Ingested Micronizing Plastic Particle Compositions and Size Distributions within Stranded Post-Hatchling Sea Turtles

A best practice framework for assessing plastic ingestion in marine turtles

The ingestion of plastic debris has been reported in all seven marine turtle species, affecting vital processes throughout their entire life cycle and key habitats. Consequently, this emerging threat has been recognized as a priority conservation concern. The potential health impacts range from cryptic sublethal effects to severe injury and death. A comprehensive understanding of these impacts and the processes involved, at both the individual and population levels, is crucial for evaluating the vulnerability of marine turtles to plastic pollution. Aiming to guide researchers and stakeholders from the initial stages of project development, this study discusses essential components for establishing and achieving research on plastic ingestion in marine turtles. Drawing on diverse efforts globally, this manuscript compiles the most common approaches and established methodologies, while evaluating resource availability and capabilities, to outline a globally applicable best practice framework for designing and implementing research and monitoring initiatives on plastic ingestion impacts to marine turtles.

Polystyrene microplastics exposure in freshwater fish, Labeo rohita: evaluation of physiology and histopathology

The goal of this investigation was to assess the adverse impacts of polystyrene microplastics (PS-MPs) on Labeo rohita with a comprehensive assessment of growth performance, hematological changes, and histopathological effects. Six test diets were established with different MPs levels using canola meal as the basal diet: control 0.0%, 0.5%, 1%, 1.5%, 2%, and 2.5% MPs. For 90 days, 315 fish (15 fish per tank with three replicates) were fed experimental diets at a rate of 5% of their live, twice a day. L. rohita fingerlings treated with 2.5% MPs leading to a notable decline in growth and feed consumption (P < 0.05). As PS-MPs increased, carcass, mineral and digestibility content declined. Additionally, a histology of the gut revealed significant abnormalities in intestine, including villi structure disruption and increased mucus cell proliferation, at a 2.5% PS-MPs concentration. Hematological indices such as RBCs, Hb, PLT, MCHC, and PCV decreased significantly when exposed to MPs, whereas WBCs, MCH, and MCV dramatically increased. Conclusively, this study demonstrated that the PS-MPs exert detrimental effects on growth performance, and induce histopathological and hematological changes in L. rohita.

Transformations of crude oil into tar: a case study from a plastitar-contaminated site in NE Sicily, Italy (Western Mediterranean)

This study examines the aging of industrial crude oil to simulate the chemical transformations that occur when it is exposed to environmental conditions over time. It was triggered by the finding of plastitar - a mixture of tar and plastic waste - on the coast of Milazzo, Sicily. Research began with a chemical characterization of the tar component of plastitar, followed by aging experiments designed to simulate environmental conditions such as seawater, UV light and sunlight. Fourier transform infrared spectroscopy (FTIR) was used to analyze the chemical changes during the aging process and compare the results with local tar samples. The results showed significant chemical changes in the aged crude oil, including oxidation, degradation of hydrocarbons and the formation of oxygenated compounds. In particular, the FTIR spectra of the aged crude oil closely matched those of the local tar and provided valuable insights that could help address similar coastal pollution issues in other regions.

Microplastic pollution in commercially important edible marine bivalves: A comprehensive review

Microplastics have become major pollutants in the marine environment and can accumulate in high concentrations, especially in the gut of marine organisms. Unlike other seafood, bivalves are consumed whole, along with their digestive systems, resulting in the transfer of microplastics to humans. Therefore, there is an urgent need to review the status of microplastic pollution in marine bivalves. In this context, this article provides a comprehensive review of the status of microplastic pollution in marine bivalves and the impact of microplastics on the physiology and immunology of marine bivalves. In general, marine bivalves can accumulate high levels of microplastics in a tissue-specific manner. Although microplastic pollution does not cause mortality in bivalves, it can adversely affects bivalves' immunity, byssus production, and reproduction, potentially affecting bivalve populations. This article provides important information that will aid establishing management measures and determining the direction of future research.

First register of microplastic contamination in oysters (Crassostrea gasar) farmed in Amazonian estuaries

The present study investigated the contamination of oysters farmed in Amazonian estuaries by microplastics (MPs). A total of 120 adult oysters (Crassostrea gasar) were collected from four sites along the Mangrove Coast of Pará/Brazil: S1, S2, S3 and S4, with 30 oyster for each. Overall, 58.33 % of the oyster samples contained microplastics, with mean concentrations of 0.23 MPs/g and 1.9 MPs/ind. The concentration of microplastics varied among the four sites, where S1 and S3 had the highest values while S4 had the lowest. PA fibers were the majority of particles (91 %), followed by PS fragments (9 %). The hepatopancreas and the gonad concentrated more microplastics than the rest of the body. As an important species for aquaculture in Amazon, we recommend additional regulation to reduce human exposure to microplastics, such as the installation of depuration facilities and constant monitoring of the contamination of oysters from farms in the region.

