Irish cold-water corals can survive in extreme conditions within Ireland’s largest submarine canyon on the Porcupine Bank, a new study has found.

The coral even grows on precipices of high cliffs, and can withstand sea current speed of over 114 centimetres per second, according to the study published today in the science journal Nature.

This is the highest current speed ever recorded in a cold water habitat, according to University College Cork(UCC) scientist Dr Aaron Lim who led the research.

An example of a 3D reconstruction of a cold-water coral habitat from -750 m water depth at the Porcupine Bank Canyon Photo: Aaron Lim

Dr Lim’s team used the Holland 1 remotely operated vehicle (ROV) on the State research ship Celtic Explorer to explore how coral are living in the Porcupine Bank Canyon which is 3,500 metres deep.

The Marine Institue's Holland 1 ROV being deployed from the RV Celtic Explorer as it 'holds' the deep sea monitoring system (attached to the front) before descending to the deep sea Photo: Aaron Lim

He was part of the 2018 expedition which explored and mapped the canyon some 320 km west of Kerry, finding it full of cold-water corals forming reefs and mounds which create a rim on the lip of the canyon.

This latest expedition found coral in a range of deep marine settings.

The scientists had to use deep marine monitoring stations and three-dimensional reconstructions as part of the work. .

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

UCC's deep sea monitoring system at the edge of the submarine canyon where it collects marine environmental data for months at a time

As he explained, cold-water corals help to form deep-water reefs and mounds which can range from as little as ten metres to over 100 m high.

Some coral mounds have existed offshore Ireland for 2.6 million years, he said. 

“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?” Dr Lim said.

UCC marine geologist Luke O’Reilly described the canyon as “a strange-place; deep, dark and cold but full of life”.

“Together with the Marine Institute, we developed a monitoring system which could withstand these pressures and conditions for months at a time,” O’Reilly said.

Prof Andy Wheeler, head of UCC’s school of biological, earth and environmental sciences, noted that the coral can cope with the strong sea currents, but tend to feed when it slows down – such as when the tide turns. 

The team have recently deployed monitoring stations in the canyon to gather information on survival over longer time scales. 

The research was funded by Science Foundation Ireland and Horizon 2020, with co-funding by the Marine Institute and Geological Survey, Ireland. Shiptime was funded by the Marine Institute's National Shiptime Programme.

The study is published here

Marine scientists from University College Cork have discovered plastic at the bottom of a deep submarine canyon while investigating cold-water coral habitats.

UCC’s Marine Geology Research Group has been investigating cold-water coral habitats in the Porcupine Bank Canyon, some 320km due west of Dingle, on a research expedition led by UCC’s Dr Aaron Lim on board the Marine Institute’s RV Celtic Explorer.

The team had recovered eight novel monitoring stations, called ‘landers’, worth €450,000 and deployed between 700m and 2500m water depth by the Marine Institute’s Remotely Operated Vehicle (ROV) Holland 1 earlier this summer.

The monitoring stations record the speed, temperatures and direction of the currents around these habitats as well as trapping samples of the food, sediments and microplastic being deposited around the corals, to understand conditions and how the corals are coping with changing oceans.

The researchers found plastic in the bottom of one canyon at 2,125m water depth — as deep as ten Eiffel Towers stacked on top of one another.

The reach of human plastic waste is now confirmed as this deep, even 320km offshore.

“It’s always sad to see plastic rubbish in these otherwise pristine habitats. It’s quite incredible that our plastic waste can get this far out and so deep in the oceans,” said Professor Andy Wheeler of UCC, who has pioneered research on cold-water coral mounds offshore of Ireland over the past 20 years.

“I don’t think people think about this when that dump their rubbish. We’re also trying to see if microplastics are being fed to the corals from above. We’ve just got the samples; let’s hope we're wrong.”

ROV Holland 1 recovering one of the monitoring stations | Photo: UCC

The Porcupine Bank Canyon is teeming with a whole range of cold-water coral habitats, just on Ireland’s doorstep, says Dr Lim.

“The environment is much more dynamic than we thought, with two of the monitoring stations knocked over by the currents; food supply for the coral is variable but the corals are doing okay.

