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
08:30 AM
The role of vegetated coastal systems in the accumulation of microplastics (6008)
Primary Presenter: Gema Hernan, Mediterranean Institute for Advanced Studies-CSIC UIB (gemahernanm@gmail.com)
Microplastic (MPs, plastics <5 mm) contamination of the marine environment has become one of the world’s main environmental concerns, not only because of their continuous accumulation but also due to their serious threats posed to the ecosystems. This is the first review to present the current state of MPs pollution in three vegetated coastal systems: mangroves, seagrasses and salt marshes. These habitat-forming ecosystems are known to enhance deposition of suspended particles, including MPs. We aim to provide a more integrated view of MPs pollution specially including (i) geographical distribution of studies; (ii) MPs pollution by mean accumulation in the different environmental compartments in each ecosystem; (iii) factors influencing MPs distribution: vegetation, core depth and anthropogenic pressure and (iv) MPs characteristics: size, colour and polymer composition. We found an unequal geographic distribution with most studies performed in the Northern hemisphere. Likewise, we found a significant difference in the spatial distribution of MPs attributed to different levels of anthropogenic activities and natural factors. Fibers and fragments are the dominant form of MPs found in theses systems and blue, black and transparent are the most abundant colour. Polypropylene was the most abundant polymer, followed by polyethylene and polystyrene. The results of this study highlight the importance that vegetated coastal ecosystems have in MP retention and sink.
08:45 AM
Characterizing the retention capacity of microplastics in a seagrass meadow as a function of hydrodynamics and shoot density (6891)
Primary Presenter: Julia Máñez-Crespo, IMEDEA (julia.manez@gmail.com)
Seagrass meadows provide a wide variety of ecosystem services around the world, making them a highly valuable ecosystem throughout coastal areas. Amongst them, are their contribution to coastal sediment stabilization and their role as carbon sinks. Furthermore, their ability to act as a physical filter of particles in suspension, generally composed of organic matter, is critically important to maintain associated food webs. These services are the result of seagrasses being able to modify coastal hydrodynamics as a function of their physical attributes, such as biomechanical properties, morphology, density. Their capacity to attenuate water movement and enhance particle trapping could imply that seagrass meadows may also act as "sinks for plastics”, and recent studies have highlighted the role of plant density in determining microplastic trapping under unidirectional flow conditions. Here we investigated for the first time the role of wave, currents, and their interactions on the capability of microplastic retention by eelgrass Zostera marina under different shoot density conditions. As seagrass beds act as a physical filter for microplastics and favour their sedimentation, these results will have important repercussions on the biodiversity and in future management and mitigation strategies of plastic waste.
09:00 AM
MICROPLASTIC TYPE INFLUENCES FATE IN VEGETATED WETLANDS (4990)
Primary Presenter: Hayley McIlwraith, Plymouth Marine Laboratory & University of East Anglia (hamc@pml.ac.uk)
Coastal areas are prone to plastic accumulation due to their proximity to land based sources. Coastal vegetated habitats (e.g., seagrasses, saltmarshes, mangroves) provide a myriad of ecosystem functions, such as erosion protection, habitat refuge and nursery grounds, and carbon storage. The biological and physical factors that underlie these functions may provide an additional benefit: trapping of marine microplastics. While microplastics occurrence in coastal vegetated sediments is well documented, there is conflicting evidence on whether the presence of vegetation enhances microplastics trapping relative to bare sites. Moreover, the factors that influence the likelihood of microplastic trapping remain understudied. We aimed to investigate how vegetation structure and microplastic type influences trapping in a simulated coastal wetland. Through a flume experiment, we measured the efficiency of microplastic trapping in the presence of two types of vegetation – branched and grassy, and tested an array of microplastics that differ in shape, size, and polymer. We show that the presence of vegetation did not affect the number of microplastics trapped but did affect location of deposition. Microplastic shape, rather than polymer, was the dominant factor in determining whether microplastics were retained in the sediment or adhered to the vegetation canopy. The outcome of this study enriches our understanding of coastal vegetation as a microplastics sink and that differences among microplastics informs where they are most likely to accumulate within a biogenic canopy.