Development of a multi-spectroscopy method coupling μ-FTIR and μ-Raman analysis for one-stop detection of microplastics in environmental and biological samples

Current techniques for microplastics (MPs) analysis are diverse. However, most techniques have individual limitations like the detection limit of spatial resolution, susceptibility, high cost, and time-consuming detection. In this study, we proposed a multi-spectroscopy method coupling μ-FTIR and μ-Raman analysis for one-stop MPs detection, in which barium fluoride was used as the substrate alternative to the filter membrane. Compared with commonly used filter membranes (alumina, silver, PTFE and nylon membranes), the barium fluoride substrate showed better spectroscopic detection performance on microscopic observation, broader transmittable wavenumber range for μ-FTIR (750-4000 cm-1) and μ-Raman (250-4000 cm-1) detection, thus suitable for the multi-spectroscopy analysis of spiked samples. Further, the real environmental and biological samples (indoor air, bottled water and human exhaled breath) were collected and detected to verify the applicability of the developed multi-spectroscopy method. The results indicated that the average content of detected MPs could be increased by 30.4 ± 29.9 % for indoor air, 17.1 ± 13.2 % for bottled water and 38.4 ± 16.0 % for human exhaled breath, respectively in comparison with widely used μ-Raman detection, which suggested that MPs exposure might be underestimated using single spectroscopy detection. Moreover, the majority of underestimated MPs were colored and smaller sized (<50 μm) MPs, which could pose higher risks to human body. In addition, the proposed method consumed lower sample pre-treatment costs and was environmental-friendly since the barium fluoride substrate could be used repeatedly after being cleaned by organic solvent with reliable results (n = 10, CV = 10 %, ICC = 0.961), which reduced the cost of MPs detection by at least 2.49 times compared with traditional methods using silver membrane.

The pollution characteristics and risk assessment of microplastics in mollusks collected from the Bohai Sea

Microplastics (MPs) pollution in the marine environment has become a global problem. In this study, a number of 21 mollusk species (n = 2006) with different feeding habits were collected from 11 sites along the Bohai Sea for MPs uptake analysis. The MPs in mollusk samples were isolated and identified by micro-Fourier Transform Infrared Spectroscopy (μ-FTIR), and an assessment of the health risks of MPs ingested by mollusk consumption is also conducted. Approximately 91.9 % of the individuals among all the collected species inhaled MPs, and there was an average abundance of 3.30 ± 2.04 items·individual-1 or 1.04 ± 0.74 items·g-1 of wet weight. The shape of MPs was mainly fiber, and a total number of 8 polymers were detected, of which rayon had the highest detection rate (58.3 %). The highest abundance, uptake rate and polymer composition of MPs was observed in creeping types, suggesting that they might ingest these MPs from their food. The gastropod Siphonalia subdilatata contains the highest levels of MPs, which may increase the risk of human exposure if consumed whole without removing the digestive gland. The polymer risk level of MPs in these mollusks was Level III (H = 299), presenting harmful MPs such as polyvinyl chloride. In terms of human exposure risk, the average risk of human exposure to MPs through consumption of Bohai mollusks is estimated to be 3399 items·(capita·year)-1 (424-9349 items·(capita·year)-1). Overall, this study provides a basis for the ecological and health Risk assessment of MPs in mollusks collected from the coastline of China.

Biological effects on the migration and transformation of microplastics in the marine environment

Microplastics(MPs) are ubiquitous, difficult to degrade, and potentially threatening to organisms in marine environment, so it is important to clarify the factors that affect their biogeochemical processes. The impact of biological activities on the MPs in marine environment is ubiquitous and complex, and there is currently a lack of systematic summaries. This paper reviews the effects of biological actions on the migration, distribution and degradation of MPs in marine environment from four aspects: biological ingestion and digestion, biological movement, biological colonization and biological adhesion. MPs in seawater and sediments can be closely combined with organisms through three pathways: biological ingestion, biofilm formation or adhesion to organisms, and are passed between species at different trophic levels through the food chain. The generation and degradation of faecal pellets and biofilms can alter the density of "environmental MPs", thereby affecting their vertical migration and deposition in water bodies. The movement of swimming organisms and the disturbance by benthic organisms can promote the migration of MPs in water and vertical migration and resuspension in sediments, thereby changing the distribution of MPs in local sea areas. The grinding effect of the digestive tract and the secretion of chemicals from the biofilm (such as enzymes and acids) can reduce the particle size and increase surface roughness of MPs, or even degrade them completely. Besides, biological adhesion may be an important mechanism affecting the distribution, migration and preservation of MPs. There may be complex interactions and linkages among marine dynamical processes, photochemical degradation and biological processes that collectively affect the biogeochemical processes of MPs, but their relative contributions remain to be more studied.

Construction of Fusion Protein with Carbohydrate-Binding Module and Leaf-Branch Compost Cutinase to Enhance the Degradation Efficiency of Polyethylene Terephthalate

Poly(ethylene terephthalate) (PET) is a manufactured plastic broadly available, whereas improper disposal of PET waste has become a serious burden on the environment. Leaf-branch compost cutinase (LCC) is one of the most powerful and promising PET hydrolases, and its mutant LCCICCG shows high catalytic activity and excellent thermal stability. However, low binding affinity with PET has been found to dramatically limit its further industrial application. Herein, TrCBM and CfCBM were rationally selected from the CAZy database to construct fusion proteins with LCCICCG, and mechanistic studies revealed that these two domains could bind with PET favorably via polar amino acids. The optimal temperatures of LCCICCG-TrCBM and CfCBM-LCCICCG were measured to be 70 and 80 °C, respectively. Moreover, these two fusion proteins exhibited favorable thermal stability, maintaining 53.1% and 48.8% of initial activity after the incubation at 90 °C for 300 min. Compared with LCCICCG, the binding affinity of LCCICCG-TrCBM and CfCBM-LCCICCG for PET has been improved by 1.4- and 1.3-fold, respectively, and meanwhile their degradation efficiency on PET films was enhanced by 3.7% and 24.2%. Overall, this study demonstrated that the strategy of constructing fusion proteins is practical and prospective to facilitate the enzymatic PET degradation ability.

