New corals discovered on UK’s highest underwater mountain

New populations of deep-sea corals have been discovered growing on the slopes of the UK’s highest underwater mountain. They could provide an important warning gauge of climate change.

Standing at 1,400 metres above the surrounding seafloor, the Hebrides Terrace Seamount is the UK’s highest underwater mountain. It was recently added to Scotland’s new Marine Protected Areas.

The deep-sea corals were discovered by a robot sub during the first-ever visual survey of the Hebrides Terrace Seamount, an extinct, subsea volcano.

The research team from Heriot Watt University said in a press release that the corals support rich communities of other species and play a critical role in the life history of species that range far beyond the UK’s shores, such as threatened deep-sea skates which lay their eggs on them.

They were surprised to find the corals growing at such depths, in seawater that is less hospitable than shallower water such as Rockall Bank, where some of the best-known cold-water coral reef systems in the world are found.

At the seamount depths, the seawater is naturally more corrosive to coral skeletons. As ever- greater levels of carbon dioxide are released into the atmosphere, the oceans of the world are becoming more acidic.

Therefore the corals discovered during this survey may provide an important warning gauge of climate change, because they are already growing close to their limits. If the water gets any more corrosive as the oceans become more acidic, then the parts of these deep-sea coral reefs that support so many other species will dissolve away.

The knock-on impact of ocean acidification on already-threatened and little known deep-water species, such as the deep-water skate, could be catastrophic.

Because ocean ecosystems are under pressure from ocean acidification and other aspects of global climate change, Marine Protected Areas will become a vital way of conserving fragile ecosystems like those on the Hebrides Terrace Seamount.

The international survey team was led by Professor J Murray Roberts of the School of Life Sciences at Heriot-Watt University, aboard the RRS James Cook.

Speaking about the discoveries, Prof Roberts, Professor of Marine Biology, said: “These were some of the most exciting surveys we’ve ever carried out at sea. We had spent almost a month at sea before we surveyed the Hebrides Terrace Seamount and it was so different from the other sites we examined.

“Now we need to get back to these sites to work out how these corals are able to survive in these harsh conditions.”

Photo credit: Richard Ling/ CC BY-NC-ND 2.0

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