Cd^2＋对角突臂尾轮虫和曲腿龟甲轮虫的急性毒性和生命表统计学参数的影响

Acute toxicityand effect of Cd^(2+) on life table demography of Brachionus angularis and Keratella valga

采用急性毒性试验研究了(25±1)℃下Cd2+对角突臂尾轮虫(Brachionus angularis)和曲腿龟甲轮虫(Keratella valga)的24 hLC50值,采用生命表实验方法研究了(25±1)℃下、以密度为1.0×106个细胞/mL的斜生栅藻为轮虫食物时不同浓度(7.0、12.0、20.4、34.6、58.8、100.0μg/L)的Cd2+对角突臂尾轮虫和曲腿龟甲轮虫生命表统计学参数的影响。结果表明,Cd2+对角突臂尾轮虫和曲腿龟甲轮虫幼体的24 hLC50值分别为95.5μg/L和231.9μg/L。Cd2+浓度对角突臂尾轮虫的种群内禀增长率具有显著的影响(P<0.05),对曲腿龟甲轮虫的世代时间、生命期望和净生殖率具有显著的影响(P<0.05)。与对照组相比,100.0μg/L的Cd2+显著降低了角突臂尾轮虫的种群内禀增长率;34.6μg/L和58.8μg/L的Cd2+显著降低了曲腿龟甲轮虫的世代时间,34.6和100.0μg/L的Cd2+显著降低了曲腿龟甲轮虫的生命期望,34.6μg/L的Cd2+显著降低了曲腿龟甲轮虫的净生殖率。角突臂尾轮虫对Cd2+污染的敏感性较曲腿龟甲轮虫强,各生命表统计学参数对污染物的敏感性因轮虫种类的不同而异。

The 24 h LC50 values of Cd2＋ to Brachionus angularis and Keratella valga at（25±1）℃ were determined by acute toxicity tests,and the effects of Cd2＋ concentrations（7.0,12.0,20.4,34.6,58.8 and 100.0 μg/L） on the life table demographic parameters including survivorship,fecundity,life expectancy at hatching,generation time,net reproductive rate,intrinsic rate of population increase and proportion of mictic offspring of B.angularis and K.valga both cultured at（25±1）℃ and with 1.0×106 cells/mL of Scenedesmus obliquus as the rotifers′ food were studied by life table experiments.The results showed that the 24 h LC50 values of Cd2＋ to B.angularis and K.Valga were 95.5 and 231.9 μg/L,respectively.Cd2＋ concentration significantly affected the survivorships of B.angularis and K.valga（P0.05）.Compared with the controls,Cd2＋ at 100.0 μg/L decreased the survivorship of B.angularis,Cd2＋ at 34.6 and 100.0 μg/L decreased the survivorship of K.valga.The survivorships of K.valga were higher than those of B.angularis,when they were exposed to Cd2＋ at 0,7.0,20.4,34.6,58.8 and 100.0 μg/L（P0.05）.Cd2＋ concentration markedly affected the fecundity of B.angularis（P0.01）,but the fecundities of the rotifers exposed to all the concentrations of Cd2＋ were similar to that in the control.Cd2＋ concentration did not affect the fecundity of K.valga（P0.05）.When the concentrations of Cd2＋ were 12.0 and 100.0 μg/L,the fecundities of B.angularis were higher than those of K.valga.Cd2＋ concentration significantly affected the intrinsic rate of population increase of B.angularis,and generation time,life expectancy at hatching and net reproductive rate of K.valga（P0.05）.Compared with the controls,Cd2＋ at 100.0 μg/L significantly decreased the intrinsic rate of population increase of B.angularis.Cd2＋ at 34.6 and 58.8 μg/L shortened the generation time,Cd2＋ at 34.6 and 100.0 μg/L shortened the life expectancy at hatching,and Cd2＋ at 34.6 μg/L decreased the net reproductive rate of K.valga.B.angularis is more sensitive to Cd2＋ pollution than K.valga.The sensitivity of life-table demographic parameters to Cd2＋ pollution depends on the test rotifer species.The relationship between the generation time（Y,h） of B.angularis and Cd2＋ concentration（X,μg/L） could be described by Y=-0.011X2＋0.657X＋71.719（R2=0.570,P0.01）.