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Microplastics are emerging pollutants of global concern, and their presence in the aquatic environment poses a serious risk for aquatic biota. While many studies have been conducted on the presence of microplastics in marine habitats, little research has been done in freshwater African reservoirs on microplastic pollution and their impacts on fish within the subtropical regions. To bridge this gap, the current study investigated microplastic abundances and distribution in freshwater fish within Nandoni reservoir, South Africa, across two seasons (i.e., hot–wet, cool–dry). Fish were randomly sampled using seine and gill nets from seven sites within the reservoir. In the laboratory, fish were then sorted according to taxa before dissecting them to remove the gills and the gastrointestinal tract (GIT). The organs were digested using hot hydrochloric acid and hydrogen peroxide, and the microplastics were classified according to their colours and shapes. Among the 94 fishes (i.e., 8 species) examined, microplastics were detected in 86.6% of the eight species caught. Microplastics were dominant in the gills and GIT during the cool–dry and hot–wet seasons, respectively. High microplastic abundances were found in the gills of Micropterus salmoides and the GIT of Coptodon rendalli, where fibres and the transparent colour were the most dominant. The results further showed high microplastic abundances in benthopelagic feeders highlighting that habitat influences fish consumption of microplastics whether directly or indirectly. Significant differences were observed in the feeding zone and season for all microplastic types. Microplastic sources in the reservoirs could be due to anthropogenic activities such as illegal dumping, fishing, and agriculture. Thus, there is a need for further investigation into the relation of fish weight, fish sex and body in relation to microplastic pollution. The highlighted ecological factors should be taken into consideration for future research and management actions aimed at mitigating and protecting the negative impacts of microplastic pollution on environmental and human health. [ABSTRACT FROM AUTHOR]

Abstract Microplastics are emerging pollutants of global concern, and their presence in the aquatic environment poses a serious risk for aquatic biota. While many studies have been conducted on the presence of microplastics in marine habitats, little research has been done in freshwater African reservoirs on microplastic pollution and their impacts on fish within the subtropical regions. To bridge this gap, the current study investigated microplastic abundances and distribution in freshwater fish within Nandoni reservoir, South Africa, across two seasons (i.e., hot–wet, cool–dry). Fish were randomly sampled using seine and gill nets from seven sites within the reservoir. In the laboratory, fish were then sorted according to taxa before dissecting them to remove the gills and the gastrointestinal tract (GIT). The organs were digested using hot hydrochloric acid and hydrogen peroxide, and the microplastics were classified according to their colours and shapes. Among the 94 fishes (i.e., 8 species) examined, microplastics were detected in 86.6% of the eight species caught. Microplastics were dominant in the gills and GIT during the cool–dry and hot–wet seasons, respectively. High microplastic abundances were found in the gills of Micropterus salmoides and the GIT of Coptodon rendalli, where fibres and the transparent colour were the most dominant. The results further showed high microplastic abundances in benthopelagic feeders highlighting that habitat influences fish consumption of microplastics whether directly or indirectly. Significant differences were observed in the feeding zone and season for all microplastic types. Microplastic sources in the reservoirs could be due to anthropogenic activities such as illegal dumping, fishing, and agriculture. Thus, there is a need for further investigation into the relation of fish weight, fish sex and body in relation to microplastic pollution. The highlighted ecological factors should be taken into consideration for future research and management actions aimed at mitigating and protecting the negative impacts of microplastic pollution on environmental and human health.

Microplastic (<5 mm) pollution has been documented globally throughout freshwater and marine ecosystems. Exposure to and ingestion of microplastics presents a threat to the health of aquatic and marine organisms and humans through the consumption of fish and crustaceans. Understanding the factors which influence microplastic ingestion by fish is a key step in predicting the potential health risks. Drivers of microplastic consumption have been studied in lab settings, but there has been limited ability to confirm in field studies. Here we examine the roles and contributions of feeding guild, pelagic microplastic concentrations, and fish length to microplastic consumption by three species of fish across four lake ecosystems in Minnesota, United States. Fish samples were collected in the summers of 2019 and 2020 and processed to determine variability in microplastic ingestion. Identifying particles between 0.18 and 5 mm, plastic ingestion ranged from 0.6 microplastics fish-1 in Elk Lake (low surface water microplastics) bluegill to 1.09 microplastics fish-1 in White Iron Lake (moderate surface water microplastics) cisco. Results indicate that microplastic consumption by filter feeding cisco is driven by surface water microplastic concentrations, while microplastic consumption by visual feeding bluegill and yellow perch is not. Additionally, the high variability of ingestion between lake ecosystems coupled with the complex behavior of some fish species presents difficulties in identifying primary drivers of microplastic consumption that would be broadly applicable across ecosystems and species. [ABSTRACT FROM AUTHOR]

Microplastics can be ingested by a wide range of aquatic animals. Extensive studies have demonstrated that microplastic ingestion—albeit often not lethal—can affect a range of species life‐history traits. However, it remains unclear how the sublethal effects of microplastics on individual levels scale up to influence ecosystem‐level dynamics through cascading trophic interactions.Here we employ a well‐studied, empirically fed three‐species trophic chain model, which was parameterized to mimic a common type of aquatic ecosystems to examine how microplastic ingestion by fish on an intermediate trophic level can produce cascading effects on the species at both upper and lower trophic levels.We show that gradually increasing microplastics in the ingested substances of planktivorous fish may cause population structure effects such as skewed size distributions (i.e. reduced average body length vs. increased maximal body size), and induce abrupt declines in fish biomass and reproduction.Our model analysis demonstrates that these abrupt changes correspond to an ecosystem‐level tipping point, crossing which difficult‐to‐reverse ecosystem degradation can happen. Importantly, microplastic pollution may interact with other anthropogenic stressors to reduce safe operating space of aquatic ecosystems.Our work contributes to better understanding complex effects of microplastic pollution and anticipating tipping points of aquatic ecosystems in a changing world. It also calls attention to an emerging threat that novel microplastic contaminants may lead to unexpected and abrupt degradation of aquatic ecosystems, and invites systematic studies on the ecosystem‐level consequences of microplastic exposure. [ABSTRACT FROM AUTHOR]

