PARENT SESSION

2N - Field Studies
Poster Hall
8:30 AM - Monday, 28 April 2003
Chair: Liess, M.¹, ¹
Co-chair: Berghahn, R.², ²

(MOP/133) Incidence of Embryonic Mortality in the American Alligator and the Relationship to Organochlorine Pesticide Exposure: Paired Field and Laboratory Evaluations.

Gross, Timothy^{1, 2}, Sepulveda, Maria², Wiebe, Jon¹, Buckland, Janet², Rauschenberger, Richard², Monck, Eileen¹, ¹ USGS-FISC, Gainesville, FL, US² University of Florida, Gainesville, FL, US

ABSTRACT- Our laboratory has been evaluating the relationship between maternal and egg exposures to organo-chlorinated- pesticides (OCPs) and subsequent reductions in egg and embryo quality in the American Alligator. Results have demonstrated a strong correlation between OCP exposure and an increase in the incidence of developemntal mortality, however, cause-and-effect relationships to specific OCPs is unclear. The current study examined the relationship between maternal expsoures to OCPs and a subsequent reduction in the quality of eggs/embryos for alligators exposed under natural and laboratory conditions. Efforts with natural/field exposures involved a 4 year survey of the incidence, stage of developmental moratlity and OCP exposure for alliagtors across several sites with low to high OCP burdens in Central Florida. Approximately 20 clutches of eggs were collected yearly from each of 4 sites as well as 5-10 adult females associated with specific nests at each site. Laboratory exposures/treatments utilized a captive population of 26 alligators (1:1 sex ratio), maintained in breeding pairs. Captive animals were exposed to OCPs via dietary intake to simulate both low and high OCP exposures (mixture of DDE, chlordane , dieldrin and toxaphene). Clutch analyses included fecundity, vaibility/hatchability, developmental mortality and yolk OCPs. Developmental mortality was evalauted as unbanded eggs (pre-ovipositional mortality/unfertilized), early (<30 days of devlopment), late (>30 days) and post-hatch. Field results demonstrate similar OCP exposures within sites and a strong correlation between maternal and egg burdens. Nonetheless, approximately 55% of all clutches within each site have low embryo mortality and hatch rates similar to eggs from low OCP sites. OCP exposed sites result in a significant increase in the number of clutches with high developmental mortality and a differential pattern of mortality for each site. Preliminary results for the laboratory exposures indicate a large increase in develomental mortality for high OCP exposures (mixture of OCPs)similar to naturally exposed alliagtors. These results continue to suggest that the developmental effects of OCPs in alligators are mediated through maternal exposure and subsequent effects on egg and embryo quality. (Funded by NIEHS-SFBRP)

Key words: pesticides, alligators, developmental mortality, egg quality