After the spectacular immersion of 3D concrete reefs in the 300 meter strip off Agde, it’s the turn of a “village” of artificial reefs! Objective: to protect wildlife and welcome divers. It is the largest project of this type in the world.

A submerged artificial reef off Cap d'Agde, underwater rocks for fish and divers
Caves and rocks 20 m deep to create a fish village

What do we call these homes full of holes and nooks, cleverly imagined, serving as caches and cabins? Artificial reefs where fish and other marine animals like to frolic in an environment that is sorely lacking in the Mediterranean, with desperately sandy and muddy bottoms, most often devoid of riprap.

“Artificial reefs have been used a lot, especially in Japan, to bring fish back,” explains Joffrey Capet, project manager at Seaboost. “At home too, for the same reasons and because of the sandy bottoms. In Agde, we have set up a unique project in the world with 11 artificial reefs, including one of 110 tonnes, with the Agde Marine Protected Area on bottoms of the Ademe.”

These concrete blocks are permanent and protect the bottoms and the rich activity of the Posidonia meadows, as well as the biodiversity of octopus, squid, lobsters or sea bream. Their goal is even also to make certain species prosper and meet their needs. For this, these modules have been cleverly designed with more or less deep cavities, of different shapes, communicating or not.

“These artificial reefs that we have submerged protect the coast against trawlers coming to fish too close. It also allows fish to reproduce and colonize all of these systems,” explains Gilles D’Ettore, Mayor of Agde.

The artificial rocks in 3D concrete were deposited at a depth of 20 m

Offer a second dive spot with these reefs

The experience aims to share a constraint: many divers practice their passion near the famous rock of Brescou off Cap d’Agde, which is home to the fort of Brescou.

These reefs offer them a second diving spot and relieve tourist pressure by dividing it. “There are many diving clubs on the Brescou site with amateurs and pros. The ecosystem is in danger. These man-made structures will provide a second site. This will make it possible to maintain the presence of the clubs in Brescou.” explains Joffrey Capet, project manager at Seaboost.

“We know very well that this type of reef will work. It is a win-win for dive clubs, with several thousand dives a year and dozens of clubs, and for biodiversity, fauna or flora, we know it will return,” he concludes. Renaud Dupuis de la Granddrive, Marine Environment Director in Agde.

Bastion against the storm

Seaboost of Montpellier built artificial reefs in the port of Sète. About ten blocks, including one weighing 110 tons, 6.5 meters high and with a base size of 8 by 6 meters. The assembly was transported two kilometers from Agde to a depth of 21 meters.

These 3D concrete reefs have a reinforced concrete slab to stabilize the reef so it can handle a thirty year wave. So to speak, an exceptional storm. Which, according to statistics, happens every 30 years.

This project cost the city of Agde €600,000 and was 80% funded by the state and the Occitania region.