Impact of the Costa Concordia shipwreck on a Posidonia oceanica meadow: a multi-scale assessment from a population to a landscape level

The Costa Concordia shipwreck permitted to assess how multiple disturbances affected marine biota at different spatial and temporal scales, evaluating the effects of mechanical and physical disturbances on Posidonia oceanica (L.) Delile, an endemic seagrass species of the Mediterranean Sea. To assess the impacts of the shipwreck and its salvaging from 2012 to 2017 at a population and a landscape level, a diversified approach was applied based on the application of a geographical information system coupled with seascape metrics and structural descriptors. Benthic habitat maps and seascape metrics highlighted cenotic transitions, as well as fragmentation and erosion phenomena, resulting in 9952 m2 of seagrass area impacted. Regression of the meadow was unveiled by both multivariate and interpolation analysis, revealing a clear spatio-temporal gradient of impacts based on distances from the wreck. Results highlighted the effectiveness of the descriptors involved that permitted to reveal temporal changes at both fine and large scales. •Concordia shipwreck affected P. oceanica at different spatial and temporal scale.•The studied meadow was subjected to mechanical and physical disturbances.•An impact gradient based on distances from the wreck was present.•Cenotic transitions, fragmentation, erosion and regression phenomena were reported.•Descriptors involved were effective in revealing fine and large-scale changes.