NERC

Into the deep!
The remotely controlled vehicle Isis is providing some of the first images of the sea floor off the coast of Antarctica.

Polar Science from the Deep--Part I

John is a Science contributing correspondent.

It may seem like the Age of Discovery is long gone, but from the perspective of the scientists aboard the U.K. ocean research vessel James Clark Ross, it's just getting started. Earlier this month, the Ross steamed south from Montevideo, Uruguay, ferrying an international team of geologists, oceanographers, and biologists to the Antarctic coast. For the next 2 weeks, they will map the sea floor, vacuum specimens from the ocean bottom, and chase the elusive King Crab. "The deep ocean is one of the least known environments on earth," Sven Thatje, a marine ecologist at the U.K. National Oceanography Centre of the University of Southampton, writes from the ship. The Ross team hopes to change that.

The Ross survey will study the Southern Ocean in greater detail than ever before. Scientists onboard are eager to see whether ancient sea-floor communities known to have flourished before the last Ice Age 20,000 years ago have survived in this area. They are also seeking the king crab, a top predator on the ocean floor. The arthropod is not thought to have scuttled this far south in 15 million years because the water is too cold. If king crabs are spotted in these waters, that will be strong evidence of climate change. Another hope is to find more examples of the recently discovered cold seep" communities, which give clues to how organisms survive extreme environments.

The remotely-operated vehicle (ROV), called Isis, will make a series of dives on the continental shelf and the slope westward of the Antarctic Peninsula. The scientists "fly" the ROV from the ship via a fiber-optic cable that spools out 6.5 kilometers. Besides a cluster of cameras, Isis carries sonar to map the sea floor in 3D. Isis also sports a pair of robotic arms, a suction pump for collecting small specimens, a set of tubes up to 50 centimeters long for gouging sediment cores, and a variety of nets and other gadgets for taking samples.

The first week of the cruise went off without any major glitches, Thatje told ScienceNOW. "Thanks to fair weather and relatively calm seas, by Antarctic standards, we have been able to observe and sample on the deep Antarctic shelf," he says. A 3500-meter dive on 26 January was the deepest dive an ROV has ever made in the Antarctic, says Thatje.

No king crabs have turned up yet, nor deep seep communities, but there is plenty of life to be seen. The largest creature caught so far, a fist-sized stone crab, was wrestled into captivity with the help of Isis's robotic arms and brought up for genetic studies.

The geologists onboard also have reason to be excited. The ROV's sonar has charted dramatic evidence of the ice-driven evolution of Antarctica's coast: rocky debris that must have been delivered to the spot from the continent on icebergs that melted and released their cargo overhead. The mapping has also revealed submarine channels several kilometers wide and "slumped blocks of sediment, meters in diameter and probably several million years old, that slipped down into the channels," says Julian Dowdeswell, director of Cambridge University's Scott Polar Research Institute. The rubble has been lying there in exactly this state for millions of years, writes Dowdeswell, providing fresh evidence that glaciation has been happening on Antarctica for much of its geologic history.

Stay tuned for more reports from Ross. Between now and the end of the cruise on 6 February, ScienceNOW will be bringing you exclusive footage of this high-seas research in action.

Related site

Posted in Earth