Coral reefs are usually associated with warm, tropical waters and exotic fish, but not with the cold, deep and dark waters of the North Atlantic where corals were regarded as oddities on the seafloor. It is now known that cold-water coral species also produce reefs, which may rival their tropical cousins in terms of the species richness of associated marine life. Increasing commercial operations in deep waters, and the use of advanced offshore technology have slowly revealed the true extent of Europe’s hidden coral ecosystems. The discovery of extraordinary, 10 km-long chains of the reef-building corals Lophelia pertusa and Madrepora oculata in several hundred metres of water on the Norwegian and Irish Shelves have deeply challenged conventional views. The same coral assemblages are also found associated with large seabed structures in the Porcupine Seabight (offshore Ireland), where they are so abundant that their skeletal remains have, over the millennia, contributed to carbonate mound structures up to 300m high in 700-1200m water depths. The potential of cold-water corals to contribute to the formation of these large seafloor features and their high biological diversity have attracted considerable public attention through reports in numerous national TV and newspaper features.
Coinciding with World Oceans Day, Prof. David van Rooij, Renard Centre of Marine Geology (RCMG), Dept. of Geology and Soil Science, Ghent University, Belgium gave a seminar today in Galway, entitled “Go with the flow: Impact of the Mediterranean Outflow Water (MOW) on NE Atlantic sedimentary processes and ecosystems.” The talk particularly focused on the colonisation of Atlantic margins by cold-water corals since the end of the last Ice Age and how variation in the MOW explains the current distribution pattern of carbonate mounds found, for example, in Irish waters. See also the Lophelia.org website for some more background on cold water corals and carbonate mound provinces.
Special thanks go to Prof. David van Rooij for permission for inclusion of his seminar in this blog.
1) Map of some carbonate mound provinces in North East Atlantic, University of Liverpool.