Exposure Of Aquatic Organisms Research Articles

Effects of Erythromycin on Nereis succinea and the Intestinal Microbiome across Different Salinity Levels.

The exposure of aquatic organisms to pollutants often occurs concomitantly with salinity fluctuations. Here, we reported the effects of erythromycin (0.250, 7.21, and 1030 μg/L) on marine invertebrate N. succinea and its intestinal microbiome under varying salinity levels (5‰, 15‰, and 30‰). The salinity elicited significant effects on the growth and intestinal microbiome of N. succinea. The susceptibility of the intestinal microbiome to erythromycin increased by 8.7- and 6.2-fold at salinities of 15‰ and 30‰, respectively, compared with that at 5‰ salinity. Erythromycin caused oxidative stress and histological changes in N. succinea intestines, and inhibited N. succinea growth in a concentration-dependent manner under 30‰ salinity with a maximum inhibition of 25%. At the intestinal microbial level, erythromycin enhanced the total cell counts at 5‰ salinity but reduced them at 15‰ salinity. Under all tested salinities, erythromycin diminished the antibiotic susceptibility of the intestinal microbiome. Two-way ANOVA revealed significant interactive effects (p < 0.05) between salinity and erythromycin on various parameters, including antibiotic susceptibility and intestinal microbial diversity. The present findings demonstrated the significant role of salinity in modulating the impacts of erythromycin, emphasizing the necessity to incorporate salinity fluctuations into environmental risk assessments.

Histopathological, physiological, and multi-omics insights into the hepatotoxicity mechanism of nanopolystyrene and/or diclofenac in Mylopharyngodon piceus

Nanopolystyrene (NP) and diclofenac (DCF) are common environmental contaminants in the aquatic ecosystem; therefore, the present study aimed to investigate the hepatotoxicity of NP and/or DCF exposure on aquatic organisms and the underlying mechanisms. Juvenile Mylopharyngodon piceus were used as a model organism to study the effects of NP and/or DCF exposure at environmentally relevant concentrations for 21 days. Subchronic exposure to NP and/or DCF resulted in liver histological damage. In the NP group, the presence of large lipid droplets was observed, whereas the DCF group exhibited marked hepatic sinusoidal dilatation accompanied by inflammation. Additionally, this exposure induced liver oxidative stress, as evidenced by the changes in several physiological parameters, including catalase (CAT), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), reactive oxygen species (ROS), and malondialdehyde (MDA). Integrated transcriptomic and metabolomic analysis was performed to further investigate the molecular mechanism underlying hepatotoxicity. Multi-omics analysis demonstrated, for the first time to our knowledge, that NP induced hepatic steatosis mainly through activating the glycerol-3-phosphate pathway and inhibiting VLDL assembly by targeting several key enzyme genes including GPAT, DGAT, ACSL, APOB, and MTTP. Furthermore, NP exposure disrupted arachidonic acid metabolism, which induced the release of inflammatory factors and inhibited the release of anti-inflammatory factors, ultimately causing liver inflammation in M. piceus. In contrast, DCF induced interleukin production and downregulated KLF2, causing hepatic sinusoidal dilatation with inflammation in juvenile M. piceus, which is consistent with the finding of JAK–STAT signaling pathway activation. In addition, the upregulated AMPK signaling pathway in the DCF group suggested perturbation of energy metabolism. Collectively, these findings provide novel insights into the molecular mechanism of the multiple hepatotoxicity endpoints of NP and/or DCF exposure in aquatic organisms.

The Effect of Malathion Concentration and Exposure Time on Histopathological Changes in the Liver and Gill of Rainbow Trout

