pelicans Onuphis eremita oculata infaunal Floatingldiving Ducks Pectinaria gouldii infaunal Geese EnteropPtychodera bahamensis infaunal Grebes neusta Cormorants MerostoL!mulus polyphemus epifaunal Birds Of prey Osprey mata Eagles Table 24. Shorebirds (Table 25), crabs. and fishes are the primary consumers of the herbivores. The infauna of Panhandle intertidal flats are generally less abundant than that of adjacent salt marshes, even at similar tidal heights. The difference is usually pronounced and approaches two orders of magnitude (Stout 1984). The pattern appears to be a result of higher predation on organisms living in the flat areas (Naqvi 1968). Large, mob~le epibenlhicpredatorsarecommon on intertidal flats, especially during the warm summer months when most infaunal organisms are low In numbers. Predators can be divided into two general groups One group, dominated by fiddler crabs (Ucaspp.), roamsthe intertidalzone at lowtide foraging for epibenthic algae and detritus. Most of the members in this group are herbivores or detritivores. The other groupof predators includes organisms that forageon the flatwhen the tide is in. These species are mostly carnivorous. The most important species are the blue crab, Callinectes sapidus, the stingray, Dasyatis sabina, and the horseshoe crab, Limulus polyphemus. These species prey on bivalves and polychaetes. The toleranceof blue crabs to reduced salinities makes them effective predators under a variety of conditions. Blue crabs cannot forage efficiently for infauna in the presence of shell debris, which inhibits their digging; therefore, the abundance of many bivalves and other infauna is higher at the margins of structures such as oyster reefs. Smaller biological structures, such as Diopatra cuprea tubes, may also offer infaunal organisms a refuge from predationor disturbance (Woodin
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7. Estuarine, Saltwater Wetland, and Marlne Habltats 1978). In addition to the inveltebrate predators, The first macrofaunal colonizers onto a new birds are important predatorson infaunal organisms. hard substrateare usually the Arnericanoyster Crassostrea viginica or the barnacle Balanus spp. The In addition to removing organisms by predation, barnacle can eventually replace the oyster. blue crabs, horseshoe crabs, and birds can be a source of infaunal mortality by disrupting the sediment surface. Blue crabs dig up to 6-8 cm deep in the sediments to forage and hide. Their pits are sites of decreased infaunal densities (Woodin 1978). Horseshoe crabs dig broad, shallower pits (less than 4 cm deep) that have slightly less impact on the infauna (Peterson and Peterson 1979). Birdsdisturb the infauna in a variety of ways depending on their feeding mode. c. Trophlc dynarnlcs and interactions. Predators on the initial colonizers of hard substrates appear quickly after settlement. Oyster predators include the Americanoystercatcher (Haernatopuspalliatus), the decapodsdlue crab, stone crab (Menippe mercenaria), and mud crab (Eurypanopeus depressus), and the mollusk--oyster drill (Thais haemastoma). Barnacle predators include the decapods Pachygrapsus transversus, Mithrax forceps, and M pleuracanthus. Decapods are Additional food resources are supplied to the common On panhandle jetties (Table 26). intertidal flats by grass wrack (dead fragments of seagrass and marshgrass) that are deposited on the K. Sherman (Florida Department Of Health and flat during outgoing and incoming tides. Rehabilitative Services, Tallahassee; pers. comm.) has investioated the e~ifauna of live scallo~ shells 7.2.5 Hard Substrates a. Introduction. Most of the habitat represented in this category is artificial. There is little naturally occurring hard substrate along the Panhandle coast. In addition to larger surfaces such as jetties, bridges, and pier pilings, mollusk shells and trash offer suitable microhabitats for some sessile orpanisms. b. Community structure. Panhandle estuarine fouling communities demonstrate a dramatic decrease in lava1 settlement and population growth during the winter (November-March) (Salsman and Ciesluk 1978). The entire fouling community appears to be affected except the bacteria and associated slime film (including algae) that is usually present. During the summer, when water temperatures are greater than approximately 20 "C, a complete biofouling community is present. The most abundant organisms are barnacles, with the species Balanus eburneusdominant in the upper tidal zone. Polychaetes (serpulids and spirorbids+alcareous tube builders) and bryozoans are also abundant. Later in community development, tunicates (ascidians) become important. Tunicates, or sea squirts, (e.g., Ectenascidia turbinataand Styellapartita) can eventually dominateasubstrate,forminga homogenous layer 30-40 mm thick. from St. ~oieph Bay. ihe epifaunal assemblage is similar to the nearby Thalassiaepifauna but is dominated by different species. There is a strong seasonality, and competition for food may be an important factor in controlling abundances (especially meidauna). The two-dimensional natureof the hard substrate may result in spatial competition among the various residents (K. Sherman, pers. comm.). 7.2.6 Ovster Reefs a. Introduction. The biology of the oyster has been extensively studied because of economic interests (e.g.. meat and shell industries). However, the ecology of the oyster reef ecosystem, despite recognition that it is aseparatecommunity (Mobius 1877), has not been nearly as intensively investigated. Most information comes from research performed outside the Panhandle region. Oysters are typically reef organisms, growing onthe shell substrate accumulated from generations of oysters (Chestnut 1974). The term oyster reef is often used interchangeably with other terms for estuarine regions inhabited by oysters, including oyster bar, oyster bed, oyster rock, oyster ground, andoysterplanting. Bahr and Lanier (1981, p. 3) define oyster reefs as 'The natural structure found between the tide lines that are [sic] composed of oyster shell, live oyster, and other organisms and that are discrete, contiguous, andclearly distinguishable (duringthe ebb tide) from scattered oysters in marshes and mud flats, and from wave-formed shell windrows."
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Panhandle Ecological Characterization Table 26. Common decapods found on Panhandle jetlles (Abele 1970, Abele and Kim 1986). S~ecles name I Soecles name I Soecies name Oyster reefs influence estuaries physically by and Patten 1981). Overall, filter feeders (e.g.. the removing suspended particulate matter and changoysters) affect nutrient cycling and energy flow in the ing current patterns, and biologically by removing ecosystem through translocation and transformaphytoplankton and other particles and producing tion of matter (Dame 1976). large quantitiesof oyster biomass and pseudofeces. Acanthonyx petiverii Alpheus armillatus Alpheus formosus Calcinus tibicen Dromidia antillensis Hexapanopeus paulensis ~n addition, the structure of the reef provides habitats b. Distrlbutlon. Oyster reefs are present in formany esluarineorganisms. One square meterof many of the Panhandle estuaries (Table 27). In the a typical oyster reef actually represents approximately 50 m2 of surlace area or potential habitat (Bahr and Lanier 1981). Hexapanopeus quinquedentatus Hippolysmata wurdemanni Mithrax forcep Mithrax pleuracanthus Pagurus miamensis The oyster reef is a strongly heterotrophic systemusing tidal energy to bring in food andcarry away waste material. The majority of energy or matter entering or leaving the oyster reef is surficial (filter feeders, detritus, and predatorcomponents) and not contained within complex food web networks (Dame Periclemenes americanus Poftunus sayi Sicyonia laevigata Stenorhynchus seticornis Synalpheus fritzmuelleri Xantho denticulata Apalachicola Bay system, oyster reefs cover an estimated 7% of the bottom area (Livingston 1984a). Newly constructed artificial reefs are located primarily in the eastern portions of St. Vincent Sound. The natural reefs of St. Vincent Sound and western St. George Sound represent the largest concentrations of commercial oysters in the Panhandle. It is estimated that 40% of Apalachicola Bay IS suitable for growing oysters, but that substrate type is a major limiting factor (Whitfield and Beaumarriage 1977). Table 27. Area of oyster reefs (beds) In the Florlda Panhandle (from (a) McNulty el al. 1972, (b) Llvingston 1984). Oyster reef Oyster reef Area coverage (ha) Source Area coverage (ha) Source Ochlockonee Bay ? East Bay (St. Andrew) 46 a Alligator Harbor 36.7 a St. Andrew Bay 0 a St. George Sound (East) 2.6 b West Bay 7 a St. George Sound (West) 1,488.8 b Noiih~ay 6 a East Bay 66.6 b Choctawhatchee Bay 4,695 a Apalachicola Bay 1,658.5 b Santa Rosa Sound 0 a St. Vincent Sound 1,096.5 b East Bay (Pensacola) 3,395 a St. Joseph Bay 0 a Escambia Bay 81 a St. Andrew Sound 0 a Pensacola Bay 0 a 194
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7. Estuarlns, Saltwater Wetland, and Marlne Habitats The system is characterized by very rapid oyster reproduction and growth, accounting for approximately 90% of Florida's and 8%-10% of the nation's annual oyster production. Choctawhatchee Bay also possesses a fairly extensive coverage of oyster reefs (Burch 1983b). The oyster beds are harvested in Wanon County west of the U.S. Highway 331 causeway along the southern shore of the bay. c. Oyster autecology. The primary reef-building, commercial oysterfound in the Panhandle isthe Eastern or American oyster. The species Ostrea equestris is also present. Both species grow in a wide salinity range (10-30 ppt). Optimal growth occurs at a water temperature of approximately 25 "C. The oyster is dioecious (i.e., having separate sexes), but once a year some members can undergo protandry (change from male to female) or protogyny (female to male). It has been postulated that under certain types of stress a population may developa higherproportionof rnalesthanfemales For instance, the harsh conditions in the higher portions of the oysters' intertidal range (the upper reef zone) may produceor regrow predominantly malecolonies that would contribute little to the reproductive success of the population. Temperature or salinity shock usually triggers the emission of sperm from mature males in a local population. The threshold temperature or salinity can vary among geographic locations. Emission of the sperm from male oysters stimulates the females in the area to release eggs via a chemical cue (protein pheromone). A mass 'thain reaction" spawning can occur in dense populations. Fenilization occurs in the water column through the chance meetings of egg and sperm. This begins the planktonic, free-living phase of the oyster life cycle. When the larva first secretes a oair of shells it Point and in Alligator Harbor along the Panhandle coast. He reported that oysters 1 year of age and older undergo two major spawning periods per year with renewed gonadal development between these events. In addition, oysters that set early in the spawning season reach sexual maturity and spawn before the end of the same reproductive season. The gonadal condition of established oyster populations depends on ambient water temperatures. In the eastern part of the Panhandle, gonadal development begins before the temperature reaches 20 OC (usually in April), probably sometime in late February or March (Hayes 1979). The majority of spawning does not occur until a minimum temperature of 25 "C is reached. Spawning can also be induced by temperature fluctuations of 5-10 "C. Gamete-containing gonads in established oysters are still present in late October and probably remain active until late November when most gonadal activity ceases (Hayes 1979). Most of the setting occurs in the spring (late May). This peak can be attributed solely to the spawning of those oysters that attached in previous years (i.e., at least 1 year old). Setting that takes place later in the season may be due to additional spawning by older oysters and spawning of the sexually developed young-of-the-year oysters. The contribution of the young oysters to population recruitment, however, is minimal. A number of physicochemical and biological factors influence the settlement of larval oysters. Light, salinity, temperature, and current velocity are of primary importance. In addition, oyster larvae are highly gregarious and settle in response to a waterborne pheromone or metabolite that is released by the oyster after metamorphosis. Larvae are also attracted to a protein on the surface of oyster shells. The gregariousness is critical since the reproductive schemeof the ovsterreauires settlement in ~roximitv -. . reaches the veliger stage. Dep;nding in water for SUCC~SS~U~ fertilization. temperature and food availability, the larval stages usually lasts710 lodays, but insomecasesmay last Oyster growth occurs throughout the year in the up to two months. Panhandle (Menzel et al. 1966). Maximum size (total shell length) IS usually not much greater than Hayes (1979) studied the reproductive cycle of 100 mm Oysters reach a marketable size within 2 the American oyster in intertidal areas off Turkey to 3 years after settlement.
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Panhandle Ecologlcal Characterlratlon Oystersarefilter-feeders. Thespecificdiet isnot clearly known. The gills are repoiled to selectively retain diatoms, dinoflagellates, and graphite particles from 2 to 3 microns (Bahr and Lanier 1981). Feeding activity is highest at low food concentrations and there isa negative correlation between pumping rate and surrounding turbidity. Because they filter the water to feed, oysters can concentrate pathogenic bacteria and viruses along wiih food particles. d. Oyster reef development and zonation. Oyster reefs in the Panhandle range in size from small scattered clumps to massive solid mounds of living oysters and dead shells. Reef development is usually limited to the middle portion of the intertidal zone, where minimum inundation time determines the maximum elevation of reef growth. Predation and siltation (which determines available substrate) are the main factors that often limit oyster populations in the lower intertidal and subtidal zones to scattered individuals and small clumps. An oyster reef may begin its development with the attachment of a single oyster to some solid substrate. Succeeding generations of oysters attach tothe earlier colonizers and a gradual increase in length, width, and height eventually forms a reef. In shallow intertidal water, such development can form a marsh island with a fringe of live oysters. In deeper water, a reef may form a shoal rising several feet above the bottom. There is a difference in the size of oysters from the variousparlsof a reef. Individuals along the edge are usually larger (i.e., longer shell length) than those in the center (Menzel et al. 1966). This difference in growth can be as high as two-fold. During exposure to the atmosphere (at ebbtide), the surface of a reef dries and turns gray, but, upon wettlng, the thin film of algae covering the shells appears greenish-brown. Only the upper layer (5-10 cm) of oysters and dead shells actually dries out. The underlying shell layer remains moist. The reef consists of three "horizons" (Bahr and Lanier 1981): (1) pale greenish-gray (theexposedportion); (2) reddish-brown; and (3) silver-black. The reddishbrown section derives its characteristic color from the detritus covering each shell. It lacks the film of algae characteristic of the upper layer. The silverblack zone is characteristic of shells buried in an anaerobic environment high in ferrous sulfide. Mud crabs (e.g., Panopeus herbstii and Eurypanopeus depressus) graze on the organic film in the top two horizons. A section through a typical Panhandle oyster reef shows that it has relatively distinct strata (Bahr and Lanier 1981). The moist upper portion is level, but the reef slopes steeply at the edges. The living portion of the reef is thicker at the perimeter than in the center, where mud trapped by biodeposition and sedimentation may smother oysters. This sedimentation results from suspended matter settling out as turbidwater slows down while passing overthe reef. Oysters in the top (green) layer have sharper growing edges than those in the reddish-brown zone, indicating faster growth. This is a resull of crowding and sediment deposition on lower oysters. e. Associated fauna. Vertical zonation in oyster reef macrofauna is caused by the differingtolerance to desiccation of the various species rather than by their differing requirementsfor inundation in order to feed (Bahr and Lanier 1981). Some of the same zonation patterns are reflected on artificial pilings. In a manner similar to that of the reef, single shell or live oyster on that reef maintains a microcosm of sessile and mobile epifauna. The reef provides a solid substrate for sessile organisms that require an attachment surface. These include algae, hydroids, btyozoans, barnacles, mussels, and polychaetes. Some forms also bore into the shell: boring sponges and mllusks. perforating algae, and burrowing polychaetes. Many organisms find refuge in the crevices of the reef. Organisms typically found on Panhandle oysters reefs are given in Table 28 (Menzel and Nichy 1958, Menzel et al. 1966, Abele 1970, Livingston 1984, Abele and Kim 1986). The stone crab is a commercially important inhabitant of oyster reefs. Stone crab densities on oyster reefs are highest during the summer, decline over the late fall, and remain low throughout the winter (Hembree 1984) (Figure 73). Seasonal residency patterns suggest that the reefs may provide a
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1. Estuarine, Saltwater Wetland, and Marine Habltats Table28. Common faunaof a Panhandleoysterreef (Menzel and Nlchy 1958, Menzel et al. 1966, Abele 1970, Livingston 1984, Abele and Klm 1986). Group species I Group Species MicrofaunalMelofauna Fungus Perkinsus marinus Macrofauna Poriiera Cliona vastifica Coelenterata Astrangia spp. Bryozoa Mebranipora sp. Platyhelminthes Bucephalus cuculus Stylochus frontalis lnsecta Anurida maritima Annelida Neanthes succinea (Polychaeta) Polydora websteri Sabellaria spp. Arthropoda Balanus eburneus Callinectes sapidus Clibinarius vittatus Eurypanopeus depressus Menippe mercenaria Neopanope packardi Neopanope texana Panopeus herbstii Petrolisthes armatus Synalpheus minus Mollusca Anachis obesa (Gastropoda) Busycon wntrarium Creprdula plana Epitonium sp. Gastropoda (cont.) Kurtziella sp. Melongena wmna MitreNa lunata Murex pomum Odostonia impressa Pleuroploca gigantea Polinices duplicatus Seila adamsi Thais haemastoma Triphura nlgrocincta Mollusca Abra aequalis (Pelecypoda) Anadara transversa Anomia simplex Branchidontes exustus Branchidontes recurvus Chione cancellata Crassostrea virginica Corbicula sp. Marfesia smithi Mulinia lateralis Noetia ponderosa Ostrea equestris Semele bellastriata Trachycardium muriacaturn Fishes Hypleurochilus germinatus Hypsoblennius hentzi Hyspoblennius ianthus Opsanus beta Birds Haematopus palliatus valuable site for reproductive activities. Juvenile crabs are abundant on reefs, which act as shelters from predation and offer food resources in the form of reef-associated organisms (i.e., bivalves, gastropods, and crustaceans). Hembree (1984) reported that the adult inshore residency peaked in the fall (Figure 74) and that adult heterosexual pairing of stone crabs on the oyster reefscoincides exclusively with the fall mating season, and suggested that oyster reefs provide a valuable resource for the stonecrab, e.g., a highdensity of potential mates and suitable shelter for molting. The stone crab fishery is concentrated in the nearshore areasofthecoast. Thecommercial stone crab season is from October 15 to May 15. Only claws with a minimum of 7 cm propodus length or 10.8 cm overall length may be kept. f. Commercial aspects. In the Panhandle (as well as in the entire State) oyster reefs are considered public unless yearly leases are obtained from the Department of Natural Resources. The primary advantage of leasing is the ability to designate an area and plant oyster shells or other culch material
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7. Estuarine, Saltwater Wetland, and Marlne Habltats Table 31. Common planktonicorganlsmsfound In Panhandleestuarlne open waters (Estabrook 1973, Edmlston 1979). Group Specles Phytoplankton Diatoms Bacterrastrum delicatulum Bacteriastrum varians Cerataulina pelagica Chaetocerus deciphens Chaetocerus lorengianum Coscinodiscus radiatus Hemiaulus hauckii Hemiaulus sinensis Melosira sulcata Nitzschra closterium Rhizosolenia alata Rhizosolenia stolterfothii Skeletonema costalum Thalassionema nitzschioides Thalassidthrix frauenfeldii Dinoflagellates Ceratium tripos Gonyaulax balechii Peridinium depressum Coccolithophores Pontosphera spp. Zooplankton Copepods (Calanoids) Acartia tonsa Anomalocera ornata feeding takes place in the early morning or evening. Red d~m have been observed 'Tailing" in shallow areas, rooting about with heads lowered and tails occasionally out of the water. Group Specles (Cyclopoids) Corycaeus americanus Oithona brevicornis Oithona nana Oithona simplex Crab 'Oeae Larvacean Oikopleura dioica Polychaeta larvae Spionidae Phyllodocidae Rotifer Synchaeta sp. cladocerans Chaetognaths Sagina helenae Sagitta hispida Sagina tenuis Echinoderm larvae Mellita quinquiesperforata Ctenophores Beroe ovata Mnemio~sis mccradvi Coelenterates Aurelia spp. Chrysaora spp. Stomolophus spp. Labidocera aestiva ~araca~anus crassirostris Paracalanus parva Red drum are harvested in a mixed-species fishery, using a variety of gear including haul seines (common and long), fish trawls, pound nets, gill nets, hand lines, trammel nets, and shrimp trawls. Runaround gill nets are the predominant gear used in the Panhandle. Highest landings are generally recorded in the fall and early winter. Recreational fishermen generally find shrimp, squid (Loliguncula Various fish eggs and larvae spp.), cut mullet (Mugil spp.), spot, herring (Clupeidae), ormenhaden good bait for reddrum. An 18inch limit is set by the State of Florida for red drum. Currently the commercial take of red drum in Florida is banned and the recreational take restricted by the State and regulations regarding take should be checked. (3) Spotted seatrout. The spotted seatrout is a nonmigratory euryhaline estuarine species that is most abundant in the confines of semilocked lagoons andquiet estuaries. It has aprotracted spring and summer spawning season that peaks in late
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Panhandle Ecological Charsaerlzatlon Table 32. Common nektonlc forms tound In Panhandle estuarlne open waten. Group Specles Common name Squid Lolliguncula brevis Brief squid Fish Anchoa hepsetus Striped anchovy Anchoa mitchilli Bay anchovy Archosargus probatocephalus Sheepshead Arius felis Sea catfish Bagre marinus Gafftopsail calfish Bairdiella chrysoura Silver perch Brevooflia patronus Gulf menhaden Cynoscion arenarius Sand seatmut Cynoscion nebubsus Spotted seatrout Echeneis naucrates Remora Elops saurus Ladyfish LeiOStomuS xanthurus Menidia beryllina spot Silverside Menticirrhus americanus Southern kingfish Menticirrhus littoralis Gulf kingfish Micropogonias undulatus Atlantic cmaker Monocanthus hispidus Planehead filefish Mugil cephalus Striped mullet Pogonias cromis Black d~m Sciaenops ocellatus Red drum Urophycis floridana Southern hake Sharks Carcharhinus acronotus Blacknose shark Carcharhinus isodon Finetooth shark Carcharhinus leucas Bull shark Carcharhinus limbatus Blacktip shark Rhizoprionodon terraenovae Atlantic sharpnose shark Sphyrna lewini Scalloped hammerhead Sphyrna tiburo Bonnethead Tunles Caretta carefta Loggerhead Dermochelys mriacea Leatherbad Porpoise Tursiops truncatus Bottlenose dolphin Aprilto July. Young-of-the-yearspottedseatroutare mullet, pinfish (Lagodon rhomboides), and silvergenerally associated with seagrass beds in estuarsides (Menidia beryllina)). Food habits change with ies. age. Copepods are important prey for fish less than 30 mm TL. Larger crustaceans are important prey Spotted seatrout are carnivorous, feeding prifor fish less than approximately 275 mm SL (stanmarily on crustaceans (penaeid shrimp and crabs) dard length). Larger specimens predominately eat and fish (anchovies (Anchoa spp.), menhaden, fish.
