The role of plants in the face of marine litter invasion: A case study in an Italian protected area

Highlights: • Artificial polymer materials were the dominant waste type. • Increase of litter after bathing season at sites not cleaned regularly. • A spatial scale of 16 m² is efficient in detecting variability of litter. • Dense vegetation traps litter and limits its transport. • Plants are a relevant component to be considered in the analysis of litter. Marine litter accumulates in coastal dunes and causes severe damages to these fragile ecosystems. This study analyzed the composition, cover and distribution of marine litter and its relation to vegetation cover in a Mediterranean dune system, located in a protected area facing the Ligurian Sea (Northern Italy). We sampled twenty-two permanent multiscale plots in spring and autumn. Litter was detected in all plots and artificial polymer materials were the dominant type (85%). Litter categories increased from spring to autumn mainly due to seaside tourism. The largest spatial scale (16 m²) explained the variability in waste composition better than the smaller ones (4 m², 1 m²). Finally, the vegetation cover correlated inversely with the turnover of litter categories, suggesting that plants may act as a barrier to litter transport by trapping it, and that they play a role in the spatio-temporal dynamics of coastal litter.