低盐度胁迫对拟穴青蟹初期稚蟹成活率的影响

Effects of Low Salinity Stress on Survival Rate of Juvenile Mud Crab

摘要: 实验以拟穴青蟹(Scylla paramamosain)初期稚蟹为研究对象，采取盐度骤降和渐降方式，设计不同盐度梯度，观察稚蟹的成活率，旨在探索稚蟹对盐度的适应能力。结果表明：初期稚蟹耐低盐度胁迫的能力强，从自然海水盐度(S23)骤降至18和13，又从13骤降至10和5，均维持在80%以上成活率，变态率在67%以上，组间无显著差异(p > 0.05)，稚蟹适宜盐度范围扩大至下限值5，稚蟹变态成活率与盐度的关系符合幂函数曲线方程，y = 0.2309Χ − 0.5894，(R2 = 0.98)。稚蟹C5的12 h、24 h、48 h和C4的96 h半致死盐度(LS50)分别为0.017、0.150、0.173和0.236。种蟹对盐度适应能力具有遗传性，生活在盐度较高的海南种蟹繁育的稚蟹与三门湾种蟹选育后繁育的子代对盐度的适应能力存在显著差异(p < 0.05)，选育的蟹适应低盐度环境的能力更强。通过低盐度驯化，拟穴青蟹可以在盐度0.20的环境中生长，大大拓展青蟹养殖区域空间。

Abstract: In order to explore the adaptability of juvenile mud crabs to salinity, the experiment designed dif-ferent salinity gradients and observed the survival rate of juvenile mud crabs. The result shows that: The juvenile mud crabs had a strong ability to tolerate low salinity stress in the early stage. The levels of seawater salinity were S23, S18, S13, S10 and S5. The survival rate of juvenile crabs was above 80%, the metamorphosis rate was above 67%, and there was no significant difference between groups (p > 0.05). The salinity that juvenile mud crabs adapt extends to the lower limit of 5. The relationship between metamorphosis rate and salinity of juvenile crab accords with the power function curve equation, y = 0.2309X − 0.5894 (R2 = 0.98). The semilethal salinity (LS50) of juvenile crab C5 at 12 h, 24 h, 48 h and C4 at 96 h was 0.017, 0.150, 0.173 and 0.236, respectively. The adaptability of mud crabs to salinity was inherited. The adaptability to low salinity was sig-nificant difference between the offspring of mud crabs bred from Hainan province and Sanmenwan Zhejiang province (p < 0.05), and the breeding crab is more capable of adapting to low salinity environment. Through low salinity domestication, the mud crab can grow in a salinity of 0.2, which can greatly expand the area of mud crab culture.