长额象鼻溞对海水盐度的适应性

Adaptability of water fleas Bosmina longirostris to seawater salinity

在室内采用实验生态学方法，于（25±1）℃恒温条件下研究了不同盐度（0．1、0．5、1．0、1．5）对长额象鼻溢Bosmina longirostris生长、存活、繁殖和内禀增长率的影响。结果表明：长额象鼻涵是一种对盐度急变的耐受性极低和对盐度变化极为敏感的淡水枝角类，该溢24h LC50为4．62，生活的最适盐度为0．1—0．5，盐度仅在很低和微小增加时，才对其生活的某些方面有积极的影响；该潘的内禀增长率（rm）为0．241d^-1，低于其他种类，开发作为经济水产动物活饵料的潜力不大；从对盐度变化的敏感性来看，该涵有可能作为淡水污染、盐碱化等方面的监测生物，对环保、饮用水的生物监测具有重要意义。

Effect of salinity on survival, growth, reproduction and intrinsic rate of increase （ rm ） of water fleas Bosmina longirostris were studied in laboratory conditions by means of experimental ecological methods to evaluate adaptability of freshwater cladocerons to marine salinity. The water fleas collected from Biliuhe Reservoir with the salinity about 0.1 were exposed to different salinity （0.1,0.5, 1.0, and 1.5） at （25 ± 1 ） ℃. The results showed that the LC50 of salinity was found to be 4.62 in 24 h for the water fleas and optimal salinity to be from 0.1 to 0.5. Within the salinity from 0.1 to 0.5, the number of young per brood, the number of young per female, the number of broods per female, lifespan, days between broods and intrinsic rate of increase （ rm） were dropped with increase in salinity, but the age at first reproduction was shorter, indicating that Bosmina longirostris is a halophobe species in freshwater cladocerons with the lethal upper salinity of as low as 1 - 2 for natural distribution. This cladocera is unworthy as a new live animal food in larvae culture of marine fishes owing to low salinity adaptability and low intrinsic rate of increase.