Nature Environment and Pollution Technology

U. Srineetha ¹, M. Venkata Reddy ², M. Bhaskar ¹

Affiliations
1 Department of Zoology, Sri Venkateswara University, Tirupati-517 502, A. P., IN
2 Department of Zoology, Sri Krishnadevaraya University, Anantapuramu-515 055, A. P., IN

Abstract

The present study was aimed to investigate the total oxygen consumption of freshwater fish Cyprinus carpio during exposure and acclimation to sublethal acidic pH (5.0) medium. The oxygen consumption of fish significantly depleted in all the days of exposure to sublethal acidic pH 5.0 starting from first day to fourteen days of exposure. The rate of total oxygen consumption depletion was higher on first day. From the second day onwards a gradual decreasing trend was observed in the depletion up to 14th day of exposure. The unit oxygen consumption of fish on exposure to sub-lethal pH medium exhibited significant depletion when compared to control. The rate of depletion was maximum in the initial days of exposure and was reduced gradually in twelfth and fourteenth day of exposure. But, at day 14th not significant decrease was observed in both the parameters of the experimentation. This observation indicates that the fish was capable of regulating their metabolic modulations and physiological functions through acclimation process to be the possible reason for the successful survival of fish in acidifying water. The reduced oxygen consumption of fish on exposure to sublethal acidic medium confirms the prevalence of hypoxic condition in the surrounding medium.

Keywords

Acidic pH, Oxygen Consumption, Cyprinus carpio L.

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M. Haranadha Reddy ¹, M. Venkata Reddy ¹, K. Radhakrishnaiah ¹

Affiliations
1 Department of Zoology, Sri Krishnadevaraya University, Anantapur-515 055, A.P., IN

Abstract

Small (20±2 g) and large (40±2 g) size groups of the freshwater snail Pila globosa were exposed to different concentrations of nickel (mg/L), and 96 hr LC₅₀ through percent and probit mortality of the animals and also by Dragstead and Behren's method were determined. There was a linear relationship between the percent or probit mortality and the nickel concentration of both the size groups of snails. Thus, the percent and/or probit mortality increased with the increase in concentration of nickel. The percent mortality plotted against log concentration of nickel gave sigmoid curves, whereas the probit mortality plotted against log concentration gave straight lines in both the groups of snails. The 96 hr LC₅₀ obtained for small and large size groups of snails are 117.6 mg/L and 206.3 mg/L respectively. These values obviously indicated a significant (P<0.001) increase in the LC₅₀ of nickel with the increase in the size of the snail. The results of the present study indicate that the small size groups of snails are more sensitive to nickel than the large size groups.

Keywords

Pila globosa, Toxicity Evaluation, Nickel Toxicity, 96 hr LC₅₀.

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