Evidence of carbon-eating bugs at 1400 meters surprises scientists
Olivia Mason has found new life deep beneath the ocean floor. The discovery could influence how we respond to global warming gases in the atmosphere.
A recent research expedition on a drilling rig took her to the Mid-Atlantic Ridge, a seismically active line of underwater mountains that rise from the floor of the Atlantic Ocean. Her mission was to collect core samples beneath the sediment and basalt layers on the sea floor to what's called the gabbro, the hard rock layer that forms the upper edge of the earth's mantle.
While the gabbro is usually too deep to be accessible to core sampling, Mason had a lucky geologic break. "At this location there had been extensive faulting and basically those top two layers, the sediment and the basalt had literally been removed because of all of this faulting."
That left the gabbro exposed and enabled drilling through the hard rock. It took nearly four months to reach the 1,400 meter-mark, where samples were collected for Mason's laboratory experiments at Oregon State University. "I literally took that rock sample and powdered it and then extracted microbial DNA from that rock powder."
Mason says what she expected to find were microbes similar to what had already been observed in the basalt layer directly above the gabbro, and chemically identical. What she saw was strikingly different. "Several lines of evidence suggest that there were microbes in these deep gabbro rocks that were able to degrade hydrocarbons like methane. So it looked like there were microorganisms in these rocks that were able to use methane or to oxidize it."
Mason says such bacteria have been observed before in oil reserves and contaminated soil.
While it's not clear whether the microbes migrated down or evolved below the seafloor, research suggests that these microscopic carbon-eaters could play a role in storing carbon produced by climate-changing gases like methane.
"We wouldn't want that methane to escape into the hydrosphere or the overlying seawater and then beyond, given that it's a potent greenhouse gas. So something like methane utilization by these microbes is an important process and one that no one knew was occurring in this environment before."
Mason believes the study is a snapshot of what might be a new ecosystem beneath the sea floor, but concedes that much more work needs to be done before scientists fully understand what these microbes are doing down there. "So that we can start to really understand how important these microbes might be in cycling something like methane."
According to Mason, the next step is to grow these microorganisms in the laboratory, and to do that she'll have to collect more samples from one of the most inaccessible places on the planet. The research is published in the journal PloS One. Olivia Mason is now a research scientist at Lawrence Berkeley National Laboratory in California.