Exposure of aquatic organisms to organophosphorus pollutants is a subject of keen interest to biologists and environmental scientists. Examining histopathological changes in the tissues of exposed animals can provide great insights to understand the health condition of the organisms. This study examined the effects of malathion concentration and exposure time on the liver and gill tissues of the rainbow trout (Oncorhynchus mykiss) in a laboratory condition and tried to provide a quantitative assessment for the analysis of these effects. The experiment was conducted in three treatments including 0.025, 0.05, and 0.075 mg/L of malathion for 1, 5, and 9 days with a nonexposed group as control, in three replicates. The liver and gill samples were fixed in buffered formalin. About 5 µ tissue sections were prepared using the conventional histological methods and stained using the hematoxylin–eosin method. Histopathological changes in the liver and gill tissues were quantified by grading and the resulting data were analyzed by rank-based estimation. The results showed that histopathological changes in the liver and gill tissues are more affected by the malathion concentration than by the duration of the exposure. However, longer exposure had an intensifying effect on the tissue damage caused by the malathion at higher concentrations. The presence of melanomacrophages as an indicator of malathion toxicity was determined. The fish exposed to 0.075 mg/L malathion for 9 days showed atrophy in the liver and gill tissues, indicating cell death and functional inactivation. Histopathological changes in the liver and gills confirmed the dose-dependent effect of malathion on the rainbow trout.

Concepts on Accumulation of Pesticides and Veterinary Drugs in Fish: A Review with Emphasis in Tilapia.

The quality of the aquatic environment can be compromised by the practice of intensive use of pesticides in agriculture and by the misuse of veterinary drugs. Therefore, organisms that live in aquatic ecosystems may be affected due to the presence of these chemicals, through runoff, leaching and other processes. Exposure of aquatic organisms to these xenobiotics could pose health risks. Consequently, there is a growing interest in predicting the bioaccumulation of these substances in aquatic biota from experiments conducted under laboratory conditions. Studies on fish have been performed due to its importance as human food and their wide distribution in most of the aquatic environment. Thus, this article reviews the concepts on determining the accumulation of pesticides and veterinary drugs in fish. The risk regarding the consumption of fish containing residues of these chemical agents, the acceptable daily intake, the testing protocols and the analytical techniques used to determine the residues of these substances in fish tissues are discussed. An emphasis on studies involving tilapia as the test organism was included because, according to Food and Agricultural Organization (FAO), this species is one of the most cultivated in the world.

Carassius auratus as a bioindicator of the health status of Lake Trasimeno and risk assessment for consumers.

Fish are good bio-indicators of the health status of the aquatic environment and can be used as biomarkers to assess the aquatic behavior of environmental pollutants, the exposure of aquatic organisms, and the health risk for consumers. Goldfish are a significant bioindicator in the Lake Trasimeno aquatic system (Umbria, Italy). This study aimed to characterize the health status and the chemical and biotic contamination of Lake Trasimeno to define its anthropogenic and natural pressures and the risk associated with consuming its fishery products. 114 determinations were performed on Carassius auratus samples from 2018 to 2020, and the occurrence of brominated flame retardants, non-dioxin-like polychlorinated biphenyls, heavy metals, and microplastics was analytically investigated. Dietary exposure assessment, risk characterization, and benefit-risk evaluation were performed for schoolchildren from 3 to 10 years old. Flame-retardants registered high levels of non-detects (99% for polybrominated diphenyl ether and 76% for hexabromocyclododecanes), while polychlorinated biphenyls were found in all samples with a maximum level of 56.3 ng/g. Traces of at least one heavy metal were found in all samples, though always below the regulatory limit. Microplastics were found with a 75% frequency of fish ingesting at least one particle. Dietary exposure and risk characterization reveal negligible contributions to the reference values of all contaminants, except for mercury, which reached up to 25% of admissible daily intake. The benefit- risk assessment highlighted that the benefits of freshwater fish intake outweigh the associated risks. The examination of goldfish as indicator fish reveals the quality of Lake Trasimeno's aquatic environment and the safety of its products.

Exposure of aquatic organisms to natural radionuclides in irrigation drains, Qena, Egypt

Natural radioactivity in irrigation drains was measured by gamma spectrometry, and the resulting dose rates received by aquatic organisms were estimated. Irrigation water and sediment samples were collected from 5 irrigation drains located in Qena governorate, south of Egypt. The average activity concentrations (Bq L−1) of 226Ra, 232Th, and 40 K in irrigation water were 0.76 ± 0.06, 0.27 ± 0.02, and 8.14 ± 0.71, while in sediment (Bq kg−1) were 24.46 ± 1.84, 20.72 ± 1.45, and 453.00 ± 28.14, respectively. The total dose rate per aquatic organism ranged from 1.94 × 10–04 µGy h−1 in Mollusc to 7.15 × 10–04 µGy h−1 in phytoplankton. These values are far from the international recommended limit 400 µGy h−1 for chronic exposure to aquatic organisms, and the dose rate screening value of 10 µGy h−1 suggested by ERICA tool. Based on these results, it is unlikely that harmful effects will appear on the considered aquatic organisms due to exposure to natural radioactivity in the studied environment.

