Combined polystyrene microplastics and chlorpyrifos decrease levels of nutritional parameters in muscle of rainbow trout (Oncorhynchus mykiss)

Exploring the detrimental effects of microplastics on Asian seabass (Lates calcarifer) fingerlings survival and health

Microplastics (MPs) are widely used and disposed of indiscriminately, posing a potential threat to aquatic life. Herein, Asian seabass (Lates calcarifer) fingerlings were exposed to various concentrations (1, 10 and 100 ppt or g/kg) of dietary polyethylene MPs for 16 days. The results indicated a significant increase in mortality among the fish fed with dietary MPs compared to the control. Furthermore, histological analysis of the liver revealed moderate-to-severe morphological alterations, hepatocyte necrosis and vacuolisation as the concentration gradient of MPs increased. The severity of the alterations was highest at a concentration of 100 ppt, indicating a direct correlation between MP and liver damage. In addition, RNA sequencing and Gene Ontology term enrichment analysis revealed that a total of 4137 genes were significantly differentially expressed, with 1958 upregulated and 2179 downregulated genes. The significantly enriched terms included 'oxidoreductase activity', 'endocytosis', 'mitochondrial', 'immune system process' and 'lipid catabolic process'. Moreover, the Kyoto Encyclopaedia of Genes and Genomes enrichment analysis demonstrated that dietary MPs triggered oxidative stress, immune response and adaptive mechanism pathways in fish. Thus, MPs can induce metabolic disorders in L. calcarifer, highlighting their potential threat to aquatic organisms.

Investigating the effects of microplastics on the metabolism of Trematomus bernacchii from the ross sea (Antarctica)

Microplastic pollution is a growing environmental issue, even reaching remote areas like the Arctic and Antarctic, posing threats to biodiversity and food chains. The present research represents a pioneering endeavor aimed at exploring the relationship between lipids and microplastics in 20 wild specimens of Trematomus bernacchii from the Ross Sea (Antarctica). Fish were grouped in MPs-ingested and MPs-free based on whether they had ingested microplastics. Raman spectroscopy revealed that contaminated fish samples contained from one to three different types of polymeric fibers (1.4 items/specimen, ± = 0.7), specifically, polyester (PES), polypropylene (PP), and polyethylene terephthalate (PET). Gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID) techniques were employed for the study of the lipid composition in term of fatty acids methyl esters (FAMEs). Fifty different FAME compounds were identified and quantified in the lipid fraction extracted from the muscle tissues of the selected fish samples. Polyunsaturated fatty acids (PUFAs) are the most abundant family of fatty acids in T. bernacchii species with eicosapentaenoic (C20:5ω3) and docosahexaenoic (C22:6ω3) acids as main components. In detail, PUFA class accounted for 46.78 ± 6.82% and 44.62 ± 4.86% of the total fatty acid composition in MPs-ingested and MPs-free groups, respectively. The contents of the monounsaturated fatty acids (MUFAs) and saturated fatty acids (SFAs) varied from 27.93% to 31.15% and from 24.23% to 25.05% in MPs-ingested and MPs-free fish samples, respectively. Based on Mann-Whitney test results (p < 0.05), there was no significant difference from a statistical point of view between two groups of fishes. Additionally, nutritional quality indices exhibited comparable values between groups. Results showed that no significant differences were found in the fatty acids distribution between the two groups. This indicates that the lipid composition of wild fish that are naturally exposed to plastic pollution remains unchanged and could still have beneficial effects on human health.

