Aquatic Organisms Research Articles

A portable multi-taxa phenotyping device to retrieve physiological performance traits

Organismal phenotyping to identify fitness traits is transforming our understanding of adaptive responses and ecological interactions of species within changing environments. Here we present a portable Multi-Taxa Phenotyping (MTP) system that can retrieve a suite of metabolic and photophysiological parameter across light, temperature, and/or chemical gradients, using real time bio-optical (oxygen and chlorophyll a fluorescence) measurements. The MTP system integrates three well-established technologies for the first time: an imaging Pulse Amplitude Modulated (PAM) chlorophyll a fluorometer, custom-designed well plates equipped with optical oxygen sensors, and a thermocycler. We demonstrate the ability of the MTP system to distinguish phenotypic performance characteristics of diverse aquatic taxa spanning corals, mangroves and algae based on metabolic parameters and Photosystem II dynamics, in a high-throughput capacity and accounting for interactions of different environmental gradients on performance. Extracted metrics from the MTP system can not only provide information on the performance of aquatic taxa exposed to differing environmental gradients, but also provide predicted phenotypic responses of key aquatic organisms to environmental change. Further work validating how rapid phenotyping tools such as the MTP system predict phenotypic responses to long term environmental changes in situ are urgently required to best inform how these tools can support management efforts.

Proteomic insights into extracellular matrix dynamics in the intestine of Labeo rohita during Aeromonas hydrophila infection.

The study underscores the critical role of the extracellular matrix (ECM) and its associated proteins in the immune response of aquatic organisms during bacterial infections like Aeromonas hydrophila. Understanding the intricate interplay between ECM alterations and immune response pathways provides crucial insights for developing effective disease control strategies in aquaculture. By identifying key proteins and pathways involved in host defense mechanisms, this research lays the groundwork for targeted interventions to mitigate the impact of bacterial infections on fish health and aquaculture production.

Regional distribution differences of antibiotics in tropical marine aquaculture area: Insights into antibiotic management and risk assessment

In recent years, global demand for marine aquaculture products has led to a significant rise in antibiotic use, particularly in tropical coastal aquaculture areas However, research on antibiotic residues in these environments remains limited, hindering a comprehensive understanding of their environmental presence and associated risks. This study investigates the regional distribution, ecological risks, and sources of 44 antibiotics in seawater across four coastal aquaculture areas in Hainan island (Wenchang, Sanya, Danzhou, and Wanning). Among the 44 antibiotics tested across 42 sampling sites, all were detected with a 100 % detection rate. Antibiotics such as Trimethoprim (TMP), Sulfanitran (APNPS), Sulfaquinoxaline (SQ), Sulfadimethoxine (SDT), Chloramphenicol (CHP), and Florfenicol (FLO) were consistently detected across all sampling sites. Total concentrations of detected antibiotics ranged from 0 to 818.79 ng.L−1, with sulfonamide antibiotics ranging from 0 to 629.49 ng.L−1, chloramphenicol antibiotics from 0 to 87.39 ng.L−1, tetracyclines from 0 to 221.39 ng.L−1, and fluoquinolones from 0 to 272.08 ng.L−1. The highest levels of antibiotic pollution were observed at the W5 sampling site in Wenchang, attributed to aquaculture wastewater discharge, while no antibiotics were found at D12 in Danzhou. In these regions, source analysis identified aquaculture and domestic sewage as the primary contributors to antibiotic pollution in these regions. Correlation analysis with environmental factors revealed significant influences of factors such as SAL, kPa, TN, SPC, and pH on sulfonamide and chloramphenicol antibiotics. Health risk assessment indicated moderate to high risks to aquatic organisms from antibiotics like NOR, CIP, ENR, OFL, TMP, and SMX in the study areas, underscoring the need for preventive measures, stricter regulation of antibiotic use, and enhanced ecological risk monitoring in aquaculture regions. This study provides critical insights into antibiotic contamination in Hainan's coastal aquaculture areas, highlighting the urgent need for further research into the occurrence and ecological impacts of these emerging pollutants in marine environments.

Active pharmaceutical contaminants in drinking water: myth or fact?

