Cala Blanca : A second dive into our Spanish pilot site

Last July, the ARTEMIS team led by project partner OBSAM returned to the Spanish pilot site of Menorca, this time focusing on a second work field that complements our ongoing efforts in Cala Blanca pilot site (Read the previous activity in Cala Blanca site here). 

While the site has already offered us a wealth of insights into the state of Posidonia oceanica meadows, this summer fieldwork centered on two main strands:

Fish census : ARTEMIS researchers carried out systematic counts of fish populations across the meadow, an essential step to estimate the biodiversity levels associated with the habitat. Healthy Posidonia meadows provide refuge and nursery grounds for numerous species, and understanding the fish community structure is key to tracking ecosystem resilience. ‘We work in two zones, the impacted area and the non-impacted area, in both, the fish indicator of fish census was low, and the individuals observed were predominantly small-sized.’ noted Eva Marsinyach, one of the researchers that carried this activity from OBSAM. 
Additionally it has been noted that the area is open to fishing, and previous studies report similar patterns. In short, Menorca’s underwater seascapes are well preserved but comparatively poor in ichthyofaunal abundance.

ARTEMIS pilot site activities July 2025

Desalination plant outfall monitoring : In parallel with ARTEMIS’ seagrass assessments, partners conducted sampling near a local desalination plant. These measurements are designed to explore potential brine-related impacts on Posidonia oceanica meadows. In the case of Cala Blanca, Menorca, the main seawater desalination plant serving the area is located in Ciutadella and was built to supply potable water to local residents and the growing tourist population. Recent projects aim to minimize waste and improve water management, but the high salinity and occasional chemical additives in outfall can threaten marine habitats if not properly managed. Given the Mediterranean’s increasing reliance on desalination for freshwater supply, this line of inquiry is especially relevant for ensuring that water security solutions do not come at the expense of marine ecosystems.

• Endofauna (infauna) analysis: With support from Dr. Raül Triay, marine ecologist, our team processed the animals living in the seabed sediment (infauna) from both the impacted and the non-impacted zones. The activity involved collecting three small sediment cores (samples) per zone and was followed by an identification of the species and quantification of individuals present.

ARTEMIS Endofauna Lab analysis

In the non-impacted meadow, most of the sediment-dwelling animals were detritivores, they feed on decomposing Posidonia leaves and tiny organic fragments that settle on the seabed. ‘That’s what we expect in well-conserved Posidonia meadows, where there’s a steady trickle of plant debris.’ said Marsinyach.

In the impacted meadow, the community was more evenly mixed: alongside detritivores our team found many deposit feeders (which ingest and process sediment), suspension/filter feeders (which strain particles from the water), and carnivores/omnivores. This points to lower or less stable detrital inputs under impact, so strict detritivores become less dominant and other feeding groups take a larger share.

ARTEMIS | Project Partner OBSAM – Eva Marsinyach

“The Mediterranean’s Posidonia oceanica meadows are not only biodiversity hotspots but also powerful carbon sinks and coastal protectors. – the ARTEMIS team from the Observatori Socioambiental de Menorca (IME – OBSAM) explains – By combining biodiversity surveys with targeted

assessments of anthropogenic pressures, ARTEMIS is generating actionable knowledge for policymakers and coastal managers. The insights gained from this second site sampling will strengthen our ability to recommend practical solutions that safeguard these meadows.” highlighted (Eva Marsinyach, researcher of the ARTEMIS Team in IME-OBSAM)