Threatened dolphins of Sundarbans

Tuesday's oil spill following the sinking of a tanker vessel with a huge quantity of furnace oil will seriously threaten the Irrawaddy dolphins in the Sundarbans, experts say.

The mangrove delta is home of this increasingly endangered species that is found in discontinuous subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal and Southeast Asia.

The Chandpai range in southern Sundarbans is where they are mostly found -- which is why the area along with two others in the Sundarbans was declared as Dolphin Reserve in 2011.

But it is near Chandpai that the oil tanker sank in the Shela River on Tuesday, causing an oil spill yet to be fully controlled. It was carrying 350,000 litres of furnace oil.

"Due to the twice-daily cycle of tide and ebb in the Sundarbans, the oil is spreading out dangerously in all directions from north and south. Photographs from the area show a north-south oil line. Then it will spread from east to west," says Rubaiyat Mansur of the Bangladesh Wildlife Conservation Society.

"This is simply disastrous for the Irrawaddy dolphins in the area."

The Sundarbans has been home to several species of dolphins -- Indo-Pacific hump-back dolphins, finless dolphins, Indo-Pacific bottle-nose dolphins, Spinner dolphins, Porpoise dolphins, spotted dolphins and Gangetic river dolphins.

The Brides variety of whales are also found in the area. Dolphins are close to whales.

"The Sundarbans are known the world over as the favourite habitat of the Irrawaddy dolphins. "The western Sundarbans have the highest concentration of this endangered species and it is precisely there that the oil spill has occurred," says Rubaiyat.

Bangladesh Forest Department's Conservator (wildlife) Tapan Kumar Dey agrees.

"The dolphins flung themselves out of water every 20/25 minutes, With the dense furnace oil, that is as thick as diesel , at the top of the water , the dolphins will have real trouble breathing," says Dey. "This is a huge disaster for the dolphins."

The spilled off oil reaches the banks of the river. Photo: Rubaiyat Mansur, Bangladesh Wildlife Conservation Society

Irrawaddy dolphins plying on the rivers. Photo: Rubaiyat Mansur, Bangladesh Wildlife Conservation Society

Wildlife diversity specialist Pavel Partha fears a sharp drop of oxygen in the waters of Sundarbans due to the oil spill. "All aquatic animals, specially the dolphins, will face a huge crisis."

Wildlife Trust Bangladesh's Chief Executive Anwarul Islam fears this oil spill could endanger the entire eco-system of Sundarbans.

"I am not sure whether the oil spilled is heavy or light. If light, it will float and spread to the various small rivers in the delta, but if it is heavy, it will spread after settling on the river bed," said Partha. "Either way, it will spread."

Partha feared it will not only threaten aquatic animals but others living on land who consumes water on the river banks.

"I fear it will cause huge damage to the entire eco-system of the Sundarbans -- fish, deer, monkeys and aquatic plants will all be affected." "As it is, the Sundarbans eco-system is fragile and this oil spill will now cause huge damage. The impact will linger for long," says Islam.

Conservator Tapan Kumar Dey said the migratory birds that flock to the Sundarbans in winter will miss out on food they fish out of water.

On Tuesday, oil tanker 'OT Southern Star 7' was hit around 5am at the Chandpai Range of Sundarban's West Zone in Bagerhat by another cargo vessel. It sank soon after.

Quoting the owners, the Coast Guard officer said that the ship started for a power plant in Gopalganj on Monday afternoon from the Khulna Old Depot carrying 357,664 litres of furnace oil.

"The ship was anchored on the Shela River at the forest's Chandpai Range during the night. It started around 5am amid dense fog. After a while an empty cargo ship 'Total' rammed it from behind."

The cargo ship was heading to Chittagong after unloading at the Mongla Port in Bagerhat.

Conservator Tapan Kumar Dey says the forest department just does not have the capability to control the oil spill. "So the furnace oil has spread rather quickly."

Irrawaddy dolphins plying on the rivers. Photo: Rubaiyat Mansur, Bangladesh Wildlife Conservation Society

Assistant Forest Conservator at Chandpai Range Abul Kalam Azad feels the entire stock of oil in the tanker has spilled over into the Shela River. The oil has spread up to 20 kms inland from the point of spillage, he said.

By evening, the oil slick could be spotted at Joimoni, Beltola, Nandbala, Andarmanik and Mrigmari .

Mongla Port Authority chairman Habibur Rahman Khan suggested using navy ship' BNS Shahid Ruhul Amin' to control it, since it had the capability to do so.

In 1997, the Unesco declared the Sundarbans as a world heritage site . After that, several measures were taken to protect its eco-system and the wildlife in its mangrove forests.

Chittagong university's forestry professor Kamal Hossain told bdnews24.com that this oil spill has come at a time when UNESCO was pushing Bangladesh and neighbouring West Bengal hard to preserve the world heritage status of the Sundarbans.

"This could not have happened at anytime worse."