Arctic Scientists Explore a "Lost" 26-Million-Year-Old Ecosystem

There are few regions on the planet as strange and mysterious as the untouched seafloors beneath the Arctic ice. Over the past several years, scientists have launched expeditions to reveal exotic seafloor life, focusing on an area of hydrothermal vent fields along the Gakkel Ridge, an area that has been almost entirely cut off from other ecosystems for at least 26 million years.

Ocean ridges are like great gashes in the Earth, where hot rock from the Earth's core is forced up.
The Gakkel Ridge is the deepest and most remote portion of the global mid-ocean ridge system. It extends 1,100 miles (1,800 kilometers) from north of Greenland to Siberia, lying about three miles (five kilometers) beneath the Arctic ice cap -an extension of the mid-ocean ridge system which separates the North American tectonic plate from the Eurasian plate.

Scientists are studying the mid-ocean ridge to better understand how the Earth's mantle was formed. The theory is that volcanic eruptions beneath the ocean create new oceanic crust, which then moves away from the ridge in a process, known as seafloor spreading, thought to underlie the movement of continents.

The Gakkel Ridge is the slowest spreading ridge in the world, spreading at a rate of one centimeter (less than half an inch) a year. Ridges in other parts of the mid-ocean range spread up to 18 centimeters (7 inches) a year. Because it is so slow-spreading, scientists expected there would be very little volcanic activity along the Gakkel Ridge.

Up until several recent Arctic expeditions, we have had virtually no idea what’s down there. In 2001 two research icebreakers, the German Polarstern and the US Healy, with several groups of scientists, were sent to the Gakkel Ridge to explore the ridge. Among other discoveries, evidence for hydrothermal vents was found during this expedition. In 2007 the Woods Hole Oceanographic Institution mounted an exploratory expedition called the "Arctic Gakkel Vents Expedition".

“The region has been mostly separated from the Atlantic and Pacific oceans for millions of years, so whatever lives there has since been evolving in relative isolation—much the way animals in Australia did," said Tim Shank, a hydrothermal vent biologist at the Woods Hole Oceanographic Institution (WHOI). "We know that deep-sea Arctic fauna found away from vents are more than 70 percent different from all others around the world. So at hydrothermal vents we are likely to find completely new suites of species with never-before seen adaptations.”

In fact, scientists are expecting to find life forms as different from the rest of the Earth’s biology, as an alien planet could produce. Scientists at the NASA Astrobiology Program believe it is possible that the Gakkel Ridge may harbor life forms and environmental conditions consistent with primordial Earth or even other watery planets.

“The origin of life discussion comes up because the rocks that are exposed on this very slow spreading ridge are not volcanic, but instead come directly from Earth’s mantle,” says geochemist Susan Humphris. “The chemistry is very much like the volcanism that occurred on the primordial Earth. If you are thinking about origins of life, you’d like to have an area that is the closest analog to what was happening on the early Earth.”

Geophysicist Robert Reves-Sohn, who served as chief scientist during a recent expedition says, “Any biological habitats at hydrothermal vent fields along the Gakkel Ridge have been isolated for tens of millions of years. We may have the opportunity to lay eyes on completely new life forms that have been living in the abyss beneath the Arctic ice pack.”

A 30-member research team departed last July from Longyearbyen, Svalbard, for a rare expedition to study Gakkel Ridge,. they spent 40 days aboard the Oden, an 108-meter long icebreaker operated by the Swedish Maritime Administration, which will take the researchers almost to the geographic North Pole.

Since the icy waters are too frigid and dangerous for human explorers to navigate, WHOI researchers built two new autonomous underwater vehicles (AUVs) to aide them on the expedition. The robotic vehicles navigated the underwater world, using cameras and bottom-mapping sonar systems and collect samples for the multi-disciplinary team to study. The team's goal was to discover exotic life forms that may demonstrate incredible adaptations, and even help determine how life originated on Earth.

Posted by Rebecca Sato with Casey Kazan.

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Story Link: http://www.whoi.edu/page.do?pid=7545&tid=282&cid=28811&ct=162

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