6 January 2012
Oceanographers exploring some of the most remote deep-sea hot springs ever found have discovered what they say is a "riot of life" in a distinct biological zone that no one knew existed.
They said the exploration, which occurred more than 1.6 kilometres down in the ocean just north of Antarctica, uncovered the most strikingly unique assemblage of life forms found in decades, including thousands upon thousands of a species of crab never seen before, as well as new barnacle, anemone, snail and starfish species.
"It's remarkable that we can be in the 21st century and still not know fundamental things about what lives on our planet," said Cindy Van Dover, director of Duke University's marine laboratory, who has been studying life at deep-sea vents for 30 years but was not involved in the discoveries. "This is really exciting because it keeps open the door for even more discovery down the road."
Deep-sea hydrothermal vents are springs that can spew out water at temperatures of more than 400 C. Loaded with chemicals and minerals from the rocks below, the hot water mixes with the much colder seawater in a chemical frenzy that often creates billowing black plumes. Some of the minerals form chimneys around vents that can grow several stories tall.
The Southern Ocean, which surrounds Antarctica, has only recently been a focus of deep-sea exploration. It's particularly difficult to reach, and its waters are treacherous, with storm swells regularly hitting 15 metres in height.
Chris German, a geochemist at the Woods Hole Oceanographic Institution in Massachusetts, was the first to discover deep-sea vents in that area in 1999, after detecting the telltale water plumes, but he was unable to explore them for more than a decade.
In 2010, a group used a remotely operated vehicle to manoeuvre about 2,500 metres down into the icy sea and send high-definition video from the forbidding zone to a British research vessel on the surface.
The team's very first view was the sort that has always driven explorers. Shouts from the scientists watching the monitors quickly drew everyone on board to gaze upon a landscape blanketed by what they quickly realized was a new species of kiwa crab, also known as the yeti because of its hairy body.
"They almost looked like a pile of skulls sitting on the seabed," said the team's leader, Alex Rogers, a deep-sea biologist at Oxford University. "It was an amazing, amazing sight."
The first species of kiwa crab wasn't discovered until 2005, and another was recently announced. But neither of those was found living crunched together in anything like the mobs that Rogers' group found. The researchers also saw thickets of pencil-length barnacles, another new species, growing more densely than similar species the team had seen at other vents. In addition, a new snail species, with a bright-red foot, was crammed a hundred to a square foot.
At the same time, none of the species that dominated every other vent site were there, such as shrimp and tube worms.
Based on genetic analyses, the team believes the vent life they discovered in 2010 is so distinct that it constitutes a cluster of species not found anywhere else. The team published its findings in the journal PLoS Biology.
With further study, the researchers hope to better understand the evolution of life on hydrothermal vents, how those life forms spread around the planet and what determines where they live now.
"Something different happened there," said Tim Shank, a Woods Hole deep-sea biologist who was on the team, "and that tells us about the processes that shape life."
Source: SEAFOOD.COM NEWS [Toronto Star] by Mark Schrope Jan 5, 2012