Restoration of Posidonia oceanica Meadow Using Cuttings from an Area Impacted by Harbor Extension Project

In the Mediterranean Sea, restoration of marine habitats has mostly focused on the endemic seagrass Posidonia oceanica. Despite several transplanting experiments, large-scale projects are rare, and their success is poorly known. The present work describes a restoration project of a large, degraded area in northern Sardinia (Italy) using cuttings harvested from a donor meadow that was destined for destruction due to harbor expansion. The receiving site was selected through a multidisciplinary study including acoustic mapping, ROV surveys, sediment assessment, and analyses of satellite images across ten years to evaluate the site suitability. Plants were manually uprooted from the donor meadow and cuttings were selected and transplanted within 24 h by environmental engineering techniques. The cuttings were transplanted onto degradable mats of natural coconut nets coupled with a double-twist steel mesh and anchored to the bottom. Overall, 7000 patches, each containing 20 cuttings, were transplanted in three periods: June–July 2022, October–November 2022, and February–March 2023. One year after the restoration, all the patches were in situ, with an overall cutting survival of 59%. The results are comparable to those of previous small-scale projects using the same technique and also endorse its suitability for the restoration of large, degraded areas.