CHLORINATED HYDROCARBONS IN EARLY-LIFE STAGES OF THE COMMON SNAPPING TURTLE (CHELYDRA-SERPENTINA SERPENTINA) FROM A COASTAL WETLAND ON LAKE-ONTARIO, CANADA

To assess intra-clutch variation in contaminant concentrations in eggs , and to investigate the dynamics of chlorinated hydrocarbon accumulat ion in embryos of the common snapping turtle (Chelydra serpentina), co ncentrations of p,p'-DDE, hexa-chlorobenzene, trans-nonachlor, cis-chl ordane, and six PCB congeners were measured in eggs, embryos, and hatc hlings. Samples were collected from Cootes Paradise, a wetland at the western end of Lake Ontario, Ontario, Canada. The intra-clutch variati on in chlorinated hydrocarbon concentrations within four snapping turt le clutches was determined by analyzing the first, last, and middle fi ve eggs oviposited in the nest. The first five eggs had the highest me an concentrations of all chlorinated hydrocarbons (wet weight basis), wet weight, and egg diameter. On a lipid weight basis, the first five eggs contained the highest concentration of all compounds except total PCBs and cis-chlordane. The concentration of cis-chlordane (lipid wei ght basis) was the only parameter measured that was significantly diff erent among the three sets of eggs. At hatching, snapping turtles with out yolk sacs contained from 55.2 to 90.5% of the absolute amount of o rganochlorine compounds measured in the egg at oviposition. Eighteen d ays after hatching, the body burden of PCBs and pesticides decreased t o 45.3 to 62.2% of that in the fresh egg. The accumulation of organoch lorine chemicals in embryonic turtles peaked at or just before hatchin g and then declined thereafter, which is consistent with trends report ed in developing sea turtles, fish, and birds.