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
06:30 PM
Marine Plastic Debris concentration and distribution in the sand column of three different beaches located on the island of Oahu in Hawaii (4919)
Primary Presenter: Astrid Delorme, Center for Marine Debris Research, Hawai'i Pacific University, The Ocean Cleanup Foundation, Université Clermont Auvergne, CNRS, Clermont Auvergne INP, ICCF (astrid.delorme@sigma-clermont.fr)
Recent global plastic pollution models predict that two-thirds of the plastic mass released from land into the ocean since the 1950s is likely to have stranded around the world’s shoreline. Yet, our knowledge about the degradation, burial and transportation of beached marine plastic debris (MPD) remains limited and little is known about the exact capacity of beaches to store and retain MPD. The beaches of Hawaii accumulate high amounts of MPD given their location and proximity to the North Pacific Subtropical Gyre, in which the floating plastic accumulation is known as the Garbage Patch. However, research on beached MPD has focused mostly on sampling at the surface and near surface of the beach (<10 cm depth). Here, we present the first objective of the STORAGE project: “predicting the fate of plaSTic On beaches by theiR 3D-distribution and weAtherinG processes”, which aims to fill in current knowledge gaps in the global monitoring of MPD in coastal environments and with a particular focus on the role of beaches in the fate of MPD (transportation, storing, and transformation). We sample MPD (with sizes > 0.5 mm) for each 10 cm layer of sand (in 60x60 cm quadrats), down to 1 meter depth, which are categorized, measured and counted through the use of an image segmentation model. A random subset of sampled MPD is analysed further under Infrared Spectroscopy for polymer identification. For the different 10 cm layers we observe a range of concentrations at the different depths with the number of MPD particles ranging from 0 to over 1000 particles per 10 cm layer (36 litre of sand) and observe significant differences in MPD distribution in the sand column between the three selected beaches. To aid our understanding of the role of beaches in the fate of MPD, we are also monitoring the beach dynamics by assessing the sand accretion and erosion rates through long-term timelapse imaging.
06:30 PM
RISE VELOCITY OF BIOFOULED POLYOLEFINS IN A SEAWATER TANK EXPOSED TO NATURAL CONDITIONS IN HAWAIʻI (5583)
Primary Presenter: Sarah-Jeanne Royer, The Ocean Cleanup (sarah-jeanne.royer@theoceancleanup.com)
Floating plastic is ubiquitous at the surface of the ocean, but the transport mechanisms associated with the effect of environmental parameters including the presence of a biofilm to the polymers are very limited. Biofilm affects the object’s buoyancy and its density, hence impacting the distribution and sinking behaviors of plastics in the marine environment. Here, we assess the effect of biofouling on the rise velocity of positively buoyant polyolefins in the water column in environmentally relevant marine conditions. To establish whether biofouling influences the transport of plastics and enhances their removal from surface waters, we conducted a long-term monitoring experiment within a flow-through aquaculture system on Oʻahu, Hawaii using low-density polyethylene, high-density polyethylene (HDPE), and polypropylene of different sizes and shapes (films, rods, and cubes). Physico-chemical variables of the polymers were measured on a weekly and monthly basis, while environmental parameters such as light exposure, temperature, and chl a were monitored at higher resolution (days to minutes). Preliminary results show that HDPE and small size film has the potential to sink faster and that the surface area to volume ratio is the parameter influencing most the rise velocity when considering the different shapes and sizes. This study offers one of the first empirical data to incorporate into numerical models to assess the effect of biofouling on plastic rise velocities and helps predict the fate and sinks of positively buoyant plastics in the ocean.
06:30 PM
MARINE LITTER AND PLASTIC POLLUTION IN THE NW MEDITERRANEAN, THE CASE OF THE CATALAN COAST (6433)
Primary Presenter: Eve Galimany, Institut de Ciències del Mar (ICM-CSIC) / Institut Català de Recerca per a la Governança del Mar (ICATMAR) (galimany@icm.csic.es)
The Mediterranean Sea has registered great abundances of benthic marine litter (ML). The seafloor is often where it accumulates, an area shared with the activity of bottom trawlers, which can accidentally catch the litter from the seafloor, in strategies named Fishing for Litter (FFL). Thus, this study describes, quantifies and maps the ML caught by bottom trawlers along the Catalan coast (NW Mediterranean Sea). The litter was obtained from 305 hauls performed during three years (2019-2021) from 9 different ports at 3 depth strata covering from 20 to 700 m. In the laboratory, the ML was weighted and classified in six different categories (metal, plastic, rubber, textile, wood, and other waste). ML was present in 97 % of the hauls, which composition varied according to zone, port and depth, with the highest densities found in highly urbanized areas (13.75 ± 3.25 kg km-2), which mainly contained plastics (74,3 %). The port of Barcelona had the highest presence of plastics (23.62 ± 6.49 kg km-2), mainly wet wipes. Regarding depth, the continental shelf had the highest density of ML, with 12.24 ± 2.40 kg km-2. The effect of different ML sources was tested in order to evaluate spatial distribution of ML in the Catalan seafloor. To conclude, the bottom trawl fleet of the Catalan coast has the potential to remove 237 ± 36 t of marine litter yearly. Therefore, FFL initiatives should be part of a multidisciplinary approach to tackle marine litter, which must include prevention, monitoring, and cleaning actions.
