'Dark energy' -- Life beneath the seafloor: Scientists present recent findings on the subsurface biosphere

So wrote Jules Verne almost 150 years ago in A Journey to the Center of the Earth. Verne probably couldn't have imagined the diversity of life that researchers observe today under the ocean floor.

Scientists affiliated with the National Science Foundation (NSF) Center for Dark Energy Biosphere Investigations (C-DEBI) will discuss recent progress in understanding life beneath the seafloor at the American Geophysical Union (AGU) fall meeting, held in San Francisco from Dec. 3-7, 2012.

Once considered a barren plain dotted with hydrothermal vents, the seafloor and the crust beneath it are humming with microbial life -- with "dark energy," says Katrina Edwards of the University of Southern California, director of C-DEBI.

Seafloor and subseafloor bacteria not only exist, they're more abundant and diverse than previously thought. The bacteria "feed" on the planet's oceanic crust, posing questions about ocean chemistry and the co-evolution of Earth and life.

"We now know that this remote region is teeming with microbes, more so than anyone guessed," says David Garrison, program director in NSF's Division of Ocean Sciences, which funds C-DEBI.

While scientists have estimated that microbes living in deep ocean sediments may represent as much as one-third of Earth's total biomass, the habitable part of the ocean crust may be ten times as great.

Dark environments appeared to offer little energy for sustaining life. But the abundance of microbes in the subseafloor causes scientists to wonder how long life may have thrived there.

Researchers are working to answer such questions as:

What is the nature of subseafloor microbial communities, and what is their role in the alteration of young ocean crust?

Are these communities unique, especially in comparison with seafloor and sedimentary communities?

Where do microbes in the ocean crust come from--sediment, rock, seawater or another source?

C-DEBI-related sessions at AGU include:

InterRidge Session: The Deep Subseafloor Biosphere

Understanding the subseafloor biosphere and its relationship to energy and material fluxes transported by fluid flow has the potential to answer questions about the evolution of life on Earth. This session provides an opportunity to hear results and ideas from various scientific disciplines.

• OS13A. InterRidge Session on: Deep Subseafloor Biosphere I Posters Monday 12/3/12 1:40 p.m. -- 6:00 p.m.; Hall A-C (Moscone South)
• OS22A. InterRidge Session on: Deep Subseafloor Biosphere II Tuesday 12/4/12 10:20 a.m. -- 12:20 p.m.; 3024 (Moscone West)
• OS23B. InterRidge Session on: Deep Subseafloor Biosphere III Tuesday 12/4/12 1:40 p.m. -- 3:40 p.m.; 3024 (Moscone West)
• OS24B. InterRidge Session on: Deep Subseafloor Biosphere IV Tuesday 12/4/12 4:00 p.m. -- 6:00 p.m.; 3024 (Moscone West)

The Deep Biosphere: Recent Progress in Understanding Life in the Deep Subsurface

This interdisciplinary session brings together researchers studying the size, distribution, activity and consequence of a microbial deep biosphere in the Earth's subsurface. Scientists involved in recent ocean drilling program expeditions and other deep biosphere programs will take part.

• B42C. The Deep Biosphere: Recent Progress in Understanding Life in the Deep Subsurface I Thursday 12/6/12 10:20 a.m. -- 12:20 p.m.; 2004 (Moscone West)
• B43G. The Deep Biosphere: Recent Progress in Understanding Life in the Deep Subsurface II Posters Thursday 12/6/12 1:40 p.m. -- 6:00 p.m.; Hall A-C (Moscone South)

InterRidge Session: Fast Moving Research at Slow Spreading Ridges

The range of processes that occurs at slow and ultra-slow spreading ridges has stimulated several multi-national research programs. The findings are relevant for understanding tectonic plate accretion, marine minerals, and chemosynthetic life. With an emphasis on previously overlooked ridge systems in the Northern Hemisphere (Arctic Ridges, Red Sea, Mid-Cayman Rise), and on new findings in the Southern Hemisphere, this session highlights recent results in the geophysical, geological, ocean and life sciences.

• OS11E. InterRidge Session on: Fast Moving Research at Slow Spreading Ridges I Monday 12/3/12 8:00 a.m. -- 10:00 a.m; 3011 (Moscone West)
• OS12A. InterRidge Session on: Fast Moving Research at Slow Spreading Ridges II Monday 12/3/12 10:20 a.m -- 12:20 p.m.; 3011 (Moscone West)
• OS13B. InterRidge Session on: Fast Moving Research at Slow Spreading Ridges III Posters Monday 12/3/12 1:40 p.m -- 6:00 p.m.; Hall A-C (Moscone South)
• OS22B. InterRidge Session on: Fast Moving Research at Slow Spreading Ridges IV Tuesday 12/4/12 10:20 a.m -- 12:20 p.m.; 3022 (Moscone West)