The present study investigates the potential effects and risks of polyethylene microbeads (PEMBs) and PEMBs associated with PCB-153 (PEMB-PCB) on Daphnia magna using a chronic exposure study approach. Daphnia magna were exposed to PEMBs, PCB-153, and PEMB-PCB for 21 days. Accumulation of PEMBs and PCB-153 in D. magna and effects on survival and reproduction of the organisms were measured. Overall, D. magna ingested and accumulated PEMBs and PCB-153. The accumulation of PEMBs increased with exposure time and was higher for PEMB exposure than for PEMB-PCB exposure. However, PCB-153 accumulation did not appear to increase over time. Exposure to PCB-153 in water resulted in higher PCB-153 accumulation than did PEMB-PCB exposure. Polyethylene microbeads and PCB-153 appeared to interact, resulting in a lower accumulation of PEMBs and PCB-153 and causing less effect on reproduction of D. magna. Survival of D. magna was affected by PEMBs, PCB-153, and PEMB-PCB. Results of the present study reveal potential risks of MPs to living organisms and ecosystems, especially when considering long-term exposure, which is relevant for microplastic pollution because of the persistence and continuous increase in MP abundance in the environment. More research should be conducted to understand the interactive effect mechanisms of MP and pollutant mixture exposure on organisms that would help explain the decreased accumulation of pollutants in organisms when MPs are present. [ABSTRACT FROM AUTHOR]

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Microplastics (MPs) are emerging pollutants that are ubiquitous in the environment, and may be a potential threat to human health. This review describes the MP exposure sources and pathways through drinking water, food intake, and air inhalation. The unregulated discharge of MPs in water sources and the absence of required MP filter technology in water treatment plants are important routes of MP exposure through drinking water. The presence of MPs in food may lead to the accumulation of MPs in the body. Exposure to MPs can occur through airborne fallout and dust inhalation in both indoor and outdoor environments. This review summarizes the MP exposure sources and possible pathways in the human body, and illustrates that the intake of drinking water, food consumption, and air inhalation should be assessed in during routine activities. Integr Environ Assess Manag 2023;19:1422–1432. © 2023 SETAC Key Points: •Three pathways through which humans ingest microplastics are drinking water, food intake, and air inhalation.•Pollution of water sources and nonexistence of MP filter technology in water treatment plants are important routes of MP exposure through drinking water.•Food pollution and cooking processes may lead to the accumulation of MPs in the body.•MP exposure can occur through airborne fallout and dust inhalation in both indoor and outdoor environments. [ABSTRACT FROM AUTHOR]

Following global trends, research to determine the presence and abundance of microplastics (MPs) in environmental matrices in Colombia has focused on the coastal and marine environments. However, little scientific information is available on the impact of this pollutant on wetlands and fish. In this study, we provided scientific data on the occurrence and abundance of MPs in water and fish from Tocagua Lake, an important wetland in the Colombian Caribbean, and the unique habitat of wild cotton-top tamarins (Saguinus oedipus). Water (72) and fish (228 individuals of six species) samples were collected during four sampling events and two climatic seasons (wet and dry). A total of 1174 microplastic particles were collected in water with an average abundance of microplastics at the six stations sampled during four sampling events of 0.96 ± 0.40 MPs/L, and 648 MPs were identified in the gastrointestinal tract of 191 individuals, corresponding to a frequency of occurrence of 83.7%. Black- and blue-colored fiber MPs were particles that predominated in both matrices (water and fish), and seven types of polymers were identified through attenuated total reflectance Fourier transform infrared spectroscopy analysis. The abundance, type, and color of MPs in water and fish were not significantly different between seasons. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are increasingly being studied because they have become ubiquitous in aquatic and terrestrial environments. However, little is known about the negative effects of co-contamination by polypropylene microplastic (PP MPs) and heavy metal mixtures on terrestrial environment and biota. This study assessed the adverse effects of co-exposure to PP MPs and heavy metal mixture (Cu2+, Cr6+, and Zn2+) on soil quality and the earthworm Eisenia fetida. Soil samples were collected in the Dong Cao catchment, near Hanoi, Vietnam, and analyzed for changes in extracellular enzyme activity and carbon, nitrogen, and phosphorus availability in the soil. We determined the survival rate of earthworms Eisenia fetida that had ingested MPs and two doses of heavy metals (the environmental level — 1 × — and its double — 2 ×). Earthworm ingestion rates were not significantly impacted by the exposure conditions, but the mortality rate for the 2 × exposure conditions was 100%. Metal-associated PP MPs stimulated the activities of β-glucosidase, β-N-acetyl glucosaminidase, and phosphatase enzymes in soil. Principle component analysis showed that these enzymes were positively correlated with Cu2+ and Cr6+ concentrations, but negatively correlated with microbial activity. Zn2+ showed no correlation with soil extracellular enzyme activity or soil microbial activity. Our results showed that co-exposure of earthworms to MPs and heavy metals had no impact on soil nitrogen and phosphorus but caused a decrease in total soil carbon content, with a possible associated risk of increased CO2 emissions. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are widespread pollutants of emerging concern, and the risks associated with their ingestion have been reported in many organisms. Terrestrial environments can be contaminated with MPs, and terrestrial organisms, including arthropods, are predisposed to the risk of ingesting MPs. In the current study, the larvae of the paper wasp Polistes satan were fed two different doses (6 mg or 16 mg at once) of polystyrene MPs (1.43 mm maximum length), and the effects of these treatments on immature development and survival till adult emergence were studied. Ingestion of the two doses resulted in mortality due to impaired defecation prior to pupation. The survival of larvae that ingested 16 mg of MPs was significantly lower than that of the control. The ingestion of 16 mg of MPs also reduced the adult emergence (11.4%) in comparison to the control (44.4%). MPs were not transferred from the larvae to the adults that survived. These findings demonstrate that MP ingestion can be detrimental to P. satan, e.g. larval mortality can decrease colony productivity and thus the worker force, and that MPs can potentially affect natural enemies that occur in crops, such as predatory social wasps. [ABSTRACT FROM AUTHOR]

