New Study Shows Methane from BP Oil Spill Has Been Eaten by Microbes

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Other scientists who had seen the paper ahead of release, however, expressed skepticism of the idea of a sudden spurt in the population of methane-eating microbes three months after the blow-out. The study should also not be construed as an all-clear for the Gulf, scientists warned.

A study due later this month from Samantha Joye, a University of Georgia oceanographer, provides evidence that much of the oil not recovered from the Gulf sank to the ocean floor.

Joye's team found heavy deposits of oil in the sediment in a 2,600 sq mile area from the well, including remnants of oil that had been burned on the surface.

Under a UV camera, which shows oil as a bright lime green, "it looks like someone has come with a paintgun and just splotched all over the bottom," she said. "You can visibly see: it lights up like a Christmas tree."

She also said she had seen dead corals and heavily oiled crabs on the ocean floor.

It is also unclear what effect the oil and gas had on marine life – such as fish eggs – in the deep water before it was consumed by the microbes. "The book is only partially written here in terms of the impact," Murawski said. "The real question is going to be: did it leave any lasting effects in the ecological population – the invertebrates, turtles, whales, fisheries?"

Several scientists have tried to flesh out the role played by the microbes in scrubbing the Gulf of the oil that never made it to the surface or the shore.

A team from the Woods Hole Oceanographic Institute published a paper in Science last August documenting a 22-mile underwater plume of tiny oil droplets. The team said the oil was very slow to degrade.

One week later, Science published a paper from another team, from Lawrence Berkeley labs, saying the plume had been eaten by undersea microbes.

By mid-September, the picture shifted once more. A new paper, also involving Kessler and his team, suggested that while ethane and propane were being quickly consumed by bacteria, methane was being consumed at a far slower rate.

"It really is a scientific puzzle," said Kessler. "We are just now beginning to get to a stage to see all the data that has been collected to date, to start to tell a comprehensive story."