09:15 AM
Ingestion of microplastics by fishes in estuarine habitats: how different feeding strategies and trophic pathways influence exposure to microplastics (4851)
Primary Presenter: Gorka Sancho, College of Charleston (sanchog@cofc.edu)
Estuarine marshes have been shown to trap microplastic particles. The ingestion of microplastics by estuarine fishes varies greatly depending on the feeding strategies of different fish species. We analyzed trophic pathways leading to microplastic ingestion by comparing microplastic loads in intestinal tracts from estuarine fishes in South Carolina (USA). Fibers were the most common type of plastic in all species, but plastic fragments, foam and tire wear particles were also abundant. Benthic feeding fishes with distributions restricted to vegetated marsh habitats where microplastics are trapped had higher concentrations of microplastics than those inhabiting nearby sandy environments with higher water flow. Planktivorous fishes had the highest loads of microplastics of all fishes, including predatory and detritivore species. Planktivorous juvenile Atlantic Menhaden selectively feed on marine snow particulate aggregates showed the highest concentrations of ingested microplastics. Larger predatory shark species specie that mainly feed on Atlantic Menhaden showed higher microplastic concentrations than those targeting other prey species, indicating the potential key role that marine snow particles and Menhaden play in the trophic distribution of microplastics through estuarine food webs in the western Atlantic. In-depth spatial differences between fish species from our ongoing sampling efforts will be discussed to further characterize trophic pathways of microplastic and tire wear particle ingestion in estuarine ecosystems.
09:30 AM
BETWEEN TWO OCEANS: MARINE LITTER IN COLOMBIAN COASTAL ECOSYSTEMS (4640)
Primary Presenter: Miquel Canals, Universitat de Barcelona (miquelcanals@ub.edu)
Coastal ecosystems in Colombia open to the Pacific Ocean and the Caribbean Sea, a marginal basin of the Atlantic Ocean, providing critical environmental services to local communities. Mismanaged industrial and domestic waste pollutes and degrades such ecosystems. Here we present the preparatory works for marine litter research and the progress achieved so far by the Colombian Marine Environmental Quality Surveillance Network known as REDCAM. In 2017, joint working groups involving researchers and environmental authorities agreed on an inter-institutional roadmap for marine litter monitoring in Colombia. Five thematic axes were considered, namely research, monitoring, technical capacity building, communication and technical-regulatory articulation. Today, a country wide environmental database on marine litter pollution encompasses 40 beaches and 33 mangroves, together with case studies on impacts and risks from microplastics over lagoons, fishing resources and human well-being in vulnerable areas. The database shows how differences in geography, socioeconomics, climate and coastal dynamics amongst the two Colombian coasts determine ecosystem impacts. It shows, for instance, that the areas closer to large population centers are the most litter polluted. Colombia’s main challenges to address marine littering focus on: 1) increasing scientific knowledge in support of environmental management; 2) prevent pollution through awareness and education; 3) strengthen the political framework for environmental protection; and 4) reduce waste discharge from terrestrial and marine sources.
09:45 AM
REEF-BUILDING CORALS AND MICROPLASTICS: UNCOVERING THE RATES OF MICROPLASTIC INCORPORATION UNDER DIFFERENT POLLUTION SCENARIOS (6070)
Primary Presenter: Vanessa Tirpitz, Justus Liebig University (vanessa.tirpitz@bio.uni-giessen.de)
Reef-building corals have been found to incorporate microplastics (MP, i.e., plastic < 1 mm) in their tissue and skeleton after ingestion, adhesion, or overgrowth. This makes coral reefs important environmental sinks for marine MP. However, the mechanisms that affect incorporation rates remain poorly understood. Also, previous experimental studies on MP incorporation in corals have mostly focused on single MP types. To investigate the factors that influence MP incorporation in reef-building corals, we exposed the two species Stylophora pistillata and Pocillopora verrucosa to different pollution scenarios in two independent experiments: 1) distinct mixtures of MP, chosen to represent major anthropogenic pollutants (i.e., fragmented marine plastic waste, residues from the automobile sector, and artificial fibers), and 2) a standardized mixture of MP, chosen to represent the MP types mainly found in nature (PE, PVC, PS, PA, PP, and PET), applied at different concentrations (0, 0.1, 1, 10, and 100 mg/l). To quantify the incorporation of the MP, we separately dissolved coral tissue and skeleton, extracted MP, and standardized the numbers of MP found to the coral’s surface area and accreted skeleton. Our results show similar incorporation rates across different MP mixtures, suggesting the absence of selective processes for the incorporation of MP into the tissue and afterwards skeleton of reef-building corals. Overall, our results shed light on the processes underlying the incorporation of MP in reef-building corals under environmentally realistic scenarios.
SS090A Plastic Pollution in Aquatic Systems: The Role of Biogenic Habitats in the Dynamics and Accumulation of Plastics
Description
Time: 8:30 AM
Date: 5/6/2023
Room: Sala Ibiza A