Marine Geosciences Research Group news features

UCC Marine Geology Research Group online articles

Irish deep water coral reefs changing faster than previously thought

New research, led by Dr Aaron Lim (Marine Geology Research Group, UCC), shows that one of Irelands deep water coral reefs is changing at a rate of approx. 20% over 4 years, faster than previously thought. The research, which was published as a number of articles in Marine Geology, represents the first ever successful attempt at imaging an entire deep water reef (approximately 1000 m water depth), not only once, but twice.

“When people hear the word ‘coral’, they normally think shallow, tropical sea’s and sunshine. This couldn’t be further from the truth. In fact, over half the species of coral are cold, deep-water species and many of them can be found in Irish waters between water depths of 600 m and 1000 m” explains Dr Lim.
Ireland’s continental margin has extremely favourable conditions for cold-water corals and this has been the case for millions of years where the corals have been forming giant mounds on the seabed over 100 m in height and several kilometres long. 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 50 giant coral mounds and 300 smaller coral reefs. “The issue is that it is so difficult to image 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 Marine Geology Research Group at UCC use the Irish Marine Institutes Holland 1 Remotley Operated Vehicle (ROV) and research vessel, RV Celtic Explorer, to retrieve images and samples from these deep water reefs. Both in 2011 and 2015, the Holland 1 ROV imaged the entire surface of one of these reefs which revealed for the first time, how these reefs grow at this scale. Initial results showed that the reef was extremely variable and is coping with the contemporary environmental conditions.

Detailed analyses of the reef showed that it changed at a rate of 20% between the years of 2011 and 2015. 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. “Assuming the reef continues to change at this rate, the entire reef surface will be different in 20 years time” explains Dr Lim.

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.