Abstract: By the methods of experimental ecology, this paper studied the effects of different salinity (0, 1, 2, 3, 4, 5) on the survival, growth, and reproduction of Moina affinis (Crustacea: Cladocera: Moinidae) at 25 ℃±0.5 ℃ under laboratory conditions, aimed to know the adaptability of freshwater cladocerans to seawater salinity. The results indicated that when the salinity increased from 0 to 5, the mean lifespan of M. affinis was 16.8±1.3, 17.8±3.5, 14.2±5.7, 13.0±1.6, 9.6 ±1.5 and 6.6±1.8 days, intrinsic increase rate (r_m) was 0.91±0.01, 0.96±0.01, 0.86±0.10, 0.86±0.05, 0.49±0.18 and 0.24±0.06 d^-1, mean eggs production per clutch was 34.5±3.7, 34.2±3.9, 27.5±7.1, 34.6±3.9, 12.3±5.0 and 9.1±2.1 ind., and life fecundity was 410±32, 445±84, 250±106, 294 ±47, 59±38 and 24±6 ind., respectively. There was a significant difference in mean lifespan, intrinsic increase rate, and mean eggs production per clutch between treatments salinity 0, 1, 2 and 3 and treatments salinity 4 and 5, and in life fecundity between treatments salinity 0 and 1 and treatments salinity 2, 3, 4 and 5. The body length and daily growth rate was lower in control than in other treatments. It was suggested that salinity 5 was the maximum threshold salinity for the survival and reproduction of M. affinis, but after a short period of acclimatization in diluted seawater, the maximum threshold could reach 6.5.

Key words: Landscape change, Heihe River Basin, Landscape metrics, GIS, FRAGSTATS