Microplastics are contaminants of emerging concern, not least due to their global presence in marine surface waters. Unsurprisingly, microplastics have been reported in salts harvested from numerous locations. We extracted microplastics from 13 European sea salts through 30% H2O2 digestion and filtration over 5-µm filters. Filters were visually inspected at magnifications to x100. A subsample of potential microplastics was subjected to Raman spectroscopy. Particle mass was estimated, and human dose exposure calculated. After blank corrections, median concentrations were 466 ± 152 microplastics kg-1 ranging from 74 to 1155 items kg-1. Traditionally harvested salts contained fewer microplastics than most industrially harvested ones (t-test, p

This study analyzed microplastics in the gastrointestinal tract of Siberian dace (Leuciscus leuciscus subsp. baicalensis (Dybowski, 1874)) in the remote Yenisei tributary of the Nizhnyaya (Lower) Tunguska River (Siberia, Russia). µRaman analysis showed that 60% of the fish from two different sites had ingested plastic microparticles (on average, 1.55 ± 1.95 items per individual). The most common type of microplastic were fibers, and the most abundant size category was 300 to 1000 µm. In the studied population, no significant differences in the MP content between the two sites or between males and females were found (p > 0.05). The tendency for higher MP ingestion by Siberian dace at earlier ages (2+ and 3+) compared to later (4+ and 5+) was observed, which may be connected to the features of the fish biology and ecology. [ABSTRACT FROM AUTHOR]

Microplastics adversely affect organisms through physical damage, inhibition of food assimilation, and/or toxicity of chemical leachates. We investigated the influence of feeding mode on microplastic ingestion by using polystyrene microbeads (diameter: 4.1 and 20.6 μm) and the estuarine benthic amphipod Grandidierella japonica, which can switch between filter-feeding and deposit-feeding modes. When provided with sediment, amphipods burrowed and were in the filter-feeding mode; they ingested 4.1 and 20.6 μm beads in the ratio at which the two sizes were suspended in the water. Without sediment, however, the amphipods were mainly in the deposit-feeding mode and ingested more 20.6 μm beads, which tended to be deposited on the bottom, compared with 4.1 μm beads. In addition, the number of microbeads ingested by the amphipods in sediment increased as the amount of food provided (i.e., fish food TetraMin) increased, whereas no such increase was observed for the amphipods without sediment. These results indicate that the microbead ingestion was dependent on feeding mode (i.e., presence/absence of sediment), amount of food, and distribution of microbeads (i.e., sizes of microbeads). To better understand the ingestion, accumulation, and toxicity of microplastics in aquatic environments, we recommend that more attention be paid to behavioral changes in benthic organisms.

Microplastic pollution in marine ecosystems has become a significant, global concern which attracting the attention of academics and policy makers. This study provides information regarding the microplastic occurrence in the gill and gastrointestinal tract (GIT) of Chelon ramada (Risso, 1827). A total of 158 MPs were extracted from the gill and GIT with a mean of 1.9±1.8 particle/individual in gill and 3.4±2.1 particle/individual in GIT. Fiber was the most commonly extracted microplastic type (79%), followed by fragments (16%), film (4%) and pellet (2%). Mean size of extracted MPs from the organs of Chelon ramada was found as 1251±1602 µm. Black, transparent, red and blue MPs were extracted from the organs and dominance of black and transparent MPs were observed in the gill and GIT, respectively. This study is providing the first data regarding the microplastic ingestion of Chelon ramada and the results obtained in this will help to understand the relationship between anthropogenic influences and microplastic ingestion. [ABSTRACT FROM AUTHOR]

Following global trends, research to determine the presence and abundance of microplastics (MPs) in environmental matrices in Colombia has focused on the coastal and marine environments. However, little scientific information is available on the impact of this pollutant on wetlands and fish. In this study, we provided scientific data on the occurrence and abundance of MPs in water and fish from Tocagua Lake, an important wetland in the Colombian Caribbean, and the unique habitat of wild cotton-top tamarins (Saguinus oedipus). Water (72) and fish (228 individuals of six species) samples were collected during four sampling events and two climatic seasons (wet and dry). A total of 1174 microplastic particles were collected in water with an average abundance of microplastics at the six stations sampled during four sampling events of 0.96 ± 0.40 MPs/L, and 648 MPs were identified in the gastrointestinal tract of 191 individuals, corresponding to a frequency of occurrence of 83.7%. Black- and blue-colored fiber MPs were particles that predominated in both matrices (water and fish), and seven types of polymers were identified through attenuated total reflectance Fourier transform infrared spectroscopy analysis. The abundance, type, and color of MPs in water and fish were not significantly different between seasons.

