The oil spill occurred when a tanker collided with another vessel and sank on December 9in the Bangladesh side of the Sundarbans forest, the world's largest single block of mangrove forest straddling the delta where the Ganges and Brahmaputra Rivers flow into the Bay of Bengal. The oil has spread over a 350-square-kilometer area of channels and creeks of various sizes.

Two days after the collision, an Irrawaddy dolphin carcass was found afloat 25 kilometers from the accident site. Although there is no confirmation that the animal's death was caused by the oil spill, residents have been quoted by German news agency DPA as saying they have hardly seen any dolphins in the area since the spill. Three wildlife sanctuaries in the eastern Sundarbans were declared in 2012, after studies by the Wildlife Conservation Society identified them as 'hotspots' for Ganges River and Irrawaddy dolphins.

Dr. Anurag Danda, an expert on the Sundarbans at the World Wildlife Fund (WWF) in India, says in a DW interview that the extent of the damage to the forest - the world's only mangrove forest with tigers - caused by the oil spill will only be local, with possible deaths of aquatic species due to a drop in oxygen.

DW: How would you describe the extent of the damage caused by the oil spill?

Dr. Anurag Danda: The extent of damage will be high locally - spread over about 100-150 square kilometers - with possible deaths of aquatic species due to drop in oxygen, as well as among burrowing creatures such as crabs and mudskippers.

Plants with pneumatophores will also be adversely affected. The Sundarbans in its entirety is unlikely to be affected since the estuaries are north-south aligned; east-west dispersal is limited. Moreover, Dolphin deaths have already been reported and the first photograph of a dead dolphin was released recently.

What are the authorities doing to clean the area?

Bangladeshi authorities have closed the river route to traffic. Vessels have been sent to contain the spill but I am not aware of any expertise in this part of the world to deal with oil spill in an estuary. The international community could and should help with a long term ecosystem damage assessment study.

Villagers are being encouraged to remove as much oil as possible and they are resorting to manual scooping and containment through use of banana plants, bamboo poles and fishing nets.

How important are the Sundarbans for Bangladesh?

For Bangladesh, the Sundarbans is the most important natural area. The area has been declared World Heritage Site. There is no human habitation in the Sundarbans forests in Bangladesh but resources are extracted. These are fish and crabs, fuel wood, and thatching material. The Sundarbans in Bangladesh harbour three wildlife sanctuaries besides a dolphin sanctuary (close to the accident site).

Are people directly affected by the spill?

People dependent on fishing and crab hunting are directly affected and will remain so for a fairly long time even after the spill has dispersed due to expected large scale mortality of fish and crabs in the spill affected area.

How could such oil spills be avoided in the future?

This spill is a result of sheer negligence. During this time of the year, the Sundarbans forests are enveloped in thick fog in the morning with visibility down to zero. Visibility is restored to normal usually not earlier than 8 a.m. and vessel traffic must be halted compulsorily until visibility is restored.

In India, vessel traffic is not permitted through the Tiger Reserve or the National Park/Sanctuaries. Bangladesh could do the same, but this means finding alternative routes, which is not always easy due to very low draft in some of the creeks due to siltation.

Dr. Anurag Danda is head Climate Change Adaptation Programme and Sundarbans Landscape at the World Wildlife Fund (WWF) in India.