Individual and combined toxicogenetic effects of microplastics and heavy metals (Cd, Pb, and Zn) perturb gut microbiota homeostasis and gonadal development in marine medaka (Oryzias melastigma)

Polystyrene microplastics trigger testosterone decline via GPX1

As an emerging environmental endocrine disruptor, polystyrene microplastics (PS-MPs) are considered to have the anti-androgenic feature and impair male reproductive function. To explore the adverse effects of PS-MPs on testosterone synthesis and male reproduction and further elucidate underlying mechanisms, BALB/c mice and Leydig cells were employed in the present work. The results indicated that 50 μm PS-MPs accumulated in mouse testes and were internalized into the cytoplasm. This not only damaged the testicular histomorphology and ultrastructure, but also reduced the viability of Leydig cells and the serum level of GnRH, FSH, LH, and testosterone. After PS-MPs exposure, the ubiquitination degradation and miR-425-3p-targeted modulation synergistically contributed to the suppression of GPX1, which induced oxidative stress and subsequently activated the PERK-EIF2α-ATF4-CHOP pathway of endoplasmic reticulum (ER) stress. The transcription factor CHOP positively regulated the expression of SRD5A2 by directly binding to its promoter region, thereby accelerating testosterone metabolism and ultimately lowing testosterone levels. Besides, PS-MPs compromised testosterone homeostasis via interfering with the hypothalamic-pituitary-testis (HPT) axis. Taken together, PS-MPs possess an anti-androgenic characteristic and exert male reproductive damage effects. The antioxidant enzyme GPX1 plays a crucial role in the PS-MPs-mediated testosterone decline.

Pollution-related changes in nest microbiota: Implications for growth and fledging in three passerine birds

Non-ferrous smelters emit toxic metals into the environment, posing a threat to wildlife health. Despite the acknowledged role of microbes in host health, the impact of such emissions on host-associated microbiota, especially in wild birds, remains largely unexplored. This study investigates the associations of metal pollution, fitness, and nest microbiota (serving as a proxy for early-life microbial environment) which may influence the nestling health and development. Our study focuses on three passerine birds, the great tit (Parus major), blue tit (Cyanistes caeruleus), and pied flycatcher (Ficedula hypoleuca), within control and metal-polluted sites around a Finnish copper-nickel smelter. The polluted sites had been contaminated with arsenic (As), cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn). We performed bacterial 16S rRNA sequencing and metal analyses on 90 nests and monitored nestling body mass, fledging success, and various biotic and abiotic factors. Our findings revealed species-specific responses to metal exposure in terms of both fitness and nest microbiota. P. major and C. caeruleus showed sensitivity to pollution, with decreased nestling growth and fledging in the polluted zone. This was accompanied by a shift in the bacterial community composition, which was characterized by an increase in some pathogenic bacteria (in P. major and C. caeruleus nests) and by a decrease in plant-associated bacteria (within C. caeruleus nests). Conversely, F. hypoleuca and their nest microbiota showed limited responses to pollution, indicating greater tolerance to pollution-induced environmental changes. Although pollution did not correlate with nest alpha diversity or the most abundant bacterial taxa across all species, certain potential pathogens within the nests were enriched in polluted environments and negatively correlated with nestling fitness parameters. Our results suggest that metal pollution may alter the nest bacterial composition in some bird species, either directly or indirectly through environmental changes, promoting pathogenic bacteria and potentially impacting bird survival.

Factors influencing the distribution, risk, and transport of microplastics and heavy metals for wildlife and habitats in "island" landscapes: From source to sink

Microplastics (MPs) and heavy metals (HMs) are important pollutants in terrestrial ecosystems. In particular, the "island" landscape's weak resistance makes it vulnerable to pollution. However, there is a lack of research on MPs and HMs in island landscapes. Therefore, we used Helan Mountain as the research area. Assess the concentrations, spatial distribution, ecological risks, sources, and transport of MPs and HMs in the soil and blue sheep (Pseudois nayaur) feces. Variations in geographical distribution showed a connection between human activity and pollutants. Risk assessment indicated soil and wildlife were influenced by long-term pollutant polarization and multi-element inclusion (Igeo, Class I; PHI, Class V; RI (MPs), 33 % Class II, and 17 % Class IV; HI = 452.08). Source apportionment showed that tourism and coal combustion were the primary sources of pollutants. Meanwhile, a new coupling model of PMF/Risk was applied to quantify the source contribution of various risk types indicated transportation roads and tourism sources were the main sources of ecological and health risks, respectively. Improve the traceability of pollution source risks. Furthermore, also developed a novel tracing model for pollutant transportation, revealing a unique "source-sink-source" cycle in pollutant transportation, which provides a new methodological framework for the division of pollution risk areas in nature reserves and the evaluation of spatial transport between sources and sinks. Overall, this study establishes a foundational framework for conducting comprehensive risk assessments and formulating strategies for pollution control and management.

Microplastics at an environmentally relevant dose enhance mercury toxicity in a marine copepod under multigenerational exposure: Multi-omics perspective

Here, we subjected the marine copepod Tigriopus japonicus to environmentally-relevant concentrations of microplastics (MPs) and mercury (Hg) for three generations (F0-F2) to investigate their physiological and molecular responses. Hg accumulation and phenotypic traits were measured in each generation, with multi-omics analysis conducted in F2. The results showed that MPs insignificantly impacted the copepod's development and reproduction, however, which were significantly compromised by Hg exposure. Interestingly, MPs significantly increased Hg accumulation and consequently aggravated this metal toxicity in T. japonicus, demonstrating their carrier role. Multi-omics analysis indicated that Hg pollution produced numerous toxic events, e.g., induction of apoptosis, damage to cell/organ morphogenesis, and disordered energy metabolism, ultimately resulting in retarded development and decreased fecundity. Importantly, MPs enhanced Hg toxicity mainly via increased oxidative apoptosis, compromised cell/organ morphogenesis, and energy depletion. Additionally, phosphoproteomic analysis revealed extensive regulation of the above processes, and also impaired neuron activity under combined MPs and Hg exposure. These alterations adversely affected development and reproduction of T. japonicus. Overall, our findings should offer novel molecular insights into the response of T. japonicus to long-term exposure to MPs and Hg, with a particular emphasis on the carrier role of MPs on Hg toxicity.

Gut microbiota composition of the isopod Ligia in South Korea exposed to expanded polystyrene pollution

Plastics pose a considerable challenge to aquatic ecosystems because of their increasing global usage and non-biodegradable properties. Coastal plastic debris can persist in ecosystems; however, its effects on resident organisms remain unclear. A metagenomic analysis of the isopoda Ligia, collected from clean (Nae-do, ND) and plastic-contaminated sites (Maemul-do, MD) in South Korea, was conducted to clarify the effects of microplastic contamination on the gut microbiota. Ligia gut microbiota's total operational taxonomic units were higher in ND than in MD. Alpha diversity did not differ significantly between the two Ligia gut microbial communities collected from ND and MD, although richness (Observed species) was lower in MD than in ND. Proteobacteria (67.47%, ND; 57.30%, MD) and Bacteroidetes (13.63%, ND; 20.76%, MD) were the most abundant phyla found at both sites. Significant different genera in Ligia from EPS-polluted sites were observed. Functional gene analysis revealed that 19 plastic degradation-related genes, including those encoding hydrogenase, esterase, and carboxylesterase, were present in the gut microbes of Ligia from MD, indicating the potential role of the Ligia gut microbiota in plastic degradation. This study provides the first comparative field evidence of the gut microbiota dynamics of plastic detritus consumers in marine ecosystems.

Size-dependent effects of microplastics on intestinal microbiome for Perna viridis

Microplastics pollution threatens to marine organisms, particularly bivalves that actively ingest and accumulate microplastics of certain sizes, potentially disrupting intestinal homeostasis. This study investigated the microplastic abundance in wild and farmed mussels around Singapore, and examined the size-dependent effects of nano- to micro-scale polystyrene (0.5 µm/5 µm/50 µm) on the mussel intestinal microbiome in the laboratory. The field investigation revealed higher microplastic abundance in farmed mussels compared to wild ones. Experimentally, mussels exposed to 0.6 mg/L of microplastics for 7 days, followed by a 7-day depuration period, showed substantial impacts on Spirochaetes and Proteobacteria, facilitating the proliferation of pathogenic species and differentially affecting their pathogenic contributions. Metagenomics analysis revealed that microplastic exposure reduced Spirochaeta's contribution to virulence and pathogenicity loss, did not affect Vibrio and Oceanispirochaeta's pathogenicity, and increased Treponema and Oceanispirochaeta's contributions to pathogenicity loss. Moreover, microplastics increased transmembrane transporters and impacted oxidative phosphorylation enzymes, impairing energy metabolism. These effects persisted after depuration, indicating lack of resilience in the microbiome. Nano- and micro-scale plastics perturbed the mussel microbiome composition and functions in a size-dependent manner, with nano-plastics being the most disruptive. The increasing use and sale of aquaculture equipment of plastic may exacerbate the intestinal dysbiosis in bivalves, which threatens consumers' health.

