Irish deep water coral reefs changing faster than previously thought

Research by the Marine Geology Research Group at UCC shows that one of Irelands deep water coral reefs is changing at a rate of approximately twenty percent over four years, faster than previously thought.

New research published by Dr Aaron Lim, Marine Geology Research Group, UCC, explains "the Irish Marine Institutes Holland 1 Remotely Operated Vehicle (ROV) and research vessel, RV Celtic Explorer, were used to retrieve images and samples from these deep water cold water coral reefs not only once, but twice and represents the first ever successful attempt at imaging an entire deep water reef approximately 1000m water depth". 

Ireland's continental margin has extremely favourable conditions for cold-water corals at depths of 600m and 1000m and this has been the case for millions of years where the corals have been forming giant mounds on the seabed that are over 100m in height and several kilometres long. "Over half the species of coral in the world are cold, deep-water species and many of them can be found in Irish waters between water depths of 600 m and 1000 m" explained Dr Lim.

The Belgica Mound Province, on the Irish continental margin is one of the most prolific places on the planet for deep water coral mound development where there are over fifty giant coral mounds and 300 smaller coral reefs. Both in 2011 and 2015, the Holland 1 ROV captured images and footage of the entire surface of one of these reefs, "which has for the first time has provided us the insight into how the reefs grow at this scale.

"Initial results showed that the reef was extremely variable and is coping with the contemporary environmental conditions. However, the issue is that it is so difficult to take images of the deep ocean that we can only get bits of information from these reefs during an expedition," explains Prof Andy Wheeler, Head of Geology, UCC, who has been working on these mounds for 20 years.

The capabilities of the ROV Holland I has enabled the UCC research team to capture images and film at extreme depths of the ocean. "The importance of this technology and having access to the national research vessel has meant that we can get access to what was only a few decades ago inaccessible. We can now provide a detailed analyses of the reef, showing that it changed at a rate of twenty percent in four years, " Dr Lim said.

However, unlike its tropical water counter parts, who are suffering from mass coral bleaching events, the proportion of live coral on this reef did not change. "The change was in fact an increase in the proportion of dead coral and coral rubble areas, which is not the result of live coral dying, but possibly due to the result of strong currents exposing dead coral buried beneath older parts of the reef. Assuming the change continues at this rate, then in twenty years the reef will entirely change," Dr Lim further said.

Dr Lim and Prof Wheeler have just commenced a sizable research project to monitor a range of coral habitats on the Irish Margin with the aim of understanding what is driving these habitats and what makes them change.

This research has been funded by the Irish Research Council, the Irish Marine Institute and University College Cork.

For further information from the corresponding author:
Dr Aaron Lim
Marine Geology Research Group
School of Biological, Earth and Environmental Sciences,
University College Cork
Cork
Email: Aaron.lim@ucc.ie
Web: marinegeology.ucc.ie
The research can be access here :
https://www.sciencedirect.com/science/article/pii/S002532271630281X
https://www.sciencedirect.com/science/article/pii/S0025322717302049