DISTRIBUTION OF ORGANOCHLORINE CONTAMINANTS IN DOUBLE-CRESTED CORMORANT EGGS AND SIBLING EMBRYOS

Double-crested cormorant (Phalacrocorax auritus) fresh eggs and siblin g embryos at pipping were collected from a polychlorinated biphenyl (P CB)-contaminated colony in Green Bay, Wisconsin, USA. Egg contents wer e analyzed for organochlorine (OC) contaminants, including 15 arylhydr ocarbon-active PCB congeners. In order to determine the significance o f tissue removal on the subsequent estimate of contaminant burden, emb ryos were decapitated and the heads, yolk sac, liver, fecal sac (allan tois), and carcass remainder were analyzed separately. The distributio n of contaminant concentration in the embryos was yolk sac > liver > c arcass > head > fecal sac. The distribution of contaminant mass in the embryos was yolk sac > carcass > liver > head > fecal sac. For exampl e, mass of total PCBs (TPCB) was yolk sac = 58%, carcass = 31%, liver = 5%, head = 3%, and fecal sac = 1%. Eighteen additional OCs, includin g 13 PCB congeners, had distribution patterns similar to that of TPCB concentration and mass. Excluding the head of the embryo from the chem ical analysis overestimated TPCB concentrations by 15% (16 vs 14 mu g/ g). In contrast, excluding the liver from the chemical analysis undere stimated TPCB concentration by only 4% (13.5 vs 14 mu g/g). Mean conce ntrations of OCs were not significantly different between fresh eggs a nd sibling embryos.