Seabed Status, Mapping and Assessing Posidonia oceanica in the Edough Mountains MPA, Annaba (Northeastern Algeria): A Baseline for Spatio-Temporal Monitoring

In the Mediterranean region, the number of Marine Protected Areas (MPAs) has been steadily increasing, though their distribution remains uneven between the northern and southern coastlines. Algeria has shown a growing commitment to protecting its coastal ecosystems. Despite Posidonia oceanica being the most significant and extensively studied seagrass species in the Mediterranean, efforts to compile and analyze comprehensive spatial data on its distribution across the basin are still limited. This study aimed to map the current distribution of P. oceanica meadows in the newly established MPA of the Edough Mountains in Annaba, located in northeastern Algeria. In 2023, the surface water quality in the area was found to be satisfactory, with an average temperature of 22°C, a pH of 8.09, salinity of 37, a dissolved oxygen concentration of 6.9 mg/l, and a total suspended solids concentration of 0.21 mg/l. The upper limits of P. oceanica meadows, along with surrounding soft and rocky habitats, were surveyed using GPS over a 37km stretch, from Cap de Garde to Roche Axine, covering half of the MPA. The survey, which included 278 stations, identified 97 seagrass beds in good conservation status, with minimal epiphyte presence, at depths ranging from -1.5 to -24 meters. These initial findings will serve as a reference for future spatio-temporal monitoring of the growth and health of these meadows.