Evaluation of Bisphenol S (BPS) toxicity on the reproductive system of Channa striatus: Insights for environmental risk assessment

Aquatic ecosystems face significant exposure to endocrine-disrupting chemicals (EDCs), which can mimic, block, or alter the synthesis of endogenous hormones. Bisphenol A (BPA), a widely known EDC, has been phased out from consumer products due to concerns about its potential impacts on human health. In its place, bisphenol S (BPS), an organic compound, has been increasingly used in the production of polycarbonate plastics, epoxy resins, thermal receipt papers, and currency. Vitellogenin (Vtg), a yolk precursor protein synthesized in the liver and present in oviparous fish, particularly males, serves as a pertinent biomarker for studying the effects of estrogenic EDCs on fish. This study aimed to assess the impact of BPS on reproductive parameters and hepatic vitellogenin expression in Channa striatus. The LC50 of BPS was determined to be 128.8 mg/L. Experimental groups included control and BPS-exposed fish, with sub-lethal concentrations of BPS (1 mg/L, 4 mg/L, and 12 mg/L) administered and effects monitored at seven- and twenty-one-day intervals. Significant decreases in gonadosomatic index (GSI), ova diameter, and fecundity were observed in BPS-exposed Channa striatus. Hepatic Vtg mRNA expression was downregulated in female and upregulated in male following BPS exposure. Serum hormone analysis confirmed the estrogenic activity of BPS. These findings underscore BPS's ability as an endocrine disruptor to interfere with hormone synthesis and disrupt spermatogenesis and oogenesis processes in Channa striatus. This research contributes to understanding the endocrine-disrupting effects of BPS on aquatic organisms, highlighting potential ecological implications and the need for continued monitoring and regulatory considerations.

Diet composition and plastic ingestion in Poecilia reticulata from urban streams

Fish are excellent bioindicators and can reveal the presence of plastic in the environment. Diagnosing the composition and abundance of polymers in the fish diet makes it possible to evaluate their point sources and possible trophic transfers. We aimed to use the gastrointestinal contents of Poecilia reticulata in subtropical urban streams to detect the occurrence, shape, color, size, and chemical composition of polymers. For this, the diet of 240 individuals was analyzed using the volumetric method, and the microplastics (MPs; < 5 mm) recorded were characterized using Raman spectroscopy. Individuals predominantly consumed organic detritus and aquatic macroinvertebrates, with higher proportions of Diptera. A total of 111 plastic particles (< 0.5 to 12 mm) were recorded, and a subset of 14.4% was subjected to a micro-Raman spectrometer (830 nm excitation). The occurrence of polyethylene terephthalate (PET) and polypropylene (PP) with phthalocyanine dye was recorded. Some fragments could not be identified by Raman, but they contained indigo blue dye. Poecilia reticulata had a predominantly detritivorous diet with a record of plastic consumption, reflecting environmental pollution. Our results demonstrate that individuals of P. reticulata have ingested MPs in urban streams. This reinforces the need for future studies on the relationship between the presence of MPs in fish and the level of pollution in streams, comparisons with species of different feeding habits, and the potentially harmful effects on the entire biota.

Microplastic-stressor responses are rarely synergistic in freshwater fishes: A meta-analysis

Microplastic exposure can cause a range of negative effects on the biochemistry, condition and ecology of freshwater fishes depending on aspects of the exposure and the exposed fish. However, fishes are typically exposed to microplastics and additional multiple stressors simultaneously, for which the combined effects are poorly understood and may have important management consequences. Additive effects are those where the combined effect is equal to the sum, antagonistic where combined effects are less than the sum and for synergistic effects the combined effect is greater to the sum of the individual effects. Here, we performed a meta-analysis of studies recording freshwater fish responses to microplastic-stressor exposures to test if interactions were primarily non-additive (synergistic or antagonistic), and factors impacting the net response. Individual responses were classified (antagonistic/additive/synergistic) and the fit of net responses to a null additive model determined for 838 responses (36 studies) split by categorical variables for the microplastic exposure (environmental relevance, interacting stressor, microplastic morphology and response category measured), as well as the exposed fish (lifestage, ecology and family). Most responses were classified as antagonistic (48 %) and additive (34 %), with synergistic effects least frequent (17 %). Net responses fitted null additive models for all levels of interacting stressor, fish family and microplastic morphology. In contrast, net antagonism was present for biochemical responses, embryo lifestages, environmentally relevant microplastic exposures and fish with benthopelagic ecology, while synergism was identified for fishes with demersal ecology. While substantial knowledge gaps remain and are discussed, the data thus far suggest microplastic-stressor responses in freshwater fishes are rarely synergistic and, therefore, addressing either or both stressors will likely result in positive management and biological outcomes.

