The concentration and biomagnification of PCBs and PBDEs across four trophic levels in a marine food web

Contracting Parties to the OSPAR Convention for the Protection of the Maine Environment of the North-East Atlantic are required to undertake monitoring and assessment of both inorganic and organic contaminants. There is a requirement to assess contaminants across different trophic levels on an ecosystem-specific basis. However, this is currently constrained by the availability of relevant samples to cover the full range of trophic levels. This study investigates the variability (inter- and intra-species variation) of the concentrations and distributions of thirty-two polychlorinated biphenyl (PCB) congeners and nine polybrominated diphenyl ether (PBDE) congeners in twenty-six species covering four trophic levels from different geographic locations around Scotland. Trophic magnification factors (TMFs) were calculated using a traditional method and a balanced method for both the ICES-7 PCBs and BDE47, to refine and improve the application of TMFs to assess and predict biomagnification risk to biota in the marine environment. There were clear differences in congener percentage distribution between sample categories and species, with differences influenced by physiological processes and eco-biological parameters. Trophic magnification was found to occur for the ICES-7 PCBs and BDE47 using the traditional method, with the highest degree of trophic magnification reported for CB52. An unbalanced dataset was found to influence the calculated TMF and in some cases, the overall conclusion of the trophic transfer of PCB and PBDE congeners. The balanced method is highly recommended for calculating TMFs to ensure that the TMF is a true indication of the biomagnification potential, particularly when conducting regional comparisons for which sampling requirements are difficult to achieve.

Automated summary

This study investigated the variability of concentrations and distributions of PCB and PBDE congeners in 26 species from different locations around Scotland. The study found clear differences in congener distribution between sample categories and species, influenced by physiological processes and eco-biological parameters. Trophic magnification was observed for the ICES-7 PCBs and BDE47 using the traditional method, with CB52 showing the highest degree of magnification. The unbalanced dataset influenced the calculated trophic magnification factor (TMF) and sometimes the overall conclusions of congener biomagnification. The use of a balanced method is recommended for accurate TMF calculations, particularly in regional comparisons with difficult sampling requirements.