近亲裸腹溞对海水盐度的适应性

为了解淡水枝角类对海水盐度的适应性，在实验室内采用种群实验生态学方法研究25 ℃±0.5 ℃恒温条件下不同盐度（0、1、2、3、4、5）对近亲裸腹溞(Moina affinis)生存、生长和生殖的影响.结果表明，在各盐度梯度范围内，近亲裸腹溞的平均寿命随盐度升高而缩短，盐度4和5组内禀增长率与其它各组差异显著；盐度4和5组平均每窝产幼量与对照及其他组差异显著.一生产幼量除盐度1组和对照组较高外，其他各组均显著下降.对照组体长增长幅度与日增长率均低于各处理组.日增长率随着盐度的升高而增大.个体平均每胎产幼量以盐度1、2组最高.盐度5为近亲裸腹溞的生存和生殖盐限，但经过短期的海水驯化，其生殖耐盐上限有所提升，可达6.5.

Adaptability of Moina affinis (Crustacea: Cladocera: Moinidae) to seawater salinity

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 degrees C +/- 0.5 degrees C 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 (rm) 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.