Posidonia meadows are the “underwater forests” of the Mediterranean Sea. The Posidonia (Posidonia oceanica) is an endemic marine phanerogam from the Mediterranean that forms big meadows that can be distributed from the surface to more than 40 meters deep.
Despite being protected both nationally and internationally, Posidonia beds are suffering a critical regression. Boat anchoring is one of the main causes of this regression. To minimize this impact, the conservation actions that are carried out usually consist of creating mooring fields, where buoys are fixed to the seafloor normally using concrete blocks. Often, the installation of these mooring systems is not done properly, seriously affecting Posidonia and other seagrass meadows and causing even more impact than anchoring.
The aim of the project is to restore the Posidonia meadows present in the anchoring buoys fields of some important natural parks like Montgrí, Medes Islands, Baix Ter, and Cap de Creus.
This project has been carried out on behalf of the Infrastructure department of the Government of Catalonia.
The project has two phases:
First, a diagnosis is done in the anchoring fields in which the blocks of concrete affecting the Posidonia have been localized. These blocks are positioned through a GPS and a suitability assessment of their relocation or extraction is done in order to know how to act.
The second phase consists of the resettlement or extraction of the blocks in order to ensure the health of the Posidonia bed.
Throughout the year 2018, the diagnosis of 10 anchoring buoys fields – with a total area of 52 hectares- and 452 concrete blocks affecting the Posidonia have located.
The intervention has been made in the municipalities of Torroella de Montgrí (Montgrí Natural Park, the Medes Islands, and the Baix Ter), Roses and Cadaqués (Cap de Creus Natural Park).
In a first instance, 15 concrete blocks where relocated and a total of 139 where removed and transferred as waste into a controlled dump landfill. In addition to the concrete blocks, a total of 47 remains affecting the Posidonia where extracted.
Our team is currently planning a second phase for the extraction of the remaining of concrete blocks.
The Posidonia regression throughout all the Mediterranean is a concerning fact.
It is estimated that, in the last 50 years, the surface occupied by seagrasses such as the Posidonia, have reduced their presence by more than 30% in the Western Mediterranean.