Negative effects of microplastic exposure on growth and development of Crepidula onyx

Nanoplastics Induce More Serious Microbiota Dysbiosis and Inflammation in the Gut of Adult Zebrafish than Microplastics

Microplastics (MPs) (< 5 mm) and nanoplastics (NPs) (< 100 nm) are emerging environmental pollutants and have been proved could cause a series of toxicity in aquatic organisms. In this study, the effects on gut microbiota of adult zebrafish exposed for 21 days to 10 μg/L and 1 mg/L of MPs (8 μm) and NPs (80 nm) were evaluated. We analyzed the intestinal microbial community of zebrafish using high throughput sequencing of the 16S rRNA gene V3-V4 region and also performed transcriptional profiling of the inflammation pathway related genes in the intestinal tissues. Our results showed that both spherical polystyrene MPs and NPs could induce microbiota dysbiosis in the gut of zebrafish. The flora diversity of gut microbiota significantly increased under a high concentration of NPs. At the phylum level, the abundance of Proteobacteria increased significantly and the abundance of Fusobacteria, Firmicutes and Verrucomicrobiota decreased significantly in the gut after 21-day exposure to 1 mg/L of both MPs and NPs. Furthermore, interestingly, the abundance of Actinobacteria decreased in the MPs treatment groups but increased in the NPs treatment groups. At the genus level, revealed that the relative abundance of Aeromonas significantly increased both in the MPs and NPs treatment groups. Moreover, it was observed that NPs increased mRNA levels of il8, il10, il1β and tnfα in the gut, but not in MPs exposure group, indicating that the NPs may have a more serious effect on the gut of zebrafish than MPs to induce microbiota dysbiosis and inflammation in the gut.

Ecological risks in a 'plastic' world: A threat to biological diversity?

Microplastics pollution is predicted to increase in the coming decades, raising concerns about its effects on living organisms. Although the effects of microplastics on individual organisms have been extensively studied, the effects on communities, biological diversity, and ecosystems remain underexplored. This paper reviews the published literature concerning how microplastics affect communities, biological diversity, and ecosystem processes. Microplastics increase the abundance of some taxa but decrease the abundance of some other taxa, indicating trade-offs among taxa and altered microbial community composition in both the natural environment and animals' gut. The alteration of community composition by microplastics is highly conserved across taxonomic ranks, while the alpha diversity of microbiota is often reduced or increased, depending on the microplastics dose and environmental conditions, suggesting potential threats to biodiversity. Biogeochemical cycles, greenhouse gas fluxes, and atmospheric chemistry, can also be altered by microplastics pollution. These findings suggest that microplastics may impact the U.N. Sustainability Development Goals (SDGs) to improve atmospheric, soil, and water quality and sustaining biodiversity.

Adverse biological effects of ingested polystyrene microplastics using Drosophila melanogaster as a model in vivo organism

The abundant presence and extensive use of polystyrene microplastics (PSMPs) has recently become a serious environmental concern, as impact of exposure to these substances on human health remains unknown. While in vitro studies yield data on adverse effect of PSMPs, in vivo approaches are more relevant for risk assessment. Drosophila melanogaster is one of the most genetically and experimentally accessible model organisms used in biology as an in vivo model. D. melanogaster was selected as a representative in vivo model organism to examine the genotoxic potential of PSMPs at 5 concentrations of three different sizes namely 4, 10, or 20 µm. In particular, the wing somatic mutation and recombination test (SMART), a scalable, time-efficient in vivo assay developed to study genotoxicity of various compounds in a rapid manner at low costs was used. The third-instar Drosophila larvae were exposed to PSMPs through food at 5 concentrations ranging from 0.01-10 mM. Viability (lethality), larval length, morphological deformations, locomotor activity (climbing behavior), and genotoxic effects were the end-points measured. Exposure to PSMPs at 4, 10, or 20 µm produced significant morphological defects, impaired climbing behavior, and genotoxicity as evidenced by the SMART test demonstrating induction of somatic recombination. Significant increases were observed in the frequency of total spots, suggesting that PSMPs might induce genotoxic activity predominantly via initiation of somatic DNA recombination in a concentration-dependent manner.

Comprehending the complexity of microplastic organismal exposures and effects, to improve testing frameworks

Microplastics (MPs) have been identified as a threat to global ecosystems. Current projections indicate that the negative impacts of MPs will increase in the environment. Traditional toxicity testing does not account for the diversity of MP particles, the inherent diversity in potential exposure routes, and complex impacts in exposed organisms. Here we present and discuss factors influencing organismal exposure to MPs driven by fate and behavior of MPs in different environmental matrices and organisms behavioral niches. We then provide a structured classification of potential effects of MPs, chemical or particulate, generic or specific to MPs. Using these analyses, we discuss appropriateness and limitations of applying traditional, chemical-based ecotoxicity testing for the study of MPs, and propose practical recommendations and guidelines. Future laboratory based studies can be improved to increase understanding of potential real world effects of MPs by careful selection of appropriate exposure systems and conditions, test organism, MP characteristics, endpoints and required controls. We build upon recommendations provided in previous publications and complement them with a list of parameters and practical information that should be checked and/or reported in MP studies.

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.

Parental transfer of nanopolystyrene-enhanced tris(1,3-dichloro-2-propyl) phosphate induces transgenerational thyroid disruption in zebrafish

Plastic is a globally recognized superwaste that can affect human health and wildlife when it accumulates and is amplified in the food chain. Microplastics (plastic particles < 5 mm) and nanoplastics (plastic particles < 100 nm) can interact with organic pollutants already present in the aquatic environment, potentially acting as carriers for pollutants entering organisms and thus influencing the bioavailability and toxicity of those pollutants. In this study, we investigated the transfer kinetics and transgenerational effects of exposure to tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and polystyrene nanoplastics (PS-NPs) in F1 offspring. At 90 days postfertilization, zebrafish (Danio rerio) strain AB was exposed to either TDCIPP (0, 0.47, 2.64, or 12.78 μg/L) or PS-NPs (10 mg/L) or their combination for 120 days. The results showed that TDCIPP and PS-NPs accumulated in the gut, gill, head, and liver of the zebrafish in a sex-dependent manner. The presence of PS-NPs promoted the bioaccumulation of TDCIPP in the adult fish and increased the parental transfer of TDCIPP to their offspring. We demonstrate that parental exposure to TDCIPP alone or in combination with PS-NPs induces thyroid disruption in adults, and then leads to thyroid endocrine disruption in their larval offspring. Reduced thyroxine (T4) and 3,5,3'-triiodothyronine (T3) levels contributed to the observed transgenerational thyroid dysfunction, which inhibited developmental growth and disturbed the transcription of genes and expression of proteins involved in the hypothalamic-pituitary-thyroid (HPT) axis in the F1 larvae. The increased transfer of TDCIPP to the offspring in the presence of PS-NPs also enhanced transgenerational thyroid endocrine disruption, demonstrated by a further reduction in T4 and the upregulation of thyroglobulin (tg), uridine diphosphate-glucuronosyltransferase (ugt1ab), thyroid-stimulating hormone (tshβ), and thyroid hormone receptor (trα) expression in the F1 larvae compared with the effects of parental TDCIPP exposure alone. Overall, our results indicate that the presence of PS-NPs modifies the bioavailability of TDCIPP and aggravates transgenerational thyroid disruption in zebrafish.

