Plastic pollution is an emerging environmental problem, as it can negatively affect ecosystems and biodiversity and cause socio-economic damage. The plastic global mass production, disposal and mismanagement have resulted in the accumulation of immense amounts of plastic litter in aquatic environments, with sizes ranging from macro- to nano-plastics. Once plastics enter the aquatic systems, they can be degraded into smaller fragments, be entangled in living organisms, aggregated with natural colloids, settled into the sediment, or become resuspended and transported back out of the system. The increasing concentration of plastics into aquatic systems demands investigating the transport, fate, and impacts of plastic pollution, in particular in ecosystems that are key for biodiversity support. Aquatic ecosystems are vulnerable to the accumulation of plastic waste due to the location of dense human populations, especially along the coasts, with inputs of plastics from rivers and debris washed ashore from the open ocean. In particular, coastal habitats such as seagrass meadows, salt marshes, mangrove forests or oyster and coral reefs are known to enhance trapping, deposition or burial of suspended particles through attenuation of the current and wave energy, through stabilisation of the sediment from resuspension or though their filtering capacity. In the last few years there has been a growing interest about the role of these canopy-forming and biogenic habitats in plastic trapping, leading to research works on the abundance and characterisation of plastics in them, as well as in the biophysical factors underlying their plastic retention capacity. In fact, recent studies evidenced that these habitats trap plastic particles within their biogenic structures, making them microplastic sinks or hotspots of plastic accumulation. This session aims to gather ecological research studies on the assessment and quantification of plastic pollution, from macro- to nano-plastics, in different aquatic biogenic habitats, as well as strategies to reduce and manage plastic litter in these areas. We welcome both observational, experimental, and modelling works elucidating the role of aquatic systems on the dynamic and accumulation of plastics.
Lead Organizer: Gema Hernán, Mediterranean Institute for Advanced Studies (gemahernanm@gmail.com)
Co-organizers:
Julia Máñez-Crespo, Mediterranean Institute for Advanced Studies (julia.manez@gmail.com)
Carmen B. de los Santos, CCMAR-Centre of Marine Sciences (cbsantos@ualg.pt)
Presentations
10:30 AM
Intraspecific genetic lineages of intertidal marine mussels show behavioural divergence when exposed to microplastic pollution (5500)
Primary Presenter: Lorenzo Cozzolino, CCMAR, Centro de Ciencia do Mar - University of Algarve (lorenzo_cozzolino@hotmail.it)
Worldwide, microplastics (MPs) pollution has numerous negative implications for marine biota. An extensive and ever-increasing number of studies have emphasized the distinct responses of different species to plastic pollution. Most studies have, however, assumed that species respond to plastic pollution uniformly as ecologically and physiologically homogenous entities, while ignoring intraspecific diversity. Here, we used two key marine ecosystem engineers, the Mediterranean mussel Mytilus galloprovincialis and the South African mussel Perna perna, as model species to test for the effects of plastic contamination - both in the form of MPs ingestion and microplastic leachates (MPLs) - on distinct genetic lineages of each of the two species. We showed that when exposed to MPLs, Mytilus galloprovincialis belonging to the Atlantic lineage move and aggregate significantly less than conspecifics of the Mediterranean lineage. In addition, we assessed MPs ingestion in the Eastern and Western lineages of the brown mussel Perna perna sampled at sites where the two lineages overlap in their distribution along the South African shores. Our results show that plastic pollution can have different effects on distinct genetic lineages of one species and argue for consideration of intraspecific diversity to ensure a comprehensive understanding of the effects of plastics on biodiversity.
