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Exploring unchartered waters

Discovering deep-sea volcanic vents and the marine life they support

Published: 
6 July 2016

 

An increasingly technology-focused society means that demand to extract strategic metals found in the deep sea is rising. But before these can be mined, we need to understand the life that lives there in order to make informed choices about the consequences of our actions.

While the deep sea is still relatively unexplored, two teams of scientists from the National Oceanography Centre (NOCS)/Waterfront Campus Southampton have been the first to discover deep-sea vents and the marine life around them in the Caribbean, the Antarctic and the Indian Ocean. In collaboration with the UK Natural Environment Research Council (NERC), teams led by marine geochemist Dr Doug Connelly, and marine biologists Dr Jon Copley and Professor Paul Tyler have found the world’s most extreme deep-sea volcanic vents and an array of creatures –many of which are new to science and are only just being described.

 

Hot springs

The deep-sea vents in the Cayman Trough, an undersea chasm south of the Cayman Islands, are the world’s deepest known ‘black smoker’ vents, so called for the smoky-looking hot fluids that gush from them. The undersea hot springs, which lie 0.8km deeper than any seen before, may be hotter than 450°C and shoot jets of mineral-laden water more than a kilometre into the ocean above. During an expedition aboard the Royal Research Ship James Cook, Doug and Jon’s team used the NOCS robot submarine Isis to locate and study the vents.

The vents gush hot fluids that are unusually rich in copper, which is of both scientific and economic interest. But the concern with mining minerals from the sea floor is that it would have an effect on the animals that live there. “We don’t yet fully understand what governs the patterns of life down there. If we want to make responsible decisions about how to use the oceans sustainably, it is imperative we get the understanding and knowledge of the habitat,” Jon says.

Teeming with new species

Despite the extreme conditions, the vents are teeming with thousands of a new species of shrimp that has a light-sensing organ on its back which may help it to navigate in the faint glow of deep-sea vents as it lacks normal eyes. The shrimp congregate in hordes (up to 2,000 shrimp per square metre) around the six-metre tall mineral spires of the vents and the team has named the shrimp Rimicaris hybisae, after the deep-sea vehicle that they used to collect them.

Jon explains that finding new species also has benefits for the advancement of technology:

“Some species found at other vents have been used in biotechnology research to develop biomaterials,” he says. “A lot of the microbes that live in these environments have enzymes that work at very high temperatures and these can be used in industry. Soft drink manufacturers already use a high-temperature enzyme to convert starch from potatoes into sugar. And the scaly foot snail, found in the central Indian Ocean, has metal plates on its foot – the unusual structures of which are helping researchers come up with improvements to body armour,” he adds.

Hot vents in a cold ocean

Paul’s research team aboard the RRS James Cook in the chilly waters of the Southern Ocean has also discovered a new set of deep-sea volcanic vents. The team was exploring an area called the ‘Mermaid’s Purse’ along the East Scotia Ridge at 2500m,and Adventure Caldera, a crater-like hole in the sea floor close to the South Sandwich Islands 3km across and 750m at its deepest point.

Using an underwater camera system, Paul’s team saw slender mineral spires three metres tall, with shimmering hot water gushing from their peaks, and gossamer-like white mats of bacteria coating their sides. “This is the first set of hydrothermal vents to be found in Antarctic waters – hot vents in a cold ocean,” says Paul.

“When we caught the first glimpse of the vents, the excitement was almost overwhelming,” says Southampton’s Dr Leigh Marsh, who was on scientific watch at the time of the discovery. Leigh, who is a post doctoral research fellow within Ocean and Earth Science, has since returned to the Caribbean on behalf of the Ocean Exploration Trust, with whom she has also been on a scientific exploration trip to the hydrothermal vent sites of the Galapagos Rift.

Paul explains that like Jon and Doug, his team has been finding new species living around the vents. “Some of them are known to live around hydrothermal vents, like the kiwa crab and the barnacle,” he says. “What is interesting is how the different sexes occur in different parts of the vent. For most of its life, the Kiwa tyleri is trapped within the warm water environment of the vent chimney and is unable to move between vent sites because of the hostile, low temperature. The females that are carrying eggs under their abdomen then move away from the influence of the hydrothermal fluid as it is most likely toxic to the developing embryos.” Despite being discovered in 2011, it has taken until last year to describe the species, which has been named after Paul.

Another discovery was a starfish named Paulasterias tyleri (again, recently described and named after Paul). Unlike most starfish that have five arms, specimens from this family have six or even eight. This extraordinary starfish group is the first to be found in a hydrothermal vent ecosystem and lives between 1,400 and 2,600 metres beneath the surface. Its closest relation lives more than 2000 miles away.

Real threat

The new vents are the fourth set to be discovered around Antarctica in three expeditions since 2009. One of the sites explored, in the South West Indian Ridge in the Indian Ocean, brings into sharp focus the concerns raised by the researchers. China has been granted an exploratory licence by the International Seabed Authority to explore the potential of mining the vents in this area for their rich minerals. The vent field could well be the only known range of some of the newly discovered species.

“There has been an exponential interest in all aspects of deep-sea mining within the last four years, which poses an implied and actual threat to the environment. The deep-sea community is trying to understand the environment, biodiversity, the physiological processes that might be impacted and the resilience of these areas to mining. With that scientific background we could advise UK and international governments who could set responsible guidelines for extraction. At the moment, governance comes a poor third behind exploitation and then science.

Paul states that to a lot of people, the deep sea is out of sight, out of mind. “But it is the last wilderness on earth!” As such, it warrants greater attention, not just from the scientific, but the wider community.

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