The Science of Microplastics in the World Ocean - Poster Abstracts

Marine Debris Polymers on Main Hawaiian Island Beaches, Sea Surface, and Seafloor

Kayla C. Brignac^a,b, Melissa R. Jung^b, Cheryl King^c, Sarah-Jeanne Royer^d, Lauren Blickley^e, Megan R. Lamson^f, James T. Potemra^a, Jennifer M. Lynch^b,g

^aSchool of Ocean, Earth Science, and Technology, University of Hawaii at Manoa, Honolulu, HI, United States

^bCenter for Marine Debris Research, Hawaii Pacific University, Waimanalo, HI, United States

^cSharkastics, Kihei, HI, United States

^dInternational Pacific Research Center, University of Hawaii at Manoa, Honolulu, HI, United States

^eSwell Consulting, Paia, HI, United States

^fHawaii Wildlife Fund, Volcano, HI, United States

^gChemical Sciences Division, National Institute of Standards and Technology, Waimanalo, HI, United States

Polymeric differences of plastic debris were assessed across four compartments of the Main Hawaiian Islands (sea surface, windward beaches, leeward beaches, and seafloor) to better describe sources and fate. Plastic debris pieces (n=4,671) were collected from 11 beaches, three sea surface tows, and three seafloor dives. Fourier-Transform infrared spectroscopy identified the polymers of 3,551 pieces. Significant differences (p<0.05) in concentration, types, polymer composition, and weathering were found among four compartments. Windward beaches had one to two orders of magnitude more plastic pollution (g/m2) than leeward beaches, despite smaller human populations on windward sides. Sea surface and windward beaches were dominated by severely weathered, less dense floating polymers (polyethylene and polypropylene comprised 92.7% and 93.5% on average, respectively, of the total debris mass), while leeward beaches and the seafloor debris consisted of less weathered and more dense sinking polymers (e.g., 41.0% and 44.7% of total mass consisted of the sum of polystyrene, nylon, cellulose acetate, polyethylene terephthalate and additive-masked debris, respectively). These results are some of the first to provide evidence of polymeric stratification in the marine environment; and emphasize that the majority of marine debris in Hawaii is floating in from distant sources, rather than from Hawaii’s residents or tourists.

Polystyrene nanoplastics disrupt glucose metabolism resulting in cortisol-induced behavioral changes in larval fish

Nadja R. Brun, Patrick van Hage, Ellard, R. Hunting, Anna-Pavlina G. Haramis, Suzanne C. Vink, Martina G. Vijver, Marcel J. M. Schaaf, Christian Tudorache

Plastic nanoparticles originating from weathering plastic waste are emerging contaminants in aquatic environments, with a yet unknown toxicological profile. Due to their small size, the particles accumulate on dermal tissue and more importantly within organs such as intestine, gallbladder, and brain of fish. Recent studies suggest that internalized nanoplastics may disrupt processes related to energy metabolism. Such disruptions can be crucial for organisms during early stages of development and may ultimately lead to changes in behavior. Here, we investigated the link between polystyrene nanoplastic (PSNP)-induced signaling events and behavioral changes. Larval zebrafish exhibited PSNP accumulation in the pancreas, which coincided with a decreased glucose level. By using hyperglycemic and glucocorticoid receptor (Gr) mutant larvae, we demonstrate that the PSNP-induced disruption in glucose homeostasis concurred with increased cortisol secretion and hyperactivity in challenge phases. These results indicate a stress response activated through the hypothalamic-pituitary-interrenal (HPI) axis leading to disrupted energy metabolism and altered behavior. Our work sheds new light on a potential mechanism underlying nanoplastics toxicity in fish, suggesting that the adverse effect of PSNPs are at least in part mediated by Gr activation in response to disrupted glucose homeostasis, ultimately leading to aberrant locomotor activity.

