SREL Reprint #2354

Environmental contaminants as concerns for the conservation biology of crocodilians

I. Lehr Brisbin, Jr., Charles H. Jagoe, Karen F. Gaines, and Joan C. Gariboldi

Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, South Carolina 29802, USA

Abstract: Historically, concerns for the fate and effects of environmental contaminants have not been a high priority for those concerned with the conservation biology of crocodilians. However studies of other groups of vertebrates suggest that this is probably a mistake. With advancing understanding of factors impacting crocodilian populations, it is becoming increasingly obvious that contaminants can have significant impacts upon a number of these species. There are three classes of environmental contaminants: radionuclides, heavy metals and organics, including the estrogen inhibitors Radionuclides are generally the least important in terms of their overall impact upon global crocodilian populations. They are of concern only in certain localized areas such as those surrounding nuclear industrial facilities. Heavy metal contamination however occurs worldwide, and is of concern to many tropical populations of caimans and crocodiles inhabiting wetlands contaminated with mining effluents, particularly those associated with the extraction of gold and copper. Mercury contamination of alligator populations in the southeastern United States is widespread and may, under some conditions, limit the advisable consumption of alligator meat by humans in this area. Concern for the global impacts of anthropogenic estrogen inhibitors is of great interest in environmental toxicology today, and studies of the impacts of these contaminants upon the reproduction of American alligators (Alligator mississippiensis) were among the first to document the harm caused by these chemicals upon free-living wildlife.
This paper summarizes studies concerning the fate and effects of environmental contaminants upon crocodilians. This survey indicates a general lack of information regarding the importance of observed levels of contaminants in both individual animals and populations. Such information is essential for predicting how contaminants may be limiting population reproduction or viability, particularly in concert with habitat destruction, over-harvest and other limiting factors. This survey also reveals the importance of having a thorough understanding of the basic ecology, behavior and natural history of the animals involved, with this being particularly important for predicting the role that meat from some crocodilians could play as a potential vector of environmental contamination to the human food chain.

SREL Reprint #2354

Brisbin, I.L., Jr., C.H. Jagoe, K.F. Gaines, and J.C. Gariboldi. 1998. Environmental contaminants as concerns for the conservation biology of crocodilians. pp. 155-173 In: Proceedings of the 14th Working meeting of the Crocodile Specialist Group of the SSC of the IUNC - The World Conservation Union, Gland, Switzerland.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).