() Ecotoxicology of crocodiles living in contaminated aquatic environments in Central America.
Rainwater, T1, Wu, T2, Finger, A1, Canas, J1, Yu, L1, Reynolds, K1, Combiatore, G1, Platt, S3, Cobb, G1, McMurry, S1, 1 Texas Tech University, Lubbock, Texas, USA2 University of Alaska Fairbanks, Fairbanks, AK, USA3 Oglala Lakota College, Kyle, SD, USA
ABSTRACT- Regulations governing the production, distribution, and use of chemicals in developing countries are often scant or inadequately enforced. As a result, large quantities of chemicals are routinely used in the tropics for agriculture, mining, crop storage and vector control at rates often comparable to or higher than those in developed countries. In addition, many compounds banned in most industrialized countries (e.g., DDT) are still commonly used in tropical areas. However, despite the wide use and occurrence of these chemicals in developing countries and the high biodiversity of the tropics, few studies have examined the exposure and response of tropical wildlife to environmental contaminants. Here, we report results of ongoing studies to assess exposure and response of Morelet's (Crocodylus moreletii) and American (C. acutus) crocodiles to environmental contaminants in Belize and Costa Rica. In Belize, multiple organochlorine (OC) pesticides have been detected in crocodiles and their eggs from both freshwater and marine habitats as well as in sediments, nest material, and multiple crocodile prey species from freshwater lagoons and rivers. In addition, mercury has been detected in 100% of crocodile eggs and tail scutes examined for this metal. In Costa Rica, multiple OCs and metals have been detected in American crocodile tail scutes, with DDT, DDE, endrin, methoxychlor, mercury, and zinc occurring in 100% of samples analyzed. Steroid hormone concentrations, male phallus size, and plasma vitellogenin concentrations have been examined as endpoints of contaminant-induced endocrine disruption in Morelet's crocodile in Belize, but an inability to locate non-contaminated reference sites for comparative purposes makes results of these analyses difficult to interpret. Based on these results, we identify data gaps and provide recommendations for future ecotoxicological studies on Central American crocodilians.
Key words: crocodiles, metals, tropical ecotoxicology, organochlorine pesticides