Foraging strategy impacts plastic ingestion risk in seabirds

Aliya Caldwell, Dr. Jennifer Seavey, Dr. Elizabeth Craig

Plastic debris is a pervasive environmental challenge described as a world-wide crisis for marine life, and seabirds are particularly sensitive to the pollutant. Seabirds exhibit a range of foraging strategies, from generalist scavengers to specialist predators, which likely influence their risk of plastic ingestion. Our study evaluates this relationship using two congeneric seabirds, including a generalist species (the Herring Gull, Larus argentatus) and a more specialist species (the Great Black-backed Gull, L. marinus) nesting in the Gulf of Maine. Analysis for stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N) was used to evaluate interspecific differences in diet and niche size, while dietary samples were collected for analysis of plastic ingestion. Herring Gulls exhibited significantly larger isotopic niche size and displayed significantly higher rates of plastic ingestion than Great Black-backed Gulls (p-value<0.01), though the range of physical characteristics and relative size of plastics in the diet did not differ significantly.

Hydrophobic organic pollutants contaminating microplastics:
a monitoring study along the Italian coast of the central Adriatic Sea.

Capriotti M., Cocci P., Bracchetti L., Caprioli G., Mosconi G., Cottone E., Bovolin P., Palermo FA.

Microplastic issue is nowadays widely studied, otherwise a huge gap of knowledge exists on the real effects that plastic pollution can provoke. Chemical contaminants with hydrophobic nature tend to persist in the environment, to be adsorbed on surfaces (like microplastic surface) and to bioaccumulate inside organism tissues. Once ingested, plastic fragments can become vectors and sources of pollutants, which in turn may cause adverse health effects.
The aim of our study is to verify the presence of hydrophobic organic contaminants (HOCs) on the surface of microplastics collected from Italian coastal waters of Central Adriatic Sea and to investigate their potential metabolic effects by using in vitro bioassays. After microplastic classification (based on their dimension, shape and color), HOCs were analyzed through gas chromatography mass spectrometry (GC-MS). Polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), organophosphorus and organochlorine pesticides have been detected on the surface of microplastics from the majority of the sampling sites. In particular, pesticides with higher concentrations were pirimiphos-methyl and α-HCH. Among PCBs, the congeners 52, 95 and 138 were found in microplastics from each sampling area. Finally, it was estimated that the leaching of HOCs could increase lipid accumulation in 3T3-L1 adipocytes. Our data provide an additional proof of the vulnerability of Adriatic waters to microplastic contamination and highlight the need for further studies on health risks of the associated HOCs.

Understanding wind-driven vertical mixing of microplastics

Jessica Donohue¹, Kara Lavender Law¹, Ethan Edson², Kathryn Tremblay³

¹Sea Education Association, Woods Hole, MA

²Northeastern University, Boston, MA

³University of Massachusetts Dartmouth, School for Marine Science and Technology, Fairhaven, MA

How initially buoyant microplastics move vertically in the water column remains poorly understood.  The amount of floating microplastics measured at the sea surface varies depending on the wind speed (Kukulka et al. 2012). The energy from the wind mixes buoyant microplastics down to depths out of reach of the nets used to measure them.  Using measured wind speed and sea surface plastic concentrations, numerical models can predict the amount of plastic that has been mixed to depth. A key parameter in these models is the particle rise velocity – the speed at which a submerged particle would rise back to the surface if released at depth.

Utilizing a custom built rise velocity chamber, we carried out laboratory experiments measuring the rise velocity of individual microplastics collected at variable depths by Sea Education Association. We measured more than 200 particles of various forms, shapes and sizes, and evaluated the relationship between these particle characteristics and rise velocity. We also measured the mass of each particle, numerous 2-D size parameters using high-resolution scanned images, and polymer type using Raman spectroscopy. These results can advance our understanding of the depth distribution of microplastics in the upper ocean, improve existing numerical models, and lead to better predictions of surface microplastic concentrations in variable wind conditions.