Identification of Trace Polystyrene Nanoplastics Down to 50 nm by the Hyphenated Method of Filtration and Surface-Enhanced Raman Spectroscopy Based on Silver Nanowire Membranes

Nanoplastics are emerging pollutants that pose potential threats to the environment and organisms. However, in-depth research on nanoplastics has been hindered by the absence of feasible and reliable analytical methods, particularly for trace nanoplastics. Herein, we propose a hyphenated method involving membrane filtration and surface-enhanced Raman spectroscopy (SERS) to analyze trace nanoplastics in water. In this method, a bifunctional Ag nanowire membrane was employed to enrich nanoplastics and enhance their Raman spectra in situ, which omitted sample transfer and avoided losing smaller nanoplastics. Good retention rates (86.7% for 50 nm and approximately 95.0% for 100-1000 nm) and high sensitivity (down to 10^-7 g/L for 50-1000 nm and up to 10⁵ SERS enhancement factor) of standard polystyrene (PS) nanoplastics were achieved using the proposed method. PS nanoplastics with concentrations from 10^-1 to 10^-7 g/L and sizes ranging from 50 to 1000 nm were successfully detected by Raman mapping. Moreover, PS micro- and nanoplastics in environmental water samples collected from the seafood market were also detected at the μg/L level. Consequently, the proposed method provides more possibilities for analyzing low-concentration nanoplastics in aquatic environments with high enrichment efficiency, minimal sample loss, and high sensitivity.

Junk food: Polymer composition of macroplastic marine debris ingested by green and loggerhead sea turtles from the Gulf of Oman

Pollution of the marine environment by plastic marine debris has become one of the most pervasive threats impacting marine environments. In this study, for the first time, we evaluate the polymer types of the plastic marine debris ingested by 49 green and 14 loggerhead sea turtle strandings in the Gulf of Oman. Plastic marine debris was ingested by 73.5% of green and 42.9% of loggerhead sea turtles in this study. Overall, evidence suggested that green sea turtles from the Gulf of Oman coast of the United Arab Emirates ingested high levels of plastic marine debris, predominantly Polypropylene (PP) & Polyethylene (PE), followed by Nylon, PP-PE mixture, Polystyrene (PS), Poly vinyl chloride (PVC) and Ethylene vinyl acetate (EVA), respectively. Loggerhead sea turtles also ingested high levels of plastic marine debris, which also predominantly consisted of PP & PE, followed by PP-PE mixture, Nylon and PS. While recent studies were directed into polymer characterization of micro-plastics in aquatic life, our study focuses on macro-plastics which impose significantly greater risks.

Ingestion and characterization of plastic debris by loggerhead sea turtle, Caretta caretta, in the Balearic Islands

Plastic waste has become ubiquitous pollutants in seas and oceans and can affect a wide range of species. For some marine species, plastic debris could pose a considerable threat through entanglement, ingestion, and habitat degradation and loss. Sea turtles are one of the most sensitive species, as their migratory behaviour and multifaceted life cycles make these reptiles especially vulnerable to the negative effects of plastic debris. The present study aimed to assess the amount and composition of plastic debris ingested by loggerhead turtles (Caretta caretta, Linnaeus, 1758) in the Balearic Islands Sea, thusly providing new information to complete the knowledge for this topic. In this work, 45 stranded dead C. caretta specimens were necropsied, and their digestive tract content analysed for the presence of plastic debris. Plastic objects were observed in 27 individuals (60.0%), with an average of 12.7 ± 4.7 plastic items per turtle. Litter in the faecal pellet was also monitored in 67 living individuals, observing plastic elements in 46 (68.7%) of the specimens, reporting an average of 9.7 ± 3.3 plastic elements per individual. Overall, 785 plastic items were found, measured, weighed and categorized according to size, colour, shape, and type of polymer. The main elements ingested were plastic sheets that were found in 65.3% of the turtles analysed, being white (42.7%) and transparent (29.2%) the most predominant colours. Most elements were macroplastics (59.3%), while microplastics were not found. Fourier Transform Infrared Spectrometry (FT-IR) analysis showed that high-density polyethylene and polypropylene were the main polymer plastics, representing 42.3% and 33.8% of the total, respectively. In conclusion, the high occurrence of plastic debris determined in the present study evidenced for the first time plastic ingestion in loggerhead turtles in the Balearic Islands, and highlights C. caretta as a bioindicator organism for marine pollution.

Impacts of conventional and biodegradable microplastics on juvenile Lates calcarifer: Bioaccumulation, antioxidant response, microbiome, and proteome alteration

Discarded plastic bag is a main component of marine debris, posing potential threats to marine biota. This study was conducted to assess the potential effects of microplastics on juvenile Lates calcarifer. Fish were exposed via diet to two microplastic types from conventional polyethylene (PE) and biodegradable (Bio) plastic bags for 21 days. Antioxidative enzymes activity, intestinal microbiome and proteome were determined. PE and Bio microplastics were found to accumulate in gastrointestinal tracts, and no mortality was observed. Microplastics exposure did not induce significant antioxidant response except for the glutathione reductase (GR) modulation. Intestinal microbiome diversity decreased significantly in PE group based on Simpson index. Both types of microplastics induced proteome modulation by down-regulating proteins associated with immune homeostasis. Bio microplastics maintained higher intestinal microbial diversity and induced more proteins alteration than PE microplastics. This study provides toxicological insights into the impacts of conventional and biodegradable microplastics on juvenile L. calcarifer.

