Are the tidal flooded forests sinks for litter in the Amazonian estuary?

Comparison of macroplastics dynamic across a tidal-dominated coastal habitat seascape including seagrasses, salt marshes, rocky bottoms and soft sediments

Coastal environments are usually composed by heterogeneous coastal-seascape, which can modify macroplastics accumulation dynamic. We evaluated seasonally the litter trapped on tidal-dominated habitats including two seagrass species, salt marsh, sandy beach, bare sediment and rocky bottom. Vegetated habitats showed the highest plastic accumulation in autumn-winter seasons, especially in medium-lower tidal-elevation zones. Seagrasses accumulated most of the degraded macroplastics, whereas averaged smaller sizes of litter were found in the salt marsh. The trapping ability of macrophytes was related to aboveground-biomass properties (i.e., height, width or flexibility) rather than shoot-density. Sandy beaches exhibited the highest plastics accumulation matching with the touristic-peak in the area, whereas rocky bottom was an important sink for macroplastics. This study provides authorities with comprehensible information to address the marine plastic litter problem taking into account the habitat-connectivity, the litter trap-ability of macrophytes and the tidal-elevation influence in order to improve future actions to deal with plastic pollution.

First record of plastic ingestion by a freshwater stingray

The abundance and dispersion of plastic particles in aquatic ecosystems has become pervasive resulting in the incorporation of these materials into food webs. Here we describe the first record of plastic ingestion by the freshwater white-blotched river stingray Potamotrygon leopoldi (Potamotrygonidae), an endemic and threatened species in the Xingu River, Amazon basin. Potamotrygonidae stingrays inhabit exclusively Neotropical rivers, occupying rocky substrate habitats and feeding mainly on benthic macroinvertebrates. The gastrointestinal tract of 24 stingrays were analyzed, 16 (66.6 %) of which contained plastic particles. In total, 81 plastic particles were recorded and consisted of microplastics (< 5 mm, n = 57) and mesoplastics (5-25 mm, n = 24). The plastic particles found were classified into fibers (64.2 %, n = 52) and fragments (35.8 %, n = 29). The predominant color was blue (33.3 %, n = 27), followed by yellow (18.5 %, n = 15), white (14.8 %, n = 12), black (13.6 %, n = 11), green (6.2 %, n = 5), transparent (4.9 %, n = 4), pink, grey and brown (2.5 %, n = 2, each) and orange (1.2 %, n = 1). No significant correlation was observed between the number of plastic particles and the body size. Eight types of polymers were identified in the plastic particles analyzed using 2D FTIR Imaging. The most frequent polymer was artificial cellulose fiber. This is the first report of plastic ingestion by freshwater elasmobranchs in the world. Plastic waste has become an emerging problem in aquatic ecosystems globally and our results provide an important datapoint for freshwater stingrays in the Neotropics.

Measuring riverine macroplastic: Methods, harmonisation, and quality control

River systems are a key environmental recipient of macroplastic pollution. Understanding the sources of macroplastic to rivers and the mechanisms controlling fate and transport is essential to identify and tailor measures that can effectively reduce global plastic pollution. Several guidelines exist for monitoring macroplastic in rivers; yet, no single method has emerged representing the standard approach. This reflects the substantial variability in river systems globally and the need to adapt methods to the local environmental context and monitoring goals. Here we present a critical review of methods used to measure macroplastic flows in rivers, with a specific focus on opportunities for methods testing, harmonisation, and quality assurance and quality control (QA/QC). Several studies have already revealed important findings; however, there is significant disparity in the reporting of methodologies and data. There is a need to converge methods, and their adaptations, towards greater comparability. This can be achieved through: i) methods testing to better understand what each method effectively measures and how it can be applied in different contexts; ii) incorporating QA/QC procedures during sampling and analysis; and iii) reporting methodological details and data in a more harmonised way to facilitate comparability and the utilisation of data by several end users, including policy makers. Setting this as a priority now will facilitate the collection of rigorous and comparable monitoring data to help frame solutions to limit plastic pollution, including the forthcoming global treaty on plastic pollution.

Do urban rivers in the amazon coast trap macroplastic?

