The effect of salinity on growth rate, survival and swimbladder inflation in gilthead seabream, Sparus aurata, larvae

The effects of salinity (15-40 p.p.t. salinity; 450-1200 mOsm kg^-1) on growth, survival and swim bladder (SB) inflation in gilthead seabream, Sparus aurata, were evaluated. Over the salinity range tested, 1-32 day old seabream larvae were found to be osmotic regulators. Within the range tested, 1 day old larvae maintained an osmotic pressure of 224 mOsm kg^-1, significantly lower than 410 mOsm kg^-1 in 13 and 24 day old larvae. In addition, water content in larvae was negatively correlated with age, being over 86% in 4 day old larvae and 83% in 32 day old larvae. A negative relationship was found between salinity and survival; as the rearing salinity decreased from 40 to 25 p.p.t., survival increased from 5.3 to 18.6%. Larval final dry weight (DW) and wet weight (WW) were over 16% higher at 25 than 40 p.p.t. salinity. Finally, reduced salinity induced a significant increase in the rate of SB inflation; 65 to 92.5% in 40 and 25 p.p.t. acclimated larvae, respectively.