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7. Estuarine, Saltwater Wetland, and Marlno Habltats There are seasonal changes in the types of commercial gear used in the Panhandle. Trammel nets and haul seines are primarily used near river mouths during the winter months. Hook and line fishing is productive throughout most of the year, whereas trolling is usually best in the fall. The best gilland trammel-net fishing Is from mid-November to mid-February when the fish congregate in deep holes. Recreational spotted seatrout fishing includes bridge, skiff, and shoreline fishing. Live bait, including shrimp, sailors choice, pinfish, mullet, and needlefish (Strongylura marina), is generally used with greater success than are lures. Fishing usually takes place year round in the Panhandle. It is one of the most sought after and most frequently caught species of sportfish. A 12-inch minimum size limit is set by the State of Florida for spotted seatrout. (4) Gulf menhaden. The gulf menhaden supports a large fishery in the gulfand its young are prey formany otherspecies of sport orcommercial importance (Tagatz and Wilkens 1973). Spawning occurs in the open gulf. Larvae spend 3-5 weeks offshore before moving into estuaries at 9-25 mm SL. After transformation, juveniles remain in low-salinity nearshore areas where they travel in dense schools near the surface. The schooling behavior is retained throughout life. Feeding behavior changes from selective, particulate-feeding carnivory tofiiler-feeding with age. Adult and mature juveniles emigrate from estuaries to gulf waters primarily from October to January. Gulf menhaden is a short-lived species. Individuals rarely exceed 2 years of age. The fishery season runs from mid-April to October when the fish are inshore and sexually inactive. (5) Atlantic croaker. The Atlantic croaker is a target species01 the industrialgroundfishfishery and is often dominant in inshore and offshore sport catches. The species is considered estuarine dependent because all stages from larvae to adultsare known to occur in abundance in estuarine waters. Postlarvae and juveniles grow rapidly in estuarine nursery grounds and are subject to predation by several other species (Kobylinski and Sheridan 1979). The species has a protracted spawning season from October to March with a peak in November. After hatching, larvae and postlarvae may spend some time as plankton, but eventually become demersal. The schooling behavior is maintained throughout life. The heaviest concentrationsof adult Atlantic croaker are found at river mouths. Marshes are very important to juvenile development. (6) Sea catfish and gafftopsail catfish (Arius felis and Bagre marinus). The sea Gaff ish and gafftopsail catfish are not favored sport or food fishes, but their widespread abundance and distribution cause them to rank high in trawl and angler catches in the Panhandle. Commercial and sport fishermen consider both species to be nuisances and dangerous. Toxic substances from sea catfish spines are quite virulent. Copious slimy mucus secreted by the gafftopsailcatfish is aproblem in nets andto humans handling the fish. The oral gestation behaviorof the two species is of scientitic interest. The male carries the fertilized eggs, larvae, and small juveniles in its mouth. The distribution and abundance of the two species in gun coastal and estuarine waters is related to spawning activities, as well as water temperatures and salinities. Adults avoid lower temperatures by migrating offshore in winter and returning inshore in spring. Both species are opportunistic feeders over submerged mud and sand flats. Stomach contents generally include algae, seagrasses, coelenterates, holothurians, gastropods, polychaetes, crustaceans, and fish. Scavenging may also be indicated, since large fish scales and human galbage have been reported from some individuals. (7) Bay anchovy and striped anchovy (Anchoa mifchill~ and Anchoa hepsetus). Both species are important prey species that spawn in the estuaries. They are not of direct commercial importance (as human food). The mnths of peak abundance vary, but anchovies are generally common from spring through early winter in Panhandle waters. Both species primarily feed on zooplankton such as calanoid copepods, mysids, and cladocerans (Sheridan 1 978).
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Panhandle Ecologlcal Characterlzatlon d. Specles of speclal concern. The salmarsh topminnow Fundulus jenkinsi (Everman) is found in Escambia. East, and Blackwater Baysof the Pensacola estuarine system (Gilbert 1978). It is knownto live in salt, fresh, and brackish water (salinity range 3.4-24 ppt). It prefers protected tidal ponds, creeks, and marsh areas near river mouths and possibly son mud substrates. It has been recorded only a few times in Florida waters, and the aforementioned bays may represent the species' easternmost occurrence. Two species of turtle are occasionally present in the Panhandle estuaries: the Atlantic loggerhead Careffa carefta and Atlantic leatherback Dermochelys coriacea. Loggerhead turtles nest yearly during summer months on many Panhandle beaches (Harris et al. 1984). e. Natural Impacts. Red tide outbreaks occasionally occur within estuarine waters in the Panhandle. The primary components are dinoflagellates, primarily Ptychodiscus brevis (formerly Gymnodinium breve) and Gonyaulax monilata. In addition, storms and localized temperature and salinity fluctuations affect the water column organisms (Bortone 1976). 1. Human Impacts. Petroleum pollution is a primary artificial impact. The input of an oil spill is usually considered lesssevereon openwaterorganisms (at least adult forms) since many can avoid the spill itself (i.e., the nektonic forms can swim away). The effect on planktonic forms is not well established. Productivity is reported to decline immediately after a spill. Apossible important indirect effect may be the incolporation of carcinogenic and potentially mutagenic or teratogenic chemicals into lower food chain organisms, such as the plankton, and subsequent ingestion by higher trophic forms. Though aduil fish are usually capable of avoiding spilled floating oil, other life stages such as eggs and larvae are more susceptible. Because the estuaries are spawning and nursery grounds for many species, an oil spill could cause serious damage to future commercial and noncommercial stocks. Other impacts include sewage inputs, pesticides (Nimmo et al. 1971) and pulp mill effluent. 7.2.9 Subtldal Soft Bottoms a. Introductlon. Subtidal unconsolidated bottom environments (e.g., mud and sand) make up the most extensive habaat area in the Panhandle estuarine system, approximately 75% of the total submerged bottom area. In many ways, they are the least understood (e.g., in terms of governing processes) and most difficutl to study of all the habitats. Problems arise from (1) limited access to the habitat for direct Obse~ation of and experimentation on processes important to the system and (2) the commonly badvisibility (high turbidity) oftenencountered. Except in the extremely shallow areas, field work often requires SCUBA gear. A cursory inspection of the sediment surface gives an impression of a homogeneous, desert-like habitat without much physical structure (e.g., vegetation or rocks) and with few organisms. Upon closer investigation, however, a myriadof small burrowopenings andprojectingtubescan be observed. The overwhelming majority of organisms in this habitat live withinthe substrate (infauna), concealed from view. This habitat is three dimensional, and vertical (depth into the sediment) distances are important, as opposed to the two dimensionality of hard substrate environments. Microscopic inspection of a scoop of sand or mud reveals hundreds to thousands of organisms, most of which are important prey items in the ecosystem. Abiotic factors play an important role in determining the distribution of the benthos, especially In the upper regions of the estuaries near the river mouths (Livingston et al. 1976). Sediment characteristics, such as grain size andorganiccontent, and physical factors, such as salinity and temperature, are most important. Grain size appears to be the single most critical factor because many organisms have specific requirements for feeding and tube building (e.g., White 1971). Deposit feeders (i.e., animals that ingest sediment particles) usually dominate in fine-grained muddy sediments because of the increased availability of detrital material and microorganisms as food. Suspension feeders require contact with the sediment-water interface to feed and are usually present in more stable sedimentary environments where there is less sediment movement and suspended material to clog their feeding structures.
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7. Estuarlne, Saltwater Wetl and, and Marine Habltats Of all the water bodies in the Panhandle, the eastern halt of St. George Sound, Apalachicola Bay, and Alligator Harbor have been the most intensively studied, primarily because of the Florida State University Marine Laboratory facilities (e.g., SCUBA equipment, boats, and eager graduate students) at Turkey Point. b. Physlcal description. Unvegetated softbottomenvironments in the Panhandle are generally made up of qualtz sand and fine silt. Ray feedingpits, crabpits, horseshoecrabtrails, gastropod trails, and sand dollar trails, and entempneust (i.e., acorn worm) fecal mounds andcones are prominent microtopographic features on the surface. After rough weather, wave-formed ripple marks up to 3 cm tall may be present for a few days. d. Faunal composltlon. The organisms in softbottom communities can be categorized into various functional groups based upon life positions (i.e., infaunal or epifaunal) and feeding (ortrophic) group (i.e., deposit feeder, suspension feeder, carnivore, etc.). lnfaunal organisms include most polychaete, bivalve, amphipod, and isopod species. Typical epifaunal organisms are asteroids (e.g., starfishAstropecten articulatus and Luidia clathrata), echinoids (e.g., sand dollars-Mellita quinquiesperforata and Encope mitchellf), decapods (e.g., Libinia spp.), various gastropods, benthic fish, and skates and rays (Table 33). Trophic group classification is less taxon specific, but requires natural history information on the specificorganism. Such information is too detailed for inclusion in this document. Ray (1986) has compiled heavily referenced life histories for mst of the polychaete species in the Panhandle. C. Dlstrlbution. Because Of the reduced light The most abundant metazoan constituents of penetration and the siltation from the large amounts soft-bottom habitats are the meiofaunal nematodes of sediments deposited by rivers, the majority Of the and harpacticoid copepods (Table 34). In terms of bottom area of Panhandle bays and estuaries is biomass, however, polychaetes, mollusks, and unvegetated. Unvegetatedsoft bottomscovermore macrocrustaceans dominate (Table 35). These than 75% of the total bottom area in the Panhandle. groups are especially abundant in higher salinity Table 33. Demenal tlsh, skates, and rays commonly encountered In Panhandle soft-bottom habitats (Hoese and Moore 1977). Grouo Saecles Common name Fish Paralichthys albigutta Paralichthys lethostigma Prionotus scifulus Synodus foetens Skates and Rays Aetobates narinari Dasyatis americana Dasyatis sabina Dasyatis say; Gymnura micrura Narcine brasiliensis Prisfis pectinata Raja eglanteria Raja texana Rhinobatus lentiginosus Gulf flounder Southern flounder Leopard sea robin Lizardfish Spotted eagle ray Southern stingray Atlantic stingray Bluntnose stingray Smooth butterfly ray Lesser electric ray Smalltooth sawiish Clearnose skate Roundel skate Atlantic guitarfish Rh~noptera bonasus Cownose ray
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Panhandle Ecological Characterlzatlon Table 34. Abundant or common benthlc melofauna In Panhandle soft-bottom habitats (Reldenauer and Thistle 1981 ; Sherman et al. 1983; D. Thistle, Florida State Unlverslty, Tallahassee, unpublished data; Carman 1984). Group Species I Group Species Nematoda Chromadorella sp. Chromaspirina sp. Desmodora sp. Innowonema spp. Metachromadora (Metachromadoroides) spp. Microlaimus spp. Monoposthia sp. Sabatieria sp. Theristus spp. Viscosia brachylaimoides Copepoda Harpacticoida Amphiascus spp. Ectinosoma spp. Enhydrosoma littorale Halectinosoma spp. Leptastacus cf. aberranus Mesochra cf. pygmaea Pseudobradya cf. exilis Robertgurneya rostrata Zausodes areniwlus Table 35. Abundant or common benthlc macroinvertebrates in Panhandle soft-bottom habitats (Hartman 1951, Carpenter 1956, Trott 1960, Grltfin 1983, Reidenauer 1986). Group Species I Species Polychaetes Aricidea cerrotii Aricidea taylori Axiothella mucosa Capitella capitata Eteone heteropoda Haploscolopbs fragilis Haploswloplos robostus Heteromastus filiformis Laeonereis culveri Mediomastus califomiensis Paraonis fulgens Paraprionospio pinnata Prionospio heterobranchia Prionospio pygmaea Spio benedictii Polychaetes (continued) C~staceans Mollusks Cephalochordata Echinodermata Swlolepsis squamata Typosyllis sp. Acanthohaustarius spp. (amphipod) Apanthura magnifica (isopod) Corophium louisiana (amphipod) Kalliapseudes bahamensis (tanaid) Anodontia alba Tellina spp. Branchiostoma floridae Astropecten arf;culatus Luidia clathrata areas of the estuaries (Wintemitz 1936, Yentsch nities are characterized by a high degree of spatial 1953, Wass 1955, Trott 1960. Borror 1961. Griffin variability at nearly all scales (centimeters. meters, 1983). In the lower salinity regions near river and kilometers), yet individual populations are usumouths, insect larvae and oligochaete worms beally highly persistent and, in many instances, seacome more important. Soft-bottom benthic commusonal. Also included as part of this habitat are
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7. Estuarine, Saltwater Wetland, and Marlne Habitats demersal fish (e.g., flounders), skates, and rays, that spend a majority oftheir life and feed on the bottom. Most infaunal members of the son-bottom community are concentrated within the upper few centimeters of the sediment surface. This is the depth of theaerobiczone. The aerobiczonecan be extended deeper within the sediment by animal tubes and burrows, which bring oxygenated waterto otherwise anoxic sediments. Meiofaunal organisms are concentrated along these structures and are therefore capable of existing deeper within the sediment. The total number of species and individual organisms observed at any particular site is afunction of many different factors. Among these are the time of year that samples are taken, the sampling gear used, and the physical conditions (e.g., tide stage, weather, and time of day) at the time of sampling. bottom habitats in the Panhandle, which can undergo periods of extremely high population densities, with 200-800 individuals/m2 (Salsman and Tolbert 1965, Reidenauer, in prep. a) (Figure 76). These periods of high density are short-lived and most times densities are around 20/m2. The high densities are apparently the result of appropriate conditions for the successful recruitment of juveniles. Many benthic species, such as Mellita, have planktonic larval forms that require specific physical conditions and low predator densities for successful recruitment. e. Recreatlonally and commercially Important specles. (1) Southern flounder (Paralichthys lethostigma). The southern flounder migrates and spawns offshore in the fall and winter (Nall 1979). Larvae eventually move inshore into the estuaries. Juveniles (1 0-1 5 cm) are abundant in shallow son sediments during the late spring and early summer Many organisms demonstrate not only season(Reidenauer, personalobservation). Juvenilesfeed al differences in abundance, but year-to-year variaon a variety of polychaetes and crustaceans. Adults tions that are not, at present, readily predictable feed almost exclusively on fish andcrustaceans. An (Figure75). Forexarnple,thefne-slottedsanddoliar 11-~nch minimum size is placed by the State of is a common visible member of the subtidal softFlorida on landed flounders. Figure 75. Seasonal variation of the spionld polychaete Prlonosplopygmaea In a St. George Sound subtidal soft-bottom habitat (Reidenauer 1986).
