Distribution of organochlorine contaminants in double-crested cormorant eggs and sibling embryos

Double-crested cormorant (Phalacrocorax auritus) fresh eggs and sibling embryos at pipping were collected from a polychlorinated biphenyl (PCB)-contaminated colony in Green Bay, Wisconsin, USA. Egg contents were analyzed for organochlorine (OC) contaminants, including 15 arylhydrocarbon-active PCB congeners. In order to determine the significance of tissue removal on the subsequent estimate of contaminant burden, embryos were decapitated and the heads, yolk sac, liver, fecal sac (allantois), and carcass remainder were analyzed separately. The distribution of contaminant concentration in the embryos was yolk sac > liver > carcass > head > fecal sac. The distribution of contaminant mass in the embryos was yolk sac > carcass > liver > head > fecal sac. For example, mass of total PCBs (TPCB) was yolk sac = 58%, carcass = 31%, liver = 5%, head = 3%, and fecal sac = 1%. Eighteen additional OCs, including 13 PCB congeners, had distribution patterns similar to that of TPCB concentration and mass. Excluding the head of the embryo from the chemical analysis overestimated TPCB concentrations by 15% (16 vs 14 μg/g). In contrast, excluding the liver from the chemical analysis underestimated TPCB concentration by only 4% (13.5 vs 14 μg/g). Mean concentrations of OCs were not significantly different between fresh eggs and sibling embryos.