Seasonal characteristics of microplastics ingested by copepods in Jiaozhou Bay, the Yellow Sea

Microplastics (MPs) are a growing threat to marine biota and ecosystems, and zooplankton are at high risk of ingesting MPs. The seasonal changes in MPs in zooplankton and the key environmental factors influencing the retention of MPs in zooplankton are largely unknown. For the first time, the characteristics of MPs in copepods across four seasons in Jiaozhou Bay. The abundance, shape, size, and chemical composition of the MPs in copepods were investigated, and the relationships between the MP/copepod value and key environmental factors were analyzed. The results revealed a significant seasonal difference in MP/copepod values in Jiaozhou Bay. MP/copepod values were 0.26, 0.23, 0.14 and 0.16 in February, May, August and November, respectively. The MP/copepod value was significantly higher in winter and spring than in summer and significantly higher in the estuarine zone than in other zones. Seawater temperature was negatively correlated with the MP/copepod value. No significant seasonal differences were detected in the characteristics of MPs in copepods in Jiaozhou Bay. The size of MPs in copepods ranged from 90 to 2485 μm, with an average of 454 ± 376 μm. Fiber MPs were the most risky to copepods, accounting for 92% of the total ingested MPs. In terms of the chemical composition of the MPs, a total of 11 polymers were detected in copepods in Jiaozhou Bay in the four seasons. The main components were polyester and cellophane (41.9% and 25.7%, respectively). This study provides the key parameters of the MPs in copepods in Jiaozhou Bay and is an important basis for further ecological risk assessments of MPs. The chronic effects of low-level MP retention on copepods, the impact of fibers on copepods, and appropriate assessments of MP risk under different environmental conditions are recommended as research topics for the next step toward developing an environmentally relevant MP risk assessment. THE MAIN FINDING: The seasonal characteristics of microplastics ingested by copepods in Jiaozhou Bay were revealed.

A fish tale: a century of museum specimens reveal increasing microplastic concentrations in freshwater fish

Plastic is pervasive in modern economies and ecosystems. Freshwater fish ingest microplastics (i.e., particles <5 mm), but no studies have examined historical patterns of their microplastic consumption. Measuring the patterns of microplastic pollution in the past is critical for predicting future trends and for understanding the relationship between plastics in fish and the environment. We measured microplastics in digestive tissues of specimens collected from the years 1900-2017 and preserved in museum collections. We collected new fish specimens in 2018, along with water and sediment samples. We selected four species: Micropterus salmoides (largemouth bass), Notropis stramineus (sand shiner), Ictalurus punctatus (channel catfish), and Neogobius melanostomus (round goby) because each was well represented in museum collections, are locally abundant, and collected from urban habitats. For each individual, we dissected the digestive tissue from esophagus to anus, subjected tissue to peroxide oxidation, examined particles under a dissecting microscope, and used Raman spectroscopy to characterize the particles' chemical composition. No microplastics were detected in any fish prior to 1950. From mid-century to 2018, microplastic concentrations showed a significant increase when data from all fish were considered together. All detected particles were fibers, and represented plastic polymers (e.g., polyester) along with mixtures of natural and synthetic textiles. For the specimens collected in 2018, microplastics in fish and sediment showed similar patterns across study sites, while water column microplastics showed no differences among locations. Overall, plastic pollution in common freshwater fish species is increasing and pervasive across individuals and species, and is likely related to changes in environmental concentrations. Museum specimens are an overlooked source for assessing historical patterns of microplastic pollution, and for predicting future trends in freshwater fish, thereby helping to sustain the health of commercial and recreational fisheries worldwide.

How do humans recognize and face challenges of microplastic pollution in marine environments? A bibliometric analysis

Microplastics (MPs) are abundant in marine environments, drawing global attention from scientists and rendering it significant to review the research progress and predict future trends of this field. To achieve that, we collected 1898 publications on marine MPs from Web of Science and performed a bibliometric analysis by CiteSpace and VOSviewer. Additionally, we utilized an unrestricted retrieval of literature from ScienceDirect to supplement our major findings. Trends in publication numbers show the growth in study from the initial stage ( 2012 and before), when microplastic (MP) occurrence, abundance, and distribution were primarily investigated. Throughout the ascent stage (between 2013-2016), when diverse sampling and analytical methods were applied to capture and identify MPs from the ocean, baseline data have been gleaned on physiochemical properties of MPs. The research focus then shifted to the bioaccumulation and ecotoxicological effects of MPs on marine biota, further highlighting their potential deleterious impacts on human health via dietary exposure, and this period was defined as the exploration stage (2017 and onwards). Nevertheless, key challenges including the lack of standard procedures for MP sampling, technical limitations in MP detecting and identification, and controversy about the underlying effects on the marine ecosystems and humans have also been arisen in the last decade. The present study elucidates how we gradually recognize MP pollution in marine environments and what challenges we face, suggesting future avenues for MP research.

Microplastic ingestion induces asymmetry and oxidative stress in larvae of the sea urchin Pseudechinus huttoni

Determining the effects of microplastic (MP) ingestion by marine organisms, especially during the sensitive larval stages, is an important step in understanding wider ecosystem responses. We investigated the ingestion, retention (1-5 μm), and short-term exposure effects (1-4 μm) of spherical MPs by larvae of the sea urchin Pseudechinus huttoni. Larvae ingested MPs in a dose-dependent manner and successfully egested particles after a short retention period. Survival was not significantly affected by exposure to MPs over the 10-day experimental period, however, a teratogenic response in terms of delayed development resulted in an increase of larval arm asymmetry. Additionally, MP exposure resulted in oxidative damage to lipids and proteins in larval body tissue despite a significant upregulation of antioxidant defences. The findings indicate MP exposure may impair cellular function, leading to negative consequences for an organism's fitness and survival.

Dietary exposure to polyethylene terephthalate microplastics (PET-MPs) induces faster growth but not oxidative stress in the giant snail Achatina reticulata

Polyethylene terephthalate (PET) is one of the main plastic polymers contaminating natural ecosystems. Although PET microplastics (PET-MPs) have been found in both aquatic and terrestrial ecosystems, the information concerning their potential toxicity towards terrestrial organisms is limited. The present study aimed at investigating the ingestion and the possible adverse effects induced by a 40-days exposure to irregular shaped PET-MPs toward the giant snail Achatina reticulata. Giant snails were exposed via the diet to two concentrations (1% and 10% w/w; i.e., g of PET-MPs/g of the administered food) of PET-MPs and their capability to ingest and egest PET-MPs was assessed together with an evaluation of their potential effects at biochemical and individual levels. Oxidative stress-related biomarkers (i.e., the amount of reactive oxygen species, the activity of antioxidant enzymes and lipid peroxidation) and DNA fragmentation were measured in the digestive gland isolated from snails as biochemical endpoints. Changes in growth trajectories, in terms of body weight and shell size, were considered as morphometric endpoints. Our results demonstrated that A. reticulata can efficiently ingest and egest PET-MPs. Whilst giant snails did not experience an oxidative stress condition, significant changes in their growth trajectories were observed, with PET-MPs-treated snails grew more and more quickly than the control group. Our results suggest that PET-MPs might represent a risk during early-life stages for terrestrial organisms.

Effect of microplastics in water and aquatic systems

Surging dismissal of plastics into water resources results in the splintered debris generating microscopic particles called microplastics. The reduced size of microplastic makes it easier for intake by aquatic organisms resulting in amassing of noxious wastes, thereby disturbing their physiological functions. Microplastics are abundantly available and exhibit high propensity for interrelating with the ecosystem thereby disrupting the biogenic flora and fauna. About 71% of the earth surface is occupied by oceans, which holds 97% of the earth's water. The remaining 3% is present as water in ponds, streams, glaciers, ice caps, and as water vapor in the atmosphere. Microplastics can accumulate harmful pollutants from the surroundings thereby acting as transport vectors; and simultaneously can leach out chemicals (additives). Plastics in marine undergo splintering and shriveling to form micro/nanoparticles owing to the mechanical and photochemical processes accelerated by waves and sunlight, respectively. Microplastics differ in color and density, considering the type of polymers, and are generally classified according to their origins, i.e., primary and secondary. About 54.5% of microplastics floating in the ocean are polyethylene, and 16.5% are polypropylene, and the rest includes polyvinyl chloride, polystyrene, polyester, and polyamides. Polyethylene and polypropylene due to its lower density in comparison with marine water floats and affect the oceanic surfaces while materials having higher density sink affecting seafloor. The effects of plastic debris in the water and aquatic systems from various literature and on how COVID-19 has become a reason for microplastic pollution are reviewed in this paper.