Freely dissolved concentration profile and Hyalella azteca toxicity of cationic surfactant C12-benzalkonium in spiked-sediment toxicity test

The freely dissolved concentrations (Cfree) have been considered a useful metric for exposure of aquatic organisms to organic contaminants. However, Cfree for cationic surfactants has rarely been measured, and its use in sediment toxicity tests has not been evaluated. In this study, Cfree of the cationic surfactant benzyldodecyldimethylammonium (C12-benzalkonium; C12-BAC) in water-only and spiked-sediment toxicity tests with the amphipod Hyalella azteca was analyzed using a passive sampling method. Polyacrylate-coated glass fibers were adopted as the passive sampler. Sorption isotherms of C12-BAC to the polyacrylate fibers were measured in chemical conditions comparable to those of the toxicity tests and used for Cfree calculation in both tests. Detailed concentration analysis in the sediment toxicity test demonstrated a high concentration gradient of C12-BAC between sediment and overlying water; Cfree in pore water was 17–78 times higher than Cfree in overlying water and was 7.2–13 times higher than Cfree at the sediment–water interface. The 50 % lethal concentration and bioconcentration factor of H. azteca obtained in the water-only test (23 μg/L and 140 ± 70 L/kg-wet, respectively) agreed with those calculated based on Cfree in pore water in the sediment test (49 μg/L and 140 ± 90 L/kg-wet, respectively), indicating that H. azteca is exposed mainly to the freely dissolved fraction in pore water. We concluded that Cfree in pore water is a useful exposure metric for H. azteca to cationic surfactants.

Comparative evaluation on the toxic effect of silver (Ag) and zinc oxide (ZnO) nanoparticles on different trophic levels in aquatic ecosystems: A review.

Silver (Ag) and zinc oxide (ZnO) are considered to be harmful nanoparticles (NPs) to the aquatic organisms as their intake causes toxic impacts to wildlife, through direct ingestion or by the transference along trophic levels. Over usage and ultimate disposal of metallic particles from the industries subsequently lead to pollution of the aquatic environment. Exposure of NPs in aquatic ecosystem alters biological and physicochemical parameters of the water and aquatic organisms and determines their potential ecotoxicological impacts. Prolonged exposure of aquatic organisms to these NPs results in differential bioaccumulation and distribution into internal organs like liver, kidney, gills, brain, and muscle tissue. The contact of NPs to aquatic organisms induces various types of toxic traits including cytotoxicity, genotoxicity, and epigeneticity. Taking this in consideration, this present review focuses on the comparative toxic impact of ZnO and Ag NPs towards both vertebrates and invertebrates in aquatic ecosystems.

Survival analysis of African catfish and Nile tilapia briefly exposed to complex pesticide mixtures

