Behavioural and transcriptional changes in the amphipod Echinogammarus marinus exposed to two antidepressants, fluoxetine and sertraline

Detection of 10 commonly used pharmaceuticals in reef-building stony corals from shallow (5-12 m) and deep (30-40 m) sites in the Red Sea

Although pharmaceutically-active compounds (PhACs) are increasingly being found to be present in marine environments, their presence in coral reefs, already under threat from various stressors, has remains unexplored. This study focused on PhAC presence in two stony-coral genera, collected from different depths and sites in the Red Sea. The findings reveal the presence of ten different PhACs, with elevated concentrations detected in corals from shallow sites and in areas with heavy human activity. Notably, all samples contained at least one PhAC, with the antibiotic sulfamethoxazole being the most prevalent compound, detected in 93% of the samples, at concentrations ranging from 1.5 to 2080 ng/g dry weight (dw) tissue, with an average concentration of 106 ng/g dw. These findings underscore the urgent need for conservation initiatives aimed at protecting coral-reef ecosystems from the escalating threat of anthropogenic contamination, including such potential risks as the development of antibiotic resistance in marine organisms and the disruption of critical spawning synchrony among coral populations.

Evaluating non-monotonic dose-response relationships in ecotoxicological risk assessment: A case study based on a systematic review of data on fluoxetine

The environmental presence of pharmaceuticals, including the antidepressant fluoxetine, has become a subject of concern. Numerous studies have revealed effects of fluoxetine at environmental concentrations. Some of these studies have reported non-monotonic dose-response curves (NMDRs), leading to discussion because of the inconsistent detection of subtle effects and lack of mechanistic understanding. Nevertheless, investigating NMDRs in risk assessment is important, because neglecting them could underestimate potential risks of chemicals at low levels of exposure. Identification and quantification of NMDRs in risk assessment remains challenging, particularly given the prevalence of single outliers and the lack of sound statistical analyses. In response, the European Food Safety Authority (Beausoleil et al., 2016) presented a framework delineating six checkpoints for the evaluation of NMDR datasets, offering a systematic method for their assessment. The present study applies this framework to the case study of fluoxetine, aiming to assess the weight-of-evidence for the reported NMDR relationships. Through a systematic literature search, 53 datasets were selected for analysis against the six checkpoints. The results reveal that while a minority of these datasets meet all checkpoints, a significant proportion (27%) fulfilled at least five. Notably, many studies did not meet checkpoint 3, which requires NMDRs to be based on more than a single outlier. Overall, the current study points out a number of studies with considerable evidence supporting the presence of NMDRs for fluoxetine, while the majority of studies lacks strong evidence. The suggested framework proved useful for analysing NMDRs in ecotoxicological studies, but it is still imperative to develop further understanding of their biological plausibility.

Effect of an antidepressant on aquatic ecosystems in the presence of microplastics: A mesocosm study

Emerging pollutants, such as pharmaceuticals and microplastics have become a pressing concern due to their widespread presence and potential impacts on ecological systems. To assess the ecosystem-level effects of these pollutants within a multi-stressor context, we simulated real-world conditions by exposing a near-natural multi-trophic aquatic food web to a gradient of environmentally relevant concentrations of fluoxetine and microplastics in large mesocosms over a period of more than three months. We measured the biomass and abundance of different trophic groups, as well as ecological functions such as nutrient availability and decomposition rate. To explore the mechanisms underlying potential community and ecosystem-level effects, we also performed behavioral assays focusing on locomotion parameters as a response variable in three species: Daphnia magna (zooplankton prey), Chaoborus flavicans larvae (invertebrate pelagic predator of zooplankton) and Asellus aquaticus (benthic macroinvertebrate), using water from the mesocosms. Our mesocosm results demonstrate that presence of microplastics governs the response in phytoplankton biomass, with a weak non-monotonic dose-response relationship due to the interaction between microplastics and fluoxetine. However, exposure to fluoxetine evoked a strong non-monotonic dose-response in zooplankton abundance and microbial decomposition rate of plant material. In the behavioral assays, the locomotion of zooplankton prey D. magna showed a similar non-monotonic response primarily induced by fluoxetine. Its predator C. flavicans, however, showed a significant non-monotonic response governed by both microplastics and fluoxetine. The behavior of the decomposer A. aquaticus significantly decreased at higher fluoxetine concentrations, potentially leading to reduced decomposition rates near the sediment. Our study demonstrates that effects observed upon short-term exposure result in more pronounced ecosystem-level effects following chronic exposure.

