A team of scientists from Ireland have laid artificial reefs deep underwater to help coral recover after decades of being pulverised by bottom-trawling fishing ships.
The team from University of Galway, with colleagues from France, placed 23 of the structures on the seabed of the Porcupine Bank 200km off the Kerry coast, and in the Bay of Biscay off France.
Each 600kg reef is 3D-printed in Italy using concrete and volcanic rock to create irregular shapes like naturally forming reefs.
Nooks and crannies are part of the design to enable coral to take hold and provide shelter for fish and other sea life.
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Dr Anthony Grehan, a deep-sea ecologist and co-leader of the mission, said the aim was to speed up restoration of the vital marine habitats.
“Because these corals grow by only a few millimetres each year, natural recovery of lost reefs can take decades to centuries,” he said.
“With this project, we are testing whether we can actively accelerate that recovery by creating new starter structures for corals to grow on.”
The reefs were laid over several weeks in August in waters 1,000 metres deep – a first for coral recovery efforts which normally focus on shallow waters.
Each reef was lowered to the seabed secured to lines that also carried cables so signals could be sent to the equipment to record the progress, capture the location and unhook from the structure.
A kilometre down is too deep for divers without manned submersibles, so ensuring the reefs can be found again is essential.
“We have the GPS co-ordinates to within a few metres, so we’ll be able to go back and inspect them remotely,” said Grehan.
“We were able to locate some reefs laid last year in the Bay of Biscay and what we found was very encouraging.”
Cold-water and deep-water coral is less well-known than its warm-water cousins, but it is believed there was once an entire coral belt running between Ireland and France.
Coral can form extensive reefs over centuries of slow growth but they have been decimated in places by deep-sea commercial fishing.
“I liken it to cutting down a giant redwood forest in California,” said Grehan. “You could replant but it won’t be the same forest. It would take hundreds of years to get back to something resembling what it was.”
The EU-backed Redress (Restoration of deep-sea habitats to rebuild European Seas) expedition is part of a wider project between University of Galway, the French Institute for Ocean Science and the Sorbonne University in France.
Grehan believes there is scope for it to inspire similar efforts in many other places.
“We’re still at the beginning of this. This was a feasibility study to see can we do it, and we can,” he said.
Coral is being lost worldwide as seas heat and storms intensify with climate change while fishing, oil and gas extraction, seabed mining and cable-laying inflict more damage.
“A lot of different approaches to restoration are being tried,” said Grehan. “One of our partners in the UK harvest corals that have grown on oil rigs in the North Sea that are being removed. They rehabilitate them and bring them back to sea.”
He said every effort should be made to save and restore coral reefs.
“They are an oasis in the deep sea. They provide this very complex microhabitat for lots of different species.
“You find fish nurseries in them and they help to sequester carbon. They may also have pharmaceutical uses.
“So they are very important quite apart from the fact that they are spectacular examples of our natural history.”
