The Posidonia: The Aquatic Plant That Saves Our Coasts 0 Comments

The Posidonia: The Aquatic Plant That Saves Our Coasts

The Gabbiano Azzurro Hotel & Suites guest perhaps does not know Posidonia, because when he arrives for his holidays, the necessary operation to move the "banquettes" washed up to the beach in winter has already been made, the beach has been cleaned so that one may freely walk on the sand without tripping over the "algae".  

The name Posidonia, accentuating on purpose its great importance in the marine ecosystem, derives from the god of the sea of ​​the ancient Greeks, that bearded Poseidon with the trident.

They are not "algae", those deposits of organic matter in acrid smelling decomposition and which accumulate on the sea coasts due to the wave motion and playing a very important role in the ecosystem. It is to all intents and purposes a plant, with stem, leaves and roots and, to reproduce, it has flowers and fruits, being the adaptation result of the aquatic life of higher plants that 120 million years ago "decided" to move from the mainland to the sea. Deeper waters would preclude photosynthesis, a vital process of the plant, for which Posidonia lives on the sea beds of not deep waters, where the light reaches it and therefore along the coasts. The landscape of the Posidonia prairie that we can encounter, diving or snorkelling, might, at first sight, be dull, while in reality, the prairie acts as a nursery for a myriad of life forms that find shelter there from predators. The prairie is also preferred by the Pinna Nobilis or Noble Pen Shell. The ribbon-shaped leaves can grow up to 1 meter long, green when young and brown when old when detaching from the plant. Deprived of life, they are carried by the currents and washed on the beaches where they form the "banquettes", constituting a protective mound for the beaches and favouring the surface ecosystem.

The fact that it is a resource or waste finds conflicting opinions, but the WWF recommends leaving it where the sea deposits it, stating that "the presence of Posidonia remains on the beach is an indication of high environmental quality, much better than a" blue flag ": municipalities should therefore feel gratified of having it and not do everything instead to remove its presence! The putridness of the leaves is at the basis of the coastal food chains, thus guaranteeing abundant fishing and the strands that beach is a formidable tool to dampen the force of the waves and allow the sand to settle and be retained. However, if it is really considered essential to remove deposits considered excessive, just move them with great care to the edge of the beach, at the foot of the dune, where over time they will be covered by sand and vegetation giving life to a new dune belt; or they can be piled up where they do not bother but at the end of the summer they will be returned to the shore. "

The stranding of Posidonia occurs between the beginning of autumn and the end of winter, favoured by sea currents and wind. In ancient times the coexistence with the "banquettes" was natural and very welcome. Those of us who were “born before" cannot forget the sea scent coming from the coast, so typical, a mix of salty, sparkling, with a smell of seaweed, sulphur and fish leftovers. This bouquet of smells can only be found on an uninhabited beach, perhaps inaccessible to reach due to the "banquette", but which fills your lungs with the scent of salt, iodine and sea. Today the perfect beach, only sand and sea, lacks this olfactory element that accompanies our memories of a past perhaps less "aseptic" but more faithful to nature.

In the past, the inhabitants had in fact learned for generations to use the beached Posidonia in many ways. As both thermal and acoustic insulating material, packaging material and for padding mattresses and pillows ... because we know that one gets used to the smell… Today, scientific research could explore its interesting use in the production of paper, biogas, biodegradable thermoplastic polymers, products for design, and again in the agricultural and livestock sector, in cosmetics and herbal medicine and last but not least in green chemistry.

It is really important to avoid that these precious biomasses mix with non-biodegradable urban waste, are becoming only uncomfortable dirt. How it is essential to publicize the worth of beached Posidonia by fighting the current negative perception in this regard (dirt and stench), sensitizing its usefulness in producing oxygen and trapping carbon dioxide, and protecting the prairies still intact, remedying the damage caused by man with sports boats, coastal trawling and waters muddied by illegal discharges. Never forget that the first act for conservation and protection derives from our individual behaviours.

The "banquettes" protect the coasts from erosion by absorbing the energy of the wave motion that otherwise discharges directly onto the beach, it is one of the primary producers of oxygen, and their disappearance could generate a source of CO2 where there is now a source of oxygen.

The scent I sense is not the sea one; it is the fragrance of the inner part of the sea, the part where I originate from.” (Fabrizio Caramagna)


Written by Daniela Toti

In the photo: wintertime deposits of Posidonia on the seashore - photo by Laura Mor


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