Scientists go out of their depth on exploration of Southern Ocean’s abyss
In the crushing blackness of the ocean looms a mountain range 25 times longer than the Himalayas and all but unexplored.
Among its unseen peaks glowing jets of superheated water surge out of the Earth’s core, supporting intricate webs of life unlike anything else on the planet. Enormous tubeworms, white clams and sightless shrimp gorge on bacteria that have grown with chemical energy rather than light.
Just as islands on the surface revealed the mechanics of life to Charles Darwin 150 years ago, deep-sea vent communities offer biologists a way of understanding the ocean.
Early next year scientists from the National Oceanography Centre in Southampton will investigate the most remote hydrothermal vents yet explored as part of an international, three-year push to understand the mid-ocean ridge.
Using the £36 million research vessel RSS James Cook, which departs from Southampton next week, teams will first explore the vents of the 5,500m (18,000ft) deep East Scotia Ridge in the Southern Ocean, the most southerly ever to be investigated. They will then head to the Caribbean to try to find the deepest.
Running like a livid scar around the world’s oceans, the volcanoes, mountains and valleys of the 40,000 mile (64,400km) mid-ocean ridge cover 32 per cent of the planet’s surface. Less than 10 per cent has been surveyed in any detail, while human eyes have seen a fraction of 1 per cent.
“It is too big a task for any one nation alone,” said Jon Copley, who will be the co-chairman of InterRidge, the co-ordinating programme.
“It is an incredibly exciting time to be involved as there are some remarkable discoveries to be made.The biology of the mid-ocean ridge is like a global jigsaw puzzle. Just as you find lions in Africa and tigers in India, life varies according to where you are.”
Vents in the eastern Pacific Ocean are inhabited by metre-long, red tubeworms and clams the size of dinner plates, while those in the Atlantic swarm with white brittle-stars and blind, 4in shrimp that can sense the glow from a vent using light-sensitive organs on their backs. They live in a world where pressures are around 60 times that inside a lorry tyre.
“We don’t know what we are going to find in the East Scotia Ridge,” Dr Copley said. “If vent life is connected by geology, it should be like the Atlantic. It might be connected by currents, in which case it would be like the Pacific. Or it could be completely different from everything we have seen before.”
In March the James Cook will head to the Cayman Trough in the Caribbean, the deepest known section of oceanic ridge. The chasm, which was the setting for James Cameron’s film The Abyss and reaches depths of 7,686m (25,200ft), is almost entirely unexplored.
The mineral-rich water shooting out of its vents at almost 400C (752F) cools as it mixes with seawater, settling and spreading like a cloud. Chemical sensors towed behind the ship can detect these “clouds”. “Autonomous underwater vehicles” can then be dispatched to survey the area by pinpointing plumes before they spread.
“So far the deepest vent ever discovered is 4,100m (13,450ft). If we find one at 6,000m, life there could be very different,” Dr Copley said.
Japanese researchers will also drive a manned submersible along the Central-Indian Ridge in one of the 20 international expeditions expected to take place annually.
InterRidge will also be talking with the growing number of companies interested in mining the chimneys of copper, zinc, gold and silver left behind by extinct vents.
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