Ecosystem service assessment of selected wetlands of Kolkata and the Indian Gangetic Delta: multi-beneficial systems under differentiated management stress

Mark Everard,Harry Dixon,Ritesh Kumar,Priya Joshi,Rajiv Kangabam,Lalu Das,Dhaval Joshi,Manoj Kumar Tiwari,Richard Allan,Gautam Hirak Talukdar,Rob Mcinnes

doi:10.1007/s11273-019-09668-1

Abstract

A structured literature review using the search term ‘ecosystem services’ found few relevant studies relating to three contrasting wetlands in West Bengal: the unpopulated Sudhanyakhali Island in the Sundarbans National Park, the populated Gosaba Island separated from Sudhanyakhali Island by a narrow channel, and the East Kolkata Wetland (EKW). Subsequent structured review focused on the EKW using specific service-related terms located only 2 provisioning, 6 regulating, 1 cultural and 3 supporting services. Few services are currently recognized in the literature, with significant gaps in whole service categories. Significantly, there was no published evidence of a systemic overview of service production at these sites. Field observations and stakeholder dialogue informed assessment of ecosystem services using the Rapid Assessment of Wetland Ecosystem Services (RAWES) approach, adopted by the Ramsar Commission, on both islands and three discretely different areas of the EKW. The RAWES surveys found that 32 of 36 ecosystem services were produced from at least one assessed wetland site. Despite low sample size, statistically significant differences were observed in the range of services produced between the five wetland sites and the geographical range at which benefits accrued, explained by differing wetland characteristics and management regimes. Were decisions based solely on evidence provided by existing published knowledge, few ecosystem services would be considered and, potentially, whole ecosystem service categories might be overlooked. Importantly, there would also be no systemic account of service production and interdependencies. RAWES assessment serves as a practical, rapid and systemic approach, taking account of interdependent ecosystem services, supporting protection of the ecological character and achievement of wise use of wetlands. RAWES can also help redress perceptions that the values of peri-urban wetlands are currently under-represented.

Highlights

Wetland systems provide a diversity of beneficial ecosystem services for society
We review the ecosystem services provided by a small subset of wetlands in the outer Indian Sundarbans islands and different zones of the East Kolkata Wetlands (EKW) to the east of Kolkata city
Two principal wetland areas of differing character were selected for study of their ecosystem services: an unpopulated outer Sundarbans island within the World Heritage Site and Tiger Reserve (Sudhanyakhali Island); a populated outer Sundarbans island adjacent to the protected island (Gosaba Island); and the East Kolkata Wetland, in which three differing zones were selected for further study (Fig. 1)

Summary

Introduction

Wetland systems provide a diversity of beneficial ecosystem services for society. Human uses inevitably affect natural character and service production —attributes germane to Wise Use guidance under the intergovernmental 1971 Ramsar Convention on wetlands of international importance In the Bangladeshi region of the Sundarbans, potential decline in wetland ecosystem services such as provision of food and raw materials due to sea level rise are projected to drive losses of US$ 0–1 million to US$ 16.5–20 million under different scenarios (Mehvar et al 2019). Comparison of ecosystem services addressed in the literature with field assessments tests the value and utility of RAWES, and provides insights that may inform future wetland management and wise use challenges

Methods

Results

‘Literature’

Discussion

Conclusions