盐度渐变过程对黄条鰤(Seriola aureovittata)幼鱼渗透调节的影响

为了解盐度渐变对黄条鰤(Seriola aureovittata)渗透调节的影响,设置自然海水(对照组盐度为29),5,10,15,20,35六个盐度梯度,并对不同盐度下幼鱼鳃丝Na+/K+-ATP 酶活力、离子浓度、渗透压进行了检测和分析。结果显示:在盐度5~35,黄条鰤尿、血清、血浆的渗透压均随盐度升高而升高,盐度为35时渗透压均为最高,其中尿的渗透压显著高于血清和血浆渗透压。在盐度从29下降的过程中,鳃丝Na+/K+-ATP酶活力、离子浓度、渗透压呈现相似的变化规律,都随着盐度的降低而呈现总体下降的趋势;盐度从29升高到35时,各检测指标中仅有尿和血浆的K+ 含量无显著变化(P >0.05),其余均显著升高(P <0.05)。实验结果表明,黄条鰤生存和繁衍的自然海水盐度29是幼鱼存活的适宜盐度,在略低的盐度20~29均能较快适应,说明在盐度渐变过程中,黄条鰤幼鱼对外界盐度变化有较强的调节能力。

Effects of Gradual Salinity Change on Osmotic Regulation of Juvenile Yellowtail Kingfish (Seriola aureovittata)

Seriola aureovittata is a kind of seawater fish with important ecological and economic value. In order to understand the influence of gradual salinity change on osmotic regulation of juvenile Seriola aureovittata, 6 salinity gradient points are set up, which are the natural seawater with salinity of 29 (i.e. the control group) and the seawater with salinity of 5, 10, 15, 20 and 35 respectively, and the gill Na⁺/K⁺ATPase activity, ion concentration and osmotic pressure of the juvenile Seriola aureovittata are detected and analyzed under the conditions of different salinity.In the process of salinity decreasing from 29, the gill Na⁺/K⁺ATPase activity, the ion concentration and the osmotic pressure present a similar law, that is, all showing an overall downward trend with the decreasing of salinity. When salinity goes up from 29 to 35, only the contents of K⁺ in urine and plasma show no significant changes (P>0.05) and all the rest detected indexes are increased significantly (P<0.05). All these results have revealed that the salinity 29 of the natural seawater for Seriola aureovittata to survive and propagate is an optimal salinity for juvenile Seriola aureovittata to survive. In the case of slightly lower salinity 20~29 the juvenile fishes can also adapt quickly. All these indicate that in the process of salinity change the juvenile Seriola aureovittata has strong adjusting ability to the change of external salinity.