Project: Ecological Risk Assessment of Toxic Substances in the South Florida Ecosystem: Wildlife Effects and Exposure Assessment

Web Sites: Ecological Risk Assessment of Toxic Substances in the South Florida Ecosystem: Wildlife Effects and Exposure Assessment

Location: South Florida: Miami-Dade County, ENP, WCA's, Loxhahatchee, Big Cypress

Principal Investigator: Timothy S. Gross, tim_s_gross@usgs.gov, 352-378-8181 Ext 323

Project Personnel: Jon Wiebe, Carla Wieser, D. Shane Ruessler, Nicola Kernaghan, Marisol Sepulveda, 352-378-8181

Other Supporting Organizations: University of Florida, Florida Fish and Wildlife Conservation Commission

Associated Projects: Evaluation of infertile alligator eggs and contaminant effects in the South Florida ecosystem (T.S. Gross and K. Rice)

Overview & Status: This project will assess both current wildlife contaminant exposures, as well as predict and monitor future restoration-driven exposures. These efforts will enable an assessment, detection and potential prevention of adverse effects on wildlife within the South Florida ecosystems. Efforts during FY2000 have involved the collection of alligators at 6 sites throughout the South Florida/Everglades ecosystem. Contaminant analyses and preliminary assessments of potential effects are currently underway. These efforts have also included a full survey/assessment of freshwater mussels in historic locations throughout S. Florida. These efforts have indicated a severe decline in freshwater mussels populations in coastal areas, Miami-Dade County, WCA's and canals within the Everglades. Most importantly, these preliminary analyses have suggested altered population status may be partly due to altered reproductive function and potential contaminant causation. Complete analyses for invertebrates will be completed during Fall 2000. Additional survey/assessments of fish throughout the South Florida ecosystems is currently underway and will occur throughout Fall 2000. Additional assessments of wading birds are proposed for Spring 2000, as well as additional assessments of other species and the completion of preliminary risk assessments.

Needs & Products: To assess whether chemical stressors/contaminants in South Florida harm wildlife, it is important to study animals that are potentially exposed and appear sensitive to contaminants. Little is known about the effects of environmental contaminants on invertebrates, however, invertebrate species have been recognized as important environmental sentinels and serve as models for a wide variety of toxicity tests that utilize mortality and lethality as the endpoints of significance. A complete ecological risk assessment requires hazard identification, documentation of adverse effects, demonstration of exposure, and knowledge of dose-response relationships. Evidence of adverse effects, cause and effect relationships, or dose-response relationships has not yet been documented for specific contaminants or mixtures. It is critical that potential exposures and subsequent adverse effects be assessed for wildlife in South Florida to enable a complete ecological risk assessment as well as an assessment and evaluation of proposed restoration strategies. Results from these studies are expected to provide evidence of significant wildlife exposures to chemical stressors/contaminants in South Florida and adverse effects as a result of these exposures. Effects characterization will focus on non-lethal effects such as decreased health status, altered reproductive success, and endocrine disruption. In addition, it is likely that we will be able to demonstrate population and community level effects, primarily decreases, for sensitive species in sites with significant hazard of exposure. From the complementary findings of field studies and experimental exposures, we expect to be able to demonstrate convincing evidence as to the causal role of specific chemicals and/or mixtures. Finally, we expect that studies comparing responses of these selected species will provide major insights into the basis of the interspecies differences in sensitivity to contaminants.

Application to Everglades Restoration: The results of this study will greatly improve assessment of risk for selected wildlife species and for South Florida ecosystems. Overall, the proposed project will assess both current contaminant exposures as well as predict and monitor future restoration-driven exposures, to enable assessment, detection and prevention of adverse effects on wildlife in south Florida.