10:45 AM
RIVERBANK MACROPLASTICS STOCKS FLUSHED TOWARDS THE INDIAN OCEAN DURING MAJOR FLOODING IN SOUTH AFRICA’S UMGENI RIVER (6911)
Primary Presenter: Tadi Gutsa, University of Kwazulu-Natal (217081368@stu.ukzn.ac.za)
Rivers are major contributors of plastic waste entering the oceans. The Umgeni River in Kwazulu-Natal, South Africa, runs through the densely populated city of Durban, with 3.5 million inhabitants and models estimate 400 tons of plastic waste annually emitted into the Indian Ocean. The banks of the Umgeni River are lined with plastic waste accumulations, derived from accidental, intentional, and natural accumulation. This study presents the use of Unmanned Aerial Vehicles (UAVs) and hydro-meteorological measuring sensors in the catchment to (1) identify, monitor, and quantify macroplastic waste hotspots along the Umgeni River; and (2) investigate the influence of hydro-meteorological factors driving the spatio-temporal evolution of the hotspots. Preliminary findings from two of the eleven monitored hotspots indicate a gradual build-up of surface area impacted by plastic pollution by 40–50% from January–April 2022. In April 2022, alone, a sharp decrease of –40–60% was recorded following a major flood event in Durban, when most parts of the city received rainfall between 200–400 mm within 24-hours (average April rainfall: 33.1 mm). Post flooding the surface area impacted by plastic pollution begins to gradually build-up again by 40–60% between April–June 2022. The findings suggest that macroplastics riverine transport and ocean emissions are considerably influenced by the flushing of waste stocks in discrete hydro-meteo events. Such information will help refine temporal resolution of riverine pollution contributions to the receiving coastal environments. The mapping of waste hotspots and the prediction of their mobilisation into the river supports policymakers in planning and timing to mitigate environmental pollution and protect water infrastructure from flood-exacerbating debris-induced waterway blockage.
11:00 AM
Transport and storage of anthropogenic particles in mountain freshwater ecosystems (6934)
Primary Presenter: Helena Guasch, Centre d'Estuds Avançats de Blanes, Consejo Superior de Investigaciones Científicas (helena.guasch@ceab.csic.es)
Plastic pollution is a worldwide environmental problem, which affects all natural habitats, even in the most pristine areas. The PLASTICØPYR project explored the influence of mountain tourism on plastic transport and storage in rivers. The project has developed unique survey protocols for plastic quantification and identification. The surveys that were conducted in areas located in the Pyrenees of Catalonia, Andorra and France showing different levels of human impact, mainly associated with presence of ski resorts, residential and hiking areas. Here, we will present the results from these surveys, which show the link between tourism and plastic pollution in these Pyrenean fluvial ecosystems. We have found that i) riparian zones act as transient storage of large particles (>5 mm) with up to 36 Kg/ha in the vicinities of ski resorts); ii) riverbed and biota accumulate smaller particles (<5 mm), with a notable occurrence in the gut contents of trout; and iii) plastic downstream transport in the water column follows a similar pattern than plastic pollution in the riparian zone, reaching up to 3 g plastic/h in urban areas. Results from our holistic approach (sampling of different particle-sizes in riparian and stream habitats) demonstrate and describe how mountain tourism contributes to plastic pollution and confirm that fluvial ecosystems, even those located in headwaters at high elevations, are remarkable sources and sinks for plastic particles.
11:15 AM
HIGH MACROPLASTICS TRANSFER PROBABILITY FROM THE OZAMA AND ISABELA RIVERS TO THE CARIBBEAN (6953)
Primary Presenter: Rafael Garcia, Instituto Tecnologico de Santo Domingo (rafael.garcia@intec.edu.do)
Due to mismanagement, large quantities of macroplastics are transported through rivers toward the oceans. In this research, floating debris transport through the final 20 kilometers of the urban section of the Ozama-Isabela River water network (Santo Domingo, Dominican Republic) and into the Caribbean Sea was investigated. This study intended to mimic macroplastic transport in the watershed by deploying and analyzing the travel routes of 68 floating GPS drifters (cylinder, 10 x 8 cm, 500 g, 0.7 g cm-1). The drifters were deployed in three seasonal batches in 2022 (March – dry, August – wet-hurricane, December – wet-dry) and covered five tributary ravines (cañadas) and ten locations on the main rivers. One-third of all deployed drifters moved through the river network and out to sea. Of the drifters deployed in the main rivers alone (n = 53), 40%–90% transferred to sea, depending on the season. The mean main river transition time before emission to the sea was only six days. Four out of 15 drifters deployed in tributary ravines were flushed to sea – they took 20 to 50 days to reach the Caribbean. Mobility and river-ocean transition probability is associated with rainfall intensity during drifter lifetime. Ocean emission probability was roughly halved within 10 km deployment distance from the river mouth during the experimental period (R2 = 0.5; p < 0.005). Seaborne drifters moved westwards in the Caribbean current, stranding along the coast of Hispaniola Island. Although the investigated river length is relatively short, the results are surprising, considering the presence of structural impediments and riverbank vegetation. The presented data contrasts study findings from more tidal estuaries where the river mouth is regarded as a potential debris sink. With this study, we aim to strengthen macroplastic transport modeling in river watersheds to enhance macroplastic emission estimates.
