|
Sirenews a
newsletter r of the 9vCc'/SS C
Strenia Specfalist group
NUMBER 3 APRIL 1985
IN THIS ISSUE: PALAUAN DUGONGS APPEAR DOOMED TO EXTINCTION
(p. 7)
RECORD MANATEE MORTALITY IN FLORIDA (p. 5)
EDITORIAL: WHY SAVE SIRENIANS?
My last editorial brought a response from a colleague who
asked whence I derived the obligation I mentioned to set aside
sufficient of this planet's space and resources for the survival
of other species. "I've sought in vain," he writes, "for a really
convincing answer (other than my own personal pleasure and
interest).... Can you come up with a scientifically,
economically, or philosophically defensible argument that would,
for example, place survival of manatees in Florida ahead of
*economic growth" when it comes to the bottom line? Or one that
would argue that a starving village should spare the last African
manatees?"
A challenge like that cannot be evaded; it is THE challenge
that the Sirenia Specialist Group, and conservationists in
general, face. I will attempt an answer, and welcome any better
ones that others can offer.
UNION INTERNATIONAL POUR LA CONSERVATION DE LA NATURE ET OE SES RESOURCES
INTERNATIONAL UNION FOR CONSERVATION OF NATURE ANDO NATURAL RESOURCES
Commission deo la sauvegarde des espces-Species Surviva Commission
Sirenews is edited by Daryl P. Domning, Dept. of
AnItomy, Howard University, Washington, D.C,
20059 USA. It is supported by the Species Survival
Commission of IUCN, the U.S. Fish and Wildlife
Service, and the U.S. Marine Mammal Commission.
As with any wild species, many more or less pragmatic
reasons for preserving sirenians can be given. I list these
roughly in order of their increasing importance to increasing
numbers of humans:
1. EQZd. The most tangible value of sirenians is also the
one which can benefit most people the least. By eating an animal
we cash it in at the lowest rate of exchange; as with a bond
cashed before maturity, there is a severe interest penalty to
pay. All its other potential dividends are forfeited. It may be
that every part of the carcass is used; the proceeds may fill the
stomachs of a subsistence hunter's family or help keep alive the
traditions of an ancient culture. Or they may undermine those
same traditions by increasing dependence on a cash economy. In
any case, the long-term good of the greater number is sacrificed
to the immediate needs of a small fraction of the nation's
population. Nowhere can this provide a solution to mass hunger,
even if entire species are annihilated. Clearly, only very
limited hunting of sirenians can be tolerated in the foreseeable
future.
2. fend Control. Often discussed but yet to prove practical
on any significant scale, the use of manatees in clearing weed-
choked canals and reservoirs is still worth exploring. Aquatic
weeds are an economic curse throughout the tropics, and a safe,
cheap form of biological control would benefit millions of
people. It would also allow multiple use of the manatee resource,
but the severe limitations to its applicability scarcity of
sirenians, vulnerability of impounded animals to poaching, and
less than complete weed removal must be acknowledged.
3. TQuiimsh EducaLiQnA and eassachb. Under unusual
circumstances, such as clear-water springs in Florida, wild
sirenians can be economically significant local tourist
attractions while remaining part of their ecosystems. Captive
animals can entertain and edify larger numbers of people,
a function probably well worth the price of their contributions
as wild animals to the larger environment. The results of
scientific research on all living species enrich human culture
just as do contributions to the other sciences, arts, and
humanities.
S 4. ECQIi.acal Yalue. In this part of the use spectrum,
. direct user impact on wild sirenian populations is minimal and
gains are diffuse and not immediately obvious, but the benefits
may in fact be very broad. For example, the role of sirenians in
the nutrient cycles of seagrass communities and blackwater
tropical rivers could be of significant benefit to fisheries.
Aquatic plant communities, as a component of which sirenians
evolved and to which they may be important, are both extremely
productive and capable of absorbing large quantities of
pollutants. More generally, all humanity has an important stake
in the health of all ecosystems, which buffer us from the effects
of our own mistakes. In this sense every species is a line of
defense between ourselves and natural or unnatural disaster.
Since we have hardly begun to understand these relationships,
prudence dictates the protection of major ecosystem components
such as sirenians.
5. genatiC Yalue. Genetic engineering will revolutionize
civilization in the twenty-first century as computers did in the
twentieth, and genetic resources will be as valued as petroleum
is today. By that time, unfortunately, the developing tropical
nations will have allowed much of their great wealth of
biological diversity to be wiped out, thereby squandering what
may be their last chance to escape permanent poverty and economic
impotence. But the genetic value of sirenians and most other
species is still as imponderable today as was the future worth of
petroleum in 1785.
