Toxicidade do sulfato de zinco para girinos de rã-touro (Lithobates catesbeianus): Toxicidade aguda, crônica e parâmetros hematológicos

Abstract

The aim of this study was to evaluate the effect of zinc sulfate (ZnSO 4) on hematological parameters of bullfrog tadpoles, Lithobates catesbeianus through acute toxicity tests and chronic. Although the toxicity of zinc for several species of fish have been studied, the toxicity of this metal is not well known to all aquatic organisms, especially for amphibians. The action of this metal ion on the respiratory system of fish occurs by precipitation of the secretion of mucus produced by the gills of fish that die from asphyxiation. The acute toxicity tests showed that LC 50-96h (median lethal concentration) of zinc sulfate was 2.78 mg L-1 level below that set by CONAMA. Chronic toxicity tests were performed on three concentrations: CL 50-96h/100 (0.0278 mg L ZnSO 4 -1), LC 50-96h/10 (0.278 mg L ZnSO 4 -1) and LC 50-96h (2.78 mg ZnSO 4 L- 1) during 312 hours under semi-static, and a control group (without addition of zinc sulfate). Analyses of hematological parameters indicate the occurrence of changes, indicating the possibility of occurrence of chronic effects in tadpoles of L. catesbeianus, which should be better studied.