Twelve crew members were rescued on Wednesday after a Bangladeshi vessel carrying fly ash from West Bengal to Khulna capsized in the Muri Ganga river in South 24 Parganas, police said, raising concerns about potential harm to the estuary’s aquatic life and fragile ecosystem.

A Sundarban police officer said, “A Bangladesh-bound vessel — MV Tamzid Nasir — transporting fly ash from Budge Budge capsized in the Muri Ganga. There was one Indian and 11 Bangladeshi crew members on board. Nearby vessels rushed to help, and all the crew members were rescued.”

Fly ash contains heavy metals that can leach into water, posing risks to both aquatic life and human health. Environmentalists and local fishermen warned that such incidents threaten the ecologically sensitive estuary.

Milan Das, general secretary of the Dakshin Bangla Matsyajibi Forum, a fishermen’s association, said, “Every time a vessel carrying fly ash sinks in this part of the delta, an area of about one kilometre becomes almost lifeless for the next six months. Fish disappear, and the impact is long-term. The capsized vessel also poses risks to other fishing boats and nets nearby.”

The transportation of cargo along this route is governed by a 1972 agreement between India and Bangladesh. However, accidents near Sagar Island, part of the Sundarban delta, have occurred before.