Deepest black smokers found in Caribbean

12 April 2010 by Tom Marshall

Scientists have found the deepest known hydrothermal vents, some 5 kilometres down beneath the waves of the Caribbean in the Cayman Trough.

Hydrothermal vent

They used submersibles to probe the vents, finding slender spires of copper and iron ores around the vent, amid jets of water hot enough to melt lead.

"Seeing the world's deepest black smoker vents looming out of the darkness was awe-inspiring," says Dr Jon Copley, a marine biologist at the University of Southampton's School of Ocean and Earth Science who is based at the National Oceanography Centre (NOC) and led the whole research programme. "Superheated water was gushing out of their two-storey high mineral spires, more than three miles beneath the waves."

Autosub6000 launch

Autosub6000 is launched from the RRS James Cook

Hydrothermal vents, also called black smokers, are spots on the seabed where fluid and gases from deep volcanic systems leak up into the seawater. They often host extraordinary communities of plants and animals. These creatures are adapted to high pressure and lightless, scalding conditions.

Unlike most ecosystems on Earth, these communities get their energy not from sunlight, but from the chemical energy found in the fluids pumped out by the vents. The first black smokers were discovered decades ago, but most are in much shallower water.

The submersibles launched from the British research vessel RRS James Cook. They also took samples of the fluids jetting out of the vent, which will now be analysed and compared with samples from other black smokers.

The Cayman Trough is the world's deepest undersea volcanic rift, found on the seabed between the Cayman Islands and Jamaica. At its lowest point, the pressure is equivalent to the weight of a large family car pressing down on every square inch.

The scientists first launched an underwater robot called Autosub6000, which moves around the aquatic environment under its own control. Designed and built by scientists at NOC in Southampton, it carried out a detailed survey of the seabed in the area. They then followed it with another deep-sea vehicle, named HyBIS; this descended under remote control to the vent site Autosub6000 had identified and took samples and pictures. HyBIS was developed by team member Dr Bramley Murton alongside engineering firm Hydro-Lek Ltd.

World's deepest black smoker

The deepest black smoker ever found

"It was like wandering across the surface of another world", says Murton, who controlled HyBIS for the mission. "The rainbow hues of the mineral spires and the fluorescent blues of the microbial mats covering them were like nothing I had ever seen before."

The team will stay in the Caribbean continuing the research until 20 April. They then hope to return to the area over the next year or two with ISIS, the larger of NOC's remotely-operated vehicles, once they can secure ship time to do so. ISIS was recently used to seek out the first black smokers ever found in the Southern Ocean, and has a wider range of abilities than HyBIS. It can take high-resolution images and video of what it finds, and can even bring up animals in specially-pressurised vessels so they can be studied on the surface.

As well as the researchers from Southampton, the expedition also includes scientists from the University of Durham in the UK, from the University of North Carolina Wilmington and the University of Texas in the US, and from Norway's University of Bergen. Colleagues ashore at the Woods Hole Oceanographic Institution and Duke University will help them analyse the data on the newly-discovered vents.