August 14, 2013
Zombie Worms And Antarctic Shipwrecks
Brett Smith for redOrbit.com - Your Universe Online
Zombie worms are coming for your bones – but probably only if they end up at the bottom of Antarctic waters.
A new report in the Proceedings of the Royal Society B suggested that if a wooden ship and its crew sank in the Southern Ocean that surrounds Antarctica, any evidence of the crew would decompose long before the ship itself. That's because so-called "zombie worms" - including two newly discovered species - living at the bottom of the sea would devour the crew's bones and because the icy waters also lack a wood-decomposing mollusk commonly found in the rest of the world's oceans.
The results of the study bode well for finding the shipwreck of Ernest Shackleton’s Endurance, which the explorer had to abandon during his ill-fated expedition to cross Antarctica from 1914 to 1917.
"I think it's a reasonable hypothesis to suggest Endurance is still in good condition, certainly based on our experiments and what we know about low microbial rates of degradation in the cold Antarctic deep sea," said study author Adrian Glover in an interview with BBC News.
"Marine archaeologists and historians have long dreamt of finding the wreck and recovering artifacts from Shackleton's expedition,” said Glover, a marine biologist with London’s Natural History Museum. “But I'm interested in how deep-sea ecosystems function and how they recycle large organic inputs. All that oak and pinewood down there would be an amazing experiment in itself, and it would be fascinating to see it."
In the study, a team of European scientists were interested in observing the decomposition activities of organisms found at the bottom of Antarctic waters. To do this, they placed samples of whale bone and wood on platforms that were then lowered to the sea bed.
After 14 month, the team saw that zombie worms, including the two newly discovered species Osedax antarcticus and Osedax deceptionensis, had covered their bone samples. They also observed that the wood samples had remained in pristine condition. This finding supports a previously held theory that said currents around Antarctica prevent wood-eating Xylophaga mollusks from entering the icy waters.
The researchers said their results also suggest that zombie worms are closely related to a group of small mud-dwelling creatures that employ specialist bacteria to help them digest chemicals in oxygen-poor sediments.
"Previous research had suggested that Osedaxhad diverged from groups that inhabited sulphidic hydrothermal vents and cold hydrocarbon seeps," Glover explained. "But as we added in more taxa and more genetic evidence, it implied they are more closely related to these mud-dwelling 'beard' worms. And that makes sense that the ancestors should be a sediment-dweller given what we think about the distribution of whale bones on the sea floor."
Shackleton’s ship is thought to have settled about 10,000 feet below the surface of the Weddell Sea. The UK-based company Blue Water Recoveries is one of many groups formulating a plan to locate the hundred-year-old vessel.
"She was badly holed in the stern by large chunks of ice that broke through the ship's sides below the water line and caused her to flood," said company spokesman David Mearns. "As the damage was too bad to be repairable, Sir Ernest was left with no other option than to abandon ship and set up camps on the ice.”
“While Endurance will be a wreck, I expect to find her hull largely intact,” Mearns said. “She would have suffered additional impact damage when hitting the seabed, but I don't expect this to be too bad."
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