低盐度对不同三疣梭子蟹群体幼蟹发育的影响

对野生三疣梭子蟹Portunus trituberculatus亲蟹繁育的Ⅱ期幼蟹进行低盐度胁迫,发现其120 h的半致死盐度为11.7,并比较了“黄选1号”三疣梭子蟹和低盐适应群体三疣梭子蟹在低盐度（11.7）水中和正常海水（盐度为35.0）中的存活率、变态率和生长状况.结果表明：“黄选1号”在盐度为11.7时的存活率比在正常海水中低,低盐适应群体在盐度为11.7时的存活率与在正常海水中差异不明显;在盐度为11.7的水中,两个群体幼蟹的变态率与生长指标均低于在正常海水中.试验结束时,“黄选1号”在低盐度（11.7）水中的存活率、变态率、全甲宽分别为20.00％、10.00％、（17.47±1.11） mm,在正常海水中的存活率、变态率、全甲宽分别为52.22％、53.33％、（20.43±1.21）mm;低盐适应群体在低盐度（11.7）水中的存活率、变态率、全甲宽分别为32.22％、13.33％、（17.69±0.93） mm,在正常海水中的存活率、变态率、全甲宽分别为27.98％、16.67％、（18.79±1.61） mm.研究表明,低盐适应群体抵抗低盐胁迫的能力较强,在正常海水中“黄选1号”幼蟹的存活率、变态率、全甲宽和体质量均高于低盐适应群体.

Effects of low salinity on development of juveniles in different groups of swimming crab Portunus trituberculatus

The survival rate,metamorphosis rate and growth were studied in swimming crab Portunus trituberculatus juveniles in two groups （＂Huangxuan No.1＂ and low salinity group） under low salinity of 11.7,the median lethal salinity （LD50） for 120 h based on low salinity stress experiment in the wild crab stocks.The results showed that the ＂Huangxuan No.1＂ had significantly lower survival rate at a salinity of 11.7 than that at a salinity of 35.0.The juveniles in the low salinity group,however,showed almost the same survival rate at a salinity of 11.7 as that at a salinity of 35.0.There were significantly lower metamorphosis rate and growth in the two crab groups at a salinity of 11.7 than at a salinity of 35.0.At the end of the experiment,the ＂Huangxuan No.1＂ juveniles exposed to salinity of 11.7 had survival rate of 20.00%,metamorphosis rate of 10.00%,and total carapace width of （17.47 ± 1.11）mm.However,the ＂Huangxuan No.1＂ juveniles exposed to a salinity of 35.0 showed survival rate of 52.22%,metamorphosis rate of 53.33%,and total carapace width of （20.43±1.21）mm.The swimming crab juveniles in the low salinity group exposed to a salinity of 11.7 had survival rate of 32.22%,metamorphosis rate of 13.33%,total carapace width of （17.69±0.93）mm and body weight of （0.35 ±0.06）g.The juveniles of the low salinity group exposed to a salinity of 35.0 showed survival rate of 27.98%,metamorphosis rate of 16.67%,and total carapace width of （18.79±1.61）mm.There was higher tolerance to low salinity in the juveniles of the low salinity group,and the ＂Huangxuan No.1＂ juveniles were found to be superior to the low salinity group at a salinity of 35.0 in survival,metamorphosis rate,and total carapace width.