6. A&sthbtic Yalue. Aesthetic appreciation of wildlife is a
luxury of the "developed" world, a pleasure to be indulged after
the children are fed. But if we claim to hope for a day when all
people enjoy this luxury, must we not ensure there is something
left to enjoy when that day comes?
7. 8L.11 Yaluh There are some things for which civilized
people do not demand economic justification. Heroic medical
treatment is given, at frightful cost, to terminally ill and even
congenitally retarded individuals regardless of any monetary
value their lives might have to society. Aid is sent to starving
Africans, not with a view to anticipated return, but because they
are starving. Humane treatment of animals is mandated by law
because it is deemed right, even if it costs more. Some people
oppose some or all of these efforts, and those who support them
do so for varied religious and ethical reasons. But there is
clearly a consensus that some things ought to be done, and the
list of moral desiderata has grown over the centuries. Slaves
should be freed, torture should be outlawed, and species should
be preserved from extinction. Whether there has been any net
moral progress in human history is debated, but if (as I believe)
there has, these are its milestones. To borrow a recently current
phrase, our institutions and our generation will be judged by how
well they protect the powerless; and sirenians, like all other
species, are surely now in our power.
In his recent book iagDbilia, E. 0. Wilson stresses the
innate affinity of man with other living things, and the
fundamental connection between the value we place on them and the
value we place on ourselves. "The phylogenetic continuity of life
with humanity," he writes, "seems an adequate reason by itself to
tolerate the continued existence of ... other organisms. This
does not diminish humanity it raises the status of nonhuman
creatures." But there is a deeper reason: "...we are human in
good part because of the particular way we affiliate with other
organisms. They are the matrix in which the human mind originated
and is permanently rooted...." Other species are part of our own
fabric in ways we do not suspect. Our nerve fibers do not extend
into their substances we feel no physical pain when they are cut
off from the tree of life. But we are diminished by it all the
same. Without them we will never be fully human.
Economic growth? To be sustained, it must be farsighted, and
destruction of species and ecosystems is one of the more
dangerous forms of myopia. World hunger? It will never go away
until we control our population, even if we consume all else and
begin eating each other. The "bottom line"? It is our
responsibility to foresee and fgnrstall those ultimate
confrontations between nature and developers, between wildlife
and starving villagers, by finding creative ways for wildlife to
earn its keep and by adopting a sufficiently broad and wise view
of its values) to us. Responsible stewardship? We are the
stewards of this planet, and will be held accountable by
posterity and by whatever higher authority we acknowledge. I find
those reasons convincing. Do you? DPD
LOCAL NEWS
BRAZIL
Robin Best writes the following under date of 27 Feb. 1985:
"My present position is drastic as we still have no funding
and to keep us employed we are doing faunal surveys for [the
electrical power agency] ELETRONORTE with all manatee work on
hold. ... If I ... leave the whole thing will collapse as I doubt
that anyone here will push to finish the new pools etc. ...
Through these hydroelectric projects I've contracted four more
people so we've got the best potential ever to do the work but
the international apathy doesn't help. ... Time is running out
fast.... The desperate writing of projects etc. has slowed down
my own production drastically.... Amazdnia continues to be
threatened as the [present] State Governor is all for the
commercial utilization of wild game and the hydroelectric group
(ELETRONORTE) have plans for some 200 dams in the area
Colonization and agriculture continue taking their toll! My
salary was Cr$9.500 in 1976 and the dollar was Cr$9. Today at
2,400,000 with the dollar at Cr$4200 our salaries are less than
half of what they were which doesn't help keep one enthused about
staying here under adverse conditions"
FLORIDA
J.P. Garner, Jr., Director of Nature World in Homosassa
Springs, writes under date of 17 December 1984:
"At the present time we have four captive West Indian
manatees in a natural area here at Nature World on the Homosassa
River. Two of the animals are juveniles recently transported here
from Miami Seaquarium. We also house one adult pre-act [Marine
Mammal Protection Act of 19721 female and one adult post-act
male. These animals are in an area [of the Homosassa River] which
is fenced with vertical bars spaced eight inches apart. They can
actually have nose to nose contact with the wild manatee which
naturally winter here....
"As of December 10, 1984, the County (Citrus County)
purchased this facility so as not to let it fall into the hands
of developers. Our Board of County Commissioners has expressed
their thought as to keeping this place as natural as possible.
The County Operations Committee is also interested in this
natural facility being used for manatee research and
breeding...."