Changes in Induced-Antipredation Defense Traits and Transcriptome Regulations of Daphnia magna in Response to 5-HT1A Receptor Antagonist

The serotonin signaling system plays a crucial role in regulating the ontogeny of crustaceans. Here, we describe the effects of different concentrations of the 5-hydroxytryptamine 1A receptor antagonist (WAY-100635) on the induced antipredation (Rhodeus ocellatus as the predator), morphological, behavioral, and life-history defenses of Daphnia magna and use transcriptomics to analyze the underlying molecular mechanisms. Our results indicate that exposure to WAY-100635 leads to changes in the expression of different defensive traits in D. magna when faced with fish predation risks. Specifically, as the length of exposure to WAY-100635 increases, high concentrations of WAY-100635 inhibit defensive responses associated with morphological and reproductive activities but promote the immediate negative phototactic behavioral defense of D. magna. This change is related to the underlying mechanism through which WAY-100635 interferes with gene expression of G-protein-coupled GABA receptors by affecting GABBR1 but promotes serotonin receptor signaling and ecdysteroid signaling pathways. In addition, we also find for the first time that fish kairomone can significantly activate the HIF-1α signaling pathway, which may lead to an increase in the rate of immediate movement. These results can help assess the potential impacts of serotonin-disrupting psychotropic drugs on zooplankton in aquatic ecosystems.

Antidepressants - The new endocrine disruptors? The case of crustaceans

Antidepressants are high-volume pharmaceuticals that accumulate to concentrations in the μg·L-1 range in surface waters. The release of peptide hormones via neurosecretory cells appears as a natural target for antidepressants. Here I review research that suggests that antidepressants indeed disrupt endocrine signalling in crustaceans, by acting on the synthesis and release of neurohormones, such as crustacean hyperglycaemic hormone, moult inhibiting hormone and pigment dispersing hormone in decapods, as well as methyl farnesoate in Daphnids. Hence, antidepressants can affect hormonal regulation of physiological functions: increase in energy metabolism and activity, lowered ecdysteroid levels, potentially disrupting moult and somatic growth, reducing colour change capacity and compromising camouflage, as well as induction of male sex determination. Several studies further suggest effects of antidepressants on crustacean reproduction, but the hormonal regulation of these effects remains elusive. All things considered, a body of evidence strongly suggests that antidepressants are endocrine disrupting compounds in crustaceans.

The effects of plastic additives on swimming activity and startle response in marine amphipod Echinogammarus marinus

Plastic additives are widely used in plastic production and are found in the environment owing to their widespread applications. Among these additives, N-butyl benzenesulfonamide (NBBS) and triphenyl phosphate (TPHP) are under international watchlist for evaluation, with limited studies on amphipods. Di-ethylhexyl phthalate (DEHP) and dibutyl phthalate (DBP) are banned in some countries and categorised as substances of very high concern. This study aimed to investigate the effects of NBBS, TPHP, DEHP and DBP on the swimming activity of a coastal intertidal marine amphipod, Echinogammarus marinus. Furthermore, this study is the first to quantify startle response in E. marinus in response to light stimuli. Amphipods were exposed to 0, 0.5, 5, 50 and 500 μg/l concentrations of all test compounds. Swimming activity and startle responses were assessed by video tracking and analysis using an 8-min alternating dark and light protocol after exposure on days 7 and 14. We observed an overall compound and light effect on the swimming activity of E. marinus. A significant decrease in swimming distance was found in 500 μg/l NBBS and TPHP. We observed that the startle response in E. marinus had a latency period of >2 s and animals were assessed at 1 s and the sum of the first 5 s. There was a clear startle response in E. marinus during dark to light transition, evident with increased swimming distance. NBBS exposure significantly increased startle response at environmental concentrations, while significant effects were only seen in 500 μg/l TPHP at 5 s. We found no significant effects of DEHP and DBP on swimming behaviour at the concentrations assessed. The findings of this study affirm the necessity for a continuous review of plastic additives to combat adverse behavioural effects that may be transferable to the population levels.

