Deep-water coral off Irish west coast changing at ‘alarming’ rate

Four-year study by UCC scientists videoed entire mosaic of coral off Kerry coastline

First images of the spectacular deep-waters corals found on the “Theresa” carbonate mound in the Porcupine Seabight, southwest of Ireland. Images: Southampton Oceanographic Centre

First images of the spectacular deep-waters corals found on the “Theresa” carbonate mound in the Porcupine Seabight, southwest of Ireland. Images: Southampton Oceanographic Centre

 

Ireland’s deep-water coral reefs may be changing far more rapidly than previously thought, according to new research by University College Cork (UCC) scientists.

A four-year study by UCC’s marine geology research group has described as “alarming” the rate of change detected on an extensive coral reef on the Porcupine Seabight, some 110km (70 miles) off the Kerry coast.

The study focused on the Belgica Mound province on the Irish Continental margin which is one of the most prolific places of its type on the planet with more than 50 giant coral mounds and 300 smaller coral reefs.

Videography of the entire mosaic tracked an estimated 20 per cent change rate between 2011 and 2015.

The scientist said it was too early to speculate on the precise causes, as the stronger currents could be due to natural variability or due to climate change factors

Lead author of the study Dr Aaron Lim said the change was not detected in the live coral, but in the amount of dead coral and coral rubble.

He said that he believed the overall change may be due to strong currents exposing dead coral buried beneath older parts of the reef.

‘Entirely change’

“Assuming the change continues at this rate, then in 20 years the reef will entirely change,” Dr Lim said.

The scientist said it was too early to speculate on the precise causes, as the stronger currents could be due to natural variability or due to climate change factors.

He said a further project is already underway to determine this, funded by Science Foundation Ireland, the Marine Institute and the Geological Survey of Ireland.

The newly-published research was funded by the Irish Research Council, the Marine Institute and UCC.

As UCC head of geology Prof Andy Wheeler explains, Ireland’s continental margin has extremely favourable conditions for cold-water corals such as lophelia pertusa, formed over millions of years.

Marine-protected areas

Much of the early work here was pioneered by Dr Anthony Grehan of NUI Galway, and a Franco-Irish research expedition recorded some of the first images in 2001.

A further international expedition in 2003 confirmed that at least 60 per cent of European deep-water corals lay off this coastline. The National Parks and Wildlife Service has identified five deep-sea coral zones off our southwest and west coasts as marine-protected areas.

The UCC study, published in the scientific journal Marine Geology, involved the first successful attempt to video a complete deep water reef at a depth of about 1,000m – not once, but twice.

The project engaged the Marine Institute’s remotely operated vehicle, Holland 1, suspended from the State’s research vessel Celtic Explorer.