The following items were contributed by the Gainesville lab:
Hanatee gitality. 1984 ended with the highest number of
manatee deaths in one year: 131 deaths were documented. One
manatee was recovered from Puerto Rico, one from Georgia, one
from North Carolina, and 127 from Florida. An additional manatee
death in Florida was verified but the carcass was not examined.
Necropsy results yielded the following numbers of cases in each
death category: boat or barge collision, 35; crushed or drowned
in floodgate or canal lock, 3; other human-related, 1; dependent
calves, 26; natural 25; undetermined, 40.
The total number of manatee deaths in January and February
1985 was 35, which was less than the January and February 1984
total of 49. Three of the 35 carcasses were recovered from Puerto
Rico and one from South Carolina. The causes of death and number
of cases in each category were: boat or barge collision, 5; other
human-related, 3; dependent calf, 1; natural, 11; undetermined,
14; and one carcass was verified but not recovered.
SaJyaga Sighlighbt. The two largest manatees ever recorded
were recently recovered in Florida. A pregnant female that was
struck by a boat was collected in November 1984 from Hendry
County. She was 376 cm in length and weighed a record 1401 kg.
Manatees get even larger, though. In February 1985 a 375 cm, 1620
kg female was recovered from Crystal River in Citrus County. She
had also been hit by a boat. This case was particularly
unfortunate, as she was a well-known female with a reproductive
history going back to 1977.
[EDITOR'S NOTE: Gunter (1941) recorded a male T aat
said to have been 15 feet 3 inches (465 cm) long and weighing
1310 pounds (595 kg). However, his information was received at
third hand and these figures may well have been garbled.]
adi-tracking ErQi~ct. During the passage of a cold front
on 7 January 1985, personnel of the Denver Wildlife Research
Center (DWRC) Sirenia Project captured 20 West Indian manatees in
Fort Myers, Florida. Sixteen of these animals were fitted with
newly designed floating radio transmitters, which were developed
in cooperation with the DWRC electronics personnel. The floating
transmitters are tethered to a belt around the peduncle with a
six-foot-long nylon rod. The one-day-long capture was the most
successful manatee capture and tagging operation ever undertaken
in Florida and was made possible by the cooperation of personnel
from several agencies and organizations, including the J. N.
"Ding" Darling National Wildlife Refuge, the Florida Power and
Light Company, Lee County Parks and Recreation, the Florida
Department of Natural Resources, the Department of Wildlife and
Range Sciences of the University of Florida, and several
volunteers. The radio-tagged manatees will now be tracked during
the next year to determine areas of special importance to this
endangered marine mammal. This radio-tracking project has taken
on even greater importance recently because several artificial
warm-water refuges that are used during the winter by manatees,
including the Fort Myers Power Plant, have been altered. By
following the radio-tagged manatees, vital information on
movement patterns in relation to warm water (or lack of warm
water) will be gathered.
In 1979 a cold-stressed male West Indian manatee was rescued
near Gulfport, Mississippi and rehabilitated at oceanaria in
Florida. In captivity this manatee, named "Beauregard", was used
to develop a method of attaching radio-frequency transmitter
packages for tracking free-ranging animals in saltwater habitats.
In February 1985 the manatee was released into the Homosassa
River on the central west coast of Florida with a satellite PTT
(platform terminal transmitter) tag. The unit consisted of a
modified Telonics wildlife PTT and battery pack capable of
powering the unit for 60 days, housed in a floating cylinder
attached to a 2-meter-long tether secured to a belt around the
peduncle. Transmitted data included internal PTT temperature and
the cumulative changes in the attitude of the housing. Two polar-
orbiting satellites, each carrying ARGOS Data Collection System
packages, were used to monitor the signals. Location of the
animal could be calculated as often as nine times per day. During
the first week of tracking, nearly 20% of the satellite
overpasses resulted in location fixes and over 50% resulted in
reception of data. The manatee travelled about 75 km to the mouth
of the Suwannee River during this time.
HalicX -tL CiQQPrEatiQD. The Sirenia Project recently was
host to a biologist from the Mexican Government. From 10 February
through 2 March 1985, Manuel Vasquez visited various field sites
and offices in Florida to learn more about research techniques
currently being used to study manatee biology. The status of
manatees in Mexico was also discussed during the visit, and it is
hoped that Manuel's visit will eventually lead to other
cooperative manatee work between Mexico and the US.
Staff ChbaDg3. On 3 February 1985 Dr. Thomas J. O'Shea
became Project Leader of the U.S. Fish and Wildlife Service's
Sirenia Research Project. This change was brought about due to
Dr. Galen Rathbun's transfer to the Service's California Sea
Otter Research Project. Although Galen's principal duties will be
related to sea otter research, he will remain active with various
manatee and dugong research projects overseas. Dr. Lynn Lefebvre
will be transferring to the Sirenia Research Project this summer.
