deepwater horizon -- 12/22/21
Today's selection -- from The Brilliant Abyss by Helen Scales. The many tragedies of the Deepwater Horizon explosion and oil spill:
"Eleven workers were killed when the Deepwater Horizon rig exploded on April 20, 2010.
"Beyond the human tragedy, the submersible revealed the ecological catastrophe continuing on the seafloor. Over the course of eighty-seven days, approximately four million barrels of oil had poured from the blown-out Macondo wellhead into the Gulf, making it the biggest accidental oil spill in history. (The deliberate oil spill in waters of the Arabian Gulf in 1991 during the Gulf War may have been bigger.) A huge oil slick formed at the surface, polluting coastlines from Louisiana to Florida; salt marshes and beaches were oiled; thousands of dolphins and turtles were killed; a generation of fish larvae may have been poisoned and lost; toxins seem to have caused cardiac defects and triggered heart attacks in bluefin tuna and amberjack; and for a time, because of the contamination, a third of the Gulf of Mexico was closed to fishing.
"The disaster was tragic enough at the surface, but a great deal of the spilled oil never left the deep. Around 3,300 feet down, a plume of oil and injected dispersants spread over hundreds of square miles. A lot of the oil that did float to the surface subsequently sank back down. Oil-covered plankton and particles of marine snow stuck together and fell much faster than normal, in what came to be known as a dirty blizzard.
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| The oil seen from space by NASA's Terra satellite on 24 May 2010 |
"'We saw this dark line on the seafloor,' [marine biologist Clifton] Nunnally said, recalling the 2017 dive to the Deepwater Horizon. The abyssal plain had been the regular, pale beige color except for this meandering mark. The submersible followed the line and at the end found a crab crawling hesitantly along, leaving a trail exposing the black oil just below the surface. In the seven years that had passed since the waters above had cleared of oil, only a thin layer of clean marine snow had fallen and covered over the blackened seabed. All it took was one crab to scratch the surface and show what lay below.
"In the months immediately after the Deepwater Horizon disaster, the surrounding seafloor transformed into what many have described as a toxic waste dump. Dead bodies of sea cucumbers, sponges, and sea pens lay scattered around. Deepwater corals were smothered and poisoned by a mix of oil and dispersant. During the cleanup, some 766,000 gallons of chemical dispersants were injected directly into the wellhead, something that had never been done before. The dispersants boosted bacterial decomposition of the oil, stripping oxygen from the water and suffocating deep ecosystems. The dispersants also turned out to be more toxic to deepwater corals than oil.
"Seven years after the spill, the ecosystem had barely begun to recover, and alarming, unexpected things are still happening. The oily chemicals are proving to be toxic enough to keep many animals away. Around the wellhead are none of the species that are common in other, healthier parts of the Gulf no flytrap anemones, no sea cucumbers, no giant isopods. The sunken wreckage of the Deepwater Horizon drilling rig itself remains chillingly devoid of life. Usually, when a hard structure appears on the oozy abyss, a flock of animals swoops in to take advantage of the firm footing. Something is keeping them away from the Deepwater Horizon, likely a combination of the decomposing oil and dispersants.
"During the 2017 dive, the only animals [marine ecologist Craig] McClain and Nunnally saw near the wreckage were evidently not doing well. Crabs with festering shells, as if they hadn't molted properly for some time, were clustered around the wellhead in much higher numbers than normal and shuffling around like zombies. McClain and Nunnally's theory is that crustaceans are attracted by degrading hydrocarbons, which mimic the chemical signals of natural sex hormones. Once the crabs are drawn to the wellhead, the toxic environment makes them too frail to leave. McClain likens it to La Brea Tar Pits in Los Angeles, which millions of years ago entrapped mammoths, giant sloths, and saber-toothed cats."
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