Long-term carbaryl exposure leads to behavioral abnormalities and reproductive toxicity in male marine medaka through apoptosis-mediated HPA and HPG axes dysregulation

Carbaryl is a widely used carbamate pesticide that has been detected in the marine environment, but its effects on marine fish are still unknown. This study was aimed to investigate the effects of long-term exposure of carbaryl on male marine medaka. For this purpose, we set up five exposure concentration groups of 0, 0.1, 1, 10, and 100 µg/L for 180 days. On the one hand, we observed increased aggression and decreased ability to avoid predators in males after exposure, which was affected by the levels of HPA-axis hormones, especially decreased cortisol level. On the other hand, after exposure, HPG axis hormone levels and gene transcription levels were disturbed. Males exhibited a decreased gonadosomatic index and a notable reduction in mature sperm proportion and the F1 generation displayed a significant increase in malformation rate. Additionally, the number of apoptotic cells and the transcription level of apoptosis-related genes in the brains of male marine medaka substantially increased after exposure. Apoptosis of brain cells may be responsible for the disturbance of HPA and HPG axes, consequently leading to behavioral and reproductive abnormalities. These findings provide novel insights into evaluating the toxic effects of carbaryl on male marine medaka and emphasizing the criticality of exploring the potential environmental risks posed by carbaryl in the marine environment, thus providing toxicity value basis for further strengthening marine environmental monitoring and the protection of biological resources.

Impact of polyvinyl chloride microplastic and paraquat herbicide on the blood cells, biochemical parameters, liver enzymes and morphological changes of aqueduct fish

In recent years, the surge in plastic production has led to pervasive pollution across all environments, earning us the title of inhabiting a "plastic world." Consequently, this research endeavors to explore alterations in biochemical parameters, liver enzymes, and tissue integrity within the gills, intestines, and liver of black fish subjected to polyvinyl chloride (PVC) microplastics and paraquat herbicide, both individually and in combination. For this purpose, we allocated 90 blackfish specimens into 9 groups consisting of 10 individuals each through random selection. Following a period of 28 days, we carried out an assessment to investigate the toxic effects of PVC and paraquat, both separately and in combination. Subsequently, The results indicate that the number of red blood cells (RBCs, millions/mm3) in all studied groups (Group G: 3.6 ± 0.18; Group H: 3.5 ± 0.17; and Group I: 3.2 ± 0.16) is significanly lower than the control group (Pvalue<0.05). The glucose levels in all studied groups (Group B: 47 ± 5.12; Group C: 48 ± 3.79; Group D: 51 ± 4.14; Group E: 48 ± 5.37; Group F: 53 ± 7.48; Group G: 53 ± 9.24; Group H: 58 ± 10.43; and Group I: 61 ± 8.71) are higher than the control group (46 ± 3.71). The results indicate that the levels of AST enzyme in all studied groups (group B: 30 ± 0.17; group C: 32 ± 1.61; group D: 34 ± 1.92; group E: 33 ± 1.17; group F: 38 ± 2.27; group G: 38 ± 1.71; group H: 43 ± 2.15; and group I: 46 ± 2.33). Groups F, G, H, and I exhibit significantly higher levels of AST enzyme compared to the control group, with a p-value<0.05. Morphological changes observed in erythrocytes include deformation and cell vacuolation. The maximum amount of changes in the morphology of erythrocytes occurs when black fish is exposed to 2 mg/L of PVC and 0.4 mg/L of paraquat (group I). The histological harm caused by the combination of PVC and paraquat is significant. Findings indicate that increasing the concentration of both microplastics and paraquat enhances their toxicity when combined. Consequently, it's imperative to assess the toxic impact of microplastics (MPs) and paraquat individually, as well as in combination, on aquatic organisms to safeguard them from the detrimental effects of these substances.

Impacts of nano- and micro-plastics exposure on zooplankton grazing, bacterial communities, and dimethylated sulfur compounds production in the microcosms

Dimethyl sulfide (DMS) is a prevalent volatile organic sulfur compound relevant to the global climate. Ecotoxicological effects of nano- and microplastics (NPs and MPs) on phytoplankton, zooplankton, and bacteria have been investigated by numerous studies. Yet, the influences of NPs/MPs on dimethylated sulfur compounds remains understudied. Herein, we investigated the impacts of polystyrene (PS) NPs/MPs (80 nm, 1 μm, and 10 μm) on zooplankton grazing, chlorophyll a (Chl a) concentration, bacterial community, dimethylsulfoniopropionate (DMSP), and DMS production in the microcosms. Our findings revealed that rotifer grazing increased the production of DMS in the absence of NPs/MPs but did not promote DMS production when exposed to NPs/MPs. The ingestion rates of the rotifer and copepod exposed to NPs/MPs at high concentrations were significantly reduced. NPs/MPs exposure significantly decreased DMS levels in the treatments with rotifers compared to the animal controls. In the bacterial microcosms, smaller NPs/MPs sizes were more detrimental to Chl a concentrations compared to larger sizes. The study revealed a stimulatory effect on Chl a concentrations, DMSPd concentrations, and bacterial abundances when exposed to 10 μm MP with low concentrations. The effects of NPs/MPs on DMS concentrations were both dose- and size-dependent, with NPs showing greater toxicity compared to larger MPs. NPs/MPs led to changes in bacterial community compositions, dependent on both dosage and size. NPs caused a notable decrease in the alpha diversities and richness of bacteria compared to MPs. These results provide insights into the influences of NPs/MPs on food webs, and subsequently organic sulfur compounds cycles.

Microplastics predominantly affect gut microbiota by altering community structure rather than richness and diversity: A meta-analysis of aquatic animals

The impacts of microplastics on the gut microbiota, a crucial component of the health of aquatic animals, remain inadequately understood. This phylogenetically controlled meta-analysis aims to identify general patterns of microplastic effects on the alpha diversity (richness and Shannon index), beta diversity, and community structure of gut microbiota in aquatic animals. Data from 63 peer-reviewed articles on the Web of Science were synthesized, encompassing 424 observations across 31 aquatic species. The analysis showed that microplastics significantly altered the community structure of gut microbiota, with between-group distances being 87.75% higher than within-group distances. This effect was significant even at environmentally relevant concentrations (≤1 mg L-1). However, their effects on richness, Shannon index, and beta diversity (community variation) were found to be insignificant. The study also indicated that the effects of microplastics were primarily dependent on their concentration and size, while the phylogeny of tested species explained limited heterogeneity. Furthermore, variations in gut microbiota alpha diversity, beta diversity, and community structure were correlated with changes in antioxidant enzyme activities from the liver and hepatopancreas. This implies that gut microbiota attributes of aquatic animals may provide insights into host antioxidant levels. In summary, this study illuminates the impacts of microplastics on the gut microbiota of aquatic animals and examines the implications of these effects for host health. It emphasizes that microplastics mainly alter the community structure of gut microbiota rather than significantly affecting richness and diversity.

The hidden threat: Unraveling the impact of microplastics on reproductive health

Microplastics, with intricate physical and chemical characteristics, infiltrate the food chain and extensively impact ecosystems. Despite acknowledging the link between environmental pollution and declining fertility, the specific mechanisms affecting reproductive health remain to be elucidated. This review emphasizes the global correlation between microplastics and subfertility, focusing on entry pathways and impacts on ecosystems. Research suggests that microplastics disrupt the neuroendocrine system, influencing sex hormone synthesis through the hypothalamic-pituitary-gonadal (HPG) axis. In the reproductive system, microplastics interfere with the blood-testis barrier, impairing spermatogenesis in males, and causing placental dysfunction, ovarian atrophy, endometrial hyperplasia, and fibrosis in females. Moreover, microplastics potentially affect offspring's lipid metabolism and reproductive functions. However, complex microplastic compositions and detection method limitations impede research progress. Mitigation strategies for reproductive effects, combined with addressing microplastic pollution through sustainable practices, are imperative. This review underscores the urgency of global initiatives and collaborative research to safeguard reproductive health amid escalating microplastic contamination.

The competition of heavy metals between hyporheic sediments and microplastics of driving factors in the Beiluo River Basin

Both sediments and microplastics (MPs) are medias of heavy metals (HMs) in river ecosystems. This study investigated HMs (Mn, Cr, V, As, Cu, Co, Cd, Pb, and Ni) concentration and driving factors for competitive enrichment between hyporheic sediments versus MPs. The medias basic characteristics indicated that the sediments were mostly sand and rich in Fe2O3; three polymer types were identified, with blue, fragment, less than 500 µm being the main types of MPs. The results have shown that the average content of extracted HMs in MPs was much higher than that of the same metals accumulated in sediments. HMs in sediments and MPs reached heavily polluted at some points, among which As and Cd were ecological risks. Electrostatic adsorption and surface complexation, and biofilm-mediated and organic matter complexation were the interaction mechanism of HMs with sediments and MPs. Further, the driving factors affecting the distribution of HMs in the two carriers were analyzed by multivariate statistical analysis. The results demonstrated that carrier characteristics, hydrochemical factors, and the inherent metal load of MPs were the main causes of the high HMs content. These findings improved our understanding of HMs fate and environmental risks across multiple medias.

Distribution and effects of microplastics as carriers of heavy metals in river surface sediments

There are few studies on microplastics (MPs) in urban river sediments compared to oceans, soils, and even rivers. In this study, the seasonal abundance of MPs, as well as their influencing factors on heavy metal adsorption in river sediments of the Ancient Canal of Zhenjiang City, China, were investigated for the first time. Through on-site sampling, microscopic observation, Raman spectroscopy, scanning electron microscopy, and high-temperature digestion, the abundance, shape, color, particle size, type, and surface characteristics of MPs in Ancient Canal sediments in different seasons, as well as the influencing factors of MPs as heavy metal carriers in different seasons, were analyzed. The results showed that the average abundance of MPs is 2049.09 ± 883.78 and 2216.36 ± 826.21 items kg-1 dry sediments in summer and winter, respectively, and different sites change significantly. In addition, particle sizes, types, colors, and shapes of MPs exhibited seasonal variations. Four MPs shapes were mainly observed: fibers, fragments, particles, and films. Among them, MPs in summer sediments are mainly fiber, and MPs in winter sediments are mainly particles. In the sediment in summer and winter, transparent MPs and small-size (<0.5 mm) MPs are the main ones, where the abundance of MPs decreased with increasing MPs size. The main MPs species are polyvinyl chloride (PVC), polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET), polycarbonate (PC), and polyethylene (PE), with PP being the predominant MPs in the sediments in different seasons. Scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) revealed that the surfaces of the MPs were characterized by rough, porous, cracked, and torn, with the attachment of various heavy metal elements, and all of the heavy metal elements accumulated to different degrees on the MPs. There was a significant positive correlation (p < 0.05) between the Mn content in the MPs and the Mn content in the sediments in winter, suggesting that the Mn in the MPs in winter may be derived from the sediments. In addition, the type, shape, size, and color of MPs affect the adsorption capacity of heavy metals. Most of the adsorption of MPs on Pb showed a significant negative correlation, and the adsorption of MPs on Cr, Zn, Cu, Cd, and Mn showed a significant positive correlation. MPs can be used as carriers of heavy metals, which will further enhance the hazards of living organisms and pose a potential threat to the safety of the urban river environment.