Lynn currently works for the Service's animal damage control
research facility in Gainesville.
Another recent change in the staff of the Sirenia Research
Project was brought about due to funding cuts to the project and
the expanded role the State of Florida is playing in manatee
conservation. Kipp Frohlich, who has done carcass salvage and
radio-tracking work for the project in the Fort Myers area for
the last 18 months, has transferred to the Florida Department of
Natural Resources. Sirenia Project biologists will continue to
work closely with Kipp in Fort Myers.
ManatLa Brain Reaearch. The U.S. National Science
Foundation has awarded approximately $250,000 to a consortium of
researchers at four universities to analyze the phylogenetic
position of the Sirenia among other mammals on the basis of
neuroanatomy and DNA hybridization. Drs. J. I. Johnson, Jr.
(Anatomy Department, Michigan State University, East Lansing), J.
A. W. Kirsch, W. I. Welker (University of Wisconsin), R. L. Reep
(University of Florida), and R. C. Switzer III (University of
Tennessee) will study sectioned brains of Trichgbbug manatua to
produce a detailed microneuroanatomical analysis and atlas. This
will move the manatee brain from being one of the least-known to
one of the best-known brains of rare species. Together with the
DNA study, these data will serve to reassess phylogenetic
hypotheses previously derived from bones, teeth, and proteins.
The results will be very welcome, inasmuch as new fossil data on
sirenians and their relatives are also stimulating reevaluations
of "paenungulate" phylogeny at this time. Contributions of
appropriate material representing other sirenian species,
particularly Quggog, would no doubt be welcome.
PALAU
The following is quoted from AdminitLration Qf the Maring
mammal EQtactin &D at of 1222 January 1A 13 to Decemmbaer 312L
12231 Annual ewBrt Qg the Eiah and Wildlife Sersisea HA.
Department QL the InteriQr (1984), pp. 31-32:
"...The [U.S. Fish and Wildlife] Service has executed a
Memorandum of Understanding (MOU) with the Republic of Palau
providing for technical assistance in resource conservation. An
item in the MOU is the provision for review of research
proposals. This provision was included at the specific request of
the Republic of Palau. They do not presently have the staff to
make these evaluations or to conduct baseline studies of their
resources.
"Aerial surveys and citizen interviews designed to determine
the distribution and status of dugongs around the Island of Palau
were completed....
"Traditionally, the dugong had high cultural significance to
the Palauans, as well as affording a good source of protein. A
bracelet made from the atlas vertebra of a dugong could be worn
only by the chiefs of villages or municipalities, and as a
consequence, the dugong was effectively conserved by the chief.
At the present, the role of traditional chiefs has been greatly
diminished resulting in little protection for this species.
"Modern technology (speed boats, explosives, spear guns,
etc.) has also had a tremendous impact on the taking of this
species. The limited resources of the Republic of Palau are
insufficient to promote protection of the dugong from illegal
taking.
"Unregulated taking of the dugong has become critical. There
is substantial disagreement among Palauans and outside
researchers on the number of dugongs present in Palau. Aerial
surveys made by Brownell, Anderson, Owen and Ralls in 1977 and
1978 led them to estimate that the population consisted of not
more than 50 individuals, substantially less than estimates
offered by most local residents. Brownell et al. speculated that
even if there were 150 animals, the estimated poaching rate of 20
dugongs per year probably exceeded annual recruitment. Therefore,
the Palau dugong population could be exterminated by the end of
this century.
"Service efforts have been directed towards developing a
census methodology that is understood and accepted by the
Palauans. Without this acceptance, any results derived will be
suspect. However, this effort has not been a sustained one due to
insufficient resources. An effective methodology which
incorporates the observations and concerns of the Palauans is
essential. Unless the fragile nature of this isolated dugong
population can be clearly demonstrated to the Palauans, any
effort to promote conservation of the dugong will be virtually
ineffectual."
TRINIDAD AND TOBAGO
Geddes Hislop, a wildlife trainee in the Forest Division,
Port-of-Spain, contributed the following report:
The West Indian manatee, locally known as the "sea-cow",
used to be occasionally sighted in the Nariva Swamp, Trinidad's
largest freshwater wetland. Since the 1960's, however, reports of
manatee sightings have been so few and far between that the
species was believed extinct and the "sea-cow" was only mentioned
in fishermen's tales. In the early part of 1984 Dr. John
Bindernagel, Coordinator of a UNDP/FAO project on Natural
Resources in Trinidad and Tobago, sighted manatees in the Nariva
River both from the air and from a small boat. Later in the year
more sightings were made by Wildlife Research Officers from the
Forestry Division. Information from local residents implied that
manatees may have been in the swamp for about a year or more
before the sightings were made. This may be due to the annual
flooding of the Orinoco River, the overall nature of the swamp,
and the inaccessibility of the upper reaches of the Nariva River,
which provides an effective barrier to the curious local
fisherman. During the dry season (January to June) the swamp is
less hazardous and researchers were able to penetrate much
further than the local fishermen in order to reach manatee
feeding areas.