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Panhandle Ecological Characterization Figure 76. Varlatlon In a flve-slotted sand dollar (Melllta qulnqulespefforata) population from St. George Sound (Reldenauer 1986). W m IS I 3 = 10 (2) Northern quahog (Mercenaria mercenaria). and sunray Venus clams (Macrocallista nimbosa). Both species are found in the estuaries and nearshore coastal waters of the Panhandle from the mean high tide level to 15 m depth with highest abundances on shallow flats (Akin and Humm 1959, Menzel1961. Haines 1975). Hawesting is limited in the Panhandle although maricultural and commercial attempts have been made (Joyce 1970, Menzel et al. 1976). 5, ,/'~,I+'I~~*~,+,~ I:, ,!+!!I,,! f. Trophlc dynamics and Interactions. The majorityof benthic species are preyfor highertrophic organisms. The meiofauna, especially harpacticoid copepods, are important prey forjuvenilefishessuch as pinfish (Laaodon rhomboides) and southern flounder. Polychaetes and bivalves are important in the diet of many fish and crabs. JFMAMJJASONDJFMAMJJASONDJFMAMJJA In general predation appears to be an important, if not the single most irnportant, process governing soft-bottom benthiccommunity dynamics (Mahoney and Livingston 1982). Historically, competitive interactions have been diificultto demonstrate inthe softbottom environment given the hydrodynamic problems of predator exclusion pens (i.e., increased siltation due to current baffling) and the nearly invisible nature of the benthic inhabitants (i.e., hidden in the sediment or of a small size). In most regions, population densities are usually too low for competition to be an important process. Spatial competition (as in hard substrate communities) is rare in soft sediments, and competition for food is extremely difficult to demonstrate conclusively. Mutualism is present in a variety of forms in the soft-bottom environment. The pea crab, Dissodactylus spp., (approximately 6 mm carapace width) lives among the spines of the five-slotted sand dollar and apparently selectsfood particles as the echinoid burrowsthroughthesediment. Inaddition,otherpea crabs (Family Pinnotheridae), use the burrows of various burrowing shrimp, such as Callianassa and Upogebia, as shelter. g. Natural Impacts. The soft-bottom subtidal environment appears more resilient to natural impacts than most marine habitats. A primary reason may be the planktonic larval dtspersal characteristic of many of its residents. Furthermore, many benthic
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7. Eatuarlne, Saltwater Wetland, and Marlne Habltats species traditionally categorized as sessile organisms are now known to disperse some distances as adults, especially at night, throughthe watercolumn. Natural disturbances such as ray feeding pHs and enteropneust fecal mounds have been intensively examined in St. George Sound (Thistle 1980, Reidenauer and Thistle 1981, Griffin 1983, Sherman et al. 1983). Generally, the benthic communities, both meiofaunal and macrofaunal, initially decrease in abundance immediately after the disturbance but return to predisturbance levels within hours or a few days. Apparently these types of disturbances are either not on spatial scales large enough to produce long-lasting effects, orthecommunity as awhole has adapted to them. Natural disturbances such as sand-dollar burrowing are apparently a source of mortality for newly settled polychaete, especially spionids (Reidenauer in prep. b). The most importan1 effect of disturbance, therefore, may be on juvenile or larval members of the community and not on adult members that can mre easily disperse. Storm-induced waves often form ripple marks on the estuarine floor. In investigations performed outside the Panhandle, it was found that the trougns of the ripple field tend to collect fine particles and therefore food, which is attractive for a variety of organisms such as meiofaunal nematodes and harpacticoid copepods. Storms in general appear to disrupt the distribution of benthic organisms temporarily. Duncan (1977) has reported on the effects of stormwater runoff on benthic communities in the Panhandle. An influx of silt or fine-grained sediment may decrease the number of sedentaly or sessile members of a benthic community through suffocation. On the other hand, small burrowing depositfeeding forms, such as capitellid and opheliid polychaetes, usually increase in abundance because of their planktonic larval stage. h. Human Impacts. The effects of human activity on soft-bottom communities has not been extensively studied within the Panhandle. Some of the studies that have been done were not well designed or executed, so the results are not reliable. Problems have included samples taken without proper controls or without regard to season and use of improper sieve sizes to ensure that the majority of the community was sampled. The most important human influences on the soft-bottom communities are dredging, boat traffic, petroleum pollution, and toxic substances such as pesticides. Dredging and the offshore collection of sediment for beach renourishment have been reported to have minimal but long-term effects on the benthic community (Water and Air Research, Inc. 1975, Saloman et al. 1982a). Apparently, natural seasonal variations are so great that short-term isolated perturbations are not permanently damaging. However, the evidence is limited and the problem is one that should be more thoroughly addressedintermsof implicationsforthe highertrophic grouporganisms. Disturbancesfrom boattraffic are not documented for the Panhandle and probably represent only localized impacts. Byrne (1976) has reported on the effects of petroleum pollution on larvae of the quahog clam (Mercenaria sp.) found in Alligator Harbor. The effectsof various pesticides on the benthic community have been examined by Duke et al. (1970), Hansen an6 Wilson (1970), Livingston et al. (1978), Tagatz and lver (1981), and Winger et al. (1984). 7.2.10 Seagrass Beds a. Introducllon. Seagrasses represent one of the most important habitats in the nearshore coastal zones of Florida Of the approximately 12,000 km2 of seagrass present in the Gulf of Mexico over9,lOO km2 Ile in Florida gulf coast waters (Iverson and Bittaker 1986). Seagrasses are marine angiosperms that possess all the structuresof their terrestrial counterparts (i.e., a root system, a vascular system, and vegetative and sexual reproduction). Seagrasses are obligate halophytes, living fully submerged andcarrying out their entire life cycle in seawater. Seagrass meadows are highly productive and rich in organisms. Total productivity of dense beds (which may consist of more than 4,000 individual plant shoots per square meter) including the plants themselves and the attached flora can reach 20 g C/mZ per day, making them more productive on a per unit basis than eithertropical coral reef systems (1 0 g C/m2per day) orthe upwelling regions off Pew (1 1 g C/m2 per day).
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Panhandle Ecalagical Characterization The physical structure provided by seagrass blades and rhizomes increases available habitat surface area for surrounding organisms as much as 15-20 times compared to unvegetated bottoms. In addition, it offers refuge from predators to many large juvenile populations of commercially important species of invertebrates and fish. For example, the commercial yield of shrimp in an estuary is directly related to the amount of seagrass habitat present (Figure 77). The combination of shelter and food makes seagrass meadows one of the richest and most critically important nursery grounds in Florida Panhandle coastal waters. Two types of food webs are associated with seagrass communities: (1) a "grazing" food chain component comprised of herbivores that feed on living plants (both the seagrass blade itseil and the associated algae) and their predators; and (2) a detrital food chain component comprised of herbivores that feed on dead material, togetherwith their associated predators. Only a few species of animals in the Panhandle graze directly on living seagrasses (e.g., urchins, fishes, and some ducks and geese at low tide) and only a small fraction of the energy and nutrients in a seagrass bed is channeled through these herbivores (Thayer et al. 1984). For the vast majority of the herbivores (e.g.. gastropods) in the seagrass ecosystem, the epiphytic algae constitute their primary food source (Kining et al. 1984). Seagrasses have many critical functional roles in the coastal environment. Some of the most important include: (1) serving as a sediment trap and stabilizer of bottom sediments; (2) providing primary productivity to the sea; (3) serving as a direct food source for herbivorous organisms; (4) serving as a source of large quantities of detritus and dissolved organic matter; (5) providing an attachment substrate for epiphytic algae that is a primary food source for many seagrass herbivores; (6) providing a refuge from predators for many juvenile forms of fish and invertebrates, including economically important species; (7) providing a habitat for a certain assemblage of invertebrate species that burrow orgrow attached to leaves and thatwould otherwise be uncommon or absent, and; (8) possibly serving as a major link in the main biochemical cycles of coastal areas. 1 070 .-" m lo6 ,; k 5 Z lo5. U) 0 al a104 Like terrestrial grasses, seagrasses form recog nizabte biological and physical entitiesthat are ollen termed meadows. Like many terrestrial systems, the f seagrass meadow is defined by a visible boundary gradingfrom an unvegetatedtovegetated substrate. In the Panhandle, meadows vary in size from small isolated patchesof plants <1 m across, to continuous distributions of grass over many square kilometers. Meadows can be composed of a single species (usually turlle grass-Jhalassia testudinum) or multiple species (Thalassia, shoal grass (Halodule), .0. and manatee grass (Syringodium) are commonly found together). Although still a conspicuous feature of the shall&? l& l;!? 10610w-watercoastal areas of the Panhandle, seagrass coverage appears to have suffered significant deVegetated Estuary 1 ha 1 clines in many of the major bays over the last few decades. The primary reason appears to be the Figure 77. Yield of penaeid shrimp and vegetaincreased impacts (e.g., from dredging and pollution coverage In an estuary (after Turner 1977). tion) of a growing coastal population. 21 2
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7. Estuarine, Saltwater Wetland, and Marlne Habltats b. Seagrass species present. For this report, Ruppia rnartima is not considered a true seagrass because it is not an obligate halophile and can grow in fresh water. It is found in the brackish vegetation habitat. Of the approximately 50 worldwide species of seagrass, 5occur in the Panhandle region (Figure 78 shows the four most common): Thalassiatestudinum, turtlegrass, isthe largest, most robust of the seagrasses. Its ribbon-like leaves are 4 to 12 mm wide and 10 to 35 cm long with rounded tips (Figure 79). Two to five leaves are commonly present per shoot. Rhizomes, or roots, are found 2-5 cm deep in the sediment. Undisturbed. Thalassia is capable of forming extensive meadows. It grows at a minimum water depth of 0.5 m and rarely grows in water deeper than 11-12 m (Moore 1963). Bittaker and lverson (1976) and Bell (1979) reportedonthe productivity of Thalassiain St. George Sound, which averaged 500 mg Clm2 per day and was linearly proportional to the light energy. Syringodium tilitorme, manatee grass, has leaves that are circular in cross-section and typically has 2 to 4 leaves per shoot. Leaf diameters range from 1.0 to 1.5 mm. Blade length is highly variable but can exceed 50 cm. The rhizome system is less robust than that of Thalassia and not as deeply rooted. It is commonly found mixed with other seagrasses or in small, dense monospecific patches. It rarely forms extensive meadows like those of Thalassia. Halodule wrightii (Diplanthera wrighti~). shoal grass, is extremely important as an early colonizer of disturbed areas where Thalassia and Syringodium are excluded. It commonly grows in water either too shallow or too deep for other species. The leaves are flat, typically 1 to 3 mm wide, 10 to 20 cm long, and arise from erect shoots. The tips of the leaves have two to three small points. It is the most tolerant of all seagrasses to variations in temperature and salinity. Halophila engelmannii is a shade-loving species. It is an initial colonizerof newly available substrate and isextremely pollution tolerant. It is almost never present in monospecific beds, except in areas offshore. In the Gulf of Mexiw it grows up to 30 rn deep. Halophila decipiens is known from isolated areas of the Panhandle region at least 6-7 m deep in the open gulf off Alligator Point and Pensacola (Humm 1956). It is a tropical species which may be limited to deeper water in the Panhandle where temperatures are not as extreme as those in the shallows. Of the five species, the first three are the most commonly encountered in the Panhandle. A diagramof distributional ranges (i.e., salinity anddepth) for 4 species is given in Figure 80. c. Seasonallty. Seagrasses in the Panhandle are perennial and reach a peak in biomass in the summer. New short-shoot production occurs only during the spring and summer. Thalassia leaf biomass in St. George Sound and St. Joseph Bay reaches a seasonal maximum during August (Iverson and Bittaker 1986). Seagrasses grow at a very reduced rate during the winter months. Each winter the seagrass blades of all species die back to within several centimeters of the sediment-water interface (Iverson and Bittaker 1986). d. Specles succession. Seagrass beds in the Panhandlego through anorderly process of succession, if left undisturbed. See Zieman (1982) for a discu~~lon of the successional theory of seagrasses. Since there are only a few species present, the sequence is fairly simple (Figures 81 and 82). Algae are usually the first to colonize a disturbedarea. Theirprimaiycontribution tothesuccessional process isthe accumulation and binding of sedimentary particles. The pioneer grass species is Halodule, which colonizes either by seed or rapid vegetative branching. It further stabilizes and protects the substrate surface. Syringodiurn appears next and as development continues, Thalassia becomes established. The time required for the recovery of a damaged bed depends upon the magnitude of the initial disturbance and on local wave and current intensity. However, even small patches take 2 to 5 years to recolonize (Zleman 1982). If the entire bed is removed, recovery may never occur since the source of potential colonuers is gone. Seagrass bed morphology is believed to denote maturity and successional stages (Hartog 1970,
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Panhandle Ecological Characterization Halophila engelmannii Halodule wright ii Syringodium f iliforme Thalassia testudinum Figure 78. Four common seagrass specles present In Panhandle waters (after Zieman 1982). 21 4
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7. Estuarine, Saltwater Wetland, and Marine Habitats AVERAGE LEAF WIDTH 1 mml I LEAF -----RHIZOME MERISTEM BRANCH OR SHORT SHOO 7 9 6 8 9 RHIZOME' DISTANCE BETWEEN BRANCHES lcmi Flgure79. Diagram of a typical Thalassiashoot showing oldest leaves to left and new growth on right (after zleman 1982). Winter 1978). A pure Halodule bed is considered pioneer. A nearly equal mix of all three species is considered intermediate in development. Corefringe morphology with a central core of intermixed Thalassia and Syringodium surrounded by a fringe of Halodule indicates mature beds. e. Dlstrlbutlon. The most recent estimate of total coverage of seagrass beds in the Panhandle is approximately 637 km2 (Table 36). The data that exist for the 1970's and 1980's show an accelerated decline of grassbeds in many bays, especially in the Pensacola estuary system where Escambia Bay grassbeds are nearly entirely absent. Generally, there is no documentation of areal extent priorto the last few decades, so it is not known how much has been lost. The following discussion documents the most recent account of seagrassdistributionineach majorbay system inthe Panhandle and discusses changes in the system if such information was available at the time of writing. (I) Ochlockonee Bay. Only a few scattered patches containing some Thalassia have been reported near the opening of the bay into Apalachee Bay (Phillips 1960, McNulty et al. 1972). (2) Alligator Harbor and St. George Sound. Alligator Harbor has large beds in its eastern one-thlrd, along the northern shore, and on Bay Mouth Bar at the entrance of the harbor. There are extensive, continuous beds along the northern shores of St. George Sound. These beds are concentrated in the eastern one-half of the Sound. (3) Apalachicola Bay System (i.e., East Bay, Apalachicoia Bay, and St. Vincent Sound). The
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Panhandle Ecological Characterization MHHW MLHW A(.. fl HALOPH ILA THALASSIA RUPPIA HALODULE SHORE MLLW 1( HALOPHILA v HALODULE t RUPPlA -1 b THALASSIA SYRINGODIUM THALASSIA SYRINGODIUM HALODULE seagrass distribution in the Apalachicola Bay Syswater in upper East Bay, inside St. George Island in tem is not very extensive given the large area of the Apalachicola Bay, and in western St. George Sound estuary (30,480 ha). High turbidity and sedimenta(Livingston 1984). Halodule and Syringodium tion from river input decrease light levels and prodominate most areas. Grassbeds are nearly absent duce an unsuitable substrate for seagrass growth in from St. Vincent Sound but somesmall isolated beds most areas. Seagrasses are primarily concentrated do exist (H. Bittaker, Florida Department of Comalong the fringes of the estuary in less than 1 m of munity Affairs, Tallahassee; pers. comm.). *.......I ABUNDANT SPARSE ............................... I?, (........ 1 ABUNDANT SPARSE ? ............................... ........ ABUNDANT I RUPPlA q ABUNDANT .1 1 1 I 40 35 30 25 20 15 10 5 0 SALINITYlppt] Figure 80. Diagram showing typical depth distributions of three seagrass species and a common brackish species Ruppiamaritima(after McNuity et ai. 1972). MHHW = mean higher high water; MLHW = mean lower high water; MHLW = mean higher low water; and MLLW = mean lower low water.
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7. Estuarine, Saltwater Wetland, and Marine Habitats ECOSYSTEM DEVELOPMENT SANDY SUBSTRATE RHz:p HALODULE SYRINGODIUM ~MS~A MUDDY / SUBSTRATE STABLE ENVIRONMENTAL CONDITION -1.1 DISTURBANCE Figure 81. Ecosystem development In seagrasses. Without disturbance a Thalassla climax Is reached (modified from Zleman 1982). -Dominant Water Flow RELATIVE BIOMASS Above Sediment Below Sediment o lo g/m2 Figure 82. Idealized sequence of seagrass recolonization and growth in a large disturbance (after Zieman 1982).