Effects of Microplastics, Polystyrene, and Polyethylene on Antioxidants, Metabolic Enzymes, HSP-70, and Myostatin Expressions in the Giant River Prawn Macrobrachium rosenbergii: Impact on Survival and Growth

This study was conducted to understand the biological effects of microplastics (MPs), polystyrene microspheres (PSM), and polyethylene microparticles (PEM) in the juveniles of the giant river prawn, Macrobrachium rosenbergii. The PSM (0.5-1.0 µm) and PEM (30.0-150.0 µm) were separately incorporated into the artificial diets with concentrations of 1, 5, and 10 mg per 100 g. The prawns were fed with these diets for a period of 60 days. Compared with control, the following dose-dependent changes have been recorded in PSM and PEM incorporated feeds fed prawns: declines in the survival rate, length and weight gains; increase in activities of antioxidant enzymes, such as superoxide dismutase, catalase, glutathione s-transferase, and glutathione peroxidase (GPx); elevated concentrations of reduced glutathione (GSH) and malondialdehyde; decreased activities of metabolic enzymes, such as glutamic oxaloacetic transaminase and glutamic pyruvic transaminase; higher total RNA in hepatopancreas (HP) of PSM fed prawns compared with that of PEM; higher total RNA in muscle (MU) of PEM-fed prawns compared with that of PSM; prominent cDNA bands in 150 bp regions; up-regulated heat shock protein (HSP70) gene in HP; down-regulation of HSP70 gene in MU of PSM-fed prawns only; down-regulated myostatin (MSTN) gene. These results suggest that these MPs have affected the survival and growth, activated the antioxidant defense, inhibit the metabolic enzymes, positively regulated the HSP70 gene, and negatively regulated the MSTN gene in M. rosenbergii. Therefore, exposures to PSM and PEM caused biological effects in this species of prawn.

Linking effects of microplastics to ecological impacts in marine environments

Recently, efforts to determine the ecological impacts of microplastic pollutants have increased because of plastic's accelerated contamination of the environment. The tiny size, variable surface topography, thermal properties, bioavailability and biological toxicity of microplastics all offer opportunities for these pollutants to negatively impact the environment. Additionally, various inorganic and organic chemicals sorbed on these particles may pose a greater threat to organisms than the microplastics themselves. However, there is still a big knowledge gap in the assessment of various toxicological effects of microplastics in the environment. Ecological risk assessment of microplastics has become more challenging with the current data gaps. Thus, a current literature review and identification of the areas where research on ecology of microplastics can be extended is necessary. We have provided an overview of various aspects of microplastics by which they interact negatively or positively with marine organisms. We hypothesize that biogeochemical interactions are critical to fully understand the ecological impacts, movement, and fate of microplastics in oceans. As microplastics are now ubiquitous in marine environments and impossible to remove, we recommend that it's not too late to converge research on plastic alternatives. In addition, strict actions should be taken promptly to prevent plastics from entering the environment.

The combined exposure of microplastics and toxic contaminants in the floodplains of north India: A review

Microplastics in aquatic ecosystem are an emerging environmental threat, primarily aggregating into sediments and living biota besides providing active transportation to toxic pollutants. Recent studies have revealed that a microplastic surface cannot be considered as "inert" and therefore the rate and stage of degradation of microplastic will determine its capability in adsorbing and transporting the solute to longer distances. Our concern is driven by the fact that there has been an absence of widescale research in India despite a country with one of the longest networks of rivers and a 7500 km long active coastline. Anthropogenic pollutants are expected to increase and the situation will further worsen when more persistent organic pollutants (POCs) and geogenic contaminants will find its sink via monsoon runoff. Studies on aquatic species including COD, daphnia magna and zebrafish suggest strong links of bio-accumulation, suspecting to a more serious situation for the coastal India where there is an almost three times increase in the density of the microplastics as the monsoon progresses. Evidences also suggests that microplastics can adsorb known carcinogens as well as endocrine disrupting chemicals leaving our aquatic life exposed to higher mortality. Our review is a first ever scientific attempt in compiling these evidences through researches done in this field to understand the risk that the major floodplains of North India are currently facing. We have adapted the theories and inferences of the available research to predict and postulate a probable mechanism that could explain the severity of the situation in India.

Developmental toxicity of plastic leachates on the sea urchin Paracentrotus lividus

Microplastic pollution has become ubiquitous, affecting a wide variety of biota. Although microplastics are known to alter the development of a range of marine invertebrates, no studies provide a detailed morphological characterisation of the developmental defects. Likewise, the developmental toxicity of chemicals leached from plastic particles is understudied. The consequences of these developmental effects are likely underestimated, and the effects on ecosystems are unknown. Using the sea urchin Paracentrotus lividus as a model, we studied the effects of leachates of three forms of plastic pellet: new industrial pre-production plastic nurdles, beached pre-production nurdles, and floating filters, known as biobeads, also retrieved from the environment. Our chemical analyses show that leachates from beached pellets (biobead and nurdle pellets) and highly plasticised industrial pellets (PVC) contain polycyclic aromatic hydrocarbons and polychlorinated biphenyls, which are known to be detrimental to development and other life stages of animals. We also demonstrate that these microplastic leachates elicit severe, consistent and treatment-specific developmental abnormalities in P. lividus at embryonic and larval stages. Those embryos exposed to virgin polyethylene leachates with no additives nor environmental contaminants developed normally, suggesting that the abnormalities observed are the result of exposure to either environmentally adsorbed contaminants or pre-existing industrial additives within the polymer matrix. In the light of the chemical contents of the leachates and other characteristics of the plastic particles used, we discuss the phenotypes observed during our study, which include abnormal gastrulation, impaired skeletogenesis, abnormal neurogenesis, redistribution of pigmented cells and embryo radialisation.

Microplastic leachates induce species-specific trait strengthening in intertidal mussels

Plastic pollution is ubiquitous with increasing recognition of its direct effects on species' fitness. Little is known, however, about its more subtle effects, including the influence of plastic pollution on the morphological, functional and behavioral traits of organisms that are central to their ability to withstand disturbances. Among the least obvious but most pernicious forms of plastic-associated pollution are the chemicals that leach from microplastics. Here, we investigate how such leachates influence species' traits by assessing functional trait compensation across four species of intertidal mussels, through investigations of byssal thread production, movement and aggregation behavior for mussels held in natural seawater or seawater contaminated by microplastic leachates. We found no evidence for compensation of functional traits, but for each species, microplastic leachates reinforced one trait while others remained unaffected. Two species (Perna perna and Mytilus galloprovincialis), were characterized by a resistance strategy to disturbance; they produced more byssal threads in microplastic leachate seawater than in control seawater, while motility and aggregation remained essentially unaffected. In contrast, the other two species (M. edulis and Choromytilus meridionalis), showed a resilience strategy to disturbance through increased motility and aggregation in leachate seawater, while byssal thread production remained unaffected. These results suggest that the competitive abilities of intertidal mussels may be related to their sensitivity to microplastic leachates or other chemical disturbance. Importantly, the trait strengthening observed will affect the ability of these mussels to form spatially patterned beds, with implications for their quality as autogenic ecological engineers or foundation species. Thus, our findings have implications for the ability of mussel beds to tolerate disturbance, and hence for central ecosystem services, such as their ability to support biodiversity and enhance secondary and tertiary production. The results suggest that an inconspicuous aspect of plastic pollution has the potential to influence other communities and ecosystems in powerful ways.

