Scientists probe Southern Ocean black smokers for first time

6 February 2010 by Tom Marshall

Scientists on the British research ship RRS James Cook have explored deep-sea volcanic vents in the Southern Ocean for the first time with a remotely-operated vehicle.

Hydrothermal vent

The team have been working a mile and a half deep on the ocean floor to understand the extreme environment around the vents.

Hydrothermal vents, or 'black smokers', are spots on the seabed where volcanic gases and fluid from deep within the Earth force their way through the crust and into the sea. They are dotted along chains of undersea volcanoes where tectonic plates meet. Already the scientists have visited two Antarctic black smoker sites, and they're now on their way to investigate a third possible location.

"Until now we've never visited hydrothermal vents in the Southern Ocean with submersibles" says Professor Paul Tyler, a deep-sea biologist at the National Oceanography Centre, Southampton (NOCS) who has taken part in the research.

The same team first saw the vents using a towed camera during a cruise on the British Antarctic Survey ship RRS James Clark Ross in January 2009. This year they've returned to the East Scotia Ridge, southeast of the South Sandwich Islands, aboard the RRS James Cook.

The ship is carrying Isis, the UK's deep-diving remotely-operated vehicle (ROV), which is equipped with robotic arms to collect samples and high-definition cameras to reveal the world of the vents.

Study sites

The East Scotia Ridge (top box) and the Bransfield Strait

Isis has sampled the fluids gushing from the black smokers, which are hotter than 300°C, and collected animals that live around the vents, bringing them back to the surface for study in specially pressurised chambers. These animals are now being identified, to shed light on the biodiversity of vent ecosystems in the area.

"We can already tell that the vent ecosystem is rich in fauna," Tyler says. "These vents are so isolated that it was a real possibility there wouldn't be anything bigger than microbes living there. But the ROV found a significant hydrothermally-driven community of animals at both sites."

ISIS being deployed

ISIS being deployed

The team plan to announce more about the creatures around the vent once they've studied them further. The animals will be analysed at a molecular level to determine how they are related to animals living at vents in other oceans.

Different species have been found at vents in different oceans, creating a global jigsaw puzzle of marine life that the researchers hope to further complete with their discoveries. The team will also investigate how the species cope with the conditions around the vents, what they eat, and how they reproduce.

Black smokers were only discovered in 1977, when scientists examining the floor of the Pacific Ocean found vents gushing hot mineral-rich fluids into the water. Since then we've learned that these environments support complex, unique ecosystems. But large areas of the world's oceans have yet to be explored for deep-sea vents, particularly towards the poles. Before this project, black smokers had never been found in the Southern Ocean.

Most life on earth depends directly or indirectly on the energy provided by sunlight. Plants exploit that energy through photosynthesis, and most animals either eat plants or other animals. But at deep-sea vents, far beyond the reach of sunlight, the food chain instead starts with microscopic organisms that get their energy from the chemicals in the vent fluid. Other organisms like prawns or shellfish then feed on these microbes.

ISIS being deployed

Expedition scientists launching Isis

The RRS James Cook will return to port in Montevideo in Uruguay on 21 February. In the meantime the ship is moving on to a third site, at the Kemp seamount, a gigantic underwater mountain. Last year the sonar of RRS James Clark Ross discovered a previously-unknown undersea crater here, four miles across and a mile deep. The team now hopes to learn more about what lives in this unexplored feature of the ocean floor.

The current expedition is led by Dr Alex Rogers of the Institute of Zoology in London, and the project team includes researchers from NOCS, the British Antarctic Survey, and the universities of Southampton, Newcastle and Bristol, together with the Woods Hole Oceanographic Institution in the US.