BENEATH THE TURQUOISE BLUE WATERS OF THE MEDITERRANEAN LIES ONE OF THE PLANET’S MOST VITAL YET OVERLOOKED UNDERWATER FOREST: THE PROTECTED POSIDONIA OCEANICA SEAGRASS MEADOWS.
THESE ANCIENT UNDERWATER PLANTS ARE CRUCIAL TO MARINE BIODIVERSITY, CLIMATE STABILITY, AND COASTAL ECONOMIES, HOWEVER THEY ARE INCREASINGLY DESTROYED DUE TO HUMAN ACTIVITY.
For two decades, the Archipelagos Institute of Marine Conservation has been leading efforts to study, protect, and restore these precioushabitats in the Greek seas, before it’s too late…
What is Posidonia oceanica?
Posidonia oceanica is a seagrass species endemic to the Mediterranean Sea. It is among the oldest living organisms on Earth, with some meadows estimated to be over 10,000 years old. Their deep roots and rhizomes help prevent beach and coastal erosion, stabilizing shorelines. They are an invaluable natural ally in tackling the effects of climate change. Impressively they can absorb carbon dioxide at a rate of up to 35 times greater than tropical rainforests. Each square meter of Posidonia can produce up to 20 liters of oxygen per day, while it is a vital habitat for over 1,000 species of marine animals and 300 species of marine plants. In fact, more than half of the oxygen we breathe comes from our seas, while seagrasses like Posidonia play a major role in that.
The Archipelagos Institute studies how much carbon these meadows can store in different areas and depths and how we can maximize their potential to help offset our global emissions. The disappearance of seagrass meadows are also an indicator of the increasing temperatures and the detrimental impacts of climate change.
Despite the critical role they play, Posidonia meadows are disappearing at an alarming rate. It is estimated that at least 34% of these underwater forests in the Mediterranean have already been lost, causing long-term damage not only to marine ecosystems but also to humans
Growing Threats:
Despite the critical role they play, Posidonia meadows are disappearing at an alarming rate. It is estimated that at least 34% of these underwater forests in the Mediterranean have already been lost, causing long-term damage not only to marine ecosystems but also to humans. Due to their extremely slow growth rate (just 6 cm/year), when a Posidonia meadow is destroyed, it may take over 100 years to regrow, if they ever recover with the challenges of climate change.
In Greek waters, the destruction is accelerating due to the lack of effective enforcement of the existing legislation. The biggest threat is uncontrolled and unregulated anchoring by over 35.000 recreational vessels that travel in coastal areas every summer. Frequently they anchor over the protected Posidonia meadows uprooting parts of the meadow. Other key threat factors include:
Replanting Hope: Innovation meets Restoration
In response to the threats facing these vanishing seagrass meadows, the Archipelagos Institute is taking proactive steps to reverse the damage.
Since 2018, the Institute has been developing and implementing innovative replanting techniques in collaboration with scientists from leading European universities. This approach involves replanting Posidonia fragments uprooted due to boat anchorage, which would otherwise be lost. Every few years in the rare event, when the seagrass meadows produce seeds, they are collected and grown into seedlings in the lab and are planted into the underwater gardens. Biodegradable materials are used to support the growth process. This task is a very challenging task as it requires regular care underwater by expert scientists-divers, year-round, for the first few years of their growth. These seagrass gardens are paving the way for similar efforts throughout the Mediterranean.
Protecting Seagrasses: A Shared Responsibility
The destruction of seagrass meadows is not just an environmental issue; it is a social and economic one too. Millions of people around the Mediterranean rely on healthy seas for their food, income, and way of life. We have the knowledge and tools to stop this destruction, but action is needed.
With the aim of restoring these vital ecosystems, the Archipelagos Institute has built key collaborations between scientists, authorities, and coastal communities, while working closely with fishers to record their invaluable local ecological knowledge. Their protection is a responsibility we all share. To learn more about and support the Archipelagos Institute’s conservation efforts, please visit our website: https://archipelago.gr
ROUTE BY SUPERFAST FERRIES. 2025