Microplastics derived from plastic mulch films and their carrier function effect on the environmental risk of pesticides

Plastic film mulching can maintain soil water and heat conditions, promote plant growth and thus generate considerable economic benefits in agriculture. However, as they age, these plastics degrade and form microplastics (MPs). Additionally, pesticides are widely utilized to control organisms that harm plants, and they can ultimately enter and remain in the environment after use. Pesticides can also be sorbed by MPs, and the sorption kinetics and isotherms explain the three stages of pesticide sorption: rapid sorption, slow sorption and sorption equilibrium. In this process, hydrophobic and partition interactions, electrostatic interactions and valence bond interactions are the main sorption mechanisms. Additionally, small MPs, biodegradable MPs and aged conventional MPs often exhibit stronger pesticide sorption capacity. As environmental conditions change, especially in simulated biological media, pesticides can desorb from MPs. The utilization of pesticides by environmental microorganisms is the main factor controlling the degradation rate of pesticides in the presence of MPs. Pesticide sorption by MPs and size effects of MPs on pesticides are related to the internal exposure level of biological pesticides and changes in pesticide toxicity in the presence of MPs. Most studies have suggested that MPs exacerbate the toxicological effects of pesticides on sentinel species. Hence, the environmental risks of pesticides are altered by MPs and the carrier function of MPs. Based on this, research on the affinity between MPs and various pesticides should be systematically conducted. During agricultural production, pesticides should be cautiously selected and used plastic film to ensure human health and ecological security.

Changes in Flavor-Related Biomarkers in Pacific Oysters (Crassostrea gigas) Following Microplastic Exposure

Microplastics have been an emerging threat to filtering species and the ingestion and impacts of microplastics on oysters are a cause for concern. However, much remains unknown about the effects of microplastics on flavor-related biomarkers in oysters. Herein, a laboratory microplastic exposure with concentrations of 1, 10, and 100 mg/L for 15 days was performed to investigate the impacts of microplastics on the flavor parameters of oysters. Exposure to microplastics changed the odor characteristics of oysters. Microplastic exposure had minor effects on the fatty acid composition; however, significant alterations in free amino acids and nucleotides were observed under the 1 and 10 mg/L exposure groups, respectively. The overall results indicated 10 mg/L of microplastic exposure significantly increased the equivalent umami value of oysters. These findings stressed the effects of microplastics on oysters and would be an important reference for the assessment of the potential risks associated with microplastics in marine edible species.

Multi-omics analysis reveals the toxic mechanism of ammonia-enhanced Microcystis aeruginosa exposure causing liver fat deposition and muscle nutrient loss in zebrafish

Microcystis aeruginosa and ammonia pollution are two important environmental stress factors in water eutrophication. Herein, we simulated environmental conditions to investigate the effects of chronic exposure (single and combined) to M. aeruginosa and total ammonia nitrogen (TAN) on lipid metabolism and muscle quality in zebrafish. Our results showed that M. aeruginosa and TAN significantly induced lipid deposition and tissue damage in the liver of zebrafish. Liver transcriptomic analysis revealed that M. aeruginosa and TAN disrupted the balance in lipid synthesis, decomposition, and transport, ultimately leading to hepatic lipid accumulation. Moreover, exposure to M. aeruginosa or TAN alone resulted in decreased crude protein content and increased lipid content in muscle, as well as disrupted muscle fatty acid composition. Metabolomic analysis of muscle revealed significant alterations in metabolites such as glycerolipids, glycerophospholipids and fatty acids. The co-exposure of M. aeruginosa and TAN had a more significant effect on liver lipid dysfunction and muscle quality deterioration in zebrafish. These findings provide valuable insights into the potential risks and hazards of M. aeruginosa and TAN in eutrophic water bodies subject to Microcystis blooms, and can help inform effective strategies for monitoring and managing these toxins in aquatic ecosystems.

