Irish shipwrecks being colonised by coral reefs

Ships lying off the Atlantic coastline are being colonised by coral reefs which are normally found in much deeper and colder water.

Colourful anemones colonising the superstructure of the wreck found off the coast of Kerry. Picture: CRIS, University of Limerick

NUI Galway ocean scientist Anthony Grehan, who has pioneered work on cold water coral in Irish waters, has found new evidence of the species within the wreck of a cargo vessel at a depth of 160m.

The WWI wreck located off the Kerry coast had been colonised by anemones, oysters and brachiopods.

However, Mr Grehan was surprised to find evidence of the stony coral species lophelia pertusa which normally thrives at 500m and deeper.

The high definition survey was conducted by a new remotely operated vehicle nicknamed Étáin, developed at the University of Limerick.

The team led by Gerard Dooly of the university’s Centre for Robotics and Intelligent Systems set out to map several large wrecks and a sunken U-boat west of Co Kerry on board the Marine Institute research vessel Celtic Explorer earlier this month.

Colony of the coral reef forming lophelia pertusa, usually found below 500m or deeper in Irish waters. Picture: CRIS, UL

The university’s engineers invited scientists from NUI Galway and Ulster University Coleraine to participate, availing of a period of settled weather.

The team had selected the vessels from a list of more than 4,000 wrecks pinpointed by the State’s seabed mapping programme, Infomar, which is now available on the National Monuments Service ‘wreck viewer’.

“Divers report that wrecks are often festooned with corals and other species of epifauna,” said Mr Grehan.

However, the discovery on the cargo ship confirmed that sunken structures not only act as artificial reefs but “make an important contribution to maintaining coral and other species”.

He described the structures as “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,” said Mr Grehan.

The recently unveiled Irish National Monuments Service Wreck Viewer lists the locations of more than 4,000 wrecks.

The new discovery has implications for implications for the design and management of marine protected areas and habitat restoration, he said.

One of the other wrecks surveyed, the ocean liner SS Canadian, showed a large debris field not visible on the original map, suggesting a “violent impact” with the seabed.

This information was gathered by applying a newly published protocol on high-definition imaging of shipwrecks, developed by Ulster University Coleraine’s centre for maritime archaeology.

Mr Dooly said that close quarter inspection of the sites with a remotely operated vehicle was “technically challenging” and hazardous, due to the presence of abandoned fishing gear. Wrecks are well known as prime spots for commercial fishing.

Mr Dooly said unexploded shells and primers, along with pots and pans scattered on the seafloor near one of the wrecks, reminded the team of the “human misfortune that occurred at the time of the sinking”.

There are 18,000 records of potential wrecks in Irish waters, with more than a quarter located by the Infomar programme, run by the Geological Survey of Ireland and the Marine Institute.

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