The role of seagrass meadows in the accumulation of microplastics: Insights from a South African estuary

Microplastics are widespread in marine ecosystems, where they threaten biota and human wellbeing. Seagrasses may act as natural filters of microplastics due to their particle trapping abilities, yet little is known about the extent of microplastics in the sediment of seagrass beds. The aim of this study was to compare microplastic accumulation in the sediments of Zostera capensis meadows with adjacent bare sediments at a small spatial scale (similar to 5 km) in the Knysna estuary in South Africa. No significant difference in total microplastic counts were found between seagrass and unvegetated sediments. However, fibre microplastic counts differed significantly between the two locations at which samples were collected. This may be due to pollution levels and proximity to larger human population densities. Importantly, our study reveals variability in microplastic abundance and type even at small spatial scales, an important consideration for the design of future studies aiming to monitor for microplastics.

Automated summary

This study aimed to compare microplastic accumulation in the sediments of Zostera capensis meadows with adjacent bare sediments in the Knysna estuary in South Africa. The results showed that there was no significant difference in total microplastic counts between seagrass and unvegetated sediments, but there was a significant difference in fibre microplastic counts between the two locations. This variability in microplastic abundance and type at small spatial scales is an important consideration for future microplastic monitoring studies.