In the context of new oil exploration/production areas, knowledge of the biological impact of dispersed oil in the deep-sea environment is essential. Hence, the aim of this study was to perform a comparison, at atmospheric pressure (0.1 MPa) and at a high hydrostatic pressure corresponding to 1000 m depth (10.1 MPa), of lethal concentrations (LC) on a model fish, Scophthalmus maximus, exposed to chemically dispersed oil. Fish were exposed concomitantly at 0.1 and 10.1 MPa using two exposure tanks connected to the same source tank thanks to a closed circuit. Acute toxicity was evaluated at 24 h through the determination of LC10 and LC50 (respectively, 10 and 50% of mortality) calculated from measured total petroleum hydrocarbon concentrations in the water. No statistical differences were observed between the LC10 at 0.1 MPa (46.1 mg L- 1) and the LC10 at 10.1 MPa (31.0 mg L- 1), whereas the LC50 of fish exposed to 0.1 MPa (90.8 mg L- 1) was significantly higher than the LC50 at 10.1 MPa (50.9 mg L- 1). These results clearly show an increase in oil toxicity under high hydrostatic pressure. This effect may be due to synergistic effects of pressure and oil contamination on fish energetic metabolism.
Keywords: Dispersed oil; Ecobarotoxicology; High hydrostatic pressure; Hyperbaric chamber; Lethal concentrations; Model fish; Scophthalmus maximus.