Microplastic abundance and its relationship with sediment grain size in seagrass and bare flats of Panjang Island, Banten Bay, Indonesia

Microplastic accumulation in sediment is influenced by the grain size of sediment. Panjang Island, located in Banten Bay, has the potential to accumulate microplastics from bay-wide transport and local anthropogenic sources. This study assessed the relationship between sediment grain size and microplastics in seagrass and bare flat sediments. Sediment samples were collected from seagrass, seagrass edges, and non-seagrass areas at three stations (n = 9). Differences among sampling points were evaluated using Kruskal–Wallis, while relationship between microplastic and sediment grain size was assessed using Spearman’s coefficient and principal component analysis (PCA). Microplastic abundance ranged from 240 to 1.880 par kg-1 dw with no significant differences among sampling points (p > 0.05). Microplastics were dominated by fragments and fibers, with fine and medium sand being the dominant sediment grains. A positive correlation was observed between microplastic abundance and finer sediments (rs = 0,58), suggesting that microplastic increases with the proportion of fine sand. PCA results showed an association between microplastic abundance and sampling points located in seagrass beds, suggesting that seagrass may enhance microplastic accumulation in the sediments of Panjang Island.