Responses of juvenile sea bass, Dicentrarchus labrax, exposed to acute concentrations of crude oil, as assessed by molecular and physiological biomarkers

► PAHs were found in fish after oil exposure. ► EROD increased following the 48 and 96h of oil exposure. ► A decrease of fish growth was observed 4weeks after both exposure times. ► A decrease of fish condition was observed 4weeks after 96h of oil exposure. ► Usefulness of the simultaneous use of molecular and physiological biomarkers. In the present study, juvenile sea bass were exposed for 48 and 96h to an Arabian light crude oil and their responses were assessed at the molecular and physiological levels. The aim of the study was therefore to assess (i) the short term effects of crude oil exposure by the measurement of several molecular biomarkers, (ii) the consequences of this short term exposure on fish health by using growth and condition indices measured after a decontamination period of 28 and 26d in seawater. Hydrocarbon petroleum concentrations was monitored during the 96h experiments and an increase of PAH concentrations were found in fish following both exposure times. An 7-ethoxyresorufin-O-deethylase (EROD) induction was observed after 48h of exposure, while a significant decrease in the sea bass specific growth rate in length and for the RNA:DNA ratio was observed 28d after that exposure ceased. The EROD induction doubled after the 96h exposure, and a significant increase in GST activities was observed. A significant decrease in the specific growth rates, the otolith recent growth, the RNA:DNA ratio and the Fulton’s K condition index were then observed in sea bass 26d after the 96h exposure to mechanically dispersed crude oil compared to the control. The present study shows that growth and condition indices can prove useful in assessing fish health status following an oil spill. Their complementary analysis with sensitive molecular biomarkers as EROD could improve the determination of oil spill impact on fish populations.