Litter ingestion and entanglement in green turtles: An analysis of two decades of stranding events in the NE Atlantic

Survivorship of early life stages is key for the well-being of sea turtle populations, yet studies on animals that distribute around oceanic areas are very challenging. So far, the information on green turtles (Chelonia mydas) that use the open NE Atlantic as feeding grounds is scarce. Strandings occurring in oceanic archipelagos can provide relevant information about the biology, ecology and current anthropogenic pressures for megafauna inhabiting the open ocean. In this study, we analysed stranding events of green turtles found in the Azores archipelago to investigate interactions with marine litter. In addition, we quantified and characterized litter items stranded on beaches to provide a direct comparison between the ingested items with the debris found in the environment. A total of 21 juvenile green turtles were found stranded in the region between 2000 and 2020 (size range: 12-49 cm, CCL). Overall, 14% of the animals were entangled in marine litter and 86% of the turtles necropsied had ingested plastic. The mean abundance of items ingested was 27.86 ± 23.40 and 98% were white/transparent. Hard plastic fragments between 1 and 25 mm were the most common shape recovered in the turtles, similarly to what was found on the coastline. All of the litter items analysed with pyrolysis GC-MS revealed to be polyethylene (PE). This study provides the first baseline assessment of interactions of plastic litter with juvenile green turtles found at the east edge of the North Atlantic Subtropical Gyre. The combination of these results supports the hypothesis that migratory megafauna that use remote oceanic islands as a feeding ground are exposed to anthropogenic litter contamination dominated by plastics, even when these regions are located far away from big industrial centers or populated cities.

Fluorescent Polypropylene Nanoplastics for Studying Uptake, Biodistribution, and Excretion in Zebrafish Embryos

Nanoplastics (NPs) are emerging environmental pollutants and are a significant concern for human health. The small size of NPs allows them to accumulate within and adversely affect various tissues by penetrating the gastrointestinal barrier. However, most toxicity studies on NPs have been based on commercial polystyrene nanoparticles. Among plastics, polypropylene (PP) is one of the most widely used, and it is continuously micronized in the environment. Although PP has high potential for forming NPs by weathering, little is known about the biological effects of polypropylene nanoplastics (PPNPs) due to a lack of particle models. Here, we present a simple and high-yield method for PPNP production by nonsolvent-induced phase separation. The synthesized PPNPs were spherical in shape, with an average diameter of 562.15 ± 118.47 nm and a high yield of over 84%. These PPNPs were fluorescently labeled by the combined swelling-diffusion method to study their biodistribution after exposure to developing zebrafish embryos (ZFEs). We found that the fluorescent PPNPs were internalized by ingestion, distributed in the intestine of developing ZFEs, and eventually excreted. This study will aid evaluations of the potential risks of environmentally relevant plastics at the nanoscale.

Raman Spectroscopy for the Analysis of Microplastics in Aquatic Systems

Raman spectroscopy is gaining ground in the analysis of microplastics, especially due to its high spatial resolution that allows the investigation of small plastic particles, whose numeric abundance is argued to be particularly relevant in aquatic systems. Here, we aimed at outlining the status of Raman analysis of microplastics from aquatic systems, highlighting the advantages and the drawbacks of this technique and critically presenting tools and ways to effectively employ this instrument and to improve the spectra obtained and their interpretation. In particular, we summarized procedural information for the use of Raman spectroscopy, and we discussed issues linked to fluorescence interference and the analysis of weathered polymers, which may complicate the interpretation of Raman signatures. In this context, a deep understanding of the different plastic polymers and their Raman peaks and chemical fingerprints is fundamental to avoid misidentification. Therefore, we provided a catalog with detailed information about peaks of most common plastic polymers, and this represents, to the best of our knowledge, the first comprehensive resource that systematically synthesized plastic Raman peaks. Additionally, we focused on plastic additives, which are contained in the majority of plastics. These compounds are often intense in Raman scattering and may partly or completely overlie the actual material types, resulting in the identification of additives alone or misidentification issue. For these reasons, we also presented a new R package "RamanMP" that includes a database of 356 spectra (325 of which are additives). This will help to foster the use of this technique, which is becoming especially relevant in microplastic analysis.

Incidence of microplastics in gastrointestinal tract of golden anchovy (Coilia dussumieri) from north east coast of Arabian Sea: The ecological perspective

Anthropogenic marine litters or microplastics (MPs) accumulation in marine organisms is an emerging environmental threat. In this background, the gastrointestinal tract of Coilia dussumieri (n = 150) was studied in the samples collected from the fishing grounds of the north east coast of Arabian Sea through experimental fishing. Out of the total 150 specimens collected, all showed the incidence of microplastic particulates in the guts. The average abundance of MPs was found to be 6.98 ± 2.73 items/individual whereas gastrointestinal tract recorded with an average number of 28.84 ± 10.13 MPs/g in the gut material. The dominant MPs were found in the size range of 100-250 μm and of fibers type mostly blue in color. The prevalence of MPs in Coilia dussumieri is a matter of serious concern due to its ecological consequences due to trophic transfer in the connected food chains and probable threats to the health of human beings consuming the fish.

