低盐度胁迫对点带石斑鱼幼鱼消化酶、抗应激酶和存活率的影响

Effect of low salinity stress on activities of digestive and anti-stress enzymes,and survival rate of juvenile Epinephelus malabaricus

探讨了低盐度胁迫对点带石斑鱼幼鱼消化酶、抗应激酶及幼鱼存活率影响。实验设计了28.23、22.56、17.57、12.67和7.71等5个盐度梯度,实验鱼共40尾(体重20±2.32g),先放入盐度为28.23的水体中驯化10d,然后按以上梯度逐级淡化,在每个盐度梯度维持3d后取样,测定消化酶和抗应激酶等指标,并观察其活动和存活状况。结果表明,胃和肠的蛋白酶、淀粉酶活力随盐度梯度的下降显著降低(P<0.05);肝脏、肌肉和肾脏的SOD活力随盐度梯度下降呈上升趋势,肝脏、肌肉和肾脏的CAT和GSH-Px活力随盐度梯度下降呈降低趋势;鱼的活动能力从盐度梯度为17.57时开始下降,12.67时即出现幼鱼死亡现象,盐度梯度下降到7.71时,幼鱼在12h内全部死亡。说明低盐度胁迫将会严重影响点带石斑鱼幼鱼消化能力并导致鱼体自由基代谢紊乱,应激增强,最终将影响幼鱼健康生长。

Experiments were done to investigate the effect of low salinity stress on the di- gestive enzymes, anti-stress enzymes and the survival rate of juvenile Epinephelus malabaricus. The larvae were reared in seawater and the salinity was reduced from 28.23 to 22.56, 17.57, 12. 67 and 7.71 succesively in every three days. The digestive enzymes, anti-stress enzymes and the survival status were determined. The results showed that the protease and amylase activities in both stomach and intestines of the fish reduced significantly with the decrease of the salinity （P〈0.05）. The activity of SOD increased, while CAT and GSH-Px in liver, muscle and kidney declined with the decrease of the salinity. In addition, mortality appeared when salinity was 12.67, and all the juvenile fish died within 12 hours when the salinity was 7.71. Hence, the di gestive enzymes and anti-stress system of juvenile E. malabaricus were affected seriously by low salinity stress and would ultimately affect the healthy growth of juvenile fish.