摘要
Heavy metal pollution is widespread in some areas of China and results in contamination of land, water, and air with which all living organisms interact. In this study, we used three heavy metallic ions （Cu^2＋, Pb^2＋ and Zn^2＋） to assess their toxicity effects on mortality, blood biomarker and growth traits （body length and body mass） of Rana zhenhaiensis tadpoles. The results showed that the toxicity levels of the three metallic ions were different when conducted with different experiment designs. For acute toxicity tests, Cu^2＋ was the most toxic with the highest tadpole mortality. The mortalities of tadpoles showed significant differences among the treatments at the same exposure time endpoints （24, 48, 72 and 96h）. Results from repeated measures ANOVA indicated that metallic ion concentration, exposure time and their interactions significantly affected the mortalities of R. zhenhaiensis tadpoles. Also, the toxicity effects of all binary combinations of the three metallic ion treatments showed synergism. The half lethal concentrations （LCs0） decreased with increasing exposure time during the experimental period, and the safe concentration （SC）values of Cu^2＋, Pb^2＋ and Zn^2＋ were different from each other. Combined and compared LC50 values with previous data reported, it is suggestes that the toxicity levels of metal pollution to anuran tadpoles should be species-and age-related. For blood biomarker tests, Zn^2＋ was the most toxic with the highest total frequencies of abnormal erythrocytic nucleus. All three metallic ions caused higher abnormal erythrocytic nucleus compared with control groups. In a chronic toxicity test, Pb^2＋ was the most toxic with lowest growth traits. Survival rate （except for 18 days）, total body length and body mass showed significant differences among the treatments. These findings indicated that tadpoles of R. zhenhaiensis should be as a bioindicator of heavy metals pollution.
Heavy metal pollution is widespread in some areas of China and results in contamination of land, water, and air with which all living organisms interact. In this study, we used three heavy metallic ions （Cu^2＋, Pb^2＋ and Zn^2＋） to assess their toxicity effects on mortality, blood biomarker and growth traits （body length and body mass） of Rana zhenhaiensis tadpoles. The results showed that the toxicity levels of the three metallic ions were different when conducted with different experiment designs. For acute toxicity tests, Cu^2＋ was the most toxic with the highest tadpole mortality. The mortalities of tadpoles showed significant differences among the treatments at the same exposure time endpoints （24, 48, 72 and 96h）. Results from repeated measures ANOVA indicated that metallic ion concentration, exposure time and their interactions significantly affected the mortalities of R. zhenhaiensis tadpoles. Also, the toxicity effects of all binary combinations of the three metallic ion treatments showed synergism. The half lethal concentrations （LCs0） decreased with increasing exposure time during the experimental period, and the safe concentration （SC）values of Cu^2＋, Pb^2＋ and Zn^2＋ were different from each other. Combined and compared LC50 values with previous data reported, it is suggestes that the toxicity levels of metal pollution to anuran tadpoles should be species-and age-related. For blood biomarker tests, Zn^2＋ was the most toxic with the highest total frequencies of abnormal erythrocytic nucleus. All three metallic ions caused higher abnormal erythrocytic nucleus compared with control groups. In a chronic toxicity test, Pb^2＋ was the most toxic with lowest growth traits. Survival rate （except for 18 days）, total body length and body mass showed significant differences among the treatments. These findings indicated that tadpoles of R. zhenhaiensis should be as a bioindicator of heavy metals pollution.
基金
funded by the National Natural Science Foundation of China(31270443)
Natural Science Foundation of Zhejiang Province(LY13C030004)
