设施养殖条件下不同因素对拟穴青蟹幼蟹存活率的影响

Effect of Different Factors on Survival of Juvenile Crab,Scylla paramamosain,Under the Condition of Facility Culture

在水温25.2±1℃、连续充气和pH 7.8-8.3条件下，以蚊帐布和筛绢网制成网笼作为养殖设施，以7个盐度梯度、6种养殖密度和2种网衣材质的3因素多水平实验设计进行幼蟹养殖试验.结果表明：幼蟹存活率均在盐度25时最高，分别为C195.0%，C290.5%，盐度高于或低于25均有下降趋势，C1和C2在各盐度梯度组累计存活率均差异显著（p〈0.01），而在同一盐度梯度下差异不显著（p〉0.05）；C1至C2和C2至C3在盐度5、30、35时发育时间为120±2 h，而在盐度10、15、20、25时为96±2 h，同时在盐度10、15、20、25组中幼蟹蜕皮的同步性优于盐度5、30、35组.在不同密度条件下，幼蟹均在密度为637 ind/m^2时存活率最高，且C1的平均存活率（89.6%）比C2（84.5%）高，C1和C2在同一密度梯度下的存活率差异极显著（p〈0.01）.在蚊帐布和筛绢网2种材质养殖容器中，C1的平均存活率分别为90.4%和88.7%，差异不显著（p〉0.05），而C2的平均存活率分别为86.6%和82.6%，差异极显著（p〈0.01），表明C1对养殖容器材质的选择性不强.综上所述，在盐度为25，养殖密度为637 ind/m^2，蚊帐布为网衣材质的实验条件下，幼蟹生长最好，存活率可达到最高值.

Under the condition of water temperature（25.2±1℃） ,continuous aeration and pH 7.8-8.3,a 3 factor multilevel juvenile crab culture experiment were implemented with 7 salinity levels,6 cultural density and 2 rearing container textiles. The result showed that the juvenile crab had the highest survival rate （C1 95.0% ,C2 90.5%） at 25 salinity. There was a decreased trend at the salinity either lower or higher 25. The survival rate of C1 and C2 had significant differences among all salinity levels groups （p〈0.01） ,but no significant differences （p〈0.05） in the same salinity level. The intermolt period of C1 to C2 and C2 to C3 at 5,30,35 salinity was 120 ± 2 h, while at 10,15,20,25 salinity, it was 96 ± 2 h, the extent of metamorphism synchronization was more higher at 10,15, 20,25 groups than those of which at 5,30,35. Among all cultural densities , 637 ind/m^2 had the highest survival rate （90.00%） . The average survival rate of C1 （89.6%） was higher than C2 （89.6%）, and significant differences （p〈0.01） of survival rate between C1 and C2 were found at the same cultural density. The survival rate of juvenile crab C2 in mosquito net and bolting-silk container were 88.50 % and 85.65 % respectively, the survival rate of mosquito net （90.4 % ） and bolting-silk（88.7 %）had no significant differences （p〉0.05） ,while the survival rate of C2 in mosquito net （86.6%） and bolting-silk（82.6%） had significant differences（p〈0. 01）, which suggested that C1 was not much selective to the textile of container. In conclusion,the optimum condition was 25 salinity,637 ind/m^2 and mosquito net container.