盐度对透明溞存活、生长和繁殖的影响

采用试验生态学方法,在恒温(20±1)℃条件下,研究盐度变化对透明溞存活、生长和繁殖的影响。试验结果显示,透明溞的24 h和48 h半致死盐度分别为4.16和2.67,安全盐度为0.36。透明溞的产前发育期和有效积温随盐度上升而增加;体长增长率随盐度的升高先升后降,存活时间和内禀增长率随盐度的升高而下降。盐度对透明溞生存、生长及繁殖的影响显著(P<0.05),0.5盐度组的透明溞壳刺长显著大于对照组。研究结果表明,透明溞为嫌盐种,对盐度耐受性低。透明溞可作为水产经济动物开口饵料、水体盐碱变化的指示生物,对水环境监测具有重要意义。

Effects of Salinity on Survival,Growth and Reproduction in Water Fleas Daphnia hylina (Crastacea: Cladocera)

In this paper, the effect of different salinities on survival, growth and reproduction of water fleas Daphnia hyalina was studied under the condition of constant (20±1)℃ using experimental ecology methods. The results showed that the semi-lethal and the safe concentrations of salinity on water fleas were 24 h LC 50 =4.16, 48 h LC 50 =2.67, and SC=0.36, respectively. Duration before reproduction and effective accumulated temperature were found to be increased with the increase in salinity;body length growth rate increased first and then decreased with the increase in salinity, and the lifespan and intrinsic rate of increase decreased with increasing salinity. This showed that salinity had a significant effect on water fleas survival, growth and reproduction ( P <0.05). Water fleas were narrow-salt species, and its tolerance to salinity was relatively low than the most of freshwater cladocera. Capillus length of the D. hyalina in 0.5 salinity group was significantly greater than that in control group. Therefore, it can be used as a bait for the development of aquatic economic organisms, and the indicator organisms for changes in saline-alkali water are of great significance for the monitoring of water environment.