Effect of Heavy Metals,Mercury and Copper,on Plasma Electrolytes in Freshwater Fish Cyprinus carpio var. communis

Abstract

In the present study the effect of heavy metals, mercury and copper, on plasma electrolytes viz., sodium, potassium and chloride have been investigated in economically important fish Cyprinus carpio var. communis. C. carpio were exposed to sub-lethal levels of mercury (0.03 ppm) and copper (0.096 ppm) under strict identical hydro-physiochemical conditions. Significant decline in these three electrolytes were observed when fish were exposed to sub-lethal levels of mercury chloride and copper sulphate during chase period of 7, 14, 21, 28 and 35 days.

The decrease in sodium ions was proportional to exposure time in mercury with maximum observed decrease of 33.0% on 35th day, whereas a maximum decrease of 66.36% was noted on 7th day in copper. Plasma potassium level of Cyprinus carpio var. communis declined continuously in the mercury treated fish showing a maximum per cent decrease of 54.68 at the end of the 28th day. The plasma chloride level observed a maximum decrease of 46.02% and 80% at the end of 7th day in the mercury and copper-treated fish respectively. The mercury-treated fish maintained the percent decrease of 22.56, 36.98, 38.08 and 39.02 on the 14, 21, 28 and 35th days. However, in the plasma chloride level in copper-treated fish a gradual recovery during subsequent exposure periods was observed giving a per cent decline of 61.23%, 45.39%, 34.02% and 10.11% at the end of the 14th, 21st, 28th, and 35th days, respectively. Hence, results indicated that pollutants including toxic heavy metals and useful micronutrient when a safe level exceed are reflected by the decrease in the plasma electrolytes of fish. The electrolyte levels in fish can be used for biomonitoring and Ecological Risk Assessment.