Posidonia is the most important plant that grows in the sea

What

Posidonia oceanica plays numerous important ecological roles. First, it acts as a natural filter, improving water quality through its ability to absorb excess pollutants. Furthermore, its dense meadows offer shelter and protection to numerous marine species, serving as a nursery for fish and invertebrates. A one-square-meter patch of Posidonia oceanica can also produce 20 liters of water daily through photosynthesis. oxygen.

Where it is

The presence of Posidonia on the beach is an indicator of the high environmental quality of the coastline. This marine plant plays a key role in the protection and conservation of sandy beaches. The leaves and debris of Posidonia that accumulate on the shoreline form a sort of natural barrier against coastal erosionThe fibrous and resistant structure of Posidonia oceanica holds sand, preventing it from being washed away by the waves and preventing significant losses from the coast. This process of holding the sand in place contributes to the stabilization of beaches, preserving their natural characteristics. The presence of Posidonia oceanica on beaches also has a positive impact on the quality of marine waters. This plant, in fact, helps reduce eutrophication of coastal waters, i.e., the excess of nutrients, preserving the health of marine ecosystems and promoting water clarity.

Today, Posidonia oceanica (Posidonia seagrass) "banquettes," the accumulations often found on beaches, are considered a priority ecosystem by the European Community, which, for this purpose, issued Directive No. 43/92, which provides for the "conservation of natural and semi-natural habitats and of wild flora and fauna." This plant is considered a protected species, as it is included in Annex II of the 1995 Barcelona Convention for the Protection of the Mediterranean Sea from Pollution, ratified in Italy with Law No. 175, dated May 27, 1999. The law therefore requires the protection of Posidonia oceanica and its prevention. Therefore, it is essential to raise awareness of its ecological importance and encourage respectful behavior when using beaches.

Playback

Posidonia oceanica reproduces both sexually and asexually. Sexual reproduction occurs through the formation of hermaphroditic flowers, which have both male and female organs. flowers They sprout between September and October. They produce fruits, called "sea olives," which float with the current until the pericarp ruptures, expelling the seed. Asexual reproduction, however, occurs through stolonization, the multiplication of rhizomes (the plant's stems) by a few centimeters each year.

Posidonia oceanica grows in the Mediterranean Sea. In Italy, it can be found along the coasts of the regions bordering this sea. These include Liguria, Tuscany, Lazio, Campania, Puglia, where it is mainly found on the Tremiti Islands; Sicily, especially in the Marine Protected Area of ​​the Egadi Islands; and Sardinia, particularly in the La Maddalena Archipelago.

Why is Posidonia oceanica in danger?

Unfortunately, in recent decades, Posidonia has undergone a drastic decline due to various threats, such as pollution, unsustainable fishing and the indiscriminate anchoring of vessels. Over the past 15 years, for example, approximately 20.000 hectares of this vital marine plant have been lost in Sardinia. Its protection and conservation are therefore vital to preserving the balance of marine ecosystems and ensuring the health of the oceans.

Research on Posidonia

There are currently several research projects involving Posidonia oceanica. Three of these are: transplantation, conducted by Biosurvey; priming, conducted by the Stazione Zoologica Anton in Naples; and filtering, conducted by the University of Barcelona.

Let's see what it's about:

• The transplantation project, led by the University of Palermo's Biosurvey, focuses on restoring damaged or destroyed Posidonia oceanica meadows. Using advanced techniques, such as transplanting Posidonia oceanica fragments to selected areas using a biodegradable plastic system, researchers seek to promote the growth and regeneration of new meadows. This project aims to restore Posidonia oceanica habitats and preserve their associated biodiversity;
• "Priming" (or "hardening") is a research approach conducted at the Stazione Zoologica Anton in Naples, which involves studying the mechanisms of adaptation of Posidonia oceanica to changing environmental conditions. Scientists seek to understand how Posidonia oceanica can be made more resilient so that it can then transfer this strength to the environment;
• The University of Barcelona is conducting a research project on the filtering action of Posidonia oceanica. This study focuses on the crucial role Posidonia oceanica plays in purifying seawater. According to scientists, Posidonia oceanica, thanks to its clumps of natural fibers, called "felt eggs," is even capable of filtering plastic debris dispersed in the sea along coastal areas. Each kilogram of plant fiber is capable of trapping 1500 pieces of plastic debris.

Cover photo by Frédéric Ducarme – Wikipedia

Read also:

• Sassari Consortium: How Posidonia Oceanica Goes From Waste to Fertilizer and Fuel
• The underwater museum to protect fish