New details have emerged about “self-cleaning” effects in the Gulf of Mexico witnessed in the wake of the Deepwater Horizon oil spill.
Researchers reporting at the American Chemical Society conference revealed details of a cascade of micro-organisms that spring into action to degrade oil.
Research has also outlined how chemical “dispersants” used in clean-up efforts actually frustrate these processes.
However, the long-term effects of the weeks of oil exposure remain unknown.
And concern was expressed about the ultimate resilience of the Gulf.
Terry Hazen of the University of Tennessee, Knoxville, has been studying oil-degrading microbes in greater and greater detail since the disaster, even discovering some that had never been seen before.
They can break down the long-chain carbon-based “alkane” molecules present in oil - and in isolated conditions will even move towards oil.
“They’re really oil-seeking missiles,” he told the meeting.
In a sense, it is no surprise that the seas should host oil-hungry microbes; natural seeps from the ocean floor have been releasing oil into the world’s waters for millions of years.
A 2003 US National Academy of Sciences reportput the annual average of this seepage in the Gulf at 140,000 tonnes.
But Prof Hazen’s research has revealed more of the complex web of microbes that feed on oil - and are in turn fed on.
Through recent studies, most recently in Frontiers of Microbiology, he and collaborators have begun to map the genomes of these microbes and determine which genes contribute to oil-degrading properties when oil concentrations rise.
A release like that of Deepwater Horizon contains a rich mix of carbon-containing molecules - alkanes, methane and what are called polycyclic aromatic hydrocarbons (PAHs), each presenting its own risks to the environment.
The new finding is about methanotrophs, which feed on methane - among the last compounds to be degraded.
Prof Hazen said that the sudden release of methane, rather than slow seeps, created a lucky effect.
“All of a sudden the [methanotroph populations] go up to really high densities and they’re fat and happy - and then [the methane is] gone.” he told BBC News.
“At that point, they degrade anything else that’s there fortuitously, and they’ll degrade it down below what would be usable as a carbon and energy source - so it’s really sort of a ‘deep-cleaning’ effect.
“That’s why I think the Gulf of Mexico is cleaner than you would expect, not only from the oil but from everything else that goes into it.”