Evaluation of trophic magnification and ecological risk of persistent toxic substances by integration of bio-geochemistry and numerical analysis

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We analyzed PCBs, brominated flame retardants(PBDEs and HBCDs) and trace elements accumulated in marine organisms at various trophic levels from open waters around Japan and off-California to evaluate their contamination status, ecological effect and trophic magnification in the food webs. Among the areas surveyed, considerable contamination of HBCDs was found in the Seto-Inland Sea and off-Miyagi. In finless porpoises from the Seto-Inland Sea, concentrations of PCBs in liver trematodeinfected individuals were significantly higher than those in non-infected ones, implying their possible immune depression. Considering the results of carbon and nitrogen isotope analyses and other biological and physicochemical parameters, nutrients cycles and species structures of each food web and isomer specific metabolism/excretion by organisms as well as their trophic levels can be suggested as key factors for the food web magnification.