February Scientists Find Historic Irish Ship Wrecks Can Act as Artificial Reefs in Irish Waters

Scientists and engineers based at the University of Limerick, NUI Galway and Ulster University, Coleraine have found that ship wrecks off the west coast of Ireland are acting as artificial reefs providing habitat for species more typically found in deeper waters or in canyons. It is thought the wrecks may be acting as refugia leading to improved species resilience to human impacts and climate change by increasing population connectivity.

The recently unveiled Irish National Monuments Service Wreck Viewer lists the locations of more than 4,000 ship wrecks from a total of 18,000 records of potential wrecks in Irish waters giving some indication of the available infrastructure on the seafloor. In recent years, advanced technique scuba divers have started to dive on some of these wrecks located as deep as 150 metres but no deeper wrecks have been surveyed.

Dr Anthony Grehan, School of Natural Sciences from NUI Galway and ocean scientist who made the discovery, said: “Divers report that wrecks are often festooned with corals and other species of epifauna. As such, the wrecks act as artificial reefs and given the quantity of wrecks in Irish waters, may make an important contribution to maintaining coral and other species by providing refugia and stepping stones for further colonisation or restoration of damaged habitats. By surveying these deeper wrecks we wanted to establish whether deeper reef forming corals could survive in shallower water.”

A number of these wrecks lying in deep waters off the west coast of Kerry - beyond the reach of scuba divers - were identified using the Infomar wreck database and investigated for the first time by the team of SFI MaREI engineers and scientists led by Dr. Ger Dooly from the University of Limerick. Profiting from benign weather conditions at this time of year, the survey aboard the national Celtic Explorer (CE19001), successfully located and dove on two large - greater than 100 metres in length – wrecks using a newly commissioned University of Limerick Remotely Operated Vehicle nicknamed Étáin. 

A high definition TV survey of one of the wrecks revealed that intact parts of the ship were indeed colonised by various colourful epifauna: anemones, solitary corals, oysters and brachiopods. The biggest surprise was finding a colony of the coral reef forming Lophelia pertusa, a stony coral species usually found below 500 metres or deeper in Irish waters. The colony was hanging from the apex of two plates where it was likely protected from fishing but still received a plentiful food supply.

Speaking about locating the colony, Dr Anthony Grehan, NUI Galway, said: “This indicates that the species can survive in much shallower waters in Ireland than previously thought with implications for the design and management of marine protected areas and habitat restoration.  Indeed, recent scientific literature addressing ‘ocean sprawl’ points to some of the unexpected positive benefits of long-term structures found on the sea-floor.

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