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

(GRO-1117-729313) An Evaluation of Organochlorine Pesticide Egg Treatment Methodologies in the American Alligator (Alligator mississippiensis).

Scarborough, J^{1, 2}, Wiebe, J¹, Rauschenberger, R², Sepulveda, M², Gross, T^{1, 2}, ¹ USGS-FISC-CARS, Gainesville, FL, USA² University of Florida, Gainesville, FL, USA

ABSTRACT- The ability to establish a relationship between organochlorine pesticide (OC) exposure and subsequent reductions in egg and embryo qualities in repiltes are complicated by a variety of environmental and physiological parameters. In order to examine this potential relationship in more detail, egg injection and topical treatment methodologies were evaluated in our laboratory for the American alligator. Method 1: Eggs (n=56 eggs/treatment) were injected at the pole with a mixture of DDE, dieldrin, toxaphene, and chlordane in 10uL of triolien (vehicle) at three concentrations (high, intermediate and low). Three controls were utilized to validate the injection technique (control, sham control and vehicle control). Mortality rates among all injected eggs (approx. 70%) appear to be a result of injection technique as opposed to OC exposure. Method 2: Eggs (n=30 eggs/treatment) were topically administered with alternating single and multiple OC mixtures of DDE, dieldrin, toxaphene, and chlordane in sixteen treatment groups to examine the relationship between single and multiple OC exposure and subsequent increases in embryonic mortality. Though embryonic mortality was low (approx. 20% / treatment), OC absorption into the egg as determined by GC-MS was extremely poor (less than a 2-4% transfer). Topical application of OC on reptilian eggs has been discussed in several studies and porposed as a viable technique or screen for endocine disruptors, however, our data indicate that injection techniques in alliagtiors are not a viable method of exposure and that topical exposures do not result in significant exposure. These resulkts as well as our previous efforts with turtles do not support the use of either model as a method for screening endocine dsiruptors and/or effects. Most importantly, these efforts strongly indicate that egg exposures are not a likley or significant route of exposure to OC's in wild reptile populations.

Key words: Alligator, Egg Injection, Topical Application, Organochlorine Pesticides