Few studies have assessed contaminants and their potential adverse effects on wildlife in the south Florida ecosystems. Available data indicates a wide array of organic contaminants, including pesticides, PCB's and PAH's, as well as mercury and nutrients (phosphorous) are present and of primary concern in south Florida (Kolipinski and Higer, 1969; Waller, 1982; Haag and McPherson, 1997; Miles and Pfeuffer, 1997). The potential adverse effects on wildlife are not known, although a wide variety of fish, reptiles, invertebrates, amphibians, birds and mammals utilize this critical ecosystem. Recent results have linked previous water management efforts to altered contaminant distributions and potential wildlife exposures. The South Florida Restoration Task Force has initiated a hydrologic restoration as a primary goal of ecosystem restoration and resource management. These efforts are designed to restore original habitat conditions to support viable wildlife populations while providing available water resources. However, these restoration efforts have not considered nor evaluated the potential adverse effects on contaminant distributions and subsequent wildlife exposures. The project assesses current wildlife contaminant exposures and predicts and monitors future restoration-driven exposures. Results can be used to prevent adverse effects on wildlife within the south Florida ecosystems.

To determine whether chemical stressors/contaminants in south Florida harm wildlife, it is important to study animals that are potentially exposed and appear sensitive to contaminants. Utilization of several receptors/species at multiple trophic levels have been utilized for the current study to detect potential exposures and adverse effects within the south Florida ecosystems. The American alligator (Alligator mississippiensis), largemouth bass (Micropterus salmoides), and brown-bullhead catfish have been utilized as receptors for study. These species are important in south Florida ecosystems and of high priority due to our extensive previous data which indicates their utility as bioindicators of chemical stressor/ contaminant effects in other Florida ecosystems.

Also, species from two other taxonomic groups and trophic levels were selected for study: freshwater mollusks and wading birds. Wading bird populations have been the subject of frequent monitoring efforts for the south Florida ecosystems. White ibises (Eudocimus albus) and great egrets (Casmerodius albus) are being utilized for the current assessment of potential contaminant exposures and effects in south Florida. White ibises have shown the greatest declines in reproductive success and population size, and are also of special interest in the Everglades. The white ibis is a key species because it remains the most numerous breeding wading bird in the Everglades, and restoration of breeding populations of ibises would have a huge numerical effect on the total population of breeding birds in the ecosystem.

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. Indeed, invertebrates are an important, trophic level within ecosystems and a group with high exposure potentials to a wide variety of environmental contaminants/chemicals. Fresh-water mollusks, mussels (Elliptio buckleyi and Utterbackia imbecillis) and the Florida apple snail (Pomacea paludosa), are being used as models for general toxicity and as important environmental sentinels, early signals, of environmental effects for contaminants such as endocrine-disruptors.

Efforts have involved the collection of alligators at six 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 south Florida. These analyses indicated a severe decline in freshwater mussels populations in coastal areas, Miami-Dade County, Water Conservations Areas, and canals within the Everglades. Most importantly, these analyses suggested that altered population status may be partly due to altered reproductive function and potential contaminant causation. Additional assessments of fish throughout the south Florida ecosystems is currently underway. Additional assessments of wading birds and other species will be conducted in Spring 2001 and preliminary risk assessments will be completed.

A complete ecological risk assessment requires hazard identification, documentation of adverse effects, demonstration of exposure, and knowledge of dose-response relationships. Currently available information concerning potential contaminant effects for wildlife within south Florida consists primarily of the identification of exposure to potential hazards. Indeed the south Florida ecosystem is contaminated with a wide array of chemical stressors/contaminants, including chlorinated hydrocarbon pesticides, heavy metals, water soluble pesticides, and nutrients. However, evidence of adverse effects, cause and effect relationships, or dose-response relationships have 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.

The initial exposure assessment is utilizing sampling regimes at selected critical areas to provide an evaluation of soil, water and sediments. These evaluations include pH, percent water, grain size, cation exchange capacity, and total volatile solids as well as quantitation of organochlorine pesticides and polychlorinated biphenyls (PCB's, polynuclear aromatic hydrocarbons (PAHs), organophosphate pesticides (Ops), nitrogen based herbicides, phenoxy-acid herbicides, and heavy metals. Tissue samples from the ecological receptors , outlined above will be analyzed for lipid content, as well as quantitation of organochlorine pesticides and polychlorinated biphenyls (PCB's, polynuclear aromatic hydrocarbons (PAHs), organophosphate pesticides (Ops), nitrogen based herbicides, phenoxy-acid herbicides, and heavy metals.

These studies are expected to show 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 may show a decrease in sensitive species in sites with significant contaminant of exposure. Study results are expected to demonstrate convincing evidence as to the causal role of specific chemicals and/or mixtures. Finally, studies comparing responses of these selected species will likely provide major insights into the basis of interspecies differences in sensitivity to contaminants.

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(This abstract was taken from the Greater Everglades Ecosystem Restoration (GEER) Open File Report (PDF, 8.7 MB))

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