[Combined toxicity of copper and cadmium to cladoceran Moina marocopa]

In this paper, the 48 h LC50 values of Cu2+, Cd2+ and CU(2+)+Cd2+ (CU2+:Cd2+ = 1:1) to Moina macrocopa were determined by acute toxicity tests, and the effects of different concentrations of Cu2+, Cd2+ and Cu(2+)+Cd2+ on the life table demography of M. macrocopa were studied by life table demography. The 48 h LC50 of Cu2+, Cd2+ and Cu(2+)+Cd2+ to M. macrocopa was 0.106, 0.117 and 0.212 mg x L(-1), respectively, and the acute toxicity of Cu(2+)+Cd2+ mixture to M. macrocopa showed an antagonistic effect. Cu2+ had no significant effects on the life expectancy at hatching, gross reproductive rate, net reproductive rate, generation time, and intrinsic rate of population increase of M. macrocopa, whereas Cd2+ and Cu(2+)+Cd2+ had significant effects on the life expectancy at hatching, gross reproductive rate, net reproductive rate and generation time, but no significant effects on the intrinsic rate of population increase of M. macrocopa. Compared with the control, the 0.004 and 0.005 mg x L(-1) of Cd2+ and the 0.006-0.010 mg x L(-1) of Cu(2+)+Cd2+ decreased the life expectancy at hatching and the gross reproductive rate of M. macrocopa significantly, and the 0.004 and 0.005 mg x L(-1) of Cd2+ and the 0.008-0.010 mg x L(-1) of Cu(2+)+Cd2+ reduced the net reproductive rate and the generation time of M. macrocopa significantly. The chronic toxicity of Cu(2+)+Cd2+ mixture to M. macrocopa showed a synergistic effect. There existed significant dose-effect relationships between the concentrations of Cd2+ and Cu(2+)+Cd2+ and the life expectancy at hatching, gross reproductive rate, net reproductive rate, and generation time of M. macrocopa.