Toxicokinetics of the Antidepressant Fluoxetine and Its Active Metabolite Norfluoxetine in Caenorhabditis elegans and Their Comparative Potency

The nematode Caenorhabditis elegans is a valuable model for ecotoxicological research, yet limited attention has been given to understanding how it absorbs, distributes, metabolizes, and excretes chemicals. This is crucial for C. elegans because the organism is known to have strong uptake barriers that are known to be susceptible to potential confounding effects of the presence of Escherichia coli as a food source. One frequently studied compound in C. elegans is the antidepressant fluoxetine, which has an active metabolite norfluoxetine. In this study, we evaluated the toxicokinetics and relative potency of norfluoxetine and fluoxetine in chemotaxis and activity tests. Toxicokinetics experiments were conducted with varying times, concentrations of fluoxetine, and in the absence or presence of E. coli, simulated with a one-compartment model. Our findings demonstrate that C. elegans can take up fluoxetine and convert it into norfluoxetine. Norfluoxetine proved slightly more potent and had a longer elimination half-life. The bioconcentration factor, uptake, and elimination rate constants depended on exposure levels, duration, and the presence of E. coli in the exposure medium. These findings expand our understanding of toxicokinetic modeling in C. elegans for different exposure scenarios, underlining the importance of considering norfluoxetine formation in exposure and bioactivity assessments of fluoxetine.

Elucidating the performance of UV-based photochemical processes for the removal of trace organic contaminants: Degradation and toxicity evaluation

In this study, the performance of standalone ultraviolet (UV) photolysis and UV-based advanced oxidation processes (AOPs), namely, UV/hydrogen peroxide, UV/chlorine, UV/persulphate, and UV/permonosulphate, were investigated for the degradation of 31 trace organic contaminants (TrOCs). Under the tested conditions, standalone UV photolysis did not achieve effective removal of TrOCs. To improve the degradation efficiency of UV photolysis, four different oxidants were added individually to the test solution. The effect of these oxidants in the absence of UV irradiation was also explored and only chlorine showed promising degradation of some contaminants. During the chlorination of 31 investigated TrOCs, only six demonstrated greater than 50% degradation. The combined UV-based AOPs demonstrated much improved degradation (ranging from 65 to 100%) depending on TrOC-structure and oxidant concentration. The UV/hydrogen peroxide process showed similar degradation of TrOCs, irrespective of the functional groups (i.e., electron withdrawing groups, EWGs and electron donating groups, EDGs) present in their structures. Conversely, the UV/sulphate and UV/chlorine based processes achieved better degradation of the TrOCs with EDGs in their structures. TrOCs degradation improved up to 40% when oxidants concentrations were increased from 0.1 to 1 mM, and further increasing the concentration to 2 mM did not improve degradation. Toxicity evaluation using bioluminescence test (BLT assay) demonstrated that except for UV/hydrogen peroxide, all UV-based AOPs increased the toxicity of the treated effluent, indicating generation of toxic by-products. This study elucidates the performance of four different UV-based AOPs for the removal of commonly detected diverse TrOCs for the first time.

Effects of antidepressant exposure on aquatic communities assessed by a combination of morphological identification, functional measurements, environmental DNA metabarcoding and bioassays

The antidepressant fluoxetine is frequently detected in aquatic ecosystems, yet the effects on aquatic communities and ecosystems are still largely unknown. Therefore the aim of this study is to assess the effects of the long-term application of fluoxetine on key components of aquatic ecosystems including macroinvertebrate-, zooplankton-, phytoplankton- and microbial communities and organic matter decomposition by using traditional and non-traditional assessment methods. For this, we exposed 18 outdoor mesocosms (water volume of 1530 L and 10 cm of sediment) to five different concentrations of fluoxetine (0.2, 2, 20 and 200 μg/L) for eight weeks, followed by an eight-week recovery period. We quantified population and community effects by morphological identification, environmental DNA metabarcoding, in vitro and in vivo bioassays and measured organic matter decomposition as a measure of ecosystem functioning. We found effects of fluoxetine on bacterial, algal, zooplankton and macroinvertebrate communities and decomposition rates, mainly for the highest (200 μg/L) treatment. Treatment-related decreases in abundances were found for damselfly larvae (NOEC of 0.2 μg/L) and Sphaeriidae bivalves (NOEC of 20 μg/L), whereas Asellus aquaticus increased in abundance (NOEC <0.2 μg/L). Fluoxetine decreased photosynthetic activity and primary production of the suspended algae community. eDNA assessment provided additional insights by revealing that the algae belonging to the class Cryptophyceae and certain cyanobacteria taxa were the most negatively responding taxa to fluoxetine. Our results, together with results of others, suggest that fluoxetine can alter community structure and ecosystem functioning and that some impacts of fluoxetine on certain taxa can already be observed at environmentally realistic concentrations.