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Panhandle Ecological Characterization Table 36. Surface area of major water bodies and most recent seagrass distribution estimates for the Panhandle water bodies (a = McNulty et al. 1972, b = Savastano et al. 1984). Water body Bottom area (ha) Grassbed area (ha) Source Alligator Harbor 1,637 261 a St. George Sound 30,762 3,392 a East Bay 3,981 1,434 a Apalachicola Bay 20,960 1,125 a St. Vincent Sound 5,540 10 a St. Joseph Bay 17,755 2,560 b St. Andrew Sound 1,906 151 a East Bay (St. Andrew) 7,557 464 a St. Andrew Bay 10,615 1,029 a West Bay 7,118 626 a North Bay 2,704 41 7 a Choctawhatchee Bay 34,949 1,252 a Santa Rosa Sound 9,947 1,897 a East Bay (Pensacola) 14,906 0 a Escambia Bay 9,754 0 a Pensacola Bay 16,435 627 a (4) St. Joseph Bay (Figure 83). The seagrasses nearly circumscribe the entire inner shore of the bay. The figures of McNulty et al. (1972) show that-it contains the most seagrass coverage (on a per area basis) of any single bay in the Panhandle. A more recent aerial survey and reported local observations (Savastano et al. 1984) reveal that seagrass distribution has remained unchanged from 1972-78 with apparent stability of community species types. (5) St. Andrew Bay System (includes St. Andrew Sound, East Bay, St. Andrew Bay, West Bay, and North Bay). In total acreage this system contains the largest seagrass stock in the Panhandle (McNulty et al. 1972). Unfortunately, there have been no published reports since 1972 giving precise seagrass areas in the system, and therefore it is impossible to document any change that may have recently occurred in the bay. Seagrass composition has been noted at certain stations in a more recent study (Grady 1981). Halodule was the dominant species at intertidal stations on the shore of the East Arm of St. Andrew Bay. The north shore of the East Arm was nearly devoid of seagrasses, except for Halodule near Pitt Bayou. Halodulewas predominant on the north shoreof the West Arm, while afew stations dominated by Thalassia were found on the south shore. Since this system is offshore of the fastgrowing Panama City area, it would be prudent to take an inventory as soon as possible in order to assess current damage and provide a base for the future assessment of impact on the system. (6) Choctawhatchee Bay. The vegetation of the bay was studied most recently by Burch (1983a), who documented changes in coverage overthe past 30 years. The only seagrass species present is Halodule wrightii. Beds are concentrated in the western section of the bay (Okaloosa County) and grow primarily at depths of 1 to 2 m and in areas of abrupt depth change from 2 to 5 m. Six major areas support significant seagrass populations (i.e., bottom coverage greater than 40%): Hogtown Bayou, Moreno Point from the Okaloosa-Walton County line to Joe's Bayou, East Pass, the Santa Rosa Sound entrance, Black Point, and, White Point. Five major areas contain beds with less than 40% bottom coverage: Far Mile Point, east of the Okaloosa-Walton
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7. Estuarine, Saltwater Wetland, and Marlne Habltats km. At some point eastward toward Tom King Table 37. Domlnant eplphytlc organisms (flora Bayou, Halodule replaced Thalassia as the domiand fauna) that grow on the seagrass blades nant species. From 1949-66, seagrass coverage (Dennis 1981, K. Sherman pers. comm.). declined by approximately 50/.. From 196~74, losses accelerated, and in 1974 no significant stands Graup were left. Species The Santa Rosa Sound was most recently surMicroalgae veyed by Winter (1978) and Williams (1981). Using Macroalaae divers, winter Su~e~ed beds between theaewage treatment plant and Range Point on Santa Rosa Island along five transects at 61 0,457,304, and 153 m from shore and along the 1 m depth contour. A total of 26.1 ha of viable seagrasses were located. Three species, Thalassia testudinum, Syringodium filiforme, and Halodule wrightii, were present. Near development on the shore, seagrass coverage was severely reduced and only immature beds were identified This was interpreted as resulting from disturbances caused by heavy boat traffic and by a fill project that may have covered over some of the beds. Turbidity was postulated as a primary cause of the decline because deeper beds were dead whereasdeep bedsoff Fort Pickensand the National Seashore, where there is nodevelopment, were still present and viable. A further increase in water turbidity was identified as the most serious potential impact to the future success of seagrasses in the Sound (Winter 1978). f. Associated flora and fauna. The classification of the biotic components of the seagrass meadow habitat follows Kikuchi (1980). In this scheme, the flora and fauna are divided into the following three categories on the basis of the microhabitat structure and the mode of existence of the organisms. (1) epiphytic organisms that grow on the seagrass blades (Table 37) including: (a) microand macroalgae and the microand meiofauna associated with these algae. (b) sessile fauna attached to the leaves. (c) mobile fauna crawling on the leaves. (d) swimming fauna which rest on the leaves. (2) highly mobilefaunathat swimwithinandover the leaf canopy (Table 38)--decapod crustaceans and fishes that may be either diurnal or seasonal transients or permanent residents. Nematoda Chromadora nudicapitata Epsilonema sp. Sphiliphera paradoxa Syringolaimus striatocaudatus Viscosia macramphidia Copepoda Altheotha spp. Ectinosoma spp. ldomene spp. Laurinia spp. Metis spp. Parategastes spp. Pholetiscus spp. Porcellidium spp. Tegastes spp. Zaus spp. Polychaeta Serpulidae Porifera Haliclona permollis Halicometes perastra Mycate cecilia (3) epibenthic and infaunal invertebrates that dwell on orwithin the sediments (Table 39). Many of these species may display nocturnal vertical migration patterns between the sediment and the blades of the seagrasses. Rather than being endemic to the seagrass habitat, they appearto be an extensionofthe benthiccommunity that livesonand in the adjacent unvegetated substrate. The functional categories are all intimately linked to the seagrass and exhibit shifts in abundance in responsetochanges in seagrassdensity as well as to seasonal fluctuations in environmental parameters. Thus, within any specific meadow, there is considerable temporal variation in the composition and density of associated flora and fauna.
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Panhandle Ecologlcal Characterlzatlon Table 38. Domlnant moblle fauna wlthln the seagrass leaf canopy (Abele 1970, Eldemlller 1972, Sherldan and Llvlngston 1983). Group Species name Decapoda Alpheus heterochaelis Callinectes sapidus Clibanarius vittatus Eoialtus dilatatus Table 39. Domlnant eplbenthic and lnfaunal lnvenebrates that Ilve on or wlthlnlhe sediments of seagrass meadows (Shier 1965, Kritzler 1971, Osborne 1979, Saloman et al. 1982b, Sherman, personal communlcatlon). Eurypanopeus depressus I Hippolyte pleuracantha Hippolyte zostericola Libinia sp. Neopanope packardii Neopanope texana texana Pagurus bonairensis Pagurus longicarpus Palaemon floridanus Palaemonetes intermedius Palaemonetes pugio Palaemonetes vulgaris Pelia mutica Penaeus duorarum Tozeuma cardinense Group Specles name Nematoda Chromaspirinic spp. Theristus soo. Upogebia affinis Tanaidacea Hargeria rapax lsopoda Lironeca ovalis Fish Bairdielia chrysoura Cynoscion nebulosus Lagodon rhomboides Orthopristis chrymptera There are also horizontal variations wthin the structure of the seagrass meadow. Siltclay content, organic matter, and nitrogen pools are lowest out'olychaeta Aricidea taylori Axiothella mucosa Ceratonereis mirabilis EXOQO~~ dispar Heteromastus filiformis Hobsonia florida Neanthes acuminata Nereis pelagica Onuphis nebulosa Platynereis dumerilii Scyphoproctus platyproctus Spio Micornis Strebbsoma hartmanae Syliis cornuta Mollusca Caecum floridanurn Cardita floridana Crepidula maculata Mitrella lunata Modiolus americanus Modiolus demissus Neritina reclivata Ostrea frons C~stacea Ampelisca vadorum Ampelisca spp. Cymadusa compta Cymadusa sp. Lysianmopsis sp. side the meadowsand ~ncrease tn magnitude toward HydroldS thecenterolthe bed. Shoot densityandthe standing crop of leaves and of root-rhizomes also increase from the edge to the inside. The faunal community phytes-macroalgae anached to the blade; perimay reflect this edge to center gradient, but existing phyton4icroalgae such as diatoms, algal spore. data are inadequate to prove that hypothesis. lings, and bacteria that coat the blade) provide food for other organisms through (1) direct herbivory, (2) g. Trophlc dynamlcs and InteraCtlOnS. detrital food webs within the beds, and (3) exported Seagrasses with their attached flora (i.e., epimaterial--macroplant materialordetritus-(Zieman
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7. Estuarine, Saltwater Wetland, and Marine Habitats 1982). The primary energy pathway appears to be direct herbivory on the algal epiphytes rather than the detriial food web (Kitting et a1.1984). However, detritus is still a major energy pathway. Grazing on the more refractory seagrass blades is not extremely important and is limited to only a few organisms (Montfrans et al. 1984). Annual epiphyte production can approach 20% of the seagrass production. Several factors control seagrass epiphytic communities (Figure 85). Epiphytic grazers include a wide diversity of organisms: gastropods (the most prominent), amphipods, isopods, decapods, echinoderms, and fish. Some organisms (e.g., sea urchins and fish) remove large portions of the seagrass blade along with the attached algal epiphytes. Periphyton grazers, in most cases, remove only loosely adhered diatoms and algal sporelings, but leave the grass blade intact. The organisms that live among the epiphytic algae may be an important food source (Alvis 1971). Crustaceans and nematodes are the dominant forms. A number of fish feed on the infauna living in the sediment in the grassbed. Stingrays actually excavate the sediment, creating pits during feeding. Rays have been noted to concentrate their feeding along the seagrass meadows fringe where the rhizome mat is not as heavily developed (Reidenauer, pers. observ.). Many fish feed on epifaunal organisms as juveniles and are piscivores as adults, for example the bonnethead shark (Sphyrna tiburo) and the lizardfish (Synodus foetens). Besides predation and grazing, other interactions among seagrass and its associated community Figure 85. Schematic view showing the numerous seagrass epiphyte interactions that occur in a seagrass bed and the important physical factors affecting the Interactlons (after Montfrans et al. 1984). 223
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Panhandle Ecological Characterlzatlon have been examined. The epiphyte-seagrass association is a complex one (Figure 85). Epiphytes may benefit seagrass in a number of ways: reduction of desiccation during low water through entrapment and retention of moisture, protection against dam age from ultraviolet radiation, and selective removal of the highly epiphytized and senescent leaf tips, which causes minimal damage tothe plant itseii and increases light penetration through the seagrass canopy. The distal portions of the blades are the oldest and generally most heavily epiphytized. Epiphytes may also damage seagrasses by competing for similar wavelenglhs of light, shading, suppressing carbon (HCO;) and phosphorus (PO,) assimilation, and causing diurnal changes in pH and oxygen content of the surrounding water limiting plant growth and killing seagrass-associated fauna. In addition, light attenuation by epiphytes is thought to cause premature senescence in seagrasses. The infaunal communities, especially the meiofauna community, in seagrass beds have been examined (e.g., Ruddell 1976): harpacticoid copepod abundances are significantly higher in the sediment surrounding isolated seagrass blades (Thistle et al. 1984). The physical structure of the blade may offer a refuge from fish predation (Dennis 1981). In addition, sediment microbe abundance around the blade is significantly higher than in unvegetated sand, possibly attracting meiofauna to the enriched food source. h. Commerclally Important specles. Scallops are common in and around seagrass beds in the Panhandle. Two scallopspeciesoccur in the region. bay scallops (Argopecten irradans) and calico scallops (A. gibbus) (Sastry 1961). The bay scallop isthe most common species associated with nearshore Panhandle seagrass beds. St. Joseph Bay is a popular scalloping area in the region because of Its lush seagrass beds and clear waters. Scallops spawn in the fall in north Florida. The larvae are planHonic for a few weeks and then anach to seagrass bladesfor several weeks before metamorphosis into adults. Maximum life span is about 2 years. Many die after one spawning season (12-14 months old). Adults are finer feeders on phyfoplankton, primarily diatoms. There is no closed season on bay scallops for public harvest. Commerclally, they may not be harvested before August 1 because this is when maximum size is attained. Blue crabs are also abundant in Panhandle seagrass beds. Juvenile blue crabs are commonly found in shallow seagrass beds (Oesterling 1976). Adults are generally found in muddy sediments upto 35 m deep. Females migrate to higher salinity waters offshore to spawn. Juveniles migrate from offshore back into the estuaries. Blue crabs reach commercial size (7.7 cm carapace width) within 1-1.5 years and live upto3-4 years. Adunsfeedon live prey such as small fish, oysters, and clams. and they are alsoscavengers. There isnoclosed season on blue crabs in the Panhandle, but they must be 7.7 cm across the carapace and females must not be egg-bearing. I. Natural Impacts. Hurricanes and severe tropical storms are common along the Panhandle coast (seeChapter3). Seagrass bedscanwithstand hurricane force winds with little sedlment erosion and minimal damage (i.e.. primarily leaf damage), while adjacent unvegetated areas experience extensive erosion. Damage may occur, however, from indirect effects such as reduced photosynthesis caused by increased water turbidity and heavy sedimentation within the bed from the increased sediment load in the water column. All seagrass species have an upper and lower temperature tolerance (McMillan 1979) beyond which they may be destroyed. The levels vary with local populations. It appears that seagrasses form photosynthetic and phenological biotopes that are adapted to local temperature ranges and these, in tum, control the entire ecosystem. However, it is difficult to generalize about responses to temperature. Salinity fluctuations do not appear to have the extreme effects on seagrasses that temperature fluctuations may have, alhoughfhe species seem to have a range of salinity tolerances. j. Human Impacts. Dredging and filling prove the greatest threat to the seagrass ecosystem (Thayer et al. 1975, Zieman 1975, Phillips 1978). The plants themselves are physically removed and the entire biological, chemical, and physical structureof the ecosystem is changed. The extent of area
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7. Estuarine. Saltwater Wetland, and Marlne Habltats directly affected by dredging depends on the tidal range, current strength, and sediment texture in the area. The sediments stirred up by dredging bury plants away from the actual project, but more importantly they also drastically reduce plant density by effecting water clarity (Zieman 1982). Duringdredging, light penetration through the water column is reduced, and productivity and chlorophyll content of the grasses decreases. The reduction in seagrass density caused by suspended silt increases the erosion of the bottom sediments and further affects additional areas. The redox potential of seagrass sediments is also upset by dredging, which reverses the entire nutrient-flow mechanicsof the ecosystem. Fill produces four major impacts on seagrass meadows: (1) direct covering and smothering of the grass. (2) indirect covering of the grass by drifting sediment, (3) reduced light penetration because of an increase in waterturbidity, resulting in a reduction in orcessationof photosynthesis, and (4) damage by depletion of oxygen caused by BOD of the till materials. float over the beds. However, oil spills can inflict severe damage on grass beds. Direct contact with oil can cause mortality. Probably of greater longrange concern is damage caused whenoil-sediment particles that have conglomerated elsewhere accumulate as grass beds reduce current velocity and sediments settle out of the water column. A surface oil sheen can also reduce light penetration and indirectly affect seagrass beds. Laying pipe for oil can directly destroy beds. In areas of low energy, seagrasses are buried and smothered by mud cuttings andfluids and are affected indirectly by turbidity from suspended drilling effluents (John Thompson, Continental Shel Associates: pers. comm.). Pollution from toxins and heavy metals has not been implicated in the direct, major destruction of seagrass beds. Evidence exists that roots of seagrasses may accumulate metals such as zinc (Zieman 1982). Concentrated metals may be passed along the food chain through the seagrasses. In many shallowwater Panhandle environments (e.g., St. Joseph Bay and Santa Rosa Sound), the physical destruction of seagrass beds by boat proThere is evidence that even Small-scale drew pellers is easily observed, Thalassiabeds are espeing projects in areas may cause a cially affected since this species does not spread its perturbation On seagrass ecosystems (Zieman rhizome mat very rapidly. Propeller cuts can be very 1975). persistent features, lasting for 3 years or more Attempts have been made to revegetate dredge (Zieman 1976). If the leaves of Thalassia, for exspoil areas with seagrass, especially with Halodule ample, are slightly damaged rapid regrowth will be wr@htj/plugs in St, Joseph Bay (Phillips et al, ,978). unlikel~' Rhizome growth is extremely 'low and if The projects have not beenvery successful because regrowth may never Trawling by of physical factors (i.e., cold temperatures and fishermen can tear up grassbeds. storms) that could not be predicted or controlled. More intensive studies should be conducted on Effluent discharge (particularly nitrogen and seagrass vegetation because of the great need to ~~~~~","~c~,"~~~",d~,",","~,","$",",",","~$~ restore estuaries in the Panhandle. heavy growths of phytoplankton and filamentous Agricultural clearing of uplands, real estate algae and higher turbidity. These growths reduce development, logging, and channelizing the available light and nutrients for seagrasses and may increase the rate of erosion of sediments, detrialso reduce oxygen levels for seagrass respiration tus, and mineral nutrientsand mavcause hiah in~uts during hours. of 'sediments into estuaries and coastal aieas (Thayer et aL 1975). 7.2.11 Subtldal Leaf Litter a. Introduction. The leaf-litter habitat in the The direct impact from oil on subtidal seagrassPanhandle is basically detritus dominated by pine es is not assevere as it is on intertidalplants(i.e., sal needles and oak leaves. It is generally concentratmarsh grasses) because the majority of the oil will ed near river mouths in the estuaries. The habitat is
