Long-term response of Posidonia oceanica meadow restoration at the population and plant level: implications for management decisions

Abstract

In recent years, numerous efforts to transplant Posidonia oceanica have been carried out in the Mediterranean Basin for experimental and large-scale restoration purposes. However, data on the long-term outcomes of these initiatives remain scarce. This study aims to address this gap by investigating the long-term response of transplanted P. oceanica at both the population and plant level in comparison to adjacent natural meadows. We report on two large-scale transplantation sites in Italy: Santa Marinella in the Central Tyrrhenian Sea and Ischia Porto in the Southern Tyrrhenian Sea, assessing their progress 14 and 10 years after transplantation, respectively. Descriptors of the meadows and of individual plants were investigated through field and laboratory activities. Sampling was conducted in both transplanted and adjacent control areas within the natural P. oceanica meadow. After about a decade, shoot density in the transplanted areas equaled that of the natural ones. Nevertheless, phenological and lepidochronological descriptors in the transplanted areas still did not match those of the natural meadows. Our work provides crucial information into the restoration process of P. oceanica, with implications for managing this habitat in line with recent EU marine legislation.