Biomonitoring of oil spill in a boreal archipelago by xenobiotic biotransformation in perch (Perca fluviatilis).

The effect of the accidental oil spill (250 tons) in a boreal archipelago (Gulf of Bothnia, Vaasa, Finland) on xenobiotic metabolism of local perch (Perca fluviatilis) was monitored for 1.5 years. The monooxygenase (benzo[a]pyrene, 7-ethoxycoumarin O-deethylase, 7-ethoxyresorufin O-deethylase) and conjugation (UDPglucuronosyltransferase, glutathione S-transferase) activities of perch liver were determined from control areas and those areas where oil had spilled. Only a slight induction in monooxygenase activities was seen in perch caught near the oil spill 4 months after the accident. The induction of monooxygenase activities detected with the fuel oil in laboratory experiments was, however, clear. After a single dose, it rose rapidly and quickly disappeared. Conjugation enzyme activities were not affected in the laboratory.