Protecting Posidonia to Preserve Ibiza and Formentera’s Land and Sea

21 March, 2019

Ibiza and Formentera’s crystal-clear waters and sandy beaches are famous around the world and enjoyed by locals and millions of visitors every year. What makes our waters so clear and beaches so beautiful lives and breathes at the bottom of the sea. Posidonia oceanica, a seagrass endemic to the Mediterranean, forms vast underwater meadows that are critical to our ecosystem.


Over the past ten years, the Ibiza Preservation Foundation (IPF) has supported numerous local environmental projects that have played a crucial role in promoting the health and prosperity of Ibiza and Formentera. It’s no surprise then that protecting Posidonia is now one of the IPF’s key projects to preserve our land and sea.



Posidonia is one of the world’s oldest living organisms, and meadows in Ibiza and Formentera are recognised by UNESCO as World Heritage. Over thousands of years, it grows and creates reefs up to four meters high that protect the coastline and beaches from erosion. The meadows provide an important breeding ground and home for hundreds of fish species, while the skeletons of organisms that once lived in the meadows erode over time to form sand. Posidonia also purifies the water, provides an important carbon sink for the Mediterranean and releases oxygen. It’s estimated the meadows in Ses Salines Natural Park alone produce enough oxygen for the entire population of Ibiza.


But Posidonia has become seriously threatened. Coastal construction, untreated wastewater discharges, climate change and boat anchoring have destroyed thousands of square metres of meadows. It’s estimated 34% of the Posidonia meadows in the Western Mediterranean have been lost in the past 50 years. And with one square metre taking 100 years to generate, this loss could have a serious impact on our environment.


To provide a clear picture of the current size and state of meadows around Ibiza and Formentera, the IPF is helping to fund work to map Posidonia. Initiated in Formentera by Vellmarí, this mapping work is being led by marine biologist and National Geographic underwater image director Manu San Félix. Now, over 80% of the meadows around Formentera have been mapped. These maps will provide a tool to monitor the impact of pollution, climate change and boats’ anchors over time.



A practical application of this work is the development of a mobile app. Designed for sailors; the free Posidonia MAPS app provides access to these underwater maps to help guide boats in real-time, especially in conditions with low visibility, to prevent anchoring on Posidonia.


As well as educating the boating community on the importance of Posidonia, a children’s education programme is being rolled out at schools in Formentera. Posidonia storybooks, snorkelling expeditions and workshops will teach children about the value of the meadows and the need to preserve them. And ‘Posi’ ambassadors will carry this message out into the local community.


The IPF is also calling for the improved treatment of wastewater discharged to sea to protect Posidonia. This work is being carried out by the Water Alliance, which the IPF established to address the islands’ water shortage, treatment and management issues.


To support this important project to protect Posidonia meadows, you can download the Posidonia MAPS app, buy the children’s ‘Posi’ storybooks and make a donation to the IPF.




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