Antioxidant response to oxidative stress in zooplankton thrived in wastewater-fed ponds in East Calcutta Wetland Ecosystem, a Ramsar site

Abstract

The municipal sewage of Calcutta city together with industrial effluents traversed the East Calcutta Wetlands (ECW) (Ramsar Site No. 1208) for nearly a century. The composite wastewater at the ECW, was used for pisciculture and agriculture after natural stabilization. Such uses have always been thought to be a source of contamination to biota and humans. Some water-borne pollutants generate reactive oxygen species including superoxide radical anion (O2−.), hydrogen peroxide (H2O2), and hydroxyl radical (.OH), which are highly reactive and potentially deleterious to biological systems. The present study was initiated to examine the antioxidant activities against oxidative stress during different seasons in body fluids of two zooplankters, Moina micrura and Mesocyclops leuckarti thriving in wastewater-fed ponds of ECW. Results showed significantly higher electrical conductivity, chloride and metal (Cr, Cu, and Pb) concentrations in contaminated wastewater-fed pond (CP) at ECW compared to the uncontaminated village pond (UP). Zooplanktons thriving in CP displayed significantly higher superoxide dismutase and catalase activities at all seasons compared to those in UP. Seasonal variations in antioxidant activities were found to be in agreement with variations in limnochemical factors. Hence, antioxidant activity was used as a biomarker against oxidative damage in plankters surviving under pollutant stress.