Effect of ultraviolet aged polytetrafluoroethylene microplastics on copper bioavailability and Microcystis aeruginosa growth

Microplastics (MPs) are ubiquitous in aquatic environments, which can act as carriers to affect the bioavailability of heavy metals. The aging process in the environment changes the physicochemical properties of MPs, thereby affecting their environmental behavior and co-toxicity with other pollutants. However, relevant research is limited. In this study, we compared the properties and Cu2+ adsorption capacity of pristine and aged polytetrafluoroethylene (PTFE) MPs and further explored the influence on copper bioavailability and bio-effects on Microcystis aeruginosa. Aging process induced surface oxidation and cracks of PTFE MPs, and decreased the stability of MPs in water by increasing zeta potential. PTFE MPs had a strong adsorption capacity for Cu2+ and increased the bioavailability of copper to microalgae, which was not affected by the aging process. Pristine and aged PTFE MPs adhered to cyanobacterium surfaces and caused shrinkage and deformation of cells. Inhibition of cyanobacterium growth, photosynthesis and reduction of total antioxidant capacity were observed in the treatment of PTFE MPs. Combined exposure of pristine MPs and Cu2+ had stronger toxic effects to cyanobacterium, and increased Microcystin-LR release, which could cause harm to aquatic environment. Aging reduced the toxic effects of PTFE MPs on microalgae. Furthermore, soluble exopolysaccharide (EPS) content was significantly higher in co-exposure of aged MPs and Cu2+, which could reduce the toxicity to cyanobacterium cells. These results indicate that aging process alleviates the toxicity to microalgae and environmental risks caused by PTFE MPs. This study improves understanding of the combined toxicity of aged MPs and metals in freshwater ecosystems.

Combined toxicity of polyvinyl chloride microplastics and copper to marine jacopever (Sebastes schlegelii)

Marine organisms commonly encounter co-stress resulting from the coexistence of microplastics (MPs) and heavy metals pollution in marine environments. Nevertheless, the combined effects and toxicity mechanisms of MPs and heavy metals on marine organisms remain unclear. This study integrated growth, physiological, morphological, and biochemical markers to assess the individual and combined toxicity of polyvinyl chloride MPs (PVC MPs, 1 × 104 particles/L) and copper (Cu, 200 μg/L) on marine jacopever (Sebastes schlegelii). The results revealed that co-exposure to MPs and Cu had a more detrimental impact on jacopever compared to the single-exposure groups, as evidenced by the enhanced growth inhibition, respiratory stress, and hepatotoxicity. This phenomenon may be attributed to PVC MPs accelerating the accumulation of Cu in jacopever liver. Therefore, peroxidation damage occurred in the co-exposed liver and may result in liver dysfunction. These findings contribute valuable insights into the risks associated with the coexistence of MPs and heavy metal pollution in marine ecosystems.

Subchronic co-exposure of polystyrene nanoplastics and 3-BHA significantly aggravated the reproductive toxicity of ovaries and uterus in female mice

Both nanoplastics (NPs) and 3-tert-butyl-4-hydroxyanisole (3-BHA) are environmental contaminants that can bio-accumulate through the food chain. However, the combined effects of which on mammalian female reproductive system remain unclear. Here, the female ICR-CD1 mice were used to evaluate the damage effects of ovaries and uterus after NPs and 3-BHA co-treatment for 35 days. Firstly, co-exposure significantly reduced the body weight and organ index of ovaries and uterus in mice. Secondly, combined effects of NPs and 3-BHA exacerbated the histopathological abnormalities to the ovaries and uterus and decreased female sex hormones such as FSH and LH while increased antioxidant activities including CAT and GSH-Px. Moreover, the apoptotic genes, inflammatory cytokines and the key reproductive development genes such as FSTL1 were significantly up-regulated under co-exposure conditions. Thirdly, through transcriptional and bioinformatics analysis, immunofluorescence and western blotting assays, together with molecular docking simulation, we determined that co-exposure up-regulated the FSTL1, TGF-β and p-Smad1/5/9 but down-regulated the expression of BMP4. Finally, the pharmacological rescue experiments further demonstrated that co-exposure of NPs and 3-BHA mainly exacerbated the female reproductive toxicity through FSTL1-mediated BMP4/TGF-β/SMAD signaling pathway. Taken together, our studies provided the theoretical basis of new environmental pollutants on the reproductive health in female mammals.

Microplastics and environmental effects: investigating the effects of microplastics on aquatic habitats and their impact on human health

Microplastics (MPs) are particles with a diameter of <5 mm. The disposal of plastic waste into the environment poses a significant and pressing issue concern globally. Growing worry has been expressed in recent years over the impact of MPs on both human health and the entire natural ecosystem. MPs impact the feeding and digestive capabilities of marine organisms, as well as hinder the development of plant roots and leaves. Numerous studies have shown that the majority of individuals consume substantial quantities of MPs either through their dietary intake or by inhaling them. MPs have been identified in various human biological samples, such as lungs, stool, placenta, sputum, breast milk, liver, and blood. MPs can cause various illnesses in humans, depending on how they enter the body. Healthy and sustainable ecosystems depend on the proper functioning of microbiota, however, MPs disrupt the balance of microbiota. Also, due to their high surface area compared to their volume and chemical characteristics, MPs act as pollutant absorbers in different environments. Multiple policies and initiatives exist at both the domestic and global levels to mitigate pollution caused by MPs. Various techniques are currently employed to remove MPs, such as biodegradation, filtration systems, incineration, landfill disposal, and recycling, among others. In this review, we will discuss the sources and types of MPs, the presence of MPs in different environments and food, the impact of MPs on human health and microbiota, mechanisms of pollutant adsorption on MPs, and the methods of removing MPs with algae and microbes.

Microplastics pollution in the Surma River, Bangladesh: A rising hazard to upstream water quality and aquatic life

The ecological health of freshwater rivers is deteriorating globally due to careless human activities, for instance, the emission of plastic garbage into the river. The current research was the first assessment of microplastics (MPs) pollution in water, sediment, and representative organisms (fish, crustacean, and bivalve) from the Surma River. Water, sediment, and organisms were sampled from six river sites (Site 1: Charkhai; Site 2: Golapganj; Site 3: Alampur; Site 4: Kazir Bazar; Site 5: Kanishail and Site 6: Lamakazi), and major water quality parameters were recorded during sampling. Thereafter, MPs in water, sediment, and organism samples were extracted, and then microscopically examined to categorize selected MPs types. The abundance of MPs, as well as size, and color distribution, were estimated. Polymer types were analyzed by ATR-FTIR, the color loss of MPs was recorded, the Pollution Load Index (PLI) was calculated, and the relationship between MPs and water quality parameters was analyzed. Sites 4 and 5 had comparatively poorer water quality than other sites. Microplastic fibers, fragments, and microbeads were consistently observed in water, sediment, and organisms. A substantial range of MPs in water, sediment, and organisms (37.33-686.67 items/L, 0.89-15.12 items/g, and 0.66-48.93 items/g, respectively) was recorded. There was a diverse color range, and MPs of <200 μm were prevalent in sampling areas. Six polymer types were identified by ATR-FTIR, namely Polyethylene (PE), Polyamide (PA), Polypropylene (PP), Cellulose acetate (CA), Polyethylene terephthalate (PET), and Polystyrene (PS), where PE (41%) was recognized as highly abundant. The highest PLI was documented in Site 4 followed by Site 5 both in water and sediment. Likewise, Sites 4 and 5 were substantially different from other study areas according to PCA. Overall, the pervasiveness of MPs was evident in the Surma River, which requires further attention and prompt actions.

A Pretty Kettle of Fish: A Review on the Current Challenges in Mediterranean Teleost Reproduction

The Mediterranean region is facing several environmental changes and pollution issues. Teleosts are particularly sensitive to these challenges due to their intricate reproductive biology and reliance on specific environmental cues for successful reproduction. Wild populations struggle with the triad of climate change, environmental contamination, and overfishing, which can deeply affect reproductive success and population dynamics. In farmed species, abiotic factors affecting reproduction are easier to control, whereas finding alternatives to conventional diets for farmed teleosts is crucial for enhancing broodstock health, reproductive success, and the sustainability of the aquaculture sector. Addressing these challenges involves ongoing research into formulating specialized diets, optimizing feeding strategies, and developing alternative and sustainable feed ingredients. To achieve a deeper comprehension of these challenges, studies employing model species have emerged as pivotal tools. These models offer advantages in understanding reproductive mechanisms due to their well-defined physiology, genetic tractability, and ease of manipulation. Yet, while providing invaluable insights, their applicability to diverse species remains constrained by inherent variations across taxa and oversimplification of complex environmental interactions, thus limiting the extrapolation of the scientific findings. Bridging these gaps necessitates multidisciplinary approaches, emphasizing conservation efforts for wild species and tailored nutritional strategies for aquaculture, thereby fostering sustainable teleost reproduction in the Mediterranean.

