LIVER MICROSOMAL MONOOXYGENASE INDUCTION IN WINTER FLOUNDER (PSEUDOPLEURONECTES-AMERICANUS) FROM A GRADIENT OF SEDIMENT PAH CONCENTRATIONS AT SYDNEY-HARBOR, NOVA-SCOTIA

Winter flounder (Pseudopleuronectes americanus) were sampled in summer 1989 and 1990 in Sydney Harbour, Nova Scotia, along a gradient of sed iment polynuclear aromatic hydrocarbon (PAH) concentrations arising fr om industrial contamination; an uncontaminated bay nearby was used as a reference site. Hepatic mono-oxygenase activity, estimated by measur ements of catalytic activity and by immunochemical analysis of cytochr ome P-450 1A, increased with sediment PAH concentrations; the extent o f induction between the reference and the most contaminated sites rang ed up to 50-fold. Cyanoethoxycoumarin O-de-ethylase activity was at le ast as sensitive an indicator of mono-oxygenase induction as ethoxy-re sorufin O-de-ethylase or benzo(a)pyrene hydroxylase, and all three enz yme activities were well correlated with cytochrome P-450 1A concentra tions and with sediment PAH concentrations.