Understanding the differential impacts of two antidepressants on locomotion of freshwater snails (Lymnaea stagnalis)

There is growing evidence of negative impacts of antidepressants on behavior of aquatic non-target organisms. Accurate environmental risk assessment requires an understanding of whether antidepressants with similar modes of action have consistent negative impacts. Here, we tested the effect of acute exposure to two antidepressants, fluoxetine and venlafaxine (0-50 µg/L), on the behavior of non-target organism, i.e., freshwater pond snail, Lymnaea stagnalis. As compounds interact with chemical cues in the aquatic ecosystems, we also tested whether the effects altered in the presence of bile extract containing 5α-cyprinol sulfate (5α-CPS), a characterized kairomone of a natural predator, common carp (Cyprinus carpio). Behavior was studied using automated tracking and analysis of various locomotion parameters of L. stagnalis. Our results suggest that there are differences in the effects on locomotion upon exposure to venlafaxine and fluoxetine. We found strong evidence for a non-monotonic dose response on venlafaxine exposure, whereas fluoxetine only showed weak evidence of altered locomotion for a specific concentration. Combined exposure to compounds and 5α-CPS reduced the intensity of effects observed in the absence of 5α-CPS, possibly due to reduced bioavailability of the compounds. The results highlight the need for acknowledging different mechanisms of action among antidepressants while investigating their environmental risks. In addition, our results underline the importance of reporting non-significant effects and acknowledging individual variation in behavior for environmental risk assessment.

Evaluation of precopulatory pairing behaviour and male fertility in a marine amphipod exposed to plastic additives

Plastics contain a mixture of chemical additives that can leach into the environment and potentially cause harmful effects on reproduction and the endocrine system. Two of these chemicals, N-butyl benzenesulfonamide (NBBS) and triphenyl phosphate (TPHP), are among the top 30 organic chemicals detected in surface and groundwater and are currently placed on international watchlist for evaluation. Although bans have been placed on legacy pollutants such as diethylhexyl phthalate (DEHP) and dibutyl phthalate (DBP), their persistence remains a concern. This study aimed to examine the impact of plastic additives, including NBBS, TPHP, DBP, and DEHP, on the reproductive behaviour and male fertility of the marine amphipod Echinogammarus marinus. Twenty precopulatory pairs of E. marinus were exposed to varying concentrations of the four test chemicals to assess their pairing behaviour. A high-throughput methodology was developed and optimised to record the contact time and re-pair time within 15 min and additional point observations for 96 h. The study found that low levels of NBBS, TPHP, and DEHP prolonged the contact and re-pairing time of amphipods and the proportion of pairs reduced drastically with re-pairing success ranging from 75% to 100% in the control group and 0%-85% in the exposed groups at 96 h. Sperm count declined by 40% and 60% in the 50 μg/l and 500 μg/l DBP groups, respectively, whereas TPHP resulted in significantly lower sperms in 50 μg/l exposed group. Animals exposed to NBBS and DEHP showed high interindividual variability in all exposed groups. Overall, this study provides evidence that plastic additives can disrupt the reproductive mechanisms and sperm counts of amphipods at environmentally relevant concentrations. Our research also demonstrated the usefulness of the precopulatory pairing mechanism as a sensitive endpoint in ecotoxicity assessments to proactively mitigate population-level effects in the aquatic environment.

Developmental fluoxetine exposure affects adolescent and adult bone depending on the dose and period of exposure in mice

At the end of gestation, fetal skeleton rapidly accumulates calcium, and bone development continues in offspring postnatally. To accommodate, maternal skeletal physiology is modulated in a serotonin-dependent manner. Selective serotonin reuptake inhibitors (SSRIs) are generally considered safe for treatment of major depressive disorder, postpartum depression, and other psychiatric illnesses during the peripartum period, but because serotonin affects bone remodeling, SSRIs are associated with decreased bone mass across all ages and sexes, and the impact of SSRIs during fetal and postnatal development has not been fully investigated. In the present study, our aim was to examine developmental fluoxetine exposure on offspring skeleton and to assess varying degrees of impact depending on dose and window of exposure in short-term and long-term contexts. We established that a low dose of lactational fluoxetine exposure caused a greater degree of insult to offspring bone than either a low dose during fetal and postpartum development or a high dose during lactation only in mice. We further discovered lasting impacts of developmental fluoxetine exposure, especially during lactation only, on adult bone and body composition. Herein, we provide evidence fluoxetine exposure during early development may have detrimental effects on the skeleton of offspring at weaning and into adulthood.

