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3A - Biomarker/Biomonitoring (TUP/158) Monooxygenase activity in turbot exposed to field-collected Cork Harbour sediments: a microcosm study. Kilemade, Michael1, Hartl, Mark1, Sheehan, David1, O'Brien, Nora1, van Pelt, Frank1, O' Halloran, John1, Mothersill, Carmel2, 1 University College Cork, Cork, Munster, Ireland2 Dublin Institute of Technology, Dublin, Leinster, Ireland ABSTRACT- High levels of persistent organic pollutants (POPs) in marine ecosystems lead to the deterioration of water quality and consequently adversely affect fish and human health. These pollutants tend to enter fish via their diet or by water-borne exposure due to their highly lipophilic nature. Marine sediments are a sink for anthropogenic waterborne POPs and therefore act as a pollution source for benthic organisms. In monitoring contamination of aquatic ecosystems, induction of monooxygenase activity in fish has been evaluated as a sensitive, early warning method. The objective of the present study was to examine the inducibility of and the relationship between the hepatic microsomal enzymes, EROD, BROD, PROD and MROD (cytochrome P450 monooxygenase activity (CYP1A)) in turbot Scophthalmus maximus, a benthic species and field-collected estuarine sediment from two sites within Cork Harbour (Whitegate and Aghada), Co. Cork, Ireland and a clean, reference site, Ballymacoda, Co. Cork. Sediment POP loadings in terms of selective PCBs, PAHs and OCPs from each site were characterised by the Marine Institute, Ireland. Following acclimation, juvenile turbot were exposed to sediments and sampled at 0, 7, 14 and 21 days. Fish were sacrificed, livers were excised and snap-frozen in liquid nitrogen and processed for measurement of CYP1A activity. Results indicated that EROD, PROD and MROD activity evidenced strong differences between the two harbour sites and the reference site but responses did not vary significantly with exposure time. BROD remained at baseline Tzero levels throughout. Key words: sediment, harbour, turbot, monooxygenase activity |
