On Sunday, a dive to the ocean floor in a three-man sub called Alvinone of only five deep-sea vehicles in the world able to prowl depths of 4,500 meters (14,764 feet) or greaterfailed to discover the Rose Garden. The garden was last seen in 1990, before civilians had access to the Global Positioning System, which enables very accurate location determination. "Looking for such a small site along the ocean floor is like trying to find a needle in a haystack," said Shank, a veteran of over 30 deep-sea dives.
During this first dive, the team did discover a garden possibly less than one year old with tiny tube worms, mussels and clams all living together. "It was very unusual," Shank said. In vent communities observed thus far, these three creatures are not usually seen together when the garden is young. Within the garden was a dense patch of anemones, their two-inch (five-centimeter) tentacles resembling a translucent shag rug. "The water was filled with debris and tiny worms floating around like a marine snow," Shank said, "and every 30 feet or so we saw bright red shrimpsome up to a foot in length."
Further exploration of the surrounding area during a dive on Monday revealed an old growth communitywith mature tube worms, mussels and clamson the perimeter of the new garden, suggesting that a fresh lava flow ploughed through an older garden. Plants and animals are colonizing the new flow just as they would be on land, said Dan Fornari, a geologist at WHOI, who traveled with Shank on the second dive.
The scientists used a net and Alvin's robotic claw to collect specimens from the garden, which they brought to the surface in a "biobox," also known as the "coffin," where samples remain cold. Among the bounty is a snail that Shank believes might be a new species.
But scientists are perplexed by the absence of the Rose Garden. "During this second trip we really should have seen it," Shank said. "We should have seen signs of a human presence if we were in the right spotsuch as the large steel weights that Alvin leaves behind after each mission." There have been around 25 dives to the Rose Gardenthat's 100 weights that should be scattered in the area, Shank said. "We haven't seen any of them."
"Sometime within the last 12 years the Rose Garden may have been paved over by a fast moving river of lavasomething like you might see on Hawaii," said Fornari. During the next few dives scientists will try to verify whether the garden has been buried.
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