Exploring the deep

An Indian scientist was part of an expedition to explore a new world on the ocean floor

Published: Tuesday 30 September 1997

prattipati Shivshankar Rao from the National Institute of Oceanography ( nio ), Goa, has become the first Indian scientist to reach the ocean floor 3,680 metres under the sea level. On invitation from the Rutgers University, usa , Rao joined a three-week long diving cruise expedition into the depths of the mid-Atlantic ridge on board the R V Atlantis along with 23 other scientists mainly from the us , the uk , and Portugal.

The expedition left the Portuguese port of Ponta Delgada in the Azores islands on July 5 and returned to Barbados on July 31. It was sponsored by the us National Science Foundation. On board were biologists, geneticists, and oceanographers eager to map the gene flow and species diversity in the deep sea hydrothermal vent communities.

Rao has been searching for hydrothermal fields and vents also known as deep-sea geysers in the sea near the Andaman Islands in the Indian ocean. He returned from the cruise with 50 kg of suphide samples and hydrothermal minerals, including parts of the chimney vents collected during the entire expedition, where Rao was the main geologist on board. Over the next few months, Rao and the team of nio geologists will analyse the colourful samples.

Sea floor hot springs are responsible for the formation of several metal rich deposits which was first discovered on the East Pacific Rise in 1977. Since then, hydrothermal activity has been found at several locations on the mid-oceanic ridges and on submarine hotspot volcanoes.

Rao joined Bob Vrijenhoek, biologist and the chief of the expedition, for a two-hour descent to the ' tag field', a five sq km area on the ocean floor with a circular sulphide mound that has a diameter of about 200 metres, in the titanium shell dvs Alvin. The Alvin is owned by the us Navy and operated for research. "The Alvin has crouching space for just two scientists and the pilot. It's hard to sit like that for 10 hours, before we begin the ascent. But in the excitement, nothing matters," says the geologist. "I only ate the sandwich and apple they gave each of us on the trip up," he recounts.

" tag was spectacular with a gigantic active black smoker in the centre of a large sulphide mound displaying several dead chimneys and diffusive flows supporting an entirely new ecosystem," was Rao's description. "It was an awesome experience."

The potential commercial value of the hydrothermal minerals is enormous. Some are known to have 50 per cent of copper, zinc and lead deposits. This could be "a resource site as large as those on land", according to Rao. tag 's suphide mound is estimated to contain four million tonnes of metal sulphides, comparable to the volcanic deposits found in Cyprus and Oman, both under commercial exploitation presently.

Before 1977, it was believed that no life was possible at such depths of the ocean, where the sunlight did not penetrate. Now new studies open up possibilities of understanding life on other planets, as also the survival possibilities for life in such highly toxic environments. Biologists are interested in the sulphur-reducing bacteria that float like huge mats in the ocean, and present studies are focusing on the bio-life that thrives there.

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