Comparison of macroplastics dynamic across a tidal-dominated coastal habitat seascape including seagrasses, salt marshes, rocky bottoms and soft sediments

Coastal environments are usually composed by heterogeneous coastal-seascape, which can modify macroplastics accumulation dynamic. We evaluated seasonally the litter trapped on tidal-dominated habitats including two seagrass species, salt marsh, sandy beach, bare sediment and rocky bottom. Vegetated habitats showed the highest plastic accumulation in autumn-winter seasons, especially in medium-lower tidal-elevation zones. Sea-grasses accumulated most of the degraded macroplastics, whereas averaged smaller sizes of litter were found in the salt marsh. The trapping ability of macrophytes was related to aboveground-biomass properties (i.e., height, width or flexibility) rather than shoot-density. Sandy beaches exhibited the highest plastics accumulation matching with the touristic-peak in the area, whereas rocky bottom was an important sink for macroplastics. This study provides authorities with comprehensible information to address the marine plastic litter problem taking into account the habitat-connectivity, the litter trap-ability of macrophytes and the tidal-elevation influence in order to improve future actions to deal with plastic pollution.

Automated summary

Coastal environments play a role in the accumulation of macroplastics, with seagrasses and salt marshes being the main accumulation areas, sandy beaches being the main accumulation area for marine plastic litter, and rocky bottoms acting as important sinks for macroplastics.