Researchers to explore hidden world of life beneath seafloor

Studies by Andrew Fisher and colleagues have shown that seamounts provide conduits through which enormous quantities of water flow between the ocean and the rocks beneath the seafloor, as shown in this illustration by Nicolle Rager. New studies will focus on the organisms that live in this "deep biosphere."

Little is known about the subsurface communities of microbial life that inhabit Earth's "deep biosphere" beneath the ocean floor. A new science and technology center funded by the National Science Foundation (NSF) will coordinate the efforts of scientists to explore this hidden realm of life on Earth.

Andrew Fisher, professor of Earth and planetary sciences at UC Santa Cruz, leads UCSC's participation in the Center for Dark Energy Biosphere Investigations (C-DEBI). He will be a co-chief scientist (with Takeshi Tsuji of Kyoto University) on an expedition this summer to the eastern flank of the Juan de Fuca Ridge off the coast of British Columbia, where he has been studying the flow of water beneath the seafloor since the mid-1990s (see earlier story).

"We will be using sensors, maps, samples, and models to determine where fluids move through Earth's crust below the ocean, how quickly, and with what impacts," Fisher said. "C-DEBI emphasizes the deep biosphere, so we will be working at the interface between Earth science and biology."

Katrina Edwards of the University of Southern California (USC) leads C-DEBI, which won a five-year, $25 million grant from NSF. Direct funding for UCSC from the grant will be about $1 million.

"Our mission statement is to understand the extent, function, dynamics, and implication of the existence of a deep biosphere on Earth," Edwards said. "We focus on the marine realm because it is by far the biggest challenge in terms of potential habitat size."

According to Fisher, the amount of water that circulates through the upper oceanic crust is equivalent to the combined flows of all the rivers on Earth. Scientists also estimate that as much as one-third of the Earth's biomass is harbored within this complex plumbing system deep beneath the seafloor.

C-DEBI will explore such fundamental questions as: What type of life exists in the deep biosphere? What are the physical and chemical conditions that promote or limit life? How does this biosphere influence global energy and material cycles such as the carbon cycle? The center will also develop educational and outreach activities to inspire students and the general public.

In addition to USC and UCSC, major partners in the center include the University of Alaska Fairbanks, the University of Hawaii at Manoa, and the University of Rhode Island. The C-DEBI network of researchers, technologists, and educators also includes collaborators at Harvard University, Washington University in St. Louis, University of Bremen, Japan Agency for Marine-Earth Science & Technology, University of Aarhus (Denmark), and University of Delaware.