盐度驯化、投喂和饥饿条件下盐度对缢蛏存活的影响

Effects of Salinity on Survival of Razor Clam Sinonovacula constricta Under Salinity Acclimation,Feeding and Starvation

在水温(13.8±0.5)℃下,将壳长为(5.15±0.34)cm的缢蛏(Sinonouacula constricta)放入盐度15的人工海水中暂养48 h后,置于20 L周转箱中,盐度保持在1、3、5、15、30和40(未驯化组,A组),盐度15组为对照组。再将上述暂养48 h后的缢蛏投入盐度10的水体驯化24 h后,然后投入盐度为5的水体驯化24 h,之后保持在盐度0.5、1、2、3、4和5周转箱中(驯化组,B组),盐度5为对照组。上述在盐度15的人工海水中暂养48 h后的缢蛏,保持在盐度2(接近低盐驯化组7 d的半致死浓度)中,早晚各投喂一次蛋白核小球藻(Chlorella pyrenoidosa)(投喂组,C组),以不投喂组为对照,探讨不同条件下盐度对缢蛏存活的影响。结果表明:未经低盐驯化的A组缢蛏在盐度1水体中平均死亡率(46.7±3.8)%明显高于对应驯化组(1.1±1.1)%。单因素方差分析结果表明:A组和B组缢蛏的死亡率均值分别在3~11 d和4~9 d开始出现显著性差异;C组缢蛏7 d的死亡率显著低于对照投喂组(P<0.05)。结果表明,事先经过分级低盐驯化可显著提高缢蛏在低盐度水体(1<盐度≤5)中的成活率,实验观察的合理时间为7 d,实验期间可以不进行投喂。

Razor clam(Sinonouacula constricta)with shell length of(5.15±0.34)cm acclimatized at a salinity of 15 for 48 h was placed in a 20L artificial seawater turnover box at a salinity of 1,3,5,15,30 and 40(non-domesticated group,Group A),with the control group at a salinity 15 at water temperature of(13.8±0.5)℃.The above-mentioned razor clam acclimatized at a salinity of 15 for 48 h was put into a water body with a salinity of 10 for 24 h,and then put into a water body with a salinity of 5 for 24 h,and then kept in a 0.5,1,2,3,4 and 5 turnover box(domesticated group,Group B),with the control group at a salinity of 5.The above-mentioned razor clam acclimatized at a salinity of 15 for 48 h was maintained at a salinity of 2(close to the median-lethal concentration of the low-salt domestication group for 7 days),and fed green alga Chlorella pyrenoidosa in the morning and evening(feeding group,Group C)with the control group at fasting to explore the influence of salinity on the survival of razor clam under different conditions.The results showed that the razor clam had significantly higher mortality rate in Group A(46.7±3.8)%than the razor clam in Group B(1.1±1.1)%did in water with salinity of 1.The one-way analysis of variance revealed that the significant differences in mean mortality of the razor clam was observed from 3 d to 11 d in Group A and from 4 d to 9 d in Group B,with significantly lower mortality in Group C than that in the razor clam in the feeding group(P<0.05).The findings indicated that pre-graded low-salt domestication led to significantly increase the survival rate of the razor clam in low-salinity water(1<salinity≤5),with reasonable time of 7 d for experimental observation,without feeding during the experiment.