Posidonia oceanica


Marine macrophytes are a very heterogeneous group of organisms, composed of macroalgae (eg Cystoseira sp. ) and marine phanerogams (eg P. oceanica ). Macrophyte species are considered essential in coastal ecosystems, as they play an essential ecological role, both for the large number of ecological functions they perform and for the services they provide to society with.


In addition to their high productivity and their role in the global carbon cycle and the fight against climate change, they are essentially involved in coastal hydrodynamics and sediment stabilisation, protect the coastline from erosion, improve water quality and provide shelter and food for a large number of species, creating breeding habitats and acting as a center of biodiversity. We are currently working with the following marine macrophytes:

Posidonia oceanica

Posidonia Oceanica is a marine plant that belongs to the seagrass family and, as such, is composed of roots, rhizome, leaves, fruit and flower. Furthermore, it is endemic to the Mediterranean Sea and is the oldest living colonial organism in the world, with an estimated age of 100,000 years.

Posidonia oceanica forms the foundations of the Mediterranean marine ecosystem and, as a primary producer, is a basic step in the trophic chain that provides food to countless marine organisms. In addition to being a source of food, many species rely on seagrass meadows for their survival as it provides the perfect setting for reproduction and refuge. We must also remember that it is not only animal species that depend on and benefit from sea grasslands. Rather, the benefits of a healthy seagrass meadow transcends the marine environment to the point of significantly influencing two of the most important industries on our islands; tourism and fishing.

There is no doubt that we are highly dependent on Posidonia Oceanica and that if it continues to suffer, the consequences will be devastating for our islands and the Mediterranean Sea.

460 Millions

square meters is the total area that Posidonia oceanica covers


species depend directly on the Posidonia oceanica meadows to survive

338 Trillion

kilograms of carbon are absorbed annually by Posidonia oceanica

+400 Millions

of euros is the socio-economic impact on the Balearic Islands

Our marine treasure

Posidonia oceanica is one of the most extensive and characteristic ecosystems of the Balearic Islands. With an area of ​​about 460.000.000 million square meters, this ancient plant forms grand meadows that dominate the Balearic seabed which gives it its characteristic, magical appearance.

Since its meadows are used as a place of reproduction, spawning or simply as a source of food, fish, epiphytes, mollusks, crustaceans and algae are many of the species that depend directly on Posidonia oceanica meadows.  Without them, the ecological balance of the Balearic Sea would disappear.

Posidonia oceanica is a plant and, as such, it photosynthesises; It uses energy from the sun to fix inorganic carbon (CO₂) and produce large amounts of oxygen. As a consequence of this process, Posidonia grasslands act as carbon reservoirs that store thousands of tons of CO₂ per year. This makes Posidonia oceanica an indispensable agent in the fight against global warming.

Apart from sequestering carbon and maintaining ecological balance, the benefits of Posidonia Oceanica go far beyond the realms of marine and environmental science. Sea grasslands are responsible for the crystal clear waters that our islands have become famous for and they support the marine diversity that attracts millions of people to the Balearics each year. For this reason, the mere presence of Posidonia Oceanica has an estimated value of around 400 million euros a year to the tourism and fishing industries alone.

C. Nodosa i Z. Noltii

Cymodocea nodosa and Zostera noltii are also plants belonging to marine phanerogams, which are distributed in the Mediterranean and in some parts of the Atlantic.

These species are less known, although they also form extensive grasslands in shallow water, creating habitat for many species, helping to purify water and capture carbon. These are very similar species to the naked eye, which can also be found forming mixed meadows of both plants.  

It should also be noted that, despite the large number of ecosystem services they provide,  C. nodosa and Z. noltii  do not enjoy the same protection as P. oceanica , and are, in many cases, highly threatened, to the point of being  Z. noltii  included in the National Catalog of Threatened Species of Spain.



A report by the International Union for the Conservation of Nature (IUCN) estimates that Posidonia oceanica meadows may be responsible for sequestering up to 40% of the carbon that is stored by coastal vegetation each year. In addition, one hectare of Posidonia Oceanica can produce more than three times as much oxygen as a hectare of tropical forest yet, regardless, it is estimated that the rate at which Posidonia oceanica is disappearing is up to eight times higher than the loss of these forests. There is no doubt that Posidonia Oceanica is a delicate organism and that if we do not work together to guarantee its future we may soon have lost not only the lungs of the Mediterranean but an indispensable agent in the fight against climate change.​ Thereby, we have adapted our scientific program, which includes studies of environmental impacts, proposals for new areas susceptible to a greater degree of protection and the restoration and regeneration of marine phanerogams.  

Marine regeneration is a community marine reforestation project in which innovative techniques are applied for the recovery of phanerogams in small areas. The scientific objectives of this project in particular are (1) to provide new tools for the restoration of marine habitats, (2) to regenerate areas degraded by anthropogenic activities, and (3) to regenerate blue carbon sinks. These stations will not only function as part of the regeneration program but also as a means to conduct educational programs, raise awareness and share scientific knowledge. Arrels Marines wants on one hand, to bring science closer to the population and, on the other hand, to bring the population closer to the sea. Therefore, the stations will be placed between 3 and 10 meters deep, making them accessible to everyone, whether snorkeling or scuba diving.  

Although Arrels Marines' priority is to consolidate an ambitious program, during the early stages of the project we prefer to go for a simple but effective growth formula with a clear structure.

How it works





First of all, a location that has been degraded or is suffering the direct effects of anthropogenic activity is chosen.

Next, we carry out an interpretive study of the area to determine the viability and, above all, the need to establish a station in this area.

Once the results are obtained, the study area is delimited to avoid anchoring and the regeneration phase begins by replanting marine phanerogams.

During the following weeks, a close follow-up is done to make sure the station is thriving and then we will move to the next area.



In Arrels Marines we are constantly working together with pedagogues and educators to create high-quality educational plans that can be presented to schools, institutes and universities. Our primary goal is to create attractive and didactic content that can be adapted to suit the needs of each group and, above all else, awakens the interest of students, allowing them to actively participate in workshops, excursions and even scuba courses.

We have no doubt that children are the future and it is therefore key to work alongside them, as we do. However, Arrels Marines doesn’t want to be limited to this. It is indispensable that we reach as many of the people who interact and have direct impacts on the environment as possible. Hence, we do not want to limit ourselves to educational centers; rather, we are working towards the creation of materials that can be used to raise awareness among adults as well.

Finally, from Arrels Marines, in our desire to bring the sea closer to the whole world, we work and adapt our programs to reach forgotten collectives such as the elderly, people with intellectual disabilities as well as hospitalised children and adults or those with reduced mobility.





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