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 l ocations in 1981 and eight locations in 1984 in Ontario, Canada, and a nalyzed for chlorinated hydrocarbons. Nine locations were within the G reat Lakes-St. Lawrence River basin and one location, Algonquin Provin cial Park, served as a control site outside the basin. Total PCBs rang ed from 0.057 to 4.76 mg/kg (wet wt.) among the Great Lakes-St. Lawren ce River samples. Mean total PCB concentration at Algonquin Park was 0 .187 mg/kg. Eggs from Hamilton Harbour, Port Franks, Bay of Quinte/Mur ray Canal, and Lake St. Clair were the most contaminated among the ten sample locations. There was statistically significant variation in co ncentrations of all organochlorine compounds among sites. In some loca tions, there was high variation in contamination among clutches. A poo l of eggs from Hamilton Harbour contained 67 ng/kg of 2378-tetrachloro dibenzo-p-dioxin and 14.0 ng/kg of 23478-pentachlorodibenzofuran. Some dioxin congeners were present in turtle eggs at concentrations higher or equal to that in herring gull eggs from Hamilton Harbour. Comprehe nsive GC/MS analysis of the Hamilton Harbour eggs also revealed the pr esence of trace amounts of o,p-dicofol, octachlorostyrene, and toxaphe ne. 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 du e to the consumption of migrant fish by snapping turtles in nearshore wetlands.