Deep sea microbe populations are evolving in response to the Deepwater Horizon disaster, helping to digest the oil that continues to contaminate the Gulf of Mexico, according to a study published today (August 24) on the ScienceExpress website.

Bacteria on an oil drop (magnified 100x) Image: © Science/AAAS

The findings provide tantalizing clues that the ocean is evolving in a way that will help it heal from the massive spill, but it's still early days, said biogeochemist John Farrington of the School of Marine Science and Technology at the University of Massachusetts-Dartmouth, who was not involved in the research.

"We shouldn't get all a warm fuzzy feeling that the problem has gone away," Farrington told The Scientist. Recent data out of the Gulf "are very exciting advances in our understanding of spilled oil in the ocean, but there's still a lot of work to be done."

By sampling the microbial communities both within and beyond the oil plume, Terry Hazen of Lawrence Berkeley National Laboratory and his colleagues found increases in several bacteria varieties within the oil's reach, nearly all of which are related to species known to degrade hydrocarbons, like those found in oil. They further determined that these bacteria appear to be degrading the hydrocarbons.

"These results ... imply that there exists a potential for intrinsic bioremediation of oil contaminants in the deep-sea, and that oil-degrading communities could play a significant role in controlling the ultimate fates of hydrocarbons in the Gulf," the authors wrote in their report.

"There are bacteria out there that really make a living off of degrading oil," said biological oceanographer William (Monty) Graham of the Dauphin Island Sea Lab and University of South Alabama. "The paper shows that [the bacteria] were able to respond quite quickly to the presence of the oil."

Oil droplets dispersed (magnified 100x) Image: © Science/AAAS

However, he added, who did not participate in the study, the researchers specifically looked at a particular component of the oil, the relatively short-chain alkanes, that degrade relatively rapidly. "Short chain stuff goes away very quickly," said Graham, who did not participate in the study, "but the other more complex materials may in fact take much longer."

Indeed, another report published in ScienceExpress just last week indicated that another component of the oil, known as monoaromatic hydrocarbons, would take more than a month to degrade. "Oil is a deceptively simply three letter word to describe something that is extremely complex," Graham said. "It comes out with a great number of different constituent parts to it, and how oil goes away in the ocean depends on the rates of how all those different parts go away."

Still, the results do provide important information about how long it will take the ocean to return to normal. "It's extremely important to not just know that the ocean is going to deal with [the oil] on its own, but how long and how far spread is the material going to be before it does return back to a pre-spill concentration," Graham said. To do this, "we need to know the information about the rates of microbial degradation."

Future work will need to look both at the degradation rates of the other oil components and the effects the lingering elements have on nearby organisms, Farrington said. "Most of the toxicity studies that have been done on oil have been done on shallow water organisms, and we just do not understand the midwater ecosystems and organisms in the same detail," Farrington said. "This is a large experiment in progress."


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Scientists brace for oil impact
[17th May 2010]