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7. Estuarine, Saltwater Wetland, and Marlne Habitats 7.3 Marine Habitats 7.3.1 Hard Substrates a. lntroductlon. As in the estuarine system, there are not many naturally occurring hard substrates present in the Panhandle marine intertidal regions. Most of them are artificial (e.g., pilings, jetties, offshore platforms, and boat bottoms). Although limited in area, the habitat is discussed because it contains a unique and ecologically interesting fauna. Community development on structures is economically important because of biofouling problems. For example, marine fouling reduces ship propulsion efficiency by increasing frictional drag and destroys wharf pilings. It is also a problem on buoys and other structures in the marine environment. b. Associated flora and fauna. Marine algae on platforms tend to be small and inconspicuous. Two colonial forms are present: Enteromorpha and Chaetomorpha. Generally the dominance follows this order: green, red, blue-green, and brown algae (Salsman and Ciesluk 1978). For photosynthetic reasons, algal biomass is concentrated near the surface waters. Algae are usually one of the first colonizers of new or open solid surfaces. There is considerable variation in biofouling communities in the type of organisms present and in their size and density (Hastings 1972). The system is dependent on season, water depth, distance from shore, and larval availability (Pequegnat et al. 1967, Pequegnat and Pequegnat 1968). The nature of the substrate also plays a major role. The settlement rate of larvae isoften determined by surface contour, texture, composition, and color. Light levels, water currents, and tidal range are also important. There appears to be a predictable sequence in the development of a Panhandle fouling assemblage (Salsman and Ciesluk 1978): (1) initial settlement and rapid development of pioneer species; (2) a rapid and then more gradual increase in species diversity; (3) an early increase in size and density of nearly all individuals; (4) a decrease in the abundance of some species with the local extinction of others; and (5) the persistence of a few species, which facilitates the settlement of later arriving species. The pioneer "guild" includes a community of bacteria, diatoms, and blue-green algae that produce a slime-like surface. During the first week of exposure, barnacles, hydroids, and gammarid amphipods usually appear. Most of these are primarily suspensionfeeders. Othertrophictypes settle later. Three species of acorn barnacles (Balanus venustrus, B. improvisus, and B. eburneus) are typically encountered in the Panhandle (Hulings 1961). Balanus venustrusis usually the most abundant species. Five species of gammarid amphipods are also present (Salsman and Ciesluk 1978). Twenty-three species of hydroids are present in the lower intertidal to subtidal range. The most prominent difference between Panhandle estuarine and marine biofouling communities is the dramatic decrease in organism settlement and growth found in estuaries during the winter months (November-March). Offshore petroleum structures represent unique artificial habitat areas. They may act as islands of hard substrate in otherwise soft-bottom habitats. Gallaway et al. (1981) delineated three distinct biofouling assemblages that are present in the northern Gulf of Mexico region: coastal (0-30 m), off shore (30-60 m), and bluewater (> 60 m). Coastal plat, forms are typically dominated by barnacles with hydroids, bryozoans, and sponges also abundant. Oysters may be present too. Offshore communities are similar but are dominated by bivalves instead of barnacles and usually have lush populations of octocorals (e.g., Telesto spp.) and algae near the surface. Bluewater biofouling assemblages have the lowest biomassof thethree types. Algae and stalked barnacles dominate near the surface with bivalves more abundant at greater depth. Because of the extensive biofouling communities, petroleum platforms are subjected to increased frictional drag from wave and current action. For economic and structural reasons, biofouling communities are extremely important. They tend to decrease the longevity of the platforms and hence increase the cost of offshore operations. Organisms on platforms are usually restricted to a particular
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Panhandle Ecological Characterization depth range, and communities found in the nearsurface intertidal range are similar to those from the nearshore intertidal environment. 7.3.2 Sandy Beaches a. Introduction. The marine sandy beaches in the Panhandle are located on the gulfward-facing shores of the barrier islands (Dog, St. George, St. Vincent, Shell, and Santa Rosa Islands) and on the mainland shores from Cape San Blas to Pensacola. These intertidal habitats experience the highest wave-energy levels of any habitat type in the Panhandle saltwater environment. This beach habitat includes the swash zone (the sloping surface of the beach face that is created by the runup of water) down to the mean low water (MLW) mark. Panhandle beach sediments are composed almost exclusively of fine quartz grains with a median diameter of 0.1 to 0.2 mm (Salsman and Ciesluk 1978). Their extreme white color makes them attractive to tourists. The aerobic zone (i.e., depth of oxygenated sediment) in beach sediments is very deep because of tidal flushing and the relatively large interstitial pore spaces. This allows organisms to live far down within the sediment and escape the pounding of the waves. The majority of beach organisms tend to be suspension feeders, using the rushing water to constantly carry food in and waste material away. b. Beach zonation. Panhandle beaches are typical marine beaches and can be divided into specific zones (Figure 87). Typically, there are two offshore sandbars, the first located approximately 15-25 m offshore at a depth of 0.3-1.0 m, and the second 130-1 40 m off shore in 2-2.5 m of water. c. Associated fauna. The macrofauna component has been the most intensively studied (Abele 1970, Hayden and Dolan 1974, Saloman and Naughton 1978, Saloman and Naughton 1984) (Table 41 ). Polychaetes dominate numerically. Amphipods (also called "sand fleas") and ghost crabs ( Ocypode quadrats) are also important members of the community. Figure 87. A high-energy beach community, showing major zones relating to sand motion (adapted from Riedl and McMahan 1974). Physical Zonation PROFILE SEA WRACK Sea Oats Cabbage Palm Benthic DlatomS IThalassia & other Australian plant & animal Bedstraw Sea Grape A SURF ZONE boIlision Bar I Trough I Transit ion OFFSHORE BEACH Swash Zone Germ Trough Oscillatory Waves Breaker DUNE STRAND
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7. Estuarine, Sailwater Wetland, and Marlne Habitats Table 41. Common macrolnvertebrates present on Panhandle beaches (Haydenand Dolan 1974; Saloman and Naughton 1978,1984 ). Species name Common name Along wave line: Emerita talpoida mole crab Lepidopa benedicti decapod Callianassa islagrande decapod Arenaeus cribrarius decapod Scolelepsis squamata polychaete Haustorius spp. amphipod Upper portion of beach: Ocypode quadrafa ghost crab One meiofaunagroup,thetardigrades(or"water bears"), are usually very abundant in beach sediments. A common Panhandle species is Barillipes mirus. Birds are conspicuous members of the beach habitat and nearshore gulf waters. Common Panhandle seaand shorebirds include: pelicans, wrmorants, gulls, terns, sandpipers, plovers, stils, skimmers, and oystercatchers (see Table 42). d. Specles of speclal concern. The Cuban snowy plover (Charadrius alexandrinus tenuirostris) is the only bird species in Floridathat relies solely on the sandy beach for nesting and foraging habitat (Kunneke and Palik 1984). It is listed as an threatened species by the Florida Game and Fresh Water Fish Commission. It requires isolated, expansive sandy beaches for nesting. Breeding occurs from April to June. Its eggs (usually three) are laid in a shallow depression, which the parents occasionally line with seashell fragments. The mammals, the Choctawhatchee beach mouse (Peromyscus polionotus allophrys) and Perdido Key beach mouse IP. wlionotus trissvlle~sis), were listed as endangered by the ~edeial govknment in 1985. Panhandle beaches are nesting grounds for sea tultles. The Atlantic loggerhead (Caretfa caretfa), nests yearly (August through October) on the beaches from St. George Island to Okaloosa County. e. Trophic dynamics and interactions. Most of the organisms such as mole crabs (Emerita talpoida) are suspension feeders. Some, such as the ghost crab, are also scavengers. Birds prove an intricate palt of beach food-chain dynamics. They represent the top trophic group in the beach system, feeding on crustaceans, polychaetes, mllusks, and fish. Table 42. Common seablrds and shorebirds present along Panhandle beaches (Lowery and Newman 1954, Sprout 1954). Common name Scientific name American oystercatcher Black skimmer Common tern Double-crested cormorant Eastern brown pelican Laughing gull Least tern Royal tern Sandwich tern Snowy plover Wilson's plover Haematopus palliatus Rynchops nrgra Sterna h~mndo Phalacrocorax auritus Pelecanus occrdentalrs carohensrs Lams atrrcrlla Sterna antrllamm Sterna mwma Sterna sandvrcensrs Charadrius alexandrrnus tenuirostrrs Charadnus wrlsonra
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Panhandle Ecologlcl 11 Characterlzatlon f. Natural Impacts. Morton (1976) and Chiu (1977) reported the effects of Hurricane Eloise on Panama City beaches. The storm occurred in September, 1975, and caused extensive beach erosion, primarily by storm surge, wave setup, and beach scour (Figure 88). Wind and flood damage to the beach were minimal. Sediment was transported westward. The effectsof Eloise on the benthicbeach fauna was reported to be minimal and temporary (Saloman and Naughton 1977). Numbers01 benthic individuals were approximately the same before and after the storm. Numbers of species increased just after the storm but rapidly returned to prestorrn levels. Beach erosion is affected by fluctuations in sea level, wave conditions, longshore currents, atmospheric conditions, and human activities. The current sea-level rise of 0.5-1 .O crnlyr corresponds to a rate of shoreline retreat of about 0.3-1 Wyr. Shoreline erosion is not a constant, gradual process but appears to take place most severely during periods of intense wave activity, storm tides, and storm surges such as occur during hurricanes and other tropical storms (Ho and Tracey 1975, Walton 1978). Dredging navigational channels through inlets below their natural depths may enhance beach erosion by increasing the capability of the channel to flush sand out of a bay system. A channel can also act as a barrier to sand transported along the Coast by longshore drift and depletethe supply todowncurrent beaches. In a similar manner, structures such as jetties at inlets can cut off the natural supply of sand and direct it offshore. Beach erosion is a problem in Bay County in areas such as Biltmore Beach and Mexico Beach, where erosion rates of 1 Wyr have been documented. g. Human Impacts. Trash, noise, andsediment disruption are the major disruptions created by recreational beach users. The Panhandle has over 900,000 linear ft of recreational beach coastline. The effect on the benthicfaunafrom sanddeposition during beach restoration is reported in Only a few instances (Thompson 1973, Hayden and Dolan 1974, Culter and Mahadevan 1982). Results of a study on a Panhandle beach (Panama City Beach) appear consistent with other reports (Saloman and Naughton 1984). The deposition of ollshore sand Old Veg Llne 7 Elev 0 DISTANCE lftl Figure 88. Change In Panama City beach profile after Hurricane Eloise In September 1975 (after Morton 1976). 230
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7. Estuarine, Saltwater Wetland, and Marine Habitats onto the beach produces only short-term minor effectSOnthe benthicfauna. Forfive tosixweeks after deposition, species numbers and densities decrease in the swash zone. Alterthis period, populations return to pretreatment levels and stabilize. Overall, the beach fauna appearrelatively resilient to this type of disturbance. There have been no reports of the effects of beach renourishment on higher trophic organisms such as birds. Renourishing beaches with offshore dredged sediments wsts an estimated $1 millionlmi of restored beach inlially and requires about $25,0001mil yr to maintain (Kunneke and Palik 1984). Artificial structures such as seawalls, offshore breakwaters, groin fields, rock revetments, and jetties tend to aggravate beach erosion rather than slow or stop it. 7.3.3 Marlne Open Water a. Introduction. The nearshore and offshore marine open water habitat is physically stable compared to that of the estuaries. Salinity varies very little throughout the year and temperatures do not fluctuate as much or asquickly inthe marine system. Primary productivity in marine open waters of the Panhandle is lower than that of estuaries since the nutrient input is lower. Trophicdynamics are basically similar. There is overlap in the species present in the two systems. Many fish use the estuaries as nursery areas and migrate to deeper marine waters as adults, eventually to spawn. This habitat includesthe prized sport and commercialfish such as grouper (Mycteroperca spp.), Spanish mackerel (Swmberomoms maculatus), king mackera1 (S. cavalla), dolphin (Coryphaena hippurus). and billlish (Istiophoridae), and invertebrates such as the brown shrimp (Penaeus azfecus). b. Species present. The reduction in primary productivity in marine open waters is accompanied by a higher phytoplankton species diversity (Steidinger 1973) and characterized by more holoplanktonic forms than spore-forming meroplanktonic forms. Many of the diatoms and dinoflagellates that occur in the estuaries are also present in the nearshore marine system (Table 43), but in smaller numbers. Dinoflagellate diversity may exceed diatom diversity in the marine system. Table 43. Common plankton present In the Inarlne open water habitat of the Panhandle (Steldlnger 1973). G~OUD S~ecles Phytoplankton Diatoms Chaetoceros compressum Guinardia flaccida Hemiaulus hauckii Plagiogramma vanheuckii Rhyzarolenia imbricata Rhyzarolenia robusta Thalassiothrix famenfeldii Dinoflagellates Ceratium carriense Ceratium furca Ceratiurn fusus Ceratium massiliense Ceratium trichoceros Peridium spp. Blue-greens Oscillatoria erythraea Zooplankton Copepods Eucalanus monachus Nannocalanus minor Terma spp. Undinula vulgaris Chaetognaths Sagitta elegans Decapod Larvae Mysids Bowmaniella dissimilis Mysidopsis almyra Taphromysis bowmanni Phytoplankton demonstrate vertical stratification because of photosynthesis requirements (Steidinger 1973). Grazing zooplankton generally peak in abundance in areas of concentrated phytoplankton patches. The plankton are also seasonal in abundance (Figure 89). c. Recreatlonally and commercially Irnportant species. To the west of Cape San Blas the Continental Shelf is relat~vely narrow, and numerous pelagic species are found relatively close to shore. Important commercial and recreational species in
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Panhandle Ecological Characterization Inshore trolling grounds off Panama City are important summer sportfishing areas for Spanish and king mackerel, Atlantic bonito, and dolphin. The area off the entrance to Pensacola Bay is a popular summer sportfishing area for Spanish and king mackerel, bluefish, and cobia (Rachycentron canadum)(Trent and Anthony 1978). In the Panhandle, a number of charter sportfishing boats, numerous private boats, and party Jan Feb Mar pr Ma Aug Sep Od Nav Jan boats (also called head boats) fish the nearshore urn* marine waters durin~ the warmer months (Fable et Figure 89. Seasonal phytoplankton abundances in the northeast Gulf of Mexico (after Steidlnger 1973). this region include brown shrimp, white shrimp (Penaeus setiferus), and pink shrimp (P. duorarum), Atlantic bonito (Sarda sarda), greater amberjack (Serioila dumerilr), crevalle jack (Caranx hippos), blue runner (C. crysos), sharks, spot (Leiostomus xanthurus), Atlanticcroaker (Micropogonias undulatus), sand seatrout (Cynoscion arenarius), gulf menhaden (Brevoortia patronus), bluefish (Pomatomus saltatrix), Spanish and king mackerel, Atlantic thread herring (Opisthonema oglinum), Spanish sardine (Sardinella anchovia), and the billfishesblue marlin (Makaira nigricans), white marlin (Tetrapturus albidus) and sailfish (Istiophon/s platypterus) (Pristas 1981) (Table 44). Five marine turtleswith special status are also found inthis region (Table 45). al. 1981, Kunneke anh Palik 1984) (Table 46). Trolling techniques are usually used with king mackerel, Spanish mackerel, bluefish, blue runner, little tunny (Euthynnus alletteratus), Atlantic bonito, and dolphin. These seven species make up a majority of charter boat catches. Yearly species composition during the 1970'swere king mackerel (61%), Atlantic bonito (15O/0), bluefish (5%), blue runner (5%), little tunny (5%), Spanish mackerel (4%), and dolphin (4%). Trolling effort in the Panhandle is greatest off shore of Panama City and Destin. Historically, the sport fishery has been mostly dependent on king mackerel catches (Brusher et al. 1976, Fisher 1978). Dramatic changes in the landings, species composition, and sizes of fishes in the summer of 1977 and 1978 in the charter boat pelagicfishery off Panama City have been correlated to large changes in air temperatures during the preceding winters (Fable et al. 1981). During 1970-76 and 1979, king mackerel generally dominated the catch, ranging from 57.2% (1979) to 92.9% (1970) (Fgure 90). Table 44. Common fish specles present in marine open waters of the Panhandle. Species name Common name Species name Common name Caranx crysos Coryphaena hippurus Epinephelus morio Euthynnus alletteratus lstiophorus platypterus Lutjanus campechanus Makaira nigricans Mycteroperca microlepis Pagrus pagrus Blue runner Dolphin Red grouper Litle tunny Sailfish Red snapper Blue marlin Gag Red porgy Pornatomus saltatrix Bluefish Rachycentron canadum Cobia Rhomboplites aurorubens Vermilion snapper Sarda sarda Atlantic bonito Scomberomorus cavalla King mackerel Scomberomorus maculatus Spanish mackerel Sphyraena barracuda Great barracuda Tetrapturus albidus White marlin Thunnus thynnus Bluefin tuna
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7. Estuarlne, Saltwater Wetland, and Marine Habitats Table 45. Marlne turtles with special status that occur in Panhandle marine waters. Common name Specles name Status Atlantic green turtle Chelonia mydas mydas Endangered Atlantic hawksbill Eretmochelys imbricata imbricata Endangered Atlantic leatherback Dermochelys mriacea Endangered Atlantic loggerhead Caretta caretta caretta Threatened Atlantic ridley Lepidochelys kempi Endangered Table 46. Charter and party boat principal ports of call (Schmled 1982, Waterway Guide, lnc. 1982). Number of Number of County Ports of call charter boats party boats Escambia Santa Rosa Okaloosa Walton Bay Gulf Franklin Total Pensacola Gulf Breeze Destin Harbor Ft. Walton Beach Harbor Shalimar Harbor Santa Rosa Beach Panama City Mexico Beach 60, Y 55 I. 0 f 50457 62636465666768697071 72737475767778i3 Year In general, king mackerel are available to the Figure 90. Correlation of pelagic fisheries to fishery in the Panama City area in April, are abunchanges in alr temperatures off panama City dant during June to November, and are most abun(Fable et al. 1981). dant, orcatchable, in September. The king mackerel xm . . . . . . . . -4.0 Atlantic same time bonito periods. ranged In from the zero summers to 7.1% of during 1977 and the 1978, king mackerel made up only 38.7% and 18.9%, respectively, of the total catch, while Atlantic 3 bonito comprised 29.5% and 47% of the totals. -20 b These changes corresponded to unusually low % temperatures during the 1976-77 and 1977-78 5 winters. Successful king mackerel migration into Panhandle waters, therefore, appears dependent upon water temperatures that are not far below r0.0 normal.
