Ecotoxicology of crocodilians
All species of crocodilians are long-lived, top-level carnivores that are integral components of aquatic, wetland, and marine/estuarine ecosystems. However, they are often excluded from studies on environmental contamination and ecological risk assessments. Available organic (including endocrine disrupters), inorganic, and radionuclide contaminant accumulation and effects studies for crocodilians were reviewed and summarized to facilitate the use of existing data, reveal the primary information gaps, promote the inclusion of crocodilians in environmental contamination studies and ecological risk assessments, encourage further ecotoxicological studies, and assist in the development of future research priorities. Environmental contamination studies were not available for more than half of the world's 23 crocodilian species. The majority of information available (almost 70% of reviewed studies) concerning environmental contaminants and their accumulation and effects on crocodilians was for the American alligator (Alligator mississippiensis) as a result of the considerable research effort on the effects of endocrine-disrupting contaminants (EDCs) on the alligator population inhabiting Lake Apopka, Florida and the many studies concerning mercury contamination in the southeastern United States, considered to be the most serious environmental threat to that area. With the exception of the extensive research on the effects of EDCs on Lake Apopka's alligators, research on the effects of environmental contaminants on crocodilians is lacking. The review indicated that the effects of EDCs on crocodilians are not confined to Lake Apopka and may occur in crocodilians in many parts of the world, especially in developing tropical areas where organochlorine pesticides are used extensively. For inorganic contaminants, determining the effects of mercury on crocodilians should be the highest research priority.