Adaptability of water fleas Bosmina longirostris to seawater salinity
WEI Jie, ZHAO Wen, YANG Wei-dong, YANG Dan-guang, LI Sheng-hong
1. Key laboratory of Hydrobiology in Liaoning Province＇s University, Dalian Fisheries Univ. , Dalian 116023, China; 2. Laohutan Marine Park of Dalian, Dalian 116000, China
Abstract: 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.
2009, Vol. 24 
