Stress-induced changes of plasma antioxidants in aquacultured sea bass, Dicentrarchus labrax

Antioxidant plasma activities of ascorbate, α-tocopherol and glutathione peroxidase were analysed in adult male sea bass, Dicentrarchus labrax, in normal conditions and after hypoxia-recovery. In addition, tank measurements of temperature, pH, salinity and chlorine changes were carried out. Ascorbate and α-tocopherol were measured using a high-pressure liquid chromatography method and glutathione peroxidase activity enzymatically. Ascorbate and α-tocopherol showed a relationship with the velocity of body growing in normal and hypoxia-recovery conditions. In sea bass exposed to hypoxia, only ascorbate and α-tocopherol levels were significantly lower compared with the control group. Slope study and expression percent of antioxidants reduction after stress conditions revealed a predominant role of plasma α-tocopherol. Sea bass subjected to variations of salinity and chlorine showed a significant decrease in plasma α-tocopherol. A relationship could be suggested between antioxidant defence and fish response in aquaculture.