Benjamin Peter, edited by Gauthier 7:30 p.m., June 08, 2022
To protect the seabed, the city of Agde has decided to create a marine nature reserve of 300 hectares in 2020. But to preserve tourist and economic activity, an artificial reef entirely made of concrete by 3D printer will be immersed in here at the end of June, to deport the activity of divers to a less fragile environment.
The building installed on the port of Sète in the Hérault is impressive.
105 tons, 7 m high with a dome at the top through which divers can access the interior of the structure.
"We were told that it looked a bit like a temple or a cathedral", laughs Renaud Dupuy de la Grandrive, the director of the marine environment in the city of Agde, at the microphone of Europe 1. "We must imagine diving at a depth of 20 m. We will raise our heads and it will be even more impressive. The divers will be able to circulate in this maze of small niches".
Credits: Benjamin Peter/Europe 1
A nature reserve where no activity is allowed
They noticed that part of the marine protected area of the Agde coast, which extends over 6,000 hectares off the coast of Cape Town, showed some signs of degradation.
So, two years ago, the city decided to create a nature reserve of 300 hectares where no more activity is authorized.
“There were places with natural sites impacted by activity, by boat anchors and by scuba diving activity, because these coral reefs are very fragile,” he explains.
"This famous coralligenous grows by a few millimeters a year and when you break it, you put it up in the air for hundreds of years. We discussed with the diving clubs and we created the Roc de Brescou, where we no longer have the right to do anything except sail", continues Renaud Dupuy.
"But in compensation, we designed this project to make them a village of artificial reefs."
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Reefs made using a gigantic concrete 3D printer
In all, over nearly 1 km², there will be around ten reefs, all designed by the Seaboost company in Montpellier.
They were made by a gigantic concrete 3D printer.
Up close, you can see the layers of low-carbon concrete that create crenellation, which should allow the development of an ecosystem.
"It's all grooved, there will be biodiversity. There will be concretion, so molluscs, algae that will stick to all this", specifies Renaud Dupuy of the Grandrive.
“Also small fish that will live in the small caches that we have created, and larger ones that will circulate, because there will be room to let the current flow,” he explains.
“We expect to have pelagics including rarer species such as grouper which we think have some elements of this reef that may be favorable for its permanent establishment.”
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In a few days, the reef will be embarked on board a huge barge which will take it from the port of Sète to the coast of Cap d'Agde where it will be immersed using a crane, then firmly screwed into the sandy ground.
Divers should be able to explore it this summer.