Amazon Rivers are important sources of macroplastic that enter the oceans. The estimated macroplastic transport is still inaccurate as hydrodynamics are not considered and data are not collected in situ. The present study shows the first quantification of floating macroplastics at different temporal scales, and an annual transport estimate through urban rivers in the Amazon: the Acará and Guamá Rivers, which discharge into the Guajará Bay. We conducted visual observations of macroplastics (>2.5 cm) in different river discharges and tidal stages, and we measured current intensity and direction in the three rivers. We quantified 3481 floating macroplastics, which varied according to tidal cycle and seasonality. Although connected to and affected by the same tidal regime, the urban estuarine system had an import rate of 12 ton.y^-1 through the Guamá River and an export rate of 21.7 ton.y^-1 of macroplastics through the Guajará Bay, affected by local hydrodynamics.

Density variability of COVID-19 face mask litter: A cautionary tale for pandemic PPE waste monitoring

Despite the requirement for data to be normally distributed with variance being independent of the mean, some studies of plastic litter, including COVID-19 face masks, have not tested for these assumptions before embarking on analyses using parametric statistics. Investigation of new data and secondary analyses of published literature data indicate that face masks are not normally distributed and that variances are not independent of mean densities. In consequence, it is necessary to either use nonparametric analyses or to transform data prior to undertaking parametric approaches. For the new data set, spatial and temporal variance functions indicate that according to Taylor's Power Law, the fourth-root transformation will offer most promise for stabilizing variance about the mean.

The halophyte Cakile maritima Scop. 1772 as a trap of plastic litter on the Moroccan coast

Some plant communities of coastal dunes may affect the magnitude and distribution of litter on the ecosystem. In this study, the aim is to assess the aptitude of the halophyte Cakile maritima Scop. 1772 to be a trap and sink of plastic litter on the Moroccan Atlantic coast. Overall, a significant difference was noted between plastic litter trapped in C. maritima patches (1173 items) and control plots (502 items). Food containers and ropes were the most common trapped items. Shoreline and recreational activities, followed by dumping and ocean/waterway activities are the main sources of the trapped plastic items. The findings suggest the expansion of the cleaning operations to include coastal dunes, the need to change behavior among beachgoers in regard to food plastics disposal, as well the control of C. maritima distribution in the study area, and similar plant species in other regions.

Anthropogenic litter on the macrotidal sandy beaches of the Amazon region

Coastal zones, which are strategic points of considerable importance to the tourism industry, are among the environments most affected by anthropogenic debris. Thus, it is crucial to monitor and implement management programs to provide immediate solutions. Here, we aimed to evaluate anthropogenic litter along 21 macrotidal sandy beaches in the Amazon region. Indices and multivariate statistical analyses were used to identify spatial patterns of pollution, as well as sources and lifetime of the items. A total of 20,286 items were collected, with an average density of 0.19 items/m² and a predominance of plastics. Litter was associated with tourist and recreational activities. The lifetime of most items was <1 year. All beaches had intermediate levels of pollution. The analyses identified varying patterns of anthropogenic litter related to the cleaning frequency and waste item typologies. In conclusion, pollution of macrotidal beaches in the Amazon region is an emerging problem that requires measures to prevent and mitigate the impacts on this ecosystem and to reconsider the form of production and consumption of plastic waste.

Macroplastic transfer dynamics in the Loire estuary: Similarities and specificities with macrotidal estuaries

The quantification of macroplastic fluxes transferred by rivers toward the pelagic environment requires a better understanding of macrodebris transfer processes in estuarine environments. Following the strategy adopted in the Seine estuary, this study aims to characterize macroplastic trajectories in the Loire estuary. Between January 2020 and July 2021, 35 trajectories were monitored using plastic bottles equipped with GPS-trackers. With total travelled distances between 100 m and 103.6 km, trajectories show great spatiotemporal variability. The various forcing factors (macroplastic buoyancy, estuaries tidal and hydrometeorological conditions, geomorphology and vegetation) lead to chaotic trajectories, preventing accurate predictions in macroplastic transfer and storage/remobilization dynamics. In the Loire estuary like in the Seine one, no tracked bottle reached the Atlantic Ocean. It confirms that macrotidal estuaries under temperate climates constitute accumulation zones and slow pathways for macroplastics, but raises question on the real fluxes transferred from continental areas to oceans.

