大黄鱼幼鱼对低盐度的耐受性研究

通过设置盐度的突变和渐变实验研究了大黄鱼幼鱼对低盐度的耐受性.结果表明：在盐度突变实验中,将大黄鱼幼鱼直接从海水（盐度27.2）移入盐度为3～24的水中,72 h内不会导致明显死亡;从海水移入盐度为2的水中,72 h的存活率可达72%;从海水移入盐度为1的水中,3 h后开始出现死亡,24 h内大部分死亡;从海水移入淡水中,6 h内全部死亡.在盐度渐变实验中,将大黄鱼幼鱼从海水直接移入盐度为6的水中后,再以不同的幅度降低盐度,在盐度高于3时,大黄鱼幼鱼的死亡率与相应盐度的突变实验相比无明显差异;在盐度低于2时,大黄鱼幼鱼的死亡率低于相应盐度的突变实验的结果.研究表明,大黄鱼幼鱼具有较高的低盐度耐受力.

Tolerance of Young Fish of Large Yellow Croaker （Larimichthys crocea） to Low Salinity

Tolerance of young fish of large yellow croaker,Larimichthys crocea,under different low salinity conditions were studied by performing experiments of acute and gradient salinity changing.The young large yellow croaker had low lethality rates within the first 72 h after they were transferred directly from sea water（salinity of 27.2） to water with salinity from 3 to 24.A survival rate of 72% was calculated within the first 72 h after they were transferred directly from sea water to water with salinity of 2.The deaths began at 3 h after transfer and the majority of the fish had died within 24 h after they were transferred directly from sea water to water with salinity of 1;afterwards all of the fish had died within 6 h after they were transferred directly from sea water to fresh water.While the young fish of large yellow croaker were transferred directly from sea water to water with salinity of 6 and after then the water salinity declined with different speeds,their mortality had no significant difference with the results in the experiments of acute salinity changing when the water salinity was higher than 3,and their mortality was lower than that of the experiments of acute salinity changing when the water salinity was below 2.The results showed that in fact young fish of large yellow croaker are able to tolerant certain level of low salinity stress.