The Instituto de Ecología Litoral has sent the Calpe City Council the annual report on the state of the seagrass meadows on the beaches of Calpe and it is clear that the Arenal-Bol, Fossa and Cantal Roig beaches, from which samples have been taken and analysed, are in good condition.
The Posidonia oceanica meadow is distributed along the entire coastline of Calpe Bay; in the area between the port and Bol beach the Posidonia develops between 10 and 17 metres deep. Above is a meadow with a mixture of Cymodocea nodosa and Posidonia oceanica of lower density, locally called "vairassos".
In the western half of the bay, up to Cape Toix, the Posidonia meadow develops at a shallower depth of 4 metres to 20 metres. From Puerto Blanco to Morro de Toix there is, according to the report of the Instituto de Ecología Litoral, a continuous and very well preserved meadow.
To analyze the Posidonia meadows, density and coverage are used as parameters. Thus, the value of the sampling density on the beach of Arenal-Bol is 333'56 stalks/M², which is a normal average value within the depth range in which the meadow is located. The coverage on this beach was 72.79%, higher than in the previous year. The Fossa beach has a density of 453'61 stalks/m² and 68'15% coverage and the Cantal Roig beach has a density of 309'02 stalks/m² and a coverage of 80'53%.
The ecosystem of the Posidonia oceanica meadows is protected at European level by its great biodiversity and ecological value; at the same time, it is an ecosystem that is very sensitive to changes in water transparency, changes in salinity, mechanical erosion or lack of oxygen.