Testing a nature-based solution for transplanting the seagrass Posidonia oceanica

Mediterranean seagrass meadows formed by Posidonia oceanica underpin coastal ecosystem functioning but are rapidly declining under cumulative anthropogenic pressures. In the Adriatic Sea, where meadows are sparse and fragmented, effective restoration strategies are urgently needed to enhance resilience without further degrading donor habitats. We developed and tested a non-invasive transplantation method based exclusively on organic and natural materials, and on the recovery of naturally uprooted P. oceanica bundles. The approach was implemented in the Tremiti Islands Marine Protected Area (Italy, Adriatic Sea) using shoots displaced by human activities and natural processes during summer 2022 and thus avoiding extraction from wild meadows. Transplants were monitored over 3 yr to assess persistence, density, and cover. Natural P. oceanica meadows in the study area were investigated to compare patterns observed in transplanted meadow areas. Persistence and consolidation of transplanted shoots showed 86% of initial shoot density and 74% of seagrass cover retained after 3 yr. Density proved to be the most reliable metric for monitoring, while cover offered a rapid seasonal assessment at the end of the vegetative period. The method may be applied to any other P. oceanica meadows, as well as to other seagrass species under similar conditions. This study represents the first transplantation of P. oceanica in the western Adriatic Sea. The method used avoids the extraction of cuttings from healthy donor meadows and the use of artificial inorganic materials, representing a nature-based solution. When combined with measures aiming to reduce ongoing mechanical stress, such an approach may contribute to the conservation and recovery of seagrass meadows.