Biodiversity, Environment, Headlines, Latin America & the Caribbean

SCIENCE: 350 Degrees Is Bathwater to These Animals

Stephen Leahy

PUERTO AYORA, Galapagos Islands, Ecuador , Jul 5 2007 (IPS) - Marine scientists returned to the Galapagos Islands this week to celebrate a discovery that Charles Darwin never dreamt of: bizarre animals that live in total darkness around active deep-sea volcanoes.

Hydrothermal vent Credit: NASA

Hydrothermal vent Credit: NASA

Thirty years ago, researchers found the first chimney spewing super-hot water – called a hydrothermal vent – 2,500 metres below the surface on the sea floor, with its own thriving animal community. That life could prosper without sunlight or photosynthesis changed forever the very definition of what constitutes "life" on the Earth. And it opened a new window on the possibilities of life elsewhere in the universe.

After all, if a tiny shrimp can live in total darkness, under tonnes of pressure in a toxic chemical soup boiling away at 350 degrees C, why could not life take hold on some distant planetoid where conditions might not be so harsh?

"We knew right away this was the biggest thing in biology in the past century," recalls Fred Grassle of Rutgers University in New Jersey, who mounted the first biological expedition in 1979, two years after the first discovery of hydrothermal vents in the Pacific Ocean about 350 kilometres from the Galapagos Islands.

Grassle is a tall, large man, stooped a little from age and bending to speak to those who are shorter than he. Or perhaps he has been shaped by the many hours crammed into tiny deep sea submersibles like the famous "Alvin", in which the original discovery was made.

"At the time it was thought that the deep oceans were devoid of life and what little life there might be depended on food falling from above," Grassle told a small auditorium filled with local school children in Puerto Ayora as part of public celebration of the 30th anniversary of the vent discovery.


The celebration was spearheaded by ChEss (Biogeography of Deep-Water Chemosynthetic Ecosystems), one of the 14 field programmes of the Census of Marine Life, a global collaboration to document the ocean&#39s life by 2010.

Grassle showed them old slides of skinny, smiling scientists intently working on home-made pieces of equipment so they could explore an environment as exotic and as dangerous as outer space.

While the children are aware the Galapagos Islands are famous for their unique flora and fauna, the deep sea world off the coast of their island home is as fantastic a realm as the moon. And as deep sea scientists like Grassle like to say: "We know more about the surface of the moon than the deep sea."

Located 1,000 kms off the west coast of Ecuador, the Galapagos is also a very active volcanic region, sitting atop a magma hot spot – found largely on one of Earth&#39s dozen or so major tectonic plates -one called the Nazca tectonic plate.

In 1977, the submersible "Alvin" followed a trail of white clamshells to a small collection of fissures in the planet&#39s surface peppered with hydrothermal vents emitting super-heated cloudy water dubbed "black smokers". Although hot enough to melt most metals, the water doesn&#39t boil because of the tremendous pressure at such depths.

Covering an area not much bigger than a baseball diamond, it was thought to be the only one on the planet, Grassle told IPS.

A series of difficult-to-conduct experiments eventually proved that the amazing creatures – tube worms, shrimps and others – living beside these vents use the chemical energy emitted from the vents to survive. The key component in this unique ecological system is chemosynthetic bacteria that often live in symbiosis with the resident animals such as clams and tube worms.

These specialized bacteria oxidise the toxic hydrogen sulfide coming from the vents, providing nutrients for animals higher up the food chain. And in the case of tubeworms, which don&#39t have mouths or stomachs, the bacteria reside inside, providing needed organic compounds in exchange for a comfortable home.

These sulphur-loving bacteria conduct "chemosynthesis," as opposed to the process of photosynthesis that provides life on the rest of the planet, said Grassle. They are ancient, and some scientists speculate that they may have been the first life forms on Earth.

These discoveries sparked an international bloom of deep sea research. Today, about 100 vent sites have been found in the Pacific and Atlantic oceans. They are located along the 40,000-mile-long mountain range that zigzags up and down the middle of the world&#39s ocean basins like a giant zipper, said Christopher German, co-chair of InterRidge, an international nonprofit organisation and ChEss (Biogeography of Deep-Water Chemosynthetic Ecosystems).

The ridge marks the area where the Earth&#39s tectonic plates spread apart and new crust forms from hot lava rising from the mantle, German told IPS.

"Wherever we look along the ridge, we find vents," he said, "and the vents in different regions of the ocean host very different animals," he said.

Roughly 550 vent species have been discovered living in extreme temperature and pressure conditions, and new vent species are discovered at a rate of nearly two per month, said Paul Tyler, co-chair of ChEss.

"Vent science has dominated the field of deep-sea biology in the last 30 years," Tyler said in a statement.

Future vent exploration may be more mineralogical than biological as at least two mining companies are mapping vent sites because of their abundance in gold, copper and other valuable metals. Technological advances make it possible to mine the ocean floor at great depths, although any such operations are complex and costly. And the ecological impacts on the creatures that inhabit the vents could be catastrophic for those at the mine site and those "downstream" from the resulting plumes of sediments that would be dredged up.

Mining may begin as soon as 2009, says Cindy Van Dover, director of Duke University Marine Lab in the United States. Scientists will need to be proactive in developing careful guidelines for companies, including making full ecological assessments of the proposed mining area, she said.

However, the true wealth of hydrothermal vents is their enormous biodiversity, according to Grassle.

"They opened our eyes to the possibilities of where and under what conditions life could thrive," he said. "What I&#39ve learned in the past 30 years is that small organisms like bacteria are under-appreciated."

And that this discovery took place off the coast where Darwin made one of the biggest scientific breakthrough in history "is a nice coincidence", he added with a small smile.

 
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