Are tropical estuaries a source of or a sink for marine litter? Evidence from Sabaki Estuary, Kenya

Litter surveys were carried out in August and September 2020 to determine the contribution of Sabaki River and estuary in modifying the quantities of litter entering the oceans. The river discharged 0.035 items m^-3s ^-1 translating to an estimated annual litter flux of between 6,622,560 and 614,952,000. The surveys in the estuary revealed that plastics contributed 90.8% of the total litter. Wet and dry zones had mean litter accumulation rates of 2.7 ± 1.1 and 4.4 ± 3.5 items m^-1 day^-1 respectively. 69.8% and 77.4% of branded litter were of Kenyan origin and food packaging material respectively. The litter turnover was slightly higher in the dry beach zone compared to the wet zone with a Whitakker Beta diversity of 0.36 and 0.33 respectively. Sabaki estuary acted as a sink for litter during flooding (through burial) and as a source (through exposure of buried litter due to wind and rain action).

Plastic pollution: A focus on freshwater biodiversity

Plastics are dominant pollutants in freshwater ecosystems worldwide. Scientific studies that investigated the interaction between plastics and freshwater biodiversity are incipient, especially if compared to the marine realm. In this review, we provide a brief overview of plastic pollution in freshwater ecosystems around the world. We found evidence of plastic ingestion by 206 freshwater species, from invertebrates to mammals, in natural or semi-natural ecosystems. In addition, we reported other consequences of synthetic polymers in freshwater ecosystems-including, for instance, the entanglement of animals of different groups (e.g., birds). The problem of plastic pollution is complex and will need coordinated actions, such as recycling programs, correct disposal, stringent legislation, regular inspection, replacement of synthetic polymers with other materials, and ecological restoration. Current information indicates that the situation in freshwater ecosystems may be as detrimental as the pollution found in the ocean, although highly underappreciated.

Assessment of plastic pollution in the Bohai Sea: Abundance, distribution, morphological characteristics and chemical components

Plastics are globally distributed in oceans and can pose a threat to the environment and organisms. In this study, plastic pollution in surface water and sediments of the Bohai Sea was assessed based on plastic abundance, distribution and characteristics (shape, polymer, size and color). Water and sediment samples were collected across the sea using a plankton net (330 μm) and a grab sampler, respectively. The following conclusions were reached. 1) In surface water, large plastics were less abundant (0.14 items/m³) and showed less diverse characteristics than microplastics (0.79 items/m³) but did not significantly differ in spatial distribution. 2) Microplastics in water were more abundant (1.95 items/m³) with more diverse characteristics in Liaodong Bay than in other regions of the sea (0.26-0.59 items/m³). Plastic waste from highly concentrated agricultural, industrial and fishery activities could make large contributions to microplastics in Liaodong Bay. Additionally, low hydrodynamics and long distance to Bohai Strait are unfavorable for diffusion of particles, facilitating the retention of microplastics and increasing the abundance in this bay. 3) Microplastics in sediments were smaller in terms of dominant sizes (<0.5 mm) with less diverse characteristics than particles in water (0.5-1.5 mm). Specifically, fragments, foams and lines dominated among the microplastics in water, whereas fibers and fragments were dominant particles in sediments; alkyd resin, polyethylene, polystyrene and polypropylene (PP) predominated among the particles in water, but rayon, cellulose and PP were dominant particles in sediments. 4) Neither abundance nor size of microplastics in the two media was proportionally correlated and showed low similarity indexes of polymer (0.16), shape (0.29) or color (0.38). This could be related to mismatch in spatiotemporal distributions and variations in the characteristics, fate and behavior of microplastics in the two media. The findings provide knowledge for tracing the sources of plastics in the Bohai Sea.

A novel facet of the impact of plastic pollution on fish: Silver croaker (Plagioscion squamosissimus) suffocated by a plastic bag in the Amazon estuary, Brazil

On December 23rd, 2020 in the Marajó Bay, Amazon estuary, we found a specimen of Plagioscion squamosissimus floating dead and choked and suffocated by a plastic bag. Here, we presented images of record and discuss the rarity and factors that may be involved in this to date unreported plastic-animal interaction for bony fishes.