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Deep sea coral connectivity threatened by climate change

A recent study suggests coral populations in the North Atlantic are under threat from climate change. As fragile ecosystems that support an array of marine species could be affected by changes to winter weather conditions, undersea mountains or ‘seamounts’, could hold the key to maintaining ecological links between them. 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.

Researchers have found that corals allow diverse forms of marine life to thrive by building reef structures that provide protection from predators and safe places to reproduce.

But 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. MPAs do not exist in isolation, and to work as intended, they need to be part of interconnected, or coherent, networks, designed to maintain connectivity between populations of marine species. This can be achieved by supporting the movement of migratory species, larval life stages, or simply the circulation of energy and elements across sites.

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.

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.

Dr. Alan Fox, of the University of Edinburgh's School of GeoSciences, who conducted the analysis, said: "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."

Researchers at the University of 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.

Professor Murray Roberts, of the University of Edinburgh's School of GeoSciences and co-ordinator of the ATLAS project, said: "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."