“Some of these habitats have existed for millions of years and have grown so large they resemble hills made of coral, called coral mounds.

“This is the first time eight of these monitoring stations have been deployed and collected using the ROV Holland 1. It will provide scientists with an insight into the processes affecting these cold-water coral habitats, food sources and the impact of microplastics.”

Dr Lim said Ireland’s cold-water coral reefs are found in the cold, dark ocean at water depths of 600m to 1,000m along our continental margin.

“Not only is this expedition vital for understanding these habitats and our impact upon them, it also acts as a baseline to start monitoring how our deep-water habitats here are changing,” he added.

The team has a research agenda which will see them return to the canyon and other habitats alike for a number of years, to monitor the changes in the environment around these habitats. The monitoring stations will be brought back to UCC for detailed analyses.

This research survey is carried out with the support of the Marine Institute, funded under the Marine Research Programme 2014-2020 by the Government to support and promote the Atlantic Ocean Research Alliance, which facilitates common research and knowledge exchange for us to provide healthy, resilient oceans for our future generations.

The survey has also received funding from Science Foundation Ireland, Geological Survey Ireland and UCC.

#MarineScience - An international team of scientists led by Prof Andy Wheeler of University College Cork have discovered a new habitat for coral in Irish waters – possibly doubling the amount of cold water corals previously thought to exist in the area – while on the Marine Institute's RV Celtic Explorer during the QuERCi survey.

While conducting research on Irish cold water coral reefs, Prof Wheeler investigated a submerged vertical cliff 800m below the sea surface and found it covered in coral.

"The seabed just falls away into a deep chasm. We couldn't wait to take a look down there, using the Holland I remotely-operated vehicle [or ROV] which is equipped with cameras and robotic sampling arms," he said.

Prof Wheeler and his team have been investigating Irish cold water coral reefs for over 15 years. In the deep, cold, dark Atlantic, these corals form reef habitats supporting a diverse and abundant ecosystem.

It was while mapping and inspecting some previously unconfirmed reefs on the edge of the Porcupine Bank Canyon, 300km offshore from Dingle, that the scientists decided to venture further into the canyon itself.

The ROV Holland I was manoeuvred from a 2,100m water depth in the middle of the canyon, up the canyon wall to the coral reefs clustered around the canyon top at 700m water depth. The bottom of the canyon was choked with organic-rich particles flushing down the canyon on the way to the abyssal plain.

"It was like flying the ROV through a snow blizzard," said Dr Chris McGonigle of Ulster University, "but we just pushed up the canyon and it got steeper and steeper and steeper until we faced this vertical cliff face several hundred metres high."

The cliff face, never seen by humans before, was covered in corals and other associated organisms.

"These near vertical habitats hardly feature on maps yet can be hundreds of metres high and extend for tens of kilometres. This is a massive habitat, barely explored, yet full of ocean life", said Dr Agostina Vertino of the University of Milan-Bicocca. "We found many species of coral, sponges, crabs and fish."

Prof Wheeler believes it is "not unfeasible that there is over 100sqkm of coral habitat that was previously unaccounted for."

The coral discovery site has already been designated a Special Area of Conservation due to coral reefs in the vicinity. Yet despite its protection, the international team lead by Prof Wheeler found snagged fishing gear and litter.

"It is a great shame, we are the first people to see this place yet despite of its remoteness there is still evidence of human impacts," he said.

The RV Celtic Explorer is Ireland's state-of-the-art research vessel and has been recently equipped with new seabed mapping sonars giving unprecedented views of the seabed. The ship is also the dive platform for the Holland I ROV.

"The quality of the data that this ship and ROV can now collect is phenomenal," said Dr McGonigle. "We were seeing details on the seabed that a few years ago we could only have dreamed of.

"This increase in data quality will allow us to develop a much greater understanding of the processes controlling the distribution of life in these unique environments."

Congratulating Prof Wheeler and the team on their discoveries, Mick Gillooly, director at the Marine Institute, said "we are delighted to see the recent upgrade of the Celtic Explorer and the ROV Holland's multibeam sonar suite producing such amazing results for this expedition.

"The high resolution images produced are fundamental in helping scientists with their research as well as helping us provide a better understanding our ocean."