Microplastics interact with benthic biostabilization processes

Abstract Marine microplastics (MPs) accumulate in sediments but impacts on ecosystem functions are poorly understood. MPs interactions with stabilizing benthic flora/fauna or biostabilization processes, have not been fully investigated, yet this is critical for unraveling MPs effects on ecosystem-scale processes and functions. This is also vital for understanding feedback processes that may moderate the stock and flow of MPs as they are transported through estuaries. The relationships between sedimentary MPs, biota, environmental properties and sediment stability from field sediments, were examined using variance partitioning (VP) and correlation analyses. VP was used to identify common and unique contributions of different groups of variables (environmental, fauna and microplastic variables) to sediment stability. The influence of microplastic presence (fragment/fiber abundances and microplastic diversity) on sediment stability (defined using erosion thresholds and erosion rates) was demonstrated. Furthermore, MPs appeared to mediate the biostabilizing effects of environmental properties (including microorganisms) and fauna. Environmental properties and sediment stability could also explain the variation in MPs across sites suggesting biostabilizing properties may mediate the abundance, type and diversity of MPs that accumulate in the bed. The potential for MPs to influence biota and biostabilization processes and mediate microplastic resuspension dynamics within estuaries is discussed.