The problem. An unknown factor or factors appears to be affecting alligators and other wildlife in Lake Griffin. Between 1994 and 1997 the hatch rate of alligator (Alligator mississippiensis) eggs collected on Lake Griffin and hatched in commercial facilities dropped from a range of 40%-60% to less than 10%. Since the summer of 1997 observations of dead adult alligators in Lake Griffin have increased to 2-4/week. In other lakes in Florida ‘normal’ alligator egg hatch rates fall in the range of 75%-90% and it is rare to see dead alligators at all. Studies of sportfish in Lake Griffin (Black bass, Micropterus salmoides, and Speckled perch, Pomoxis nigromaculatus) indicate missing year classes and reduced reproduction in these species are causing a virtual collapse of the formerly lucrative sport fishery. Whether other organisms in the system such as waterbirds, turtles, fish or invertebrates are affected is not yet known.

Over the same period (mid 1980’s to present) Lake Griffin has undergone some profound changes in ecology similar to those observed in many highly eutrophic Florida lakes. The lake has changed from a clear-water, sand bottom lake dominated by rooted aquatic macrophytes and supporting extensive sportfish populations to a turbid water system characterized by extensive flocculant organic sediments, dominated by unicellular algal blooms and planktoniverous fish (Gizzard shad, Dorosoma cepedianum). Increased loading of sediments, nutrients and contaminants from human activity in the surrounding watershed is thought to be driving these changes. Occasional die-offs of fish (shad and Gar) and freshwater turtles have been noted but not adequately quantified to evaluate.

These observations have heightened concerns about the effects of intense agricultural activity and urbanization on adjacent wetland ecosystems. To address these concerns, we propose the coordination of multi-disciplinary research conducted by State, Federal and University researchers on a series of central Florida lakes. Recent preliminary communications among these agencies (listed below), has revealed additional ecosystem changes including, water quality (N, PO4, turbidity, chlorophyll), vegetation changes, and endocrinological disruption in alligators, fish and turtles. Blooms of phytotoxic blue-green algae which are implicated in wildlife mortality in other areas have also been observed.

The lakes of central Florida are highly manipulated environments subject to multiple anthropogenic inputs such as fertilizer and pesticide run-off, sewage treatment effluent, aquatic plant and insect control, and water level manipulation. "Muck farming" on these lakes involved diking of previous sawgrass marshes, intense pesticide use, and repetitive draining and flooding, transporting contaminants and nutrients into the lakes. The causal linkage among these events and observed wildlife effects is not yet clear, but probably involves ecological interactions requiring a multi disciplinary approach. Endocrine disruption by contaminants was implicated in the reproductive failure in alligators and turtles in Lake Apopka in the 1980's. Available data from nearby Lake Griffin suggest additional or alternative causes such as phytotoxic blue-green algae and interactions of eutrophication, food web changes, wildlife nutrition, stress and disease which also require examination.

A major new factor in the ecosystem function of Lake Griffin and several similar lakes in Central Florida is the establishment of Marshland restoration systems on former muck farms. The farm lands supporting these projects are known to have been subject to large loads of fertilizer, pesticide and herbicides. During their agricultural operation these areas were repeatedly flooded and then pumped dry to control nematodes and other pests, transferring biogenic compounds to the lake waters and sediments. The State of Florida has acquired these agricultural lands adjacent to the lakes and is returning them to natural marsh systems. Flow of lake waters through these restored marshes is designed to capture sediment and nutrient (Phosphorus and nitrogen), removing it from the Lake and reversing recent hyper-eutrophication of these systems. It is not yet clear to what extent contaminants which have already entered the lakes and are present in the biological components and the sediments, will be removed by this process, and to what extent marsh throughflow systems transfer contaminants to the lake. While the long term goal is obviously an overall improvement in the ecosystem function, and a restoration of wildlife and sport fish populations, it seems possible that transient and unstable intermediate states may occur which may have negative effects on wildlife populations. The challenge for this project is to identify sources sinks and pathways of contaminants, establish links (if any) between contaminants, eutrophication and effects on wildlife populations and to propose methods of operation of restoration techniques which will minimize these negative effects to ensure the long term beneficial results of restoration.

We believe that this general problem, eutrophication and contaminant effects in lakes of the Southeast, is of wide interest in the region. The concept of creating a formal cooperative venture between agencies and institutional researchers, and potentially extending to local government and public entities, may provide a model for addressing these complex problems on a regional basis and provide useful guidelines for integration of research and management efforts on a national basis.

Several cooperating agencies have existing research and monitoring programs addressing different aspects of the issue independently. These separate, relatively small projects could be enhanced by coordinating their efforts. This core of activity will be the foundation for a much larger, directed program involving funding from additional granting sources such as EPA, USDA, NIEHS, US FWS, and private sources. This coordination has been initiated with pilot funding from the Florida Game and Fresh Water Fish Commission to hire a coordinator. This proposal is to develop proposals, coordinate proposal development, integrate research activities, and promote dissemination research results. Advantages of this integrated approach are: to avoid duplication of effort, to efficiently distribute biological samples for multiple use, to share allocation of resources and logistic support, to synergise collection and analyses of data, to coordinate management of information to the press and to the public. To support these activities an intranet will be developed to communicate among researchers and the NBII.

Participating Agencies:

• FL Cooperative Fish and Wildlife Research Unit
• FL Museum of Natural History
• FL Game and Fresh Water Fish Commission
• St. John’s River Water Management District
• US Geological Survey, Biol. Resources Div., Florida Caribbean Science Center
• FL Department of Environmental Protection
• University of Florida (Departments of Zoology, Wildlife Ecology and Conservation, Fisheries and Aquatic Sciences, College of Veterinary Medicine)