Recent advances in genetic manipulation such as triploid breeding and artificial selection, have rapidly emerged as valuable hatchery methodologies for enhancing seafood stocks. The Pacific oyster Magallana gigas is a leading aquaculture species worldwide and key ecosystem engineer that has received particular attention in this field of science. In light of the growing recognition of the ecological effects of intraspecific variation, oyster polyploids provide a valuable opportunity to assess whether intraspecific diversity affects physiological responses to environmental stressors. While the responses of diploid and triploid oysters to climate change have been extensively investigated, research on their sensitivity to environmental pollution remains scarce. Here, we assess whether genotypic (i.e., ploidy) variation within Magallana gigas affects physiological responses to microplastic pollution. We show that diploid and triploid M. gigas have similar clearance rates and ingest similar amounts of microplastics under laboratory-controlled condition. In addition, they exhibited similar heart rates after prolonged exposure to microplastic leachates. Our findings suggest that intraspecific variations within M. gigas ploidy does not affect oyster responses to microplastic pollution. However, regardless of ploidy, our work highlights significant adverse effects of microplastic leachates on the heart rate of M. gigas and provides evidence of microplastic ingestion in the laboratory. [Display omitted] • We tested whether ploidy affects oyster responses to microplastic pollution. • We focused on diploid and triploid juvenile oyster, Magallana gigas. • Diploid and triploid ingested similar amount of polyester microfibre. • Diploid and triploid heart rate was similar but decreased after leachates exposure. • Oyster ploidy did not affect physiological responses to microplastic pollution. [ABSTRACT FROM AUTHOR]

Over the past decade, concerns over microplastic pollution in the marine ecosystem has increasingly gained more attention, but research investigating the ingestion of microplastics by marine fish in Malaysia is still regrettably lacking. This study investigated the microplastic presence, abundance, and morphological types within the guts of four species of commercial marine fish (Atule mate, Crenimugil seheli, Sardinella fimbriata and Rastrelliger brachysoma) caught in seawater off the coast of Malaysia’s Northwest Peninsular. A total of 72 individual commercial marine fish guts from four species (fish per species n = 18) were examined. Remarkably, this study found that 100% of the samples contained microplastics. A total number of 432 microplastics (size < 5 mm) from the four species were found in the excised marine fish guts. The most common type of microplastic discovered was fragment, which accounted for 49.5% of all microplastics present. The gut microplastic content differed between species. Sardinella fimbriata recorded the greatest amount of microplastic ingestion, with an average microplastic count of 6.5 (±4.3) items per individual fish. However, there were no statistically significant differences found when comparing study species and different locations. SEM-EDX analysis confirmed the presence of microplastic particles by identifying the chemical elements found in the samples. Since the four studied species of commercial marine fish are popular protein sources in Malaysians’ daily diet, this study suggests potential microplastic exposure to humans via contaminated fish consumption in Malaysia, which was previously unknown. Based on previous scientific evidence, this study also demonstrates the high probability of microplastic ingestion in marine fish in the Malaysian seawater, which could have an adverse effect on fish health as well as marine biota.

Mussels are a group of bivalves that includes the dominant species of shallow-sea, freshwater, and deep-sea chemosynthetic ecosystems. Mussels cling to various solid underwater surfaces using a proteinaceous thread, called the byssus, which is central to their ecology, physiology, and evolution. Mussels cluster using their byssi to form "mussel beds," thereby increasing their biomass per unit of habitat area, and also creating habitats for other organisms. Clustered mussels actively filter feed to obtain nutrients, but also ingest pollutants and suspended particles; thus, mussels are good subjects for pollution analyses, especially for microplastic pollution. The byssus also facilitates invasiveness, allowing mussels to hitchhike on ships, and to utilize other man-made structures, including quay walls and power plant inlets, which are less attractive to native species. Physiologically, mussels have adapted to environmental stressors associated with a sessile lifestyle. Osmotic adaptation is especially important for life in intertidal zones, and taurine is a major component of that adaptation. Taurine accumulation systems have also been modified to adapt to sulfide-rich environments near deep-sea hydrothermal vents. The byssus may have also enabled access to vent environments, allowing mussels to attach to "evolutionary stepping stones" and also to vent chimneys. [ABSTRACT FROM AUTHOR]

This study analyzed microplastics in the gastrointestinal tract of Siberian dace (Leuciscus leuciscus subsp. baicalensis (Dybowski, 1874)) in the remote Yenisei tributary of the Nizhnyaya (Lower) Tunguska River (Siberia, Russia). µRaman analysis showed that 60% of the fish from two different sites had ingested plastic microparticles (on average, 1.55 ± 1.95 items per individual). The most common type of microplastic were fibers, and the most abundant size category was 300 to 1000 µm. In the studied population, no significant differences in the MP content between the two sites or between males and females were found (p > 0.05). The tendency for higher MP ingestion by Siberian dace at earlier ages (2+ and 3+) compared to later (4+ and 5+) was observed, which may be connected to the features of the fish biology and ecology.