Research on manatee ecology in Trinidad is to begin in the
1985 dry season as part of research on endangered species. More
recent reports of sightings in the North Oropuche River are still
to be confirmed. Although the sea-cow is not harvested in
Trinidad, a further report of a sea-cow becoming entangled in a
fishing net in the North Oropuche River and subsequently being
eaten is to be investigated.
During the 1984 wet season, heavy rainstorms and flooding in
the low-lying areas of the island may have had their effect on
the manatee population, perhaps pushing them further into the
swamp itself or further upriver. This remains to be seen.
Present threats to the manatee are indirect environmental
ones such as long-term development plans that may affect swamp
hydrology/ecology.
WASHINGTON, D.C.
Daryl Domning and Lee-Ann Hayek have completed the
statistical analysis of quantitative and qualitative data on 272
manatee skulls (86 T. inunguia, 37 T1 asTiSaSDaiS, and 149 Z~.
anaiua). These are by far the largest samples ever used to
characterize the interspecific and intraspecific variation in
Trigbehhus. One preliminary conclusion is that Hatt's (1934)
nominal subspecies T am maa atua and T. WM latlnatria may have
some morphological basis after all. Using cranial osteology
alone, a specimen can. be assigned to the Florida or the Central
and South American form with at least 82% accuracy. Specimens
from the Antilles group with the latter form, as do ones from
Texas, whereas a skull from Louisiana groups with the Florida
population. This supports the conclusions of earlier writers that
manatees found in Texas have historically been summer immigrants
from Mexico, while those found on more eastern parts of the Gulf
Coast come from Florida. Therefore, continued use of Hatt's
subspecific names seems justifiable. (Incidentally, the
occasional carcasses being salvaged by the Gainesville lab from
Puerto Rico might merit special attention in this light, since
they are a source of material that seems to be genetically and
taxonomically distinct from Florida manatees.)
Yet another range extension for sirenians the earliest
records of the order in the Pacific basin have come to light
almost simultaneously on both sides of that ocean. An amateur
fossil collector working in the Late Oligocene Yaquina Formation
of coastal Oregon found the partial skull and dentition of an
unidentified small dugongid, which is currently being prepared
for study at the Smithsonian Institution. Hardly had this
specimen been recognized as a sirenian when Okazaki (1984)
reported a pair of dugongid caudal vertebrae from Late Oligocene
rocks in Kyushu, Japan! These finds antedate by several million
years the previously known Early or Middle Miocene sirenians of
Baja California and Peru, and except possibly for some rib
fragments from southern Mexico, no other sirenians are definitely
known from the Pacific Paleogene. But it appears that they had a
significant pre-Miocene history in that region which has hitherto
not been suspected, let alone explored.
SIRENIA WORKSHOP ITC IV
The following partial list of papers and posters has been
submitted for the Workshop "Sirenia: Biology and Conservation"
that will be held at the Fourth International Theriological
Congress in Edmonton, Canada, 13-20 August 1985. Additional
titles are forthcoming, with approximately eight to be submitted
by dugong researchers.
The manatee cecum. (R. L. Snipes)
Age determination in the West Indian manatee based on thoracic
flipper radiographs. (A. G. Watson)
Estimating age of young West Indian manatees, Trichghua wmanatua,
from dental layers. (A. C. Myrick, Jr.)
Distribution of manatees in Puerto Rico. (G. B. Rathbun, T. Carr,
and N. H. Carr)
Behavioral ecology of sirenians. (G. B. Rathbun and T. J.
O'Shea)**
Female-offspring behavior in West Indian manatees. (T. J. O'Shea
and S. H. Shane)
Mortality patterns in manatees from Florida. (R. K. Bonde, T. J.
O'Shea, and D. K. Odell)
The parasites of sirenians. (C. Beck, D. Blair, and G. B.
Rathbun)
Cataloging West Indian manatees in Florida. (G. B. Rathbun and J.
P. Reid)
Radio-tag attachments for Sirenia. (J. P. Reid, G. B. Rathbun,
and J. Bourassa)
Analysis of stomach contents of West Indian manatee carcasses
salvaged from Brevard and Duval Counties, Florida. (L. A.
