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When biological oceanographer Clifton Nunnally of the Louisiana Universities Marine Consortium and his colleagues used an underwater robot to inspect the wreckage around the Deepwater Horizon’s wellhead in 2017, one of the first things they saw was a solitary boot, a somber reminder of the lives lost in the disaster. No one had seen the area up close since 2012. “Everywhere we looked, it was part carnage and part ghost town,” Nunnally says.

On April 20, 2010, an explosion at the Deepwater Horizon drilling rig about 68 kilometers off the Louisiana coast killed 11 workers and triggered the worst environmental disaster in US history. The Deepwater Horizon floated above 1,500 meters of water, and after 74 days of drilling it had almost completed a well extending about five kilometers into the seabed. By the time the Macondo wellhead was sealed off 87 days after the explosion, roughly four million barrels of oil had spilled.

Replicating deep-sea surveys of the area up to 500 meters from the well that had been conducted a few months after it was capped, the scientists “were floored by the absolute destruction that lay before us on the seafloor,” Nunnally says. “The bottom was devastated. We had never seen anything like it in our lives.”

Nunnally and his colleagues found many troubling aspects “of this new deep-sea hellscape,” he says. For instance, none of the artificial structures littering the seafloor had accumulated the corals, sea anemones, sponges, and other invertebrates that often quickly colonize hard surfaces in the deep sea.

Crabs and shrimp were abundant in the area, though they were visibly unhealthy—many had missing or deformed claws, were heavily infested with parasites, and did not display defensive behavior.

The researchers suggest the hydrocarbons from the spill may have attracted the crustaceans by mimicking their pheromones and the site’s toxic nature then took its toll. “Deathtrap is accurate,” Nunnally says.

These findings, Nunnally says, suggest that it will likely take decades for the area to recover from the spill.

One big question researchers still need to answer is why hydrocarbons from the Deepwater Horizon spill are just sitting on the seabed slowly degrading unlike hydrocarbons from natural oil seeps that quickly decay, says University of Georgia oceanographer Samantha Joye, who did not participate in this study. “What’s different about this situation?

“We need to know the answers to these very fundamental questions about how these undersea natural systems respond to perturbations, how they recover, and the timescale of their recovery,” Joye says. “As long as oil and gas operations are happening in these systems, these are questions we absolutely need answers to—it’s not a matter of if, but when, something like this might happen again.”