Global water availability has been affected by a variety of factors, including climate change, water pollution, urbanization, and population growth. These issues have been particularly acute in many parts of the world, where access to clean water remains a significant challenge. In this context, preserving existing water bodies is a critical priority. Numerous studies have demonstrated the inadequacy of conventional water treatment processes in removing active pharmaceutical ingredients (APIs) from the water. These pharmaceutical active compounds have been detected in treated wastewater, groundwater, and even drinking water sources. The presence of APIs in water resources poses a significant threat not only to aquatic organisms but also to human health. These emerging contaminants have the potential to disrupt endocrine systems, promote the development of antibiotic-resistant bacteria, and bioaccumulate in the food chain, ultimately leading to unacceptable risks to public health. The inability of current conventional treatment methods to effectively remove APIs from water has raised serious concerns about the safety and reliability of water supplies. This issue requires immediate attention and the development of more effective treatment technologies to safeguard the quality of water resources and protect both aquatic ecosystems and human health. Other treatment methods, such as nanotechnology, microalgal treatment, and reverse osmosis, are promising in addressing the issue of API contamination in water resources. These innovative approaches have demonstrated higher removal efficiencies for a wide range of APIs compared to conventional methods, such as activated sludge and chlorination, which have been found to be inadequate in the removal of these emerging contaminants. The potential of these alternative treatment technologies to serve as effective tertiary treatment. To address this critical challenge, governments and policymakers should prioritize investment in research and development to establish effective and scalable solutions for eliminating APIs from various water sources. This should include comprehensive studies to assess the performance, cost-effectiveness, and environmental sustainability of emerging treatment technologies. The emerging contaminants should be included in robust water quality monitoring programs (Aus der Beek et al. in Environ Toxicol Chem 2016;35(4):823-835), with strict regulatory limits enforced to protect public health and the environment. By doing so, the scientific community and regulatory authorities can work together to develop a multi-barrier approach to safeguarding the water resources and ensuring access to safe, clean water for all. This review explores the potential of alternative treatment technologies to serve as viable solutions in the fight against API contamination. Innovative approaches, including nanotechnology, microalgal treatment, and reverse osmosis, have demonstrated remarkable success in addressing this challenge, exhibiting higher removal efficiencies compared to traditional methods.

Molecular imprinting based sensor system developed using polymeric nanoparticles for detecting 17β‐estradiol in agricultural wastewater

AbstractMicro pollutants pose a significant issue in water ecosystems. Particularly high concentrations of 17β‐estradiol (E2) have been identified in agricultural wastewater, which poses harmful effects on aquatic organisms and disrupts ecosystem balance. Therefore, effective determination of E2 from water sources is crucial. This study developed a biosensor capable of detecting E2 in wastewater using specific polymer nanoparticle synthesis through molecular imprinting. Est‐imp‐poly(multi‐walled carbon nanotubes‐glycidyl methacrylate [MWCNT‐GMA]) polymer nanoparticles were synthesized using a surfactant‐free emulsion polymerization method, and their characterization was conducted using FTIR and scanning electron microscopy (SEM) technologies. The Qmax value for Est‐imp‐poly(MWCNT‐GMA) nanoparticles in a 1 mg/mL E2 solution was determined to be 140 ppm. Comparing adsorption capacities, the molecularly imprinted nanoparticles (MIP) showed nearly five times higher E2 adsorption compared to non‐imprinted polymers (NIP). The Est‐imp‐poly(MWCNT‐GMA)‐Nafion/screen‐printed electrode (SPE) system was employed for analyzing wastewater samples. The current measurements taken at various concentrations in the wastewater consistently matched the E2 concentration calibration curve. The limit of detection (LoD) and limit of quantification (LoQ) were determined to be 0.042 and 0.12 μM, respectively. The biosensor demonstrated a linear working range from 0.12 to 50 μM, with a high correlation coefficient (R2 = 0.9927). These results highlight the potential of the developed biosensor for detecting E2 in real samples.

