The Impact of Oil Spills on the Deep Sea: the Deepwater Horizon Oil Spill

The Louisiana University Marine Consortium (LUMCON) published in September 2019 a study on the Deepwater Horizon Oil Spill in Royal Society Open Science.  The BP’s Deepwater Horizon oil rig exploded in April 2010, killing 11 workers.  The subsequent cleanup and restoration had cost nearly $65 billion..but while while we can burn off and disperse oil on the surface, but we don’t have the technology to get rid of oil on the seafloor. So approximately 10 million gallons of it settled there….In 2017 , the The LUMCON surveyed the site surrounding the wreck of the rig, and another one 1,640 feet north. There were no giant isopods, glass sponges, or whip corals that would have jumped (metaphorically) at the chance to colonize the hard substrate of the rig, such as discarded sections of pipe…..But]  crabs were just about everywhere. The researchers were shocked by the sheer number of crustaceans and other arthropods that had colonized the spill site. According to rough estimates, Atlantic deep sea red crabs, red shrimp, and white caridean shrimp were nearly eight times more populous at the Deepwater site than at other spots in the Gulf. “Everywhere there were crabs just kicking up black plumes of mud, laden with oil,” Nunnally says. But abundance does not mean the site was recovering, or even friendly to life. Particularly eerie was the crab’s achingly slow movement. “Normally, they scatter when they see the ROV lights,” he says. But these crabs seemed unbothered, or unaware of the robot’s presence.

Crabs on the seabed of the Deepwater Horizon oil spill

The researchers hypothesize that degrading hydrocarbons are what’s luring unwitting crabs from the surrounding seafloor to the deep-sea equivalent of a toxic dump. “The chemical makeup of oil is similar to the oils naturally present on crustaceans,” Nunnally says. “They’re attracted to the oil site, but everything goes downhill for them once they’re in the area.” A similar kind of chemical confusion occurred at an oil spill in Buzzards Bay in New England in 2003, which attracted hordes of American lobsters. The researchers liken the death trap to the La Brea Tar Pits: Once lured in, the crabs lose their ability to leave. With no other species able to thrive in the area, the crabs have no food source—except each other. And as one might imagine, consuming the flesh of a toxin-riddled crab or starving to death in a deep-sea tar pit is sort of a lose/lose situation.

The crabs also looked anything but normal: some claws shrunken, some swollen, shriveled legs, a dusting of parasites. “There were deformities, but mostly things were missing,” Nunnally says. “You come in with eight legs and try to get away on four or five.” The researchers have yet to ascertain what specific toxins led to these maladies. The shrimp looked just as awful as the crabs. “They didn’t look like shrimp from other sites,” Nunnally says, adding that many of the small crustaceans had humps in their backs—tumors, perhaps.

Excerpts from SABRINA IMBLERS, A Decade Later, the Deepwater Horizon Oil Spill Has Left an Abyssal Wasteland, Atlas Obscura, Sept. 18, 2019

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