© José Escaño Mooring scar posidonia

The Challenge

Algae and seagrass communities are essential for the well-being of coastal communities, offering clear waters full of life, essential for sustainable tourism.

They are also key habitats to replenish fisheries, acting as carbon sinks and as a protective barrier against the effects of climate change such as coastal erosion caused by storms.

Unfortunately, they are at serious risk of degradation caused by human activity.


Many seagrass and seaweed species are what we call habitat-forming species; i.e. those that create a habitat, providing resources which were previously limited or non-existent, such as food or shelter.

In addition to creating this habitat that can be used for many other species, many also provide essential services to coastal communities like maintaining attractive landscapes for touristic activities, replenishing fish stocks or protecting the coast against the increasing erosion caused by climate change.

The loss of marine plants due to human activities is one of the most urgent problems in nature conservation worldwide:

  • Of the approximately 177,000 km2 of seagrass that exist throughout the world, it is estimated that between 7 and 19% of its current surface (about 33,000 km2) has been lost; that is the equivalent of the area of more than 4 million football fields. Only in the Mediterranean, it is estimated that 446 km2 (more than 62 thousand football fields) have been lost.
  • Many seaweed forests of the genus Cystoseira have severely declined in recent decades. There are 47 species of Cystoseira in the world, and the Mediterranean host 32 of them, almost 50% of which are endemic (they only exist here). In the Balearic Islands there is still a great diversity of these species, which have already disappeared from many coastal areas of the Mediterranean basin. Unlike other seaweed species, Cystoseira reproduce only locally, and cannot colonize distant areas on their own. Therefore, to recover these forests in the areas where they have disappeared, it is necessary to carry out reforestation actions.

Furthermore, the species that thrive in shallow water areas are the most affected because they are in a borderline environment, exposed to impacts of both land and marine origin. This situation is especially serious in the Mediterranean; despite being one of the seas that harbours the highest biodiversity in the world, it is also one of the most threatened by human activities. This is mainly due to the fact that there is little exchange of water with the ocean (it is a semi-closed sea), its coasts are highly inhabited and there is a huge maritime traffic.