THEMES

Posidonia oceanica

Posidonia oceanica

Posidonia oceanica: use and benefits, posidonia on the beach (read and what to do) and description of the marine plant (it is not an alga).

Thereoceanic posidoniait is an endemic marine species of the Mediterranean, which is why it is often called simplyMediterranean posidonia.

Observing thePosidonia meadowsit is possible to spot a large number of marine species that find refuge among its leaves, first of all the Sarpa salpa fish. To find out how to observe the posidonia and the seabed, I invite you to read the guide:like snorkeling.

Posidonia alga

Let's face it right away: if you came to this page by searching the posidonia seaweed, know thatthere oceanic posidoniait's not a'seaweed but oneplant which producesfruitsisflowers just like terrestrial plants. In the photo below you can see its rhizomatous root.

Posidonia oceanica

The so-calledsea ​​olivesconstitute the fruit of this plant. Fruiting occurs between October and December.

Thereoceanic posidoniaform of the enormous underwater meadows which have a considerable ecological importance. In the Mediterranean, theoceanic posidioniacan be a good onebioedicantorethe quality of coastal waters. THEbioindicatorsthey reflect the trend of environmental quality over the longer or shorter period. The reason? Thereposidoniait grows only in clean waters.

This species is found only in the Mediterranean Sea where, due to pollution, it is in decline. It occupies an area of ​​about 3% of the seabed, which corresponds to an area of ​​38,000 square km.

The plant can reach a length of 140 - 150 cm, the lower part of theoceanic posidoniait is lignified and can reach a length of 15 cm. The roots are rhizomes capable of adhering only to soft substrates (sandy, as opposed to algae that stratify and grow on rocky substrates).

The leaves are long, banded and bright green. The leaves turn brown over time: in autumn the leaves turn brown and photosynthetically inactive. During the winter, towards the center of the head, new green leaves are produced which resume photosynthetic activity.

Therefloweringand the production ofsea ​​olivesthey do not always occur in all waters of the Mediterranean. Southern Italy is lucky because in these places fruiting is more common. This fact is not accidental and seems to be related to one of the needs of the plant: the plant would need very high summer temperatures and mild autumn temperatures with waters around 20 ° C.

Unlike theleavesof the plants that emerged, those ofposidoniathey do not have stomata: gas exchanges occur by diffusion and the plant can also absorb nutrients through the leaves (and not only through the rhizomatous root).

Posidonia oceanica: use

The leaves were used, in the past, as building insulation in the construction of roofs. Other uses see it used in the preparation of bedding for livestock and to pack fragile materials (it is for this reason that it was nicknamed theglaziers alga). Before finding more efficient synthetic substitutes, its properties and benefits also made it useful in pharmacology: the leaves were used to prepare anti-inflammatories and products to treat irritations. Even today it is considered a grandmother's remedy, the reason? Presents property antioxidants and antifungals.

Thepropertyof theposidoniaare difficult to list because, even today, this marine plant is the subject of study: over 51 natural substances have been isolated, including phenols, esters, flavonols ...posidoniais being studied for the possibility of extracting substances with appropriate phytochemical methods.

Today a possible use in the agro-technology sector is being studied: as a fertilizer and for the production of biogas.

In practicedo-it-yourself, divers and freedivers use to rub the leaves ofoceanic posidoniaon the glass of the mask to prevent it from misting up.

Posidonia on the beach

In other locations, theposidoniacollection on beach, carried by water currents and now decomposing, can be collected to be used as organic matter for the production of biogas or as a base for composting, a use that is prohibited in Italy.

According to Part IV of the Consolidated Environmental Law, thePosidonia leaves on the beachthey are considered solid waste and must be removed. Unfortunately, law 748/84 prohibits its use for the production of compost (the ban is extended toalgae and aquatic plantsin general).

In Italy, it is not uncommon to seebeachescovered withposidonia, especially in winter and spring, when there are aggregates known asaegagropile (agagropyl), an agglomeration of plant tissues with a rounded shape.


Video: Da rifiuto a risorsa. La nuova vita della Posidonia (July 2021).