Monitoring the Posidonia seagrass

The project

Posidonia is a seagrass whose meadows cover 633 km² of coastal sea beds in the Balearic Islands (Álvarez et al., 2015). Because of how widespread and hardy they are, these meadows are the fundamental element that conditions the Balearic Islands coastline, the stability of both the coast and its beaches, the water transparency and its biodiversity. However, there is a lack of information on the real status of the viability of these meadows.

There is a successful precedent of citizen collaboration, the Posidonia Monitoring Network, which the Fisheries and Marine Environment Administration had for 12 years (1999-2011) and which was an extraordinary instrument for monitoring the meadows.

This monitoring network ended up having 36 stations spread across the four main islands (18 in Mallorca, 14 in Menorca, two in Ibiza and two in Formentera), where annual monitoring recorded both density and coverage, the presence of invasive algae, and the density of indicator species such as those that produce mother-of-pearl and sea urchins.

The objective is to rebuild this network, in an attempt to recover the same stations that were in place in 2012, or to set up new stations close to those that had existed in the past. Recovering the network involves not just locating or replacing the material installed in the sea (sampling panels, spikes, markers, etc.), but also rebuilding relationships of trust and joint responsibility between the public administration and volunteers.

The aim of the project is for the monitoring of Posidonia seagrass meadows in the Balearic Islands to provide high-quality information from data on the entire Balearic marine territory, which may also help to improve the management of and planning for this habitat and anthropic activities carried out in the same area.