By Hirohiko Nakamura From The Asahi Shimbun

Manned submersible circles globe to pursue mysteries of deep-sea life

The water darkens and becomes pitch black as three men in a cramped submersible descend near the British Cayman Islands in the Caribbean Sea.

Then the real stars of the show appear: Creatures thriving in an environment long thought difficult to sustain life.

About 340,000 people watched the world’s first live broadcast of the deep-sea expedition on the “Nico Nico Live” online channel on June 22.

The spectacle from a depth deeper than the 3,776-meter Mount Fuji and where sunlight cannot reach was made possible by the Shinkai 6500, a manned research submersible of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC).

The Shinkai 6500 is currently circling the globe for a string of scientific expeditions that have been joined by scientists from the United States, Britain and other countries.

The voyage is driven not by national ambitions for natural resources, but by an intellectual curiosity to uncover mysteries in vast areas of the planet that have never been explored.

The findings in these extreme environments, such as hydrothermal vents and the crushing pressure in ultra-deep seas, could provide clues on the origins of life itself on Earth.

The Shinkai 6500 can travel as deep as 6,500 meters.

In the dive near the Cayman Islands, the vessel sank at a rate of 40 meters per minute. The submersible can accommodate a crew of only three, comprising one scientist and two pilots.

When the screen was switched to show the image from an inboard camera, viewers saw how Ken Takai, director of the JAMSTEC Extremobiosphere Research Program, shared a cabin–an orb of titanium alloy only 2 meters across–with his two colleagues.

Sea water temperatures are a chilly 1 or 2 degrees more than 2,000 meters beneath the surface.

Curled up in winter suits, the crew members ate lunchboxes before they hit the 5,000-meter-deep seabed at the end of the two-hour descent.

Lights on the submersible revealed hot water spewing from “chimneys,” or column-shaped seabed formations several meters high.

Takai and his colleagues operated two robot arms to catch the small shrimp and sea anemones that crowded the chimneys, and placed them into a sampler. The robot arms also installed a thermometer beside a hydrothermal vent.

Camera imagery of the deep sea was transmitted through purpose-built fiber-optic cables to the seaborne support vessel Yokosuka, and then relayed via satellite for “Nico Nico Live” viewers.

A 10-year international research project that started in 2000 revealed many facts about the distribution and diversity of marine life. But Hiroshi Kitazato, research director of the JAMSTEC Institute of Biogeosciences and leader of the current global journey, said much remains to be learned.

“Most of the seas more than 2,500 meters deep or in the Southern Hemisphere have yet to be surveyed,” Kitazato said. “To fill those gaps, we are focusing on four marine areas, most of them depths in the Southern Hemisphere, during the current journey.”

The Shinkai 6500 left its home port in Yokosuka, Kanagawa Prefecture, on Jan. 5 on board the Yokosuka support vessel. It surveyed Indian Ocean waters off Madagascar between late January and March, the same location where a group of U.S. scientists in 2001 discovered the scaly-foot gastropod, a snail species whose crust and scales are coated with black iron sulfide.

During an expedition in the same area in 2009, the Shinkai 6500 caught white variants of the scaly-foot gastropod that were not coated with iron sulfide. Scientists still cannot explain what caused the difference within the genetically identical species.

The white variants also had tougher scales, raising the question about the role of iron sulfide.

Both white and black specimens were caught during the latest expedition and are being raised aboard the Yokosuka. The scientists plan to investigate the formation process and the role of the coating.

The hot water spouting from the seabed in the area contains high concentrations of hydrogen. The scientists hope to study organisms living near the hydrothermal vents to gain insight into the evolution processes of early life. Incipient life on primordial Earth is believed to have relied on hydrogen for its energy.

The Madagascar expedition was followed by dives in the Atlantic Ocean off Brazil in April and May. It was the first full-scale scientific expedition in that area, home to sea mounts towering more than 5,000 meters in height and currents flowing in from both the Antarctic and North Atlantic oceans.

The scientists confirmed that deep-sea corals, benthos and other creatures inhabited that complex environment. They hope to investigate how habitats vary with depth and geology.

Seabed geology was also a study subject on its own. Scientists held a news conference in Brazil to announce the discovery of granite, a likely remnant of a continent.

Media organizations around the world likened the story to a discovery of Atlantis.

While legend says the Atlantis continent sank 12,000 years ago, the granite is estimated to have submerged in the ocean several tens of millions of years ago. The finding nonetheless provided an occasion for touting the romantic side of the scientific journey.

The online relay took place at the third stop, on the voyage in the Caribbean Sea, where the temperature of the hot water spouts is estimated at 500 degrees. The scientists caught sea anemones, small shrimp and other creatures to study micro-organisms inhabiting the hydrothermal field, with which they live in symbiosis.

Marine creatures used to travel back and forth past this area when the Pacific and Atlantic oceans were connected. But that traffic was blocked when the North and South American continents became connected 3 million years ago.

The scientists plan to study how creatures of Pacific origin evolved in the Atlantic to gain insight into the acclimatization and evolution processes of living organisms.

The Shinkai 6500 returned to Japan on Aug. 2 for recharging operations ahead of another expedition, from October, in the Tonga Trench, the second-deepest area in the world.

“In only 2 percent of all marine areas do depths exceed 6,500 meters,” said Toshio Tsuchiya, a senior official in the JAMSTEC Marine Technology and Engineering Center. “That means the Shinkai 6500 can cover most areas.”

PHOTOS: The Shinkai 6500, a manned research submersible (Provided by the Japan Agency for Marine-Earth Science and Technology)

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