Sail with awareness: Protect the posidonia of the Balearic Islands

by | 14 Mar, 2024 | Viajes | 1 comment

The world’s most valuable known emerald sold for 340 million dollars. It weighed over 340 kilos and even has a name. It is called Bahia.

Why am I telling you this? Because at the bottom of the Mediterranean Sea there is another hidden green gem of incalculable value. We are talking about the posidonia in the Balearic Islands, a living being declared Underwater Heritage of Humanity.

As you can imagine, any help for its conservation is welcome, and we sailors play a crucial role in it.

Keep reading because we tell you all about this natural treasure and how you can contribute to its conservation.

What is posidonia and why is it important in the Balearic ecosystem?

The Posidonia oceanica is a marine plant with flowers, fruits, and long, thin leaves, unique to the Mediterranean Sea.

It grows by forming large expanses in the shape of undulating meadows and is very slow-growing. Its existence is fundamental in the Mediterranean ecosystem, but why?

Let’s see.

Ecological importance

As we have already mentioned, posidonia is not an algae, but a marine plant. And its impact on the seabed goes far beyond being a simple Mediterranean inhabitant.

  • The posidonia contributes to the oxygenation of the water and fights climate change.
  • It protects biodiversity. It serves as a reserve for fish, mollusks, and crustaceans, as they are places for laying, shelter, and feeding.
  • It is the guardian of the beach. Due to its location near the coasts, the posidonia “absorbs” the wave action and causes the waves to break with less intensity on the beaches, preventing sand loss and protecting them from erosion.
  • This guardian helps the formation of sand since it is estimated that 75% of the beaches in the Balearic Islands are microscopic fragments of species linked in some way to posidonia.
  • It is a clear indicator of water quality, since it requires certain conditions to be able to develop.

Distribution of Mediterranean posidonia in the Balearic Islands

The meadows of posidonia are in alarming recession throughout the Mediterranean even though today it is a species protected by legislation. Yet, from time to time, vessels can be seen anchored on posidonia, and the damages have even been filmed, so there is much to do. The distribution of posidonia in the Balearics, island by island, is as follows:

Distribution of posidonia in Mallorca, Menorca, and in Ibiza and Formentera

Ubicaicón de la posidonia en Mallorca La posidonia en Menorca La posidonia en Ibiza-Formentera

*Images from

Six curious facts about posidonia

Here are some curious facts to help you get to know this peculiar inhabitant of the coasts of the Balearic Islands more deeply:

  • Between Ibiza and Formentera lies a Posidonia meadow 8 kilometers in diameter, considered the largest living being in the world.
  • It is the oldest species in the biosphere, with an age of 100,000 years.
  • Its stalks grow at an extremely slow pace, about one centimeter per year.
  • It is primarily responsible for the turquoise color of the waters of Ibiza and Formentera.
  • Its leaves can reach up to 1 meter in length.
  • The Balearic Islands have an extension of 55,795 hectares of posidonia meadow.
  • It is capable of capturing CO2 up to 20 times more than a terrestrial forest of the same size.
  • The Balearics contain the largest surface of posidonia in Spain, and its meadow represents 50% of the total in our country.
  • It is possible to sponsor a piece of the posidonia meadow from 1.00 €/m² and contribute to its conservation. You can do it here.

Threats and challenges

Now that we know many things about this amazing submarine plant, let’s detail the challenges that have put it in recession. The challenges threatening its existence are:

  • Maritime construction
  • Water pollution from spillages.
  • The progressive silting of coastal bottoms.
  • The artificial implantation of beaches.
  • Incorrect beach cleaning management.
  • The massive and uncontrolled anchoring of recreational boats.
  • Climate change, as if the water temperature exceeds 28 °C, the mortality of posidonia skyrockets.

Among all these problems, the anchoring of boats and water pollution stand out above the rest. Keep reading to discover how it affects them!

  • Massive anchoring. The anchors and chains from recreational boats that fall on the meadows seriously damage them, so one should always anchor in allowed places or using the buoys provided for this purpose.
  • Discharges into the sea. Both from boats and from wastewater treatment plants or industries, pollutants affect the growth of the posidonia meadow.

Conservation efforts for oceanic posidonia in the Balearics

There is legal protection (both national and European) of posidonia as a wild species. The aim is to ensure its state of conservation and that its natural distribution area is not reduced.

However, regulation adapted to the reality of the Balearic Islands is necessary, making the existence of human activities compatible with the protection and conservation of the species and habitat.

Regarding the regulation of boat anchoring, in general, anchoring over oceanic posidonia is prohibited. And it can only be done using low-impact systems (individual buoys or buoy fields) authorized according to the regulations on coasts.

Under no circumstances should we anchor directly over the posidonia meadow. Furthermore, the pumping out of bilges or dumping of waste within a buoy field is considered an aggravating circumstance.

What can you do to contribute to its conservation?

As sailors and lovers of the Balearic Islands, we have the responsibility to collaborate in improving the future prospects of this green gem.

Part of the charm of the Balearics is its turquoise waters, and now that you know who is responsible for them, you should take care of it. From Nautic Adventure, we ask you to pay special attention to the prohibited anchoring areas.

Here are some recommendations that you can follow:

  • Check the seabed with the depth sounder or the instruments you have available.
  • Use the GOIB Viewer to find the most optimal anchoring.
  • Use low-impact anchoring systems.
  • Take into account the dimensions of your boat and the wind: The larger the length and wind, the more chain and further from the meadow you should anchor to avoid damaging it.
  • Do not pour bilge water at the anchoring point. Do it in places enabled for this purpose or at least, more than 12 miles from the coast.
  • Engage the engine forward when lifting the anchor so that it rises vertically and there is less risk of erosion.
  • You can download these two apps to consult them in case of doubt:
    Donia for Android
    Donia for iOS
    PosidoniaMaps for Android
    PosidoniaMaps for iOS

As we have seen, the Mediterranean ecosystem cannot be sustained without the meadows of oceanic posidonia. We hope to have raised your awareness and that you collaborate in the conservation of posidonia in the Balearic Islands.

Take care of it when you rent a boat in the Balearic Islands with us!

Source:, Balearic Sea Report, Sergio Arribas