Discover underwater flora

A rich and varied world

Underwater life is a treasure trove of diverse flora and fauna. Mediterranean flora includes algae and colorful plants with surprising shapes and appearances. Among them, posidonia stands out, forming vast underwater meadows, called meadows, where magnificent plants flourish.

The limestone sidewalks of refuge algae

Lithophyllum, a red calcareous algae with a pinkish or whitish color, is capable of building ledges along rocks, where waves crash. It forms rock-hard "sidewalks" and shelters a multitude of organisms in its small upright lamellae. The ability of these increasingly rare formations to withstand trampling is still unknown.

A "felted seaweed ball": the Basque beret

The Basque beret, so nicknamed because of its spherical shape, is a green seaweed covered with hairy down. As it grows, it develops depressions that give it the appearance of a Basque beret, reaching up to 40 centimetres in diameter. When young, it measures just five centimetres and captivates with its unique beauty. When diving, it's common to come across dozens of them, like a carpet of large balls, which have been unhooked and are being tossed about by the current.

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Strict cystoseire, a seaweed that braves the waves

Strict cystoseire is a hardy algae that clings firmly to wave-beaten coastal rocks. With its bushy appearance, it forms russet vegetation carpets that undulate on the surface of the sea. This perennial species can live for up to 20 years, providing a refuge for numerous marine organisms.

The sea umbrella, a Mediterranean wonder

The sea umbrella, also known as the acetabularia, grows in groups on well-lit, calm rocky slabs with few currents. It clings by means of small filaments and forms magnificent bouquets up to 6 centimetres high in spring and summer. However, it retreats for the rest of the year, losing its stalk and no longer being visible to the naked eye. This small alga has the particularity of being made up of a single cell, making it a favorite subject of study for geneticists.

Padine peacock tail: a seaweed with cosmetic virtues

Padine is a small fan-shaped algae whose fronds turn white when covered with limestone. It can easily be observed on rocky bottoms exposed to the sun at depths of up to 20 meters, where it can form local mats. It is present during the summer months and disappears in autumn. Padine is used in pharmaceuticals and cosmetics, as it has properties similar to those of young human skin, and is said to have a beneficial protective effect on the epidermis.

Posidonia: guardian of the seabed and shorelines

Although posidonia is not a seaweed but a flowering plant, it plays a central role in underwater life and shoreline preservation. It forms vast herbariums with its roots, rhizomes and long, strap-like leaves. These meadows play an essential role in oxygenating the seabed, providing breeding and feeding grounds for fish, producing organic matter and protecting coastlines from erosion. Some herbaria are over 100,000 years old. Endemic to Mediterranean waters, it is the sea's only flower, blooming from August to November. The name Posidonia comes from Poseidon, the god of the sea in Greek mythology.


Protected beaches thanks to Posidonia

Posidonia, found near beaches in shallow waters, plays a crucial role in protecting coastlines from erosion. Its roots help to stabilize the sandy soils on which it rests, helping to solidify the soil. They form a "bank" when they wash up on beaches in winter, preventing the sand from being washed away by the waves. Preserving the Posidonia on our beaches is therefore in everyone's interest.

Posidonia meadows, cradle of marine life

Posidonia meadows are the true guardians of the marine ecosystem. They serve as spawning grounds and nurseries for numerous underwater species, such as sea urchins, girelles and red mullets. Many juveniles grow up in these dense meadows. These underwater forests are home to over 1,000 species and produce a quantity of oxygen per square metre sometimes greater than that of the Amazon rainforest, earning them the nickname of the "lungs" of the Mediterranean.

Anchors and seagrass beds: a difficult cohabitation

Unfortunately, every summer, boat anchors cause considerable damage to shallow water meadows in the Mediterranean. Heavy anchors rising from the seabed tear up everything in their path, exposing the roots of the Posidonia. These large gaps create an unfavorable environment for Posidonia development, with the appearance, in some cases, of hydrogen sulfide, a compound that limits the plant's development or even causes its disappearance. This damage can take decades or even over a century to heal. Awareness is needed to preserve these precious marine ecosystems.

Admire and protect the underwater flora

Underwater flora is a marvel to be discovered and protected. From seaweed with its astonishing shapes and colors to Posidonia meadows, each species plays a crucial role in the balance of marine ecosystems. By appreciating and preserving these treasures, we help to maintain the beauty and richness of underwater life for future generations.

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