Biological Parameters Towards Polycyclic Aromatic Hydrocarbons Pollution: A Study with Dicentrarchus labrax L. Exposed to the Model Compound Benzo(a)pyrene

The objective of the present study was to investigate the short-term effects of benzo(a)pyrene (BaP) on juvenile sea bass (Dicentrarchus labrax L.) using a multiparameter approach. At the end of the 96 h of exposure to a range of BaP concentrations (2-256 mu g l(-1)) in laboratorial conditions, a suite of biomarkers involved in biotransformation pathways, oxidative stress and damage, neurotransmission and energetic metabolism were analysed. Levels of BaP metabolites in bile and BaP-type compounds in tissues were also included as biomarkers of exposure, and the post-exposure swimming velocity was used as a toxicity endpoint at a higher level of biological organisation. In addition, a time-series experiment on the levels of bile BaP metabolites was also performed. Increased levels of BaP metabolites in bile and BaP-type compounds in liver and brain of exposed fish were found, indicating BaP uptake, metabolisation and distribution by different tissues. BaP induced oxidative stress and damage, but no significant effects on the post-exposure swimming velocity, neurotransmission and energetic pathways were found. An increase in the levels of BaP metabolites in bile over time was also observed, reaching a threshold similar at all the concentrations tested. Overall, this integrative multiparameter study reflecting different biological responses of D. labrax was suitable to assess the effects caused by the short-term exposure to BaP and may be useful in the marine environmental risk assessment of polycyclic aromatic hydrocarbons pollution. The observed toxic effects also highlight the relevance of short-term exposure to relatively high concentrations of chemicals, as can occur in the case of punctual heavy chemical releases, such as oil spills in the marine environment.