East Kolkata Wetlands


The East Calcutta Wetlands,, are a complex of natural and human-made wetlands lying east of the city of Calcutta, of West Bengal in India. The wetlands cover 125 square kilometres and include salt marshes, as well as agricultural fields, sewage farms and settling ponds. The wetlands are also used to treat Kolkata's sewage, and the nutrients contained in the wastewater sustain fish farms and agriculture.
The name East Calcutta Wetlands was coined by Dhrubajyoti Ghosh, Special Advisory, Commission on Ecosystem Management, IUCN, who reached this incredible but neglected part of the city when, while working as an engineer for the Government of West Bengal's Water & Sanitation Department, he was searching for an answer to the question: What exactly happens to the city sewage? These natural water bodies which were known just as fisheries provided the answer. Devised by local fishermen and farmers, these wetlands served, in effect, as the natural sewage treatment plant for the city. The East Kolkata Wetlands host the largest sewage fed aquaculture in the world..

Protecting the East Kolkata Wetlands

In 1991 the West Bengal Government accepted an offer by a non-resident Indian to build a World Trade Centre and allotted 227 acres of wetlands for this purpose. As a result, the NGO People United for Better Living in Calcutta filed a public interest litigation in the Calcutta High Court arguing for the importance of the wetlands and why they should be left as they were. The of Justice Umesh Chandra Banerjee on this matter is considered a landmark judgment. Not only did it go into the definition of wetlands and a review of their status in countries such as Australia and the US, he also brought to bear his own research on their functional values and role in "maintaining micro-climatic conditions, absorbing pollution...habitat for aquatic flora fauna... providing a spill basin, and the fragility of the ecosystem." The outcome was that the proposal for the World Trade Centre was turned down in its original form and strict conditions were laid: "I do not find any justiciable reason to disagree with the opinion expressed by the environmentalists that wetland should be preserved and no interference or reclamation should be permitted."
Following the order of the Calcutta High Court in 1992,to its credit, the State Government did not appeal but accepted the ruling. In fact, the Environment Secretary, Kalyan Biswas, applied for the East Calcutta Wetlands to be designated a "wetland of international importance" under the Ramsar Convention. This was obtained in 2002. Finally, in 2006, as a reflection of state and civil society partnership, the East Kolkata Wetlands Act was passed - the first such case of a major environmental legislation being enacted by a state - as distinct from the central - government.
Over the years, these wetlands have faced continuing threats and encroachment. In many instances, the original petitioner, PUBLIC, has had to go to court to argue on the basis of the 1992 judgment and the later EKW Act to ward off project proposals that were in fact disguised attempts at land-grabbing. While minor encroachments continue even today, the East Kolkata Wetlands still survive.

Flora

There are about 100 plant species, which have been recorded in and around the East Calcutta Wetlands. These include
Sagittaria montividensis, cryptocoryne ciliata, Cyperus spp., crostichum aureum, Ipomoea Aquatica, etc. The Sunderbans used to extend up to patuli in the 1950s.
Several kinds of water hyacinths grow across these wetlands. Local farmers and fisher folk use water hyacinth to create a buffer between land and water to minimise erosion.
The area is also home to large numbers of coconut and betel nut trees. Many varieties of vegetables are farmed here, including cauliflower, eggplant, pumpkin, sunflower and sacred basil. Tracts of land are dedicated to paddy cultivation as well.

Fauna

Numerous species of fish are farmed in the sewage fed ponds called bheris in the East Kolkata wetlands. These include silver carp, tilapia,
The area is also home to marsh mongoose and small Indian mongoose. Palm Civet and Small Indian Civet are significant in and around East Calcutta Wetlands. Approximately 20 mammals are reported from this region. Snakes found in the East Calcutta Wetland include Checkered keel back, Smooth water snake, Buff striped keel back and Bronze back tree snake It is the Type locality of a mammalian species, called Salt Lake Marsh Mongoose. Over 40 species of birds can be spotted at the wetlands. The process of urbanisation however, is leading to the disappearance of many bird species from the area.

Sewage treatment

Kolkata is an example of how natural wetlands are sometimes being utilised in developing countries. Using the purification capacity of wetlands, the Indian city of Kolkata has pioneered a system of sewage disposal. Originally built to house one million people, Kolkata is now home to over 10 million people, with nearly one-third of them living in slums. But the 8,000-hectare East Kolkata Wetlands Ramsar Site, a patchwork of tree-fringed canals, vegetable plots, rice paddies and fish ponds – and the 20,000 people that work in them – daily transform one-third of the city's sewage and most of its domestic refuse into a rich harvest of fish and fresh vegetables. For example, the Mudially Fishermen's Cooperative Society is a collective of 300 families that lease 70 hectares into which wastewater from the city is released. Through a series of natural treatment processes – including the use of Eichhornia crassipes and other plants for absorbing oil, grease and heavy metals – the Cooperative has turned the area into a thriving fish farm and nature park.

Controversy

Recently illegal landfills are on the rise and the wetlands are being slowly assimilated in the stream city. This unprecedented land development and urbanisation are creating concerns about the impact on the environment.
Wetlands are under threat due to exponential expansion of real-estate projects in eastern Kolkata especially in the Salt Lake and Rajarhat sectors. Nowadays, land encroachment and land alteration are the important aspect of threats for East Kolkata Wetland. Transformation from wetland to fishing pond, i.e., aquaculture field are become a potential threat to EKW.

Microbial Biodiversity

Microbial Diversity is an integral part of biodiversity which includes bacteria, archaea, fungi, algae, protozoa and protists. East Kolkata Wetland shows an immense diversity of flora and fauna both at the macro and micro level. Microbial richness of a region is its unseen asset that needs to be explored and conserved. Soil samples collected from ECW shows the presence of various new strains of microbes which are not only ecologically important but also have commercial value. These include Actinobacteria which are responsible for the degradation of nitrophenol, nitroaromatic compounds, pesticides and herbicides; Proteobacteria related to the bioremediation of heavy metals, degradation and recycling of woody tissues of plants, oil contaminated soil and toxic compounds and nitrogen fixation along with the cyanobacters; other bacteria playing important roles in metal accumulation, oil degradation, antimicrobial compound production, enzyme production etc..

Role in climate change mitigation

Sewage fed aquaculture based artificial wetland, like East Kolkata Wetland, is a robust example of potential carbon sink and spin-off. EKW can sequester ~1.9 Mg C/ha/year, mitigating at least ~118 Gg atmospheric CO2/year. Plus, carbon uptake by harvested fish crop corresponds to ~61 Gg CO2/year - rewarding USD 3.6/kg blue C harvested.

Conservation and Management Act

The East Kolkata Wetlands Act, 2006 represents an important landmark as it paved way for establishment of the East Kolkata Wetlands Management Authority for conservation and management of the EKW. The EKWMA is constituted under Section 3 of the Act, 2006. In 2017 Section 3 of the Act, 2006 has been amended and the composition of the EKWMA has been changed. The EKWMA is a thirteen member body with the Chief Secretary, Government of West Bengal, Secretaries of different Departments of State Govt. as well as four experts nominated by the State Govt. under the chairmanship of Minister-in-Charge, Department of Environment, Government of West Bengal.
The EKWMA is guided by the East Kolkata Wetlands Act, 2006, the East Kolkata Wetlands Rules, 2006, and the Wetlands Rules, 2017.