Towards an improved understanding of the bioaccumulation and trophic transfer of microplastic particles

Todd Gouin

Observations of microplastic particles (MPs) in the environment and their detection in the stomachs and intestines of aquatic organisms have been reported since the early 1970s.  Given that the size of MPs is in the same size range of the particles and prey ingested by suspension-feeding invertebrates, an argument has been proposed regarding the potential of microplastic to be consumed by organisms low in the food-web, which could then facilitate transport of MPs to higher trophic-level organisms.  Whereas several studies continue to report microplastic in the gastrointestinal tract (GIT) of various species, strong evidence for a bioaccumulation process remains poorly understood for this methodologically challenging group of materials and there currently exists no systematic review that has been conducted to assess the issue related to the bioaccumulation of microplastic.  The ingestion of particles of varying sizes for aquatic organisms can vary from species to species and is strongly influenced by physiological and behavioural traits that are related to the size of the organism and its feeding strategy.  Consequently, some species may be susceptible to ingesting and accumulating MPs, however, there currently exists limited mechanistic understanding related to the potential of MPs to bioaccumulate.  The bioaccumulation potential of MPs thus represents a concern to regulators assessing the environmental risks of MPs, as their bioaccumulation may result in internal levels that can impact both individuals and populations.  The objective of this presentation is to summarize observations obtained from a critical review of the literature related to the biological uptake and bioaccumulation of MPs reported over the last 50 years in both aquatic and terrestrial species at all levels of biological organization.

Preliminary analysis of plastic ingestion by Great Shearwaters in the Gulf of Maine: 2007 - 2018

Christy Hudak, Center for Coastal Studies, chudak@coastalstudies.org

Anna Ruth Robuck, University of Rhode Island, anna_robuck@uri.edu

David Wiley, Stellwagen Bank National Marine Sanctuary, david.wiley@noaa.gov

Gwenyth Emery, University of Rhode Island, gwenyth.emery@gmail.com

Johanna Pedersen, Integrated Statistics, Inc., johanna.pedersen@noaa.gov

Joshua Hatch, Northeast Fisheries Science Center (NEFSC), joshua.hatch@noaa.gov

Researchers have been tracking plastic ingestion in seabirds for decades. Due to their high rate of plastic ingestion, seabirds are excellent indicators of plastic pollution. Great Shearwaters, Ardenna gravis, are one of the seabirds most prone to plastic ingestion. For example, between 2005 – 2008, 71% of the birds’ stomachs sampled along the U.S. East Coast contained plastics (n=17). Determining the plastic composition of the ingested plastics is critical in discovering the major sources of plastic in the environment. In this study, the chemical composition of archived plastic pieces in the stomach contents of Great Shearwaters taken from fisheries bycatch in the Gulf of Maine from 2007 - 2018, was identified using a Nicolet FTIR spectrometer with ATR correction. To date, 389 plastic pieces, with various shapes and sizes were analyzed. Plastic sources include carbon-carbon bonded polymers, such as polyethylene, polystyrene, and polypropylene to hetero chain polymers such as polyurethanes, used in flexible and rigid foams, sealants and coatings, and elastomers such as EPDM rubber. While low density polyethylene (LDPE) was attributed to 78% of the identifiable plastics pieces throughout the study period, two to six types of polymers were present each year. Less than 3% of the samples analyzed contained pieces with mixed polymers and additives. Based on the recycling grades, #1 through 6, 90% of the plastics analyzed from Great Shearwater stomachs were from recyclable plastics.

An inter-laboratory comparison for polymer identification of Hawaiian plastic marine debris:  What exactly comprises the debris?

Jennifer M. Lynch, National Institute of Standards and Technology
Ashok Deshpande, National Oceanic and Atmospheric Administration

