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.

Keywords:

• East Calcutta Wetlands
• zooplankton
• oxidative stress
• antioxidants
• biomarker
• cladocera
• copepoda

Acknowledgments

Authors thankfully acknowledge the All India Council for Technical Education (AICTE) for laboratory infrastructure and the University Grant Commission (UGC) for financial support for the project work. Authors are also thankful to the Director of Technical Education and the Director of Public Instructions, Govt. of West Bengal, India for cooperation and necessary infrastructural support. Authors also express their thanks to Dr. Anjan Biswas for providing laboratory facilities and Ms. Sucharita Samaddar for her efforts during field surveys and laboratory analysis.