What Are ‘Posidonia Fruits’ Washing Up on Greek Shores – What Causes This Rare Mediterranean Phenomenon?

At first glance, they might resemble a peculiar green olive… However, their appearance where the waves break confirms that these are rare treasures from the underwater meadows of Posidonia. Recently, locals and scientists have observed Greek shores filling with Posidonia fruits, sparking new research into their nature, behavior, and benefits. According to a post by the Marine Conservation Institute ‘Archipelagos,’ the fruiting of Posidonia in Greece is due to the cleanliness of our seas. These meadows are also crucial for combating climate change, as they can absorb up to 35 times more carbon than tropical forests. They support marine productivity and fishing, hosting over 300 species of algae and more than 1,000 species of marine animals. Unfortunately, due to uncontrolled anchoring, their coverage in the Mediterranean has decreased by at least 34%, making it urgent to plant underwater gardens now that the Posidonia fruits have washed ashore. The institute urges anyone spotting these fruits to take photos with the date and send them for documentation. This rare phenomenon, occurring every few years, provides an opportunity to study and address knowledge gaps about Posidonia reproduction. Researchers previously collected over 12,000 fruits and seeds from various islands in the eastern Aegean for experimental underwater gardens. Given the complexity of such projects, they are rarely attempted globally. Posidonia meadows are vital allies against climate change impacts, absorbing significantly more carbon than tropical forests and supporting marine biodiversity. Their destruction leads to ecosystem loss and re-release of stored blue carbon. With human activity increasingly threatening these resources, Archipelagos emphasizes the need for documented knowledge and practical solutions. If you spot Posidonia fruits on beaches, send photos with details to [email protected].