Wanda Weatherford, Chevron Phillips Chemical Company

Rick Wagner, Chevron Phillips Chemical Company

Kayla C. Brignac, University of Hawaii

Kathleen Page, Hawaii Pacific University

Melissa R. Jung, Hawaii Pacific University

Davielle Drayton, Savannah State University

Nigel Lascelles, Florida A&M University

Dante Freeman, Savannah State University

Cheryl King, Sharkastics

Not all plastic marine debris is the same. Different polymers have different uses, waste management processes, environmental fates, oceanic transport, degradation rates, additive chemicals, affinities to sorb other environmental contaminants; thus, they may have different impacts on marine organisms. Therefore, identifying the polymer structure of marine debris is important. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR) is rapidly becoming the most common tool, but it is important to know and acknowledge its limitations. Here we compare its results with two other techniques. Samples were selected from 4000+ plastic marine debris items collected from Hawaiian Island beaches that had been tentatively identified using ATR FT-IR. Randomly selected items (n=88) were further analyzed using ATR FT-IR on two external sides in addition to the less weathered core. Evidence of multiple layers of different polymers was observed in 8% of the items, suggesting that multi-layer composites are a small proportion of debris along Hawaiian shorelines. Thirteen items each representing different polymers and 10 items that were unidentifiable by ATR FT-IR were analyzed by pyrolysis-GC/MS. Polymer identity agreed between the two methods for 88% of the items, but additional minor polymers were discovered in two items during data comparison. One was identified as polypropylene (PP) and polystyrene (PS) by pyrolysis-GC/MS, whereas the small PS bands in the ATR FT-IR spectrum were initially overlooked. The second was an item identified as polyethylene (PE) and PP by ATR FT-IR, but only PP was observed on the GC/MS chromatogram. Pyrolysis-GC/MS identified 90% of the unknowns and provided information on additives, both of which were not possible with ATR FT-IR alone. Six items (3 of which were analyzed by all labs and techniques) were examined using a 4-step process including ATR FT-IR, total transmission FT-IR, differential scanning calorimetry (DSC) and microscopic assessment of layers from thin sliced cross sections. Five of these items had multiple polymer layers, two of which were not revealed by ATR FT-IR alone.  DSC provides differentiation of PE densities (LDPE, LLDPE, and HDPE); whereas presence/absence of a band at 1377 cm^-1 in the ATR FT-IR spectra is not always reliable. Polymer identification of marine debris pieces is not necessarily straightforward and a multiple-method approach is required for complete and accurate identifications.

Names that will be included in acknowledgements on the poster:

David Springer and Taanya Ramirez – Chevron Phillips for lab assistance

Jens Currie (PWF) and Kevin O’Brien (NOAA) for one sample each that went to Ashok

ABS vs PS in Jung et al not differentiated at all based on abundance peaks shown, so you MUST use 2235 (present in all 3 MJ’s ABS consumer goods; absent in all PS consumer goods plus raw PS standards).

A Novel Analytical Method to Assess Microplastic Diversity, Abundance and Mass in the Marine Environment Samples

Luis E. Medina Faull, Tatiana Zaliznyak, and Gordon T. Taylor

NAno-RAMAN Molecular Imaging Laboratory, School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, 11794 USA

To date, research into marine microplastic (MP) pollution has focused on quantifying the total number of MP particles from environmental samples using techniques suitable for particles >300µm. Consequently, an important fraction of the particles have likely been understudied, leading possibly to an underestimation of the ocean’s plastic budget. Moreover, unlike total mass, particle number is not a conserved unit and doesn’t translate to total plastic for budget calculations. It is also not yet clear how oceanographic processes, sampling methods, or analytical techniques could affect the breakdown of these particles. These issues require the measurement of MP mass as a determinant of total plastic loads. Using Raman microspectroscopy coupled with 3-D spectral imaging, we have developed an automatable methodology to be applied to environmental samples for detection, identification, and quantification by mass of micron-sized MPs directly from filters. This method can detect MP particles less than 20µm in diameter and generating 3-dimensional images based on the Raman spectra of the polymer. The volume of an individual particle can be determined, and the mass calculated based on known MP densities. This methodology will enable the estimation of MP mass, providing vital information for mass balance calculations of MPs in the ocean.

Microplastic analysis in the coastal environment and in the eastern oyster (Crassostrea virginica)

