Beebe Vent Field shrimp. (Courtesy of National Oceanography Centre, Southampton (UK)) |
A team of scientists led by marine geochemist Dr. Doug Connelly from the National Oceanography Centre based in Southampton, southern England and marine biologist Dr. Jon Copley based at the nearby University of Southampton has revealed details of the world's deepest known 'black smoker' vents, and the amazing associated array of marine life associated with them. These openings are named as such because of the smoky-looking hot fluids that gush from them.
The deep-sea volcanic vents are located some three miles down in a rift in the Caribbean sea floor. The undersea hot springs, which lie half a mile deeper than any seen before, may be hotter than 840°F (450°C) and are shooting a jet of mineral-laden water over half a mile into the ocean above.
Yet despite these extreme conditions, the vents are teeming with thousands of a new species of shrimp that has a light-sensing organ on its back. And having found yet more 'black smoker' vents on an undersea mountain nearby, the scientists suggest that deep sea vents may be more widespread around the world than previously thought.
During the expedition aboard the Royal Research Ship James Cook, the team used the National Oceanography Centre's robot submarine called Autosub6000 and a deep-diving vehicle, HyBIS, manufactured by the British firm, Hydro-Lek to locate and study the vents in the Cayman Trough, an undersea trench to the south of the Cayman Islands.
The vents, which the team named the Beebe Vent Field after the first scientist to venture into the deep ocean, are gushing hot fluids that are unusually rich in copper, and shooting a jet of mineral-laden water four times higher into the ocean above than other deep-sea vents. "These vents may be one of the few places on the planet where we can study reactions between rocks and 'supercritical' fluids at extreme temperatures and pressures," says Connelly.
Unknown forms of marine life
The team found a new species of pale shrimp congregating in hordes, numbering up to 2,000 shrimp in an area of just over a square yard, around the mineral spires of the vents that stand some 20 feet tall.
Lacking normal eyes, the shrimp instead have a light-sensing organ on their backs, which may help them to navigate in the faint glow of deep-sea vents. The researchers have named the shrimp Rimicaris hybisae, after the deep-sea vehicle that they used to collect them. This Cayman shrimp is related to a species called Rimicaris exoculata, found at other deep-sea vents about 2500 miles away on the Mid-Atlantic Ridge.
Elsewhere at the Beebe Vent Field, the team saw hundreds of white-tentacled anemones lining cracks where warm water seeps from the seabed. "Studying the creatures at these vents, and comparing them with species at other vents around the world will help us to understand how animals disperse and evolve in the deep ocean," says Copley.
The researchers were also surprised to discover black smoker vents on the upper slopes of an undersea mountain called Mount Dent. It rises nearly two miles above the sea floor of the Cayman Trough, but its peak still lies a similar distance beneath the waves. This mountain formed when a vast slab of rock was twisted up out of the ocean floor by the forces that pull the plates of the Earth's crust apart.
The vents on Mount Dent, which the team has named the Von Damm Vent Field to commemorate the life of geochemist Karen Von Damm, are also thronged with the new species of shrimp, along with snake-like fish, and previously unseen species of snail and a flea-like crustacean called an amphipod.
"One of the big mysteries of deep sea vents is how animals are able to disperse from vent field to vent field, crossing the apparently large distances between them," says Copley. "But perhaps there are more 'stepping stones' like these out there than we realized."
Further investigations
The UK expedition that revealed the vents followed a US expedition in November 2009, which detected the plumes of water from deep-sea vents in the Cayman Trough. A second US expedition is currently using a deep-diving remotely operated vehicle to investigate the vents further and the UK team also plans to return to the Cayman Trough in 2013 with Isis, the National Oceanography Centre's deep-diving remotely operated vehicle, which can work at depths of up to nearly four miles.
Reference: Douglas P. Connelly, Jonathan T. Copley, Bramley J. Murton, Kate Stansfield, Paul A. Tyler, Christopher R. German, Cindy L. Van Dover, Diva Amon, Maaten Furlong, Nancy Grindlay, Nicholas Hayman, Veit Hühnerbach, Maria Judge, Tim Le Bas, Stephen McPhail, Alexandra Meier, Ko-ichi Nakamura, Verity Nye, Miles Pebody, Rolf B. Pedersen, Sophie Plouviez, Carla Sands, Roger C. Searle, Peter Stevenson, Sarah Taws, Sally Wilcox. Hydrothermal vent fields and chemosynthetic biota on the world's deepest seafloor spreading centre. Nature Communications, 2012; 3: 620 DOI: 10.1038/ncomms1636