The occurrence of typical psychotropic drugs in the aquatic environments and their potential toxicity to aquatic organisms - A review

Psychotropic drugs (PDs) and their bioactive metabolites often persist in aquatic environments due to their typical physical properties, which made them resistant to removal by traditional wastewater treatment plants (WWTPs). Consequently, such drugs and/or their metabolites are frequently detected in both aquatic environments and organisms. Even at low concentrations, these drugs can exhibit toxic effects on non-target organisms including bony fish (zebrafish (Danio rerio) and fathead minnows) and bivalves (freshwater mussels and clams). This narrative review focuses on the quintessential representatives of three different categories of PDs-antiepileptics, antidepressants, and antipsychotics. The data regarding their concentrations occurring in the environment, patterns of distribution, the degree of enrichment in various tissues of aquatic organisms, and the toxicological effects on them are summarized. The toxicological assessments of these drugs included the evaluation of their effects on the reproductive, embryonic development, oxidative stress-related, neurobehavioral, and genetic functions in various experimental models. However, the mechanisms underlying the toxicity of PDs to aquatic organisms and their potential health risks to humans remain unclear. Most studies have focused on the effects caused by acute short-term exposure due to limitations in the experimental conditions, thus making it necessary to investigate the chronic toxic effects at concentrations that are in coherence with those occurring in the environment. Additionally, this review aims to raise awareness and stimulate further research efforts by highlighting the gaps in the understanding of the mechanisms behind PD-induced toxicity and potential health risks. Ultimately, the study underscores the importance of developing advanced remediation methods for the removal of PDs in WWTPs and encourages a broader discussion on mitigating their environmental impacts.

Effects of the antidepressant fluoxetine on the swimming behaviour of the amphipod Gammarus pulex: Comparison of short-term and long-term toxicity in the laboratory and the semi-field

Fluoxetine is one of the worlds most prescribed antidepressant, and frequently detected in surface waters. Once present in the aquatic environment, fluoxetine has been shown to disrupt the swimming behaviour of fish and invertebrates. However, swimming behaviour is also known to be highly variable according to experimental conditions, potentially concealing relevant effects. Therefore, the aims of this study were two-fold: i) investigate the swimming and feeding behaviour of Gammarus pulex after exposure to the antidepressant fluoxetine (0.2, 2, 20, and 200 μg/L), and ii) assess to what degree the experimental test duration (short-term and long-term) and test location (laboratory and semi-field conditions) affect gammarid's swimming behaviour. We used automated video tracking and analysis to asses a range of swimming behaviours of G. pulex, including swimming speed, startle responses after light transition, acceleration, curvature and thigmotaxis. We found larger effects on the swimming behaviour of G. pulex due to experimental conditions than due to tested antidepressant concentrations. Gammarids swam faster, more straight and showed a stronger startle response during light transition when kept under semi-field conditions compared to the laboratory. Effects found for different test durations were opposite in the laboratory and semi-field. In the laboratory gammarids swam slower and spent more time at the inner zone of the arena after 2 days compared to 21 days while for the semi-field the reverse was observed. Fluoxetine had only minor impacts on the swimming behaviour of G. pulex, but experimental conditions influenced behavioural outcomes in response to fluoxetine exposure. Overall, our results highlight the importance of standardizing and optimizing experimental protocols that assess behaviour to achieve reproducible results in ecotoxicology.

Among-individual variation in the swimming behaviour of the amphipod Gammarus pulex under dark and light conditions

In recent years, considerable computational advancements have been made allowing automated analysis of behavioural endpoints using video cameras. However, the results of such analyses are often confounded by a large variation among individuals, making it problematic to derive endpoints that allow distinguishing treatment effects in behavioural studies. In this study, we quantitatively analysed the effects of light conditions on the swimming behaviour of the freshwater amphipod Gammarus pulex by high-throughput tracking, and attempted to unravel among individual variation using size and sex. For this, we developed the R-package Kinematics, allowing for the rapid and reproducible analysis of the swimming behaviour (speed, acceleration, thigmotaxis, curvature and startle response) of G. pulex, as well as any other organism. Our results show a considerable amount of variation among individuals (standard deviation ranging between 5 and 115 % of the average swimming behaviour). The factors size and sex and the interaction between the two only explained a minor part of this found variation. Additionally, our study is the first to quantify the startle response in G. pulex after the light is switched on, and study the variability of this response between individuals. To analyse this startle response, we established two metrics: 1) startle response magnitude (the drop in swimming velocity directly after the light switches on), and 2) startle response duration (the time it takes to recover from the drop in swimming velocity to average swimming speed). Almost 80 % of the individuals showed a clear startle response and, therefore, these metrics demonstrate a great potential for usage in behavioural studies. The findings of this study are important for the development of appropriate experimental set-ups for behavioural experiments with G. pulex.

