A CANYON BIGGER THAN COUNTRIES

UCC-LED GROUP OF SCIENTISTS MAPS THE ENORMOUS PORCUPINE BANK CANYON, SOME 320 KILOMETRES WEST OF DINGLE PENINSULA

AN international group of scientists has carried out a research expedition mapping an enormous underwater submarine canyon some 320 kilometres off the coast of Dingle.

The Porcupine Bank Canyon features near-vertical 700-metre cliffs and goes nearly 3,000 metres below sea level in places – the equivalent of ten Eiffel Towers.

The UCC-led group returned earlier this month after using the RV Celtic Explorer and Holland I ROV to image the upper-canyon, mapping a total of 1800 square kilometres of seabed. For further context, Malta is little over 300 square kilometres in size.

“So far from land, this canyon is a natural laboratory from which we feel the pulse of the changing Atlantic,” said Dr Aaron Lim from the UCC school of Biological, Earth and Environmental Sciences, the man who led the expedition.

“Ireland is world-class and, for a small country, we punch above our weight,” he said of the advances in Irish marine technology and scientific workforce.

Submarine canyons cut into continental slopes and continental rises of the oceans, featuring narrow, steep-sided valleys.

The Porcupine Bank Canyon is the most westerly submarine canyon on Ireland’s continental shelf.

The upper reaches of this canyon are a haven for cold-water corals, with reefs and mounds forming a 28-kilometre rim on the canyon’s lip, measuring some 30 metres in height.

A previous expedition, just over three years ago, discovered a new cold-water coral habitat in the area.

This expedition also found much coral debris that had fallen many hundreds of metres.

UCC explained that this latest project will help them learn about how submarine canyons help transport excess carbon dioxide. The ocean’s surface absorbs CO2, and canyons pump it into the deep ocean, meaning it does not return to the atmosphere.

“The corals get their carbon from dead plankton raining down from the ocean surface so, ultimately, from our atmosphere,” Professor Andy Wheeler explained.

“Increasing CO2 concentrations in our atmosphere are causing our extreme weather; oceans absorb this CO2 and canyons are a rapid route for pumping it into the deep ocean, where it is safely stored away.

“We took cores with the ROV, and the sediments reveal that, although the canyon is quiet now, periodically it is a violent place where the seabed gets ripped up and eroded,” he added. Science Foundation of Ireland and Geological Survey Ireland funded this project, with support from the Marine Institute.

The area also has Special Area of Conservation status from the National Parks and Wildlife Service.

Professor Wheeler’s Marine Geology Research Group at UCC will monitor the range of coral habitats to learn more about its habitats.

What the Porcupine Bank Canyon would look like if the sea were drained out.

LEFT: Cold water corals on the rim of the Porcupine Bank Canyon.