Scientists from University College Cork have discovered plastic at the bottom of a submarine canyon more than 2km deep.
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.
Eight novel monitoring stations called ‘landers’ worth €450,000, deployed by the Marine Institute’s earlier this summer, recorded the speed, temperature and direction of the currents around these habitats.
The stations also trapped samples of the food, sediments and microplastics being deposited around the corals to understand conditions down there and how the corals are coping with changing oceans.
The researchers found plastic in the bottom of the canyon — deep enough to stack ten Eiffel Towers inside — at 2,125m water depth and 320km offshore.
“It’s always sad to see plastic rubbish in these otherwise pristine habitats,” said UCC Professor Andy Wheeler, who has pioneered research on cold-water coral mound offshore Ireland over the past 20 years.
“It’s quite incredible that our plastic waste can get this far out and so deep in the oceans.
“I don’t think people think about this when that dump their rubbish,” he added.
“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.” The Porcupine Bank Canyon is teeming with a whole range of cold-water coral habitats, just on Ireland’s doorstep, according to 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,” he said.
“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 study will provide scientists with an insight into the processes affecting these habitats, the food they are eating and the amount of microplastics impacting on them.
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.
“It’s great that Ireland now has the technological capacity to undertake surveys in the deep seas and answer questions not just for Ireland but also vital to understand our planet’s health,” said Paddy O’Driscoll, superintendent of the ROV Holland I which deployed the monitoring stations.