A georeferenced dataset of Posidonia oceanica deposits and banquettes for mapping and coastal management along Mediterranean seashores

Posidonia oceanica (L.) Delile is a keystone seagrass species endemic to the Mediterranean Sea, forming extensive meadows that provide essential ecological services. A key but often overlooked component of its life cycle is the accumulation of deposits along the shorelines, sometimes forming permanent terrace-like structures called banquettes. Despite their numerous ecological functions, banquettes are often subject to unsustainable management practices (i.e. removal and landfilling) due to conflicts with tourism and lack of regulatory framework, leading to environmental degradation and ecosystem service loss. This study provides the first Mediterranean-scale investigation of P. oceanica deposits and banquettes through Geographic Information System (GIS)-based mapping of beaching sites. The approach integrates spatial information on banquettes—collected from peer-reviewed literature—with additional geospatial layers (e.g., seagrass meadow distribution, beach use, and protected areas), generating a comprehensive map that summarizes the current distribution of beaching sites. Our findings demonstrate the effectiveness of GIS and remote sensing tools for dynamic, large-scale monitoring of Posidonia deposits, including banquettes, and related anthropogenic pressures, thereby improving scientific understanding of the complex beaching process. The resulting georeferenced dataset of P. oceanica beaching sites along the Mediterranean coast represents a significant step forward in supporting decision-making and promoting sustainable coastal management. Nevertheless, the need for harmonized monitoring protocols, transnational cooperation, and further integration of remote sensing data clearly emerges from this work.