The objective of this study was to examine if natural variations in the quantity of phytoplankton‐derived particulate and dissolved organic carbon influences the accumulation of polychlorinated ...biphenyls (PCBs) in the tissues of Baltic Sea blue mussels (Mytilus edulis L.). In a laboratory flow‐through experiment we exposed M. edulis to the technical PCB mixture Aroclor® 1248 for 21 d at three different enrichments of the unicellular green algae Chlamydomonas sp., 0.10, 0.16, and 0.32 mg particulate organic carbon (POC)/L. Tissue and water concentrations were determined for seven PCB congeners (International Union of Pure and Applied Chemistry IUPAC 52, 101, 105, 118, 138, 153, and 180), and 21‐d bioaccumulation factors were calculated against total water concentrations. Contrary to what would be expected, an increase in algae enrichment from 0.10 to 0.32 mg POC/L resulted in an enhanced PCB accumulation by a factor of approx. 2. This increase in PCB accumulation was more pronounced for PCB congeners with lower hydrophobicity. These observations have implications for the design of laboratory accumulation studies and potentially for PCB accumulation and cycling in field populations of suspension‐feeding mussels in response to changes in eutrophication status.