Plastic pollution has spread through all parts of the marine environment, representing a significant threat to species and ecosystems. This study investigates the role of copepods as widespread microplastic reservoirs in the marine environment, by performing, a systematic review, meta-analysis, and semiquantitative analysis of scientific articles focusing on the interaction between copepods and microplastics under field conditions. Our findings indicate that despite uniformly low ingestion of microplastics across different marine layers and geographical areas, with a slight uptake in neustonic copepods, copepods might constitute one of the largest marine microplastic reservoirs. This phenomenon is attributed more to their vast abundance than to average microplastic ingestion values. In this article, a framework for data analysis and reporting is proposed to facilitate future large-scale evaluations and modelling of their extent and impact on plastic and carbon cycles. These insights place copepods at the forefront of the marine plastic cycle, possibly affecting plastic distribution, and bioavailability, thereby opening new pathways for understanding the complex dynamics of microplastics in marine ecosystems. [Display omitted] • Copepods show low MPs ingestion (0–0.82 MPs/individual) under field conditions. • Sample size <50 individuals is inadequate for estimating MPs retention in copepods. • High MPs retention in copepods, up to 2700 MP/m³. • MPs retention is related to copepod abundance, not to mean ingestion values. • Copepods can be major microplastic reservoirs in the plastic cycle. [ABSTRACT FROM AUTHOR]

Poisson regression model is used to investigate the relationship among parameters when the response variable is a count data that follows Poisson distribution. The Poisson regression model is widely applied in various fields such as medical and epidemiological study. However, the application of this model in environmental science, particularly microplastic pollution is still limited. Small plastic particles with a size less than 5 mm or also known as microplastics are reported as an emerging pollutant in the aquatic environment. Microplastics have also been recognized as a serious threat to commercial fish through ingestion. Thus, the Poisson regression model was applied to determine factors that are contributed to the microplastic ingestion by African catfish. Three Poisson regression models were separately developed for each factor such as color, morphology, and environments. Based on the models, the significant difference was observed for all microplastic colors and morphology except for bead. Meanwhile, only two variables of water quality factor were significant and affected the number of ingested microplastics. In conclusion, the relationships between ingested microplastics and its factors was successfully represented using Poisson regression model. [ABSTRACT FROM AUTHOR]

Microplastic pollution is now a global issue. Reservoirs are an enclosed aquatic environment at risk from accumulation of microplastics. Few studies have used fish species as bio-indicators to monitor microplastic contamination in reservoirs. Freshwater fish were caught by local fishermen from 10 stations around the Ubolratana Reservoir, Thailand in October 2018 and the abundance, size, color and shape of microplastic particles in their stomachs and intestines were investigated. Fourteen fish species were examined. Results showed that 96.4% of the fish had ingested microplastics at mean abundance of 2.921.30 particles per fish, with significant differences of abundance between species. Microplastic abundance was highest in carnivorous fish Parambassis siamensis (4.111.08 particles per fish). The most common size of ingested microplastics was over 0.5 mm (66.4%), with 51.0% as blue color and 98.2% fiber shaped. High levels of microplastics were ingested by fish located in the middle and lower parts of the reservoir. Results revealed that blue fiber microplastics dominantly observed in fish were derived from the breakdown of nets used for fishing activities. [ABSTRACT FROM AUTHOR]

Abstract Aim The aim was to analyze the incidence of microplastics in the diet of fish in the middle Uruguay River. Methods The present work analyzed the gastrointestinal content of two species: Astyanax lacustris and Iheringichthys labrosus. Results This study provides the first evidence of synthetic materials, such as fibres and plastics in the gastrointestinal tract of fish species in the Middle Uruguay River basin. A sample of sixty-one A. lacustris and twenty-nine I. labrosus were examined to highlight the ingestion of microplastics in the middle section of the Uruguay River in Brazil. In the A. lacustris, eleven fibres and two fragments were found in their gastrointestinal contents, corresponding to 18.1% of the specimens, while in the I. labrosus, twelve fibres and one fragment were found, corresponding to 34.5% of the specimens analyzed. Blue staining was also prevalent in the occurrence of microplastics. Conclusions These data are the first record of microplastics in this zone and represent a baseline for this contamination for future studies.

Although millions of tons of plastics end up in oceans each year, floating plastics account for only about 1% of all plastic inputs in the ocean. Particularly, microplastics below 1 mm in length, are missing in surface waters due to removal processes like ingestion by marine animals, biofouling, and sinking. Here, we studied how a species of mushroom corals (Danafungia scruposa), common in the Maldives, contributed to the removal of microplastics from the water suspension through active (ingestion) and passive (adhesion to the surface) mechanisms. We evaluated if removal rates were affected by the presence of the coral natural prey (i.e., Artemia salina) and by biofouling on the surface of the microplastic. We found that the coral quickly interacts both actively and passively with microplastics and that the probability for the coral to ingest and retain microplastics was higher when the surface of the microplastic was biofouled. We also found that passive adhesion of microplastics was the primary mechanism through which corals sequester microplastics from the water column.

The ingestion of microplastics by marine species has been at least partially attributed to plastics emitting a dimethyl sulfide signature when exposed to marine conditions. Dimethyl sulfide, a member of the volatile organic sulfur compounds group, is an infochemical that many species rely on to locate and identify prey while foraging. Microplastic ingestion is also observed in freshwater systems; however, this study shows that the same dimethyl sulfide signature is not obtained by three common types of plastic (high-density polyethylene, low-density polyethylene, and polystyrene) in freshwater systems, suggesting that there may be an alternate mechanism driving plastic ingestion by freshwater species. [ABSTRACT FROM AUTHOR]

