URI_Research_Magazine_2010-2011_Melissa-McCarthy

multi- and interdisciplinary research

Pioneers of The Deep Biosphere

A diverse group of research scientists working together at the University of Rhode Island’s (URI) Graduate School of Oceanography (GSO), professors Steven D’Hondt, Arthur Spivack, David Smith and marine research scientist Robert Pockalny, have to dig deep to find the answers they are looking for about the nature of life beneath the ocean floor. Their multidisciplinary research takes them not only to the depths of the ocean floor but to questions about life on other planets. Literally. The microbial life that intrigues them exists miles below the surface of the oceans and is shrouded by questions about how it can survive in such an extreme environment. It is dark and cold at the bottom of the sea and little plant life exists for these subsurface communities to feed on. So what do they eat? And how much energy do they need to live? These are just some of the questions this research group has been trying to answer in research that has taken them on two international ocean drilling expeditions, the most recent in the fall of 2010, to extract sediment that is up to a hundred million years old. In the process, the professors have earned themselves and URI an international reputation as pioneers in the field of deep biosphere research. Many students and post doctoral scholars have also been instrumental in the work, which presently is principally funded by the National Science Foundation (NSF), with additional support from other sources. “We combine chemical, geological, biological and physical science

to understand the communities that live beneath the seafloor,” said D’Hondt. As a practical matter, this means taking samples of subsurface sediment, rock and water, then studying its chemical composition to determine how much life it contains and how this life manages to exist. On an earlier expedition, in 2007, the scientists led an international team to the South Pacific, where they collected hundreds of core samples in a vast area known as a gyre. A gyre is the center of an ocean, where there is little wind or other turbulence, leaving the water relatively clear with few nutrients. “Our previous work shows that a huge number of microorganisms lived in the sediment beneath the ocean floor and that they can survive on very little energy or food,” noted Spivack. Now the scientists want to know if microbial communities exist in the very organic-poor sediment extracted from even deeper beneath the seafloor of the central South Pacific, where biological productivity is extremely low in the surface ocean. They also want to determine whether or not microbes in this sediment survive on hydrogen from natural radioactive splitting of water in the sediment, as opposed to organic matter. To answer these questions, in October 2010, D’Hondt, Spivack and Smith went back to the South Pacific Gyre with a team of 30 international scientists on a 65-day expedition. The $10 million journey was funded by the NSF, Japan and several European governments. Spivack called the work “basic science,” but it’s really more than that.

The University of Rhode Island 28