Hurst and G. B. Rathbun)
Research program in information processing and social behavior in
captive West Indian manatees. (H. D. Woodyard)
The Sirenia: past, present, and the future? (D. P. Domning)**
Distribution, status, and conservation of manatees in Mexico. (L.
C. Colmenero R.)
Strategies for protection of non-exploited sirenian populations.
(J. M. Packard and P. M. Rose)**
Manatee response to a power plant shut-down in southwestern
Florida. (R. K. Frohlich and J. M. Packard)
A century of observations of sirenian brains. (J. I. Johnson,
Jr., R. L. Reep, and W. I. Welker)
** (These papers are invited spoken contributions.)
We look forward to a full and very interesting program, and
hope to see a large turnout of sirenian researchers at this
workshop.
RESULTS OF OPINION SURVEY
In the last issue, responses were invited to the question:
"What do you think are the Boat impgrtlnt unanswered questions
that we as scientists can ask about sirenians?" To date, only two
responses have been received.
Paul Anderson's nominations were "study of the ecology and
ethology of dugong reproduction. We have only tentative ideas as
to breeding season and the factors which may influence it and
know nothing of habitat requirements or the role of social
interaction. What environmental factors influence age at maturity
and frequency of reproductive activity in either sex? Are
reproductive activities particularly sensitive to disturbance?
Have declines in numbers been due to reproductive failure as well
as over-hunting? What roles do foraging opportunities, thermal
stress, and diet quality play in reproduction?"
Tom O'Shea answered that "the [question] that intrigues me
most comes from repeated days of following radiotagged manatees
as they swim purposefully for many km in turbid water or at
night, seemingly knowing all the correct turns, routes and
channels; from knowing the long distance resightings of
[hundreds] of km and the tracing of long annual circuits; and
from the probable long life spans of these animals. These
observations suggest that manatees must have a tremendous
capacity for learning spatial characteristics of their
environment and a remarkable memory for recall of such seemingly
detailed information over many km and years. How do they do this?
From a comparative zoological viewpoint, there may be some
extremely interesting findings to be had here in terms of sensory
perception, orientation, navigation, and learning. It would be a
very, very difficult job to try to get at these points and would
require some highly creative work. Perhaps the brain studies [see
news from Florida, above] will help begin to get us on the right
track in comprehending this. Or perhaps it's much simpler than it
seems."
For my part, I got carried away and came up with a score of
questions, divisible into physiological/anatomical, behavioral/
ecological, and evolutionary categories:
Physiological and Anatomical:
How important is animal protein in sirenian diets?
How do euryhaline manatees adapt to abrupt changes in
salinity?
Is Tichechua inunguia confined to fresh water by a lack of
salinity tolerance?
Why do sirenians have so many retia mirabilia?
Why do sirenians have bifurcated hearts?
Why do sirenians have monopodial bronchial trees?
What is the significance of sirenian bone density?
What is/are/were the functions) of dugongid tusks?
How important to sirenians are chemical senses, and how do
they work?
Behavioral and Ecological:
What are the functions of sirenian vocalizations?
How and why do females choose particular males as mates?
(Or do they?)
How ecologically typical of T, manatus are Florida manatees?
How might sympatric sirenian species (or paleospecies)
partition the available resources?
What effects do sirenians have on energy flow and community
structure of seagrass and other aquatic ecosystems?
Evolutionary:
What effects have sirenians had on evolution of seagrass
and other aquatic ecosystems?
Why have all sirenians except MydLgdamali2 apparently failed
to adapt to cool climates?
How are sirenians related genealogically to other mammals?
How much of sirenian biology reflects ELimitive mammalian
conditions? For example, what if anything does sirenian
sociality signify regarding evolution of sociality in
mammals?
Why did halitheriine dugongids die out?
Is bottom-feeding, as exemplified by DUgnqg, an
overspecialization and evolutionary dead end for sirenians?
We already have partial answers to some of these questions,
or maybe even complete answers that are not yet published. The
rate at which new knowledge of sirenians is being generated is
gratifying, but I still wonder whether we are in danger of
running out of good questions. Further suggestions are welcome at
any time! DPD
REQUEST
Dr. Rodney Salm (Dept. of Tourism, Ministry of Commerce &
Industry, P.O. Box 550, Muscat, Oman) asks: "Would any readers
know of references to dugongs in Oman? No matter how old!"
