Assessment of Maternal Contaminant Burden by Analysis of Snapping Turtle Eggs

Snapping turtles ( Chelydra serpentina serpentina) have been extensively used as an ecosystem and localized indicator of tissue contaminant bioaccumulation, and for monitoring the geographic and temporal trends of contaminants. The purpose of this study was to determine if any relationship exists in the pattern and quantity of select contaminants found in turtle tissues relative to egg contamination. Six gravid snapping turtle females were collected from within and outside the Great Lakes basin and analyzed for congener-specific polychlorinated biphenyls (PCBs), dichlorodiphenyl-dichloroethylene (DDE), mirex and hexachlorobenzene (HCB) distributions in the fat, liver, and eggs. Preliminary data collected from five sites indicates that the pattern of congener-specific PCBs and homologs, average chlorine/biphenyl, and total PCBs are significantly correlated among snapping turtle eggs and tissues. Significant correlations were also observed for DDE, mirex, and HCB. All six turtles in this study revealed a consistent, and enhanced lower-chlorinated PCB pattern in the eggs relative to maternal adipose and liver tissues. Although these preliminary results are based on a relatively small sample size (n = 6), the significance of the relationships observed indicate that the utilization of snapping turtle eggs provides a reliable indicator of maternal contaminant burdens found in the highest environmental trophic levels.