Synergetic effects of polyethylene microplastic and abamectin pesticides on the eyes of zebrafish larvae and adults through activation of apoptosis signaling pathways

Although the toxicity of microplastics (MPs) and pesticides has recently been described, the possible effects of combining these pollutants are poorly understood. Thus, we evaluated the potential impact of exposure to polyethylene MP (PE-MP) and abamectin (ABM) (alone and combined) in zebrafish. After five days, the combined exposure to MP and ABM decreased the survival rate compared to exposures to individual pollutants. A significant increase in reactive oxygen species (ROS), lipid peroxidation, apoptosis, and impairment in antioxidant response was observed in zebrafish larvae. Morphological changes in the eyes of zebrafish significantly increased in the combined exposure group than in the individual exposure. Furthermore, the bax and p53 expression (specific apoptotic genes) was significantly upregulated after the combined exposure to PE-MP and ABM. So, the synergetic effect of MP and ABM cannot be ignored, and further research on other higher models is required to confirm its consequences.

Nano- and Microplastics Migration from Plastic Food Packaging into Dairy Products: Impact on Nutrient Digestion, Absorption, and Metabolism

The ongoing use of plastic polymers to manufacture food packaging has raised concerns about the presence of nano- and microplastics (NMPs) in a variety of foods. This review provides the most recent data on NMPs' migration from plastic packaging into dairy products. Also discussed are the possible effects of NMPs on nutrient digestion, absorption, and metabolism. Different kinds of dairy products, including skimmed milk, whole liquid milk, powder milk, and infant formula milk, have been found to contain NMPs of various sizes, shapes, and concentrations. NMPs may interact with proteins, carbohydrates, and fats and have a detrimental impact on how well these nutrients are digested and absorbed by the body. The presence of NMPs in the gastrointestinal tract may impact how lipids, proteins, glucose, iron, and energy are metabolized, increasing the risk of developing various health conditions. In addition to NMPs, plastic oligomers released from food packaging material have been found to migrate to various foods and food simulants, though information regarding their effect on human health is limited. Viewpoints on potential directions for future studies on NMPs and their impact on nutrient digestion, absorption, and health are also presented in this review.

Effects of microplastics, pesticides and nano-materials on fish health, oxidative stress and antioxidant defense mechanism

Microplastics and pesticides are emerging contaminants in the marine biota, which cause many harmful effects on aquatic organisms, especially on fish. Fish is a staple and affordable food source, rich in animal protein, along with various vitamins, essential amino acids, and minerals. Exposure of fish to microplastics, pesticides, and various nanoparticles generates ROS and induces oxidative stress, inflammation, immunotoxicity, genotoxicity, and DNA damage and alters gut microbiota, thus reducing the growth and quality of fish. Changes in fish behavioral patterns, swimming, and feeding habits were also observed under exposures to the above contaminants. These contaminants also affect the Nrf-2, JNK, ERK, NF-κB, and MAPK signaling pathways. And Nrf2-KEAP1 signalling modulates redox status marinating enzymes in fish. Effects of pesticides, microplastics, and nanoparticles found to modulate many antioxidant enzymes, including superoxide dismutase, catalase, and glutathione system. So, to protect fish health from stress, the contribution of nano-technology or nano-formulations was researched. A decrease in fish nutritional quality and population significantly impacts on the human diet, influencing traditions and economics worldwide. On the other hand, traces of microplastics and pesticides in the habitat water can enter humans by consuming contaminated fish which may result in serious health hazards. This review summarizes the oxidative stress caused due to microplastics, pesticides and nano-particle contamination or exposure in fish habitat water and their impact on human health. As a rescue mechanism, the use of nano-technology in the management of fish health and disease was discussed.