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Panhandle Ecologlcal Characterization in this region winteroff the southeast coast of Florida evidenced by the nonschooling or nonaggregating (Sutherland and Fable 1980). Of the remaining six species, such as synodontids and triglids, found species. Atlantic bonlo, blue runner, littletunny, and during gut sampling. Since it usually bites or chops dolphin have been most abundant in the catches the prey in half, a whole fish is rarely found in a king during June or July, while bluefish have been most mackerel stomach. abundant in May and November, and Spanish mackerel in March (Fable et al. 1981, Goodwin and (2) Dolphin. Dolphin appear in panhandle waFinucane 1985). ters from April to December with May and August beina the Desk months. Their maximum lifes~an is ~h~ size of king mackerel caught off panama appGxirnitely 4 years. ~olphins tend to form closecly varies G~~~~~~~~, mean lengths are knit schools. They are prey to awidevariety of ocean greatest at the beginning of each fishing predators and are cannibalistic. When hooked, a decline to a low in August, and then indolphin rarely tries to escape by diving downward. crease in September or October. Venical distribution is generally limited from the surface to approximately 30 m. The billfish sportfishery began inthe mid-1 950's (3) Brown shrimp, Brown shrimp are reported to off the Panhandle. Sportboats originate primarily spawn primarily in open gun waters deeper than 18 from Pensacola, Destin, and Panama City. In ,and mssihlv un to 14n m ~hn snawninn snasnn ... -. Destin, sailfishwere caught as early as 1955, butthe extend;irG ~,$t&,,bbi Tio rep~od~~~;e firstwhite marlin Was landed in 1959 and the first blue Desks mav occur in nearshore panhandle marine marlin in 1962 (Nakamura and Rivas 1974). An early ivaters: 'September-~ovember and ApriCMay. history of thedevelopment of the billfish sportfishery Fishing begins in May, peaksin June and July during in the Panhandle region is included in Siebenaler's their seaward migration, and continues through (1965) work. November in offshore waters. A major bilnish area is located off Pensacola nearthe Desoto Canyon. Typically, white marlin are more abundant in July and sailfish are more abundant during the latter half of September, while blue marlin do not have an especially abundant period. Usually, the bluer the water, the greater the relative abundanceof bilnish. Off the Panhandle, blue marlin prefer mullet as bait, sailfish prefer bonito, and white marlin show no preference (Nakamura and Rivas 1974). The habitat and dietary preferences of the major sport and commercial fishes are summarized below. (1) King mackerel. The diet of king mackerel includesfishfrom 31 families (Saloman and Naughton 1983). Clupeidae are the dominant prey. Other families of importance include Carangidae, Sciaenidae, Engraulidae, Trichiuridae, Exocetidae, and Scombridae. The round scad, Decapterus punctatus, is the most important prey species in the diet of king mackerel caught in the Panhandle. Squid are the dominant invertebrate prey. King mackerel are primarily piscivorous, feeding heavily on schooling fishes. They are also opportunistic feeders, as All feeding stages are omnivorous. Larvae feed in the water column on both phytoplankton and zooplankton. Postlarvae live and feed in the estuaries. Shrimplargerthan65 mmthat live indeepwater are more predaceous than small individuals, with occasional detritus and algae being ingested. Prey items include polychaetes, amphipods, nematodes, and ostracods. The shrimp itself is prey to a host of fishspecies, many of which are commercially important. d. Specles of special concern. Five speciesof marine turtles (Table 45) and three species of whales-finback whale (Balaenoptera physalus), sperm whale (Physeter catodon), and humpback whale (Megaptera novaeang1iae)-that occasionally occur in Panhandle waters are threatened or endangered. e. Natural impacts. Some phytoplankton species can cause large fish kills and are toxic to shellfish. These species cause what are termed red tides because of the discoloration of the waters. Marine coastal red tides in the Panhandle are primarily associated with population blooms of the
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7. Estuarine, Saltwater Wetland, and Marlne Habitats dinoflagellate Ptychodiscus brevis (formerly Gyman artificial reef can mimic those on a natural reef nodinium breve) or Gonvaulax monilata. Usuallv within 8 monthsof Dlacement (Stone et al. 1979). In coicentrakd iihin 48 iri of the coastline, these species produce a neurotoxin that, in sufficient concentration, is capable of paralyzing and killing a number of fish species. The effects on larval invertebrates is not well known. Most major red tides last 24 months. In addition to having an effect on nearshore fisheries, red tidescan also affect tourism along a coast because of the odor of decaying fish. 1. Human impacts. Oil drilling activities (i.e.. boat traffic, mud cuttings, spills, etc.) can have a variety of effects on water column species. Many larger pelagic species such as fish can avoid oil spills, but small planktonic species are vulnerable to direct effects. Offshoreoil spills pose apotential impact for sea turtles, especially juvenile turtles. Floating oil could increase the mortality rate of turtles directly by contacting the turtles when they surface to breathe and indirectly by affecting food sources. Dolphins have been observed swimming and feeding in oil slicks and oil apparently does not adhere to their smooth skin (Geraci and St. Aubin 1982). It appears unlikely that dolphins inhale oilinto their blowholes while breathing. Some hydrocarbon-contaminated food or water could be ingested: however, the effects of hydrocarbon ingestion by marine mammals is unknown. 7.3.4 Anlflclal Reefs a. Introduction. Artificial reefs are objects of human or natural composition that are placed on selected sles in the aquatic environment to attract and stimulate the growth of larger fish and invertebrate populations. The primary purpose is the promotion of sport (and in some cases commercial) fishing by attractingfood and game fish to a location easily accessible to fishermen and sport divers (i.e.. spear fishermen). Artificial reefs benefit anglers and the economy of the neahy shore community, in the lattercase by attractingout-ofcity fishermen intothe community. The purpose of the artificial reef is to duplicate conditionsof naturally occurring reefs or hard bottom areas. Numbers of fish species and abundances on addition, they can' effectivel; improve an already existing rough-bottom habitat and provide a functional management tool for reef fish resources. They also are potential nursery grounds for various species because they provide shelter from predators. The reef provides the inhabitants with a refuge from predation and, in some instances, strong currents. Inaddition, thefoulingorganisms that encrust the reef become food items for small foraging fish that, in turn, attract larger predatoty fish. If large enough, artificial reefs may increase the primary productivity of an area by creating an upwelling effect that causes nutrient-rich bottom water to mix with upper water layers. Artificial reefs may be of two types: high profile or low profile. High-profile reefs are usually the most productive because they attract bottom species such as grouper, sea bass, and snapper and also pelagicforms such as Spanish mackerel, cobia, and amberjack. The high profile reefs, however, require greater depths to prevent them from becoming navigation hazards. Low-profile reefs are more useful inshallowerinshore areas andare effective in attracting demersal fish. Florida has initiated more reef construction than all the other Southeastern States combined (Seaman 1982). The Panhandle region is one of the primary artificial reef areas in the State (Seaman and Aska 1985). Artificial reef construction in the area reflects a number of influences: (1) the vast amount of coastline, (2) an increase in population growth along the coast, (3) a leisure-oriented population along the coast with a number of party and charter boats (Table 46), motor-powered boats, and marinas and boatyards. Besides the large number of verified artificial reefs in the Panhandle, there are a number of unauthorized "private" reefs in use. The artificial-reef program in Florida is administered by the Florida Department of Natural Resources, Division of Marine Resources (Section 370.013 of the Florida Statutes). Panama City has an artificial-reef program directed by the Panama City Marine institute that began in July 1978.
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Panhandle Ecological Characterization Establishment of the first documented artificial ciated with eight artificial reef sites off Panama City. reef in Florida was in the Panhandle region off The fishcommunity can be divided into threeclasses Pensacola in 1920 (Seaman and Aska 1985). Dur(Chandler 1983): resident species, semi-resident ing the next 50 years there was only sporadic conspecies, and transient species. Resident species struction. However, intheearly 1970'saaivitygreatgenerally make up the largest of the three groups ly accelerated. and are dependent upon the reef for food and shelArtificial reefs are constructed from very diverse rnaterials. Nearly all Panhandle reefsare comprised of ships (e.g., barges), automobiles, tires, or concrete rubble. Most reefs can be classified on the basis of a single predominant material. In some cases, it is diificult to assign a reef toonecategory on the basis of composition because some established reefs are being expanded with new and different rnaterials. There is a trend toward longer-lasting, denser materials such as tires and automobiles as well as toward improved methods of placement. b. Distribution. There are at least 61 verified reefs within the Panhandle region (Kunneke and Palik 1984, Seaman and Aska 1985 )(Figure 91). The average distance offshore is approximately 12 km. Average depth is approximately 20 m. Panhandle atiiicial reefs have been placed principally in oceanic locations with a few exceptions, such as one in Choctawhatchee Bay near Fort Walton Beach. Depth and distance from shore is variable. Because the Continental Shelf is relatively shallow at great distances from shore, it is not unusual that a reef be placed 24-32 km offshore to approach a 10-20 m depth. Like planned artlicial reefs, shipwrecks attract fish by providing structure on an otherwise flat sea floor. The National Ocean Survey maintains updated information on all known shipwrecks in U.S. coastal waters. Table 47 gives a list of major shipwreck sites in the Panhandle region. c. Assoclated fauna. Fish are the mst intensively studied group associated with Panhandle artificial reefs (Table 48). Other groups such as the encrusting and free-living invertebrate communities (e.g., sponges, gorgonians, and bryozoans) are not well documented. Fish communities on a~lificial reefs are very diverse. Sanders (1983) reported 72 species assoter. The semi-resident group includes fish that are not dependent upon reefsforfood andsheheranddo not maintain permanent residency on the reef. This group is typically represented by schooling pelagic species (e.g., jacks) or suprabenthic species (e.g.. vermilion snapper Rhomboplites aurorubens). Semiresident fish generally do not use the reef for protective cover but as a visual reference point or food source. Transient species form a catchall category that includes speciesfound infrequently on the reef and whose dependence on the reef Is unknown. The complexity of a reef sultace is an important factorfordeterminingthe abundanceanddiversity of the resident fish community. Chandler (1983) concluded from two artificial reefs (barges) off Panama Citythat the morecomplex structure hada larger and more diverse fish assemblage. The primary factors appeared to be the greater availability of space and food resources (i.e., epifaunal invertebrates and biofouling communities) on the more complex structure. Contributing to increased abundance and diversity is the vertical relief of an artificial reef. Greater vertical relief offers additional space, and also represents a stronger visual marker or cue for nonresident or transient species. Water temperature appears to be the single mst important factor that controls species composition in Panhandle artificial reef fish communities (Sanders 1983). Increasing temperatures in the spring and summer usually mark the appearance of typically tropical species such as the white grunt Haemulon aurolineatum, cocoa damselfish Pomacentrus variablis, and painted wrasse Halichoeres caudalis. Chandler (1983) reported that seasonal changes in the structure of resident fish communities in Panhandle artificial reefs were affected primarily by rec~itment of new members during the summer and by higher predation and mortality rates in the winter.
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7. Estuarine, Saltwater Wetland, and Marine Habitats ALABAMA Year Depth County # Built Latitude Longltude (ft) Wakulla 1 1964 30'00" 84'15" 20 2 1964 2g055'42" 8413'06" 21-30 3 1964 3000'06" 8417'06" 15 Franklin 4 2924'54" 5 1981 2930'48" 6 1981 2932'12" 7 1982 2931'05" 8 1979 2917'55" 9 1980 2917'06" 10 1973 2924'24" 11 2931'12" Gulf 1 1964 2g05024" 85O29'18" 40 2 1971 2g053'15" 85'32'00" 44-70 Year Depth County # Built Latitude Longltude (ft) Walton 12 1972 30'24'38" 86'08'48" 9 13 1972 30'25'56" 86'14'18" 13 14 1972 30'58" 86'14'34" 13 15 1972 30'2436" 86'17'35" 7 Okaloosa 16 17 1977 18 1976 19 1977 20 21 1976 22 1977 23 1977 24 1979 Santa Rosa 25 1980 30'46" 86'48'20" 70-80 Escambia 26 27 28 29 30 31 32 33 87"04'00" 175 87"07'06" 85 87"07'30" 60 87"09'07" 67 87O13'12" 20 87O13'13" 45 87O18'42" exposed 87'25'36" 20 Figure 91. Artificial reef locations in Panhandle waters (after Aska and Pybas 1983). 237
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Panhandle Ecologlcal Characterization Table 47. Shlpwrecks In Florlda Panhandle waters (Beccasio et al. 1982). Shlp name Latitude Longitude Depth (ft) Unknown Unknown Eastern Light Anna Pepina Bride of Lorne Unknown Unknown Unknown Unknown Unknown Unknown Unknown Vamar Semiresident species emigrate from a reef as water 7.3.5 Subtldal Rocky Outcropplngsl Natural temperatures drop. Reefs Table 48. Some resldent reef fish from elght artiflclal reefs off Panama City, Florida (Chandler 1983, Sanders 1983). a. Trophic dynamlcs and Interactions. Trophicdynamics on artificial reefs inthe Panhandle are not well documented. Most likely they are not much deferent from those of natural tropical reefs. The biofouling or enc~ating communhy probably represents an important food resource to many reef resiCommon name Sclentlflc name Bandtail puffer Sphoeroides splengleri Black sea bass Centropristis striata Blennies Family Blenniidae Cocoa damselfish Pomacentrus variabilis Gag Mycteroperca microlepis Jackknife-fish Equetus lanceolatus Orange filefish Aluterus schoepfi Reef butterflyfish Chaetodon sedentarius scam^ Mvctero~erca hena ax a. Introduction. Subtidal rocky outcroppings are areas of hard, rugged bottom relief, usually comprised of limestone (Jordan 1952, Salsman and C~esluk 1978). These areas have been called "live bottoms" by the State of Florida in its designation of regions that are sensitive to oil drilling activities. Thev are scattered throuahout the area in deoths of Common name Sclentlflc name Scrawled cowfish Lactophyrys quadricornis Sheepshead Archosargus probatocephalus Spotfin butterflyfish Chaetodon ocellatus Twospot cardinalfish Apogon pseudomaculatus White grunt Haemulon plumieri Yellowtail reeffish Chromis enchrysums dents. In turn, top carnivores such as the barracuda 18-j0 m of water: some iie as close as 1 5 kh from (Sphyraena barracuda) and jacks feed on the shore. Most of them protrude less than a meter smaller schooling species. above the surrounding sediment. Occasional small, 238
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7. Estuarine, Saltwater Wetland, end Marine Habitats isolated outcrops are also known nearshore in the known about the mechanisms and interactions that St. George Sound area (e.g., Dog Island Reef). are important in any given location. This habitat represents a contrasting environThe habitat ranges from the mean low water rnent to an othewise soft-sediment dominated sysmark offshore and includes practically all the area tern. The hard substrate offers an attachment suroffshore except rocky outcroppings. However, for face fora variety of organisms such as Sponges and this report, only the region to the Continental Shelf algae. break is covered, with the inshore areas stressed. b. Associated flora and fauna. Offshore rocky outcroppings are usually areas of fish concentrations (Saloman and Fable 1981, John E. Chance and Associates, Inc. 1984) (Figure 92). An area known as the Timberholes is an important recreational and commercial red snapper (Lufianus campechanus) ground. Vermilion snapper, red grouper (Epinephelus mria), gag (Mycteroperca microlepis), and red porgy (Pagrussedecim) are also taken. This ground IS the inshore edge of Desoto Canyon, a submarine canyon in open gulf waters. Desoto Canyon is one of the majorbillfish sportfishing areas in the eastern Gulf of Mexico. Some of the major species caught include blue marlin, white marlin, and sailfish. A diverse sponge fauna is usually present (Little 1958). Red algae are usually attached to the hard substrate. Common species include Euchema acanthocladum, Botrylcladia uvaria, and Callithamnion byssoides. The relief is sometimes augmented by recent coral growth. Coral growth has been reported on a rocky outcrop 3 to 12 km offshore between Panama City and the Choctawhatchee Bay entrance. Nonhermatypic corals such as Madracis asperula, Cladocora sp and Paracyathus sp. are common. Red algae are usually attached to the hard substrate. Nonhermatypic corals such as Madracis asperula, Cladocora sp., and Paracyathus sp. are common. 7.3.6 Subtidal Soft Bottoms a. I.itroduction. As with the estuarine system, the marine soft bottom habitat constitutes the largest environment (on an area basis) within its system. There have been numerous su~eys of the fauna in this habitat (e.g., Salsman and Tolbert 1965 and Loftin and Touvila 1981), but very little experimental work because of access problems. Most samples are taken from ships with remote devices such as box cores, dredges, trawls, and epibenthicsleds. As a result, most reports are descriptive and little is b. Physlcal description. The nearshore zone is comprised of fine quartz sand (0.1-0.2 mm median diameter) that extends out across the shallow barrierbarandto adepthof l5to 18 m,wherethefine sediment becomes interspersed with a coarser brown sand containing shell fragments (Salsman and Ciesluk 1978). The coarser sediment has a median diameter of 0.3 to 0.5 mm. Wave-produced sand ripples with heights up to 2.5 cm and wavelengthsol 7.5 to 12.5cm are present much ofthe time in the shallow areas directly off the beaches (Salsman and Tolbert1961). Sand dollars are capable of flattening these ripples less than 24 hours aftertheir formation (Salsman and Tolbert1965). Large storm wavescan produce ripples inthecoarsersandfound in deeper waters. Sand ripples with heights up to 15 cm and wavelengths of 1 to 1.2 m that persist for up to 2 months may be produced (Salsman and Ciesluk 1978). c. Fauna present. A number of investigations have reported species collected from offshore soft sediments (e.g., Salsman and Tolberl 1965, Saloman 1976, Saloman 1979, Loftin and Touvila 1981, Saloman 1981, Uebelackerand Johnson 1984). As in the estuarine system, the marine soft-bottom organisms can be classified into a variety of functional groups based upon life-position, motility, and feeding mode. These classifications often make data easier to interpret when taxonomic problems or other constraints arise. The offshore Panhandle marine meiofauna are not well documented. However, there is probably some overlap between the nearshore marine assemblages and estuarine ones. The meiofauna, especially the polychaetes, have been examined (Uebelacker and Johnson 1984) Common species are given in Table 49 along with other common organisms.
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Figure 92. Cross-sectional view through a typical rocky outcropping off the Panhandle coast (John E. Chance and Associates, inc. 1984).
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7. Estuarine, Saltwater Wetland, and Marlne Habnats Table 49. Common invertebrates present In nearshore soft-bottom habitats In the Panhandle (Saloman 1976, Saloman 1979, Loftin and Touvlla 1981, Uebelacker and Johnson 1964). Microphthalmus spp. Nephtys bocera Nephtys picta Onuphis eremita Paraonis fulgens Prionospio spp. Scolelepsis squamata Group Species name Group Species name Decapods (caridean shrimp) Ambidexfer symmetricus Ogytides alphaerostris Processa henlphilli Processa vicina Tozeuma COfnUhlm Polychaetes Aflcidea spp. Armandia agilis Dispio unicinata Amphipods Cumaceans Spilocuma salomani d. Trophic dynamics and interactions. The occasional storm disruptions. Panhandle-specific trophiidynamicsof rnarinesoft-bottornwmmunities research in this area is nonexistent. in the Panhandle are not well studied. ~rimarilv for Spiophanes bombyx Syllidae logistic reasons. The general patterns are probably similar to those of estuarine soft bottoms. 1. Human Impacts. Localized impacts can occur from oil-drilling rigs placed on the bottom and Echinoids Encope mitchelli e. Natural impacts. The deeper offshore softfrom dredging, especially dredging for sand for bottom habiat is relatively free from natural impacts. beach renourishment projects (Saloman and Only the shallower nearshore areas are subject to Naughton 1984).