Plastics in our water: Fish microbiomes at risk?

Water contaminated with plastic debris and leached plasticizers can be ingested or taken up by aquatic invertebrates and vertebrates alike, exerting adverse effects on multiple tissues including the gastrointestinal tract. As such, gut microbiomes of aquatic animals are susceptible targets for toxicity. Recent studies conducted in teleost fishes report that microplastics and plasticizers (e.g., phthalates, bisphenol A) induce gastrointestinal dysbiosis and alter microbial diversity in the gastrointestinal system. Here we synthesize the current state of the science regarding plastics, plasticizers, and their effects on microbiomes of fish. Literature suggests that microplastics and plasticizers increase the abundance of opportunistic pathogenic microorganisms (e.g. Actinobacillus, Mycoplasma and Stenotrophomonas) in fish and reveal that gamma-proteobacteria are sensitive to microplastics. Recommendations moving forward for the research field include (1) environmentally relevant exposures to improve understanding of the long-term impacts of microplastic and plasticizer contamination on the fish gastrointestinal microbiome; (2) investigation into the potential impacts of understudied polymers such as polypropylene, polyamide and polyester, and (3) studies with elastomers such as rubbers that are components of tire materials, as these chemicals often dominate plastic debris. Focus on both microplastics and the gut microbiota is intensifying in environmental toxicology, and herein lies an opportunity to improve evaluation of global ecological impacts associated with plastic contamination. This is important as the microbiota is intimately tied to an individual's health and fragmentation of microbial community networks and gut dysbiosis can result in disease susceptibility and early mortality events.

Microbiome Composition and Function in Aquatic Vertebrates: Small Organisms Making Big Impacts on Aquatic Animal Health

Aquatic ecosystems are under increasing stress from global anthropogenic and natural changes, including climate change, eutrophication, ocean acidification, and pollution. In this critical review, we synthesize research on the microbiota of aquatic vertebrates and discuss the impact of emerging stressors on aquatic microbial communities using two case studies, that of toxic cyanobacteria and microplastics. Most studies to date are focused on host-associated microbiomes of individual organisms, however, few studies take an integrative approach to examine aquatic vertebrate microbiomes by considering both host-associated and free-living microbiota within an ecosystem. We highlight what is known about microbiota in aquatic ecosystems, with a focus on the interface between water, fish, and marine mammals. Though microbiomes in water vary with geography, temperature, depth, and other factors, core microbial functions such as primary production, nitrogen cycling, and nutrient metabolism are often conserved across aquatic environments. We outline knowledge on the composition and function of tissue-specific microbiomes in fish and marine mammals and discuss the environmental factors influencing their structure. The microbiota of aquatic mammals and fish are highly unique to species and a delicate balance between respiratory, skin, and gastrointestinal microbiota exists within the host. In aquatic vertebrates, water conditions and ecological niche are driving factors behind microbial composition and function. We also generate a comprehensive catalog of marine mammal and fish microbial genera, revealing commonalities in composition and function among aquatic species, and discuss the potential use of microbiomes as indicators of health and ecological status of aquatic ecosystems. We also discuss the importance of a focus on the functional relevance of microbial communities in relation to organism physiology and their ability to overcome stressors related to global change. Understanding the dynamic relationship between aquatic microbiota and the animals they colonize is critical for monitoring water quality and population health.

Bioretention cells remove microplastics from urban stormwater

Microplastic pathways in the environment must be better understood to help select appropriate mitigation strategies. In this 2-year long field study, microplastics were characterized and quantified in urban stormwater runoff and through a bioretention cell, a type of low impact development infrastructure. Concentrations of microparticles ranged from below the detection limit to 704 microparticles/L and the dominant morphology found were fibers. High rainfall intensity and longer antecedent dry days resulted in larger microparticle concentrations. In addition, atmospheric deposition was a source of microplastics to urban runoff. Overall, these results demonstrate that urban stormwater runoff is a concentrated source of microplastics whose concentrations depend on specific climate variables. The bioretention cell showed an 84% decrease in median microparticle concentration in the 106-5,000 µm range, and thus is effective in filtering out microplastics and preventing their spread to downstream environments. Altogether, these results highlight the large contribution of urban stormwater runoff to microplastic contamination in larger aquatic systems and demonstrate the potential for current infiltration-based low impact development practices to limit the spread of microplastic contamination downstream.

Microplastic uptake in commercial fishes from the Bohai Sea, China

Microplastic (MP) pollution has become an emerging global concern in marine environments, but research on the uptake of MPs by commercial marine fish is relatively sparse. In this study, 29 commercial fish species (n = 584) with different feeding habits and trophic levels were collected from 8 sites along the Bohai Sea for MP uptake analysis. Approximately 85.4% of the total fish among all species ingested MPs, and there was an average abundance of 2.14 items/individual or 0.043 items/g of wet weight. Compared with other studies, MP pollution in fishes from the Bohai Sea was relatively moderate. The MPs were predominantly fibrous in shape and were cellophane, polyethylene terephthalate (PET) and polypropylene (PP) in polymer composition. The highest abundance and polymer composition of MPs was observed in benthivores, suggesting that they might ingest these MPs from their food. The small fish Konosirus punctatus, which had a high level of MPs, may increase the risk of human exposure to the MPs when it is dried and consumed. Moreover, the spatial variation of MPs was determined in terms of abundance, shape composition, and major polymer types, but there was no marked relationship between MP abundance and the trophic levels of fish. Overall, this study provides a basis for the ecological risk assessment of MPs in fish and for a health risk assessment for human beings.

