Nearly ten years after worst oil spill in American history, the seafloor around the site of the Deepwater Horizon disaster is teeming with life. But that life is not very diverse and most of the shrimp, crabs and other crustaceans lured to the oil-contaminated seabed are not doing well at all.
Researchers from the Louisiana University Marine Consortium (LUMCON) sent a remote-operated vehicle (ROV) 6,000 feet down to the site of the accident in 2017, they describe in the journal Royal Society Open Science. The ROV captured the first images of the epicenter of the spill since 2014 and surveyed the area within a third-of-a-mile radius from the wellhead. Over the course of 87 days in the spring of 2010, the well spewed four million barrels of oil into the Gulf of Mexico before it was finally capped.
In photos, it appeared to be a blackened wasteland, reports Sabrina Imbler for Atlas Obscura. The normal denizens of the deep-dwelling sea cucumbers and corals were missing.
“The prior week, we had done dives across the Gulf of Mexico and saw, you know, glass sponges and squids and fish and whip corals and giant isopods, one of my favorite deep sea animals,” Craig McClain, study author and executive director of LUMCON, tells Carol Off at CBC Radio’s As It Happens. “It was the equivalent of walking around in a tropical rainforest and the next day walking around on a cement parking lot.”
Instead, the seafloor was full in strange crabs and shrimp—all covered with tumors. The crustaceans made up 92 percent of all life seen during the dives. Normally, when hit with the lights of the ROV, crabs will scuttle out of site. These animals, however, just moved around like little ocean zombies. Many had blackened shells, were riddled with parasites or had missing claws and legs.
“What we observed was a homogenous wasteland, in great contrast to the rich heterogeneity of life seen in a healthy deep sea. Crabs showed clearly visible physical abnormalities and sluggish behavior compared to the healthy crabs we had observed elsewhere,” McClain tells Christina Zdanowicz at CNN. “Once these crustaceans reach the site, they may become too unhealthy to leave.”
McClain tells Tristan Baurick at NOLA.com that the team believes that the crabs and other crustaceans are attracted to the area, since degrading hydrocarbons mimic some of the their natural hormones, in particular some associated with sexual attraction. So the crabs and shrimp enter the wasteland expecting to find mates; instead, they end up sick with the sticky oil preventing them from properly molting their shells.
“Once these crustaceans reach the site they may become too unhealthy to leave much like those prehistoric mammals at the Le Brea tarpits,” McClain writes in a post at Deep Sea News.
The species most attracted to the oily mess are not commercially harvested in the Gulf, so the crustaceans are not a direct threat to humans—though there is concern that the contamination could make its way up the food chain.
Imbler reports that while $65 billion was spent on cleaning up the spill and studying its aftermath, little work was done on the seafloor. That’s because there is no way to clean up the inaccessible depths, even though 10 million gallons of oil settled over 1,200 square miles. While the parties involved in the spill have released statements saying the oil remaining on the seafloor is no longer harmful, this findings in this news study beg to differ.
“The deep sea is always out of sight, out of mind,” McClain tells Imbler. “You can burn off and disperse oil on the surface, but we don’t have the technology to get rid of oil on the seafloor.”
Perhaps the most concerning part of the situation is that no one is really studying what is happening at the site. The LUMCON team decided to take a look since they were nearby conducting another study and had a free day to use the expensive ROV. McClain says any funding for studying the area dried up around 2014.
“I’m concerned that there’s not been an increased effort in and continued monitoring of the recovery or the lack of recovery at the site,” he tells Off. “We can't begin to know what restoration of the deep sea looks like until we actually get a handle of how fast it's recovering in the first place.”
The team hopes to have another free day in the near future to try and capture some of the sickly crustaceans near the well head for further study.
While research on the deep-sea consequences of the mega-spill is sparse, scientists are still trying to understand the surface impacts of the incident. Last week, researchers from Florida State University published a paper showing that golf-ball-sized clumps of oil and sand are buried in Gulf beaches, and could take up to 30 years to fully decompose, though larger clumps will take even longer.