Transition Metal Accumulation in Caudal Scutes of American Crocodiles (Crocodylus acutus) from Belize

Abstract

Contamination of aquatic environments is a global concern that poses risks to wildlife and human health. Due to their high trophic status, broad diet, long life span, and occurrence in a variety of aquatic habitats, crocodilians are susceptible to exposure and accumulation of numerous persistent environmental contaminants, including metals. Exposure to these metals may have potential health hazards and have a more pronounced effect on populations already subject to other stressors (e.g., habitat loss, deliberate killing). Previous studies have documented transition metals in caudal (tail) scutes of crocodiles from remote areas of mainland Belize; however, no such data are available for crocodiles living on the country’s offshore islands (cays). In this study, we examined transition metal concentrations in caudal scutes from American crocodiles (Crocodylus acutus) sampled from various localities on Ambergris Cay, Belize. In addition, a smaller number of C. acutus scutes from Costa Rica were also examined for comparative purposes. Sixteen metals were detected in scutes: Pb, As, Cu, Ag, Be, Cd, Al, Cr, Ni, Co, Mo, Sb, Se, Tl, Sn, and Zn, with Al, Zn, Cu, and Sn exhibiting the highest concentrations. Metal concentrations differed by sex, body size, site, and proximity to putative contaminant sources. Juvenile crocodiles generally contained the highest metal concentrations, and for many metals concentrations decreased with increasing body size.