Voyage to the bottom of the sea

THOSE who make tedious jokes about women drivers would be stunned into silence at the skills exhibited by geologist Maria Judge. The NUI Galway (NUIG) graduate recently guided an undersea vehicle that has captured images of the world's deepest known ocean bed volcanic vents, writes LORNA SIGGINS,Marine Correspondent

While Europe’s aviation industry – and the tourism industry with it – ground to a halt as ash from Iceland’s Eyjafjallajökull volcano kept planes out of the skies, Judge and her collaborators were studying photos of the deepest volcanic “black smokers” yet discovered.

Black smokers have nothing whatsoever to do with tobacco. They are seabed vents – hot water springs first discovered in the Pacific 30 years ago – but they have never been found at this depth before.

They release mineral-rich water heated by volcanic activity occurring deep under the seabed. When this superheated water hits cold ocean water, the dissolved minerals precipitate out and billow away like black smoke. They also form mineral chimneys that can grow dozens of metres high.

Judge, who is originally from Sligo, piloted the remotely-controlled undersea vehicle which photographed the vents just over three miles (5,000m) down in the Caribbean Sea’s Cayman trough.

The NUIG graduate is a geologist specialising in rock formations, who has worked as a seismic interpreter, a base metal explorationist and also with the Department of Energy’s petroleum affairs division. She is one of a team of research scientists and engineers from 28 countries who have been working on board the RRS James Cook.

Sea vents of this kind represent one of the most difficult habitats found anywhere on the planet, and yet any vents found are teeming with unusual life forms. The fact that bacteria, algae and other creatures can survive this harsh environment gives scientists confidence that life could form in extreme conditions elsewhere.

The vents “give insights into patterns of marine life around the world, the possibility of life on other planets, and even how life on Earth began”, according to Dr Doug Connelly of Britain’s National Oceanography Centre (NOC) in Southampton, who led the expedition.

The technology deployed included a robot submarine called Autosub6000, developed by NOC engineers in Southampton and pre-programmed with its route before every dive. As Maria Judge explained, it did not have cameras but used sonar to “image” the seabed, flying about 40 metres above the sea floor,

The team then launched another deep-sea vehicle HyBIS to film the deep vents in the Cayman trough for the first time. Maria Judge was one of a team of three operating and maintaining it from the ship.

“HyBIS housed three cameras and a grab bucket capable of collecting samples from the seabed. It could also be fitted with various devices capable of collecting samples of interest to the geologists, chemists, physical oceanographers and biologists,” Judge explains.

“My main tasks were operating the HyBIS cameras (recording the footage and taking the photographs), logging and mapping the areas we were surveying, data management and assisting with servicing the vehicle,” she said.

“I also relieved the main pilot of steering the vehicle at times but was on camera duty when the vents were first discovered.” It was, she said, a “truly exhilarating achievement”.

“On first sight of this incredible, alien environment the room burst into cheers,” Connelly says. “We weren’t watching a documentary, we were filming fluorescent microbial mats and hydrothermal vents billowing black smoke live!”

The expedition team plans to compare the marine life in the trough with information from other deep-sea vents. It also aims to study the chemistry of the hot water gushing from the vents, and the geology of the vent locations on undersea volcanoes.

The voyage on the RRS James Cook finished just over a week ago. The expedition involved researchers from Southampton and Durham universities in Britain, and North Carolina Wilmington and Texas universities in the US, as well as the University of Bergen in Norway.

They have been collaborating with colleagues ashore at the Woods Hole Oceanographic Institution and Duke University in the US.

Further information is on the project website at thesearethevoyages.net

Cayman trough: down home with the ‘extremophiles’

THE CAYMAN trough is the world’s deepest subsea volcanic rift, running across the Caribbean sea floor. Rifts occur at places where the Earth’s crust is pulling apart, allowing the escape of molten rock, such as that of the Eyjafjallajökull volcano in Iceland. Rifts also cause hydrothermal vents on the seabed. These vents discharge mineral-rich hot water heated by volcanic activity.

When the hot water meets the freezing seabed water the minerals billow out and drift away, in some cases looking like black smoke, hence their description as "black smokers". The Cayman vents are special because they are so deep. Its vents lie 5,000m (just over three miles) down, the deepest yet discovered. Pressure at the bottom of the trough is 500 times normal atmospheric pressure: equivalent to the weight of a large family car pushing down on you. Despite the near boiling temperatures and crushing pressures, these deepsea vents teem with life, bacteria, tube worms, shrimp and clams. These are "extremophiles", species adapted to survive in these harsh conditions. DICK AHLSTROM