不同藻密度下Cd2+浓度对萼花臂尾轮虫生命表统计学参数的影响

为了比较不同食物密度下污染物浓度对受试生物的慢性毒性，筛选出以轮虫为受试生物对水环境中Cd污染进行监测的敏感指标，研究了在不同斜生栅藻密度(1.0×10⁶、3.0×10⁶和5.0 ×10⁶ cells·ml^-1)下不同浓度(2.5、5.0、10.0、20.0和40.0 μg·L^-1)Cd²⁺对萼花臂尾轮虫生命表统计学参数的影响.结果表明：(25±1) ℃下Cd²⁺对轮虫的24 h LC₅₀为37.7 μg·L^-1.与各藻密度下的对照组相比，当藻密度为1.0×10⁶ cells·ml^-1时，20.0和40.0 μg·L^-1的Cd²⁺显著延长了轮虫的世代时间，5.0 μg·L^-1的Cd²⁺显著提高了轮虫的后代混交率；当藻密度为3.0×10⁶ cells·ml^-1时，除了5.0 μg·L^-1外，其他浓度的Cd²⁺显著降低了轮虫的后代混交率；而当藻密度为5.0×10⁶ cells·ml^-1时，Cd²⁺浓度对轮虫的所有生命表统计学参数均无显著影（P>0.05）.藻密度对轮虫的世代时间、生命期望、净生殖率和后代混交率均有显著影响（P<0.05），Cd²⁺浓度对轮虫的世代时间和后代混交率有显著影响（P<0.05），两者交互作用对后代混交率有极显著影响（P<0.01）.轮虫的世代时间和后代混交率是在1.0×10.6和3.0×10.6 cells·ml^-1食物密度下对Cd²⁺污染比较敏感的参数，其中后代混交率最敏感.

Effects of Cd2+concentration on life table demography ofBrachionus calyciflorus under differentScenedesmus obliquus density.

In order to understand the chronic toxicity of a pollutant to an organism in an aquatic environment with different food density, and screen out sensitive endpoints for monitoring Cd²⁺ pollution with rotifers as test animals, this paper studied the effects of different concentration (2.5, 5.0, 10.0, 20.0 and 40.0 μg·L^-1) Cd²⁺ on the life table demography of Bracionus calyciflorus at the Scenedesmus obliquus density being 1.0×10⁶, 3.0×10⁶, and 5.0×10⁶ cells·ml^-1. The results showed that at 25±1 ℃, the 24 h LC₅₀ of Cd²⁺to B. calyciflorus was 37.7 μg·L^-1. Compared with the controls at the same food density, when the S. obliquus density was 1.0×10⁶ cells·ml^-1, 20.0 and 40.0 μg·L^-1 of Cd²⁺prolonged the generation time of B. calyciflorus significantly, and 5.0 μg·L^-1of Cd²⁺ increased the percentage of B. calyciflorusmictic offspring. When the S. obliquus density was 3.0×10⁶ cells·ml^-1, the Cd²⁺at all test concentrations except 5.0 μg·L^-1 decreased the percentage of mictic offspring; when the S. obliquus density was 5.0×10⁶ cells·ml^-1, all test concentration Cd²⁺ had no effects on the life table demography (P>0.05). S. obliquus density had significant effects on the generation time, life expectancy at birth, net reproduction rate, percentage of mictic offspring of B. calyciflorus (P<0.05), Cd²⁺ concentration had significant effects on the generation timeand the percentage of mictic offspring (P<0.05), and the interaction of S. obliquus density and Cd²⁺ concentration had significant effects on the percentage of mictic offspring ( P<0.01). Among all the studied parameters, the generationtime and the percentage of mictic offspring were more sensitive to Cd²⁺ pollution under the algal densities of 1.0×10⁶ and 3.0 ×10⁶ cells·ml^-1, with the latter being the most sensitive.