What lies beneath the seafloor? Results from first microbial subsurface observatory experiment

During the four-year subsurface experiment, the research team deployed the first in situ experimental microbial observatory systems below the flank of the Juan de Fuca Ridge, which is located off the coast of Washington (U.S.) and British Columbia (Canada).

Becker and UM Rosenstiel alumnus Andrew Fisher installed the sub-surface observatory technology known as CORK (Circulation Obviation Retrofit Kit), which seals the sub-surface borehole for undisturbed observations of the natural hydrogeological state and microbial ecosystem inside Earth's crust.

"Similar to a cork in a wine bottle, our technology stops fluids from moving in and out of the drilling hole," said Becker, a UM Rosenstiel School professor of marine geology and geophysics. "Ocean water is blocked from entering the hole and flushing out the natural system."

These natural laboratories allow scientists to investigate the hydrogeology, geochemistry, and microbiology of ocean crust.

A large reservoir of seawater exists in Earth's crust, which is thought to be the largest habitat on Earth. This seawater aquifer supports a dynamic microbial ecosystem that is known to eat hydrocarbons and natural gas, and may have the genetic potential to store carbon. Scientists are interested in better understanding the natural processes taking place below the seafloor, which also give rise to economically important ores along the seafloor and may play a role in earthquakes.

"The paper is important since it is the first in-situ experiment to study subsurface microbiology," said Becker, a co-author of the paper.

The History Channel program, "Journey To The Earth's Core," which aired last month discusses the ongoing research of Becker, UM Rosenstiel School Ph.D. candidate Katherine Inderbitzen, UM alumnus and Expedition Co-Chief Scientist Andy Fisher and more than 20 other scientists and educators from around the world aboard the scientific ocean drilling vessel JOIDES Resolution. The eight-week Integrated Ocean Drilling Program (IODP) expedition installed two new subseafloor CORKs.

The new research paper, "Colonization of subsurface microbial observatories deployed in young ocean crust," was published in last month's issue of Multidisciplinary Journal of Microbial Ecology, a publication of the journal Nature.

The paper's co-authors include Becker, Beth Orcutt and Katrina Edwards from the University of Southern California, Wolfgang Bach and Michael Hentscher from University of Bremen in Germany, Andrew Fisher from the University of California Santa Cruz, Brandy Toner from University of Minnesota and C. Geoffrey Wheat from the University of Alaska.