Microplastics in water, feed and tissues of European seabass reared in a recirculation aquaculture system (RAS)

Plastic particles (PLs) are ubiquitous in aquatic ecosystems and aquaculture production is susceptible to contamination from external or endogenous sources. This study investigated PL presence in water, fish feed and body sites of 55 European seabass produced in a recirculating aquaculture system (RAS). Fish morphometric parameters and health status biomarkers were determined. A total of 372 PLs were recovered from water (37.2 PL/L), 118 PLs from feed (3.9 PL/g), and 422 from seabass (0.7 PL/g fish; all body sites analysed). All 55 specimens had PLs in at least two of the four body sites analysed. Concentrations were higher in the gastrointestinal tract (GIT; 1.0 PL/g) and gills (0.8 PL/g) than in the liver (0.8 PL/g) and muscle (0.4 PL/g). PL concentration in GIT was significantly higher than in muscle. Black, blue, and transparent fibres made of man-made cellulose/rayon and polyethylene terephthalate were the most common PLs in water and seabass, while black fragments of phenoxy resin were the most common in feed. The levels of polymers linked to RAS components (polyethylene, polypropylene, and polyvinyl chloride) were low suggesting a limited contribution to the overall PL levels found in water and/or fish. The mean PL size recovered from GIT (930 μm) and gills (1047 μm) was significantly larger than those found in the liver (647 μm) and dorsal muscle (425 μm). Considering all body sites, PLs bioconcentrated in seabass (BCF_Fish >1) but their bioaccumulation did not occur (BAF_Fish <1). No significant differences were observed in oxidative stress biomarkers between fish with low (<7) and high (≥7) PL numbers. These findings suggest that fish produced in RAS are mainly exposed to MPs through water and feed. Further monitoring under commercial conditions and risk assessment are warranted to identify potential threats to fish and human health and define mitigating measures.

Effects of polystyrene microplastics acute exposure in the liver of swordtail fish (Xiphophorus helleri) revealed by LC-MS metabolomics

As global pollution, microplastics pollution has aroused growing concerns. In our experiment, the effect of microplastics acute exposure on the liver of swordtail fish was investigated by using LC-MS metabolomics. Fishes treated with high concentration polystyrene microspheres (1 μm) for 72 h were divided into three concentration groups: (A) no microplastics, (B): 1 × 10⁶ microspheres L^-1, (C): 1 × 10⁷ microspheres L^-1. Metabolomic analysis indicated that exposure to microplastics caused alterations of metabolic profiles in swordtail fish, including 37 differential metabolites were identified in B vs. A, screened out ten significant metabolites, which involved 14 metabolic pathways. One hundred three differential metabolites were identified in C vs. A, screened out 16 significant metabolites, which involved 30 metabolic pathways. Six significant metabolites were overlapping in group B vs. A and C vs. A; they are 3-hydroxyanthranilic acid, l-histidine, citrulline, linoleic acid, pantothenate, and xanthine. In addition, four metabolic pathways are overlapping in group B vs. A and C vs. A; they are beta-alanine metabolism, biosynthesis of amino acids, linoleic acid metabolism, and aminoacyl-tRNA biosynthesis. These differential metabolites were involved in oxidative stress, immune function, energy metabolism, sugar metabolism, lipid metabolism, molecule transport, and weakened feed utilization, growth performance, nutrient metabolism, and animal growth. Furthermore, we found that the number of interfered amino acids and microplastics showed a dose-effect. In summary, great attention should be paid to the potential impact of microplastics on aquatic organisms.

