Microplastics in mangrove and beach sediments on southeast Florida barrier islands

Coastal estuaries and beach systems are at high risk for microplastic pollution. The distribution, abundance, and hazards microplastics present in these coastal environments is not fully understood but are widely recognized as needed to support efforts aiming to protect and enhance these valuable systems. This project aimed to quantify the abundance and variation of microplastics in estuarine mangrove and open coast beach sediments on Southeast Florida barrier islands. Barrier islands serve as a buffer between Florida’s wetland environments, reefs, and other marine habitats and may serve as a conduit or temporary sink for microplastics entering the ocean. There have been no extensive studies or monitoring efforts evaluating microplastics in Southeast Florida barrier islands sediments, nor comparing geomorphic properties of an area on microplastic accumulation. Study sites included back barrier estuarine mangroves and open coast beaches at three regionally similar but geomorphically distinct study sites throughout Palm Beach County, Florida. The sites were sampled seasonally in 2022 (i.e., summer and winter) to quantify the spatiotemporal distribution of microplastics. Microplastic abundance, color, shape, and size was documented. Sediment samples were analyzed for moment method statistics (i.e., mean, standard deviation/sorting) at quarter and half-phi intervals above 63 μm. This novel study quantified spatiotemporal variability of the microplastic pollution conditions in Southeast Florida barrier islands mangrove and beach sediments, where previously no data existed. This research is important for coastal managers to gain a better understanding of current microplastic pollution conditions and the factors influencing them to inform best management and conservation practices.