Potential effects of biodegradable single-use items in the sea: Polylactic acid (PLA) and solitary ascidians

With conventional plastics posing a great threat to marine organisms, and potentially also to humans, bio-based, biodegradable plastics are being offered as an ecological solution by which to reduce the environmental impact. Inside compost facilities, bioplastics that comply with the EN 13432:2000 international standard biodegrade almost completely within 180 days. However, outside compost facilities, and specifically in marine environments, these bioplastics may have a similar effect to that of fossil-fuel based plastics. Here we investigated the effects of polyethylene terephthalate (PET) and polylactic acid (PLA) single-use cups and plates on a solitary ascidian's biological and ecological features. Both PET and PLA microparticles reduced the fertilization rate of Microcosmus exasperatus, with no significant difference between materials. Accumulation rates in adult M. exasperatus exposed to micronized PET and PLA particles at two concentrations were similar for both the bioplastic material and the conventional plastic particles, with no significant difference between the two materials. A microbial-based digestive protocol was developed in order to recover the bioplastic material from ascidian tissue and reduce any material-loss caused by the known digestion protocols. Finally, PET plates submerged for three months in the Red Sea exhibited a significantly higher community richness and cover area in comparison to PLA plates, which did not provide a firm substrate for settlers. Indeed, coverage by the solitary ascidian Herdmania momus was significantly higher on PET plates. The current study demonstrates that discarded bioplastic products may have similar effects to those of conventional plastics on marine organism fertilization and biological accumulation, emphasizing the need to revise both the production and marketing of "biodegradable" and "compostable" plastics in order to prevent a further negative impact on ecosystems due to the mismanagement of bioplastic products.

Ingestion and toxicity of microplastics in the freshwater gastropod Lymnaea stagnalis: No microplastic-induced effects alone or in combination with copper

The interaction of microplastics with freshwater biota and their interaction with other stressors is still not very well understood. Therefore, we investigated the ingestion, excretion and toxicity of microplastics in the freshwater gastropod Lymnaea stagnalis. MP ingestion was analyzed as tissues levels in L. stagnalis after 6-96 h of exposure to 5-90 μm spherical polystyrene (PS) microplastics. To understand the excretion, tissue levels were determined after 24 h of exposure followed by a 12 h-7 d depuration period. To assess the toxicity, snails were exposed for 28 d to irregular PS microplastics (<63 μm, 6.4-100,000 particles mL^-1), both alone and in combination with copper as additional stressor. To compare the toxicity of natural and synthetic particles, we also included diatomite particles. Microplastics ingestion and excretion significantly depended on the particle size and the exposure/depuration duration. An exposure to irregular PS had no effect on survival, reproduction, energy reserves and oxidative stress. However, we observed slight effects on immune cell phagocytosis. Exposure to microplastics did not exacerbate the reproductive toxicity of copper. In addition, there was no pronounced difference between the effects of microplastics and diatomite. The tolerance towards microplastics may originate from an adaptation of L. stagnalis to particle-rich environments or a general stress resilience. In conclusion, despite high uptake rates, PS fragments do not appear to be a relevant stressor for stress tolerant freshwater gastropods considering current environmental levels of microplastics.

Characteristics of microplastics in shoreline sediments from a tropical and urbanized beach (Da Nang, Vietnam)

Microplastics in shoreline sediments were investigated from Da Nang beach for the first time. Sediment samples at the two depth strata (0-5 cm and 5-10 cm) at eight sites along the entire coast were collected for identifying the characteristics of microplastics, including their concentration, size, shape, color, and nature. The synthetic fiber was the predominant type of microplastics, accounting for 99.2% of the total items. Blue (59.9%) and white (22.9%) were the most common colors of the fibers. Synthetic fibers showed a homogenous distribution at all sampling sites with a mean concentration of 9238 ± 2097 items kg^-1 d.w. Meanwhile, the fibers tended to concentrate much more at the surface stratum than the deeper stratum. A large number of synthetic fibers (81.9%) were in the size range of 300-2600 μm, which might pose a threat to marine biota and human health.

Risks of floating microplastic in the global ocean

Despite the ubiquitous and persistent presence of microplastic (MP) in marine ecosystems, knowledge of its potential harmful ecological effects is low. In this work, we assessed the risk of floating MP (1 μm-5 mm) to marine ecosystems by comparing ambient concentrations in the global ocean with available ecotoxicity data. The integration of twenty-three species-specific effect threshold concentration data in a species sensitivity distribution yielded a median unacceptable level of 1.21 ∗ 10⁵ MP m^-³ (95% CI: 7.99 ∗ 10³-1.49 ∗ 10⁶ MP m^-³). We found that in 2010 for 0.17% of the surface layer (0-5 m) of the global ocean a threatening risk would occur. By 2050 and 2100, this fraction increases to 0.52% and 1.62%, respectively, according to the worst-case predicted future plastic discharge into the ocean. Our results reveal a spatial and multidecadal variability of MP-related risk at the global ocean surface. For example, we have identified the Mediterranean Sea and the Yellow Sea as hotspots of marine microplastic risks already now and even more pronounced in future decades.

Differential modulation of oxidative stress, antioxidant defense, histomorphology, ion-regulation and growth marker gene expression in goldfish (Carassius auratus) following exposure to different dose of virgin microplastics

Goldfish (Carassius auratus) juveniles were exposed to virgin polyvinyl chloride microplastics (PVC-MPs) in triplicate at 0, 0.1 or 0.5 mg/L for four days. Afterwards, the histopathology of the gills, liver and intestines were examined, along with various antioxidant enzymes and indicators of oxidative damage (malondialdehyde (MDA) and hydrogen peroxide (H₂O₂)), in the brain, liver and gills. In addition, we also studied the expression of hepatic insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein 1 (IGFBP-1) and growth hormone (GH) receptor, while cortisol receptor (CR) and cytochrome P450 1A (CYP1A) gene expression were assayed in both the liver and gills. Histological analysis revealed PVC-MPs in the intestines at 0.1 and 0.5 mg/L, along with substantially shorter villi. The gills appeared undamaged by PVC-MPs exposure and had limited or no effect to antioxidant activity, Na⁺/K⁺-ATPase and H⁺-ATPase activity or plasma ion levels, but there was a prominent upsurge of the detoxification enzymes glutatione S-transferase (GST) activity and CYP1A expression. Livers showed inflammation and some occurrences of hemorrhaging and necrosis at 0.5 mg/L. While the brain showed some evidence of oxidative damage, the liver was the most susceptible to oxidative damage, based on increased MDA, H₂O₂ and various antioxidant enzymes. Hepatic expression of IGFBP-1 and GH receptor were significantly downregulated at 0.5 mg/L while CR was upregulated. Results indicate that exposure to environmentally relevant PVC-MP can cause oxidative damage in the brain and liver, adverse histomorphological changes to the intestine and liver and alter the gene expression in goldfish.

Intergenerational microplastics impact the intertidal barnacle Amphibalanus amphitrite during the planktonic larval and benthic adult stages

Microplastic exposure in one generation of marine organism is believed to impact future generations; the nature of this impact, however, remains unclear, especially across different life stages. We investigated within-generational, latent, and intergenerational effects of various sizes (1.7, 6.8, 10.4, and 19.0 μm) and concentrations (1, 10, 100, and 1000 beads mL^-1) of polystyrene microplastics on the planktonic larval and benthic adult life stages of the intertidal barnacle Amphibalanus amphitrite. We exposed parents to microplastics during different developmental stages and examined the life history traits of their offspring. Microplastics had prominent intergenerational-but no within-generational-effects. Parental exposure to 1.7, 6.8, and 10.4 μm microplastics from the larvae to adults significantly increased offspring larval mortality. 1.7 and 6.8 μm microplastics at 1000 beads mL^-1 delayed larval development in offspring. Intergenerational effects were observed when microplastics were exposed to parent larvae, suggesting that parental experiences during sensitive early-life stages can have profound impacts across generations. Adverse intergenerational effects of microplastics might drastically reduce larval recruitment and threaten long-term zooplankton sustainability.