Abstract Plastic debris has been recognized as a growing threat to marine biota due to its widespread distribution and possible interactions with marine species. Concerns over the effects of plastic polymers in marine ecosystems is reflected in the high number of toxicological studies, regarding microplastics (<5 mm) and marine fauna. Although several studies reported that organisms ingest and subsequently eliminate microplastics (MP), the potential effects at organ and tissue level remain unclear, especially considering exposure to different microplastic sizes and concentrations. The present study aimed at investigating potential pathophysiological effects of the ingestion of MP by marine filter-feeders. For the purpose, Mediterranean mussel (Mytilus galloprovincialis) was exposed to spherical polystyrene MP (2 and 10 μm Ø) over short- and medium-term exposure periods, under single and combined concentrations that represent high, yet realistic doses (10 and 1000 MP mL−1). Overall, results suggest rapid MP' clearance from water column by filtering, regardless of MP size. Ingestion occurred, identified by MP in the lumen of the gut (mostly in midgut region), followed by excretion through faeces. However, no MP were found in gills or digestive gland diverticula. Biochemical indicators for oxidative stress were generally irresponsive regardless of organ and time of exposure. Small foci of haemocytic infiltration in gastric epithelia were found, albeit not clearly related to MP ingestion. Globally, no evident histopathological damage was recorded in whole-body sections of exposed animals. The present findings highlight the adaptative ability of filter-feeding bivalves to cope with filtration of suspended MP, resulting in rapid elimination and reduced internal damage following ingestion of spherical MP. Nevertheless, the fact that the animals are able to translocate MP to the gut reveals that filter feeding organisms may indeed became a target of concern for fragmented materials with smaller, mixed sizes and sharper edges. Graphical abstract Image 1 Highlights • Mussels are able to ingest and excrete polystyrene microplastics. • MP are rapidly processed through the mussels' digestive tract. • No significant pathological effects occurred even during longer-term exposure. • No clear evidence of oxidative stress caused by ingested polystyrene MP. Effects of microplastic ingestion by filter-feeding bivalves. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) content of the digestive tract of two commercial fish from the northern shores of the Oman Sea were investigated. The MPs were characterized by optical microscopy, fluorescent microscopy, and SEM-EDX for their number, shape, size, and color. Polymer composition was analyzes using micro-Raman spectroscopy (RMS). MPs were recovered in all fish samples (100 %), with an average of 43.16 ± 8.23 items/individual in Otolithes ruber , and 29.9 ± 2.73 items/individual in Acanthopagrus latus. The predominant shape of MPs in both fishes was fiber (46 %) with black, transparent, and white colors. The majority of MPs were <1000 μm (75 %), and half of the MPs were smaller than 300 μm in size. Their synthetic nature was confirmed by Nile Red staining and determination of the elemental composition of selected items. Polypropylene (PP) and polyethylene (PE) were the dominant plastic polymers in the fish digestive tracts. This study reveals abundance distribution of MPs in digestive tract of commercial marine fish. High number of ingested MPs can alarm the accumulation of MPs in the northern of Oman Sea ecosystem with anthropogenic activities and raises issues in public health. [Display omitted] • MPs were ingested by 100 % of examined Otolithes ruber and Acanthopagrus latus. • MPs were often fibers (46 %) followed by fragments (40 %), beads and films (<15 %). • Half of the MPs were <300 μm, including all microbeads. • Black, transparent and white MPs were the most predominant in both species (∼90 %). • PP and PE were identified the main polymers by micro-Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Anthropogenic Marine Debris (AMD) in the SE Pacific has primarily local origins from land-based sources, including cities (coastal and inland), beach-goers, aquaculture, and fisheries. The low frequency of AMD colonized by oceanic biota (bryozoans, lepadid barnacles) suggests that most litter items from coastal waters of the Humboldt Current System (HCS) are pulled offshore into the South Pacific Subtropical Gyre (SPSG). The highest densities of floating micro- and macroplastics are reported from the SPSG. An extensive survey of photographic records, unpublished data, conference proceedings, and published studies revealed interactions with plastics for 97 species in the SE Pacific, including 20 species of fish, 5 sea turtles, 53 seabirds, and 19 marine mammals. Sea turtles are most affected by interactions with plastics, underlined by the fact that 4 of the 5 species suffer both from entanglement and ingestion. Reports gathered in this review suggest that interactions along the continental coast are mostly via entanglement. High frequencies of microplastic ingestion have been reported from planktivorous fish and seabirds inhabiting the oceanic waters and islands exposed to high densities of microplastics concentrated by oceanic currents in the SPSG. Our review also suggests that some species from the highly productive HCS face the risk of negative interactions with AMD, because food and plastic litter are concentrated in coastal front systems. In order to improve the conservation of marine vertebrates, especially of sea turtles, urgent measures of plastic reduction are needed.

Abstract Millimetre-sized fragments have been documented in many fish species, but their transfer through food webs is still poorly understood. Here we quantified and described plastic fragments in the digestive tracts of 43 Easter Island flying fish (Cheilopogon rapanouiensis) and 50 yellowfin tunas (Thunnus albacares) from coastal waters around Rapa Nui (Easter Island) in the South Pacific subtropical gyre, and of fish preyed upon by T. albacares. Overall, seven C. rapanouiensis (16%) individuals had ingested microplastics, most of which resembled the common planktonic prey of the fish. One microplastic was found in the gut of a fish ingested by a tuna, which indicates that trophic transfer may occur between tuna and prey. A single T. albacares (2%) had ingested five mesoplastics (15.2–26.3 mm) that were probably not mistaken for prey items, but rather accidentally ingested during foraging on fish prey. The absence of microplastics in T. albacares suggests that such small particles, if transferred from the prey, do not accumulate in the relatively large digestive tract of large predators. On the other hand, larger plastic items may accumulate in the gut of tunas, to which they may induce deleterious effects that still need to be examined. However, only a small portion of the fish had ingested mesoplastics. The results of this study suggest that microplastic contamination is not an immediate threat to large predatory fish, such as T. albacares , along the coast of Easter Island within the South Pacific subtropical gyre. Graphical abstract Image 1 Highlights • Microplastics were found in flying fish and fish preyed upon by yellowfin tunas. • Microplastics may be transferred from the prey, but do not remain in the tunas' guts. • Microplastic contamination might not be an immediate threat to large predatory fish. • Large plastic fragments may accumulate in tunas, but were found in only few (2%) of the fish. Microplastics may be transferred from fish prey to their predators, but do not remain in the predators' guts. Mesoplastics may accumulate in the guts of large predators, but are only ingested by few fish. [ABSTRACT FROM AUTHOR]

