PW09 Pesticide I
8:00 AM - Wednesday
(PW144) Necropsy findings in American alligator hatchlings from organochlorine contaminated lakes in Florida.
Sepulveda, Maria1, Del Piero, Fabio2, Rauschenberger, Richard1, Buckland, Janet1, Wiebe, Jon3, Gross, Timothy3, 1 University of Florida, Center for Environmental & Human Toxicology, Gainesville, FL, USA2 University of Pennsylvania, Department of Pathobiology, Kennett Square, PA, USA3 USGS Center for Aquatic Resource Studies, Gainesville, FL, USA
ABSTRACT- Increased American alligator (Alligator mississippiensis) embryo and neonatal mortality has been reported from several north-central Florida lakes contaminated with old-use organochlorine pesticides (OCPs). To date however, a clear relationship among these contaminants and egg viability has not been established, suggesting the involvement of additional factors in these mortalities. Thus the objective of this study was to conduct a detailed pathological examination to determine the ultimate cause of mortality of alligator hatchlings, and to better evaluate the role of OCPs in these mortalities. Between 2000 and 2001, a total of 236 dead alligators were necropsied at or near hatching (after approx. 65 days of artificial incubation). Dead hatchlings were collected from a total of 18 clutches ranging in viability from 0 to 94%. Total OCP concentrations in yolk ranged from approx. 100 to 19,000 ppb, wet weight. The most common macroscopic findings were the presence of generalized edema and organ congestion (33% each), followed by severe emaciation (15%) and gross deformities (3%). Histopathological examinations revealed the presence of lesions in close to 10% of the animals, with over half of the cases being pneumonia, septicemia, and nephritis of bacterial origin. Within and across clutches, dead hatchlings were significantly smaller and lighter compared to their live-counterparts. None of these abnormalities were observed in hatchlings from the reference site. Overall these results indicate that general growth retardation was a major contributing factor in the observed mortalities. Alterations in growth and development could only be partially explained by OCP contamination, and thus it is likely that additional factors are involved. In this respect, our laboratory is currently examining the relationship among survival of early-life stages of alligators and several egg nutritional components.
Key words: mortality, pesticides, alligators, growth