The Underwater Forest of Posidonia oceanica: Recent Developments

In recent years, increasing attention has been given to the conservation of Posidonia oceanica, a vital Mediterranean seagrass species. This policy brief presents a review of the most recent scientific knowledge, along with ongoing efforts to protect and restore its meadows - primarily illustrated through research and experimental work carried out in France. P. oceanica meadows, often called the “underwater forests”, form dense, leafy habitats that support rich marine biodiversity. Like their terrestrial counterparts, they provide shelter and food for numerous species, stabilise coastlines, and sequester significant amounts of carbon, contributing to climate change mitigation. Slow-growing and long-lived some clonal meadows are thousands of years-old, they are also highly vulnerable to human pressures such as anchoring, pollution, and coastal development. Protective measures include anchoring bans, eco-mooring systems, and marine protected area zoning, though enforcement remains uneven across regions. Innovative financing mechanisms, including blue carbon credit schemes, are emerging to support long-term conservation and sustainable local livelihoods.