盐度对中国鲎幼鲎生长、蜕壳、Na+-K+-ATP酶活性、免疫指标和抗氧化能力的影响

人工增殖放流是恢复鲎资源最有效、最迅速的方法, 而了解和掌握环境因子对中国鲎(Tachypleus tridentatus)幼鲎生长状况的影响规律, 进而选择适宜放流的时间和海区, 是保证人工放流得以成功的关键。本文在实验室条件下, 研究了不同盐度(5‰、10‰、15‰、20‰、25‰、30‰、35‰、40‰)对中国鲎幼鲎成活率、蜕壳率、蜕壳增重率、Na⁺-K⁺-ATP酶活性、免疫酶活性、抗氧化酶活性等的影响, 探讨了不同盐度水平下中国鲎幼鲎生长、蜕壳、渗透调节能力、机体免疫力和抗氧化能力等的变化。养殖试验持续56d, 结果表明: 不同盐度对中国鲎幼鲎的成活率、蜕壳率、二龄幼鲎均重及蜕壳增重率均有显著影响(P<0.05), 且均随盐度升高呈先升高后降低的趋势; 蜕壳率和蜕壳增重率与盐度的回归分析均表明, 中国鲎幼鲎蜕壳与生长的最适盐度分别为24.10‰和24.94‰; 一龄和二龄幼鲎的Na⁺-K⁺-ATP酶活性均随盐度的升高呈先显著升高后显著降低趋势(P<0.05); 35‰和40‰盐度试验组一龄幼鲎的酸性磷酸酶(acid phosphatase, ACP)活性显著高于其他试验组, 而5‰盐度试验组一龄幼鲎的碱性磷酸酶(alkaline phosphatase, AKP)活性显著低于25‰试验组(P<0.05) ; 盐度对二龄幼鲎的ACP、AKP和溶菌酶(lysozyme, LZM)活性均没有显著影响(P>0.05); 35‰和40‰试验组一龄幼鲎的过氧化氢酶(catalase, CAT)活性显著高于盐度较低试验组(P<0.05); 二龄幼鲎的谷胱甘肽过氧化物酶(glutathione peroxidase)活性随着盐度的升高而升高, 盐度10‰试验组显著低于30‰和40‰试验组(P<0.05)。研究结果显示盐度对中国鲎幼鲎生长、蜕壳、Na⁺-K⁺-ATP酶活性、免疫指标和抗氧化能力均有显著影响, 蜕壳最适宜的盐度在24‰~25‰左右, 盐度过高或过低都将引起幼鲎生长率和成活率降低, 渗透调节能力、免疫力和抗氧化力显著下降。

Effects of salinity on growth,molting, Na+-K+-ATP enzyme activities,immune index,and antioxidantion of juvenile Chinese horseshoe crab,Tachypleus tridentatus

Artificial proliferation and release is the most effective and rapid method to restore Limulus resources. Understanding and grasping the influence of environmental factors on the growth of juvenile Chinese horseshoe crab (Tachypleus tridentatus), and then choosing a suitable time and sea area for release are the key steps to ensure the success of manual release. Under laboratory conditions, we studied the effects of different salinity (5‰, 10‰, 15‰, 20‰, 25‰, 30‰, 35‰, and 40‰) on the survival rate, molting rate, molting weight gain rate, Na⁺-K⁺-ATPase activity, immune enzyme activity, and antioxidant enzyme activity of juvenile Chinese horseshoe crab. The changes of growth, molting, osmotic adjustment, immunity, and antioxidation of the juvenile horseshoe crab at different salinity levels were recorded. The culture experiment lasted for 56 days. The results showed that different salinity levels significantly affected the survival rate, molting rate, average weight of the 2nd instar horseshoe crabs, and molting weight gain rate of the juvenile horseshoe crab (P< 0.05), which increased at first and then decreased with increasing salinity. Regression analysis of molting rate, molting weight gain rate and salinity showed that the optimum salinity for molting and growth of young horseshoe crab were 24.10‰ and 24.94‰, respectively. The Na⁺-K⁺-ATPase activities of the 1st and 2nd instar horseshoe crabs increased at first and then decreased significantly with the increase of salinity (P< 0.05). The acid phosphatase (ACP) activities of the 1st instar larvae in the 35‰ and 40‰ test groups were significantly higher than those in the other test groups, while the alkaline phosphatase (AKP) activities of the 5‰ test group were significantly lower than those in the 25‰ test group (P< 0.05). The activities of ACP, AKP and lysozyme (LZM) of the 2nd instar larvae did not change significantly under different salinity conditions (P> 0.05). The catalase (CAT) activities of the 1st instar larvae in 35‰ and 40‰ test groups were significantly higher than those of low-salinity test groups (P< 0.05). And the glutathione peroxidase (GSH-Px) activities of the 2nd WHAT tended to increase with the increase of salinity, and those in 10‰ test group were significantly lower than those in 35‰ and 40‰ test groups (P< 0.05). We show that salinity had a significant effect on growth, molting, Na⁺-K⁺-ATPase activity, immune index, and antioxidation of the juvenile horseshoe crab. The optimum salinity for molting was between 24‰ and 25‰. Too high or too low salinity will cause the growth rate, survival rate of juvenile silver carp, the osmotic adjustment ability, immunity, and antioxidation of the juvenile horseshoe crab to decrease significantly.