Short-Term Exposure to MPs and DEHP Disrupted Gill Functions in Marine Bivalves

The synergistic impact of microplastics (MPs) and organic pollutants remains poorly understood in the marine environment. This study aimed to assess the toxicity of polypropylene microplastics (PS) and/or di-(2-ethylhexyl) phthalate (DEHP) on marine clams. Both Ruditapes philippinarum and Tegillarca granosa were exposed to PS and DEHP individually and combined at environmentally relevant concentrations for 48 h. The filtration rate, antioxidant enzymes activity, lipid peroxidation, reactive oxygen species accumulation, and histological alterations were evaluated. Our results show that single or co-exposure to MPs and DEHP significantly decreases the filtration rate in both type of clams, but the latter exhibited stronger inhibition effect. Close examination of accumulation of reactive oxygen species and related biomarkers revealed that combined exposure exerts greater oxidative stress in the cells, which causes more serious histopathological damage in the gills of the bivalves. Our study implies that MPs, in synergy with organic pollutants, can be more harmful for marine organisms.

Microplastic ingestion evidence by economically important farmed fish species from Turkey

Microplastic pollution and its potential impacts on humans become a global concern. This study is the first study examining the microplastic ingestion in the commercially important species Oncorhynchus mykiss Rainbow trout (Walbaum, 1792), Sparus aurata Gilthead seabream Linnaeus, 1758, and Dicentrarchus labrax European seabass (Linnaeus, 1758) from Turkey. The occurrence frequency of microplastic (MP)in the gastrointestinal tract (GIT) was varied between 50 and 63 %. The highest MP abundance in the GIT was estimated in Rainbow trout (1.2 MPs individual^-1) followed by European seabass (0.95 MPs individual^-1) and Gilthead seabream (0.8 MPs individual^-1). Most of the extracted microplastic particles were black (61 %) and blue (27 %) in color and fiber (80 %) in shape. Major identified polymers were polyethylene (25 %), polyester (20 %), polyamide (10 %). Since fish consumption is an important route for MPs, results light up the danger potential for humans. This study will fill the information gap in Turkey and show the necessity of protection measures in aquaculture industry.

Investigation of long-term bisphenol A exposure on rainbow trout (Oncorhynchus mykiss): Hematological parameters, biochemical indicator, antioxidant activity, and histopathological examination

As an industrial synthetic chemical, bisphenol A (BPA) has the potential to have physiologically and histologically adverse effects on aquatic organisms. BPA causes the reproductive disrupting of all vertebrates due to its degradation on endocrine system. Therefore, the effect of BPA on fish with high economic value is an important issue. This study focused weekly on long-term BPA exposure on rainbow trout (Oncorhynchus mykiss). Hematological, biochemical, antioxidant activity and histopathological examinations were performed on O. mykiss exposed to 1000 μg/L BPA concentration. Mortality was observed in the BPA group during the first three weeks. As a result of hematological studies, leukocyte count and hemoglobin in the BPA group were significantly higher in the first three weeks compared to the control group. Plasma cortisol level as a biochemical indicator showed a similar trend to leukocyte and hemoglobin. There was no significant difference between BPA and control groups in terms of superoxide dismutase and catalase. However, glutathione peroxidase activity in the BPA group was significantly lower than in the control group for four weeks. At the end of the study, many alterations were observed histologically in the gill tissues. While more intense hyperplasia and epithelial lifting were observed in the tissues in the BPA group compared to the control group, vacuolization, necrosis and hypertrophy were observed infrequently. In conclusion, this study argues that BPA causes negative effects on O. mykiss in terms of fish welfare and future study should be focused on its environmental adaptation with color preference patterns.

