Living organisms surviving under 300 feet of solid rock and sediment at the bottom of the ocean may sound like something from Jules Verne, but a team of researchers led by UH scientist James Cowen have found them in a deep borehole in the northeast Pacific. Their work was recently published in the journal Science.
“As more research such as this is done, we’ll probably continue to be surprised at just how far down we can find life within the Earth, and the many different environments under which it’s able to exist,” said Michael Rappe, a member of the team from Oregon State University, to the Geological Society of London.
The microscopic life was found in 149-degree fluids (65 degrees Centigrade) coming from a borehole through ocean crust thought to be 3.5 million years old. On the top of the borehole, scientists installed a type of seal called the Circulation Obviation Retrofit Kit (CORK) that allowed them to sample these fluids that had previously been inaccessible.
The researchers found microbial growth of bacteria and archaea, which are found in extreme environments. One organism was found to be closely related to those that inhabit a Yellowstone National Park hot spring.
The organisms were growing without the need to consume organic molecules, as most life on Earth does. They instead process carbon dioxide and inorganic molecules such as hydrogen and sulfide.
Cowen told the Honolulu Star-Bulletin that the researchers want to isolate the organisms, raise them in culture “and test them for what they can do.”
When they compared the seawater at the ocean floor with seawater from the borehole, the researchers found lower amounts of sulfate and magnesium, and elevated amounts of ammonia. This means that the fluids reacted with ocean crust, and that organisms have been living there and metabolizing sulfate.
“This work collects and analyzes crustal fluids where organisms are living and growing to an extent never before possible,” Cowen said in a recent UH press release. “The ocean crust is a huge frontier. It’s in our world, and we know very little about it.”
Life within the ocean’s crust is usually associated with high-temperature environments at Mid-Ocean ridges. This new research took place on the flank of the mid-ocean ridge, which is much more difficult to access.
“Thus, our data support the hypothesis that life in the ocean crust is not limited to high-flow hydrothermal systems within new ocean crust, but also extends to low-flow older crust of the mid-ocean ridge flanks,” the authors concluded in their Science paper.
The fieldwork was conducted in 1998 and 1999 onboard two research ships, the Atlantis from the Woods Hole Oceanographic Institution and the Thomas G. Thompson from the University of Washington. The remotely operated vehicle Jason and the submersible Alvin, both from Woods Hole, were used for the dives.