Impacts of microplastics exposure on mussel (Mytilus edulis) gut microbiota

Microplastics (MPs), plastics with particles smaller than 5 mm, have been found almost in every corner of the world, especially in the ocean. Due to the small size, MPs can be ingested by animals and enter the marine trophic chain. MPs can affect animal health by physically causing damage to the digestive tract, leaking plastic chemical components, and carrying environmental pollutants and pathogens into animals. In this study, impacts of MPs ingestion on gut microbiota were investigated. Filter feeding mussels were exposed to "virgin" and "weathered" MPs at relatively realistic concentration 0.2 mg L^-1 ("low") and exaggerated concentration 20 mg L^-1 ("high") for 6 weeks. Influence in mussel gut microbiota was investigated with 16S rRNA gene high-throughput sequencing. As compared with non-exposed mussels, alteration of gut microbiota was observed after mussels were exposed to MPs for 1 week, 3 weeks, 6 weeks, and even after 8-day post-exposure depuration. Potential human pathogens were found among operational taxonomic units (OTUs) with increased abundance induced by MP-exposure. Faecal pellets containing microorganisms from altered gut microbiota and MPs might further influence microbiota of surrounding environment. Our results have demonstrated impacts of MP-exposure on mussel gut microbiota and suggested possible consequent effects on food quality, food safety, and the well-being of marine food web in the ecosystem for future studies.

Microplastics in the environment: Interactions with microbes and chemical contaminants

Microplastics (MPs) are contaminants of emerging concern that have gained considerable attention during the last few decades due to their adverse impact on living organisms and the environment. Recent studies have shown their ubiquitous presence in the environment including the atmosphere, soil, and water. Though several reviews have focused on the occurrence of microplastics in different habitats, little attention has been paid to their interaction with biological and chemical pollutants in the environment. This review therefore presents the state of knowledge on the interaction of MPs with chemicals and microbes in different environments. The distribution of MPs, the association of toxic chemicals with MPs, microbial association with MPs and the microbial-induced fate of MPs in the environment are discussed. The biodegradation and bioaccumulation of MPs by and in microbes and its potential impact on the food chain are also reviewed. The mechanisms driving these interactions and how these, in turn, affect living organisms however are not yet fully understood and require further attention.

Bioaccumulation and biomagnification of microplastics in marine organisms: A review and meta-analysis of current data

Microplastic (MP) contamination has been well documented across a range of habitats and for a large number of organisms in the marine environment. Consequently, bioaccumulation, and in particular biomagnification of MPs and associated chemical additives, are often inferred to occur in marine food webs. Presented here are the results of a systematic literature review to examine whether current, published findings support the premise that MPs and associated chemical additives bioaccumulate and biomagnify across a general marine food web. First, field and laboratory-derived contamination data on marine species were standardised by sample size from a total of 116 publications. Second, following assignment of each species to one of five main trophic levels, the average uptake of MPs and of associated chemical additives was estimated across all species within each level. These uptake data within and across the five trophic levels were then critically examined for any evidence of bioaccumulation and biomagnification. Findings corroborate previous studies that MP bioaccumulation occurs within each trophic level, while current evidence around bioaccumulation of associated chemical additives is much more ambiguous. In contrast, MP biomagnification across a general marine food web is not supported by current field observations, while results from the few laboratory studies supporting trophic transfer are hampered by using unrealistic exposure conditions. Further, a lack of both field and laboratory data precludes an examination of potential trophic transfer and biomagnification of chemical additives associated with MPs. Combined, these findings indicate that, although bioaccumulation of MPs occurs within trophic levels, no clear sign of MP biomagnification in situ was observed at the higher trophic levels. Recommendations for future studies to focus on investigating ingestion, retention and depuration rates for MPs and chemical additives under environmentally realistic conditions, and on examining the potential of multi-level trophic transfer for MPs and chemical additives have been made.

Bioavailability of Microplastics to Marine Zooplankton: Effect of Shape and Infochemicals

The underlying mechanisms that influence microplastic ingestion in marine zooplankton remain poorly understood. Here, we investigate how microplastics of a variety of shapes (bead, fiber, and fragment), in combination with the algal-derived infochemicals dimethyl sulfide (DMS) and dimethylsulfoniopropionate (DMSP), affect the ingestion rate of microplastics in three species of zooplankton, the copepods Calanus helgolandicus and Acartia tonsa and larvae of the European lobster Homarus gammarus. We show that shape affects microplastic bioavailability to different species of zooplankton, with each species ingesting significantly more of a certain shape: C. helgolandicus-fragments (P < 0.05); A. tonsa-fibers (P < 0.01); H. gammarus larvae-beads (P < 0.05). Thus, different feeding strategies between species may affect shape selectivity. Our results also showed significantly increased ingestion rates by C. helgolandicus on all microplastics that were infused with DMS (P < 0.01) and by H. gammarus larvae and A. tonsa on DMS-infused fibers and fragments (P < 0.05). By using a range of more environmentally relevant microplastics, our findings highlight how the feeding strategies of different zooplankton species may influence their susceptibility to microplastic ingestion. Furthermore, our novel study suggests that species reliant on chemosensory cues to locate their prey may be at an increased risk of ingesting aged microplastics in the marine environment.

Microplastics in waters and soils: Occurrence, analytical methods and ecotoxicological effects

Microplastics (MPs) are ubiquitous in the environment and more abundant in the marine environment. Consequently, increasing focus has been put on MPs in oceans and seas, while little importance has been attached to their presence in freshwaters and soils. Therefore, this paper aimed to provide a comprehensive review of the occurrence, analysis and ecotoxicology of MPs. The abundance and distribution of MPs in several typical freshwater systems of China were summarized. It suggested that the surface water of Poyang Lake contained the highest concentration of 34 items/L MPs among all the 8 freshwater systems, and the content of MPs in sediments were higher than that of the surface water. Net-based zooplankton sampling methods are the most frequently utilized sampling methods for MPs, and density separation, elutriation and digestion are three major pretreatment methods. Fourier transform infrared spectroscopy, Raman spectroscopy and pyrolysis-gas chromatography coupled to mass spectrometry are often used to identify the polymer types of MPs. Besides, MPs might damage the digestive tract of various organisms and negatively inhibit their growth, feeding and reproduction. The ways of human exposure to MPs are by ingestion, inhalation and dermal exposure, digestive and respiratory system might be adversely influenced. However, potential health risks of MPs to humans are remained insufficiently researched. Overall, by showing the presence of MPs in freshwaters and soils as well as possible ecotoxicological effects on the environment and humans, this paper provided a framework for future research in this field.

Invertebrate responses to microplastic ingestion: Reviewing the role of the antioxidant system

Microplastic ingestion in invertebrates reduces somatic and reproductive growth. This could be caused by energy reserves being detracted from growth processes and redistributed to maintenance processes that preserve life. A potential sink for this diverted energy is the antioxidant system, which minimises oxidative damage and reinstates redox homeostasis following disturbances caused by exposure to pollution. Several microplastic studies have used genetic and molecular redox biomarkers to assess how microplastic ingestion affects the functioning of the antioxidant system. This systematic review synthesises the current understanding of redox biomarker responses in invertebrates that have ingested microplastics. We found that biomarker response information exists for only seven invertebrate taxa, and early life stages have received little scientific attention. The microplastics used by most studies were polystyrene (45% of studies), spherical (51% of studies), and were < 10 μm in diameter (31% of studies). We found multiple examples of microplastic ingestion posing an oxidative challenge to invertebrates, which required upregulation of antioxidant system components. However, the lack of systematic experiments prevented us from clearly identifying which characteristic of microplastics caused these responses. We identify several areas for consideration when investigating biomarker responses to microplastic ingestion and offer research priorities for future studies.

