At first glance, it looks like a pile of smelly seaweed washed up on the beach. Reason why the leash has such a bad image. With the approach of fine weather, some elected officials prefer to have it removed with mechanical devices so as not to scare away holidaymakers. This band of debris deposited by the sea during the tides nevertheless plays an essential role. But also misunderstood. “Many tourists and even locals are unfamiliar with this ecosystem, which is often poorly perceived,” says Laure Blondet, awareness project manager at the French Office for Biodiversity.
Throughout the summer, a major campaign will be carried out in tourist offices of the Iroise marine natural park (Finistère) to “change the look” on the sea line “and make people discover this unknown world. “Because under this pile made up of seaweed, driftwood, shells, cuttlebone or human waste (fishing nets, plastic…), it is teeming with life. “It is home to many decomposing invertebrates such as sea fleas which swarm under this organic matter”, confirms Philippe Le Niliot, deputy director of the Iroise natural park.
A natural brake on erosion
Also harboring small molluscs, insects and crustaceans, the sea line is therefore a wonderful larder for shorebirds such as the sandpiper, the oystercatcher or the great plovers which even make their nest there, hiding their eggs between the dried algae and the pebbles.
Rich in unsuspected biodiversity, the sea line also has other tricks up its sleeve. Acting as an obstacle, it thus dampens the waves and retains the sand, thus making it possible to reinforce the dunes and to fight against the erosion of the coast. “The organic matter produced by the decomposers also promotes the installation of dune vegetation”, continues Laure Blondet, thus inviting to keep the sea line on the beaches. “Only pick up human waste,” she says. But for the rest, we don’t touch anything and we observe. »