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Formentera Island


Conservation benefit: Seagrass protection

Community benefit: Mobile app that lets boats avoid anchoring on seagrass

Date Approved: 02.2020


This project protects seagrass, which traps more CO2 than any other marine ecosystem, slowing global warming.

If you’re a boat captain in the Mediterranean, you don’t want to drop anchor on sensitive seagrass beds, which are crucial for many ocean creatures. But you can’t always see the seagrass below your boat. How can you avoid damaging this critical ecosystem?

There’s an app for that.

The free app, which has been downloaded more than 4,000 times, lets boat crews know exactly where seagrass is. It relies on exquisitely accurate (within one meter) maps of the seagrass beds, made from data collected by lateral-scan sonar, drones, and divers. A Seacology grant is funding a nonprofit organization, the Vellmari Association, finish mapping the seagrass around Formentera Island, one of Spain’s Balearic Islands.

Recent studies suggest that in the western Mediterranean, seagrass (Posidonia oceanica) beds have declined by 34% over the last 50 years. Damage from anchors is a major cause. This project will help protect the largest and oldest Posidonia meadow in the Mediterranean, in the Natural Park of Ses Salines. In the summer, around 4,000 boats anchor there each day, destroying large areas of seagrass.

Seagrass is an unsung hero of biodiversity that creates huge, uniquely important ecosystems. Posidonia beds grow over centuries, forming beds several meters high and sinking deep roots. These meadows teem with fish, mollusks, starfishes, crustaceans, and plankton. The meadows protect the coast and beaches against erosion and keep the water clear.

Local people depend on them because they are crucial to fishing and tourism. In fact, all of us depend on seagrass, because seagrass ecosystems are the most efficient carbon sink of any ecosystem on the planet. They trap carbon and keep it out of the atmosphere for thousands of years.

The Vellmari Association hopes to keep gathering data. Eventually, it may map Posidonia meadows in other parts of Spain, France, Italy, and beyond.

Project Updates

June 2020

More mapping around Formentera Island is scheduled to start in June. Our project partners are in discussions with the environment minister of the Balearic Islands, hoping that the government will make the Posidonia MAPS app the official way for boats to avoid anchoring on seagrass beds.

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