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Oil in the Mangroves

An oil spill in the Sundarbans mangrove forests of Bangladesh threatens two already imperiled dolphin species.

Tap, tap, tap. A fisherman hits the side of his boat with a stick.

Beneath the brackish water of the mangrove swamp, a pod of rare freshwater dolphins hears the cue. They start swimming in circles, rounding up nearby fish into one big ball of shimmering silver. The fishermen drop their nets and scoop the ball up. The dolphins pick off any stragglers.

This sort of cooperative fishing between humans and dolphins has been documented in bottlenose dolphins in Brazil and Irrawaddy dolphins in Southeast Asia. The practice is an idyllic example of two species helping each other.

But it’s also the exception to the rule. By and large, where humans go, dolphins suffer. They can get caught in gill nets and sliced up by boat propellers. On a larger scale, human development wreaks havoc on dolphin habitats in the form of dams, freshwater diversions, dredging, and pollution. And then there are oil spills. 

Photo: Frances Voon

Last month, a tanker carrying furnace oil collided with another vessel in the Sundarbans of Bangladesh, a UNESCO World Heritage Site and home to those fishermen-friendly Irrawaddy dolphins. Two days passed before officials were able to tow the tanker to land, enough time for about 52,000 gallons of fuel to flow across 40 miles of the Sela River and into portions of Chandpai dolphin sanctuary. So far, at least one Irrawaddy dolphin has washed up dead; more are expected to follow.

More than a month later, the official cleanup has yet to begin.

Lew Young, a senior regional advisor for the Ramsar Convention Secretariat (an intergovernmental treaty to protect wetlands), says that soon after the spill, the country’s forest department began enlisting the help of local communities, who so far have only been able to remove about 22,700 gallons of the oil. That’s actually pretty impressive, considering the effort consists of a few hundred untrained locals, skimming off the sticky black gunk by hand—with pots, pans, and buckets. Over at Quartz, photographer Arati Kumar-Rao shares his images of the disaster area, some of them depicting children sopping up oil with sponges. (The oil company has offered to buy back the fuel at around $1.50 per gallon.)

One thing the Bangladesh government seems to have done right is to request aid from the United Nations’ Global Disaster and Alert Coordination System. When the UN experts—all four of them—arrived in late December, the Dhaka Tribune reported that they “slammed authorities for failing to organize a proper cleanup effort.” Other international organizations, including USAID, have also begun helping out.

Dealing with any oil spill is difficult, but the fact that the Sundarbans is the most extensive area of mangrove forest remaining in the world makes this one especially challenging. If you’ve never seen a mangrove forest, picture a gnarled mass of long, skinny roots sitting atop a waterway. When the tide goes out, the roots stay put, looking like the trees are standing on stilts. Young says that tides have likely pushed the oil through the forest, deep into its channels and small creeks, making the muck particularly difficult to get to without further damaging the trees.

The swamp’s almost impenetrable nooks and crannies, however, make it a great sanctuary for numerous species—birds like the black-capped kingfisher and the great egret, felines such as the leopard cat and the endangered Bengal tiger. Rhesus macaques, horseshoe crabs, freshwater crocodiles, and even a handsomely spotted little deer called the chital make their livings among the labyrinth. The spill, National Geographic Traveler reports, will affect all of them. Which brings us back to dolphins.

The International Union for the Conservation of Nature considers Irrawaddy dolphins vulnerable, but scientists still don’t know a lot about them. The species (Orcaella brevirostris) is scattered in freshwater estuaries between India and the Philippines. Its population in the Sundarbans, which was discovered just six years ago, is the largest of its kind at around 6,000 dolphins.

The Ganges River dolphin (Platanista gangetica) also calls these mangroves home. Just how many remain is unclear. They haven’t been sufficiently studied in the Sundarbans, but the IUCN designates the mammals as endangered.

So, why was an oil tanker allowed to cruise through a dolphin sanctuary? Well, it wasn’t. The Shele River has been closed to commercial boats since 2011, though the India Times reports that more than 500 large vessels have continued to illegally navigate through it. In a controversial move yesterday, the government reopened a channel within the river to shipping.

Unfortunately, the Sundarbans ecosystem has probably not seen its last disaster. But the current one forces us to think about the kind of relationship we want with the environment. One that is cooperative, where everybody goes home with a full stomach? Or one that is irresponsible, where everybody—child and dolphin alike—goes home covered in oil?

onEarth provides reporting and analysis about environmental science, policy, and culture. All opinions expressed are those of the authors and do not necessarily reflect the policies or positions of NRDC. Learn more or follow us on Facebook and Twitter.

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