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Study Finds Irish Corals Surviving In Extreme Conditions

A new study shows that Irish cold water corals exist in extreme conditions within the Porcupine Bank Canyon- Irelands largest submarine canyon (3500 m deep). The study shows that corals were able to withstand current speeds greater than 100 cm/s. Corals were observed seen to exist in a range of deep marine settings including at the very edge of a submarine canyon, at a 700 m high near-vertical drop. To do this, scientists had to use deep marine monitoring stations and 3D reconstructions.

New research, led by Dr Aaron Lim (UCC), investigates the extreme conditions at which Irish cold-water corals are growing offshore Ireland. One of the main findings show that the corals can survive at current speeds of up to 114 cm/s, the highest current speed ever recorded in a cold water coral habitat. The study represents the success of recent technological advances in Irish deep marine research and will be used to determine how these vulnerable marine ecosystems may respond to changing environmental conditions.

Marine Institutes Holland 1 ROV at the surface before carrying the monitoring station to 700 m water depth

“These cold-water corals are growing at the very edge of a near-vertical cliff face, in Irelands largest submarine canyon some 850 m below the surface in very intense conditions. They’re quite literally living on the edge” explains Dr Lim.

Cold-water corals help to form deep-water reefs and mounds which can range in height from as little as 10 m to over 100 m. Some coral mounds have existed offshore Ireland for 2.6 million years. The Porcupine Bank Canyon, the area explored during the study shows cold-water corals thriving in a range of deep marine settings. “Some of these habitats were predominantly alive, while others were mostly dead and so the aim of the study was to understand what is driving this?” explains Dr Lim.

One of UCC’s deep marine monitoring stations at the edge of a submarine canyon surrounded by corals (-750 m water depth)

The team use the Marine Institutes Holland 1 Remotely Operated Vehicle (ROV) and research vessel, RV Celtic Explorer, to retrieve data from the coral habitats as well as to deploy deep-water monitoring systems. “The canyon is a strange-place; deep, dark and cold but full of life” explains marine geologist, Luke O’Reilly (UCC). “This submarine canyon is so deep and complex, together with the Marine Institute we developed a monitoring system which could withstand these pressures and conditions for months at a time”, adds O’ Reilly.

The team digitally reconstructed the coral habitats in 3D to understand how deep water currents were influencing them. “Interestingly, we found that while the corals can survive these extreme conditions, it appears that they favour when the current slows down, such as when the tide turns, and this is likely when they feed”, explains Prof Wheeler, Head of School of Biological, Earth and Environmental Sciences at UCC.

The team have recently deployed the monitoring stations for another year with the aim of determining how these corals will respond to these conditions over longer time scales. This research was funded by Science Foundation Ireland and Horizon 2020, with co-funding by the Marine Institute and Geological Survey, Ireland. All shiptime was funded by the Marine Institutes National Shiptime Program. Details of the study can be found here: www.nature.com/articles/s41598-020-76446-y