Waters of Ireland and the UK

Cold-water coral ecosystems in Irish and UK waters, particularly those created by framework-building scleractinian corals, are relatively well studied, owing in part to a rich history of geological and oceanographic research in these waters, decades before they were mapped and characterised in terms of their biodiversity. This chapter explores this history and considers the formation and diversity of coral habitats at three scales: (1) small coral ecosystems or mounds (e.g. Darwin Mounds), (2) giant carbonate mounds (e.g. Logachev Mound), and (3) vertical coral ecosystems in submarine canyons (e.g. Whittard Canyon). While corals within each of these ecosystems support a myriad of associated biodiversity and are reliant upon incoming currents delivering a consistent, rich food supply, there are significant differences in underlying oceanography and geology of these ecosystems in the areas where they are found. There is substantial connectivity driven by the dominant water masses between all three main types of coral habitat within Irish and UK waters. Hatton Bank was found to be a critical site for overall habitat connectivity, and Rosemary Bank connects Northern and Western habitats. There are significant current and future threats to all types of Irish and UK coral habitats, ranging from trawling leading to direct habitat loss, to climate pressures including ocean acidification, which could degrade the habitat quality and framework extent (and hence associated biodiversity) of the deeper habitats in particular. As we face these varied threats, effective management strategies become ever more important. While several closures have demonstrated the effectiveness of fishing reduction in preventing further habitat loss, there is now an urgent need to include projected environmental impacts into marine protected area planning to protect these vulnerable marine ecosystems in a rapidly changing ocean.