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Chapter 8. SUMMARY 8.1 The Panhandle In Review The Florida Panhandle has a varied subtropical climatewith hot, humid summers and brief periodsof below freezing temperatures in winter. Rainfall is abundant, averaging approximately 152 cm per year. This rain falls primarily during two rainy seasons, late winter and early spring (February through April) and summer (mid-June through mid-September). Winter rains are primarily a product of passing coldfronts; summer rains are primarily in theformof convective thunderstorms. Winds are normally out of the south to southeast during the summer and constantly change in the winter, being most commonly out of the north to northwest or the south to southeast. Tropical storms and hurricanes occasionally cause substantial damage from high winds and storm surge. Seven major rivers, the Ochlockonee. Apalachicola, Chipola, Choctawhatchee, Yellow, Blackwater, and Escambia, traverse the Panhandle on their way to the coast. The rivers of the western Panhandle tend to be highly colored, of low turbidity, and nutrient poor. Those of the eastern Panhandle are generally alluvial (sediment carrying) and nutrient rich. All originate out-of-State in either Georgia or Alabama. Changing land use and effluent discharges inthesestates, which practice less stringent water-quality regulation than does Florida, are hindering Florida's attempts to maintain or improve the quality of water in Panhandle rivers. In particular, out-of-State pollutants are affecting the Ochlockonee, Apalachicola, and Escambia Rivers. The flood plains of Panhandle rivers are largely undeveloped atthis time. Periodicflooding has been shown to be an important step in recycling nutrients in riverine ecosystems and to be responsible for much of the productivity of coastal estuaries. Damming rivers for flood control or other purposes prevents the transport of much of these nutrients to the estuaries, the nutrients are trapped in lakes behind the dams where they speed up the eutrophication of the lakes. Experience in other parts of Florida and elsewhere inthe United States shows that restricting development in flood plains is the best and most cost effective means of flood prevention. This prevents not only flooding of the developments in the flood plain, but also flooding in areas outside the flood plain which become more flood prone as a resun of the altered hydrology associated with development. Most of theground water used in the Panhandle iscontainedwithintwo aquifers: the Floridan Aquifer east of Okaloosa County and the Sand and Gravel Aquifer from Okaloosa County west. The Floridan Aquifer iscontained in a porous limestone matrix and is characterized by alkaline water with a moderately high level of dissolved solids. Beginning near Okaloosa County the Floridan Aquifer is increasingly deeper as one proceeds west and it becomes increasingly mineralized. The Sand and Gravel Aquifer is found above the Floridan in this western region and is more commonly used because of its better water quality. The terrestrial vegetation of the Panhandle was mostly open pine woods on rolling hills and flat lands before human alterations began. In the valley bottoms of the hill lands and along creeks in flatwoods a series of hardwood forest types were found. Regularly occurring natural fires that burned through the pinelands were extinguished downslope where soil moisture increased, keeping the fire-tender hardwood species from seeding underthe pines and taking over the uplands. Today, most of the dry land and even all the wetlands have been logged, often more than once. The natural tire cycles have been stopped or severely altered, and the woodlands of
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8. Summary most of the Panhandle are second-growth mixtures of pines and encroaching hardwoods, where timber has been cut and allowed to regenerate naturally, or has been converted to pine monoculture, agriculture, and urban and suburban development. The Florida Panhandle is a crossroads where animals and plantsfromthe Gull Coastal Plain reach their eastward distributional limits, where others from the Atlantic Coastal Plain reach their southwestern limits, and where northern species, including many Appalachian forms, reach their southern limits. There is also a contribution of species from peninsular Florida. So many species of plants and animals flourish in the wet, temperate climate of the Panhandle that the region may support the highest species diversity of any similar-size area in the U.S. and Canada. Because the Panhandle has high annual rainfall and low, gently sloping terrain, wetlands abound. The bogs, marshes, swamps, wet prairies, and wet flatwoods provide a diversity of wetland types that suppolt numerous species of animals and plants, including many endemic species and races. Wetlands seem to vary considerably depending upon slope, soil type, water chemistry, and fire cycle and there is a needfora more thorough investigation and classlfication to understand the significance of the differences. The seven Panhandle estuaries are, with the exception of Ochlockonee Bay, bar built (i.e., separated from the Gulf of Mexico by a sand bar or barrier island). They are nearly evenly distributed along the coast and are formed at the mouths of rivers, except for the two lagoonal estuaries, St. Joseph Bay and Alligator Harbor. The western Panhandle has a higher energy regime along its coast than the eastern portion as is evidenced by the associated sandy beaches. This situation arises because of the closer proximity of.the edgeof the Continental Shelf and the longer fetch, allowing the prevailing winds to generate greater wave energy. Seagrass beds cover a greater area in the eastern Panhandle than inthewestern. Thisresultsfrom the more suitable conditions for seagrass promulgation provided by the lowerenergy conditions along the coast in the east. Wihin the estuaries, this difference is correlated with the greater industrial development in the western Panhandle. Extensive losses in seagrass habitats in the western Panhandle estuaries have been documented and tied to human development (iie., industrial discharges and dredging). Panhandle salt marshes are prevalent and more evenly distributed than the seagrasses, though they are not nearly as extensive as those formed in the lower energy conditions along the adjacent Florida Big Bend Coast. Oyster reefs are found in all the Panhandle estuaries, but those in the western estuaries tend to be unusable by humans because oysters concentrate the contaminants introduced to the waters by surrounding development. Apalachicola Bay contains the largest concentration of commercially important oyster reefs. These relatively unalfected (by pollution) beds are presently experiencing potential contamination from septic tanks on nearby St. George Island. Oyster reefs in the Choctawhatchee and Pensacola Bay systems have experienced the most impact from industrial development in the nearby coastal regions and the majority of reefs are not harvestable. The Florida Panhandle is lightly populated except for an intensively developed and increasingly industrialized region along thecoast from Pensacola eastward to Panama City. This area has continued to develop rapidly from the densities indicated by the 1980 census (Figure 93). The only other population pressure in the area is from the State Capitol, Tallahassee, alongside the Panhandle's eastern border. The primary land use outside these two areas is forestry and farming. The Apalachicola National Forest, Blackwater River State Forest, Apalachicola Estuarine Sanctuary, St. Vincent Island and St. Marks National Wildlife Refuges, Gulf Islands National Seashore, and the St. Joseph Peninsula (T.H. Stone Memorial) and St. George Island State Parks as well as numerous smaller State forests and parks are located within the Panhandle. 8.2 Panhandle Findings The estuaries and nearshore marine habitats of the Florida Panhandle are some of the greatest natural and economic assets of the region. There is
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activity in the past 5 years and most of the important habitats of this area have been purchased by the State or by nonprofit conservation organizations. One significant area remains, however, that ought to be purchased: the limestone bluffsand ravinesin the vicinity of Aspalaga Landing. The Panhandle has high species richness in acid bog plants: possibly more carnivorous plant species occur in the Panhandle than in any similar size area in the wolld. These unique wetlands should be specifically inventoried for their biological composition; bogs are so variable that there may be several distinct types of bogs, each of which may need to be brought into the statewide inventory of publicly owned lands. Lacustrine environments of the Panhandle are diverse and mostlv unstudied. Thev range from temporary ponds inlow places and sinikho~edepressions to larae. Dermanent lakes with relatively dee~ water. An inventory, including acensusof the animal and plant components, is urgently needed and a categorization basedon hydrology, waterchemistry, and biota is long overdue. The Panhandle possesses unique streamvalley types called steepheads; these should be recognized for their uniqueness and inventoried for their biologicalcomponents. It is likely that some, at least, may contain endemic forms of life. The lands under the influence of the navigable freshwater bodies of the Panhandle are sovereign, belonging to the State, but for almost no navigable river or lake has the boundary between State owned lands and the upland riparian ownership been determined by survey. This causes acute environmental problems. Most of the floodplainsof the Panhandle have been logged by the adjacent landowners and continue to be affected. These publicly owned lands should be recognized as such and managed to preserve the riverine ecosystems in their natural state. The detritus that originates in the floodplain forests is one of the main forcing functions of the estuarine productivity that is so imporlant to the Florida Panhandle's seafood industry. Native upland ecosystems are the most altered ones in the Panhandle because these are the sites on which people live. There is not a good representatinoftheupland habitattypes in publicownershii, partly because there are few patches left that are undisturbed, and partly because these sites are targetedfordevelopment. We call for a review of the acreage of the important terrestrial wmrmnities remaining, and for an effort to set aside a representative selection to maintain species diversity and for posterity to eney. Two habiiatsof great importance in the Panhandle coastal region are salt marshes and seagrass beds. Salt marshes are critical nursery, feeding, and refuge areas for many commercially important estuarine organisms such as fish and crabs. The economic value of an acre of marsh has been estimated at 4 to 5 times that of the most productive farmland. The balance between a rising sea level and the sediment supply is being upset by human encroachment in nearby upland habitats, thereby directly and indirectly affecting the marshes. This habitat isone that requires very stringent monitoring for future protection. Seagrasses are vital to the coastal ecosystem because they form the basis of a structurally complex, three-dimensional habitat. Few other systems are so dominated and controlled by a single species as is the cllmax Thalassia meadow. If seagrasses are destroyed, more erosion occurs and the associated flora and fauna disappear, including wmmercially important species (e.g., fish, crabs, and scallops). Primary productivity and detrital production decrease dramatically, and this affects other habitat systems, such as unvegetated bottoms, that rely on organic import for the basis of their food chain. Despite extensive studies on seagrass productivity and on temporal and spatial variability in the biological composition of seagrass communities, little is known of the general principles on which the ecosystem functions and of the factors controlling ecological success in the community. Therefore, subtle changes that may be caused by human actiiities generally pass unnoticed or are ascribed to natural variation. An example is changes in turbidity levels. Light levels are extremely important for the seagrasses and over time, if light is decreasing, grass beds will slowly die off. Only gross damages, such as the tearing up of beds by dredging, are
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Panhandle Ecological Characterization described in the literature. However, it may be subtle changes in light levels that eventually take the largest toll on this habitat. It became painfully obvious during the writing of thisdocument that intensive studies haveonen been conducted at great expense, butthe resulting recommendations have not been implemented into area management plans or reflected in local ordinances and policies where they would be effective. The regulatory mechanisms in place often are inadequate to protect environmental resources. Additionally, studies sometimes duplicate previous efforts. There should be a more concerted effort toward coordinating research efforts to get the most Information for the dollar. We funher note the need to establish further standards for Outstanding Florida Waters (OFW's) and Aquatic Preserves as well as for their adjacent upland areas. Assigning one of these designations to an area without knowledge of its ecological state or the intent to gain this knowledge hinders enforcement of the regulationsthat are supposed to protect them. In some instances, the protective regulations and enforcement authority are not even in place, rendering the designation token at best. Though it has been so often repeated that it is sometimes regarded as an excuse, the ability to formulate effective, balanced management plansfor the Florida Panhandle is in many instances fatally hindered by the lack of information on which to base the necessary decisions. During our review of Panhandle emlogical literature, we noted many areas which have not been investigated. Questions concerning some of these information gaps may safely be answered using studies performed on similar areas elsewhere. However, experience has shown that the operations of ecosystems are so poorly understood that, at present and in the foreseeable future, the ecology of local ecosystems must often be regarded as unique. Even systems that appear identical may have achievedthe external similarity in response to the synergy of altogether different driving forces. Data gaps that were identified include: (1) biological baseline studies of estuaries (except Apalachicola Bay; a study is also underway of Choctawhatchee Bay), of rivers (one-year studies are underway for the Ochlockonee and Choctawhatchee Rivers), and lakes. These studies need to be several years in duration in order to provide a hint of the natural variability from annual climatic differences. Without these studies, documenting changes in the river habitats caused by pollutants is nearly impossible, a fact that has prevented effective enforcement of no-degradation policies in many instances. Physical baseline studies do not provide the data necessary to determine the effects of most pollutants on the most imporfant aspect of the habitat--the biota; (2) pollutant assimilative capacities of individual estuaries; (3) fish stock assessments; (4) fishery data in general, e.g., habitat and dietary preferences of major species; (5) mapping of aquiters,transmissibility of confining layers, and movement of water within the aquifers; (6) ground water pollution into estuaries, (7) effects from acid rain; (8) local impacts of rising sea level. 8.3 The Panhandle Tomorrow Population growth and development and the environment should not be competing forces because they are different parts of one ecosystem. Florida Panhandle growth must be carefully integrated into the ecosystem or undesirable repercussions are certain to occur. The Panhandle is coming under increasing growth pressures as the population influx to Florida continues and overcrowdlng in many south Florida areas decreases the desirability of living there (Figure 94). The justifiably famous white sand beaches ofthewestern Panhandle have so tar borne the brunt of the development. Belated local and State efforts to control and plan forthisgrowth (e.g., the Resource Management Committees in the Choctawhatchee and Pensacola Bay Systems) are meeting with limitedsuccess, but many ofthefactorswhich makethis region attractive have been severely damaged. Development of most of the barrier islands and beach areas is already far along. Regulation of
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Panhandlo ~cologii growth has been hindered by local groups and governments who see the financial rewards of develop ment as a quick solution to their economic wants or needs. Other parts of the Panhandle will be coming under increasing growth pressure. We hopethat the growth management legislation recently adopted by the State Legislature and presently being fine tuned and put into action will work to direct growth in a manner minimizing Panhandle environmental damage. Efforts should be made to protect the estuarine resourcesof the State as soon as possible. Appmximately 90% of all fish species in Floiia coastal waters spend at least a portion of their lives in estuaries. This use can be related directly to commercialandsportfishingdollars. Economicdevelop ment can become economic loss because of decreased productivity. For example, filling in marshland for development is an economic asset for afew developers while the loss of nursery habfiat and subsequent loss in fish production is an economic cost which the general public pays. Maintenance of the fishing sport and industly which attract many people to the coastal region requires that estuarine resources not be bst and that fisheries data (e.g., stock assessments, habitat preferences, etc.) on which to base management decisions be collected. Areas within the Panhandle which are most sensitive to development and where it should be prevented or minimized include: (1) river floodplains; (2) coastal wetlands; (3) barrier islands and nonwetland coastal areas where damagefromthe rising sea levelandfrom storms is probable (i.e., most areas within a few hundred meters of the water); (4) estuaries still in good condition (e.g., Apalachicola Bay, Choctawhatchee Bay, St. Joseph Bay). Subtial seagrass beds within the various Panhandle estuaries, as well as along the coast, should be protected and preserved to the fullest extent possible. Areas which can suppolt development if care is used to address ecological "Achilles' heels" include: (1) Majoraquifer recharge areas (e.g., large partsof Jackson and Washington Counties); (2) Areas where ground water is easily contaminated (studies are underway to help define these areas; they are likely to include much of the Panhandle). Panhandle areas with unique properties that should be preserved for the future include: (1) seagrass beds; (2) salt marshes; (3) oldgrowth forest types, including the longleaf ~ineforest on Eolin Air Force Base. the stunted cypress forest on clay soils in the western hall of the Apalachicola National Forest, and floodplain hardwood forests; (4) steephead areas along Econfina Creek and the Choctawhatchee River; (5) caves in the Marianna Lowlands, particularly those providing access to ground water filled passages and the various aquatic cave species. Few of thecaves within MariannaCaverns State Park provide this access. In addtion to these unique areas, we suggest that locations of the more important common habitat types be identified and that habitat preserves be set aside for each. There is a tendency to overlook the commonwhile it is beingdeveloped, only to find later that what wasonce commoncan no longerbefound, or is found with so many changes that it isfunctionally dierent.
