Like every year, in the fall, our beaches are transformed into banks of Posidonia. You know that “seaweed” that many of us complain about. What if we told you that without it, there would be no more beaches at all, would you believe it?
What is Posidonia?
First of all, first revelation: Posidonia is not an algae! Yes we know, it's a shock. It's about a sea plant present in the form of seagrass, endemic to the Mediterranean Sea. Unlike algae, Posidonia has roots and even produces flowers.
Its particularity is its deciduous foliage, which detaches from the plant when it becomes too bulky. Thereby, each fall, Posidonia leaves leave their roots and the sea to wash up on our beaches.
But this plant is not only used as decoration of the seabed. On the contrary, it is full of resources!
Posidonia meadows play a vital role in marine biodiversity.
These serve primarily as refuge for many species animal. The density of their foliage thus offers protection against currents and serves as a nursery for a large part of the marine fauna.
In addition to offering accommodation, food is also provided. Fish such as saup, sea urchins and all herbivorous species in the area relish this plant making it their main source of food.
Wall against erosion
As we said above, each fall, the foliage of the seagrass detach themselves from their roots to reach our beaches. And there again, although dead, Posidonia plays a vital role.
Just as the dead leaves of our forests constitute the basis of life for an entire microcosm, the "benches" of Posidonia formed each fall on our beaches, shelter and protect the coastal fauna and above all, protect our coasts from erosion. Without it, a larger part of our coastline would therefore be washed away each winter by the waves.
In addition, the quantity of beached Posidonia is a good gauge to check that the seagrass beds are in good health and therefore that the water is of good quality. So the more, the better!
Beach lovers, seaside owners, locals and vacationers, we can therefore thank Posidonia for washing up on our beaches every year!
watch out protected species
Within the framework of the law of July 10, 1976 relating to the protection of nature and by the decree of July 19, 1988 relating to the list of protected marine plant species: it is forbidden to destroy, to peddle, offer for sale, sell or buy and use all or part of the plant, alive or dead.
Between its protection and its effectiveness against erosion, we cannot remove the posidonia benches from our beaches. This is why, it is sometimes possible that these benches remain more or less long on them. It's just nature.
Nevertheless, operations to move the Posidonia on the beach or to mix it with new sand are carried out each year in order to give nature a little boost.
Finally, Posidonia is all good!
Refuge for marine and coastal fauna, nursery for marine biodiversity, bulwark against coastal erosion... Posidonia is all good, so it is essential to accept it and protect it.
Especially since not everyone is lucky enough to have it on their coast. In fact, some municipalities are obliged to devise new means of combating the erosion of their coasts each year. And it is expensive. We have the solution that falls to us not from the sky, but from the sea!
Sure, the white sand and our precious pebbles hide for a time of year, but it is to ensure a future for our beaches, our coasts, our city quite simply.
So we say thank you to Posidonia!