Adaptive co-management model for the East Kolkata wetlands: A sustainable solution to manage the rapid ecological transformation of a peri-urban landscape

Abstract Human-induced land use changes like agriculture and urban development occur commonly at the cost of natural wetlands, which require immediate attention and sustained efforts from urban planners and concerned governments. In view of the East Kolkata Wetlands (EKW), India, this paper has examined the trend, causes, extent and impacts of landscape transformation during the last few decades. This ‘ Ramsar siteof International Importance’ is one of the world's largest wastewater-fed aquaculture systems where the city sewage is recycled for pisciculture and agriculture, and acts as flood resistance for the city of Kolkata. Rapid encroachment in the EKW due to unplanned development has caused various environmental, social and economic impacts. The key ecological impacts found in the study included loss of faunal and floral diversity, eco-toxicological impacts, etc. In terms of biodiversity loss, while the number of bird species in the EKW decreased from 248 in 1960s to 72 in 2005, about 59% fish species are near threats, vulnerable and endangered. Persistent organic pollutants(POPs) in the EKW were found to have eco-toxicological impacts on human health by way of impacting the edible fish species. Open burning of dumped waste in Dhapa is found to be a potential source of polychlorinated biphenyls (PCBs), polychlorinated dibenzo dioxin/furans (PCDD/Fs) and organochlorine pesticides (OCPs), which were detected in human milk samples suggesting that Dhapa residents in the EKW are widely exposed to these contaminants. Soil samples from Dhapa dumping ground revealed maximum Ʃ26PCBs concentration of 21 ng/g, where open burning was prevalent. The ecological transformation of the EKW focussing on policy development and regulatory compliance issues has been studied in this paper. The aspects of encroachment and wetland shrinkage triggered by economic drivers like urban sprawlhave been analyzed. The paper presents adaptive co-management as the future roadmap for action to curb further degradation of the wetlands, and adopt an integrated approach of environmental, political, physical, economic and institutional aspects. It is envisaged that the adaptive co-management model will contribute to long-term sustainable sustenanceof the precious ecosystem.