Connectivity-based approach to guide conservation and restoration of seagrass Posidonia oceanica in the NW Mediterranean

Marine population connectivity involves organism movement and interactions in oceanic and coastal settings. It is essential for biodiversity by aiding genetic diversity, species distribution, and recovery from disturbances. It guides resource management strategies like fisheries and conservation planning, ensuring marine ecosystem sustainability. Seagrass meadows play a pivotal role within coastal ecosystems, contributing to essential ecological, physical, and economic functions. Despite the presence of protective policies, a continuous decline of seagrass meadows has been observed in recent years due to the impact of human activities and climate change. In the Balearic Islands of the Mediterranean Sea, these pressures are further intensified by tourism, underlining the pressing requirement to prioritize areas for protection and restoration while considering the connectivity between habitat patches. In this study, the dispersal of Posidonia oceanica, the most widespread seagrass species in the Mediterranean Sea, from semi-enclosed bays and nearshore locations within the Balearic Islands archipelago, is investigated using a high-resolution hydrodynamic model and an individual-based model. The simulations were subjected to analysis through a graph-theoretic approach, revealing significant variations in dispersal probabilities across different years. Notably, Alcudia Bay emerged as a prominent sink, while critical links were identified between Menorca and Mallorca, as well as between Mallorca and Ibiza. This study underscores the value of dispersal modelling and network analysis in conservation planning for foundational species, particularly within a regional, integrated framework of conservation management.