11:30 AM
DETECTION AND FLUX ESTIMATION OF MACROPLASTICS IN THE OZAMA RIVER USING FIXED BRIDGE CAMERAS (6963)
Primary Presenter: Winston Gonzalez, Instituto Tecnologico de Santo Domingo (INTEC) (winston.gonzalez@intec.edu.do)
Plastic waste has become a main pollutant of riverine and marine environments, with the former acting as a critical route from land to sea. The Ozama River located in the >3 million-inhabitant city of Santo Domingo, Dominican Republic, is considered one of the largest contributors of terrestrial macroplastic waste to the Caribbean Sea. Modeled emission estimates show high uncertainty due to the lack of consistent, long-term field data. Mounted monitoring cameras (n = 8) across two main river bridges at 5.5 km and 2.2 km upstream of the river mouth validated current flux and emission models of macro debris (>5 cm). Analysis of 380,000 images collected over 383 days starting February 2022 shows a 2-fold increase and a 1.5-fold increase in debris concentrations and mass fluxes, respectively, in the downstream direction. The increased debris detection downstream is associated with the influx from riparian ravines (cañadas) and illegal waste dumping along the stream. A daily average of 0.9 tons of anthropogenic "trash" flux was detected at the downstream location, resulting in over 300 tons and 10 million macro particles annually. This mass flux is at the low range of previous model estimates. The mass flux of organic materials, such as water hyacinths, was up to ten times higher than the trash fluxes. The data shows a positive correlation between organic and non-organic waste peaks, reflecting the findings of previous studies. Future data can support determining uncertainty and offers an assessment of discrete environmental and anthropogenic peak events.
11:45 AM
Marine Plastisphere Biofilm Community Progression in a Mid-Latitude Tidal Sub-Estuary (7397)
Primary Presenter: Gregory Joern, Old Dominion University (gjoer001@odu.edu)
Plastics are a new modification to the environment solely caused by humans. It is important to understand not only how plastics will possibly affect ecosystem functioning, but also how the ecosystem will influence the fate of plastics. In the ocean, buoyant microplastics are frequently found at the surface and within the water column, and biofilm formation may influence plastic’s buoyancy and distribute plastic to deeper layers. This study incubated high density polyethylene plastics in-situ in an estuary of the Chesapeake Bay & in-vitro, and examined biofilm formation through ATP, pigments, silica, and taxonomic composition of attached microbes using genomics and lipidomics. Even with six months of undisturbed nutrient-enriched in-vitro growth, biofilm accumulation did not induce negative buoyancy in a single plastic particle (6.2 x 0.48 mm2). Plastic sheets in situ incubated over a seven-week period accumulated a thick biofilm including abundant pennate diatoms that contain biogenic silica and thus contribute to ballast. However, a model based on the measured maximum accumulated silica and varying plastic thicknesses suggests that not even a plastic sheet as thin as a plastic bag, and bio-fouled on both sides, would become negatively buoyant; and the same plastic as thin as cling film would become negatively buoyant in freshwater only and not in seawater. Our results, overall, suggest that biofilms alone are unlikely to significantly influence the buoyancy of marine plastic debris.
SS090B Plastic Pollution in Aquatic Systems: The Role of Biogenic Habitats in the Dynamics and Accumulation of Plastics
Description
Time: 10:30 AM
Date: 5/6/2023
Room: Sala Ibiza A