Source and health risks of trace metals in Clarias batrachus and Chrysichthys nigrodigitatus from surface waters in Bayelsa State, Nigeria: a probabilistic model

IntroductionHuman activities have inadvertently led to the release of harmful substances, including trace metals, into aquatic environments, with consequential impacts on aquatic organisms and potential health risks for consumers. This research assessed the presence, origins, and health implications of trace elements within the muscles of Clarias batrachus and Chrysichthys nigrodigitatus from the Bomadi and Gbotebo rivers and their surroundings in Bayelsa State, Nigeria.MethodsThirty samples from each fish species were collected and analyzed to conduct the study. Through the use of an atomic absorption spectrophotometer, the researchers determined the concentrations of trace metals, including iron, copper, zinc, lead, nickel, cadmium, and cobalt, in the fish tissues.Results and discussionThe concentrations of the metals within the two fish species varied, with notable differences in zinc and cadmium levels. Utilizing statistical analyses like Pearson correlation, principal component analysis (PCA), and hierarchical cluster analysis (CA), it was established that the trace metals originated from diverse sources. The study then evaluated health risks associated with these trace elements, considering both non-carcinogenic and carcinogenic hazards for different age groups. The results indicated that children’s total target hazard quotient fell below 1 for both fish species, implying a limited tendency toward non-carcinogenic risks through lifelong fish consumption. However, in some adult fish samples, the quotient exceeded 1, indicating a higher potential for non-carcinogenic risks. Regarding carcinogenic hazards, the mean risks were generally lower than the accepted threshold, except for lead in both fish species among adults and children. Stricter values highlighted that only lead concentrations in fish from both categories were deemed acceptable. Consequently, this study highlights the importance of raising awareness among consumers who buy fish from the studied region. Moreover, consistent monitoring of potentially harmful trace elements in water, sediments, and fish is recommended to safeguard consumer health and well-being.

Perspectives on the Toxic Effects of Micro- and Nanoplastics on the Environment: A Bibliometric Analysis of the 2014 to 2023 Period.

Over the past decade, micro- and nanoplastics (MNPs) have garnered significant attention due to their frequent detection in and potential toxic effects on the environment and organisms, making them a serious threat to human health. To comprehensively understand the research on MNPs' toxicity, we employed the R language-based Bibliometrix toolkit (version 4.3.0), VOSviewer (version 1.6.11) and CiteSpace (version 6.3.R1) to perform statistical and visual analyses of 3541 articles pertaining to MNPs' toxicity between 2014 and 2023, which were retrieved from the Web of Science Core Collection (WOSCC) database. The analysis revealed that research related to MNPs' toxicity has experienced a rapid increase in recent years. China's particularly prominent influence in the field of MNPs' toxicity is evidenced by its academic exchanges and the establishment of a mature cooperation system with other countries (regions), such as the USA and Germany. Studies related to MNPs' toxicity are primarily published in leading journals, including the Science of the Total Environment, Environmental Pollution, and the Journal of Hazardous Materials. The Chinese Academy of Sciences was identified as the leading institution in terms of research on MNPs' toxicity, contributing 203 papers to the total number of studies published. Keyword co-occurrence and burst analyses indicated that the current research on MNPs' toxicity mainly focuses on the toxic effects of MNPs on aquatic organisms, the combined toxicity of MNPs and other contaminants, and the toxic effects and mechanisms of MNPs. Future research should integrate computational toxicology and toxicomics to enhance our understanding of MNPs' toxicity mechanisms and assess the potential health risks posed by atmospheric MNPs.

Morphology and molecular phylogeny of four epibiotic ciliates (Ciliophora, Peritrichia) from farmed red swamp crayfish Procambarus clarkii Girard, 1852, with notes on the geographic distributions of related taxa

Aquaculture of red swamp crayfish Procambarus clarkii is an emerging farming industry in China. As shown recently, one of the most significant diseases affecting the red swamp crayfish is caused by overabundance of epibiotic peritrichs, a group of ciliated protists that are commonly found living as epibionts on aquatic animals. Nevertheless, few studies focusing on this issue have been performed. As part of a faunal study carried out in the Lake Weishan Wetland, China, four colonial sessilid peritrichs, namely Epicarchesium granulatum, Epistylis bimarginata, Epistylis semiciculus, and Zoothamnium procerius, attached to P. clarkii are documented. For each species, redescriptions and improved diagnoses are supplied. As a further aid to identification, 14 new rDNA sequences of these four and a closely related species were obtained. In addition, as an aid for future studies on epibiotic ciliates, we supply a list and information about recent integrative studies that document the geographic distributions of related taxa.

Immunotoxic response of bio-based plastic on early life stage zebrafish (Danio rerio): A safe alternative to petroleum-based plastics?

