盐度对条纹锯鮨(Centropristis striata)仔鱼的活力、开口、摄食的影响

观察研究了10个盐度梯度(7、12、17、22、27、32、37、42、47和52)对条纹锯鮨(Centropristis striata)仔鱼的活力、开口和摄食情况的影响,记录分析其在不同盐度条件下不投饵存活系数、开口率、摄食率及摄食强度等指标.结果显示,盐度对条纹锯鮨仔鱼的活力、摄食及存活有明显影响,其存活和摄食的适宜盐度范围为12-37,最适盐度范围为27-32.盐度低于12时,仔鱼存活率、开口率和摄食强度随盐度的降低而降低,盐度高于37时,仔鱼存活率、开口率及摄食强度则随盐度的升高而降低.不同盐度条件下,条纹锯鮨仔鱼SAI值的波动范围为0.034-6.401,盐度为12-37的实验组与7、42、47、52实验组的SAI值存在显著性差异(P＜0.05),盐度为32时,仔鱼的SAI 值最大,为6.041,SAI值与盐度之间符合三次曲线函数关系,其表达式为y=-5.894+1.155x-0.034x2+0.000x3,R2 =0.895,其中,y代表SAI,x代表盐度.盐度为7、42、47和52时,仔鱼的存活率均低于50％,盐度为52、47时,仔鱼在第3、4天存活率分别降为0.盐度为22、27、32时,培育至第5天,仔鱼的存活率均在80％以上.盐度在17-37范围内,仔鱼开口率为60％-85％,且仔鱼均能较好摄食,盐度为32时,仔鱼开口率达到最大值,为85％,仔鱼摄食亦达到最佳状态,摄食率为85％,8日龄仔鱼摄食强度为5.45个轮虫/尾.

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

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+l.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.