Environmental Contaminants in Eggs of the Common Snapping Turtle ( Chelydra serpentina serpentina) from the Great Lakes-St. Lawrence River Basin of Ontario, Canada (1981, 1984)

Common snapping turtle eggs were collected at nesting sites from two locations in 1981 and eight locations in 1984 in Ontario, Canada, and analyzed for chlorinated hydrocarbons. Nine locations were within the Great Lakes-St. Lawrence River basin and one location, Algonquin Provincial Park, served as a control site outside the basin. Total PCBs ranged from 0.057 to 4.76 mg/kg (wet wt.) among the Great Lakes-St. Lawrence River samples. Mean total PCB concentration at Algonquin Park was 0.187 mg/kg. Eggs from Hamilton Harbour, Port Franks, Bay of Quinte/Murray Canal, and Lake St. Clair were the most contaminated among the ten sample locations. There was statistically significant variation in concentrations of all organochlorine compounds among sites. In some locations, there was high variation in contamination among clutches. A pool of eggs from Hamilton Harbour contained 67 ng/kg of 2378-tetrachlorodibenzo-p-dioxin and 14.0 ng/kg of23478-pentachlorodibenzofuran. Some dioxin congeners were present in turtle eggs at concentrations higher or equal to that in herring gull eggs from Hamilton Harbour. Comprehensive GC/MS analysis of the Hamilton Harbour eggs also revealed the presence of trace amounts of o,p-dicofol, octachlorostyrene, and toxaphene. Geographic variation in contaminant levels in snapping turtle eggs from wetlands is similar to that in spottail shiners and herring gull eggs collected in the pelagic zone of the Great Lakes. This may be due to the consumption of migrant fish by snapping turtles in nearshore wetlands.