BackgroundPulse exposures are the consequences of the intermittent release of pollutants in the environment. Brief exposure of aquatic organisms to high concentrations of pesticides simultaneously occurs, particularly in small watercourses during high flows. The effects of pulse exposure often include effects occurring during and after the exposure. Despite this, routine toxicity tests procedures often ignore brief exposure scenarios and the role of time in toxicity. We conducted a pulse toxicity test by briefly exposing African catfish and Nile tilapia fingerlings to pesticide mixtures of atrazine, mancozeb, chlorpyrifos, and lambda-cyhalothrin. The study aimed to estimate pesticide mixture interaction in pulse-exposed fish and elucidate the influence of species differences on the response of fish to the pesticide mixture.ResultsDespite the similarity in fingerlings weight, African catfish had a significantly higher survival probability than Nile tilapia after exposure to atrazine-mancozeb mixture. However, the survival probability of African catfish and Nile tilapia fingerlings were similar after exposure to atrazine-chlorpyrifos, atrazine-lambda cyhalothrin, mancozeb-chlorpyrifos, mancozeb-lambda cyhalothrin, chlorpyrifos-lambda cyhalothrin, and quaternary mixture (p > 0.05). The survival probability of exposed fingerlings was significantly lower for continuous than pulse exposure to the mixtures (p < 0.01). Nevertheless, the survival probability of 60 min of pulse exposure to 13.49 mg/L mancozeb-lambda cyhalothrin was similar to continuous exposure for 96 h. Atrazine-mancozeb, atrazine-chlorpyrifos, atrazine-lambda cyhalothrin, mancozeb-chlorpyrifos, mancozeb-lambda cyhalothrin, and the quaternary pesticide mixture were antagonists in African catfish but not in Nile tilapia. At the same time, chlorpyrifos-lambda-cyhalothrin was antagonistic in Nile tilapia but not African catfish.ConclusionsPesticide mixture interaction was antagonist but specie-dependent. Innate intrinsic and extrinsic deterministic factors and, to a limited extent, stochastic processes may have influenced the survival probability of African catfish, and Nile tilapia pulsed exposed to complex pesticide mixtures. Pulse toxicity assessment using survival analysis is relevant in ecotoxicology as it enables the study of factors that can influence pulse toxicity.

Developmental toxicity of fenbuconazole in zebrafish: Effects on mitochondrial respiration and locomotor behavior

Triazole fungicides are used to control the disease of cereal crops but may also cause adverse effects on non-target organisms. There is a lack of toxicity data for some triazoles such as fenbuconazole in aquatic organisms. This research was conducted to evaluate the toxicity of fenbuconazole at environmentally relevant concentrations with attention on the mitochondria, antioxidant system, and locomotor activity in zebrafish. Zebrafish were exposed to one concentration of 5, 50, 200 or 500 ng/L fenbuconazole for 96 h. There was no effect on survival nor percentage of fish hatched, but exposure to 200 and 500 ng/L fenbuconazole resulted in malformation and hypoactivity in zebrafish. Oxygen consumption rates (OCR) of embryos were measured to determine if the fungicide impaired mitochondrial respiration. Exposure to 500 ng/L fenbuconazole reduced basal OCR and oligomycin-induced ATP linked respiration in exposed fish. Fenbuconazole reduced mitochondrial membrane potential and reduced the activities of mitochondrial Complex II and III. Transcript levels of both sdhc and cyc1, each related to Complex II and III, were also altered in expression by fenbuconazole exposure, consistent with mitochondrial dysfunction in embryos. Fenbuconazole activated the antioxidant system, based upon both transcriptional and enzymatic data in zebrafish. Consistent with mitochondrial impairment, molecular docking confirmed a strong binding capacity of the fungicide at the Qi site of Complex III, revealing this complex is susceptible to fenbuconazole. This study reveals potential toxicity pathways related to fenbuconazole exposure in aquatic organisms; such data can improve risk assessments for triazole fungicides.

Exposure duration and composition are important variables to predict short-term toxicity of effluents to a tropical copepod, Acartia sinjiensis

Predicting the toxicity of effluent exposures, which vary in duration, composition, and concentration, poses a challenge for ecological risk assessments. Effluent discharges may frequently result in the exposure of aquatic organisms to high concentrations of mixed contaminants for short durations. In the receiving environment effluents will undergo dilution and physical or chemical processes that further reduce contaminant concentrations at varying rates. To date, most studies comparing toxicity risks of continuous and pulsed contaminant exposures have focused on individual contaminants. In this study, the toxicity to the tropical euryhaline copepod Acartia sinjiensis of two complex effluents was assessed, comparing 6- and 18-h pulses and 78-h continuous exposures. Observations of larval development success and population size were completed after a 78-h incubation period, to observe for latent effects after pulse exposures. The chemical compositions of the effluents were assessed over time and different contaminants (i.e., metals, ammonia or organics) declined at differing rates. These were characterized as either a minimal, steady, or rapid decline. Nauplii development and population after 78 h were more impacted by effluent exposures following an 18-h pulse, compared to a 6-h pulse. Based on pulse-exposure concentrations, the 50% effect concentrations (EC50) were similar for continuous and 18-h exposures but up to 3-fold greater (lower toxicity) for the shorter 6-h exposures. Time-weighted average concentrations did not accurately predict toxicity from pulse exposures of the effluents. Concentration-addition toxicity modelling using toxicity data from pulse exposures of single contaminants was useful for predicting the toxicity of chemical mixtures exposed for varying durations. Recommendations for modified approaches to assessing risks of short-term effluent discharges are discussed.

