Porcupine Bank Canyon: An Irish hotspot for deep-sea insights

With its plunging ravine and vibrant biodiversity, the Porcupine Bank Canyon may well be an Irish hotspot for life in the deep ocean, but there’s just one snag: getting to it.

The undersea Canyon starts about 320km off the coast of Kerry and, at its highest point, lies about 700 meters under the Atlantic Ocean. From there it gets even less accessible, swooping rapidly down another 4km or so as it teeters off the edge of the European continental shelf towards the deeper ocean abyss.

Such barriers can be overcome if you know what you are doing, and Professor Andrew Wheeler and his team at University College Cork have the equipment and know-how to monitor this area, which is important for understanding both biodiversity and the mechanics of sea currents.

“The whole canyon is about the size of the lower Shannon, it’s one of the biggest canyons in Irish waters,” explains Professor Wheeler, who is Professor of Geology at UCC and Co-PI for Marine at iCRAG, SFI Research Centre for Applied Geosciences. “This canyon connects the shallow and deeper waters of the ocean, transporting carbon, water and other materials and plays an important role in ocean turnover.”

Professor Wheeler’s research focuses on the upper section of the Canyon, which is home to cold-water coral reefs. “You have this diverse coral reef ecosystem which is like an oasis of life in the deep,” he explains.

The Cork-based researchers send down Ireland’s remote-controlled submarine vehicle to collect images and samples from the Canyon, including core samples of the coral reef from which they can glean clues about historic changes in the area. The team has also installed equipment in the canyon to monitor conditions such as pollutants, organic food supply, water speed, ocean acidity and temperature.

“We are also mapping the coral reefs and measuring aspects of the environment in the canyon to see how the environment relates to the biology,” explains Professor Wheeler. “We are looking at the natural background rate of variation and seasonality in these reefs and examining what drives the changes we see.”

The five-year project will provide important insights about a relatively unseen but important deep-sea habitat, yet despite its inaccessibility, signs of human activity are already leaving their mark: the researchers have seen large pieces of plastic in the Canyon, and they are now seeing if they can detect smaller, microplastics at the site.

“It’s a sad fact that plastic seems to precede us humans in the ocean wherever we go,” says Professor Wheeler. “By measuring these and other aspects of the Canyon though, we will have a foundation for understanding how this important ocean site is changing and this can more generally help to us to protect the deep-sea environment.”