Kayla M. Mladinich, J. Evan Ward, Sandra E. Shumway

Microplastics (MP, < 5 mm) are present across environmental compartments, including water, biota and marine snow (heteroaggregations). These particles can incorporate in marine snow thus sinking faster than individual particles and increasing the level of MP to which benthic organisms are exposed. Studies have demonstrated that benthic animals, including suspension feeders, consume MP and under certain experimental conditions consumption can lead to harmful effects. This research works to characterize MP found on a recreational oyster bed (eastern oyster, Crassostrea virginica) in Norwalk, Connecticut by identifying the polymer composition, shapes and sizes. Oysters, water, and marine snow samples were collected in the fall and spring for MP analysis. Oysters were chosen because they are an abundant suspension feeder, commercially important, and feed discriminately; they do not consume all particles to which they are exposed. Precautions were taken to minimize MP contamination in the laboratory and field such as: pre-filtering liquid reagents, ashing glassware prior to use, and wearing cotton laboratory coats at all times. All samples (oyster digestive gland and gut, water, marine snow) were processed using validated digestion methods, and polymer structures identified using Raman and Fourier Transform Infrared spectroscopic methods. These data will aid in determining the types of MP (polymer composition, shape, size) to which oysters are exposed, and help identify MP that they actually ingest. Such comparisons are important to determine if MP in the environment are problematic for the eastern oyster and if so, what MP types should be addressed in future environmental policies.

Rapid Identification of Plastics via Spectroscopic Techniques and Classification Methods

Alexandra E. Morrison¹, Victoria L. Preston^1,2, Charles T. Marx³, Beckett C. Colson^1,4,

Christine C. Anderson³, Helen K. White³, Anna P.M. Michel¹

¹Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA 02543

²Department of Aeronautical and Astronautical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139

³Department of Chemistry, Haverford College, Haverford, PA 19041

⁴Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139

Rapid technologies with in situ capabilities are necessary for plastic identification with applications ranging from recycling to the characterization of plastics found in the environment. In this study, four rapid (< 1 min), non-destructive, and field-ready spectroscopic techniques are compared: attenuated total reflectance - Fourier transform infrared spectroscopy (ATR-FTIR), near-infrared (NIR) reflectance spectroscopy, laser induced breakdown spectroscopy (LIBS), and x-ray fluorescence spectroscopy (XRF). In order to determine the effectiveness of these techniques for identifying plastic type, 30 consumer plastic samples from each recycling code (1-6) were analyzed via all four techniques. The success of each technique was then evaluated using five classification methods: hand-designed heuristic models, naive spectral matching, principal component analysis coupled to support vector machine (PCA-SVM), K-nearest neighbors (kNN), and linear discriminant analysis. Linear discriminant analysis achieved the highest classification rates coupled to ATR-FTIR, LIBS, and NIR reflectance spectroscopy when analyzing consumer plastics, with successful classification rates of 99%, 97%, and 90% respectively. The four spectroscopic techniques coupled to the highest performing models (linear discriminant analysis and kNN) were then evaluated using 100 samples of marine debris in order to establish the robustness of each method to environmental processes, as well as to examine the success rates of classifying environmental plastics.

Microplastics in Cape Cod salt marsh sediments: history and abundances

Rut Pedrosa-Pamies¹, Javier Lloret¹, Nicole Vandal², Claire McGuire³

(¹)Marine Biological Laboratory, (²)Amherst College, (³)Rhodes College

Microplastic (debris <5 mm) contamination of the oceans is one of the world’s most pressing environmental concerns. Our understanding of the distribution of plastic debris in the oceans has recently increased thanks to studies in ocean gyres, open seas, wave-exposed beaches and deltas, and deep sea. However, the salt marsh component of the global microplastic budget is not well understood. The relatively minor bioturbation and hydrological disturbances observed in salt marshes make salt marsh sediments a natural, relatively stable, time-sensitive repository of microplastics.

We report microplastic abundance, classified by type, in salt marsh sediment cores to determine the historical trend of microplastic accumulation during the last eight decades. Three ~24 cm-deep sediment cores were collected in salt marshes of two estuaries within the Waquoit Bay (Cape Cod, MA) estuarine system: Childs River, an estuary with a relatively urbanized watershed, and Timm’s Pond, with a forested watershed. Microplastic particles were found in all sampled sediments, but were 12 times more abundant in Childs River than in Timm’s Pond cores. The lowest abundances of microplastics were found in the deeper segments of the cores, dating back to the 1960s and earlier. Microplastic abundances increased 9-fold in the most recent core segments. The increase in global plastic production and usage in recent decades, and degree of urban development in Cape Cod, is reflected in the accumulation of microplastics, accumulation that goes beyond densely populated areas.