Abstract Microplastic ingestion by marine organisms presents an emerging threat to marine ecosystems; microplastics in different marine species are currently reported worldwide. This study aims to assess microplastic ingestion in four, highly commercial, marine species from Greek waters in the Northern Ionian Sea (Mediterranean Sea). Microplastics were found in mussels (Mytilus galloprovincialis) and all three fish species (Sardina pilchardus , Pagellus erythrinus , Mullus barbatus) examined. The frequency of occurrence of ingested microplastics was 46.25% in mussels, while among fish species, S. pilchardus showed the highest frequency of microplastic ingestion (47.2%). Microplastic abundance ranged from 1.7–2 items/individual in mussels and from 1.5–1.9 items/individual in fish. The majority of ingested microplastics were fragments, while their color and size varied. Fourier Transform Infrared Spectroscopy (FT-IR) indicated polyethylene as the most common polymer type in mussels and fish. Results can be used to set baseline levels for the assessment of microplastic pollution in the Ionian Sea. Highlights • Microplastics were detected in commercial species from the Northern Ionian Sea. • Sardines and mussels presented the highest frequency of occurrence of ingested microplastics. • Polyethylene is the most common polymer detected in the species investigated. [ABSTRACT FROM AUTHOR]

Microplastics (<5 mm) have been found in many fish species, from most marine environments. However, the mechanisms underlying microplastic ingestion by fish are still unclear, although they are important to determine the pathway of microplastics along marine food webs. Here we conducted experiments in the laboratory to examine microplastic ingestion (capture and swallowing) and egestion by juveniles of the planktivorous palm ruff, Seriolella violacea (Centrolophidae). As expected, fish captured preferentially black microplastics, similar to food pellets, whereas microplastics of other colours (blue, translucent, and yellow) were mostly co-captured when floating close to food pellets. Microplastics captured without food were almost always spit out, and were only swallowed when they were mixed with food in the fish's mouth. Food probably produced a ‘gustatory trap’ that impeded the fish to discriminate and reject the microplastics. Most fish (93% of total) egested all the microplastics after 7 days, on average, and 49 days at most, substantially longer than food pellets (<2 days). No acute detrimental effects of microplastics on fish were observable, but potential sublethal effects of microplastics on the fish physiological and behavioural responses still need to be tested. This study highlights that visually-oriented planktivorous fish, many species of which are of commercial value and ecological importance within marine food webs, are susceptible to ingest microplastics resembling or floating close to their planktonic prey. [ABSTRACT FROM AUTHOR]

The rapid increase in plastic use over the last few decades has resulted in plastic pollution in freshwater and marine ecosystems. However, more attention has been paid to plastic pollution in marine ecosystems than to freshwater ecosystems. This research determined microplastic ingestion by Daphnia magna and the potential effect of microplastics on the organism's survival and reproduction. The study also examined the potential of microplastics to enhance algal growth in support of understanding effects of microplastic ingestion on the organism. When exposed to 25, 50, and 100 mg/L fluorescent green polyethylene microbeads at size of 63–75 μm, D. magna ingested significant amount of plastic microbeads. The number of ingested beads increased with increasing particle concentration and exposure time. However, no significant effect on survival and reproduction was observed although the gut of D. magna was filled with plastic microbeads. In the algal experiment, Raphidocelis subcapitata grew more in the exposure media with the present of plastic microbeads than without plastic microbeads. This result suggests that plastic microbeads could serve as substrates for R. subcapitata to grow. Raphidocelis subcapitata then could be transferred to the organism's gut and provided energy for survival and reproduction. Results of the present study add to the literature of microplastic ingestion by aquatic organisms. Caution should be taken when interpreting hazards of microplastics based on ingestion, such as the measurement unit and the presence of algae in the environment. [ABSTRACT FROM AUTHOR]

Microplastic (MP) ingestion has been reported in a wide variety of organisms, however, its spatial occurrence and effects on wild populations remain quite unknown. The present study targets an economically and ecologically key species in the Mediterranean Sea, the shrimp Aristeus antennatus . 39.2% of the individuals sampled had MP in their stomachs, albeit in areas close to Barcelona city the percentage reached values of 100%. Overall, MP ingestion was confirmed in a wide spatial and depth (630–1870 m) range, pointing out the great dispersion of this pollutant. The benthophagous diet and close relationship with the sea bottom of A. antennatus might enhance MP exposure and ultimately lead to accidental ingestion. Detailed analysis of shrimps' diet revealed that individuals with MP had a higher presence of endobenthic prey. Microplastic fibers are probably retained for long periods due to stomach's morphology, but no negative effects on shrimp's biological condition were observed. [ABSTRACT FROM AUTHOR]

