Abstract

An attempt has been made in the present investigation to determine the acute toxicity of hexavalent chromium and its toxicological effects on survival, physiological, hematological and biochemical parameters of the widely consumed Indian major carp, Labeo rohita. Short-term acute toxicity tests were performed adopting renewal bioassay technique (USEPA, 1975) over a period of 96 h, using different concentrations of potassium dichromate to the fish and the 96 h LC[50] value was found to be 111.45 mg/l (Cr(+6) as 39.40 mg/l). ANOVA results showed that the normal respiratory activity of the fish was significantly affected and there is a depression in the metabolic rate at the end of 24, 48, 72 and 96 h exposure. The metal also induced significant decrease (p<0.001) in the hematological parameters of the fish like total erythrocyte count, hemoglobin percent and absolute value Mean cell hemoglobin (MCH) both at the end of 24h and 96 h exposure indicating anemia. Appreciable decline in the biochemical profiles such as total glycogen, total lipids and total protein contents of the fish was also observed. However, the decrease in protein content was significant only at the end of 96 h. This study reflects the extent of the toxic effects of hexavalent chromium and the metal induced cumulative deleterious effects at various functional levels in the widely consumed freshwater fish, Labeo rohita.

Highlights

  • Freshwaters are highly vulnerable to pollution since they act as immediate sinks for the consequences of human activity always associated with the danger of accidental discharges or criminal negligence

  • Labeo rohita were obtained from the Government Fish Farm at Nidubrolu town (160.5’N; 800.5’ E) and healthy fish were acclimated in the laboratory for 15 days in plastic pools of 100 litres capacity containing well-aerated unchlorinated groundwater before they were used for experiments

  • Behavioural manifestations of acute toxicity like copious secretion of mucus, loss of scales, discoloration, surfacing and darting movements were observed in Labeo rohita exposed to higher concentrations of potassium dichromate viz., 120 mg/l, 140 mg/l and 150 mg/l from 48 h to 96 h

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Summary

Introduction

Freshwaters are highly vulnerable to pollution since they act as immediate sinks for the consequences of human activity always associated with the danger of accidental discharges or criminal negligence. Heavy metals constitute a core group of aquatic pollutants and additional concentrations of these metals accumulate in the aquatic ecosystems as a result of land-based activities [1]. Fish mostly have a tendency to bio-accumulate heavy metals and humans can be at great risk sometimes even lethal, through contamination of the food chain [2]. Chromium continues to be in widespread use in industry, paints, metal plating as corrosion inhibitor and its particulates enter the aquatic medium through effluents discharged from tanneries, textiles, electroplating, mining, dyeing, and printing industries, photographic and pharmaceutical industries. Chromium is a compound of biological interest, probably having a role in glucose and lipid metabolism as an essential nutrient [3]

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