Scientists now have found "thousands of
times of more bacteria on the seafloor than
in the water above," according to a statement.
The findings were made at two sites, suggesting
that rich microbial life extends across the
ocean floor, says University of Southern California
geomicrobiologist Katrina J. Edwards.
These results, along with a separate discovery
announced very recently existence of life a
mile below the seafloor, have made the scientists
to wonder if life on Earth began along shorelines
or perhaps originated in the planet's marine
Using genetic analysis, Edwards and colleagues
found higher microbial diversity on common,
basalt rocks compared with other marine locations,
such as those found at hydrothermal vents. The
diversity on the seafloor rocks was as rich
as that in common farm soil.
"We now know that there are many more
such microbes than anyone had guessed,"
said David L. Garrison, Director of the National
Science Foundation’s biological oceanography
program. The findings are detailed in the May
29 issue of the journal Nature.
The big question now is where from all these
newfound bacteria get the energy they need to
survive."We scratched our heads about what
was supporting this high level of growth when
the organic carbon content is pretty darn low,"
Edwards said. Perhaps, the researchers figured,
chemical reactions with the rocks themselves
might offer fuel for life. Lab tests also confirmed
The research supports the idea that some bacteria
survive on energy from the crust, a process
that could affect knowledge about the deep-sea
carbon cycle and even the evolution of early
For example, many scientists think shallow
water, not deep water, cradled the planet’s
first life. They reason that the dark carbon-poor
depths appear to offer little energy, and rich
environments like hydrothermal vents are relatively
sparse. But the newfound abundance of seafloor
microbes makes it theoretically possible that
early life thrived—and may be even began—on
"Some might even favor the deep ocean
for the emergence of life since it was a bastion
of stability compared with the surface, which
was constantly being blasted by comets and other
objects," Edwards says.
Much more research needs to be done, however.
Edwards and more than 30 colleagues plan to
take a microbial lab to the seafloor 15,000
feet (4.5 kilometers) below the surface, to
study the bacteria further. They'll drill down
through 109 yards (100 meters) of sediments
and 547 yards (500 meters) of bedrock to study
how the bacteria alter rock and to measure biodiversity
below the seafloor.
This work should shed light on whether the
bacteria evolved from ancestors that floated
down from above or from some as yet unknown
source deep in the crust.
The research was funded by the NSF, NASA Astrobiology
Institute and Western Washington University.
CENTRE Newsletter Vol.6, No 2 Jue