Bio-based plastics are marketed as environmentally friendly alternatives to petroleum-based plastics, although they require specific composting conditions for degradation, which leads to their accumulation in the environment and potential risks to aquatic organisms. We hypothesized that the accumulation of bio-based plastics may induce immunotoxic responses in fish. Our research focused on the accumulation and immunotoxicity of 80 nm polylactic acid (PLA) and polystyrene (PS) (0.1–10 mg/L) on early life stage zebrafish (Danio rerio) exposed for 7 days. Compared to PS, there was a higher accumulation of PLA in larvae. Exposure to PLA resulted in a significant increase in neutrophils and macrophages, while immune protein levels such as Complement 3 (C3), Immunoglobulin M (IgM), and C-reactive protein (CRP) were significantly reduced. Furthermore, the mRNA expression of pro-inflammatory cytokines, including tnf-α and il-6, were significantly elevated in PLA treatments. Additionally, PLA-exposed zebrafish were more susceptible to infection by Vibrio parahaemolyticus. Interestingly, at the same concentration, exposures to PS did not induce significant changes in macrophages or immune protein levels, C3 and IgM. This suggests that PLA has a greater immunotoxic response relative to PS. Our research findings contradict the popular belief that bio-based plastics are non-toxic and harmless, which may have potential risk to aquatic organisms.

In silico Investigations of Al2O3 and NiO Nanoparticles Interactions with Antioxidant Enzymes of Fresh Water Fish O.mossambicus

Metal oxide nanoparticles caused hazardous to aquatic organisms, especially fishes. Nanomaterials of Aluminium and nickel oxide are applied in wide range of applications. However the toxicity of these metal oxide nanoparticles on freshwater fish is very scarce. In this study, we investigated the toxic impact of these two nanoparticles through an in silico approach. The antioxidant enzymes /proteins of SOD, CAT and GST in fish O.mossambicus were docked against Al2O3 and NiO NPs. These enzymes are responsible for oxidative metabolism of a large number of nanomaterials. Induction of oxidative stress by NPs exposure leads to inhibition of these enzymes. The targeted proteins SOD, CAT and GST were retrieved from Alpha fold database and docked with ligands. Molecular docking was conducted using CB - Dock and AutoDock Vina software tools to find the binding affinity and interaction with amino acids of each protein. The target proteins found to strongly interact with ligands through hydrogen bonding and metal coordination interactions. The lowest binding energy shows strong binding of ligands with proteins. Docking results revealed that the amino acids residues of SOD, CAT and GST enzymes are strongly bind with the Al2O3 and NiO NPs in its active site and causes inhibition of the enzymes activities. CAT exhibited lowest binding affinity of (-4.0 Kcal/mol) among all enzymes and significantly inhibited by NiO NPs, followed by GST (-3.4 Kcal/mol), likewise CAT (-1.7 Kcal/mol) and GST (-1.8 Kcal/mol) was moderately inhibited by Al2O3 NPs. SOD inhibited insignificantly by both the NPs. In conclusion, NiO NPs effectively inhibit antioxidant enzymes activity than Al2O3 NPs.

THE EFFECT OF LEAD ON THE DEVELOPMENT OF EMBRYOS AND LARVAE OF DANIO RERIO

The early stages of development of aquatic organisms, including fish, are inherently vulnerable to the effects of lead (Pb) and other water-polluting metals. However, reports of harmful effects of environmentally significant Pb levels are limited. To this end, we exposed the embryos of old Danio rerio fish 2.5 hours after fertilization (hours) to a range of Pb concentrations covering environmentally significant levels (10 μm; 20 μm; 40 μm; 60 μm), up to 120h. Exposure negatively affected the development and survival of the embryos of danio fish, causing mortality associated with embryo coagulation, depending on concentration. At 24 hpf, the highest level of exposure (60 μm Pb) led to impaired embryo activity, characterized by a decrease in burst activity and the number of movements performed by embryos per minute. At 72 hpf, all the embryos hatched in all exposure concentrations. Morphological abnormalities and an increase in mRNA expression were observed. These results indicate that the Pb content within ecologically significant levels may be harmful to developing danio fish.