Determination of the Effect of Wastewater on the Biological Activity of Mixtures of Fluoxetine and Its Metabolite Norfluoxetine with Nalidixic and Caffeic Acids with Use of E. coli Microbial Bioindicator Strains

In the present work, the conducted research concerned the determination of the toxicity and oxidative stress generation of the antidepressant fluoxetine (FLU), its metabolite nor-fluoxetine (Nor-FLU), the antibiotic nalidixic acid (NA), caffeic acid (CA) and their mixtures in three different environments: microbial medium (MM), raw wastewaters (RW) and treated wastewaters (TW). We evaluated the following parameters: E. coli cell viability, toxicity and protein damage, sodA promoter induction and ROS generation. It was found that FLU, Nor-FLU, NA, CA and their mixtures are toxic and they have the potency to generate oxidative stress in E. coli strains. We also detected that the wastewater, in comparison to the microbial medium, had an influence on the toxic activity and oxidative stress synthesis of the tested chemicals and their mixtures. Regardless of the environment under study, the strongest toxic activity and oxidative stress generation were detected after bacterial incubation with NA at a concentration of 1 mg/dm³ and the mixture of FLU (1 mg/dm³) with Nor-FLU (0.1 mg/dm³) and with NA (0.1 mg/dm³). The ROS synthesis and sodA promoter induction suggest that, in the case of the examined compounds and their mixtures, oxidative stress is the mechanism of toxicity. The analysis of the types of interactions among the substances constituting the mixtures in the wastewater revealed synergism, potentiation and antagonism.

Antidepressant pharmaceuticals in aquatic systems, individual-level ecotoxicological effects: growth, survival and behavior

The growing consumption of antidepressant pharmaceuticals has resulted in their widespread occurrence in the environment, particularly in waterways with a typical concentration range from ng L^-1 to μg L^-1. An increasing number of studies have confirmed the ecotoxic potency of antidepressants, not only at high concentrations but also at environmentally relevant levels. The present review covers literature from the last decade on the individual-level ecotoxicological effects of the most commonly used antidepressants, including their impact on behavior, growth, and survival. We focus on the relationship between antidepressants physico-chemical properties and dynamics in the environment. Furthermore, we discuss the advantages of considering behavioral changes as sensitive endpoints in ecotoxicology, as well as some current methodological shortcomings in the field, including low standardization, reproducibility and context-dependency.

Designing of ZnO nanoparticles oriented interface imprinted electrochemical sensor for fluoxetine detection

This study represents nanoparticle-based well-oriented recognition sites via interface imprinting, followed by selective and sensitive determination of fluoxetine (FLX). Herein, FLX was firstly immobilized onto ZnO NPs, and then polymerization was carried out with MAPA, HEMA, and EGDMA on the glassy carbon electrode via photopolymerization. After the etching of ZnO with and 10 mM HCI solution, a porous structure with recognition sites for FLX was constructed onto surface. The characterization of the electrochemical sensor was accomplished by utilizing CV, EIS, ATR-FTIR AFM, and SEM analysis. The DPV was used to determine FLX in standard solution, serum sample, and tap water. The effect of FLX concentration variation was studied using the DPV in the range of 1.0 × 10^-11 M to 1.0 × 10^-10 M with a detection limit of 2.67 × 10^-12 M. This sensor showed specific recognition toward template, and more than 90% of its original response was retained after being stored in the desiccator at R.T. for 5 days. This technique has proven to be a powerful, highly selective, and sensitive tool for the rapid detection of FLX in tap water and spike serum samples.