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LITERATURE CITED Abele, L.G. 1970. The marine decapod crustacea of the northeastern Gulf of Mexico. M.S. Thesis. Florida State University, Tallahassee. 136 pp. Abele, L.G., and W. Kim. 1986. An illustrated guide to the marine decapod crustaceans of Florida. Fla. Dep. Environ. Regul. Tech. Ser. 8(1). 760 pp. Ager, L.A., C.L. Mesing, R.S. Land, M.J. Hill, M. Spelman, and R. Simmons. 1983. Annual report for fisheries ecology and dredging impadson the ApalachicolaRiver System. Fla. Game Fresh Water Fish Comm., Tallahassee. 123 pp. Akers, W.H. 1972. Planktonic foraminifera and biostratigraphy of some Neogene formations, northern Florida and Atlantic Coastal Plain. Tulane Stud. Geol. Paleontol. 9: 1-1 40. Akin, R.M., and H.J. Humm. 1959. Macrocallistanimbosa at Alligator Harbor. Q. J. Fla. Acad. Sci. 22: 226-228. Alvis, C.A. 1971. Trophic relationships between significantly associated species of macrobenthos in the shoal grass habitat. M.S. Thesis. Florida State University, Tallahassee. 97 pp. Anderson, W. 1975. Temperature of Florida streams. Revised Edition. U.S. Geol. SUN. Map Ser. No. 43. Applegate, A.V., F.A. Pontigo Jr., and J.H. Rooke. 1978. Jurassic Smackover oil prospects in the Apalachicola Embayment. Oil Gas J. 76(4): 80-84. Applin, P.L. 1951. Preliminary report on buried preMesozoic rocks in Florida and adjacent states. U. S. Geol. SUN. Cir. 91 : 1-28. Applin, P.L., and E.R. Applin. 1944. Regional subsurface stratigraphy and structure of Florida and southern Georgia. Am. Assoc. Petrol. Geol. Bull. 28: 1673-1753. Arden. D.D. 1974. A geophysical profile in the Suwannee basin, northwestern Florida. Ga. Geol. Surv. Bull. 87: 111-122. Aska, D.Y., and D.W. Pybas. 1983. Atlas of artificial reefs in Florida. Florida Sea Grant College MAP-30. 15 pp. Atkinson, G.D., and J.C. Sadler. 1970. Mean-cloudiness and gradient-level-wind charts over the tropics. Air Weather Sew. Tech. Rep. 215. U.S. Air Force. Scott Air Force Base, 111. 37 pp. Auffenberg, W., and R. Franz. 1978. The status and distribution of the gopher tortoise (Gopherus polyphemus). Pages 95-126 in R.B. Bury. ed. North American tortoises: conservation and ecology. U. S. Fish Wildl. Sew.. Wildl. Res. Rep. 12. Babcock. S.C. 1977. Lakes Talquin and Jackson investigations; study II: Lake Jackson studies. DingelMohnson Proj. F-31-3 (mimeo). Fla. Game Fresh Water Fish Comm., Tallahassee. Babcock, S.C., and R.W. Rousseau. 1978. Lake Talquin and Jackson investigations; study II: Lake Jackson studies. DingellJohnson Proj. F-31-4 (mimeo). Fla. Game Fresh Water Fish Comm., Tallahassee. 81 pp. Bahr, L.M., and W.P. Lanier. 1981. The ecology of intertidal oyster reefs of the Southern Atlantic coast: a community profile. U.S. Fish Wild. Sew. FWSIOBS-811 15. 105 pp. Banks, J.E., and M.E. Hunter. 1973. Post-Tampa, pre-Chipola sediments exposed in Liberty, Gadsden, Leon, and Wakullacounties, Florida. Trans. Gulf Coast Assoc. Geol. Soc. 33: 355-363. Banks, T. 1983. The hydrologic effects of the removal of the Dead Lakes dam. Northwest Fla. Water Manage. Dist., Havana. Fla. Tech. File Rep. 9 pp. Banks, T., A.E. Maristany, J.R. Wagner, and M. Flemming. 1983. Inventory of water resources data and literature forthe Apalachicola River basin, Florida. Northwest Fla. Water Manage. Dist., Havana, Fla. Water Resour. Spec. Rep. 83-7. 207 pp. Barada, W.R. 1982. The St. Johns River: an environmental time bomb. Pages 1-8 inEnfo report 82-2. Fla. Consew. Found., Winter Park. Barnett, R.S. 1975. Basement structure of Florida and its tectonic implications. Trans. Gulf Coast Assoc. Geol. SOC. 25: 122-142. Barnett. T.P. 1983. Global sea level: estimating and explaining apparent changes. Pages 2777-2795 in
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Panhandle Ecological Characterization O.T. Magoon, ed. Coastal Zone '83. American Society tions of those regions, together with observations on the of Civil Engineering, New York. manners of the Indians. Philadelphia: James and JohnBarr, D.E. 1983. Ground-water conditions in the vicinity ''' pp. of Choctawhatchee Bay, northwest Florida. Northwest Bass, D.G., Jr. 1983. Study Ill: Rivers of Florida and their Fla. Water Manage. Dist., Havana, Fla. Water Resour. fishes. DingellJohnson project F36. Florida Game Spec. Rep. 83-1 0. 46 pp. Fresh Water Fish Comm., Tallahassee. 397 pp. Barr, D.E., and E. Bowman. 1985. Results of Bass, D.G., and V. Hin. 1978. Sportfishery ecology of the ground-water nutrient monitoring at wastewater percoEscambia River, Florida. Fla. Game Fresh Water F~sh lation ponds in Destin, Florida. Northwest Fla. Water Comm., Tallahassee. 66 pp. Manage. Dist., Havana, Fla. Tech. File Rep. 85-1. 24 Bass, M.N. 1969. Petrography and ages of crystalline PP. basement rocks of Florida, some extrapolations. Am. Barr, D.E., and T. Pratt. 1981. Results of aquifer test and Assoc. Petrol. Geol., Mem. 1 1: 283-31 0. estimated drawdowns in the Floridan aquifer, northern Banisti, D.s., and A.J. Clarke. 1982. ~~ti~~ti~~ of nearCounty, northwest Florida. Northwest Fla. Water shore tidal currents on nonsmooth continental shelves. Manage. Dist., Havana, Fla. Water Resour. Spec. Rep. J, ~~~~h~~. R~~, 87(~9): 7873-7878, 81 -1. 38 pp. Beccasia, A.D., N. Fotheringham, and A.E. Redfield. Barr, D.E., and J.R. Wagner. 1981. Reconnaissance of 1982. ~ulf coast ecological inventory: users guide and the ground water resources information base. U.S. Fish Wildl. Serv. Biol. Serv. Prog. C~~nty. Northwest Fla. Water Manage. Dist., Havana, FWS/OBS-82/55. 191 pp. Fla. Tech. File Rep. 81-8. 28 pp. Beck, W.M., Jr. 1965. The streams of Florida. Bull. Fla. Barr, D.E., A. Maristany, and T. Kwader. 1981. Water state M~~. 6iol. sci. 10(3): 91-126. resources of southern Okaloosa and Walton Counties. northwest Florida: Summary of investigation. NorthBeem, K.A. 1973. Benthonicforaminiferapaleoecology of west Fla. Water Manage. Dist., Havana, Fla. Water the ChOctawhatchee (Neogene) Resour. Assess. 81-1. 41 pp. Florida. Ph.D. Dissertation. University of Cincinnati, Ohio. 201 pp. Barr, D.E., L.R. Hayes, and T. Kwader. 1985. Hydrology of the southern parts of 0kaloosa and walton counties, Bell, C.K. 1979. Nitrogen fixation (acetylene reduction) northwest F~~~~~~, with special emphasis on the upper associated with seagrasses along the northern Florida limestone of the Floridan aquifer. U.S. Geol, Surv. Gulf coast. M.S. Thesis. Florida State Univers~ty, Water Resour. Invest. Rep. 84-4305. Tallahassee. 66 Tallahassee. 76 pp. PP. Bell, P. 1980. Volcanic ash could mask global CO, effect. Barraclough, J.T., and O.T. Marsh. 1962. Aquifers and EOS* Trans. Am. Geophys. 61(29): 537. quality of ground water along the gulf coast of western Bender, M. 1971. The reliability of HeN dates on corals. Florida. U.S. Geol. SUN., Rep. Invest. No. 29. TallaAm. Geophys. Union Trans. 52(4): 366. hassee. 28 pp. Berner, L. 1950. The mayfliesof Florida. Univ. Fla. Publ.. Barrett, Daff in and Carlan, Inc. 1982. Regional water Biol. Sci. Ser. 4(4): 1-267. S~W'Y plan: forcoastalareasof northwest Best, G.R., L,N, Schwartz, L. Sonnenburg, S. Kidd, and Florida. Northwest Fla. Water Manage. Dist., Havana, J,J. M~c~~~~~. 1983. L~~-~~~~~~ wastewater recyFla. 205 pp. cling through wetland ecosystems: Apalachicola Bartel, R.L. and J.D. Barksdale. 1985. Hydrogeologic study--experimental use of a freshwater shrub swamp, assessment of solid waste landfills in northwest Florida. summary progress report. Cent, Wetlands Rep. NO. 39. Northwest Fla. Water Manage. Dist., Havana, Fla. univ. Florida. 105 pp, Water Resour. Spec. Rep. 85-1. 104 pp. Bittaker, H.F., and R.L. Iverson. 1976. Thalassia tesEarth, M.C., and J.G. Titus. 1984. Greenhouse effect and tudinum pro~uct~v~ty~ a field of measuresea level rise. Van Nostrand Reinhold Co., New York. ment methods. Mar. Biol, 37: 3946. 325 pp. Borror, A.C. 1961. Morphology and ecology of the benthic B~~~;n~G~~~~, e~~~~~~~~~ri~,",~",,"~~~,"~~~ ciliated protozoaof Alligator Halbor Ph.D. Dissertation. country, the extensive territories of the Muscogulges or Florida State University' Tallahassee. 67 pp' Creek Confederacy, and the country of the Choctaws: Bortone, S.A. 1976. Effects of a hurricane on the fish Containing an account of the soil and natural producfauna at Destin, FL. Fla. Sci. 39: 245-248. 250
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Panhandle Ecological Characterlzatlon Wood, D.A. 1983. Red-axkaded woodpecker symposium ICPmceedings. Florida Game and Fresh Water Fish Commission, Tallahassee, Florida. 112 pp. Wood, D.A. 1986. Official lists of endangered and potentially endangered fauna and flora in Florida. FloridaGame and Fresh Water Fish Commission. Tallahassee. 19 pp. Woodin. S.A. 1978. Refuges, disturbance, and mmmunity structure: A marine soft-bottom example. Ecology 59: 274-284. Woods, G. 1957. Factors limiting root penetration in deep sands of the southern coastal plain. Ecology 38: 357-359. Wooley, C.M.. and E.J. Crateau. 1982. Observation of Gull of Mexico sturgeon (Acipenser oxyrhynchus desoto4 in the Apalachicola River, Florida. Fla. Sci. 45: 244-248. Yentsch. C.S. 1953. Some of the factors influencing distribution of sessile invertebrates in Alligator Harbor, a neutral estuary. M.S. Thesis. Florida State University, Tallahassee. 64 pp. Yerger. R.W. 1965. The leatherback turtle on the gulf coast of Florida. Copeia 3: 365-366. 1977. Fishesof theApalachicolaRiver. Pages 22-33 in R. J. Liiingston and E. A. Joyce. Jr., eds. Proceedings of the conference on the Apalachimla drainage system 23-24 April 1976, Gainesville, Florida. Fla. Mar. Res. Publ. 26. Yon, J.W. 1966. Geology of Jefferson County, Florida. Fla. Geol. SUN. Bull. 48: 1-1 19. Young, F.N. 1954. The water beetlesof Florida. Univ. Fla. Publ., Biol. Sci. Ser. 5(1): 1-238. Zieman, J.C. 1975. Tropical seagrass ecosystems and pollution. Ch. 4 inE.J.F. Wood and R.E. Johannes eds. Tropical marine pollution. Elsevier Oceanogr. Ser. 12. Elsevier Publ. Co., New York 1976. The ecological effectsof physical damage from motorboats on turtle grass beds in southern Florida. Aquat. Bot. 2: 127-139. 1982. The ecology of the seagrasses of south Florida: acommunity profile. U.S. Fish Wildl. Sew. Off. Biol. Sew. FWSK)BS-82/25. 150 pp.
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Appendix A FEDERAL, STATE, AND LOCAL ENVIRONMENTAL CONTROL AGENCIES AND THEIR RESPONSIBILITIES Federal Agencies I. Amy Corps of Engineers Concerned with all activities which affect or modify navigable waters of the United States. Primarily concerned with construction in navigable waters and with dredge and fill permits. They are also involved in permitting the placement of dredge and fill material into navigable waters and adjacent wetlands, and they provide some funding for aquatic plant control in navigable and public waters. 2. Coast Guard They have authority to respond in an ernergency to hazardous waste releases and to force responsible parties to clean up. 3. Department of Commerce-Natlonal Oceanic and Atmospheric Adminlstratlon The administrator of NOAA is currently directing a ten-year effort to develop and implement a program to deal with acid precipitation. 4. Environmental Protection Agency This is the main Federal agency responsible for "clean water." Areas covered by EPA include: hazardous waste cleanup, public drinking water systems, all point-source pollutant discharges into waters of the United States, and protection and restoration of the environment. EPA also reviews Corps of Engineers permit activities, and sets guidelines for State environmental programs. Corpsof Engineers' permitsfor effect on fish and wildlife, and managing all Federal public lands. Under this department the U.S. Geological Survey conducts research on water resources and the U.S. Fish and Wildlife Service manages and restores sport fish and wildlife populations and conducts researchon the effects of pollution on fishery and wildlife resources. The Mineral Managements Service is responsible for the regulation of oil and gas wells on the Outer Continental Shelf. 6. Department of Agrlculture The Soil Conservation Service promotes the use of conservation practices to reduce soil losses, including techniques to reduce runoff and thus improve water quality in waterways. The U.S. Forest Service promotes watershed management, wildlife habitat management, and reforestation programs. The Agricultural Stabilization and Conservation Service, through many programs, helps protect wetlands and helps solve water, woodland, and pollution problems on farms and ranches. Florida Agencies 1. Department of Agriculture and Consumer Services This department regulates the purchase and use of restricted pesticides and helps in soil and water conservation through activities of the Soil and Water Conservation Districts and the Division of Forestry. 5. Department of Interior 2. Department of Community Affairs Functions performed by this agency include This department is responsible for reviewing reviewing proposed activities which impact local comprehensive plans and has jurisdiction threatened or endangered species, reviewing over "Developments of Regional Impact" (DRI).
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Panhandle Ecologlc al Characterization These concern developments which could have a substantial effect upon the health, safety, or welfare of citizens of more than one county. Department of Environmental Regulation The DER is the lead agency involved in water quality, dredge and fill, pollution control, and resource recovery programs. The department sets water quality standards, pollution discharge loadings, and has permit jurisdiction over pointand nonpoint-source discharges, dredge and fill, drinking water systems, powerplant siting, and many construction activities in waters of the State. The department also interacts closely with other Federal and State agencies on water related matters. 4. Florida Game and Fresh Water Fish Commission The purpose of the Commission is to manage, protect, and conserve wild animal life and freshwater aquatic life. Its efforts include sport and commercial fishing, fishery and habitat management, lake drawdowns, and fish and wildlife stocking. 5. Department of Health and Rehabllltative Services HRS is responsible for septic tank system permitting through its county health departments, mosquito control coordination, and investigations into threats to the public health. 6. Department of Natural Resources The DNR is highly involved inwaterrelatedproblems. Besides administering all State lands, including parks and aquatic preserves, DNR serves as the enforcement agency for the Florida Endangered and Threatened Species Act and the Oil Spill Prevention and Pollution Control Act. DNR is also responsible for coordinating aquatic plant research and control in the State. DNR issues permits for transport of aquatic plants, herbicide spraying, and other plant control methods in aquatic environments. DNR also has lake management extension services. Other Agencies 1. Water Management Distrlcts The five multipurpose water management districts in the State are concerned with water use, lake levels, dredge and fill, water quality, and other water-related management programs. These districts can hold, control, and acquire land and water bodies which affect water storage. 2. Reglonal Plannlng Councils The 11 regional planning councils in the State act in an advisory capacity to local governments in matters concerning water resources, recreational areas, and Developments of Regional Impact. 3. Soil and Water Conservation Districts These districts are supervised to a limited degree by the Department of Agriculture and Consumer Services and carry out preventive measures for flood prevention and soil erosion. 4. Miscellaneous Many local counties and municipalities have environmental and planning agencies which can be involved in environmental management. Local governments can also pass pollution control laws, zoning and land use laws, and many other ordinances which can be effective in preventing environmental problems. Many of these agencies perform functions which overlap on the State, Federal, and local level. There are also many Memoranda of Understanding between agencies which allow sharing of overlapping functions. Local, State, and Federal agencies interact extensively on programs because of mutual benefits and cost sharing agreements.
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Appendix B PANHANDLE REGULATORY AGENCY LOCATIONS AND ADDRESSES Florida Department of Environmental Florida Game and Fresh Water Fish Regulation: Commission Main Office Main Office 2600 Blair Stone Rd. 620 S. Meridian St. Tallahassee, FL 32399-2400 Tallahassee, FL 32399 (904) 488-4805 (904) 488-1 960 Northwest District Office Northwest Regional Office 160 Governmental Center Rt. 4, Box 759 Pensacola, FL 32399-3000 Panama City, FL 32405 (904) 436-8300 (904) 265-3676 Florida Department of Natural Northwest Florida Water Resources-Regional Biologists Management District Northwest Region Rt. 1, Box 31 00 3900 Commonwealth Blvd., Rm. 304 Havana, FL 32333 Tallahassee, FL 32304 (904) 487-1 770 (904) 488-5631 U.S. Army Corps of Engineers Panama City Field Office P.O. Box 151 Panama City, FL 32401 (904) 785-9366 Regional Planning Councils @West Florida RPC @ Apalachee RPC P.O. Box 486 P.O. Box 428 Pensacola, FL 32593 Blountstown, FL 32424 (904) 674-4571
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50272 -101 I An Ecological Characterization of the Florida Panhandle *Also known as OCS StudyfMMS 88-0063 16. Abstract (Limit: 200 words) --The Florida Panhandle extends from the Ochlockonee River basin west to the FloridaAlabama border and north to the Georgia and Alabama borders; it contains some of the most rapidly developing legions in the entire State. Because of the damaging effects of development, some attention must be given to the region's estuaries, coast, wetlands, and to habitats of endemic species. Development has already damaged some of these areas as well as the seagrass beds and oyster reefs of the western panhandle area. Other potentially affected areas include native upland ecosystems, salt marshes, river floodplains, and steephead areas. Research, growth management legislation, and consideration of the Florida Panhandle ecosystem as a whole are all necessary to ensure the futures of the different Florida Panhandle areas. No steps can be taken or decisions made for their longevity until certain data gaps are filled; the gaps range from biological baseline studies of 3. Recipient's Accession No. 5. Report Date October 1988 6. -7. Author(~) Steven H. wolfea Jeffre A. ~eidenauer~ and D. Bruce ~eans~ 9. AU t hor sA~T-I-O~ s a~tate of Florida b~oastal Plains Institute Department of Environmental Regulation 131 3 N. Duval Street 2600 Blair Sfone Road Tallahassee, FL 32399 Tallahassee,FL 32399-2400 12. Sponsoring Organlration Name and Address National Wetlands Research Center USDI, Minerals Mgmt. Servic?' Fish and Wildlife Service Gulf of Mexico OCS Region estuaries to the local impacts of rising sea level. 2. REPORT DOCUMENTATION PAGE 8. Performing Organ~zat~on Rept NO 10. Pro~ectlTasklWork Unst No. 11. Contract(c) Or Grant(G) No to (G) 13. Type of Report 6 Per~od Covered -1 h ldentlfienmpen.Ended Terms 4. Title and Subtitle 1. REPORT NOBiological Report 88(12)* estuaries development seagrass beds habitats floodplains growth management legislation salt marshes endemic species Florida Panhandle ecosystem bogs U.S. Department of the Interior 1201 Elmwood Park Blvd. Washington. DC 20240 New Orleans, LA 70123-2394 14. I Unlimited Release IS. Supplementary Notes c. COSATI Field/Group I / Unclassified (See ANSI-239.18) See Instructions on Reverse OPTIONAL FORM 272 (4 18. Availability Statement (Formerly NTIS-35) Department of Commerc -19. Security Class (This Report) 21. No. of Pages
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DOCUMENT : MARSTON SCIENCE LIBRARY
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As the Nation's principal conservation agency, the Department of the Interior has responsibility for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, orotectina our fish and wildlife, ~reservina the environmental and ciltural values of our national parksand historical olaces. and orovidina for the eniovment of life through outdoor'recreation. ~h6 ~e~artmeit assesses our energy and mineral resources and works to assure that their development is in the best interest of all our people. The Department also has a major responsibility for American Indian reservation communities and for people who live in lsland Territories under U.S. Administration.
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