Microplastics in Coastal Marine Animals: Defining the Problem

Jordan Avery Pitt,¹ Neel Aluru,¹ and Mark E. Hahn,<sup>1

1</sup> Biology Department, Woods Hole Oceanographic Institution (WHOI)

The fate and toxicity of microplastics and nanoplastics in the natural environment are of great concern worldwide but are poorly understood. There is little known about these particles’ interactions with biota in the marine environment; however, microplastics have been found ubiquitously in animals at different trophic levels and at all depths sampled. Some studies have used fluorescently labeled nanoplastic beads to show that these particles are capable of passing through the gut epithelium as well as the blood-brain barrier; however, the concentrations used are often unrealistically high. To address this concern, and building on previous studies (Pitt et al. 2018a, Aquat Toxicol 194: 185-194; Pitt et al. 2018ab, Sci Total Environ 643: 324-334), we have initiated a two-part research project. First, using a range of particle sizes and zebrafish (Danio rerio) as a model organism, we are conducting a systematic investigation of the size-dependence of the ability of microplastics and nanoplastics to cross epithelial barriers including the gut epithelium and blood-brain barrier. Second, we will sample marine animals from around Cape Cod, including those used as seafood, in order to determine the concentrations of plastics found in the gastro-intestinal tract and other organs such as the brain, under natural environmental conditions. The quantitative understanding of the fraction of microplastics that pass through membrane barriers and concentrations of plastics in local animals will enable better predictions of the hazard posed by nanoplastics and microplastics in the marine environment. [Supported by the WHOI Academic Programs Office and a graduate fellowship from the U.S. National Science Foundation.]

Plastic: A potential carbon source for sedimentary biogeochemical cycling

Kelsey L. Rogers (klrogers@ign.ku.dk), Joan A. Carreres-Calabuig (jac@ign.ku.dk), Serguei Chiriaev (schi@mci.sdu.dk), Nicole R. Posth (nrep@ign.ku.dk)

Sediment is the ultimate sink for microplastics. Given the current trends in plastic production and waste treatment, plastic deposition to the sediment is expected to continue. Some plastics, such as polyethylene (PE) and polystyrene (PS) exhibit biodegradability, albeit at very slow rates and not determined in conditions found in sediment. Plastic degradation is aided by the presence of light and oxygen; however, after these plastics settle to sediment it remains unclear how dark, low oxygen conditions typical of sediment influence biofilm development, degradation or conservation of plastic. To explore the biogeochemistry of plastic under these conditions, wood, PE, and PS were placed in the water column and sediment of Svanemøllen Harbor, a Danish marina in central Copenhagen. Throughout a year of exposure, these substrates were periodically subsampled to analyze for biofilm development and potential plastic degradation. Concurrently, sediment cores were analyzed for sulfide, phosphate, dissolved inorganic carbon, methane, and ammonium to track redox zonation over time.  The plastic-associated biofilm was characterized using DNA sequencing, biofilm assay, and He-ion microscopy and compared to the ambient microbial community in the water column and sediment. He-ion microscopy was also used to visually inspect the surface of the plastic for evidence of degradation and to describe the microbial community. Several species of diatoms were present on the plastics and potentially rotifers, known diatom predators. Preliminary results show that, during the spring bloom, the sulfate reduction zone corresponded with the most biofilm development on PE in the sediment. After six months, the biofilm present on PE and PS increased, but the biofilm on PE was more stable and constant at all core depths.

Different microplastics can influence structure and function of sediment microbial communities