Contrasting dose response relationships of neuroactive antidepressants on the behavior of C. elegans

Antidepressant prescriptions are on a rise worldwide and this increases the concerns for the impacts of these pharmaceuticals on nontarget organisms. Antidepressants are neuroactive compounds that can affect organism's behavior. Behavior is a sensitive endpoint that may also propagate effects at a population level. Another interesting aspect of antidepressants is that they have shown to induce non-monotonic dose-response (NMDR) curves. While such NMDR relationships may have clear implications for the environmental risk, the resolution of current studies is often too coarse to be able to detect relevant NMDR. Therefore, the current study was performed into the behavioral effects (activity, feeding and chemotaxis) in Caenorhabditis elegans as the model organism of the selective serotonin reuptake inhibitors fluoxetine and sertraline and the acetylcholinesterase inhibiting pesticide chlorpyrifos, using a wide range of concentrations (ng/l to mg/l). In order to statistically examine the non-monotonicity, nonlinear regression models were applied to the results. The results showed a triphasic dose-response relationship for activity and chemotaxis after exposure to fluoxetine, but not to sertraline or chlorpyrifos. Effects of fluoxetine already occurred at low concentrations in the range of ng/l while sertraline only showed effects at concentrations in the μg/l range, similar to chlorpyrifos. The different responses between fluoxetine and sertraline, both SSRIs, indicate that response patterns may not always be extrapolated from chemicals with the same primary mode of action. The effects of fluoxetine at low concentrations, in a non-monotonic manner, confirm the relevance of examining such responses at low concentrations.

The role of serotonergic signaling on phototactic and locomotor behavior in Daphnia magna

The role of serotonin in Daphnia magna phototactic and locomotor behavior was assessed using reverse genetics and pharmacological treatments with serotonin and fluoxetine. The study was conducted with four clones: the wild type clone and three CRISPR D. magna ones with mutations in the tryptophan hydrolase gene (TRH) that is involved in serotonin synthesis. These included clones TRHA- and TRHB- with mutations in both alleles that lack serotonin and the mono-allelic mutant TRH+, that has serotonin. Obtained results indicated that animals lacking serotonin showed an increased negative phototactism and locomotor activity upon light stimuli and a reduced response to fish kairomones relative to the wild type and TRH+ individuals. Exposure to exogenous serotonin re-established the phototactism and locomotor activity of TRH- individuals to those of the wild type but did not affect phototactic responses to fish kairomones. Unexpectedly, fluoxetine was able to modify locomotor activity and phototactic behavior against fish kairomones in TRH- individuals lacking serotonin, and also it increased the concentrations of acethylcholine and GABA in exposed animals, which support the argument that fluoxetine may also affect other neurological pathways.

Transcriptome profiling reveals toxicity mechanisms following sertraline exposure in the brain of juvenile zebrafish (Danio rerio)

Sertraline (SER) is one of the most commonly detected antidepressants in the aquatic environment that can negatively affect aquatic organisms at low concentrations. Despite some knowledge on its acute toxicity to fish, the effects of chronic SER exposure remain poorly understood along with any underlying mechanisms of SER-induced toxicity. To address this knowledge gap, the effects of chronic exposure to three SER concentrations from low to high were investigated in zebrafish. Juvenile zebrafish were exposed to three concentrations of 1, 10, or 100 μg/L of SER for 28 d, after which indicators of oxidative stress and neurotoxicity in the brain were measured. Superoxide dismutase (SOD) activity was significantly enhanced by SER at 1 up to 100 μg/L, and catalase (CAT) activity was significantly induced by SER at 1 or 10 μg/L. The activity of acetylcholinesterase (AChE) was significantly induced by 10 and 100 μg/L of SER, and the serotonin (5-HT) level was significantly increased by all three concentrations of SER. To ascertain mechanisms of SER-induced toxicity, transcriptomics was conducted in the brain of zebrafish following 100 μg/L SER exposure. The molecular signaling pathways connected with circadian system and the immune system were significantly altered in the zebrafish brain. Based on transcriptomic data, the expression levels of six circadian clock genes were measured, and three genes were significantly altered in relative abundance in fish from all experimental treatments with SER, including cryptochrome circadian regulator 2 (cry2), period circadian clock 2 (per2), and period circadian clock 3 (per3). We hypothesize that the circadian system may be related to SER-induced neurotoxicity and oxidative stress in the central nervous system. This study reveals potential mechanisms and key events (i.e., oxidative stress and neurotoxicity) associated with SER-induced toxicity, and improves understanding of the molecular and biochemical pathways putatively perturbed by SER.

