TP9 Ecotoxicology of Reptiles
Tuesday, 15 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(GRO-1117-727604) Thyroid function in hatchling American Alligators from contaminated sites in central Florida.

Wiebe, J^{1, 2}, Scarborough, J², Rauschenberger, R³, Smith, J¹, Gross, T^{1, 2}, ¹ USGS-FISC-CARS, Gainesville, FL, USA² University of Florida, Gainesville, FL, USA³ USFWS, Jacksonville, FL, USA

ABSTRACT- Several studies have demonstrated reproductive impairment for alligators exposed to a complex mixture of oprganochlorine pesticide residues (OC's). In addition to maternal mediated effects on egg quality and egg viability/hatchability, results have also documentd decreased offspring survivability and growth anomalies. Preliminary histological and hormonal evaluations of hatchling alligator thyroid activity suggest a potential relationship between organochlorine pesticide exposure and subsequent alterations in growth regulating tissues (i.e., thyroid). In order to evaluate this relationship further, clutches (n=10/site) were collected from lakes Apopka (High OC), Griffin (Intermediate OC), Orange (Control) and Emerelda Marsh (High OC). Hatchlings (n=15) were captive raised for a period of eight months. Morphometric measurements as well as monthly blood samples were collected. Plasma was utilized to monitor circulating free and total thyroxine (T4) concentrations (growth indicating hormones in reptilian models). In addition, thyroids were harvested from a subset (n=3 hatchlings / clutch) on a quarterly schedule in order to examine the potential relationship between growth morphometrics and subsequent alterations in thyroid function. Thyroid activity was quantitatively assessed utilizing morphometric analyses examining follicular diameter, area, epithelial height and colloid content. These data indicate altered thryoid function, and growth for alligator hatchlings in response to maternal and embryonic exposures to OC's.

Key words: Thyroid, Organochlorine Pesticides, Growth, Alligator