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Around 7,800 feet under the frigid Southern Ocean, the flash of a remotely operated underwater vehicle captured scenes from a distant undersea ecosystem. Slender chimneys belched plumes of boiling black smoke. A closer look at clusters of white pebbles revealed a writhing mass of countless yeti crabs — a new species. A pale, lone octopus skulked on the ocean floor.

“To sit in the R.O.V. control van and see these sites which no other human had seen up to that point was tremendously exciting,” said Alex Rogers, a professor of conservation biology at Oxford University. “It’s difficult to convey in words, that awe and wonder.”

Dr. Rogers and a diverse group of colleagues recently undertook the first known exploration of hydrothermal vent communities in the East Scotia Ridge, an underwater mountain range formed by plate tectonics, and described their results in the journal PLoS Biology. Deep below the Southern Ocean near Antarctica, hydrothermal vents can reach temperatures of up to 700 degrees Fahrenheit. The unique environment lacks sunlight but is rich in chemicals like hydrogen sulfide.



Discovered in 1977, hydrothermal vents have in some ways changed the way scientists think about life, from microorganisms to animals. The vents occur when cold seawater penetrates the earth’s crust and meets with very hot rocks, resulting in a complex chemical exchange that enriches the water with compounds. When the chemical-laden water exits the seabed, it hits very cold seawater and causes metallic sulfides to precipitate, giving the “smoke” a distinct black hue.

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Before stumbling upon these islands of existence, scientists thought animals occupied a much narrower temperature envelope. What is more, the organisms living in the alien environment thrive on chemical-based food webs rather than on photosynthesis. Given their otherworldly conditions, the vents are considered a potential site of life’s origins, and even hint at a possible source of life on other planets.

“Hydrothermal vents have really extended the environmental scope of life way beyond what we previously considered,” Dr. Rogers said.

Exploring the new system of hydrothermal vents with their four-wheel-drive-size R.O.V., called Isis, the researchers found about two dozen new species, including starfish, barnacles, sea anemones and, potentially, an octopus.

Their new yeti crab boasts a hairy chest rather than hairy claws like its relatives in the Pacific. The scientists think the crabs grow bacteria on the hairs and somehow derive nutrients by harvesting the microbes. The yeti crabs overwhelmingly dominate the ecosystem, with densities up to 600 per square meter (about 55 per square foot). “There were literally heaps and heaps of them,” Dr. Rogers said.

When the researchers work through all their sediment samples, they expect to uncover even more new species.

What the scientists did not find is just as surprising as what they did. “These Antarctic vents look different than any other vent system which has been seen before,” Dr. Rogers said.

Absent were the ubiquitous tube worms of the eastern Pacific vents, or the plentiful shrimps of the Atlantic. Large-shelled predators like crabs and lobsters were also conspicuously missing, and Dr. Rogers hypothesizes that this may be because the physiological mechanisms required for their survival cannot work in the extreme low temperatures of the Southern Ocean.

Some elements of the Antarctic vents, like barnacles and limpets, do seem common to the Atlantic and Pacific vents, a hint that the Southern Ocean may act as a barrier to some vent animals’ dispersal but not others’. The mixed bag of both unique and related organisms suggests that hydrothermal vent ecosystems may be far more complex than originally thought.

Contrary to previous research that there are suggested six distinct biogeographic provinces, or unique ecosystems, Dr. Rogers and his team now propose that a total of 11 separate types of hydrothermal communities exist.

In the space of only an eight-week cruise, Dr. Rogers said, the scientists completely changed their views about the distribution of vent life around the planet. “This shows how little we know about deepwater ecosystems on our planet, which is tremendously exciting as a scientist, but also tremendously worrying,” he said.

Dr. Rogers fears that hydrothermal vents may fall victim to a new form of environmental exploitation. High concentrations of metals like copper and potentially gold and silver billow from the chimneys, a discovery that has caught the interest of mining companies. Within the next year or so, the first hydrothermal vent mining will likely take place off the coast of New Guinea.

“Species around hydrothermal vents are not found anywhere else,” Dr. Rogers said. If mining occurs, he warns, “we may lose animals and systems which we know absolutely nothing about.”

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An earlier version of this post misidentified the journal in which the study on hydrothermal vents appears. It is PLoS Biology, not PLoS ONE.