Recent advance of nanomaterials modified electrochemical sensors in the detection of heavy metal ions in food and water

As one of the main pollutants, heavy metal ions can accumulate in the human body and cause a cascade of damage. Electrochemical sensors provide great prospects for tracing heavy metal ions because of their properties of high sensitivity, low detection limits and fast response. Electrode surface modification materials play a key role in enhancing the performance of electrochemical sensors. Herein, we summarize in detail the recent work on electrochemical sensors modified by carbon nanomaterials (graphene and its derivatives, carbon nanofibers and carbon nanotubes), metal nanomaterials (gold, silver, bismuth and iron), complexes (MOFs, ZIFs and MXenes) and their composites for the detection of heavy metal ions (mainly include Cd(II), Hg(II), Pb(II), As(III), Cu(II) and Zn(II)) in food and water. The synthetic strategies, mechanisms, innovations, advantages, challenges and prospects of various electrode modification nanomaterials for the detection of heavy metal ions in food and water are discussed.

Combined toxic effects of polyethylene microplastics and lambda-cyhalothrin on gut of zebrafish (Danio rerio)

Microplastics (MPs), which are prevalent and increasingly accumulating in aquatic environments. Other pollutants coexist with MPs in the water, such as pesticides, and may be carried or transferred to aquatic organisms, posing unpredictable ecological risks. This study sought to assess the adsorption of lambda-cyhalothrin (LCT) by virgin and aged polyethylene MPs (VPE and APE, respectively), and to examine their influence on LCT's toxicity in zebrafish, specifically regarding acute toxicity, oxidative stress, gut microbiota and immunity. The adsorption results showed that VPE and APE could adsorb LCT, with adsorption capacities of 34.4 mg∙g-1 and 39.0 mg∙g-1, respectively. Compared with LCT exposure alone, VPE and APE increased the acute toxicity of LCT to zebrafish. Additionally, exposure to LCT and PE-MPs alone can induce oxidative stress in the zebrafish gut, while combined exposure can exacerbate the oxidative stress response and intensify intestinal lipid peroxidation. Moreover, exposure to LCT or PE-MPs alone promotes inflammation, and combined exposure leads to downregulation of the myd88-nf-κb related gene expression, thus impacting intestinal immunity. Furthermore, exposure to APE increased LCT toxicity to zebrafish more than VPE. Meanwhile, exposure to PE-MPs and LCT alone or in combination has the potential to affect gut microbiota function and alter the abundance and diversity of the zebrafish gut flora. Collectively, the presence of PE-MPs may affect the toxicity of pesticides in zebrafish. The findings emphasize the importance of studying the interaction between MPs and pesticides in the aquatic environment.

Liver Injury Induced by Exposure to Polystyrene Microplastics Alone or in Combination with Cadmium in Mice Is Mediated by Oxidative Stress and Apoptosis

Microplastics (MPs) have been considered an emerging environmental pollutant which, when combined with toxic metals, enter the circulatory system of mammals and eventually cause damage. Therefore, it is important to study the toxicity of the mixture of MPs and heavy metals for evaluating risk assessment of mammals. In the present study, the toxicological effects of different concentrations of polystyrene (PS)-MPs alone or in combination with cadmium chloride (CdCl2) during chronic exposure (8 weeks) were evaluated using intragastric administration in mice. Using comparative analysis, it was revealed that PS-MPs alone or in combination with Cd could destroy the normal structural morphology of liver tissue and increase the levels of two biochemical indicators of liver damage, thereby inducing changes in antioxidant and hyperoxide capacities. In addition, PS-MPs and/or Cd activated the antioxidant signaling pathway Nrf2-Keap1 and affected the endogenous apoptosis signaling pathway p53-Bcl-2/Bax, thus promoting apoptosis. These findings suggested that exposure to MPs alone or in combination with Cd led to adverse effects on the liver. Furthermore, it was revealed that co-exposure to MPs and Cd reduced Cd toxicity, thereby highlighting the possibility MPs may act as carriers of other toxic substances and coordinate with them. Therefore, evaluating the synergistic or anti-agonistic effects of MPs on the toxicity and bioavailability of xenobiotics is in the future critical in environmental toxicological studies.

Polystyrene nanoplastic and engine oil synergistically intensify toxicity in Nile tilapia, Oreochromis niloticus : Polystyrene nanoplastic and engine oil toxicity in Nile tilapia

Polystyrene nanoplastic (PS-NPs) and Engine oil (EO) pose multiple ecotoxic effects with increasing threat to fish ecosystems. The current study investigated the toxicity of 15 days exposure to PS-NPs and / or EO to explore their combined synergistic effects on Nile tilapia, Oreochromis niloticus (O. niloticus). Hematobiochemical parameters, proinflammatory cytokines, and oxidative stress biomarkers as well as histological alterations were evaluated. The experimental design contained 120 acclimated Nile tilapia distributed into four groups, control, PS-NPs (5 mg/L), EO (1%) and their combination (PS-NPs + EO). After 15-days of exposure, blood and tissue samples were collected from all fish experimental groups. Results indicated that Nile tilapia exposed to PS-NPs and / or EO revealed a significant decrease in almost all the measured hematological parameters in comparison to the control, whereas WBCs and lymphocyte counts were significantly increased in the combined group only. Results clarified that the combined PS-NPs + EO group showed the maximum decrease in RBCs, Hb, MCH and MCHC, and showed the maximum significant rise in interleukin-1β (IL-1β), and interleukin-6 (IL-6) in comparison to all other exposed groups. Meanwhile, total antioxidant capacity (TAC) showed a significant (p < 0.05) decline only in the combination group, whereas reduced glutathione (GSH) showed a significant decline in all exposed groups in comparison to the control. Both malondialdehyde (MDA) and aspartate aminotransferase (AST) showed a significant elevation only in the combination group. Uric acid showed the maximum elevation in the combination group than all other groups, whereas creatinine showed significant elevation in the EO and combination group when compared to the control. Furthermore, the present experiment proved that exposure to these toxicants either individually or in combination is accompanied by pronounced histomorpholgical damage characterized by severe necrosis and hemorrhage of the vital organs of Nile tilapia, additionally extensively inflammatory conditions with leucocytes infiltration. We concluded that combination exposure to both PS-NPs and EO caused severe anemia, extreme inflammatory response, oxidative stress, and lipid peroxidation effects, thus they can synergize with each other to intensify toxicity in fish.

Effects of single and combined exposure of virgin or aged polyethylene microplastics and penthiopyrad on zebrafish (Danio rerio)

The interaction between pesticides and microplastics (MPs) can lead to changes in their mode of action and biological toxicity, creating substantial uncertainty in risk assessments. Succinate dehydrogenase inhibitor (SDHI) fungicides, a common fungicide type, are widely used. However, little is known about how penthiopyrad (PTH), a member of the SDHI fungicide group, interacts with polyethylene microplastics (PE-MPs). This study primarily investigates the individual and combined effects of virgin or aged PE-MPs and penthiopyrad on zebrafish (Danio rerio), including acute toxicity, bioaccumulation, tissue pathology, enzyme activities, gut microbiota, and gene expression. Short-term exposure revealed that PE-MPs enhance the acute toxicity of penthiopyrad. Long-term exposure demonstrated that PE-MPs, to some extent, enhance the accumulation of penthiopyrad in zebrafish, leading to increased oxidative stress injury in their intestines by the 7th day. Furthermore, exposure to penthiopyrad and/or PE-MPs did not result in histopathological damage to intestinal tissue but altered the gut flora at the phylum level. Regarding gene transcription, penthiopyrad exposure significantly modified the expression of pro-inflammatory genes in the zebrafish gut, with these effects being mitigated when VPE or APE was introduced. These findings offer a novel perspective on environmental behavior and underscore the importance of assessing the combined toxicity of PE-MPs and fungicides on organisms.

Microplastics inhibit the growth of endosymbiotic Symbiodinium tridacnidorum by altering photosynthesis and bacterial community

Microplastics, ubiquitous anthropogenic marine pollutants, represent potential threats to coral-Symbiodiniaceae relationships in global reef ecosystems. However, the mechanism underlying the impacts of polystyrene microplastics (PS-MPs) on Symbiodiniaceae remains poorly understood. In this study, the cytological, physiological, and microbial responses of Symbiodinium tridacnidorum, a representative Symbiodiniaceae species, to varying concentrations of PS-MPs (0, 5, 50, 100, and 200 mg L-1) were investigated. The results revealed that microplastic exposure inhibited cell division, resulting in reduced cell density compared to control group. Furthermore, algal photosynthetic activity, as indicated by chlorophyll content, Fv/Fm, and net photosynthetic rate, declined with increasing microplastic concentration up to 50 mg L-1. Notably, elevated levels of microplastics (100 and 200 mg L-1) prompted a significant increase in cell size in S. tridacnidorum. Transmission electron microscopy and fluorescence microscopy indicated that hetero-aggregation was formed between high levels of PS-MPs and algal cells, ultimately causing damage to S. tridacnidorum. Moreover, the impact of PS-MPs exposure on the bacterial community associated with S. tridacnidorum was investigated. The results showed a reduction in alpha diversity of the bacterial community in groups exposed to 50, 100, and 200 mg L-1 of microplastics compared to those treated with 0 and 5 mg L-1. Additionally, the relative abundance of Marinobacter, Marivita, and Filomicrobium significantly increased, while Algiphilus and norank Nannocystaceae declined after microplastic exposure. These findings suggest that MPs can inhibit the growth of S. tridacnidorum and alter the associated bacterial community, posing a potential serious threat to coral symbiosis involving S. tridacnidorum.

