In the cove of Poulmic, at the end of the harbor of Brest, the bouquets of maërl boule still looked like shimmering hydrangeas a few years ago. Today, these red coralligenous algae – sometimes incorrectly called “Breton coral” – shimmer much less. The 5,000 hectare bench is in bad shape, a good part is degraded or dead, victim of the various human activities in this sector.
Like the reefs of tropical waters, the maërl plays the role of nursery, refuge and breeding ground for many species. In particular, it is home to larvae of scallops, black scallops, seahorses, red mullets and spiders. It slows down coastal erosion and also stores carbon.
Like exotic corals, the maërl boule (Lithophyllum fasciculatum) is fragile, sensitive to the quality of light and the temperature of the water. Its presence is worth to the south of the bay of Finistère to be classified Natura 2000, a European label dedicated to the protection of remarkable habitats of Community interest, such as, on the sea side, the Posidonia meadows in the Mediterranean, or the seagrass, plants with sea flowers.
“About 8,000 years old”
“These calcareous algae are a carpet of biodiversity! Maërl ball grows less than one millimeter per year; in Brittany, it is therefore around 8,000 years old, explains Nazaré Das Neves Bicho, biodiversity project manager for the Armorique regional natural park. The latter is the operator of the Natura 2000 area which extends over 9,000 hectares. This species is also very rare: in addition to Finistère, only four sites are known to date in the west of Ireland. »
In partnership with the French Office for Biodiversity (OFB), the regional park is carrying out restoration actions. In March 2021, the two organizations had professional divers remove nearly 8 tonnes of tires, concrete moorings, old bits, from Poulmic Cove. A large part comes from the activities of shellfish farmers. Changing these practices is one of the objectives.
The regional park team also works to raise awareness among school children, shore fishermen, trawlers… On the Roscanvel peninsula side, boaters are targeted. “We have 850 inhabitants year-round, in summer there are twice as many, so for those who come to visit us, we have to pay attention to our splendid landscapes.assures Jean-François Couret, deputy mayor of Roscanvel, in charge of the sea, very concerned regarding the environment. Maërl, we don’t see it, but we know it’s wonderful! »
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