| Polychlorinated biphenyls (PCBs) are toxic industrial chemicals that have been detected at very high concentrations in apex predators, such as marine mammals. Using two bioaccumulation models for marine mammals, this thesis examined the bioaccumulation of PCBs in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary (Quebec, Canada), and harbour seals (Phoca vitulina) from The Strait of Georgia (British Columbia, Canada) and Puget Sound (Washington, USA). We determined that female lipid dynamics, nursing strategies, birthing frequency, and PCB biotransformation were the major factors influencing PCB concentrations within a population. Beluga claves and adult male seals were determined to be the most at risk from the negative health affects associated with high PCB concentrations. Model simulations predicted that PCB concentrations in harbour seals from Puget Sound were above immunosuppression thresholds for marine mammals. We concluded current tissue residue guidelines established by Environment Canada for PCBs do not adequately protect marine mammals.;Keywords. bioaccumulation-modelling, St. Lawrence estuary, Puget Sound, coastal British-Columbia, beluga whales, harbour seals, polychlorinated biphenyls, lactation, contamination, immunotoxicity. |