Health impacts of environmental contamination of micro- and nanoplastics: a review

Plastics are extensively used in our daily life. However, a significant amount of plastic waste is discharged to the environment directly or via improper reuse or recycling. Degradation of plastic waste generates micro- or nano-sized plastic particles that are defined as micro- or nanoplastics (MNPs). Microplastics (MPs) are plastic particles with a diameter less than 5 mm, while nanoplastics (NPs) range in diameter from 1 to 100 or 1000 nm. In the current review, we first briefly summarized the environmental contamination of MNPs and then discussed their health impacts based on existing MNP research. Our review indicates that MNPs can be detected in both marine and terrestrial ecosystems worldwide and be ingested and accumulated by animals along the food chain. Evidence has suggested the harmful health impacts of MNPs on marine and freshwater animals. Recent studies found MPs in human stool samples, suggesting that humans are exposed to MPs through food and/or drinking water. However, the effect of MNPs on human health is scarcely researched. In addition to the MNPs themselves, these tiny plastic particles can release plastic additives and/or adsorb other environmental chemicals, many of which have been shown to exhibit endocrine disrupting and other toxic effects. In summary, we conclude that more studies are necessary to provide a comprehensive understanding of MNP pollution hazards and also provide a basis for the subsequent pollution management and control.

First evidence of microplastics bioaccumulation by marine organisms in the Port Blair Bay, Andaman Islands

Microplastic (MP) pollution has become a global concern. We aim to quantify the extent of MP pollution in the coastal ecosystem of the Port Blair Bay, A&N Islands. Water, sediment, zooplankton, finfish, and shellfish samples were collected from the Port Blair Bay and analyzed for the presence of MP. Average concentrations of MP in water, sediment, zooplankton, finfish, and shellfishes were found to be 0.93 ± 0.59 particles per m³, 45.17 ± 25.23 particles per kilogram, 0.12 ± 0.07 pieces per zooplankter and 10.65 ± 7.83 particles per specimen, respectively. High amount of MP retention was observed in the zooplankton community. Maximum MP ingestion was observed in adult Carangoides malabaricus. Fiber was most abundant in water, sediment, and fish samples, followed by fragment and pellet. However, fragments were predominant in zooplankton. Nylon, acrylic, and ionomer surlyn were most abundant polymer types in the bay environment. These results demand further attention to combat plastic pollution in the coastal ecosystem.

An effective method for evaluation of microplastic contaminant in gastropod from Taihu Lake, China

Microplastics are ubiquitous in the environment. The isolation and characterization of microplastics can change, enabling science to elucidate the fate of microplastics in organisms. The main objective of the present study was to develop a rapid and effective method for the isolation, characterization, and quantification of microplastics from gastropod, and then evaluate the microplastic pollution in wild freshwater snails using the developed method. The whole tissue of gastropod Bellamya aeruginosa was spiked with microplastics derived from cosmetic products to optimize the tissue digestion and microplastic identification process. Optimum digestion of soft tissue was performed using a mixture of Tris-HCl, proteinase K, and KOH. Recovery of microplastics from the tissue digests, as determined by microscopy and infrared spectroscopy, was 89 ± 5%. The entire procedure could be completed within 30 h. Application of the procedure to wild freshwater snail B. aeruginosa collected from Taihu Lake revealed that 90~100% of the sampled snails accumulated 1 to 4 types of microplastics including poly(vinyl acetate), polyethylene terephthalate, polystyrene, and polyamides. In summary, a quick method was developed for the isolation and identification of microplastics from gastropod tissues, and the application of the method revealed the presence of microplastics in snails inhabiting Taihu Lake, China.

Effects of polystyrene microplastics on larval development, settlement, and metamorphosis of the intertidal barnacle Amphibalanus amphitrite

The effects of microplastic on mortality and sublethal responses on larval development of meroplankton are still largely unknown. Present study investigated the effects of four sizes of virgin spherical polystyrene microplastics (diameter 1.7, 6.8, 10.4, 19.0 μm) on naupliar (stage II-VI) and cypris larvae of barnacle Amphibalanus amphitrite at environmentally relevant concentrations (1, 10, 100, 1000 beads mL^-1). Essential life-history traits, including mortality, development time and rates of growth, settling, and metamorphosis were measured throughout the entire larval development. Feeding experiments were conducted to evaluate if microplastics decreased naupliar feeding due to physical impacts or selective feeding of nauplii. The results showed that A. amphitrite stage II nauplii were able to ingest and efficiently egest all sizes of microplastics. All the life-history endpoints measured were not significantly affected by all sizes of microplastics at any concentration tested. Presence of all sizes of microplastics did not cause physical interference on naupliar feeding and all stages of nauplius larvae (stage III-VI) did not selectively feed on microplastics. However, the feeding ability of stage III nauplius appeared to be affected by 1.7 μm at 1000 beads mL^-1 which was possibly due to individual variations rather than microplastics' impacts. Overall, the full larval development of barnacle A. amphitrite was not affected by microplastics at environmentally relevant concentrations under laboratory condition.

Toxicity comparison of nano-sized and micron-sized microplastics to Goldfish Carassius auratus Larvae

Plastic pollution is one of the most serious environmental issues worldwide. The negative influence of plastics on aquatic organisms has increasingly concerned, especially the influence of microplastic (MPs). In the present study, the toxicology of nano-sized MPs (nMPs) and micron-sized MPs (mMPs) were comparatively studied. Goldfish larvae were exposed to 10, 100 and 1000 μg/L nMPs and mMPs for 1, 3 and 7 days. The enrichment of MPs, body length, heart rate, motor ability, microscopic and ultrastructure of intestine, liver, gill and muscle tissue, as well as the oxidative stress were analyzed. Results showed that both 70 nm and 50 μm MPs were accumulated in the digestive tract of larvae. MPs at high concentrations could induce oxidative stress, destroy intestine, liver and gill tissues, increase heart rate, and inhibit growth and swimming speed of the larvae. The most important finding was that nMPs could enter into the muscle tissue through the epidermis of the larvae. It could cause damage to muscle tissue, destroy nerve fibers, inhibit acetylcholinase (AchE) activity, and show great adverse effects on larval movement than mMPs. In conclusion, both nMPs and mMPs at higher concentrations can cause damage to fish larvae and nMPs are potentially more hazardous.

Do microplastics affect the zoanthid Zoanthus sociatus?

Microplastics (1 μm-5 mm), a ubiquitous and persistent marine pollutant, pose a severe threat to coral reefs when recently associated with physiological distress and increased diseases on corals. Studies conducted so far have only reported effects on scleractinian species. Knowledge about its effects on other corals (e.g. Order Zoantharia) remains uncovered, and responses at biochemical levels remain poorly documented. This study aimed to assess the potential effects induced by the presence of microplastics (1 and 10 mg L^-1 low-density polyethylene, LDPE MP, or polyvinyl chloride, PVC MP) in the tropical and subtropical cosmopolitan species Zoanthus sociatus (order Zoantharia. Anthozoa: Hexacorallia), at organism level (survival and behaviour), endosymbionts (photosynthetic efficiency) and the cellular level (oxidative stress, detoxification capacity and energy metabolism). In a short-term exposure (96 h), this species was more sensitive to PVC MP. The presence of this polymer at a concentration of 10 mg L^-1 caused a ten-fold higher adhesion to the coral epidermis, increased photosynthetic efficiency, lipid peroxidation, and antioxidant defences; without, however, inducing energetic costs. Although the observed physiological and biochemical effects did not compromise Z. sociatus survival in the short term, it does not rule out potential long-term (cumulative) effects that could endanger this and other physiologically similar species that underlie coral reefs.

