ANTIOXIDANT ENZYMES IN LIVER OF DAB LIMANDA-LIMANDA FROM THE NORTH-SEA

During the Bremerhaven Workshop, antioxidant enzyme activities were measured in liver of dab Limanda limanda from 7 stations along a gradient of decreasing organic and metal pollution from Heligoland to the Dogger Bank, and at 3 stations close to and distant from an abandoned drilling site, in the German Bight of the North Sea. Activities of catalase and glutathione peroxidase were higher near to Heligoland, consistent with higher levels of pollution. Catalase and superoxide dismutase (SOD) activities were also high at the Dogger Bank, but the reasons for this are unknown. SOD activity showed a distinct U-shaped profile along the contaminant gradient, indicating effects of factors other than pollution alone. Putative DT-diaphorase (dicumarol-inhibitable NADPH-dependent dichlorophenolindophenol [DCPIP] reductase) activity was higher near the drilling site, but the characteristics and significance of this enzyme are not well understood. The case for using antioxidant enzymes as biomarkers for environmental oxidative stress is therefore as yet unproven, but merits further study.