The explosion of BP’s Deepwater Horizon rig on April 20, 2010, marked the beginning of the worst oil disaster in American history. By the time engineers finally capped the well 5,000 feet below the surface in mid-July, some 185 million gallons of crude oil had spilled into the water, contaminating the Gulf of Mexico’s coasts with a thick, rust-colored sludge.
One year on, the gulf appears pristine from above, but the long-term health of the waters beneath the waves remains murky. When University of Georgia biogeochemist Samantha Joye took a submarine to the ocean floor about two miles from the wellhead this past December, she found a devastated seascape. “Everywhere we went there was a layer of material containing oil on the bottom,” she says. “The typical fauna—worms, brittle stars, and sea cucumbers—just weren’t there.” Marine chemist Chris Reddy of Woods Hole Oceanographic Institution (WHOI) says not enough data exist to estimate the amount and distribution of the remaining oil.
Meanwhile, WHOI oceanographer Elizabeth Kujawinski has been studying the 800,000 gallons of chemical dispersant used to break down subsurface oil. She reported in January that it was biodegrading more slowly than projected, remaining detectable in the water at least three months after it was applied. The effects on corals and deepwater fish remain unknown.
Kujawinski and others emphasize that it will be years before the disaster’s full repercussions become clear. Following the 1989 Exxon Valdez spill, she says, it took about two years for the first scientific papers to emerge and more than a decade for ecologists to synthesize that new knowledge into a comprehensive understanding of the environmental impact.