'Largest Biological Reservoir' Discovered Below Seafloor

Remy Melina livescience.com 14 Jun 10;

The crust located beneath the ocean floor is the site of what could possibly be the Earth's largest biological reservoir, where scientists have discovered marine microbes thriving in harsh environments without any sunlight.

"I think this research is exciting because it offers us a glimpse into a habitat on Earth that we know next to nothing about," said Beth Orcutt, a post-doctoral fellow at Aarhus University in Denmark and the University of Southern California.

Burrowing more than a mile (1.6 kilometers) underwater and drilling through 850 feet (260 meters) of rock, a group of microbiologists has uncovered a little-explored world under the ocean floor. Using a robotic submarine to probe the harsh environment, the scientists were amazed to find a world teaming with microbial life hidden beneath the sediment.

"I hope that the general public will understand that the ocean isn't just a giant pond with a featureless, unexciting bottom," Orcutt said. "The seafloor and sub-seafloor are exciting environments where microbes rule."

Orcutt and her colleagues developed new hole-boring technologies in order to reach the deep-sea life forms. Because they are buried so far below the ocean floor, the microbes dwelling beneath the marine crust receive no light. The team of microbiologists is studying how these organisms are able to survive in such harsh conditions without having to rely on a light source for energy and sustenance.

"If you consider how much ocean crust there is on Earth, and how much of that is hydrologically active, then this environment could be one of the most massive habitats for microbial life on Earth. There may be new species of life and new types of metabolism that we haven't discovered yet," Orcutt said.

Besides uncovering new species, studying these resilient life forms may provide insight into how microorganisms may live on other planets, braving similarly severe conditions, the researchers believe.

"We have to develop sophisticated experiments to try to learn more about these microbial habitats, experiments which will reveal new information about how life survives and thrives on Earth and maybe about how life may exist on other planets," Orcutt said.