Watershed-Scale Risk to Aquatic Organisms from Complex Chemical Mixtures in the Shenandoah River.

River waters contain complex chemical mixtures derived from natural and anthropogenic sources. Aquatic organisms are exposed to the entire chemical composition of the water, resulting in potential effects at the organismal through ecosystem level. This study applied a holistic approach to assess landscape, hydrological, chemical, and biological variables. On-site mobile laboratory experiments were conducted to evaluate biological effects of exposure to chemical mixtures in the Shenandoah River Watershed. A suite of 534 inorganic and organic constituents were analyzed, of which 273 were detected. A watershed-scale accumulated wastewater model was developed to predict environmental concentrations of chemicals derived from wastewater treatment plants (WWTPs) to assess potential aquatic organism exposure for all stream reaches in the watershed. Measured and modeled concentrations generally were within a factor of 2. Ecotoxicological effects from exposure to individual components of the chemical mixture were evaluated using risk quotients (RQs) based on measured or predicted environmental concentrations and no effect concentrations or chronic toxicity threshold values. Seventy-two percent of the compounds had RQ values <0.1, indicating limited risk from individual chemicals. However, when individual RQs were aggregated into a risk index, most stream reaches receiving WWTP effluent posed potential risk to aquatic organisms from exposure to complex chemical mixtures.

Marine Neurotoxins’ Effects on Environmental and Human Health: An OMICS Overview

Harmful algal blooms (HAB), and the consequent release of toxic metabolites, can be responsible for seafood poisoning outbreaks. Marine wildlife can accumulate these toxins throughout the food chain, which presents a threat to consumers’ health. Some of these toxins, such as saxitoxin (STX), domoic acid (DA), ciguatoxin (CTX), brevetoxin (BTX), tetrodotoxin (TTX), and β-N-methylamino-L-alanine (BMAA), cause severe neurological symptoms in humans. Considerable information is missing, however, notably the consequences of toxin exposures on changes in gene expression, protein profile, and metabolic pathways. This information could lead to understanding the consequence of marine neurotoxin exposure in aquatic organisms and humans. Nevertheless, recent contributions to the knowledge of neurotoxins arise from OMICS-based research, such as genomics, transcriptomics, proteomics, and metabolomics. This review presents a comprehensive overview of the most recent research and of the available solutions to explore OMICS datasets in order to identify new features in terms of ecotoxicology, food safety, and human health. In addition, future perspectives in OMICS studies are discussed.

Pre-fertilization exposure of sperm to nano-sized plastic particles decreases offspring size and swimming performance in the European whitefish (Coregonus lavaretus)

Exposure of aquatic organisms to micro- and nano-sized plastic debris in their environment has become an alarming concern. Besides having a number of potentially harmful impacts for individual organisms, plastic particles can also influence the phenotype and performance of their offspring. We tested whether the sperm pre-fertilization exposure to nanoplastic particles could affect offspring survival, size, and swimming performance in the European whitefish Coregonus lavaretus. We exposed sperm of ten whitefish males to three concentrations (0, 100 and 10 000 pcs spermatozoa−1) of 50 nm carboxyl-coated polystyrene spheres, recorded sperm motility parameters using computer assisted sperm analysis (CASA) and then fertilized the eggs of five females in all possible male-female combinations. Finally, we studied embryonic mortality, hatching time, size, and post-hatching swimming performance of the offspring. We found that highest concentration of plastic particles decreased sperm motility and offspring hatching time. Furthermore, sperm exposure to highest concentration of plastics reduced offspring body mass and impaired their swimming ability. This suggests that sperm pre-fertilization exposure to plastic pollution may decrease male fertilization potential and have important transgenerational impacts for offspring phenotype and performance. Our findings indicate that nanoplastics pollution may have significant ecological and evolutionary consequences in aquatic ecosystems.

