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New: Agde, capital of tourism and artificial reefs

After the spectacular immersion of low-carbon 3D concrete reefs in the 300-meter band a few months ago, the Hérault town is making a name for itself with the immersion, scheduled for June, of an artificial reef “village” ! It is the largest construction site of this type in the world. The seaside resort, which welcomes more than 4,000 rings and 300,000 tourists each year, including many diving clubs, demonstrates that tourism and environmental protection can be reconciled.

It is artificial that does nature good. It’s not artificial like those plastic flowers that never smell good or those trendy fake grasses that burn your feet in the summer. It is a benevolent artificial. As a hip prosthesis helps humans to walk again without pain, the fish needs a roof to spawn without being immensely disturbed.

The main artificial reef of 110 tons which will be submerged as well as a dozen other smaller modules off Cap d’Agde. Yacine Sersar / City of Agde.

Sandy and muddy bottoms in the Mediterranean

So, we help him a little to build him aquatic HLMs, in a way. 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.

An idea born in Japan in 1954

It was from Japan that the idea came, launched there in 1954, with the aim of creating or expanding the fishing grounds. In twenty-two years, 4.8 million cubic meters of rocks, wreckage of cars or trams, tires have been submerged. A few years later, we submerged “dead bodies” at tire-larigot; private individuals in the Land of the Rising Sun or along the Mediterranean have polluted, without being aware of it, at will with dead weights cobbled together from a chain and a piece of concrete, wood or even… batteries car…!

Experience with car wrecks quickly forgotten in Palavas

Ph. City of Agde.

There were even, in 1967, “specialists” who had not themselves given the best example to follow. An experiment, in particular, had been carried out – then quickly forgotten – in Palavas-les-Flots. On ten hectares, was dumped, by 21 meters to 23 meters deep, carcasses, concrete cubes and pipes, tires. There was a real action plan for the years 1984-1985, particularly in Sète and Saint-Cyprien, capable of being a real barrier to prevent trawlers from fishing in the three-mile zone which is theoretically prohibited to them, unlike the small trades. But hey, nothing green in there, even a counter-productive action in terms of biodiversity, without any prior study or follow-up…!

Artificial 3D concrete reefs will be off Agde

It’s all over. We are no longer in the era of tinkering. We do engineering! 3D concrete! The Montpellier company Seaboost had artificial reefs made in the port of Sète. A dozen blocks, including one of 110 tons, 6.5 meters high and 8 meters by 6 meters base, which waits in the commercial port; the others, including a chaos will arrive by barge. The assembly will be transported two kilometers off Agde at a depth of 21 meters in the first half of June.

Designed to withstand thirty-year storms

Ph. City of Agde.

“This makes it possible to have very designer complex shapes, such as coralligenous, very porous, very elaborate shapes, while saving material. We do not need molds and extra thicknesses for the mold to resist, among other things”, he says. These 3D concrete reefs feature a reinforced concrete slab to “stabilize the reef to be able to cope with a thirty-year swell”. That is to say, an exceptional storm. Which statistically happens every 30 years.

“Used a lot to fry fish”

“Artificial reefs have been used a lot, especially in Japan, to bring fish back, explains Joffrey Capet, project manager at Seaboost. Here 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 tons, with the Marine Protected Area of ​​Agde on funds from Ademe.” (read below). There is not only a desire to increase the number of fish.

Offer a second dive spot with these reefs

The experience aims to share a constraint: the divers are plethora to practice their passion near the famous rock of Brescou off Cap d’Agde, which shelters the not less famous fort of Brescou. These reefs would 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.”

These reefs are part of a larger program

Ph City of Agde.

Director of the marine protected area of ​​Agde classified Natura 2000 (6,152 hectares of which the part of integral reserve measures 310 hectares well beyond the marine area of ​​60 hectares of that of Banyuls), Renaud Dupuy de la Grandrive specifies that “this project is part of a larger program called Recif’lab for which the city of Agde was the national winner of a Pia (Future Investment Program) led by Ademe (Ministry of Ecological Transition) for the recovery of biodiversity. The entire Récif’lab project covers four lots, the first three of which have already been completed”.

Thirty-two and soon 35 smaller reefs already submerged

Ph City of Agde.

Previously, there was the spectacular installation of 32 modules (and soon three more) of 1.5 meters, 1.4 tons each, again made of 3D concrete which offers an unequaled degree of precision. These modules are called XReef, to moor the famous yellow buoys which delimit the beaconing at sea, bathing and navigation areas. These concrete blocks are permanent and protect the bottoms and the rich activity of the Posidonia meadows. They are much greener than their improvised ancestors with tires and chains that scrape the bottom… Their goal is even 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…

Cuttlefish, octopus, conger eel, squid return

The ancillary function of XReef no longer needs to be demonstrated: “We see cuttlefish, octopus, conger eels, squid and lots of fish returning to the coastal strip”, certifies Renaud Dupuy of the Grandrive. From the first week, we had squid eggs! It is real ecological restoration that we are doing in coherence with the protection measures of the Brescou reserve, etc. We have been working on these projects for four years…” Better still: these low-carbon stamped concrete projects are “added value for the management of the maritime environment and the blue economy”, for Renaud Dupuy of Grandrive. They also reinforce (eco)tourism attractiveness!

Access pontoon to eco-friendly Brescou, reedbeds…

These artificial reefs were preceded by a whole ecological restoration program with, in particular, an “ecological” access pontoon leading to the island of Brescou aimed at protecting juvenile fish thanks to a special device; reedbeds (strips) laid under pontoons also serving as fish nurseries then nurseries on the edges of the port quays! In short, in Agde, we try to reconcile tourism and environmental protection.

To acquire this set, the budget is substantial, around 1.5 M€, but most often the city of Agde contributes a modest cost to these operations. For example, on the village of reefs, it contributes €120,000 of the €600,000 of the total cost co-financed mainly by the State and the Occitanie Region. But that is priceless.

Olivier SCHLAMA

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