The Institute of Coastal Ecology has sent Calpe Town Council its annual report on the state of the Posidonia oceanica meadows along the Calpe coastline, which shows that the meadows studied at the sampling stations corresponding to the Arenal-Bol, La Fossa, Cantal Roig and Cala Racó beaches are in good condition.
The study is part of the POSIMED programme, which aims to determine the state of conservation of the Posidonia oceanica meadows in the province of Alicante and to promote, through knowledge and participation, the need to preserve these habitats among the population.
The Posidonia oceanica meadow is distributed throughout the coastline of Calpe Bay, in the area between the port and Bol Beach, where it grows at a depth of between 10 and 17 metres. Beyond its upper limit, there is a mixed meadow of Cymodocea nodosa and Posidonia oceanica, with a lower density, which is locally known as ‘vairassos’.
In the western half of the cove, up to Cabo de Toix, it grows from a shallower depth (4 m) and extends to 17-20 m. From Puerto Blanco to Morro de Toix there is a continuous and very well-preserved meadow. In the deepest part of this sector, some degradation has been detected due to erosion caused by illegal trawling. Finally, in the area north of Peñón de Ifach, the Posidonia meadows are well developed to depths of over 20 metres.
Density and coverage are used as parameters to analyse Posidonia meadows. The average density value of Posidonia oceanica during 2025 was 531.94 bundles/m², lower than in 2024 (593.06 bundles/m²) and 2023 (625 bundles/m²), although this difference can be considered normal and is caused by the natural variability of the species and the randomness of the sampling. The coverage of Posidonia oceanica was 60.49%, in line with the data for 2024 (55.64%) and 2023 (73.25%).
These variations can be explained by the sampling methodology. Based on the data, the Posidonia oceanica meadow can are in a favourable state of conservation.
Furthermore, based on the information on density, coverage and overall density index obtained over the last 23 years, the meadows at the Calpe station are in good environmental condition, with density showing a positive trend and coverage remaining stable. What is more, around Arenal Bol beach, meadow coverage is increasing.
The ecosystem formed by Posidonia oceanica meadows is protected at European level due to the great diversity of species it harbours and its ecological value. At the same time, it is an ecosystem that is very sensitive to changes in water transparency, salinity, mechanical erosion and anoxia.
The study by the Institute of Coastal Ecology, funded by the Provincial Council, is part of the POSIMED programme for monitoring Posidonia oceanica meadows, the only one in Spain that has been carried out continuously for the last 25 years.