Abstract
Aquatic environments are often contaminated with zinc. Amphibian tadpoles are likely to be exposed to high concentrations of zinc present in these environments. We determined the acute and sub-chronic toxicity of ZnCl2 on Fejervarya limnocharis tadpoles under laboratory conditions. The LC50 values of ZnCl2 were found to be 5.81, 4.32, 3.79 and 3.61 mg/L at 24, 48, 72 and 96 h of exposure respectively. Long-term exposure to sub-lethal concentrations of ZnCl2 induced significant mortality in concentration and time dependent manner. Sub-lethal ZnCl2 exposure significantly altered survival, body length and body weight at metamorphosis. Micronucleus test and comet assay indicated the genotoxic potential of ZnCl2. Significant increase in DNA strand break was observed following ZnCl2 exposure equivalent to 1% of the of 24 h LC50 value. The findings indicate possible adverse to tadpoles inhabiting aquatic environments contaminated with zinc. In addition, the findings may be extrapolated to aquatic organisms of similar torphic status.
Highlights
Heavy metal contamination of aquatic environment is one of the common and persistent forms of pollution
Zinc is widely used in industry for manufacture of a broad range of products ranging from paints to pharmaceuticals and cosmetics
We have examined the effects of zinc on the tadpoles of F. limnocharis
Summary
Heavy metal contamination of aquatic environment is one of the common and persistent forms of pollution. Aquatic environments are polluted by heavy metals due to natural processes through weathering and leaching of mineral deposits (Purushothaman & Chakrapani, 2007; Adamu et al, 2015; Skordas et al, 2015) as well as human economic activities (Mohiuddin et al, 2011; Wei & Yang, 2010). Other common uses of zinc for economic activities include metal plating, plastic production, electrical components and battery manufacturing. Concentrations up to 4 mg/liter in water and 100 mg/kg dry weight in sediments have been reported in anthropogenically contaminated freshwater habitats (World Health Organization [WHO], 2001; Mondal et al, 2017; Sarkar et al, 2017). There are studies, though limited in number, suggesting that aquatic organisms exposed to higher concentrations of zinc could exhibit significant adverse
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