MA3 Aquatic Ecotoxicology
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() Reproductive effects of organochlorine pesticide exposure in a captive population of American alligators (Alligator mississippiensis).

Rauschenberger, R1, 2, Wiebe, J1, 2, Buckland, J1, 2, Smith, J1, 2, Sepúlveda, M1, Gross, T1, 2, 1 University of Florida, Gainesville, Florida, USA2 United States Geological Survey - Florida Integrated Science Centers, Gainesville, Florida, USA

ABSTRACT- American alligators (Alligator mississippiensis) inhabiting organochlorine pesticide (OCP) contaminated sites in Florida produce eggs with high OCP concentrations and poor hatch rates in comparison to those of reference sites. Reduced hatch rates in OCP contaminated sites are primarily due to early and late stage embryo mortality. The objective of the present study was to use captive adult alligators to test the hypotheses that maternal exposure to an environmentally relevant OCP mixture results in increased OCP concentrations in eggs, reduced hatch rates, and increased rates of embryonic mortality. A total of 27 adult alligators (13 males and 14 females) originating from a zoological facility were distributed among 13 semi-natural enclosures (1:1 sex ratio). Males and females in 7 pens were chronically dosed with a mixture of p,p'-DDE, toxaphene, dieldrin, and chlordane which they received in a standardized diet. Treated females produced eggs having higher OCP concentrations and reduced hatch rates as compared to controls. During the same two year period, OCP burdens (mean ± standard error) in eggs of captive treated females (11,855 70 ± 2,757 ng/g) were similar to those of wild females from OCP contaminated habitats (10,196 ± 1,781 ng/g), and OCP burdens in eggs of captive control females (31 ± 4 ng/g) were less than those of wild females (102 ± 15 ng/g) from reference sites. Furthermore, the differences in hatch rates between the captive treated (8 ± 8%) and control populations (41 ± 14%) were similar to the differences between hatch rates of wild populations from OCP contaminated sites (41 ± 5%) and reference sites (65 ± 5%). Although the hatch rates of the captive control group were less than those of reference sites, they were within expected ranges for a typical captive alligator population. This novel captive dosing experiment indicates that the high OCP egg burdens and poor hatch rates documented in wild alligator populations inhabiting OCP contaminated sites can be reproduced in a captive population via parental OCP exposure, suggesting that parental OCP exposure may adversely affect egg hatchability. This study is also the first we know of that has induced endogenous embryonic OCP exposure in a crocodilian model. Continuation of this on-going study will aid in gaining better understanding of the effects of OCPs on crocodilian reproduction.

Key words: reproduction, reptile, organochlorine, egg

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