Polystyrene microplastics mitigate lead-induced neurotoxicity by reducing heavy metal uptake in zebrafish larvae

The combined pollution of lead (Pb) and polystyrene microplastics (PS-MPs) is common in aquatic environments. However, the combined neurotoxicity of these two pollutants is still poorly understood. In this study, zebrafish (Danio rerio) larvae were used to assess the combined neurotoxicity and mechanism of Pb and PS-MPs at environmentally relevant concentrations. The results showed that Pb (10 μg/L) induced abnormal behavior including significantly reduced movement distance, maximum acceleration, and average velocity (P < 0.05) along with altered expression of neurodevelopment-related genes (gap43 and α1-tubulin) (P < 0.05). PS-MPs (25 μg/L, 250 μg/L; diameter at 25 μm) co-exposure not only significantly reduced the concentration of Pb in the exposed solution (P < 0.01), but also decreased the uptake of Pb by downregulating the divalent metal transporter 1 gene (dmt1) (P < 0.01), thereby alleviating Pb-induced neurotoxicity. However, to demonstrate that PS-MPs alleviate the neurotoxicity of Pb by reducing Pb uptake, upregulation of dmt1 by addition of deferoxamine (DFO, an efficient iron chelator, 100 μM) significantly increased the Pb uptake and exacerbated neurotoxicity in zebrafish. In summary, our results demonstrated that PS-MPs alleviate Pb neurotoxicity by downregulating the mRNA level of dmt1 and decreasing the Pb uptake. This study provides a new insight into the combined neurotoxicity and underlying mechanisms of PS-MPs and Pb on zebrafish.

Co-exposure with cadmium elevates the toxicity of microplastics: Trojan horse effect from the perspective of intestinal barrier

Microplastics (MPs) have been shown to adsorb heavy metals and serve as vehicles for their environmental transport. To date, insufficient studies have focused on enterohepatic injury in mice co-exposed to both MPs and cadmium (Cd). Here, we report that Cd adsorption increased the surface roughness and decreased the monodispersity of PS-MPs. Furthermore, exposure to both PS-MPs and Cd resulted in a more severe toxic effect compared to single exposure, with decreased body weight gain, shortened colon length, and increased colonic and hepatic inflammatory response observed. This can be attributed to an elevated accumulation of Cd resulting from increased gut permeability, coupled with the superimposed effects of oxidative stress. In addition, using 16 S sequencing and fecal microbiota transplantation, it was demonstrated that gut microbiota dysbiosis plays an essential role in the synergistic toxicity induced by PS-MPs and Cd in mice. This study showed that combined exposure to MPs and Cd induced more severe intestinal and liver damage in mice compared to individual exposure, and provided a new perspective for a more systematic risk assessment process related to MPs exposure.

The effect and mechanism of variable particle size microplastics and levofloxacin on the neurotoxicity of Rana nigromaculata based on the microorganism-intestine-brain axis

Microplastics (MPs) usually appear in the aquatic environment as complex pollutants in combination with other environmental pollutants, such as levofloxacin (LVFX). After a 45-day exposure to LVFX and MPs with different particle sizes at environmental levels, LVFX was neurotoxic to Rana nigromaculata tadpoles. The order of the effects of the exposure treatment on tadpole behavior was: LVFX-MP3>LVFX-MP1>LVFX-MP2 ≥ LVFX. Results of transcriptome analysis of tadpole brain tissue showed that LVFX in combination with 0.10 and 10.00 μm MP interferes with the nervous system through the cell adhesion molecules pathway. Interestingly, the order of effects of the co-exposure on oxidative stress in the intestine was inconsistent with that of tadpole behavior. We found that Paraacteroides might be a microplastic indicator species for the gut microbiota of aquatic organisms. The results of the targeted metabolism of neurotransmitters in the intestine suggest that in the LVFX-MP2 treatment, LVFX alleviated the intestinal microbiota disorder caused by 1.00 μm MP, by regulating intestinal microbiota participating in the TCA cycle VI and gluconeogenesis and tetrapyrrole biosynthesis I, while downregulating Met and Orn, and upregulating 5HIAA, thereby easing the neurotoxicity to tadpoles exposed to LVFX-MP2. This work is of great significance for the comprehensive assessment of the aquatic ecological risks of microplastics-antibiotic compound pollutants.

Copper exposure causes alteration in the intestinal microbiota and metabolites in Takifugu rubripes

Copper is an environmental pollutant, and copper in aquatic environments mainly comes from soil and water. It enters the environment through atmospheric deposition, sewage discharge, and industrial production, and enters aquatic organisms, causing toxicity. Takifugu rubripes (T. rubripes) is a marine fish with high economic value. Due to the toxic effects of heavy metals on aquatic organisms such as fish, it can affect the gut community and metabolites of fish. The gut is an important channel for fish to communicate with the outside world and a necessary pathway for the metabolism of nutrients and toxic substances in the fish body. Studies have shown that due to changes in global water emissions and the high sensitivity of aquatic organisms to the environment, copper may pose greater potential hazards to aquatic organisms. Copper poses a greater risk to aquatic species than other heavy metals and metal/metal like pollutants (such as cadmium, lead, mercury, arsenic, etc.) . In order to elucidate the effects of copper exposure on the gut of T. rubripes. In this study, we exposed T. rubripes to 0, 50, 100, or 500 μg/L of copper for three days, the effects of copper exposure on the gut microbiota structure and metabolites of the T. rubripes were investigated using 16 S rRNA gene and metabolomics techniques. The research results indicate that with the increase copper concentration, the intestinal tissue of T. rubripes undergoes significant damage. 16 S rRNA sequencing results show that copper exposure alters the structure and metabolites of intestinal microbiota. Copper exposure of 100 and 500 μg/L inhibited the colonization of the bacterial gut, disrupted the intestinal barrier, and made the fish susceptible to the pathogens. Liquid chromatography-mass spectrometry analysis showed that copper regulated the production of metabolites such as L-histidine, arachidonic acid, and L-glutamic acid, which are related to energy and immunity. Microbiome-metabolome correlation analysis showed that Subdoligranulum, Family_XIII_AD3011_group, and Clostridium_sensu_stricto_1 were the key bacteria for copper ion intervention, and they might up-regulate the levels of metabolites such as indole-3-acetic acid, 3-indoleacrylic acid, and 5-hydroxyindole in the tryptophan metabolism pathway. In summary, our research has demonstrated that copper exposure can cause pathological changes in the intestinal tissue of the T. rubripes. High concentrations of copper ions can affect the colonization of the T. rubripes microbiota in the intestine, damage the fish's immune system, and alter the structure and metabolites of the intestinal microbiota, this can lead to intestinal metabolic dysfunction. providing a reference for the evaluation of the biological toxicity effects of heavy metal elements in the marine environment. This study provides a reference for evaluating the biological toxicity effects of heavy metal elements in marine environments.

Long-term tralopyril exposure results in endocrinological and transgenerational toxicity: A two-generation study of marine medaka (Oryzias melastigma)

This study aims to investigate the impact of tralopyril, a newly developed marine antifouling agent, on the reproductive endocrine system and developmental toxicity of offspring in marine medaka. The results revealed that exposure to tralopyril (0, 1, 20 μg/L) for 42 days resulted in decreased reproductive capacity in marine medaka. Moreover, it disrupted the levels of sex hormones E2 and T, as well as the transcription levels of genes related to the HPG axis, such as cyp19b and star. Sex-dependent differences were observed, with females experiencing more pronounced effects. Furthermore, intergenerational toxicity was observed in F1 offspring, including increased heart rate, changes in retinal morphology and cartilage structure, decreased swimming activity, and downregulation of transcription levels of relevant genes (HPT axis, GH/IGF axis, cox, bmp4, bmp2, runx2, etc.). Notably, the disruption of the F1 endocrine system by tralopyril persisted into adulthood, indicating a transgenerational effect. Molecular docking analysis suggested that tralopyril's RA receptor activity might be one of the key factors contributing to the developmental toxicity observed in offspring. Overall, our study highlights the potential threat posed by tralopyril to the sustainability of fish populations, as it can disrupt the endocrine system and negatively impact aquatic organisms for multiple generations.

Microplastics as carriers of toxic pollutants: Source, transport, and toxicological effects

Microplastic pollution has emerged as a new environmental concern due to our reliance on plastic. Recent years have seen an upward trend in scholarly interest in the topic of microplastics carrying contaminants; however, the available review studies have largely focused on specific aspects of this issue, such as sorption, transport, and toxicological effects. Consequently, this review synthesizes the state-of-the-art knowledge on these topics by presenting key findings to guide better policy action toward microplastic management. Microplastics have been reported to absorb pollutants such as persistent organic pollutants, heavy metals, and antibiotics, leading to their bioaccumulation in marine and terrestrial ecosystems. Hydrophobic interactions are found to be the predominant sorption mechanism, especially for organic pollutants, although electrostatic forces, van der Waals forces, hydrogen bonding, and pi-pi interactions are also noteworthy. This review reveals that physicochemical properties of microplastics, such as size, structure, and functional groups, and environmental compartment properties, such as pH, temperature, and salinity, influence the sorption of pollutants by microplastic. It has been found that microplastics influence the growth and metabolism of organisms. Inadequate methods for collection and analysis of environmental samples, lack of replication of real-world settings in laboratories, and a lack of understanding of the sorption mechanism and toxicity of microplastics impede current microplastic research. Therefore, future research should focus on filling in these knowledge gaps.