In vivo exposure of marine mussels to venlafaxine: bioconcentration and metabolization.

Pharmaceuticals are present in natural waters, thus contributing to the general exposure of aquatic organisms, but few data are available on the accumulation of these substances in marine organisms. The present study evaluated the in vivo bioconcentration of an antidepressant-venlafaxine (VLF)-in marine mussels (Mytilus galloprovincialis) during 7 days of exposure at nominal 10 μg/L concentration, followed by a 7-day depuration period. The bioconcentration factor (BCF) was 265 mL/g dry weight (dw). VLF accumulation reached an average tissue concentration of 2146 ± 156 ng/g dw within 7 days, showing a first-order kinetics process. N-desmethylvenlafaxine (N-VLF) and O-desmethylvenlafaxine (O-VLF) metabolites were quantified in mussel tissues, whereas N,N-didesmethylvenlafaxine (NN-VLF) was only recorded as being detected. These three metabolites were also quantified in water, indicating an active metabolism and VLF excretion in Mediterranean mussels. Complementary experiments conducted at nominal concentrations of 1, 10, and 100 μg/L for 7 days confirmed the VLF bioconcentration and metabolism and allowed us to quantify a supplementary metabolite, i.e., N,O-didesmethylvenlafaxine (NO-VLF), in mussel tissues. These results encourage further research on a more complete characterization of metabolism and on any disturbances linked to bioconcentration of VLF on bivalves.

COVID-19 Treatment Agents: Do They Pose an Environmental Risk?

The end of 2019 was marked by reports of a previously unknown virus causing coronavirus disease 19 (COVID-19). With over 800 new daily hospitalizations at the peak in Los Angeles (LA) County, the potential for high use of COVID-19 treatment agents, remdesivir and dexamethasone, warranted a screening assessment of their fate and toxicity risk for aquatic organisms. We predicted environmental concentrations (PECs) using the ChemFate model and hospitalizations data and compared them to predicted ecotoxicity concentrations generated using Ecological Structure Activity Relationships (ECOSAR) to assess risk to potentially exposed organisms. The lowest predicted toxicity thresholds were between 2 and 11 orders of magnitude greater than the highest PECs for freshwater and saltwater. We conclude that had all eligible patients in LA County been given the recommended treatment regimen, exposure of aquatic organisms in regional water bodies to remdesivir, dexamethasone, and their evaluated metabolites would not be likely to be affected based on ECOSAR predictions. Conservative, protective assumptions were used for this screening analysis, considering limited toxicity information. Modeling tools thus serve to predict environmental concentrations and estimate ecotoxicity risks of novel treatment agents and can provide useful preliminary data to assess and manage ecological health risks.

Comparison of the effects of continuous and accumulative exposure to nanoplastics on microalga Chlorella pyrenoidosa during chronic toxicity

Most previous studies have focused on the continuous exposure of aquatic organisms to nanoplastics. However, persistent pollutants in natural aquatic surroundings are a threat, and their concentrations are continuously increasing. The discussion and research into the effects of accumulative exposure to these materials are limited. Therefore, this study aimed to compare the effects of continuous and accumulative exposure to polystyrene (PS) nanoplastics (80 nm) on Chlorella pyrenoidosa during chronic toxicity. The results indicated that under conditions of continuous exposure, this alga exhibited self-recovery to defend against the negative effects of PS nanoplastics during 15–21 days of exposure (the 21-d inhibitory rate was 1.41%). However, one unanticipated finding was that during the same period of accumulative exposure, nanoplastics retained a substantial and stable inhibitory effect on the algal growth (the 21-d inhibitory rate was 6.79% in accumulative exposure for twice), indicating the invalid self-recovery of algae. The results of scanning electron microscopy demonstrated that on day 21, the degree of damage to the algal cells under accumulative exposure was more severe than that under continuous exposure. Hence, nanoplastics exerted an irreversibly negative effect on aquatic organisms depending on the pattern, frequency, concentration, and duration of exposure. This project evaluated the practical significance of nanoplastics in aquatic ecosystems.

