Posidonia Spheroids Intercepting Plastic Litter: Implications for Beach Clean-Ups

This study represents the first assessment of plastic waste within Posidonia spheroids on four sandy, Mediterranean beaches, each characterized by varying levels of anthropogenic influence. Fifty-five (68.7%) spheroids, out of eighty examined, included plastic litter. A total of 202 plastic items were isolated. Plastic abundance was 2.5 items/spheroid corresponding to 132 items per kilogram. The length of plastic items ranged from 0.1 to 50 mm. Fibers, tangled fibers and fragments were the most common shapes. The spheroids exhibited a substantial capacity for trapping plastic waste, with notable differences among the beaches. Our results underscore the significance of implementing a beach clean-up plan aimed at removing all spheroids to prevent them from disintegrating and releasing trapped plastic waste into the environment. Manual removal is recommended to safeguard the beaches, and this process should target all spheroids, regardless of their size. This study provides valuable insights that can inform marine litter monitoring programs, contribute to the development of tailored management measures, and support the implementation of specific action plans to mitigate Mediterranean microplastic pollution.