Disease risk analysis in sea turtles: A baseline study to inform conservation efforts

The impact of a range of different threats has resulted in the listing of six out of seven sea turtle species on the IUCN Red List of endangered species. Disease risk analysis (DRA) tools are designed to provide objective, repeatable and documented assessment of the disease risks for a population and measures to reduce these risks through management options. To the best of our knowledge, DRAs have not previously been published for sea turtles, although disease is reported to contribute to sea turtle population decline. Here, a comprehensive list of health hazards is provided for all seven species of sea turtles. The possible risk these hazards pose to the health of sea turtles were assessed and "One Health" aspects of interacting with sea turtles were also investigated. The risk assessment was undertaken in collaboration with more than 30 experts in the field including veterinarians, microbiologists, social scientists, epidemiologists and stakeholders, in the form of two international workshops and one local workshop. The general finding of the DRA was the distinct lack of knowledge regarding a link between the presence of pathogens and diseases manifestation in sea turtles. A higher rate of disease in immunocompromised individuals was repeatedly reported and a possible link between immunosuppression and environmental contaminants as a result of anthropogenic influences was suggested. Society based conservation initiatives and as a result the cultural and social aspect of interacting with sea turtles appeared to need more attention and research. A risk management workshop was carried out to acquire the insights of local policy makers about management options for the risks relevant to Queensland and the options were evaluated considering their feasibility and effectiveness. The sea turtle DRA presented here, is a structured guide for future risk assessments to be used in specific scenarios such as translocation and head-starting programs.

Microplastics in fish meal: Contamination level analyzed by polymer type, including polyester (PET), polyolefins, and polystyrene

Fish meal (FM) is an industrial product, mainly obtained from whole wild-caught fish, that is used as a high protein feedstuff component in aquaculture and intensive animal farming. Contamination of FM by microplastics (MPs), the synthetic polymer particles known to be nearly ubiquitous in the marine environment, is a likely consequence of their ingestion by zooplankton and other small marine animals that through the food chain end up in the fish commercialized not only for direct human consumption but also for the industrial production of FM. Unfortunately, analytical tools for quantifying contamination of FM by synthetic polymers are not available. A newly developed procedure described here allows quantification of the total amounts of polyolefins (including ethene and propene homo- and copolymers), polystyrene (PS), and poly(ethylene terephthalate) (PET), respectively, in FM. The multi-step procedure involves a sequence of solvent extractions, hydrolytic treatments to remove the biogenic matrix mainly consisting of proteins and some lipids, and selective depolymerization for PET. The gravimetric and SEC-UV techniques employed for the quantification of polyolefins and PS, respectively, only allowed to estimate their concentration in FM at around or below 100 mg/kg each, a more accurate quantification being prevented by the interference from the organic matrix and, in the case of polyolefins, by the limited sensitivity of the quantification by gravimetry. On the other hand, the contamination by PET MPs could accurately be quantified at 12.9 mg/kg based on the dry FM mass. Ways to overcome the sensitivity limitations for PS and polyolefins by using e.g. pyrolysis-GC/MS are highlighted.

Investigating the presence of microplastics in demersal sharks of the North-East Atlantic

Microplastic pollution is ubiquitous in the marine environment and is ingested by numerous marine species. Sharks are an understudied group regarding their susceptibility to microplastic ingestion. Here, we provide evidence of ingestion of microplastic and other anthropogenic fibres in four demersal sharks species found in the waters of the United Kingdom and investigate whether body burdens of contamination vary according to species, sex or size. Sharks were collected from the North-East Atlantic. Stomachs and digestive tracts of 46 sharks of 4 species were examined and 67% of samples contained at least one contaminant particle. Although we acknowledge modest sample size, estimated particle burden increased with body size but did not vary systematically with sex or species. A total of 379 particles were identified, leading to median estimates ranging from 2 to 7.5 ingested contaminants per animal for the 4 species. The majority were fibrous in nature (95%) and blue (88%) or black (9%) in colour. A subsample of contaminants (N = 62) were subject to FT-IR spectroscopy and polymers identified as: synthetic cellulose (33.3%), polypropylene (25%), polyacrylamides (10%) and polyester (8.3%). The level of risk posed to shark species by this level of contamination is unknown. Nevertheless, this study presents the first empirical evidence and an important baseline for ingestion of microplastics and other anthropogenic fibres in native UK shark species and highlights the pervasive nature of these pollutants.

Occurrence of microplastics in epipelagic and mesopelagic fishes from Tuticorin, Southeast coast of India

This study investigated the microplastic (MP) contamination of seawater and fishes from different habitats so as to understand the level of human exposure to microplastics. Samples of Harpodon nehereus, Chirocentrus dorab, Sardinella albella, Rastrelliger kanagurta, Katsuwonus pelamis and Istiophorus platypterus were collected from Tuticorin, southeast coast of India. The MPs in seawater and the gastrointestinal tracts of fish were identified using Stereomicroscope and characterized by FTIR and SEM-EDAX analysis. The abundance of MPs varied from 3.1 ± 2.3 to 23.7 ± 4.2 items L^-1 in water, from 0.11 ± 0.06 to 3.64 ± 1.7 items/individual, and from 0.0002 ± 0.0001 to 0.2 ± 0.03 items/g gut weight. The epipelagic fishes had higher levels of MP contamination than the mesopelagic ones. Most of the MPs identified were of blue color, of fiber type and with their size <500 μm. Polyethylene was the most commonly detected MP, followed by polyester and polyamide, and this fact could be attributed to the inflow of domestic sewage and to the intensive fisheries activities in the area. SEM-EDAX spectra revealed the weathered MP surfaces which could adsorb/leach inorganic elements (colorants and fillers) from/to the environment. We may conclude that the concentration of MPs in fishes is a function of the concentration of MPs in their environment.