Effects of elevated temperature and different crystal structures of TiO2 nanoparticles on the gut microbiota of mussel Mytilus coruscus

Coastal habitats are exposed to increasing pressure of nanopollutants commonly combined with warming due to the seasonal temperature cycles and global climate change. To investigate the toxicological effects of TiO2 nanoparticles (TiO2 NPs) and elevated temperature on the intestinal health of the mussels (Mytilus coruscus), the mussels were exposed to 0.1 mg/L TiO2 NPs with different crystal structures for 14 days at 20 °C and 28 °C, respectively. Compared to 20 °C, the agglomeration of TiO2 NPs was more serious at 28 °C. Exposure to TiO2 NPs led to elevated mortality of M. coruscus and modified the intestinal microbial community as shown by 16S rRNA sequence analysis. Exposure to TiO2 NPs changed the relative abundance of Bacteroidetes, Proteobacteria and Firmicutes. The relative abundances of putative mutualistic symbionts Tenericutes and Fusobacteria increased in the gut of M. coruscus exposed to anatase, which have contributed to the lower mortality in this group. LEfSe showed the combined stress of warming and TiO2 NPs increased the risk of M. coruscus being infected with potential pathogenic bacteria. This study emphasizes the toxicity differences between crystal structures of TiO2 NPs, and will provides an important reference for analyzing the physiological and ecological effects of nanomaterial pollution on bivalves under the background of global climate change.

Transgenerational effects of microplastics on Nrf2 signaling, GH/IGF, and HPI axis in marine medaka Oryzias melastigma under different salinities

Little information is available on the toxicity of microplastics (MPs) under different salinities in aquatic organisms. Consequently, the effects of larvae exposure to 180 μg/L MPs with 5.0 μm diameter on growth, antioxidant capacity and stress response were investigated in exposed F1 larvae and unexposed F2 larvae in marine medaka Oryzias melastigma at 5 ‰ and 25 ‰ salinities. Poor growth performance of F1 and F2 larvae and F1 adult fish was merely found under high salinity, as well as changes in the growth hormone/insulin-like growth factor-I (GH/IGF). Although malondialdehyde (MDA) content and antioxidant capacity remained constant in F1 larvae under high salinity, MPs increased MDA content and reduced antioxidant capacity in F2 larvae. Contrarily, MDA and antioxidant capacity increased in F1 and F2 larvae under low salinity. The mRNA expression levels of genes in the NF-E2-related factor 2 (Nrf2) pathway were dysregulated. Cortisol levels in the whole body increased in F1 larvae and recovered to the control level under low salinity while cortisol levels declined in F1 larvae and increased in F2 larvae under high salinity, which was related to the transcriptional regulation of the hypothalamus-pituitary-interrenal (HPI) axis genes. To summary, the present study determined the toxic effects of MPs on growth, antioxidant capacity, and stress response by disturbing Nrf2, HPI, and GH/IGF signaling in exposed larvae and unexposed offspring of marine medaka in a salinity-dependent manner. For the first time, our results highlight the interference effects of salinity on MPs toxicity in fish.

The invisible Threat: Assessing the reproductive and transgenerational impacts of micro- and nanoplastics on fish

Micro- and nanoplastics (MNPs), emerging as pervasive environmental pollutants, present multifaceted threats to diverse ecosystems. This review critically examines the ability of MNPs to traverse biological barriers in fish, leading to their accumulation in gonadal tissues and subsequent reproductive toxicity. A focal concern is the potential transgenerational harm, where offspring not directly exposed to MNPs exhibit toxic effects. Characterized by extensive specific surface areas and marked surface hydrophobicity, MNPs readily adsorb and concentrate other environmental contaminants, potentially intensifying reproductive and transgenerational toxicity. This comprehensive analysis aims to provide profound insights into the repercussions of MNPs on fish reproductive health and progeny, highlighting the intricate interplay between MNPs and other pollutants. We delve into the mechanisms of MNPs-induced reproductive toxicity, including gonadal histopathologic alterations, oxidative stress, and disruptions in the hypothalamic-pituitary-gonadal axis. The review also underscores the urgency for future research to explore the size-specific toxic dynamics of MNPs and the long-term implications of chronic exposure. Understanding these aspects is crucial for assessing the ecological risks posed by MNPs and formulating strategies to safeguard aquatic life.

Gut microbiota related response of Oryzias melastigma to combined exposure of polystyrene microplastics and tetracycline

The co-existence of microplastics (MPs) and antibiotics in the coastal environment poses a combined ecological risk. Single toxic effects of MPs or antibiotics on aquatic organisms have been verified, however, the exploration of their combined toxic effects remains limited. Here, foodborne polystyrene microplastics (PS-MPs, 10 μm, 0.1 % w/w in food) and waterborne tetracyclines (TC, 50 μg/L) were used to expose an estuarine fish Oryzias melastigma for four weeks. We found that the aqueous availability of TC was not significantly altered coexisting with MPs. The fish body weight gain was significantly slower in TC alone or combined groups than the control group, consistent with the lower lipid content in livers. The body length gain was significantly inhibited by the combined presence compared to the single exposure. Both exposures led to a shift of gut microbiota composition and diversity. TC and the combined group possessed similar gut microbiota which is distinct from PS-MPs and the control group. The Firmicutes/Bacteroidetes (F/B) ratio in the TC and combined groups were significantly lower compared to the control, while the PS-MPs group showed no significant impact. Metabolomic analysis of the fish liver confirmed the shift of metabolites in specific pathways after different exposures. More, a number of gut microbiota-related metabolites on lipid metabolism was perturbed, which were annotated in arachidonic acid metabolism and linoleic acid metabolism. In all, TC modulates bacterial composition in the fish gut and disturbs their liver metabolites via the gut-liver axis, which led to the slower growth of O. melastigma. More, the adverse impact was aggravated by the co-exposure to foodborne PS-MPs.

The interfacial interaction between Dechlorane Plus (DP) and polystyrene nanoplastics (PSNPs): An overlooked influence factor for the algal toxicity of PSNPs

As pollution has attracted attention due to its wide distribution. An environmental concern that may be overlooked is that NPs additives are easily released into the environment due to their physical combination with NPs. However, the knowledge gaps still exist about the interfacial reactions of NPs and the additives (e.g. flame retardants) and the joint ecological effect. In the present study, fourier transform infrared (FTIR) spectrometer coupled with 2D correlation spectroscopy (2D-COS) analysis revealed the interfacial reactions between polystyrene nanoplastics (PSNPs) and Dechlorane Plus (DP). Results showed that carbon‑oxygen bonds and carbon‑chlorine bonds were the important binding sites during adhesion and DP could reduce the colloidal stability. Single and joint ecological effects of PSNPs and DP on the microalgae Chlorella vulgaris were further deliberated. Reduced photosynthetic efficiency (reduced Fv/Fm by 0.03 %), higher growth inhibition (16.15 %) and oxidative damage (increased ROS by 152 %) were observed in algae under co-exposure. Notably, DP could significantly increase the attachment of PSNPs to the surface of the algae. Metabolomics further revealed that co-exposure significantly down-regulated amino acid metabolism and tricarboxylic acid cycle (TCA) cycle, and up-regulated fatty acid metabolism. The present study provides new insights into the risk assessment of NPs in aquatic environment by investigating the interfacial reaction mechanism and combined ecotoxicity of NPs and additives.

Environmental relevant concentrations of polystyrene nanoplastics and lead co-exposure triggered cellular cytotoxicity responses and underlying mechanisms in Eisenia fetida

Heavy metal pollution of soils and the widespread use of plastics have caused environmental problems worldwide. Nanoplastics (NPs) contaminants in water and soil environments can adsorb heavy metals, thereby affecting the bioavailability and toxicity of heavy metals. In this paper, the effect of co-exposure of polystyrene microspheres with 100 nm particle size and lead acetate (Pb) on the Eisenia fetida coelomocytes was investigated. The environmental concentration of NPs used was 0.01 mg/L and the concentration of Pb ranged from 0.01 to 1 mg/L, and the exposed cells were incubated at 298 k for 24 h. Our study demonstrated that exposure of cells to environmental relevant concentrations of NPs did not significantly affect the cytotoxicity of Pb exposure. It was shown that co-exposure induced cellular production of reactive oxygen species (ROS, increased to 134.4 %) disrupted the antioxidant system of earthworm body cavity cells, activated superoxide dismutase and catalase (CAT), produced reduced glutathione, and inhibited glutathione-dependent enzyme (GST) activity (Reduced to 64 %). Total antioxidant capacity (T-AOC) is first enhanced against ROS due to the stress of NPs and Pb. When the antioxidant reserves of cells are exhausted, the antioxidant capacity will decrease. The level of malondialdehyde, a biomarker of eventual lipid peroxidation, increased to 231.7 %. At the molecular level, due to co-exposure to NPs and Pb, CAT was loosely structured and the secondary structure is misfolded, which was responsible for exacerbating oxidative damage in E. fetida coelomocytes. The findings of this study have significant implications for the toxicological interaction and future risk assessment of co-contamination of NPs and Pb in the environment.

Influence of heavy metal exposure on gut microbiota: Recent advances

Gut microbiota plays a functionally important part in retaining the homeostasis of host physiology, however, under exposure of various heavy metals, the composition of gut biota is disturbed in relation to species diversity and richness. Ever since the increase of microbiome-related studies during the last decade, many research studies have delivered an understanding of the reasons and concerns of gut microbiota-related modifications. During the past decade, it's been confirmed from various studies that heavy metals poisoning alters the microbial composition, which results in changes in gene expression, alteration in metabolism, immunity, neurological dysfunction, and causes various other disorders. The present comprehensive review is summarizing an attempt to enumerate the key findings from recent clinical or preclinical studies related to the influence of heavy metals on gut microbiota published recently. Google, PubMed, Science Direct, Scopus, and Google Scholar were employed as primary search engines using the keywords such as "heavy metals, gut microbiota, dysbiosis, and intestinal microbiota" for finding relevant research articles from the past 10 years and some old important articles. Here, we tried to provide insight into some of the key timelines and scientific findings from reported literature, like the effects of heavy metals such as arsenic, cadmium, lead, and mercury on the general body and specifically on the gut microbiota of different model organisms. So, it is important to increase awareness against heavy metal-induced toxicity and formulate guidelines for the benefit of the environment.