Graphene oxide and reduced graphene oxide promote the effects of exogenous T3 thyroid hormone in the amphibian Xenopus laevis

The interest for graphene-based nanomaterials (GBMs) is growing worldwide as their properties allow the development of new innovative applications. In parallel, concerns are increasing about their potential adverse effects on the environment are increasing. The available data concerning the potential risk associated to exposure of aquatic organisms to these GBMs are still limited and little is known regarding their endocrine disruption potential. In the present study, the endocrine disruption potential of graphene oxide (GO) and reduced graphene oxide (rGO) was assessed using a T3-induced amphibian metamorphosis assay. The results indicated that GBMs potentiate the effects of exogenous T3 with a more marked effect of GO compared to rGO. T3 quantifications in the exposure media indicated adsorption of the hormone on GBMs, increasing its bioavailability for organisms because GBMs are accumulated in the gut and the gills of these amphibians. This study highlights that the tested GBMs do not disrupt the thyroid pathway in amphibians but indicates that adsorption properties of these nanomaterials may increase the bioavailability and the toxicity of other pollutants.

Elucidating venlafaxine metabolism in the Mediterranean mussel (Mytilus galloprovincialis) through combined targeted and non-targeted approaches.

Exposure of aquatic organisms to antidepressants is currently well documented, while little information is available on how wild organisms cope with exposure to these pharmaceutical products. Studies on antidepressant metabolism in exposed organisms could generate information on their detoxification pathways and pharmacokinetics. The goal of this study was to enhance knowledge on the metabolism of venlafaxine (VEN)-an antidepressant frequently found in aquatic ecosystems-in Mytilus galloprovincialis, a bivalve that is present worldwide. An original tissue extraction technique based on the cationic properties of VEN was developed for further analysis of VEN and its metabolites using targeted and non-targeted approaches. This extraction method was assessed in terms of recovery and matrix effects for VEN metabolites. Commercial analytical standards were applied to characterize metabolites found in mussels exposed to 10μg/L VEN for 3 and 7days. Targeted and non-targeted approaches using liquid chromatography (LC) combined with high-resolution mass spectrometry (HRMS) were implemented to screen for expected metabolites based on the literature on aquatic species, and for metabolites not previously documented. Four venlafaxine metabolites were identified, namely N-desmethylvenlafaxine and O-desmethylvenlafaxine, which were clearly identified using analytical standards, and two other metabolites revealed by non-target analysis. According to the signal intensity, hydroxy-venlafaxine (OH-VEN) was the predominant metabolite detected in mussels exposed for 3 and 7days.

Salinity Changes the Dynamics of Pyrethroid Toxicity in Terms of Behavioral Effects on Newly Hatched Delta Smelt Larvae.

Salinity can interact with organic compounds and modulate their toxicity. Studies have shown that the fraction of pyrethroid insecticides in the aqueous phase increases with increasing salinity, potentially increasing the risk of exposure for aquatic organisms at higher salinities. In the San Francisco Bay Delta (SFBD) estuary, pyrethroid concentrations increase during the rainy season, coinciding with the spawning season of Delta Smelt (Hypomesus transpacificus), an endangered, endemic fish. Furthermore, salinity intrusion in the SFBD is exacerbated by global climate change, which may change the dynamics of pyrethroid toxicity on aquatic animals. Therefore, examining the effect of salinity on the sublethal toxicity of pyrethroids is essential for risk assessments, especially during the early life stages of estuarine fishes. To address this, we investigated behavioral effects of permethrin and bifenthrin at three environmentally relevant concentrations across a salinity gradient (0.5, 2 and 6 PSU) on Delta Smelt yolk-sac larvae. Our results suggest that environmentally relevant concentrations of pyrethroids can perturb Delta Smelt larvae behavior even at the lowest concentrations (<1 ng/L) and that salinity can change the dynamic of pyrethroid toxicity in terms of behavioral effects, especially for bifenthrin, where salinity was positively correlated with anti-thigmotaxis at each concentration.