Organochlorine bioaccumulation and trophic transfer model for the pilot whale in the northwest Atlantic

The goals of this project were: (1) to determine the level of organochlorine exposure to pilot whales; (2) to identify tissue and individual bioaccumulation patterns, and (3) to develop a predictive model to approximate contaminant bioaccumulation into blubber. Samples from eighteen pilot whales beached in 1990--91 on Cape Cod, MA were analyzed by GC/ECD and GC/MS for polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAHs). Individual congeners and total PCBs were identified and found to be high (ppm range) in several individuals. Blubber and liver differences in metabolizable PCB congeners correlate with differences in CYP 1A abundance and activity in mature vs. immature animals. ANOVA and cluster analyses were performed to identify specific bioaccumulation patterns. Pod or exposure conditions appear to be the most important factor in bioaccumulation in these whales. Maturity level, gender, and metabolizability also seem to influence bioaccumulation in various tissues. These patterns were applied in the development of a steady state mass balance model, which focuses on exposure differences rather than metabolic and gender influences. Using a range of environmental contaminant concentrations for seawater, plankton, squid and fish, the model`s low range of output values best approximated blubber residues.