Micro- and nanoplastic toxicity on aquatic life: Determining factors

Plastic pollution has become a major environmental concern due to its omnipresence and degradation to smaller particles. The potential toxicological effects of micro- and nanoplastic on biota have been investigated in a growing number of exposure studies. We have performed a comprehensive review of the main determining factors for plastic particle toxicity in the relevant exposure systems, from publications until including the year 2018. For a focused scope, effects of additives or other pollutants accumulated by the plastic particles are not included. In summary, current literature suggests that plastic particle toxicity depends on concentration, particle size, exposure time, particle condition, shape and polymer type. Furthermore, contaminant background, food availability, species, developmental stage and sex have major influence on the outcome of plastic particles exposures. Frequently reported effects were on body and population growth, energy metabolism, feeding, movement activity, physiological stress, oxidative stress, inflammation, the immune system, hormonal regulation, aberrant development, cell death, general toxicity and altered lipid metabolism. Several times reported were increased growth and food consumption, neuro-, liver- or kidney pathology and intestinal damage. Photosynthesis disruption was reported in studies investigating effects on phytoplankton. For the currently unquantified plastic particles below 10 μm, more toxic effects were reported in all aquatic life, as compared to plastic particles of larger size.

Oxidative stress-related effects induced by micronized polyethylene terephthalate microparticles in the Manila clam

Microplastic (MP) contamination represents a serious threat for marine organisms. Several lab studies demonstrated adverse effects induced by exposure to different MP polymers toward diverse marine species. However, the information regarding toxicity of polyethylene terephthalate (PET) MPs is largely unknown. The present study was aimed at investigating the adverse effects induced by 7-day exposure to two concentrations (0.125 or 12.5 µg/ml) micronized, irregular shaped and variable size PET microparticles (PET-MPs) toward Manila clam (Ruditapes philippinarum). Histological analyses were performed to assess tissue damage on digestive glands, gonads, gut and gills, whereas oxidative stress-related effects, including the concentration of pro-oxidant molecules, activity of antioxidant (superoxide dismutase - SOD, catalase - CAT and glutathione peroxidase - GPx) and detoxifying (glutathione S-transferase - GST) enzymes, as well as levels of lipid peroxidation, were determined in gills and digestive gland. Our results showed that clams ingest and egest micronized PET-MPs, but no marked histological alterations to bivalve tissues occurred. Although PET-MPs did not produce oxidative stress in the digestive gland, these materials significantly altered oxidative status of gills, leading to lipid peroxidation. No apparent clear indication of a weakness of bivalve health status was obtained in this study.

Focus topics on microplastics in soil: Analytical methods, occurrence, transport, and ecological risks

Microplastics with extremely high abundances are universally detected in marine and terrestrial systems. Microplastic pollution in the aquatic environment, especially in ocean, has become a hot topic and raised global attention. However, microplastics in soils has been largely overlooked. In this paper, the analytical methods, occurrence, transport, and potential ecological risks of microplastics in soil environments have been reviewed. Although several analytical methods have been established, a universal, efficient, faster, and low-cost analytical method is still not available. The absence of a suitable analytical method is one of the biggest obstacles to study microplastics in soils. Current data on abundance and distribution of microplastics in soils are still limited, and results obtained from different studies differ significantly. Once entering into surface soil, microplastics can migrate to deep soil through different processes, e.g. leaching, bioturbation, and farming activities. Presence of microplastics with high abundance in soils can alter fundamental properties of soils. But current conclusions on microplastics on soil organisms are still conflicting. Overall, research on microplastics pollution in soils is still in its infancy and there are gaps in the knowledge of microplastics pollution in soil environments. Many questions such as pollution level, ecological risks, transport behaviors and the control mechanisms are still unclear, which needs further systematical study.

Maternal exposure to different sizes of polystyrene microplastics during gestation causes metabolic disorders in their offspring

Microplastics (MPs) are highly concerned environmental pollutants that are ubiquitous in the environmental and might affect human and animal health. In this study, we exposed pregnant mice to 0.5 and 5 μm with 100 and 1000 μg/L polystyrene MPs, then investigated maternal MPs exposure during gestation and evaluated the potential effects on the mice offspring (PND42). In the F1 offspring, the serum triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels and hepatic TC, TG levels were altered, while some of them were only significant in 5 μm MPs-treated group. Various serum metabolites including amino acids and acyl-carnitines were carried out by nonderivatized tandem mass spectrometry, there were 11 and 15 kinds of metabolites changes significantly in 0.5 and 5 μm MPs-treated groups, respectively. Furthermore, the changes of C0 and C0/(C16 + 18) indicators suggested the potential risk of fatty acid metabolism disorder, which was verified by hepatic genes expression. These results indicated that maternal exposure of two different sizes of polystyrene MPs increased risks of metabolic disorder in their offspring, and greater effects were observed in 5 μm MPs-treated groups. The data provides a preliminary exploration of the potential relationship between MPs and the risk metabolic disorder even in the next generation, which might offer new insights into the health risk assessment of MPs.

Adsorption behavior of organic pollutants and metals on micro/nanoplastics in the aquatic environment

Plastic debris becomes currently a ubiquitous environmental pollutant and is susceptible to contamination by many other pollutants, including aqueous metals and organic matter. This review summarizes the effects of environmental factors on the properties and sorption behavior of microplastics, presents a further discussion on the fate of microplastics adsorption on contaminants, and critically discusses the mechanism of sorption behaviors between micro/nanoplastics and normal contaminants. Previous references indicated that the hydrophobicity and particle sizes of microplastics were the dominant influence factors for virgin plastic debris adsorption, whereas for aged microplastics, hydrogen bonding, hydrophilicity and increasing specific surface ratio affected the adsorption behavior. The effects of pH and salinity always influence the sorption conditions by changing the charge state of microplastics and contaminants and causing competing adsorption. In addition, the existence of microplastics affects biotoxicity, increases the dissolved organic matter in the environment, and influences carbon cycling. The knowledge is fundamental to the assessment of potential risks posed by microplastics to organisms from human beings to the entire environment.

Microplastic Contamination Has Limited Effects on Coral Fertilisation and Larvae

Microplastics are ubiquitous throughout the world’s oceans and contaminate coral reef ecosystems. There is evidence of microplastic ingestion by corals and passive contact with coral tissues, causing adverse health effects that include energy expenditure for particle removal from the tissue surface, as well as reduced growth, tissue bleaching, and necrosis. Here, it was examined whether microplastic contamination impairs the success of gamete fertilisation, embryo development and larval settlement of the reef-building coral Acropora tenuis. Coral gametes and larvae were exposed to fifteen microplastic treatments using two types of plastic: (1) weathered polypropylene particles and (2) spherical polyethylene microbeads. The treatments ranged from five to 50 polypropylene pieces L−1 and 25 to 200 microbeads L−1. Fertilisation was only negatively affected by the largest weathered microplastics (2 mm2), but the effects were not dose dependent. Embryo development and larval settlement were not significantly impacted by either microplastic type. The study shows that moderate–high levels of marine microplastic contamination, specifically particles <2 mm2, will not substantially interfere with the success of critical early life coral processes.

Impacts of microplastics on growth and health of hermatypic corals are species-specific

Coral reefs are increasingly affected by the consequences of global change such as increasing temperatures or pollution. Lately, microplastics (i.e., fragments < 5 mm) have been identified as another potential threat. While previous studies have assessed short-term effects caused by high concentrations of microplastics, nothing is known about the long-term effects of microplastics under realistic concentrations. Therefore, a microcosm study was conducted and corals of the genera Acropora, Pocillopora, Porites, and Heliopora were exposed to microplastics in a concentration of 200 particles L^-1, relating to predicted pollution levels. Coral growth and health, as well as symbiont properties were studied over a period of six months. The exposure caused species-specific effects on coral growth and photosynthetic performance. Signs of compromised health were observed for Acropora and Pocillopora, those taxa that frequently interact with the particles. The results indicate elevated energy demands in the affected species, likely due to physical contact of the corals to the microplastics. The study shows that microplastic pollution can have negative impacts on hermatypic corals. These effects might amplify corals' susceptibility to other stressors, further contributing to community shifts in coral reef assemblages.

