Indian wetlands, ‘kidneys of Kolkata,’ face imminent threats


The vital wetlands located just outside the bustling Indian city of Kolkata are currently under severe threat. These wetlands have served as a crucial source of food and employment, as well as a natural sewage filtration system through fish ponds for generations. However, the rapid pace of urbanization is now endangering this delicate ecosystem, leading conservationists to sound the alarm.

Tapan Kumar Mondal, a 71-year-old fish farmer who has dedicated his life to working within the intricate network of canals and ponds spanning approximately 125 square kilometers (48 square miles), lamented the destructive impact of human activity. “We are destroying the environment,” he warned, highlighting the detrimental effects of an increasing population and the resulting pressure on nature.

Designated as a wetland of global significance under the United Nations Ramsar convention, these waters have played a vital role in the megacity of Kolkata. Apart from acting as a natural climate regulator by providing cooling effects in sweltering temperatures, they have served as crucial flood defenses for the low-lying city.

However, Dhruba Das Gupta from the environmental group SCOPE voiced concerns that short-sighted urban development is rapidly encroaching upon these wetlands, causing them to shrink. To address this urgent issue, Gupta is attempting to secure funding for a study to assess the current state of the wetlands and gauge the extent of the damage.

On a daily basis, an astounding 910 million liters of nutrient-rich sewage flow into the wetlands, nourishing approximately 250 ponds covered in hyacinths. “Sunlight and sewage create a massive plankton boom,” explained K. Balamurugan, chief environment officer for West Bengal state. The microorganisms thriving in the shallow fish ponds facilitate the rapid growth of carp and tilapia. After the fish have consumed their share, the water runoff is used to irrigate nearby rice paddies, while the remaining organic waste enriches vegetable fields.

Balamurugan affectionately refers to these wetlands as the “kidneys of Kolkata” because they naturally treat 60 percent of the city’s sewage, saving over $64 million annually, according to a study conducted by the University of Calcutta in 2017. Furthermore, the wetlands support agricultural activities that contribute 150 tonnes of vegetables and 10,500 tonnes of fish each year, providing employment opportunities for tens of thousands of people.

Beyond their environmental and economic significance, the wetlands also serve as a crucial defense against flooding for Kolkata, a city vulnerable to rising sea levels caused by climate change. Balamurugan emphasized their role as a natural sponge, effectively absorbing excess rainwater and preventing flooding.

Dhruba Das Gupta stressed the wetlands’ invaluable contribution to biodiversity and climate stabilization. Labeling them as the “lifeline of Kolkata,” she asserted that their preservation is paramount due to the cooling effect they bring about merely by their presence.

However, the Ramsar listing underscores the growing concern that industrial effluents are contaminating these natural systems, thus endangering food production. Sujit Mondal, a fish farmer, expressed his worry about reduced production compared to the previous year, attributing it to the murky water resulting from pollution.

A staggering 95 percent of the wetlands are privately owned, making them vulnerable to encroachment driven by escalating land prices. Environmental officials have pleaded with landowners to refrain from filling in the fish ponds for construction purposes. Balamurugan emphasized their appeal, stating, “We asked them not to convert or trade these wetlands for buildings, not to get them filled.”

Regrettably, residents claim that village councils are being enticed by developers hungry for land. Allegations of informal permissions being granted in exchange for financial incentives have raised concerns. Das Gupta warned that such practices lead to the loss of productive spaces and the destruction of the vital ecosystem services provided by these wetlands.

“The land is being snatched from people,” lamented Sujit Mondal, who has witnessed firsthand the pressure exerted on fishermen to abandon their livelihoods. Criminal groups have even resorted to illegally netting the ponds at night, stealing the fish and leaving farmers with little choice but to close down and sell their properties.

Das Gupta concluded by urging immediate action to safeguard the wetlands, which face the imminent risk of irreversible damage. The fate of this ecological treasure hangs in the balance as the fight to protect it intensifies against the backdrop of rapid urban expansion and illicit land grabs.

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