River algal blooms can be estimated by remote sensing reflectance

Abstract River eutrophication is difficult to diagnose and estimate quantitatively because of its complex degradation mechanism in large river systems. Conventional monitoring and modeling methods are limited to accurately revealing the evolution process and trends of river aquatic organisms. In the present study, based on HJ-1A/1B CCD sensor, combined with genetic algorithm (GA) and regression tree (GART), a remote sensing inversion prediction model was established; the model can estimate algal blooms in the Han River affected by China’s Middle Route of the South-to-North Water Diversion Project (SNWTP). During the outbreak of algal blooms, the near-infrared band reflectance evidently increased between 2009 and 2015, with increasing algal density. The algal density in the downstream of the Han River has a nearly synchronous positive change with the reflectance in the B4 (near-infrared) band and a nearly synchronous reverse change with the B1 (blue) band. B1 and B4 screened by GA reduced redundancy by 14%, leading to a good prediction performance (R 2 = 0.88). According to GART and partial dependence analysis, the B4 band is a crucial characterization factor of algal blooms in the Han River. When the remote sensing band was in the range of B1 ⩾ 0.085 and B4 ⩽ 0.101, the algal density was lower than 0.15 × 107 cells l−1, indicating no algal bloom in the downstream of the Han River. When B4 was >0.103 and B1 ⩽ 0.076, algal density was higher than 1 × 107 cells l−1 and algal blooms were very likely to occur. These findings could provide a scientific reference for diagnosing and predicting large-scale water ecological degradation in similar watersheds.

Degradation of enestroburin in the water-sediment system: kinetics, transformation products identification and toxicity assessment to aquatic organisms

ABSTRACT Pesticides inevitably enter the water environment in the process of use. However, the degradation and its transformation products (TPs) of enestroburin in water-sediment systems are not yet known. This study systematically investigated the degradation behaviour of enestroburin through indoor simulation experiments. The study demonstrated that the different organic content of sediments and oxygen conditions had a little effect on the degradation. The study also analysed transformation products by UPLC-QTOF-MS and MetabolitePilot software. A total of 3 TPs of enestroburin were identified, and one product (M-381) was confirmed and quantified. Based on these transformation products, the pathways of enestroburin were supposed, namely hydrolysis of chlorobenzene, hydrolysis of ester group and electrophilic substitution of benzene ring. Finally, ECOSAR software was utilised to predict the potential toxicity of the proposed TPs towards fish, daphnids, and green algae. The toxicity of TPs to aquatic organisms is lower than the parent compound, but they are still toxic. The study results provide data to support the safe use of enestroburin and provide a reference for the degradation and transformation of other strobilurin fungicides.

Ferric uptake regulator (Fur) in Vibrio mimicus acts as an activator of citrate cycle and oxidative phosphorylation pathways, while enhancing virulence potential

Ferric uptake regulator (Fur) is a crucial bacterial regulator that controls the uptake of iron by bacteria, hence influencing their survival and pathogenicity. Vibrio mimicus is an epidemic pathogen that is harmful to aquatic animals and human health, with the characteristics of rapid onset and high mortality after infecting the fish. At present, the function and mechanism of Fur in V. mimicus are still unclear. In this study, the fur gene deletion strain and complementation strain of V. mimicus were constructed. Following fur deletion, proteomic analysis revealed that the abundance of 258 proteins was considerably up-regulated while the abundance of 307 proteins was dramatically down-regulated. The primary roles of these differentially expressed proteins were in a variety of pathways, including virulence, metabolism, enzymes, and so on. Among them, citrate cycle and oxidative phosphorylation were the main pathways affected by Fur. The activities of key enzymes in these two pathways were assessed. The results indicated a decrease in the activities of respiratory chain complexes II and IV, succinate dehydrogenase (SDH), and α-ketoglutarate dehydrogenase (α-KGDH) in the Δfur strain. Conversely, the activity of isocitrate dehydrogenase (NAD-IDH) was increased. Phenotypic characterization showed that the Δfur strain exhibited delayed growth, reduced motility, defective biofilm formation, decreased resistance to oxidative stress, increased adhesion, and decreased virulence. Besides, the LD50 of the Δfur strain was 31-fold higher than that of the WT strain. These results indicate that Fur serves as an activator for the citrate cycle and oxidative phosphorylation pathway in V. mimicus, and contributing to its virulence. Our findings enhance the understanding of the biological functions of Fur and lay the groundwork for further investigation into the regulatory mechanisms of Fur in V. mimicus.

