Abstract

Biomarkers have been tested in order to address the most suitable battery for determining adverse effects of crude oil spills on marine invertebrates. An oil spill with increasing degrees of severity was simulated by mixing crude oil (0%, 0.5%, 2%, 8%, 16%, 32%) with sediment. Carcinus maenas and Ruditapes philippinarum were exposed to this sediment for seven days with the aim of comparing their applicability in biomonitoring studies. Four biomarkers including ethoxyresorufin O-deethylase (EROD), glutathione S-transferase (GST), glutathione peroxidase (GPx) and lipid peroxidation (LPO) were analysed in gill and digestive gland tissues of clams; and in gill and hepato-pancreas tissues of crabs. EROD, GST and GPx enzymatic activities were significantly induced in gill and digestive gland tissues of clams when increasing oil concentrations (p<.01). In crabs all the biomarkers were significantly activated in gill tissues, whereas EROD and LPO activities were induced only in hepato-pancreas tissues (p<.01). Gill and digestive gland in clams and gill in crabs were found to be the most reliable tissues for analysis of biomarkers. The biomarkers selected are thus considered suitable for assessing toxicity of sediments after a marine crude oil spill accident. Both species were found to be sensitive and suitable for biomonitoring purposes.