ABSTRACTS
Submerged Times gf Dusgngs (P.K. Anderson). Dugongs, like
cetaceans, are restricted to the water and carry out most of
their activities beneath the surface, but must surface to
breathe. The interval between appearances at the surface (down-
time) has been found to vary with locality, foraging mode and
forage species, activity, and reproductive status. An attempt was
made in 1983 to examine the relationship between down-time and
depth of water. Individual dugongs were followed and kept in view
by divers. Down-times recorded by this method were longer than
those recorded previously by surface methods. Data obtained in
water of varying depths suggest a trend for dugongs to remain
submerged longer in deeper water. Possible explanations of these
variations are discussed. [From IX International Reunion of the
Mexican Society for the Study of Marine Mammals, La Paz, Baja
Calif. Sur, March 29-31, 1984.]
E9g1gy And Behbarilr g Manateea (Trichechus manatus) in tbhe
EigiQn Q EmfiliangQ alpa a Tabaffg (L. del C. Colmenero Rolon,
E.E. Hoz Zavala, et al.). Other papers have indicated the
importance of the region of Emiliano Zapata in Tabasco state
[Mexico] as a place of aggregation of manatees. This can be
attributed to the influence of rivers and lagoons that have
physical and chemical conditions for supporting large numbers of
this mammal and a vegetation pattern favorable for them. The
observations made indicate that the manatees move from rivers to
the proximal lagoons according to the availability of food and
that these local movements are correlated also with seasonal
changes. The rainy season produces the increment of water level
of the rivers and permits the approach of the manatees to the
lagoons. They retreat later when the water level declines in the
dry season. It has also been observed that their reproductive
behavior is closely related to seasonal changes. The answers to
questions asked many local persons permit us to corroborate the
idea that the manatee population in this region is recovering,
thanks to the protection that this species receives. [From IX
International Reunion of the Mexican Society for the Study of
Marine Mammals, La Paz, Baja Calif. Sur, March 29-31, 1984.]
1zglQ2gY Distribution4 and Qnuaclatin ofL the Amazoflian
Manatee, Trichechus inunguis, in ZEcuadg (R.M. Timm and L. Albuja
V.). The Amazonian manatee, 2T inuguia, is one of the largest
mammals on the South American continent, but it remains poorly
known. The recorded distribution of Amazonian manatees includes
much of the central Amazon basin in Brazil, eastern Peru, and
extreme southeastern Colombia. We suspected that Amazonian
manatees might also occur in eastern Ecuador, and during the fall
of 1983 we searched for them in several river systems of the Rio
Napo drainage. We observed T, inuaguia at three separate
localities in Napo Province, Ecuador: on 1 October at Laguna
Grande de*Cuyabeno (00 00', 76 11'W, el. 210 m), on 28 October at
Laguna Zancudo Cocha (00 34'S, 75 29'W, el. 200 m), and on 2
November at Laguna Lagarto Cocha (00 29'S, 75 07'W, el. 200 m).
All observations were either early in the morning or at sundown.
Water temperatures at the surface ranged from 25.5 C to 32.5 C;
pH ranged from 5.5 to 6.0. These waters are considered blackwater
lagoons. At Laguna Grande de Cuyabeno the population of manatees
is small and essentially not harvested at present by the Siona
Indians. At Laguna Zancudo Cocha the population of manatees is
small and there is a limited harvest each year by the local
settlers and military. At present there is a good population of
manatees at Laguna Lagarto Cocha, but harvest from a single meat
hunter is extensive. Trichechus inuoguil is in need of complete
protection in Ecuador. [From 64th Annual Meeting of the American
Society of Mammalogists, Arcata, Calif., June 24-28, 1984.]
The following three abstracts are of papers presented to the
II Encontro Sobre Mamiferos AquAticos, XII Congresso Brasileiro
de Zoologia, Campinas, Brazil, Jan. 27-Feb. 1, 1985. They are
here translated from the Portuguese.
2igfatibility Q1 A&guiatic ants by the Amazonian Manatee
(Trichechus inunguis) (R.C. Best, J. Atkinson, R. Prince, and
G.R.S. Moreira). As part of a study on the biology and
conservation of the Amazonian manatee, we made tests of
digestibility using aquatic and semiaquatic plants from different
areas. These were: capim coldnia [pasture grass] (Dtachiiria
nutmia)r abgmba sp., and water lettuce (El~tia atratitesa).
Feces and urine of manatees (n=6) were collected on the last 4
days of a 15-day experimental period. Plant consumption varied
between 4% and 12% of the live weight of the animals. Using
lignin (which is indigestible) as an indicator, we calculated the
apparent digestibility (AD) of the dry material of the plants.