The Association Between Microplastics and Microbiota in Placentas and Meconium: The First Evidence in Humans

Pregnancy and infancy are vulnerable times for detrimental environmental exposures. However, the exposure situation of microplastics (MPs) for mother-infant pairs and the adverse health effect of MPs are largely unknown. Therefore, we explored MP exposure in placentas and meconium samples, and the potential correlation of MP exposure with microbiota in placentas and meconium. A total of 18 mother-infant pairs were effectively recruited from Shanghai, China. The study required pregnant women to provide placentas and meconium samples. An Agilent 8700 laser infrared imaging spectrometer (LDIR) was applied to identify MPs. Microbiota detection was identified by 16S rRNA sequencing. Sixteen types of MPs were found in all matrices, and polyamide (PA) and polyurethane (PU) were the major types we identified. MPs detected in samples with a size of 20-50 μm were more than 76.46%. At the phylum level, both placenta and meconium microbiota were mainly composed of Proteobacteria, Bacteroidota, and Firmicutes. We also found some significant differences between placenta and meconium microbiota in β-diversity and gut composition. Additionally, we found polystyrene was inversely related with the Chao index of meconium microbiota. Polyethylene was consistently inversely correlated with several genera of placenta microbiota. The total MPs, PA, and PU consistently impacted several genera of meconium microbiota. In conclusion, MPs are ubiquitous in placentas and meconium samples, indicating the wide exposure of pregnant women and infants. Moreover, our findings may support a link between high concentration of MPs and microbiota genera in placentas and meconium. Additionally, there were several significant associations between the particle size of MPs in 50-100 μm and meconium microbiota.

Co-exposure of microplastics and heavy metals in the marine environment and remediation techniques: a comprehensive review

Microplastics (MPs) and heavy metals are significant pollutants in the marine environment, necessitating effective remediation strategies to prevent their release into the sea through sewage and industrial effluent. This comprehensive review explores the current understanding of the co-exposure of MPs and heavy metal-enriched MPs, highlighting the need for effective remediation methods. Various mechanisms, including surface ion complexation, hydrogen bonding, and electrostatic forces, contribute to the adsorption of heavy metals onto MPs, with factors like surface area and environmental exposure duration playing crucial roles. Additionally, biofilm formation on MPs alters their chemical properties, influencing metal adsorption behaviors. Different thermodynamic models are used to explain the adsorption mechanisms of heavy metals on MPs. The adsorption process is influenced by various factors, including the morphological characteristics of MPs, their adsorption capacity, and environmental conditions. Additionally, the desorption of heavy metals from MPs has implications for their bioavailability and poses risks to marine organisms, emphasizing the importance of source reduction and remedial measures. Hybrid approaches that combine both conventional and modern technologies show promise for the efficient removal of MPs and heavy metals from marine environments. This review identifies critical gaps in existing research that should be addressed in future studies including standardized sampling methods to ensure accurate data, further investigation into the specific interactions between MPs and metals, and the development of hybrid technologies at an industrial scale. Overall, this review sheds light on the adsorption and desorption mechanisms of heavy metal-enriched MPs, underscoring the necessity of implementing effective remediation strategies.

Toxicity of co-exposure of microplastics and lead in African catfish (Clarias gariepinus)

Microplastics (MPs) are an emerging threat to freshwater ecosystems with several ecotoxicological ramifications for fish. Microplastics (MPs) can adsorb heavy metals on their surfaces and increase their availability to aquatic organisms. The combined impact of lead and microplastics on fish has only been studied seldom utilizing a variety of markers. The present study aimed to evaluate the hematological, biochemical, and inflammatory signals (cytokines), as well as antioxidant enzymes in African catfish (Clarias gariepinus) exposed to lead (Pb) and MPs individually and combined for 15 days (acute toxicity experiment). The fish were split into four groups, the first of which was the control group. The second group received exposure to 1 mg/L of lead nitrate [Pb(NO3)2]. The third group was given 100 mg/L of MPs. A solution containing 100 mg/L of MPs and 1 mg/L of lead nitrate [Pb(NO3)2] was administered to the fourth group (the combination group). According to the findings, when MPs and Pb were combined for 15 days, the red blood cells (RBCs), thrombocytes, and lymphocytes were significantly reduced in comparison to the control fish. When compared to the control fish, the fish exposed to MPs and Pb alone or together showed a significant rise in blood interleukin-1β (IL-1β) and interleukin-6 (IL-6) cytokines. Both MPs and Pb exposure in catfish resulted in significant changes in the plasma electrolytes. The fish treated with MPs and Pb individually or in combination showed significant reduction in superoxide dismutase (SOD) and total antioxidant capacity (TAC) levels compared to the control group. The fish exposed to the combined action of MPs and Pb showed a considerable modification in all biochemical markers. The difference in the mean concentration of Pb (mg/L) between the fish exposed to Pb alone and the fish subjected to Pb and MPs combination was not statistically significant. In conclusion, according to this investigation, exposure to Pb caused an insignificant increase in Pb accumulation when MPs were present. However, co-exposure may result in anemia, cellular harm, extremely high levels of oxidative stress, and an inflammatory reaction.

Phthalates (PAEs) and reproductive toxicity: Hypothalamic-pituitary-gonadal (HPG) axis aspects

Phthalates (PAEs) are widely used for their excellent ability to improve plastic products. As an essential endocrine axis that regulates the reproductive system, whether dysfunction of the hypothalamic-pituitary-gonadal (HPG) axis is involved in reproductive toxicity mediated by environmental endocrine disruptors PAEs has become a hot topic of widespread concern. This study systematically reviewed the adverse effects of multiple PAEs on the HPG axis in different models and objectively discussed the possible underlying mechanisms. The abnormal release of gonadotropin-releasing hormone and gonadotropin, dysfunction of sex hormone receptors and steroid hormone synthesis, and general damage, including cell proliferation, oxidative stress, apoptosis, and autophagy have been confirmed to be involved in this process. Although it is widely established that PAEs induce HPG axis dysfunction, the specific mechanisms involved remain unclear. From a systematic review of relevant publications, it appears that the abnormal expression of peroxisome proliferator-activated, aryl hydrocarbon, and insulin receptors mediated by PAEs is key upstream event that induces these adverse outcomes; however, this inference needs to be further verified. Overall, this study aimed to provide reliable potential biomarkers for future environmental risk assessment and epidemiological investigation of PAEs.

Toxicity assessment of microplastic (MPs); a threat to the ecosystem

Plastic is now considered part and parcel of daily life due to its extensive usage. Microplastic (MP) pollution is becoming a growing worry and has been ranked as the second most critical scientific problem in the realm of ecology and the environment. Microplastics are smaller in size than the plastic and are more harmful to biotic and as well as abiotic environments. The toxicity of microplastic depends upon its shape and size and increases with an increase in its adsorption capacity and their toxicity. The reason behind their harmful nature is their small size and their large surface area-to-volume ratio. Microplastic can get inside fruits, vegetables, seeds, roots, culms, and leaves. Hence microplastic enters into the food chain. There are different entry points for microplastic to enter into the food chain. Such sources can include polluted food, beverages, spices, plastic toys, and household (packing, cooking, etc.). The concentration of microplastic in terrestrial environments is increasing day by day. Microplastic causes the destruction of soil structure; destroys soil microbiota, cause depletion of nutrients in the soil, and their absorption by plants decreases plant growth. Apart from other environmental problems caused by microplastic, human health is also badly affected by microplastic pollution present in the terrestrial environment. The presence of microplastics in the human body has been confirmed. Microplastic enters into the body of humans in different possible ways. According to their way of entering the body, microplastics cause different diseases in humans. MPs also cause negative effects on the human endocrine system. At the ecosystem level, the impacts of microplastic are interconnected and can disrupt ecological processes. Although recently different papers have been published on several aspects of the microplastic present in the terrestrial environment but there is no complete overview that focus on the interrelationship of MPs in plants, and soil and their effect on higher animals like a human. This review provides a completely detailed overview of existing knowledge about sources, occurrences, transport, and effects of microplastic on the food chain and soil quality and their ecotoxicological effects on plants and humans.

Global hotspots and trends in interactions of microplastics and heavy metals: a bibliometric analysis and literature review

Microplastics (MPs) are identified as emerging contaminants; however, their interactions with heavy metals in the environment have not been well elucidated. Here, the research progress, hotspots, and trends in the interactions of MPs and heavy metals were analyzed at a global scale using a bibliometric analysis combined with a literature review. We comprehensively searched the Web of Science Core Collection database from 2008 to July 5, 2022. A total of 552 articles published in 124 journals were selected, which came from 70 countries and 841 institutions. The most contributing journals, countries, institutions, and authors were identified. Visualization methods were used to identify high co-citation references and hot keywords in the 552 articles. Evolutionary and cluster analyses of hot keywords suggested several research hotspots in the co-contamination of MPs and heavy metals, including their toxicity and bioaccumulation, the adsorption and desorption behaviors, the environmental pollution and risk assessment, and their detection and characterization. Based on the current research status, several directions of priority are recommended to understand the interactions between MPs and heavy metals and their potential risks. This article can help recognize the current research status and future directions in this field.