Microplastic serves as a potential vector for Cr in an in-vitro human digestive model

Microplastics (MPs), polymer particles capable of adsorbing heavy metals from ambient environment, have been found in diverse human food resources. Through the consumption of MPs, heavy metals adsorbed on MPs might be transported into human body. This study aims to explore the behavior of heavy metal-contaminated MPs in human digestive system which is not previously researched. Firstly, a chromium (Cr) adsorption/desorption study was conducted with four commonly used nondegradable MPs [polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and polystyrene (PS)] as well as one degradable MP (polylactic, PLA). Then, the whole digestive system in-vitro method (WDSM), a systematic model including mouth, gastric, small intestine, and large intestine digestive phases, was conducted on the Cr-loaded MPs. Additionally, the bioaccessibilities and hazard quotients (HQs) of Cr(VI) and Cr(III) were evaluated. Among five MPs, although PLA showed the weakest adsorption capacity for Cr, the Cr(VI) bioaccessibilities for PLA reached the highest values of 19.9%, 15.6% and 3.9% in gastric, small intestinal and large intestinal phases, respectively. The bioaccessibilities of Cr(VI) in gastric phase were significantly higher than those in other phases, while no Cr release from MPs was detected in the mouth phase. In gastric phase, the bioaccessibilities of Cr(VI) were significantly higher than those of Cr(III) in the gastric phase, and both of them approached to a similar level in intestinal phases. In the WDSM, the HQs of Cr(VI) and Cr(III) on MPs were lower than the critical level for both adults and children. Based on the measured bioaccessibilities, the maximum daily total Cr intake for different human groups (female children, male children, female adults and male adults) through MP consumption was estimated from 0.50 to 1.18 μg/day. In general, the five tested MPs were potential to serve as Cr vectors in the WDSM.

Ranking environmental degradation trends of plastic marine debris based on physical properties and molecular structure

As plastic marine debris continues to accumulate in the oceans, many important questions surround this global dilemma. In particular, how many descriptors would be necessary to model the degradation behavior of ocean plastics or understand if degradation is possible? Here, we report a data-driven approach to elucidate degradation trends of plastic debris by linking abiotic and biotic degradation behavior in seawater with physical properties and molecular structures. The results reveal a hierarchy of predictors to quantify surface erosion as well as combinations of features, like glass transition temperature and hydrophobicity, to classify ocean plastics into fast, medium, and slow degradation categories. Furthermore, to account for weathering and environmental factors, two equations model the influence of seawater temperature and mechanical forces.

Accumulation of micro and nano-plastic in the oceans has emerged as a global challenge. Here, the authors predict a hierarchy of features that regulate their degradation and surface erosion by a thorough analysis of polymer structure, composition, physical properties and degradation data.

Occurrence and Species-Specific Distribution of Plastic Debris in Wild Freshwater Fish from the Pearl River Catchment, China

Freshwater systems are an important source and vector of plastic debris found in oceans. However, plastic debris in freshwater organisms has not been well studied. The occurrence, characterization, polymer composition, and seasonal and spatial distribution of plastic debris were investigated in 9 species of wild freshwater fish from the Pearl River catchment, south China. Approximately 50% of the total fish (n = 279) belonging to 9 species were found to ingest plastic debris with an average abundance of 7.0 ± 23.8 items/individual, indicating wide plastic contamination in the Pearl River catchment. Plastic debris were predominantly transparent or white in color, fibers or fragments in shape, and polyethylene, polypropylene, ethylene-propylene copolymer (PE-PP), and polyethylene terephthalate (PET) in polymer composition. A species-specific distribution of the plastic debris was observed in terms of abundance, shape, and polymer composition. Redbelly tilapia had the highest (27.4 ± 54.0 items/individual), whereas common carp had the lowest (0.2 ± 0.4 items/individual) abundance of the plastic debris in their gastrointestinal tracts. Fibers of PET were predominant in the freshwater species except in barbel chubs, which had mostly PE-PP fragments. Omnivores and bottom-dwellers were more likely to ingest plastic debris. Seasonal variation was observed, with generally higher abundance of plastic debris in fish collected in the dry season than in the wet season. Environ Toxicol Chem 2019;38:1504-1513. © 2019 SETAC.