06:30 PM
MICROBIAL COLONIZATION AND FUNCTION OF BIOFILMS DEVELOPING ON PLASTICS AND BIOPLASTICS IN A MOUNTAIN STREAM ECOSYSTEM (6512)
Primary Presenter: Mar Oliva-Albert, University of Girona (u1952356@campus.udg.edu)
Mountain river ecosystems naturally receive particulate organic materials such as leaf litter, wood and branches from the riparian vegetation, which are substrata and organic matter source for microbial communities. Human activity may drive a further input of particulate organic materials such as plastic in these ecosystems, as well as bioplastics which have emerged as an alternative to plastics. We aimed to analyze the differences in biomass and function of microorganisms colonizing plastics and natural materials in a mountain river ecosystem. Samples of 2 natural materials (leaves and wood), 2 bioplastics (PHA, PLA), and 2 plastics (PE, PP) were immersed in the Torrent de Concròs (1400 m.a.s.l., eastern Pyrenees), and collected after 120, 202, 316 and 383 days. Microbial biomass and autotrophic and heterotrophic functions (net primary production, respiration, extracellular enzyme activities, and nutrient uptake) were analyzed together with weight loss (i.e. decomposition rate). We found higher values of microbial biomass, β-glucosidase, phosphatase and lipase activities, and weight loss in natural materials. Phenol-oxidase activity did not present clear differences between natural and non-natural materials, which could mean that this activity plays a role in the degradation of non-natural materials. Results suggest that higher heterotrophic activity and biomass enhances the decomposition of natural materials while autotrophic colonization of plastics and bioplastics suggest these materials are behaving more as an inert substrata than as an organic matter source.
06:30 PM
MICROPLASTICS IN A MACRO LAKE: AN INVESTIGATION INTO THE OCCURRENCE OF MICROPLASTICS IN A LARGE OLIGOTROPHIC LAKE (7059)
Primary Presenter: Sandra Nierzwicki-Bauer, Rensselaer Polytechnic Institute (nierzs@rpi.edu)
Microplastic contamination has been well documented in freshwater lakes and rivers over the last decade. A three-year observational study was completed to determine the extent of microplastic occurrence in Lake George, a large oligotrophic lake in upstate New York, USA. Microplastics were quantified in samples collected from the Lake’s surface using a manta net, throughout the water column using a plankton net, from lake sediments and in benthic organisms that inhabit the lake. Microplastic densities in lake surface, water column and sediment samples were comparable to abundances observed in published studies in nearby water bodies. Native and invasive bivalves were dissected to determine if microplastics were present. Minimal plastic contamination was observed in the native mussel species (Elliptio complanata) whereas up to twenty microplastic particles were observed in a dissected invasive Asian clam (Corbicula fluminea). Weekly analyses of microplastics in invasive clams identified a strong seasonal component to the prevalence and abundance of microplastics observed in these organisms. These data have identified that microplastic contamination is present in this large oligotrophic lake and that plastics have entered the benthic organisms.
06:30 PM
EPIGEAL STRUCTURAL COMPLEXITY MEDIATES SEAGRASS MEADOW MICROPLASTICS SINK CAPACITY (7158)
Primary Presenter: Silvia Oliva Pérez, Universidad de La Laguna (silviaolivaperez@gmail.com)
Microplastic (MP) particles spread all over the marine trophic chain, latently threatening ecosystems’ and human health. To tackle the problem, the traits that favor their accretion across habitats must be identified. Seagrass meadows are key ecosystems of soft bottoms worldwide. Their leaves trap particles from the water column, favoring their burial into the sediment. Several studies have confirmed the presence of MP in these meadows’ sediments, but less light has been shed on the features that mediate their accrual. Here we studied the MP accumulation mediating role of seagrass epigeal structural complexity of an intermediate-sized species. Two replicated habitat types (vegetated, unvegetated-UV) and levels of structural complexity (high-HC, low-LC) were assessed in natural meadows (Canary Islands). Sedimentary MP abundance was determined from cores of superficial sediment. We found MPs in the sediments of all studied meadows, covering diverse shapes, sizes and colors, being the 1-2 mm transparent fibers the most profuse. MP abundance in the sediments inside HC meadows significantly exceeded that of their abutting UV sediments. MP abundance inside LC meadows equaled that of their abutting UV sediments, significantly exceeding that of UV sediments abutting HC meadows. Our results evince that epigeal structural complexity of seagrass meadows mediate their MP sink capacity. HC meadows function as enhanced sinks when compared to UV sediments. Conversely, LC meadows lack this boosted filtering capacity, and their abutting UV sediments function as enhanced MP sinks instead.
SS090P Plastic Pollution in Aquatic Systems: The Role of Biogenic Habitats in the Dynamics and Accumulation of Plastics
Description
Time: 6:30 PM
Date: 6/6/2023
Room: Mezzanine