Scientists study microbes beneath ocean floor

WOODS HOLE, Mass., April 6 (UPI) -- Surprisingly, some microbes thrive beneath ocean floor, and are often found near hydrothermal vents. For the first time, scientists have studied in detail the microbial community living inside dense, rocky crust under the colder North Pond, along the Mid-Atlantic Ridge.

The microbes were found within rock samples collected by an ocean floor observatory installed by the Integrated Ocean Drilling Program in 2011. The observatory is situated on the North Pond, a small depression where sediment collects along the western flank of the Mid-Atlantic Ridge.

Microbes living in the rock were well oxygenated, heterogeneous and quite different from microbial communities found in seawater collected at the bottom of the ocean.

Though the crust is beneath the ocean floor, it's not isolated from water. Tremendous pressure pushes the water into the tiniest of crevices in the crust. Researchers believe the aquifer flowing through this deep-lying rock circulates the entire ocean's volume every 200,000 years.

Previously, researchers have focused on microbial communities at and under the ocean floor near hydrothermal vents. Their latest efforts focused on much more frigid environs.

"The cold crustal aquifer is a different environment that is also globally important not just in terms of life, but biogeochemical cycling," Julie Huber, a researcher with the Marine Biological Laboratory at Woods Hole, said in a news release. "We are only starting to discover how things proceed there."

Researchers described these unique environments and the microbes they host in a new paper published this week in the journal Scientific Reports.

[Correction: A previous version of this story said this was the first study of microbial communities under the ocean floor. It is the first to describe the microbial communities under the North Pond, specifically.]