Potansiyel bisphenol-A ikameleri sucul yaşam için gerçekten güvenli mi? Birincil üreticiler üzerindeki etkisi

Bisphenol A threat to environmental health and human health and has been added to the Candidate List as Very High Concern Substances by the European Chemicals Agency. This led to the replacement of bisphenol A (BPA) with bisphenol analogues, which were considered "safer". However, there are very few scientific studies on the impact of BPA analogues on the environment. In this study, three analogues bisphenol B (BPB), bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE) were selected to investigate their ecotoxicological effects on the marine phytoplankton species Phaeodactylum tricornutum, which is representative of primary producers. Phaeodactylum tricornutum was exposed to different concentrations (0.5, 0.8, 1.0, 1.5, 2.0 mg/L) of BPB, BADGE and BFDGE analogues for 72 hours and the toxicity values of three BPA analogues were calculated by OECD 201 algal growth inhibition assay (IC50/EC50). In the light of the data obtained, algal growth inhibition (IC50/EC50) values for marine phytoplankton Phaeodactylum tricornutum were determined as 3.91 mg-BPA/L, 7.83 mg-BPB/L, 5.69 mg-BFDGE/L, 11.71 mg-BADGE/L. The results revealed that BPB, BFDGE and BADGE showed lower toxicity to Phaeodactylum tricornutum compared to BPA algal growth inhibition (3.91 mg-BPA/L). Therefore, it is necessary to share the results of the adverse effects of BPA analogues on aquatic organisms and to conduct ecotoxicological risk assessments.

Enhancment of zebrafish (Danio rerio) immune and antioxidant systems using medicinal plant extracts encapsulated in alginate-chitosan nanocapsules with slow sustained release.

This study aimed to screen 10 medicinal plant extracts on zebrafish (Danio rerio), evaluating their impact on the complement system, immunoglobulin M (IgM) levels, lysozyme, and peroxidase activity, while also enhancing their efficacy through the gradual release using alginate-chitosan nanocapsules. The prepared methanolic extracts were combined with fish feed. The fish were divided into 12 groups, including 10 treatment groups, a positive and a negative control group. Results showed varying impacts of the extracts on the immune and antioxidant systems, with Cinnamon (Cinnamon cassia) and Hypericum (Hypericum perforatum) extracts demonstrating the most significant effects. Subsequently, Cinnamon and Hypericum extract were encapsulated in alginate-chitosan nanocapsules to assess their impact on zebrafish immune parameters, separately and synergistically. Gradual release of the extracts from the nanocapsules was observed, with slower release at pH 2 compared to pH 7. Overall, Cinnamon and Hypericum extracts exhibited substantial immune system enhancement, and their encapsulation in nanocapsules improved their effects on zebrafish immune parameters. These findings suggest using these encapsulated extracts to enhance immune responses in aquatic organisms.

Combined effects of polyvinyl chloride or polypropylene microplastics with cadmium on the intestine of zebrafish at environmentally relevant concentrations

Cadmium (Cd) is a common additive in polyvinyl chloride (PVC) and polypropylene (PP) plastics. Aquatic organisms were inevitably co-exposed to PVC/PP microplastics (MPs) and Cd, but their combined toxicity is still unknown. In this study, adult zebrafish were exposed to 200 μg/L MPs (PVC or PP) and 10 μg/L Cd alone or in combination for 28 days to investigate their toxicity and mechanisms. Results showed that combined exposure with PVC/PP enhanced the Cd accumulation in the zebrafish intestine. Subsequently, toxicology analyses showed that both PVC and PP possessed synergistic toxicity with Cd, manifested by the exfoliation and necrosis of intestinal epithelial cells, and increased levels of interleukin-1β (IL-1β), superoxide dismutase (SOD) and malondialdehyde (MDA). PP exhibited a stronger synergistic effect than PVC. Integration of non-targeted metabolomics and 16S rRNA gene sequencing revealed that combined exposure to PVC and Cd induced intestine toxicity mainly through bile acid (BA) biosynthesis, fructose (Fru) and mannose (Man) metabolism, and pentose phosphate pathway (PPP). The combined exposure of PP and Cd induced toxicity through the arginine (Arg) and glutathione (GSH) metabolisms. Meanwhile, combined exposure of PVC/PP and Cd increased the abundance of intestinal Proteobacteria and pathogen Vibrio, and decreased the abundance of Gemmobacter. These changes indrectly promoted the synergistic toxicity of PVC/PP and Cd through metabolites, such as indole-3-pyruvate (IPyA), chenodeoxycholic acid (CDCA), and cholic acid (CA). These findings highlighted that more attention should be paid to the toxicity of chemicals at environmentally relevant concentrations, particularly those co-existing with MPs.

