The Porcupine Bank Canyon is the westernmost submarine canyon on the contiguous Irish margin and exits onto the abyssal plain at 4,000m water depth. The upper canyon is full of cold-water corals that form reefs and mounds which create a rim on the lip of the canyon 30m tall and 28km long. These corals eventually break off and slide down into the canyon where they form an accumulation of coral rubble deeper within the canyon.
Holland 1 ventured deeper into the canyon and found significant accummulations of coral debris that have fallen from hundreds of metres above. Coupled with recent findings on the Irish-Atlantic margin, this discovery shows the advances in both Ireland’s marine technology and scientific workforce, added Dr Lim.
“Ireland is world-class, and for a small country we punch above our weight,” he said.
Professor Andy Wheeler (UCC) explained that corals get their carbon from dead plankton “raining down” from the ocean surface and therefore “ultimately from the atmosphere”.
Increasing CO2 concentrations in our atmosphere are causing extreme weather, he warned. Oceans absorb this CO2 and canyons are a “rapid route for pumping it into the deep ocean where it is safely stored away”, he added.
Sediment cores taken by the ROV reveal that while the canyon is currently quiet, “periodically it can be a violent place where the seabed gets ripped up and eroded.”
The latest mapping data shows a rim feature along the canyon lip at approximately 600m deep.
“When we sent down the ROV we saw that this rim is made of a profusion of cold water corals which appear to extend for miles along the edge of the canyon,” remarked Professor Luis Conti, University of Sao Paulo.