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Deep sea coral faces climate change threat

North Atlantic coral populations – key to supporting a variety of sea life – are under threat from climate change, a study suggests.

Changes to winter weather conditions could threaten the long-term survival of coral in the region, upsetting fragile ecosystems that support an array of marine species, researchers say.

Marine life

Corals allow diverse forms of marine life to thrive by building reef structures that provide protection from predators and safe spaces to reproduce.

The team focused on a species of cold-water coral – known as Lophelia pertusa – which grows in deep waters, creating elaborate reefs that are hotspots of biodiversity.

These populations are maintained by tiny, fragile coral larvae that drift and swim on ocean currents, travelling hundreds of miles between reefs where they attach and begin to grow.

Changing weather

Researchers at Edinburgh used computer models to simulate the migration of larvae across vast stretches of ocean. They did so to predict the effect weather changes could have on the long-term survival of Lophelia pertusa populations in the North Atlantic.

They found that a shift in average winter conditions in western Europe – one of the predicted impacts of climate change – could threaten coral populations.

Ocean currents – affected by changing wind patterns – could drive larvae away from key sites in a new network of marine areas established to help safeguard coral populations, researchers say.

"We can't track larvae in the ocean, but what we know about their behaviour allows us to simulate their epic journeys, predicting which populations are connected and which are isolated. In less well connected coral networks, populations become isolated and cannot support each other, making survival and recovery from damage more difficult," says Dr Alan Fox, School of GeoSciences

Protected areas

The team found Scotland's network of Marine Protected Areas – or MPAs – appears to be weakly connected, making it vulnerable to the effects of climate change.

A coral population on Rosemary Bank seamount, an undersea mountain off Scotland's west coast, is key to maintaining the network.

Corals also thrive on oil and gas platforms in the North Sea and west of Shetland, which may help to bridge a gap in the MPA network between populations in the Atlantic and along the coast of Norway, the team says.

The study is published in the journal Royal Society Open Science. It was carried out in collaboration with Heriot-Watt University through a Daphne Jackson fellowship and as part of the ATLAS project, funded by the European Union's Horizon 2020 research and innovation programme.

"Scotland's seabed plays a unique role as a stepping stone for deep-sea Atlantic species. By teaming up with researchers in Canada and the US, we will expand this work right across the Atlantic Ocean," says Professor Murray Roberts, School of GeoSciences and co-ordinator of the ATLAS project.