Large-Scale Re-Implantation Efforts for Posidonia oceanica Restoration in the Ligurian Sea: Progress and Challenges

Abstract

The Ligurian Sea (NW Mediterranean) has been a focal point for numerous interventions aimed at restoring Posidonia oceanica meadows. The success of pioneer restoration actions in France during the 1970s stimulated similar initiatives across the Mediterranean Sea. Early attempts in the Ligurian Sea were implemented in 1993 and 1996 on limited seabed areas (i.e., tens of square meters) at the two coastal sites of Sori and Rapallo (Liguria, NW Italy). No further initiatives have been reported for the Ligurian Sea until 2022. In that year, a large-scale restoration project, which uses biodegradable mats coupled with metal mesh, began in Liguria. Different levels of anthropogenic pressure and wave exposure characterize the three investigated locations: (1) Portofino, on the eastern Liguria and on the border with the Portofino Marine Protected Area; (2) Bergeggi in the central Liguria and within the Isola di Bergeggi Marine Protected Area; and (3) Sanremo in the western Liguria, without any formal protection. Despite recent setbacks caused by severe storms in late 2023, which particularly damaged the Portofino site, ongoing monitoring revealed promising survival rates. Most notably, the site in Bergeggi displayed a 90% survival rate in September 2023. Although challenges to restore P. oceanica beds persist, such as mitigating damages caused by unpredictable events, this extensive re-implantation initiative offers the opportunity to evaluate the effectiveness of new basin-scale restoration strategies. This approach marks an important step in the conservation of Posidonia oceanica habitat.