Found this on the Florida Alligators.
http://myfwc.com/gators/research/Rep...l%20report.pdf
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April 24, 2000
CONTACT: Dwayne Carbonneau (352) 955-2230
LAKE GRIFFIN ALLIGATOR UPDATE
In the past several days the Florida Fish and Wildlife Conservation Commission (FWC) has received several calls from residents of Lake Griffin reporting sick or dead alligators on or near their property, and asking that they be removed.
Since late1997, substantial numbers of large alligators have been dying of unknown causes on the lake located in Lake County near Leesburg. The number of dead alligators has been steadily increasing each year, with the peak die-off typically occurring in April and May.
While many of the affected alligators die in remote areas of the lake and are never seen by residents, others sometimes end up on the shorelines near homes located on the lake. When this occurs, residents who would like the dead alligators removed are asked to call the FWC at 1-800-342-9620 or 352-732-1225 and make arrangements to have them taken away. The toll-free number is normally used only for wildlife emergencies and violations, but for now calls to request the removal of sick and dead alligators on Lake Griffin only, will also be accepted on this line. All other informational calls should be directed to 352-732-1225.
Every two weeks, FWC biologists survey Lake Griffin to count the number of dead alligators and have recorded 244 since November, 1997. From January through March of this year, 68 dead alligators have been found which is more than twice the number found during the same period last year, and more than was found during all of 1998.
To help discover what is causing the deaths, a team of scientists from the University of Florida, the Florida Museum of Natural History, the U.S. Geological Survey, the St. Johns River Water Management District, the U.S. Fish and Wildlife Service and the FWC are cooperating in a joint investigation of the die-off.
Sick alligators have been captured and examined by wildlife veterinarians and experts from the University of Florida. The alligators are lethargic and uncoordinated, but otherwise in good physical condition. Tests have shown no consistent bacterial or viral diseases associated with the disorder, however, most of the alligators have a nervous system disease that includes a brain lesion, which experts believe is probably the cause of death.
The question remains, however, what is causing the brain lesions. Clinical tests and the type of lesions suggest that some sort of toxin is responsible. However, toxic metals that can cause such disorders, including mercury and lead, are insignificant in the Lake Griffin alligators which have been tested.
Preliminary checks for pesticides also indicate relatively low concentrations, but further tests are needed.
The problem may also stem from nutritional deficiencies. Changes in fish and other prey populations due to changes in the water quality may have affected the nutritional value of the alligators' food sources.
Currently, alligator tissues are being examined for a wide range of pesticides and several tests for nutritional disease will be performed over the next few months.
Blue-green algal blooms are also a possible source of toxins that could cause nervous system disorders. Alligator tissues are being examined for algal toxins, but little is known about the identification and toxicology of algal toxins, particularly for Cylindrospermopsis raciborskii, a relatively new blue-green algae that has become dominant in Lake Griffin since the mid-1990s. Investigations of the toxic effects of Cylindrospermopsis on alligators are being initiated.
The FWC will continue alligator surveys on Lake Griffin until the problem is resolved, and will continue to collect sick alligators to further document the disorder.
http://www.floridaconservation.org/f.../nrc-gall.html