Alternate Biospheres Under the Sea

In the wake of NASA's press conference about the discovery of arsenic-based life in Mono Lake, California, researchers have reported the discovery of an extensive biological community "living in porous rock deep beneath the seafloor." The ecosystem consists of Chemautotrophic microbes that accumulate energy though chemical reactions independent from UV light.

These microbes were found in deep-ocean sediments and hydrothermal vents where hot water flows out through newly formed volcanic rock in mid-ocean ridges--the lifeforms find habitation within the cooler upper-crustal rock lying under large areas of the seafloor.

Matthew McCarthy's team found these hidden microbes by analyzing carbon isotopes in samples of organic molecules, where they learned that they came from dissolved inorganic carbon in deep seawater. These inorganic carbon pools "consists of carbonate ions formed when carbon dioxide from the atmosphere dissolves in ocean water." Dating the carbon produced a range of 11,800, to 14,400 years old--"that's how long ago the carbon now in those organic molecules was absorbed from the atmosphere into the ocean." What they observed is that the deep biosphere is pumping very old carbon-14 depleted dissolved organic matter into the deep ocean.  This helps us gain a greater understanding of these biogeochemical cycles, and according to McCarthy, the presence of this very old carbon in the mix shows that "the deep-ocean water may actually be turning over more quickly than we thought."

The discovery of life forms within these harsh, "alternate biospheres" will help astrobiologists think even more outside the box when lookin for alien life (like on Jupiter's moon Europa, for example) and will also illuminate what can be occurring behind the scenes of these longer biogeochemical processes here on Earth.

Image: "Deep Blue Sea" by flugdani on Flickr courtesy of Creative Commons Licensing.