Meredith Seeley

Plastics are now ubiquitous in freshwater, coastal and open ocean environments. Sediments therein have been discovered to be a major sink for microplastics. While plastic polymer type has been suggested to influence the composition of floating plastic biofilm communities, studies to date have not investigated the effects of different microplastics on sediment microbial communities or sediment biochemical activities. Here, we present the results of a sediment microcosm experiment established with microplastics (53-300 um) of different petroleum-based polymers (polyethylene [PE], polyvinyl chloride [PVC] and polyurethane foam [PUF]) and one bio-polymer (polylactic acid [PLA]). We characterized the sediment bacterial compositions and functional gene abundances after 7 and 16 days incubation using 16S MiSeq and quantitative polymerase chain reaction (qPCR) analyses, respectively. Nitrogen cycling was also evaluated by measuring dissolved inorganic N fluxes and denitrification rates (calculated via sediment slurry incubation experiments using a 15N isotope pairing technique). We observed that bacterial community compositions differed significantly between the biopolymer, petroleum-based polymers and non-amended sediment, with PVC being the most distinctly unique community. Nitrification gene abundances and inorganic N fluxes revealed that nitrification was highest in the biopolymer (PLA) and PUF, and lowest in PVC treatments. Correspondingly, denitrification rates were inhibited in PVC, but highest in PLA and PUF. Both denitrification and nitrification activities were higher in PE, PUF and PLA treatments than the non-amended control. This suggests that: (1) microplastics can alter sedimentary nitrogen cycling processes and (2) sediment microbial communities may have the capacity to use plastics as carbon substrate. Overall, our study shows that the environmental presence of different microplastics may alter the structure and function of sediment microbial communities.

All that glitters is not plastic: the case of open-ocean textile fibres

 Giuseppe Suaria^1*, Aikaterini Achtypi¹, Vonica Perold², Stefano Aliani¹, Peter G Ryan²

¹ISMAR-CNR, Institute of Marine Sciences, National Research Council, 19032, La Spezia, Italy

²FitzPatrick Institute, University of Cape Town, Rondebosch, 7701, South Africa.

*corresponding author: giuseppe.suaria@sp.ismar.cnr.it

Textile fibres are ubiquitous contaminants of emerging concern. Traditionally ascribed to the ’microplastics’ family, their widespread occurrence in the natural environment is commonly reported in plastic pollution studies, with the misleading belief that they largely derive from wear and tear of synthetic fabrics. Their synthetic nature has been largely used to motivate their persistence in the environment, thus explaining their presence in virtually all compartments of the planet, including sea-ice, deep-seas, soils, atmospheric fall-out, foods and drinks. As of today however, an extensive characterization of their polymeric composition has never been performed, even though the evidence that most of these fibres are not synthetic, is slowly emerging. By compiling a dataset of more than 916 seawater samples collected in six different ocean basins, we confirm that microfibres are ubiquitous in the world seas, but mainly composed of natural polymers. The chemical characterization of almost 2000 fibres through µFTIR techniques revealed that only 8.2% of these fibres are actually synthetic, with the rest being predominantly of animal (12.3%) or vegetal origin (79.5%). These results demonstrate the widespread occurrence of cellulosic fibres in the marine environment, emphasizing the need for full chemical identification of these particles, before classifying them as microplastics. On the basis of our findings it appears critical to assess origins, impacts and degradation times of cellulosic fibers in the marine environment, as well as to assess the wider implications of a global overestimation of microplastic loads in natural ecosystems.

The impacts of microplastics on a largely overlooked keystone marine invertebrate - the sea urchin.

Coleen C. Suckling

Fisheries, Animal and Veterinary Sciences, University of Rhode Island, 134 Woodward Hall, 9 East Alumni Avenue, Kingston, RI 02881.USA.

In recent years there has been an increasing effort to assess the impacts of microplastic pollution on marine organisms, yet much focus has been made on filter feeding shellfish and fish species of commercial relevance. Other ecologically and economically important groups of organisms, such as sea urchins, have still received little to no investigation.  Here the first insights into assessing the effects of marine microplastics on numerous species of adult sea urchins (Arbacia punctulata, Paracentrotus lividus, Psammechinus miliaris) are presented thus bringing new information into the field of microplastic pollution.

Sea urchins live on the benthos grazing on food materials meaning that these organisms are at the interface for plastic exposure, through plastic loading and resuspension during events of significant water movement (e.g. storms). This study assessed the short term influence of storm-like scenarios which could induce microplastic resuspension from sediments coupled with salinity changes associated with high precipitation during storm events. Furthermore it assessed the longer term effects of ingesting PVC particles using environmentally relevant levels of each parameter.

This study shows that numerous species of sea urchins are resilient to microplastic pollution even when coupled with additional parameters. More importantly our study shows that the urchins ingest microplastics, a phenomenon not previously documented for adults.