The results were: 58% for EaflaHbiia; 51.3% for Cabgha; and
53.4% for Eiatia. "TFse efficiencies are similar to those of
other large herbivores. The digestions of protein-N of the diets
were 58%, -9.1%, and 42.3%, respectively; the negative
digestibility of protein in the CabqMba diet is related to the
presence of tannins in this plant. The AD of cellulose was 63%,
Rnf .f and 73.8%, respectively, showing a high utilization -of
fiber in the monogastric digestive tract. The assimilation of
energy was 53.2%, 22.8%, and 26.4%, showing a greater utilization
of the grasses than of the aquatic plants. Analyses of Na+ in the
urine, given that the level of Na+ can be very low in the grass
diet (X/=20.5 mEq/l; max=31.9 mEq/1) or high as in the Cabomba
diet (X/-94.1 mEq/1; max-135 mEq/1), showed that the manatee can
excrete extremely dilute urine to avoid loss of salts. These
results are discussed in relation to the ecology and possible
captive breeding of this endangered species.
EraliminaLy Studiea on ths Digsatimc EgphybaIlol.agX Qf the
Aaazgnian Manatge (Trichechus inunguis) (J.A.A. Gomes and R.C.
Best). In order to obtain basic data indispensable to the
understanding of the ecology and digestive physiology of the
Amazonian manatee, we studied the voluntary consumption and rate
of passage of food through the digestive tract of TrZhchabua
inUnSuiS. We also examined the changes in these parameters using
four different diets and three kinds of solid plastic markers. In
this experiment we employed two males and two females with body
weights of from 78 to 175 kg. The percent daily consumption, in
relation to body weight, varied between 2.87% (diet B) and 3.81%
(diet A). We found a negative correlation between the percent
.consumption and body weight. The daily consumption varied
inversely with the fiber content of the diets. The different
markers differed significantly in retention time. The retention
time of food seems to vary directly with the fiber content of the
diet. Individual variations were found. We intend to continue
these studies in order to obtain more specific data on
digestibility in the manatee.
GLSS5 Antomy gf the Lidays Q Sotalia fluviatilis ICctaca
= Delpbinidasl and Trichechus inunguis 9Sirnnia = Trichechidal
(A.L.P. Miranda). Material was obtained from a male SQtalia
fluxiatilia and five Uigchbhua inunsuis. In S fluyatilia the
renal lobules were separated and sorted into 6 groups according
to their external appearance (apparently one lobule Group I;
two lobules apparently fused Group II; etc.). The numbers of
lobules in the right and left kidneys were 316 and 284,
respectively. After this sorting, the lobules were cut in a
sagittal plane, their dimensions were noted, and they were
separated into 3 new groups according to the number of papillae
lobulee with one papilla Group 1; with two papillae Group 2;
etc.). In the right kidney, the classification by external
appearance coincided with the classification by papilla count
with an accuracy of of 93.5% in Group I, 23.2% in Group II, and
2.3% in Group III. There was no agreement in the other groups.
The left kidney the agreement was 95.38% in Group I, 19.64% in
Group II, and 2.74% in Group III, again with no agreement in the
other groups. The mean weights of a lobule and papilla were 0.09
0.01 g and 0.060.01 g, while the maximum and minimum were 0.1 g
and 0.03 g, respectively. The kidneys of T, iaunguis were also
cut in a sagittal plane. No form of internal or external
lobulation was observed. In the 5 animals examined, the papillae
were counted, weights and measurements were taken, and the volume
was examined.
RECENT LITERATURE
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on fossil marine mammals. Mar. Mamm. Science 1(1): 15-53.
Buergelt, C.D. 1984. Observations on manatee mortality in
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Virginia. In: L.W. Ward and K. Krafft (eds.), Stratigraphy
and Paleontology of the Outcropping Tertiary Beds in the
Pamunkey River Region, Central Virginia Coastal Plain. 1984
Field Trip Guidebook, Atlantic Coastal Plain Geol. Assoc.:
224-225. 1 pl.
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and Pliocene of San Diego County, California. Trans. San
Diego Soc. Nat. Hist. 20(12): 169-188.
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288-293. [In Russian; English summary.]
Gann, T.W.F. 1911. Exploration carried on in British Honduras
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male reproductive organs of the dugong, QUSgng dug~a
(Sirenia: Dugongidae) with age and reproductive activity.
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CHANGES OF ADDRESS
Dr. Jane M. Packard, Dept. of Wildlife & Fisheries, Texas A&M
University, College Station, Texas 77843 USA
Dr. Galen B. Rathbun, U.S. Fish & Wildlife Service, P.O. Box 70,
San Simeon, Calif. 93452 USA
Dr. Rodney V. Salm, Leader, Coastal Zone Management Project,
Dept. of Tourism, Ministry of Commerce & Industry, P.O. Box
550, Muscat, OMAN
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