Human settlements within the Antarctic continent have caused significant coastal pollution by littering plastic. The present study assessed the potential presence of microplastics in the gastrointestinal tract of the Antarctic fish Harpagifer antarcticus , endemic to the polar region, and in the sub-Antarctic fish Harpagifer bispinis. H. antarcticus. A total of 358 microfibers of multiple colors were found in 89 % of H. antarcticus and 73 % of H. bispinis gastrointestinal track. A Micro-FTIR analysis characterized a sub-group (n = 42) of microfibers. It revealed that most of the fibers were cellulose (69 %). Manmade fibers such as microplastics polyethylene terephtalate, acrylics, and semisynthetic/natural cellulosic fibers were present in the fish samples. All the microfibers extracted were textile fibers of blue, black, red, green, and violet color. Our results suggest that laundry greywater discharges of human settlements near coastal waters in Antarctica are a major source of these pollutants in the Antarctic fish. [Display omitted] • 358 microfibers of multiple colors were found in the gastrointestinal tract of fish. • 69 % of microfibers were characterized as cellulose, followed by PET and acrylic microfibers. • 89 % of Harpagifer antarcticus gastrointestinal tract presented a high abundance of microfibers. [ABSTRACT FROM AUTHOR]

Microplastic presence in aquatic environments is a major problem globally. This study quantified microplastic abundances in fish species across two systems in South Africa around wastewater treatment works. Fish (n = 163) were examined for microplastic in gills and gastrointestinal tracts. Microplastic levels were generally low during the cool–dry season (mean 11.0 – 34.0 particles per fish taxon), and high during the hot–wet season (mean 10.0 – 119.0 particles per fish taxon). The microplastic concentrations per fish were similar between these systems, with downstream of wastewater treatment plants having high microplastic abundances. Although benthopelagic feeders were dominant, pelagic feeders had high microplastic abundances (range 20–119 particles), followed by benthopelagic (range 10–110 particles) and demersal (22 particles) feeders. Multiple regression analysis revealed a significant positive relationship between fish standard length and total microplastic levels, which suggests fish consume more microplastics due to increased food demand as a result of growth. • Mean microplastic abundances were low during the cool–dry season, and high in hot–wet season. • Downstream of the wastewater treatment plants had significantly higher microplastic abundances. • Pelagic feeders were the most commonly sampled and had high microplastic abundances. • Microplastic samples were dominated by fibres which were mostly transparent in colour. • A significant positive relationship between fish standard length and total microplastic abundances was observed. [ABSTRACT FROM AUTHOR]

This study evaluated the influence of foraging preferences on microplastic ingestion by six marine fish species from the Texas Gulf Coast. A total of 1381 fish were analyzed and 42.4% contained ingested microplastic, inclusive of fiber (86.4%), microbead (12.9% %), and fragment (< 1.0%) forms. Despite a substantial overlap in diet, ordination of ingested prey items clustered samples into distinctive species groupings, reflective of the foraging gradient among species. Orthopristis chrysoptera displayed the lowest overall frequency of microplastic ingestion and the most distinctive ordination grouping, indicating their selective invertebrate foraging preferences. Cluster analysis of O. chrysoptera most closely classified microplastic with the ingestion of benthic invertebrates, whereas the ingestion of microplastic by all other species most closely classified with the ingestion of vegetation and shrimp. O. chrysoptera , as selective invertebrate foragers, are less likely to ingest microplastics than species exhibiting generalist foraging preferences and methods of prey capture. [ABSTRACT FROM AUTHOR]

This study summarises the status of microplastic research in marine and freshwater specimens in natural museum collections around the world. Abundances, distributions, and types of microplastics in the archived collections are discussed. Museum collections can fill knowledge gaps on evolution of microplastic pollution before and during the Plasticene era. The specimens in these studies, ranging from plankton to vertebrates, were collected and archived between 1900 and 2019, and are dominated by specimens from marine ecosystems. All the specimens included in this review were preserved by freezing or in ethanol/formaldehyde except for specimens in one study that were preserved via cryomilling. Microfibers were the most common microplastics in the reviewed studies. We recommend more microplastic studies over a wider taxonomic range of species and across a longer span of years utilizing archival specimen collections around the world in order to establish reference points and develop temporal trends for microplastic pollution of the environment. • Abundance and distribution of microplastics (MP) in museum specimens are reviewed. • Microplastics in archived specimens may provide data on temporal trends. • Microplastic fibers are the most common MP type in studied museum specimens. [ABSTRACT FROM AUTHOR]

This study investigated the diet composition and microplastic contamination in six fish species collected from the creek area of northeastern Arabian Sea. The results show that the diet of the fish is mainly composed of shrimps, algae, fish, and zooplankton, with microplastics constituting up to 4.83 % (Index of Preponderance) of their diet. The average abundance of microplastics ranges from 5.82 to 7.69 items per fish, and their ingestion is influenced by seasonal variation, gut fullness, and trophic level. Microplastic contamination has no significant effect on the condition factor and hepatosomatic index of the fish species. However, polymer hazard index indicates that microplastic pollution in fish is associated with a low to high risk factor, which might cause potential harm to aquatic lives and higher vertebrates via food chain. Therefore, this study highlights the need for immediate attention and effective regulations to reduce microplastic pollution to protect marine life. • The current study characterizes the diet composition of selected fish species using the vacuity index (VI), index of preponderance (%IOP), and trophic level (TrL). • The most preferred prey items of the studied fishes are shrimps followed by algae, fish, and zooplankton. • The mean abundance of microplastics (MPs) in the selected fishes ranges from 5.82 to 7.69 items/individual. • Microplastic contamination has no significant effect on condition factor (K) and hepatosomatic index (HSI). • The polymer hazard index reveals a low to high level of threat associated with microplastic contamination. [ABSTRACT FROM AUTHOR]