Hidden below the surface of the sea are the so-called “blue forests” or posidonia seagrass “meadows” that abound on the seabed, creating one of the most valuable habitats in the Mediterranean.

“They are virtually everywhere but they are not seaweed. They are ordinary plants. Marine, flowering plants, just like those we have on the shore. Essentially, they have migrated back to the sea from the shore,” WWF biologist Vaggelis Paravas told the Athens-Macedonian News Agency.

As he explained, the meadows of posidonia seagrass constitute a “small miracle” that is not seen in any other place in the world, providing valuable “environmental services” to both humanity and the sea creatures that find refuge there.

“Posidonia is a type of plant that only exists in the Mediterranean. We do not find it in any other place in the world. It is very common but also very important for marine ecosystems,” Paravas said. Not only do these plants protect beaches from erosion, he noted, serving as fertiliser for plants that contain the sand, but also serve as “sinks of blue carbon” that remove carbon dioxide from the atmosphere.

“Posidonia is found in very shallow waters, up to 45 metres deep, precisely because it is a plant that needs sunlight to photosynthesise,” he said, while it is also very sensitive to the cleanliness of the water, pollution and cloudiness. He noted that every square metre of healthy seagrass meadow generates up to 20 litres of oxygen a day, while the “blue forests” store roughly 10 pct of the carbon absorbed by the oceans every year.

“Luckily, in our country we do not have significant pollution in most areas, only in enclosed bays and ports. Therefore, whenever we see long leaves of posidonia we have every reason to swim without fear because the sea is clean and inviting, not just for swimmers but for hundreds of fish and sea creatures,” he added.