TOXICOLOGICAL EFFECTS OF A BINARY MIXTURE OF METALS (Fe+Mn) ON THE OXIDATIVE STRESS OF MAJOR CARPS

Abstract

Oxidative stress caused by various pollutants in water can be overcome by different mechanisms in aquatic organisms. Antioxidant enzymes play major role to minimize the hazardous effect of heavy metals in fish. Superoxide dismutase is one of the antioxidant enzyme that converts the superoxide radical into hydrogen peroxide (H2O2) and thus minimize the stress caused by free radicals. Therefore, the aim of this research was to evaluate the activity of superoxide dismutase (SOD) in the organs (liver, kidney, gills and muscles) of Catla catla and Cirrhina mrigala exposed to 1/3rd and 1/4th concentrations of 96-hr LC50 of Fe+Mn. These experiments were conducted in glass aquaria with three replications of each concentration for 1 month in controlled laboratory conditions. SOD activity was significantly increased in liver and gills of both fish species compared to control group. Maximum SOD activity in the Fe+Mn mixture exposed Catla catla was measured as 46.55±7.58 and 43.69±5.34 UmL-1 in the liver and gills, respectively, at 1/4th concentration of 96-hr LC50 while in control fish the activity of SOD was recorded as 33.36±6.72 and 34.16±3.19 UmL-1, respectively. Similarly, SOD activity increased with decrease in concentration in Cirrhina mrigala. Maximum activity of enzyme (52.30±7.33 UmL-1) in Cirrhina mrigala was observed in the liver at 1/4th concentration of 96-hr LC50 compared to control in which the activity of enzyme was recorded as 46.95±3.93 UmL-1. The SOD activity in all the metals mixture treated and un-treated fish groups were found lower in muscles than that of other organs.