The distribution and ecological effects of microplastics in an estuarine ecosystem. (1st November 2021)

• Record Type: Journal Article
• Authors: Hope, Julie A.; Coco, Giovanni; Ladewig, Samantha M.; Thrush, Simon F.
• Is Part Of: Environmental pollution. Volume 288(2021)
• Publication Date: 2021-11-01
• Subjects: Benthic ecology -- Ecosystem effects -- Ecosystem function -- Intertidal soft sediment -- Microphytobenthos -- Microplastics; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2021.117731
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Coastal sediments, where microplastics (MPs) accumulate, support benthic microalgae (BMA) that contribute to ecosystem functions such as primary production, nutrient recycling and sediment biostabilization. The potential interactions between MPs, BMA and associated properties and functions remain poorly understood. To examine these interactions, a survey of 22 intertidal sites was conducted. MP abundance, size and a suite of MP diversity indices (based on color and shape) were determined from surface sediments alongside biochemical and physical properties. MPs were detected at all sites and dominated by polypropylene (34%), polyester (18%) and polyethylene (11%). Fragment and fiber dominance (16–92% and 6–81% respectively) and color-shape category diversity varied significantly by site. Distance-based linear models demonstrated that estuary-wide, mean grain size and mud were the best predictors of MP abundance-diversity matrices, but variance explained was low (9%). Relationships were improved when the data was split into sandy and muddy habitats. In sandy habitats (<8% mud), physical properties of the bed (mean grain size, mud content and distance from the estuary mouth) were still selected as predictors of MP abundance-diversity (14% variance explained); but a number of bivariate relationships were detected with biochemical properties such as BMA associated pigments and organic matter. In muddy habitats (>8% mud), porewater ammonium was lower when fiber abundance and overall MP diversity were higher. The inclusion of porewater ammonium, organic matter content and pheophytins alongside physical properties explained a greater percentage of the variance in MP abundance-diversity for muddy habitats (21%). The results highlight the importance of examining plastic shapes and MP categories in addition to abundance and emphasize that functionally different habitats should be examined separately to increase our understanding of MP-biota-function relationships. Graphical abstract: Image 1 Highlights: Grain size was the main predictor for 'whole' estuary and sand habitats. Including NH4 + pools and organic matter (OM) improved predictions for muddy sites. No. fragments increased with mud (up to 8%); No. fibers increased with grain size. No. fragments higher in OM rich sites; fibers increased at low NH4 + sites. Interactions with sediment biochemical properties are an important consideration. Abstract : Biochemical properties of field sediments influence the abundance and diversity of microplastics across sedimentary ecosystems.