Underwater Seagrass

Not only are seagrass there in landmass. Under water, the liquid element custody an ecosystem of high biological and ecological value, the Posideonia seagrass.

Are in most oceans of the world except the poles. Their presence in the Mediterranean sea is recent. They came through the Suez Canal, so it knows the Posidonia oceanica as a Lessepsian species.

The generic name of Posidonia includes four families (Zosteraceae, Posidoniaceae, Cymodoceaceae and Hydrocharitaceae) with several species each.


One day, their ancestors emerged from the water to colonize the land. They adapted and evolved. Over time they returned to the sea. This fact it’s very important, because no other known species of flowering plant has experienced.

Communities are shallow (<30m) because they need sunlight for photosynthesis process. Dwelling on sandy or rocky soils and forms a very productive ecosystem (generate oxygen and biomass exported to other ecosystems).

Moreover, there are several epiphytic organisms living on leaves: diatoms, bacteria, red algae, brown algae and filamentous algae. These are consumed by gastropods, bivalves (Pinna nobilis), crustaceans, amphipods, polychaetes (genus Lysidice and Nematonereis mainly) and small fishes (wrasses and porgies). The only animal that has the ability to feed directly from the leaves is the sea urchin Paracentrotus lividus. Besides consolidating the funds and protect the coastline from erosion.

In the Mediterranean are in decline due to overfishing, the action anthropogenic pollution and invasive species such as Caulerpa taxifolia.



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