PARENT SESSION
PS6 - Contaminant Effects on Amphibians & Reptiles
Sunday, 17 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P089) Effects of dietary methylmercury in juvenile corn snakes (Elaphe guttata).

Bazar, Matthew^*,1, Holtzman, David¹, Adair, Blakely³, Gresens, Susan¹, ¹ Towson University, Department of Biological Sciences, Towson, MD, USA³ Texas Tech University, The Institute of Environmental Health and Department of Environmental Toxicology, Lubbock, TX

ABSTRACT- We examined the behavioral and physiological response of corn snakes (Elaphe guttata) exposed to dietary methylmercury at five different dose concentrations during a 20-week period. Individuals were randomly assigned to five dose groups (control, n=10; 1.0 mg/kg, n=6; 2.5 mg/kg, n=6; 6.0 mg/kg, n=6; 12.0 mg/kg, n=6). Dose was calculated as mg methylmercury per kg snake. Snakes were fed with dead mice injected with either carbon filtered water (controls) or methylmercury chloride solution. Body mass and snout-vent length were recorded weekly and every four weeks, respectively, to examine growth rate. Scat and shed skins were collected and composited by dose group for mercury analysis. After 12 spiked meals, individual snakes were put through a behavioral assay that evaluated spatial learning ability. The task objective was to find an open hole in a brightly lit arena. Time and distance to the goal hole were measured over the course of 4 trials a day for 4 days. After 15 spiked meals the snakes were put through the behavioral assay again to evaluate memory. Snakes were then euthanized and tissues (i.e., brain, liver, kidney) were collected for histopathology, and a portion of the liver and blood were collected for mercury analysis. Snakes from all groups except the 12 mg/kg dose, showed an ability to learn the task. Survival in the 12 mg/kg group was zero percent. Preliminary results indicate that motor effects and reduced growth rate may occur before spatial learning ability is affected at the concentrations and exposure duration evaluated.

Key words: reptiles, methylmercury, behavior, growth