Bengal’s Sunderbans billed ‘endangered ecosystem’, mangroves show signs of climate-resilience

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The Sunderbans in West Bengal – a UNESCO world heritage site and home to the only tiger that lives in mangroves – has been categorized as an ‘endangered ecosystem’ by a team of scientists from four countries.

But there is a silver lining too. The researchers have found that the world’s largest mangrove system, which has been degraded because of unbridled human activities in the past, is showing signs of stabilization and is gradually becoming resilient to climate change.

“The Sunderbans, which has seen much degradation in the past, has been categorized as an endangered ecosystem according to the International Union for Conservation of Nature’s The Red List of Ecosystems. Felling of trees for human settlement over the past few centuries which has degraded the mangrove to a large extent and the declining fish population were the two primary reasons to tag the delta as an endangered one. Ongoing threats, including climate change and reduced freshwater supply may further impact the delta,” said Punyasloke Bhadury, who heads the Centre for Climate and Environmental Studies at the Indian Institute of Science Education and Research.

The IUCN’s Red List of Ecosystems (RLE) is a global standard for assessing the risk of ecosystem collapse. The Giant Kelp Forest in Alaska, the tidal flats of Yellow Sea in east Asia and Lake Burullus in Egypt also fall in the endangered category. The Gnarled Mossy Cloud Forest in Australia and Gonakier forest in Senegal are two critically endangered ecosystems. The Aral Sea which has dried up has been tagged as a collapsed ecosystem.

“However, mangrove extent has since stabilised, tiger numbers are slowly recovering and analysis of mangrove condition highlights that only a small proportion of the forest is classified as degraded. We are cautiously optimistic about the future of the Indian Sundarbans,” said Michael Sievers, a scientist with School of Environment and Science at Griffith University in Australia and the corresponding author of the research paper.

The study was done by researchers from various institutes including the Oxford University and Griffith University in four countries – India, UK, Australia and Singapore. The findings have been published in the latest issue of Biological Conservation– a journal of the Elsevier group.

The Sunderbans sprawls over 10,200 sq km. While 4200 sq km lies in West Bengal in India, the remaining 6000 sq km is in Bangladesh. Around 200 tigers have adapted to this mangrove and hence have acquired global importance.

The scientists have analysed data of past five decades till March 2020, which means even though they have included the effects of Cyclone Aila in 2009 and Cyclone Bulbul in November 2019, they missed out the devastation caused by Cyclone Amphan in May 2020. Cyclone Amphan had devastated almost one third of mangrove forest, top forest officials had said.

The scientists have warned that despite the positive signs, several threats remain. Impacts from hydrological modifications and salinity alterations, from climate change and sea level rise, and from coastal erosion and reduced sediment supply all need to be properly monitored and managed where possible.

The findings have been shared with authorities of the state pollution control board and the forest department.

“We are planting around 50 million saplings of mangrove species in the Sunderbans to cope with the loss which the delta has suffered during Cyclone Amphan. The tiger population has increased from 88 to 96 in the past one year. A series of measures such as generating jobs though MGNREGA are being taken for the villagers,” said VK Yadav, chief wildlife warden of West Bengal.

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