Microplastic ingestion ubiquitous in marine turtles

Despite concerns regarding the environmental impacts of microplastics, knowledge of the incidence and levels of synthetic particles in large marine vertebrates is lacking. Here, we utilize an optimized enzymatic digestion methodology, previously developed for zooplankton, to explore whether synthetic particles could be isolated from marine turtle ingesta. We report the presence of synthetic particles in every turtle subjected to investigation (n = 102) which included individuals from all seven species of marine turtle, sampled from three ocean basins (Atlantic [ATL]: n = 30, four species; Mediterranean (MED): n = 56, two species; Pacific (PAC): n = 16, five species). Most particles (n = 811) were fibres (ATL: 77.1% MED: 85.3% PAC: 64.8%) with blue and black being the dominant colours. In lesser quantities were fragments (ATL: 22.9%: MED: 14.7% PAC: 20.2%) and microbeads (4.8%; PAC only; to our knowledge the first isolation of microbeads from marine megavertebrates). Fourier transform infrared spectroscopy (FT-IR) of a subsample of particles (n = 169) showed a range of synthetic materials such as elastomers (MED: 61.2%; PAC: 3.4%), thermoplastics (ATL: 36.8%: MED: 20.7% PAC: 27.7%) and synthetic regenerated cellulosic fibres (SRCF; ATL: 63.2%: MED: 5.8% PAC: 68.9%). Synthetic particles being isolated from species occupying different trophic levels suggest the possibility of multiple ingestion pathways. These include exposure from polluted seawater and sediments and/or additional trophic transfer from contaminated prey/forage items. We assess the likelihood that microplastic ingestion presents a significant conservation problem at current levels compared to other anthropogenic threats.

Two decades of monitoring in marine debris ingestion in loggerhead sea turtle, Caretta caretta, from the western Mediterranean

Anthropogenic marine debris is one of the major worldwide threats to marine ecosystems. The EU Marine Strategy Framework Directive (MSFD) has established a protocol for data collection on marine debris from the gut contents of the loggerhead sea turtle (Caretta caretta), and for determining assessment values of plastics for Good Environmental Status (GES). GES values are calculated as percent turtles having more than average plastic weight per turtle. In the present study, we quantify marine debris ingestion in 155 loggerhead sea turtles collected in the period 1995-2016 in waters of western Mediterranean (North-east Spain). The study aims (1) to update and standardize debris ingestion data available from this area, (2) to analyse this issue over two decades using Zero-altered (hurdle) models and (3) to provide new data to compare the only GES value available (off Italian waters). The composition of marine debris (occurrence and amounts of different categories) was similar to that found in other studies for the western Mediterranean and their amounts seem not to be an important threat to turtle survival in the region. Model results suggest that, in the study area, (a) period of stranding or capture, (b) turtle size and (c) latitude are significant predictors of anthropogenic debris ingestion (occurrence and amount) in turtles. The GES value for late juvenile turtles (CCL>40 cm) has decreased in the last ten years in the study area, and this is very similar to that obtained in Italian waters. We also provide a GES value for early juvenile turtles (CCL≤40 cm) for the first time. Recommendations arising from this study include ensuring use of (1) the standardized protocol proposed by the MSFD for assessing marine debris ingestion by loggerhead sea turtles and (2) the ecology of the turtles (neritic vs oceanic), rather than their size, to obtain GES values.

Quantities of Marine Debris Ingested by Sea Turtles: Global Meta-Analysis Highlights Need for Standardized Data Reporting Methods and Reveals Relative Risk

Because of their propensity to ingest debris, sea turtles are excellent bioindicators of the global marine debris problem. This review covers five decades of research on debris ingestion in sea turtles from 131 studies with a novel focus on quantities. Previous reviews have focused solely on presence/absence data. Past reviews have called for standardization and highlight biases in the literature, yet none thoroughly describe improvements needed at the data reporting stage. Consequences of three reporting choices are discussed: not reporting quantities of ingested debris (32% of sea turtle studies reported only frequency of occurrence), excluding animals that did not ingest debris (64%), and not normalizing quantities to animal size (95%). Ingestion quantities, corrected for these factors, allowed a first-ever global meta-analysis on the units of grams/kilogram, revealing that hawksbill and green turtles rank highest among sea turtle species, and that the Central and Northwest Pacific and Southwest Atlantic Oceans are hotspots. Furthermore, this review discovered that monitoring efforts are disproportionate to the magnitude of the problem. Large efforts are focused in the Mediterranean Sea where international policies are hotly discussed versus the Central Pacific that has 5-fold greater debris ingestion quantities but represents only 3% of the global research effort. Future studies are recommended to report quantities of ingested debris using units described herein and make use of the pilot database provided.

Polymer Identification of Plastic Debris Ingested by Pelagic-Phase Sea Turtles in the Central Pacific

Pelagic Pacific sea turtles eat relatively large quantities of plastic (median 5 g in gut). Using Fourier transform infrared spectroscopy, we identified the polymers ingested by 37 olive ridley, 9 green, and 4 loggerhead turtles caught as bycatch in Hawaii- and American Samoa-based longline fisheries. Unidentifiable samples were analyzed using high-temperature size exclusion chromatography with multiple detectors and/or X-ray photoelectron spectroscopy. Regardless of species differences in dive depths and foraging strategies, ingested plastics were primarily low-density, floating polymers (51% low-density polyethylene (LDPE), 26% polypropylene (PP), 10% unknown polyethylene (PE), and 5% high-density PE collectively). Albeit not statistically significant, deeper diving and deeper captured olive ridley turtles ate proportionally more plastics expected to sink (3.9%) than intermediate-diving green (1.2%) and shallow-diving loggerhead (0.3%) turtles. Spatial, but no sex, size, year, or hook depth differences were observed in polymer composition. LDPE and PP, some of the most produced and least recycled polymers worldwide, account for the largest percentage of plastic eaten by sea turtles in this region. These novel data inform managers about the threat of plastic ingestion to sea turtles and may motivate development of more environmentally friendly practices for plastic production, use, and waste management.