Occurrence of microplastics in gastrointestinal tracts of planktivorous fish from the Thoothukudi region

Planktivorous fish are easily susceptible to passive microplastic ingestion during their feeding behaviour and may be transferred along with the marine food web. Hence, the present study was conducted to assess the microplastics prevalence in the planktivorous fish (677 individuals) collected from 2 landing centres in the Thoothukudi, Gulf of Mannar region, South Tamil Nadu, India. The prevalence of microplastics was detected in 118 out of 677 individuals, with a mean abundance and percent occurrence of 1.22 ± 0.47 items/individual and 17%, respectively. The ingestion of microplastics in planktivorous fish was primarily due to their feeding habitat, in which they were prone to the accidental or passive intake of microplastics regardless of the fish's length and body weight. The microplastics abundance was significantly higher in Sardinella gibbosa (1.34 ± 0.56 items/individual), which might be due to their pelagic and planktivorous feeding habitat, highest filtration capacity, presence of closed gill rakers, and also due to the passive ingestion of microplastics as food items. Fibres, blue, and 1 to 2mmsized microplastics were predominant in the guts of Sardinella gibbosa, accounting for 95.74, 47.87, and 46.80%, respectively, whereas in Leiognathus lineolatus, fragments, black, and 1 to 2mmsized microplastics were highly prevalent with 62.96, 72.22, and 79.62%, respectively. The predominance of various shapes (fragments, fibres), sizes (1-2 mm), and colours (blue and black) of microplastics in the guts of fish was influenced by their passive ingestion, ingestion of contaminated planktonic prey, lack of selectivity of prey particles and their resemblance to plankton species. Polypropylene polymers predominated (96.77% and 95.23%) in both fish, followed by polystyrene (3.22% and 4.76%). Furthermore, this study provides baseline data and insists that there is a need for continuous monitoring of the distribution of microplastics.

Microplastics increase the accumulation of phenanthrene in the ovaries of marine medaka (Oryzias melastigma) and its transgenerational toxicity

Microplastics (MPs) are considered to exacerbate the impacts of hydrophobic organic pollutants on aquatic organisms through the carrier function, but whether MPs affect the transgenerational toxicity of pollutants is unclear. This study exposed adult female marine medaka to phenanthrene (Phe)-adsorbed MPs for 60 days to investigate the effects of MPs on the bioaccumulation, reproductive and transgenerational toxicity of Phe. Compared to Phe alone, co-exposure to Phe and 200 μg/L MPs significantly increased Phe bioaccumulation in the intestines and ovaries. Phe alone and Phe combined with MPs disrupted the regulation of the hypothalamus-pituitary-gonadal axis, and reduced vitellogenin levels and reproductive capacity of female fish. In particular, co-exposure to 200 μg/L MPs and Phe increased the rate of follicular atresia, inhibited ovarian maturity, and aggravated reproductive toxicity. Notably, maternal uptake of Phe could be transferred to the offspring, and embryonic accumulation increased with the concentrations of MPs. Moreover, MPs aggravated Phe-induced bradycardia in embryos, suggesting that MPs exacerbated the transgenerational toxicity of Phe. These findings reveal that the growing number of MPs in the ocean might amplify the adverse effects of organic pollutants on the health and population stability of marine fishes, and this problem merits more attention.

Microplastics reduce the bioaccumulation and oxidative stress damage of triazole fungicides in fish

Microplastics (MPs) and pesticides are typical representatives of harmful chemicals in polluted waters. It is understood that the combined toxicity may differ from that of a single toxic substance. Although their combined toxicities on aquatic organisms have practical significance and research value, they have received little attention due to their complicated interaction, and the mechanism has rarely been reported. In this paper, we designed a study to investigate the single and combined effects of polystyrene microplastics (PS-MPs) and the triazole fungicide difenoconazole on zebrafish, and to explore the mechanism of this effect. The results showed that PS-MPs could reduce the bioaccumulation of difenoconazole in zebrafish to a certain extent and alleviate the oxidative stress damage of difenoconazole in the zebrafish liver. The transcriptome and qRT-PCR data revealed the association of multiple pathways in the difenoconazole response, while the presence of PS-MPs ameliorated this effect in gene expression changes. Due to the properties of PS-MPs and the interaction between them, the toxic effect of difenoconazole when combined with PS-MPs is more prominent. These results provide a novel aspect to understand the environmental behavior of MPs and to evaluate the combined effect of MPs and pesticides on aquatic food.