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Posidonia - The Amazon forest of the Mediterranean Sea
© A.Rosenfeld

In spite of how it looks, Posidonia oceanica is not an algae – it is a plant with long, ribbon-like leaves flourishing in the oceans. Its history begins 70 to 100 million years ago, when flowering land plants colonized the ocean floor. Thus a remarkable marine ecosystem was born. It offered unparalleled services for the whole of our planet and it still continues to do so now, in the modern age. Posidonia meadows have overcome all climatological extremes since dinosaurs’ times. But now their future is at stake.

Posidonia oceanica is a species of seagrass endemic to the Mediterranean Sea. Forming underwater meadows, it creates essential living habitats for thousands of marine species. Many fish species depend on these habitats for their regular living and feeding grounds. For others, the meadows are vital reproductive areas, offering shelters to spawn and nurseries for the juveniles. 

However, providing biodiversity refuge is but one of the ecosystem services of Posidonia meadows. The other services, like carbon sequestration and coastal protection against erosion, are of no less importance. Economically speaking, the monetary value per hectare of Posidonia meadows exceeds by far that of coral reefs and the Amazon rainforest.

Posidonia habitats are fundamental to Mediterranean biodiversity, offering breeding ground and refuge to more than 400 plant and 1,000 animal species.

© Istock/WWF Mediterranean
An invaluable treasure at threat

The Mediterranean region has over 2 million ha of Posidonia oceanica meadows distributed along its coastlines.

But over the last 50 years, we have lost an estimated 34% of Posidonia meadows. The cause of this loss is mainly anthropogenic and consists of pressures such as anchoring, pollution, and climate change. 

When seagrass ecosystems are degraded or destroyed, their carbon sink capacity is adversely affected or totally lost, and the otherwise stored carbon is released, resulting in increased emissions of CO2. It’s plain to see that the loss of Posidonia is disastrous for Mediterranean life and its biodiversity, and it irreversibly contributes to climate change.



Preserving Posidonia oceanica is the key solution to tackle climate change and biodiversity loss in the Mediterranean.

WW has launched one of the largest regional initiatives to preserve Posidonia oceanica across the Mediterranean. By 2027 we aim to protect over 7.5% of the remaining Posidonia meadows in our sea.

By engaging with local communities and institutions, national and regional policymakers, scientists and financial bodies we aim to pilot solutions that will reduce the multiple threats to Posidonia - from anchoring to illegal fishing and pollution - and frame the adoption of science-based policies and area-based measures such as no-anchoring zones for the protection of these habitats serving as nurseries for fish and many other marine species.

At the same time we aim to create new financial systems to secure the income and livelihood of local communities while reducing their dependence on activities that may harm Posidonia meadows. 

WWF advocates for measures that will protect Posidonia from multiple threats, including boat anchoring, illegal fishing and coastal pollution.

© Anna Barbanti/WWF Mediterranean