2.1 Sea bass husbandry and treatment
European sea bass juveniles were reared at Ifremer Station at Palavas-les-flots (Hérault, France) in recirculating seawater (SW; osmolality: 1208 mOsm.kg−1, Na+: 515 mmol.L−1, Cl: 737 mmol.L−1) under a 12/12 h light/dark photoperiod at 20 °C. At the age of 8 months (13.59 ± 0.12 cm, 32.19 ± 2.62 g), half of the fish were transferred to brackish water (BW; osmolality: 475 mOsm kg−1) for 24 h and then transferred to dechlorinated tap fresh water (FW; osmolality: 8 mOsm.kg−1, Na+: 2 mmol.L−1, Cl: 3.5 mmol.L−1) for two weeks. The remaining fish were transferred from SW to SW as controls. Pellet food (Le Gouessant, France) was proposed daily to fish. After the 2-week salinity challenge, 5 fish per condition were killed using a 100 ppm lethal dose of benzocaine before immediate tissue sampling.