Responses of the cytochrome P450-dependent monooxygenase and other protective enzyme systems in digestive gland of transplanted common mussel (Mytilus edulis L.) to organic contaminants in the Skagerrak and Kattegat (North Sea)

In order to determine the biological impact of contaminants in the Skagerrak and Kattegat, mussels (Mytilus edulis L.) (4.5-6 cm in length) from a clean area (Faroe Islands) were transplanted for 6-8 weeks in 1993 and 1994 to sites in the Faroe Islands (reference control), to the Skagerrak deep-water region between Norway and Sweden, and to suspected contaminant-influx sites near the Hvaler Archipelago (Norway) and Goteborg (Sweden). Similar results were obtained in both years. Whole body total polynuclear aromatic hydrocarbons (PAHs) were 57-206 % higher in M. edulis from the Skagerrak, Norway and Sweden sites (up to 62 ng g(-1) dry wt) compared with the Faroe Islands reference control, whereas no differences were seen in organochlorines (PCBs, chlordanes, DDTs, hexachlorocyclohexanes, hexachlorobenzene). Digestive gland microsomal benzo[a]pyrene hydroxylase (BPH) activity (formation of phenols) was elevated at all the contaminated sites compared with the Faroe Islands reference control (p<0.05). BPH turnover (BPH activity pmol(-1) P450) was elevated 132-288 % compared with the the Faroe Islands (p<0.05) and showed limited correlation with total PAHs (r(2)=0.58). Overall, the results are indicative of impact by PAHs and induction of the cytochrome P450 monooxygenase system. In contrast to previous studies on M. edulis exposed to higher tissue levels of PAHs or PCBs, no elevation of cytochrome P4501A-immunopositive protein (CYP1A) was detected using antibodies to fish hepatic CYP1A. Little or no differences between any sites were seen in digestive gland glutathione S-transferase (EC 2.5.1.18), superoxide dismutase (EC 1.15.1.1) and catalase (EC 1.11.1.6) activities.