Troubled waters

Oil exploration may lead to extinction of deep-water coral in the Atlantic

Published: Monday 15 December 1997

 Down in the sea: corals suppo warm , shallow waters in the tropics are known to support a great diversity of life, including coral -- colonies of polyps cemented together by calcium carbonate or the 'skeletons' of the organisms. But cold, deep waters are also one of the most complex ecosystems and support life forms as diverse as the tropical. The Lophelia coral family is one such exception. Unlike most corals, it inhabits deep waters. This habitat, which has remained undisturbed for centuries, has been threatened in the past decade by deep-water trawling. Now even Lophelia pertusa is threatened by drilling for oil on the Atlantic frontier off the Scottish coast ( New Scientist , Vol 156, No 2100).

The British government's decision in early 1997 to allow oil companies to explore the seas near Scotland has beensharply criticised by environmentalists.

But it is uncertain how exactly oil exploration would damage coral. A group of scientists at the Scottish Association of Marine Science ( sams ) has taken up a three-year study of the deep-water coral to understand, inter alia, the implications of drilling.

It is reasonable to suppose that if the oil companies proceed with their activity without proper assessment of the impact, Lophelia could face extinction. One of the impacts is muddying of the waters. Lophelia grows at a slow rate of 0.5 cm per year, as against the 2 cm-per-year growth of tropical coral. Deposits of sediments on the coral could inhibit its growth or kill it. Additionally, heavy metals in grease, used as a lubricant in drilling, could also prove fatally toxic.

According to Murray Roberts of sams , the threat to Lophelia assumes greater importance since, like other corals, it supports a variety of life forms, which will also die if it is affected. As yet, little is known about the coral.

A photographic survey carried out in 1996 by the Southampton Oceanography Centre, uk , revealed that there were few large coral colonies off the Scottish coast. Only one colony, 20 cm in diameter, could be located in a 60,000 square metre (sq m) stretch of the seabed. However, the survey was limited. While there may be no 'Scottish Great Barrier Reef', the coral can be found scattered along the edge of the continental shelf in isolated patches up to 10 m in diameter. Off the Norwegian coast, there are banks up to 30 m high, 100 m wide and hundreds of metre long. The sams study will add to scientists' knowledge of the coral and help in conservation of marine life.

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