Histological, growth and 7-ethoxyresorufin O-deethylase (EROD) activity responses of greenback flounder Rhombosolea tapirina to contaminated marine sediment and diet

Pathological abnormalities and mixed function oxygenase (MFO) enzyme change s are frequently used as indicators of anthropogenic contaminant exposure a nd effect. However, there is a paucity of research investigating the effect s of contaminated sediment on native Australian benthic teleosts. As part o f an ecotoxicological assessment of contaminated marine sediments in northe rn Tasmania, CYP1A induction, histological and growth response of the green back flounder, Rhombosolea tapirina, exposed to contaminated marine sedimen ts were examined. Hatchery reared flounder were exposed to reference sedime nt, contaminated sediment or contaminated sediment and diet for 6 weeks. CY P1A induction, using the ethoxyresorufin-O-deethylase (EROD) assay, and the histological and growth response in the flounder were examined on cessatio n of the exposure trial. Significant differences were found between treatme nts in histological, growth and EROD response. Exposure to contaminated sed iment and diet elicited a multi-organ histological response: principally pa rtial and total epidermal erosion and multifocal necrosis of the liver. The prevalence of total epidermal erosion was greatest with exposure to distur bed contaminated sediment (66.65 +/- 16.65%). The prevalence of multifocal necrosis of the liver was greatest with exposure to contaminanted sediment and diet (66.65 +/- 16.65%). Growth reduction, measured as percentage growt h inhibition, was evident in flounder exposed to contaminated sediment and diet (18.2 +/- 11.99%). Additionally, exposure to contaminated sediment and diet elicited elevated induction of the EROD liver detoxification enzyme ( 139.65 +/- 24.22 pmol/min/mg protein) compared to exposure to contaminated sediment and non-contaminated diet (6.25 +/- 0.81 pmol/min/mg) indicating t he presence and potential bioavailability of xenobiotics via food. Further, more inhibited growth and histological alteration associated with exposure to contaminated sediment and diet suggest contaminants in Deceitful Cove s ediment are cytotoxic. (C) 2001 Elsevier Science B.V. All rights reserved.