Effects of Salinity on the Survival and Feeding of Centropristis striata Larvae

Abstract:

Here we investigated the effects of salinity gradients (7, 12, 17, 22, 27, 32, 37, 42, 47, and 53) on the survival, the first feeding and feeding of larval Centropristis striata. The first feeding rate (FFR%), the feeding rate and the feeding intensity of early larvae were also recorded and analyzed. Newly-hatched larvae were used in the starvation test to measure the survival activity indices (SAIs) at different salinities. The results suggested that salinity had strong effects on the survival and feeding of larvae. The suitable salinity for newly- hatched larvae was 12–37, and the optimum range was 27 to 32. The survival rate, the first feeding rate and the feeding intensity were reduced when salinity was below 12 or above 37. The SAI of newly-hatched larvae varied between 0.034 and 6.401 according to the salinity. When the salinity was between 12 and 37, the corresponding SAIs were significantly different from those at salinities 7, 42, 47 and 52 (P﹤0.05). The SAI was the highest (6.041) at salinity 32. The relationship between SAI (y) and salinity (x) could be described as y = –5.894+1.155x–0.034x2+0.000x3, R2 =0.895. When the salinities were 7, 42, 47 and 52, the survival rate of larvae was below 50%. There was no survival after a 3-day treatment at salinity 52, or after 4 days at salinity 47. After a 5-day treatment at salinities 22, 27 and 32, the survival rate was above 80%. At salinity 17 to 37, the first feeding rate varied between 60% and 85%, and the maximum (85%) appeared at salinity 32. The highest feeding rate (85%) was also observed at this salinity, and the feeding intensity was 5.45 rotifers per larvae on Day 8.