A week after a high-profile paper suggested that the vast Deepwater Horizon oil plume could linger for months, another study claims bacteria are breaking the oil down quickly, and that the plume is likely gone.
The conflict between the results are striking. Other researchers warn that there’s just too little data to draw any conclusions. But the new findings are at least encouraging.
“We saw the same plume they did,” said Terry Hazen, an ecologist and oil spill specialist at the Lawrence Berkeley National Laboratory, whose research is funded in part by BP. “We found that very large proportions of genes from water in the plume have the ability to produce enzymes that break down the oil.”
As with last week’s study, Hazen’s involved samples taken from the deep-sea oil plume that in late June was 22 miles long, one mile wide and 650 feet thick, and was published in Science.
The previous study, led by researchers from the Woods Hole Oceanographic Institute, found few signs microbial activity around the oil. From those measurements, it seemed that months would pass before bugs broke down the oil.
The WHOI team didn’t look directly at bacteria in the water, but used oxygen depletion — caused by bugs multiplying and going into metabolic overdrive while eating — as a sign of their activity.
By contrast, Hazen’s team extracted microbial DNA from plume water samples, sequenced the genes and identified their functions. Many of the genes produce enzymes that break down some of the compounds in crude oil.
The researchers also identified a previously-unknown strain of ostensibly oil-gobbling Oceanospirillum that doesn’t consume oxygen. Its activity would have gone unnoticed by the WHOI team.
“That particular species becomes dominant in the plume. It out competes some of the other bacteria that are normally present. It can break down the oil quite well,” said Hazen, who noted that the Gulf’s deep-sea microbes have evolved to handle crude oil that seeps naturally from the seafloor.
When Hazen’s team put oil samples in a laboratory setup designed to mimic Gulf conditions, it had a half-life of between one and six days. And according to Hazen, the researchers have found no sign of the plume in the last three weeks, suggesting its breakdown.
via Oil-Gobbling Bug Raises Gulf Hopes … for Now | Reuters.
This study has its critics too. But their bottom line is that we just don’t know.
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