The iodinated contrast agent diatrizoic acid has an impact on the metabolome of the mollusc Dreissena polymorpha

The occurrence of iodinated contrast agents (ICAs) in the aquatic environment is relatively well documented, showing that these compounds can be found at several µg/L in natural waters, and up to hundreds of µg/L in waste water treatment plants inlets. Nevertheless, only few studies address their potential impacts and fate in aquatic organisms mainly because these compounds are considered non-toxic due to their intrinsic properties. However, as aquatic organisms are continuously exposed to these compounds, they could nonetheless induce some adverse effects on aquatic populations like filter feeder organisms. To verify this, we exposed model organisms, Dreissena polymorpha mollusks, to 100 µg/L of an ICA, diatrizoic acid (DTZ), to determine the potential biological effects caused by this compound using a non-targeted metabolomic approach based on liquid chromatography coupled to high resolution mass spectrometry. Metabolic profiles showed a slight effect of DTZ, with some metabolome variations linked to exposure. Indeed, to avoid any misinterpretation of DTZ effects, we also studied the natural evolution of the metabolome over time in unexposed mussels, showing that control mussels exhibited metabolomic changes over the exposure period. During DTZ exposure, we showed that the carnitine shuttle pathway of fatty acids and pyrimidine metabolisms were impacted, leading to dysregulation of mussels’ energy metabolism. Thus, this study demonstrates for the first time that compounds considered non-toxic like ICAs can have an impact on aquatic organisms such as bivalves by slightly modulating their metabolome.

Assessing the ecotoxicological effects of novel cellulose nanocrystalline glitter compared to conventional polyethylene terephthalate glitter: Toxicity to springtails (Folsomia candida)

Glitter is a type of microplastic, and thus there is a need to assess its potential impacts on the environment and to assess the potential for non-plastic cellulose nanocrystal structurally colored glitters as safe and sustainable replacements. The ecotoxicity of glitter has been mostly ignored in the research literature, with only a few published studies focusing on aquatic organisms. Therefore, an exposure experiment was conducted to examine the impact of conventional polyethylene terephthalate (PET) glitter as well as untreated and heat-treated cellulose nanocrystal (CNC) based glitter on the survival, reproduction, and length of Folsomia candida (springtail). Folsomia candida reproduction was reduced by 61% (P = 0.013) after exposure to PET glitter at 1000 mg/kg, while no significant effects were observed on F. candida survival and length. In contrast, there were no significant impacts on F. candida survival, length, or reproduction when exposed to untreated or heat-treated CNC glitter. These results indicate that exposure to PET glitter may impact soil invertebrates at the population level, and that CNC glitter has potential as a biodegradable non-plastic alternative to PET glitter to decrease detrimental effects on soil ecosystems.

Merkel cells and corpuscles of Stannius as putative targets for polyethylene terephthalate microfibers in sheepshead minnow larvae

Polyethylene terephthalate (PET) fibers are contaminated in wastewater from various primary sources, such as washing textile waters. PET fibers in the environment can be degraded into microfibers because of weathering processes such as sunlight, physical wear, and heat. Although recent studies reported adverse effects of PET microfibers on aquatic organisms, the lack of information on their toxicity and mode of action hampers the risk assessment of PET microfibers. Therefore, this study aimed to investigate the biological effects of PET microfibers and their underlying mechanisms in early-staged sheepshead minnows (Cyprinodon variegatus). PET microfibers (about 13 μm diameter × 106 μm length) were prepared by cutting PET threads and treated to sheepshead minnow larvae at 10 and 100 mg/L for 10 days. No acute toxicity was found in the minnow, but PET microfibers significantly produced reactive oxygen species and reduced behavioral responses of traveled distance and maximum velocity. The transcriptomic data suggested that Merkel cells (flow sensors) and corpuscles of Stannius (calcium regulator) are putative targets, which were derived from oxidative stress, sensory neuropathy, cognitive impairment, and movement disorders. These findings underscore that although PET microfibers are not directly lethal to sheepshead minnows, they could impact their survival by damaging swimming-related key genes. This study provides new insights into how PET microfibers are toxic to aquatic organisms and disrupt ecosystems beyond survival and pathological changes.