Seagrass restoration effectiveness remains uncertain probably due to the unique features of each species, the wide range of practices and methodologies used in transplanting actions, and suitability of reference sites.

This is a space-for-time substitution to evaluate the effectiveness of restoring the ecological complexity of Posidonia oceanica meadows, hypothesising that in successful operas the differences in structural epiphytic diversity between restored and local meadows will be reduced through time since transplanting. In summer 2025 seven Mediterranean sites, where restoration was conducted at different times using similar techniques, were investigated. In each site, the macro- and micro- epiphytic diversity of basal, intermediate, and terminal portion of transplanted P. oceanica leaves were compared to nearby meadows used as reference conditions. Overall, dissimilarity in leaf macroepiphyte community between restored and natural plants significantly decreased with restoration age, with an decrease in similarity from the basal to the apical portion of the leaf, while this pattern was not observed for the microepiphyte community.

Although results encourage the restoration effectiveness, they also highlight that the aim of restoring ecological complexity should be strongly time-dependent and that 8 years may still not be enough for the epiphytic community of P. oceanica meadows to be restored.