Author(s): Shunmugam Subbiah, Mathan Ramesh, Anila P Ashokan and Arul Narayanasamy

Abstract: Tebuconazole (TCZ), an azole fungicide has been commonly used in a variety of industry and agriculture products. TCZ is persistent in the environment and thereby posing a risk to aquatic organisms. The present study is aimed to investigate the acute and sublethal toxicity of TCZ on ionic regulation and Na⁺/K⁺-ATPase activity in a freshwater fish Cirrhinus mrigala. The median lethal concentration of TCZ for 24 and 96 h (with 95% confidence limits) were found to be 9.6 and 7.2 mg L^-1, respectively. For sublethal toxicity study, 1/10th of 24 h LC₅₀ value (0.96 mg L^-1) and 1/5th of 96 h LC₅₀ value (1.44 mg L^-1) were taken. In acute treatment, plasma sodium and potassium levels were found to be decreased significantly (p<0.01) in TCZ treated fish whereas a significant increase in plasma chloride level and gill Na⁺/K⁺-ATPase activity was observed. In sublethal treatment, plasma sodium level was found to be increased up to 7^th day in both the concentrations. After 7^th day, plasma sodium level exhibited a significant decrease when compared to control group. Plasma potassium level was found to be decreased in both the concentrations throughout the exposure period when compared to control group (p < 0.05). Significant increase in plasma chloride level was observed in fish exposed at 0.96 mg L^-1 for a period of 35 days. However, at 1.44 mg L^-1 concentration, a fluctuation of plasma chloride level was observed. Gill Na⁺/K⁺-ATPase activities were found to be increased throughout the study period in both the concentrations. The findings of the present study indicate that TCZ can change the Na⁺/K⁺-ATPase activity which in turn alter the plasma electrolyte levels. The alterations of these parameters can be used for monitoring of azole fungicides in the aquatic environment.

Pages: 361-371  |  916 Views  267 Downloads

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