长期低盐胁迫对梭鱼生长及生理的影响

Effects of Long Time Low Salinity on the Growth and Physiology in the Juvenile of Liza haematocheila

为研究盐度对梭鱼幼鱼生及生理指标的影响,在水温19.2~22.1℃,将体质量为(8.78±1.67)g的梭鱼幼鱼在盐度为0、5.0、10.0、15.0、20.0、25.0的室内养殖桶内(200 L)饲养6周。结果表明:淡水可显著抑制梭鱼的生长(P<0.05),而盐度10和盐度15的水体盐度可显著促进梭鱼的生长及摄食情况(P<0.05)。对梭鱼幼鱼的低盐生理适应机制研究发现,其渗透调节相关激素(GH,COR,PRL)对盐度敏感,GH表达水平与盐度大小呈正相关;COR的变化趋势与GH几乎一致而PRL浓度与盐度梯度呈负相关。符合大多数鱼类中,GH、COR为高盐适应激素,而PRL为低盐适应激素的普遍规律。梭鱼幼鱼的抗氧化系统对盐度胁迫的响应较为一致,肝脏SOD、CAT及MDA的活性随着盐度的增加都有着先下降后上升的趋势;梭鱼幼鱼脾脏AKP活性随着盐度的增加呈现倒“U”型的变化,且在盐度15时AKP活性最高。因此,梭鱼幼鱼在低盐度条件下生长较快、饵料系数低,同时也具备较好的生理指标,其最佳适应盐度在15左右。

In this study,the effects of long time low salinity on the growth and physiology in the Liza haematocheila were studied.Juvenile L.haematocheila with a body mass of 8.78±1.67 g were raised for 6 weeks in indoor breeding barrels with salinity of 0,5.0,10.0,15.0,20.0 and 25.0 in the water temperature of 19.2-22.1℃.The results showed that fresh water could significantly inhibit the growth of L.haematocheila(P<0.05),while the water salinity of 10 and 15 could significantly promote the growth and feeding situation(P<0.05).Studies on the physiological adaptation mechanism of low salt in juvenile L.haematocheila showed that the osmotic regulation related hormones(GH,COR,PRL)were sensitive to salinity,and the expression level of GH was positively correlated with salinity.The variation trend of COR was almost the same as that of GH,while the concentration of PRL was negatively correlated with the salinity gradient.In most fish,GH and COR are high-salt adaptive hormones,while PRL is low-salt adaptive hormones.The antioxidant system of L.haematocheila showed a consistent response to salinity stress,and the activity of SOD,CAT and MDA in liver decreased first and then increased with the increase of salinity.The activity of AKP in the spleen of juvenile L.haematocheila showed an inverted"U"pattern with the increase of salinity,and AKP activity was the highest at the salinity of 15.Therefore,the juvenile of L.haematocheila grow faster and feeding better under the condition of low salinity.At the same time,they also have better physiological indexes,and the best adaptability to salinity is around 15.