Toxicity of microplastics and nanoplastics: invisible killers of female fertility and offspring health

Microplastics (MPs) and nanoplastics (NPs) are emergent pollutants, which have sparked widespread concern. They can infiltrate the body via ingestion, inhalation, and cutaneous contact. As such, there is a general worry that MPs/NPs may have an impact on human health in addition to the environmental issues they engender. The threat of MPs/NPs to the liver, gastrointestinal system, and inflammatory levels have been thoroughly documented in the previous research. With the detection of MPs/NPs in fetal compartment and the prevalence of infertility, an increasing number of studies have put an emphasis on their reproductive toxicity in female. Moreover, MPs/NPs have the potential to interact with other contaminants, thus enhancing or diminishing the combined toxicity. This review summarizes the deleterious effects of MPs/NPs and co-exposure with other pollutants on female throughout the reproduction period of various species, spanning from reproductive failure to cross-generational developmental disorders in progenies. Although these impacts may not be directly extrapolated to humans, they do provide a framework for evaluating the potential mechanisms underlying the reproductive toxicity of MPs/NPs.

Influences of chronic copper exposure on intestinal histology, antioxidative and immune status, and transcriptomic response in freshwater grouper (Acrossocheilus fasciatus)

Copper (Cu) contamination is commonly found in both natural water environments and fish farms, and it can cause severe damage to different fish organs, but Cu-induced intestinal damage has been rarely studied. This study subjected three groups of freshwater grouper (Acrossocheilus fasciatus) (initial weight: 1.56 ± 0.10 g) to 0 mg/L, 0.01 mg/L, and 0.04 mg/L Cu2+ for 30 days, named Con, Cu0.01, and Cu0.04 groups, respectively. The histological observation indicated that the Cu0.04 group caused a significant decrease in villus length, lamina propria width, and muscular thickness compared to the Con group (P < 0.05). Additionally, the Cu0.04 group significantly increased intestinal superoxide dismutase (SOD), glutathione peroxidase (GPx), lysozyme (LZM) activities, as well as malondialdehyde (MDA) content than the Con group (P < 0.05). Meanwhile, the Cu0.01 and Cu0.04 groups showed significantly increased immunoglobulin M (IgM), complement 3 (C3), and glutathione (GSH) contents than the Con group (P < 0.05). Transcriptomic analysis revealed a total of 101 differentially expressed genes (DEGs), including 47 up-regulated and 54 down-regulated DEGs, were identified between the Cu0.04 and Con groups. Notably, the DEGs were mainly related to intestinal structure construction, immune functions, apoptosis, and resistance to DNA damage and pathogen infection. The findings suggest that chronic Cu exposure caused intestinal histological alterations, activated the antioxidative and immune systems, and induced systematic adaptation to cope with the physical barrier injury, DNA damage, and potential pathogen growth.

Multiple effects of ZnO nanoparticles on goldfish (Carassius auratus): Skin mucus, gut microbiota and stable isotope composition

The skin and the gut are direct target tissues for nanoparticles, yet attention to effects of metal-based nanoparticles (MNPs) on these two and the discrepancy in these effects remain inadequate. Here, effects of ZnO nanoparticles (nZnO) on skin mucus and gut microbiota of goldfish (Carassius auratus) were investigated, as well as further elements turnover and metabolic variations. After 14 days of exposure, considerable variations in levels of biomarkers (protein, glucose, lysozyme and immunoglobulin M) in skin mucus demonstrated significant stress responses to nZnO. nZnO exposure significantly reduced the abundance of Cetobacterium in the gut while increased that of multiple pathogens, and further leading to down-regulation of pathways such as carbohydrate metabolism, translation, and replication and repair. Decreased δ¹⁵N values indicated declined N turnover in vivo, further demonstrating the negative effect of nZnO on metabolism in the organism. Integration analysis of each biomarker using the biomarker response index version 2 (IBRv2) revealed concentration-dependent effects of nZnO on skin mucus, while effects on physiology in vivo was not, demonstrating the discrepancy in the toxicity pathways and toxic effects of nZnO on different tissues. This work improved our understanding about the comprehensive toxicity of nZnO on aquatic organism.

Size-specific effects of microplastics and lead on zebrafish

Microplastics (MPs) can adsorb heavy metals and induce combined toxicity to aquatic organisms. However, the combined effects on the gut-liver and gut-brain axes are yet to be fully comprehended. This study investigated the combined effects of polystyrene microplastics (PS-MPs) with two concentrations (20 and 200 μg/L) and three sizes (0.1, 10, and 250 μm) and Pb (50 μg/L) on zebrafish through gut-liver and gut-brain axes. The results showed that the combined exposure of 0.1 μm PS-MPs and lead resulted in the most significant changes to the community diversity of gut microbiota. The combined exposures of PS-MPs (0.1 μm and 250 μm PS-MPs) and Pb significantly down-regulated expression of zo-1 and occludin but increased the lipopolysaccharide content in zebrafish liver compared to the PS-MPs or Pb alone exposure groups, indicating impaired gut barrier function. Subsequent studies showed that combined exposure of PS-MPs (0.1 μm and 250 μm) and Pb combined groups induced liver inflammation through the TLR4/NF-κB pathway. Moreover, all exposure groups had an impact on the expression of genes related to bile acid metabolism (cyp7a1, fgf19, abcb11b, and slc10a2) and neurotransmitters (tph1a, tph2, pink, and trh). The findings of this study provide new evidence on the combined effects of MPs and metals, which are significant for their hazard identification and risk assessment.

Early life stage exposure to cadmium and zinc within hour affected GH/IGF axis, Nrf2 signaling and HPI axis in unexposed offspring of marine medaka Oryzias melastigma

Information on transgenerational effects of cadmium (Cd) and zinc (Zn) within hour of exposure is scarce. To the end, larvae of marine medaka Oryzias melastigma at 0 day-post-hatching (dph) were subjected to LC₅₀ for 96-h of Cd or Zn for 0.5 and 6 h, and then transferred into clear water for 95 days until the generation of offspring larvae at 25 dph. Growth, antioxidant capacity and stress response in offspring larvae were examined. Exposure to Zn for 0.5 h or Cd for 0.5 h and 6 h promoted growth performance and reduced total antioxidant capacity (TAC) and activities of superoxide dismutase (SOD) and catalase (CAT). Malondialdehyde (MDA) and cortisol levels declined in larvae following Zn exposure for 0.5 h, whereas Cd exposure increased MDA content and did not affect cortisol levels. These physiological changes could be partially explained by transcription of genes in the hormone/insulin-like growth factor-I (GH/IGF) axis, NF-E2-related factor 2 (Nrf2) signaling, and hypothalamus-pituitary-interrenal (HPI) axis. For example, Zn exposure for 0.5 h up-regulated genes encoding growth hormone (gh) and insulin-like growth factor binding protein (igfbp1) and down-regulated mRNA levels of nrf2, Kelch-like-ECH-associated protein 1 gene (keap1a), keap1b, sod1, mineralocorticoid receptor (mr), corticotropin-releasing hormone receptor (crhr1), corticotropin-releasing hormone binding protein (crhbp), cytochrome P450 (cyp11a1, cyp17a1) and hydroxysteroid dehydrogenase (hsd3b1). Cd exposure for 0.5 and 6 h up-regulated growth hormone release hormone (ghrh) and igfbp1, down-regulated nrf2 and keap1a, and did not affect mRNA levels of HPI axis genes. Taken together, this study demonstrated that short-term metal exposure during larvae phase had positive and negative effects on offspring even after a long recovery.

Dietary berberine against intestinal oxidative stress, inflammation response, and microbiota disturbance caused by chronic copper exposure in freshwater grouper (Acrossocheilus fasciatus)

Berberine (BBR) is known for its strong antioxidant, anti-inflammatory, and capacity to preserve intestinal microbiota balance in fish. This study aimed to investigate the protective effects of berberine against copper-induced toxicity in the intestine of freshwater grouper Acrossocheilus fasciatus. The experiment involved four groups: a control group, a Cu group exposed to 0.02 mg/L Cu²⁺, and two BBR groups fed with 100 or 400 mg/kg of berberine diets and exposed to the same Cu²⁺ concentration. Three replicates of healthy fish (initial weight 1.56 ± 0.10 g) were subjected to their respective treatments for 30 days. Results showed that none of the treatments significantly affected the survival rate, final weight, weight gain, and feed intake (P > 0.05). However, supplementation with 100 and 400 mg/kg of BBR significantly lowered the antioxidant activities, and glutathione peroxidase (gpx) and superoxide dismutase (sod) expression levels, as well as reduced malondialdehyde (MDA) content caused by Cu²⁺ exposure (P < 0.05). Berberine inclusion significantly downregulated proinflammatory factors NLR family pyrin domain containing 3 (nlrp3), interleukin 1 beta (il1β), interleukin 6 cytokine family signal transducer (il6st) but upregulated transforming growth factor beta 1 (tgfβ1) and heat shock 70kDa protein (hsp70) expression. Moreover, berberine at both levels maintained the intestinal structural integrity and significantly improved gap junction gamma-1 (gjc1) mRNA level compared to the Cu group (P < 0.05). Based on 16S rDNA sequencing, the richness and diversity of intestinal microbiota in different groups were not significantly influenced. Berberine reduced the Firmicutes/Bacteroidota ratio and stifled the growth of some specific pathogenic bacteria such as Pseudomonas, Citrobacter, and Acinetobacter, while boosting the richness of potential probiotic bacteria, including Roseomonas and Reyranella compared with the Cu group. In conclusion, berberine showed significant protective effects against Cu²⁺-induced intestinal oxidative stress, inflammation response, and microbiota disturbance in freshwater grouper.