Massive deep-sea coral die-off discovered near Gulf of Mexico

Scientists have discovered a massive deep-sea coral die-off this week about 7 miles (11 kilometers) southwest of the source of the Gulf of Mexico oil spill.

Large communities of several types of bottom-dwelling coral were found covered with a dark substance at depths of about 4,600 feet (1,400 meters) near the damaged Deepwater Horizon wellhead, according to a scientific team on the National Oceanic and Atmospheric Administration (NOAA) ship Ronald H. Brown.

"The coral were either dead or dying, and in some cases they were simply exposed skeletons," the National Geographic News quoted the team member Timothy Shank of Woods Hole Oceanographic Institution, as saying.

"I've never seen that before. And when we tried to take samples of the coral, this black-I don't know how to describe it-black, fluffylike substance fell off of them," Shank added.

About 90 percent of 40 large groups of severely damaged soft coral were discolored and either dead or dying, the researchers say. A colony of hard coral at another site about 1,300 feet (400 meters) away was also partially covered with a similar dark substance that's likely oil from the BP spill.

"Corals do die, but you don't see them die all at once," said cruise lead scientist Charles Fisher of Penn State University.

 "This ... indicates a recent catastrophic event."

The circumstantial evidence is strong enough to be considered a "smoking gun"-proof that the BP spill was the culprit, Fisher said in a statement.

The research cruise is the most recent leg of a four-year study of deepwater coral in the Gulf of Mexico. Deepwater corals, which are prevalent in the deep Gulf, are actually dependent on oil and gas.

That's because natural gas seeps attract microbes that result in rock formation, providing a hard surface for the coral to grow on. Over thousands of years, a diversity of corals has built communities at these depths, which are often difficult to access and study. 

In light of the Gulf oil spill, in 2010 the research team focused on finding oil-related impacts to Gulf coral. The dead coral-found in an area of about 50 by 130 feet (15 by 40 meters)-was spotted during the final dive of a three-week cruise. Previous expedition dives had revealed no visible damage to coral in other parts of the Gulf.

"We were hoping not to find anything," Shank said.

Penn State's Fisher added, "We were looking for subtle changes. ... What we saw was not subtle," Shank added.