ELEVATION OF HEPATIC MONOOXYGENASE ACTIVITY IN THE DAB (LIMANDA-LIMANDA L) IN RELATION TO ENVIRONMENTAL CONTAMINATION WITH PETROLEUM-HYDROCARBONS IN THE NORTHERN NORTH-SEA

Dab (Limanda limanda L.) were caught at various distances from a group of oil platforms in the northern North Sea. Hepatic ethoxyresorufin-O -deethylase (EROD) and cyanoethoxy-coumarin-O-deethylase (cECOD) activ ity were elevated in both male and female fish caught close to the pla tforms. This effect was more marked in females which showed a 10-20-fo ld increase in activity compared to a Lt-fold increase in males for bo th EROD and cECOD. Both aliphatic and aromatic hydrocarbon analyses we re carried out to determine the extent of sediment contamination at ea ch trawling site and to measure the contamination of the livers of fis h caught at each site. The results show significant contamination of s ediments with base oil, unresolved mixtures of aliphatics and n-alkane s close to the platform. However, there was not a significant relation ship between sediment contamination and levels of the monooxygenase en zymes measured in the livers of dab. In contrast, the concentrations o f both aliphatic and aromatic hydrocarbons in the liver showed a signi ficant negative regression to distance from the platform. Examination of the relationship between liver contamination and the levels of both EROD and cECOD showed a significant positive correlation for all grou ps of hydrocarbons measured and that this was most significant for the 5-6-ring aromatics.