Microplastics in the environment: A critical review of current understanding and identification of future research needs

Microplastics (plastic particles <5 mm) are a contaminant of increasing ecotoxicological concern in aquatic environments, as well as for human health. Although microplastic pollution is widespread across the land, water, and air, these environments are commonly considered independently; however, in reality are closely linked. This study aims to review the scientific literature related microplastic research in different environmental compartments and to identify the research gaps for the assessment of future research priorities. Over 200 papers involving microplastic pollution, published between 2006 and 2018, are identified in the Web of Science database. The original research articles in 'Environmental Sciences', 'Marine/Freshwater Biology', 'Toxicology', 'Multidisciplinary Sciences', 'Environmental Studies', 'Oceanography', 'Limnology' and 'Ecology' categories of Web of Science are selected to investigate microplastic research in seas, estuaries, rivers, lakes, soil and atmosphere. The papers identified for seas, estuaries, rivers and lakes are further classified according to (i) occurrence and characterization (ii) uptake by and effects in organisms, and (iii) fate and transport issues. The results reveal that whilst marine microplastics have received substantial scientific research, the extent of microplastic pollution in continental environments, such as rivers, lakes, soil and air, and environmental interactions, remains poorly understood.

Polystyrene microplastics ingestion induced behavioral effects to the cladoceran Daphnia magna

Microplastic (μPs) contamination represents a dramatic environmental problem threatening both aquatic and terrestrial organisms. Although several studies have highlighted the presence of μPs in aquatic environments, the information regarding their toxicity towards organisms is still scant. Moreover, most of the ecotoxicological studies of μPs have focused on marine organisms, largely neglecting the effects on freshwater species. The present study aimed at exploring the effects caused by 21-days exposure to three concentrations (0.125, 1.25 and 12.5 μg/mL) of two differently sized polystyrene microplastics (PμPs; 1 and 10 μm) to the Cladoceran Daphnia magna. The ingestion/egestion capability of daphnids (<24 h) and adults, the changes in individual growth and behavior, in terms of changes in swimming activity, phototactic behavior and reproduction, were investigated. Both particles filled the digestive tract of daphnids and adults within 24 h of exposure at all the tested concentrations. Ingested PμPs remained in the digestive tract even after 96 h in a clean medium. For both particles, an overall increase in body size of adults was noted at the end of the exposure to the highest tested concentrations, accompanied by a significant increase in swimming activity, in terms of distance moved and swimming velocity, and by an alteration of the phototactic behavior. A significant increase in the mean number of offspring after the exposure to the highest PμPs concentrations of different size was recorded. Polystyrene μPs can affect behavioral traits of D. magna leading to potentially harmful consequences on population dynamics of this zooplanktonic species.

Microplastic accumulation and biomagnification in a coastal marine reserve situated in a sparsely populated area

Toxic chemicals within and adsorbed to microplastics (0.05-5 mm) have the potential to biomagnify in food webs. However, microplastic concentrations in highly productive, coastal habitats are not well understood. Therefore, we quantified the presence of microplastics in a benthic community and surrounding environment of a remote marine reserve on the open coast of California, USA. Concentrations of microplastic particles in seawater were 36.59 plastics/L and in sediments were 0.227 ± 0.135 plastics/g. Densities of microplastics on the surfaces of two morphologically distinct species of macroalgae were 2.34 ± 2.19 plastics/g (Pelvetiopsis limitata) and 8.65 ± 6.44 plastics/g (Endocladia muricata). Densities were highest in the herbivorous snail, Tegula funebralis, at 9.91 ± 6.31 plastics/g, potentially due to bioaccumulation. This study highlights the need for further investigations of the prevalence and potential harm of microplastics in benthic communities at remote locations as well as human population centers.

Impact of nano-sized plastic on the nutritional value and gut microbiota of whiteleg shrimp Litopenaeus vannamei via dietary exposure

Contamination of the world's oceans with plastic waste has attracted increasing attention in recent years. Whereas the ecological consequences of plastic pollution have been the focus of increasing research, the health-related implications of plastic pollution have been somewhat overlooked. In this study, we exposed whiteleg shrimp (Litopenaeus vannamei), a widely consumed marine species, to nano-sized plastic (polystyrene) via a simulated marine food chain in which mussel (Mytilus edulis) was the food source, and evaluated the effects of plastic contamination on shrimp physical, biochemical, and nutritional characteristics over a 21-day exposure period. We identified the changes in certain important biochemical and nutritional indicators, including changes in the gut microbiota and contents of amino acids and fatty acids. The biochemical analysis revealed that microbial activities in the intestine and the glutathione S-transferase and superoxide dismutase activities changed in L. vannamei exposed to nano-sized plastic. In these individuals, the levels of some essential amino acids and fatty acids also decreased. Overall, our findings indicate that plastic pollution can directly interfere with nutritional changes in marine food resources, thereby indirectly causing potential health implications for human consumers.

Ingestion, egestion and post-exposure effects of polystyrene microspheres on marine medaka (Oryzias melastigma)

Microplastics (MPs) are of environmental concern due to their bioavailability and potential impacts on a wide range of marine biota. In this study, we investigated the ingestion, bioaccumulation and egestion of fluorescent polystyrene (PS) micospheres (10 μm) in both larvae and adults of marine medaka (Oryzias melastigma), with or without food supply. The post-exposure effects of non-fluorescent PS (10 μm) on the survival, growth and reproduction of medaka larvae were also explored. Results showed that the PS microspheres could be ingested by both larvae and adults during the 48 h-exposure. Notably, feeding status was found to significantly affect the ingestion in medaka adults, which was not observed in the larvae. The egestion process of PS was rapid during the first recovery day but there was still certain percent of particles retained in digestive tracts at the end of 7 d recovery for either larvae or adults. After a 14 d pre-exposure with the non-fluorescent PS microspheres, the subsequent survival, growth and reproduction of medaka larvae were all significantly affected at the end of 120 d of experiment without PS. Overall, these results indicate that fishes might ingest or retain more MPs if the environmental abundance of MPs continues to increase while the available food decreases. Medaka fishes in larval stage have no capacity to select natural food sources like the adults. The chronic and "legacy effect" of MPs might also be a problem worthy paid more attention in future research instead of acute and immediate effect studies.

Interaction between microplastics and microorganism as well as gut microbiota: A consideration on environmental animal and human health

Microplastics (MPs) has gradually become a global environmental pollution problem and may harm human and animal health. In recent years, a large number of studies had shown that MPs had various toxicological effects on different organisms. At the same time, a number of studies had also shown that gut microbiota was closely related to host health and as a toxicity target for certain environmental pollutants including MPs. The fact is that more and more studies proved that MPs not only could interact with microorganism directly but also serve as a carrier for other pollutants and interacted with microorganism indirectly. In this review, we summarized the interactions between MPs and microorganisms as well as gut microbiota, and considered the possible impacts of MPs on environmental animal and human health, suggesting that the environmental microorganisms and the gut microbiota of animals were also the very important target for MPs. We hope that more studies pay more attention to focus on the relationship between MPs, gut microbiota, and environmental animals and human health in the future.

Microplastics and the gut microbiome: How chronically exposed species may suffer from gut dysbiosis

As small pieces of plastics known as microplastics pollute even the remotest parts of Earth, research currently focuses on unveiling how this pollution may affect biota. Despite increasing awareness, one potentially major consequence of chronic exposure to microplastics has been largely neglected: the impact of the disruption of the symbiosis between host and the natural community and abundance pattern of the gut microbiota. This so-called dysbiosis might be caused by the consumption of microplastics, associated mechanical disruption within the gastrointestinal tract, the ingestion of foreign and potentially pathogenic bacteria, as well as chemicals, which make-up or adhere to microplastics. Dysbiosis may interfere with the host immune system and trigger the onset of (chronic) diseases, promote pathogenic infections, and alter the gene capacity and expression of gut microbiota. We summarize how chronically exposed species may suffer from microplastics-induced gut dysbiosis, deteriorating host health, and highlight corresponding future directions of research.