The United States and the United Nations are sending experts to Bangladesh to assess the impact and potential cleanup of a serious oil spill that threatens the Sundarbans, a globally important mangrove ecosystem and home to endangered river dolphins.
Nearly 350,000 liters of oil spilled into the world's largest mangrove forest on 9 December, after a tanker carrying furnace oil collided with another vessel. The spill occurred within the Chadpai Wildlife Sanctuary, part of the 140,000-hectare Sundarbans—a mangrove-rich UNESCO World Heritage Site known for its exceptional biodiversity.
Bangladesh’s “government was totally unprepared for this,” says Brian D. Smith, director of the Wildlife Conservation Society’s Asian Freshwater and Coastal Cetacean Program. “There were some real jurisdiction problems. … It wasn't clear who was in charge.”
Although the waterway where the spill occurred is within the Sundarbans, which is under the remit of the Forest Department, navigation falls under the Ministry of Shipping. “Everybody kept deferring to the Ministry of Shipping, since they were the ones clearly the most in charge … but they were nowhere to be found,” Smith says.
When the tanker was finally brought onshore, only 200 liters of the heavy oil remained, according to Bangladeshi officials. “We can assume that virtually all the oil escaped into the Shela channel and spread from there” throughout the eastern Sundarbans, says Elisabeth Fahrni Mansur, director of training and Education for the Wildlife Conservation Society’s Bangladesh Cetacean Diversity Project in Khulna. The oil’s viscosity is a double-edged sword for the environment—the heavy oil did not disperse as fast as lighter oil would, but it also means that much of the oil is being retained in the structure and woody debris of the mangrove forest.
Mangrove forests are the tropical ecosystem that is most sensitive to oil spills, according to an environmental sensitivity index developed by the U.S. National Oceanic and Atmospheric Administration (NOAA). The trees are highly susceptible to the physical effects of oiling, according to the NOAA report Oil Spills in Mangroves: Planning and Response Considerations. The oil is toxic and can block specialized tissues used for respiration and salt management. Experts are also concerned that one forest inhabitant—the mud crab, which burrows along the channel bed—could increase the persistence of oil in the area. “The oil will settle into these networks of tunnels and burrows and create oil slicks for years and possibly decades to come,” Mansur says.
Jennifer Lewis, director of the Tropical Dolphin Research Foundation in Alexandria, Virginia, is particularly concerned about the impact the spill will have on two rare river dolphin species: the Irrawaddy and Ganges river dolphins. Conservationists fear the spill could harm the dolphins’ food supply, either by contaminating prey fish and crustaceans or by depleting prey populations.
One dead Irrawaddy dolphin was discovered 2 days after the spill, Smith says. Although the death can’t conclusively be linked to the spill, it’s pretty coincidental, he adds. “We don’t encounter Irrawaddy dolphin carcasses very often.”
Smith says the spill could have been prevented. He is in the final stages of helping write a management plan that would, if adopted, prohibit boats from anchoring inside the wildlife sanctuaries when the accident occurred. But the Bangladesh Inland Water Transport Authority, which has jurisdiction over the area, has held up the process. “We haven't been able to get any cooperation from [them],” Smith says.
The government of Bangladesh has temporarily closed the Shela channel to commercial traffic, which is a major hardship because it is the main oil shipping route for several major cities. Prior to 2012—the same year the wildlife sanctuaries were established for the dolphins—oil carriers used a different channel, but it became silted up. The shipping was redirected through the Sundarbans.
The Wildlife Conservation Society in Bangladesh has put together a brief advising the government on how to mitigate damage from the spill if they decide to reopen the Shela to traffic. It recommends keeping the route closed for at least 2 to 3 hours at high tide or limiting vessels to the absolute minimum speed required to maintain navigability. “What's happening is that at high tide, you get the wakes of these vessels, and they're a meter, meter and a half high,” Smith explains. “So every time these wakes go, it just pushes that oil farther and farther into the forest.” As the new moon approaches and with it higher tides, he says, these recommendations are especially critical.
Smith reports that several government officials have called the oil spill a wake-up call, saying that they need to be much better prepared in the future. That mean improving available cleanup equipment and clarifying government policy regarding who is in charge and how agencies will coordinate cleanup efforts. ”People tried to do the right thing after it happened, but they didn't necessarily have the capacity, and they didn't have the preparation,” Smith says.
In the meantime, Smith has asked the United Nations Development Programme (UNDP) to provide assistance to the local people who have been cleaning up the spill with spoons, sponges, and anything else on hand. Hired by the Padma Oil Company to collect the spilled oil, the villagers lack protective gear, adequate equipment for storing the oil, and safety training.
Smith recounts how when cleanup first began, villagers from one settlement were gathering water hyacinth, which tend to collect a lot of oil, and piling it up onshore not far from the village well, where the oil could contaminate the drinking water. To prevent such problems, he’s been working with UNDP to ensure that collection sites are lined with plastic. Bangladeshi authorities have also been asked to apply for emergency assistance from a U.N. emergency fund. The team of U.S. and U.N. experts is expected to arrive in Bangladesh on Sunday.
In the meantime, researchers worry that the Sundarbans, already a fragile and struggling ecosystem, is facing a critical moment. “Disastrous events like this oil spill can easily tip the scale,” Mansur says, especially by threatening top predators such as the Sundarbans tigers, crocodiles, and dolphins. “Once we lose those protectors of the forest, there’s nothing holding back its total destruction by humans.”