Worst-case ranking of organic chemicals detected in groundwaters and surface waters in England

The Environment Agency has been using Gas Chromatography-Mass Spectrometry (GC-MS) and Accurate-mass Quadrupole Time-of-Flight (Q-TOF) / Liquid Chromatography-Mass Spectrometry (LC-MS) target screen analysis to semi-quantitatively measure organic substances in groundwater and surface water since 2009 for GC-MS and 2014 for LC-MS. Here we use this data to generate a worst-case "risk" ranking of the detected substances. Three sets of hazard values relating to effects on aquatic organisms, namely Water Framework Directive EQSs, NORMAN Network PNECs (hereafter NORMAN PNEC) and chronic Species Sensitivity Distribution (SSD) HC50s from Posthuma et al., (2019) were used for the assessment. These hazard values were compared to the highest measured concentration for each chemical to generate a worst-case hazard quotient (HQ). Calculated HQs for each metric were ranked, averaged and multiplied by rank for detection frequency to generate an overall ordering based on HQ and occurrence. This worst-case approach was then used to generate ranking lists for GC-MS and LC-MS detected substances in groundwater and surface water. Pesticides in the top 30 overall ranked list included more legacy pesticides in groundwater and more current use actives in surface water. Specific uses were linked to some high rankings (e.g. rotenone for invasive species control). A number of industrial and plastics associated chemicals were ranked highly in the groundwater dataset, while more personal care products and pharmaceuticals were highly ranked in surface waters. Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) compounds were commonly highly ranked in both environmental compartments. The approach confirmed high rankings for some substance (e.g. selected pesticides) from previous prioritization exercises, but also identified novel substance for consideration (e.g. some PFAS compounds and pharmaceuticals). Overall our approach provided a simple approach using readily accessible data to identify substances for further and more detailed assessment.

Differential effects of fluoxetine on the phototactic behavior of 3 amphipod species (Crustacea; Amphipoda)

We document phototactic responses in different amphipod populations of Gammarus minus, Stygobromus tenuis, and Crangonyx shoemakeri, each collected at 2-3 sites within the Washington DC area. We then assessed how baseline phototaxis was altered following either short-term (3-week) or long-term (6-week) exposure to 0.05 µg/L or 0.5 µg/L fluoxetine. Our results classify all species as significantly photonegative, a response that depended solely on the presence, not quality, of light. Short-term fluoxetine exposure caused some animals to become photoneutral, regardless of concentration, while others remained photonegative. Long-term exposure to 0.5 µg/L fluoxetine caused photoneutral behaviors in all surviving populations; exposure to 0.05 µg/L had variable effects. These differential effects were due to a significant effect of population/sampling location on photobehavior. Overall, these results identify species-specific effects of chronic fluoxetine exposure and underscore how the response to light in 7 geographically distinct populations is uniquely tuned to requirements for survival.

Wastewater effluent affects behaviour and metabolomic endpoints in damselfly larvae

Wastewater treatment plant effluents have been identified as a major contributor to increasing anthropogenic pollution in aquatic environments worldwide. Yet, little is known about the potentially adverse effects of wastewater treatment plant effluent on aquatic invertebrates. In this study, we assessed effects of wastewater effluent on the behaviour and metabolic profiles of damselfly larvae (Coenagrion hastulatum), a common aquatic invertebrate species. Four key behavioural traits: activity, boldness, escape response, and foraging (traits all linked tightly to individual fitness) were studied in larvae before and after one week of exposure to a range of effluent dilutions (0, 50, 75, 100%). Effluent exposure reduced activity and foraging, but generated faster escape response. Metabolomic analyses via targeted and non-targeted mass spectrometry methods revealed that exposure caused significant changes to 14 individual compounds (4 amino acids, 3 carnitines, 3 lysolipids, 1 peptide, 2 sugar acids, 1 sugar). Taken together, these compound changes indicate an increase in protein metabolism and oxidative stress. Our findings illustrate that wastewater effluent can affect both behavioural and physiological traits of aquatic invertebrates, and as such might pose an even greater threat to aquatic ecosystems than previously assumed. More long-term studies are now needed evaluate if these changes are linked to adverse effects on fitness. The combination of behavioural and metabolomic assessments provide a promising tool for detecting effects of wastewater effluent, on multiple biological levels of organisation, in aquatic ecosystems.

Bioavailability of citalopram to Daphnia magna in the presence of suspended sediments with various properties

The influence of suspended sediment (SPS) properties on the biological effects of antidepressant citalopram (CIT) was investigated in our study. For CIT exposure alone, the feeding behavior, energy available, glutathione-S-transferase (GST) activity of D. magna were vitally induced at 10 μg/L. In the presence of SPS, significant dose-dependent reduction in the ingestion and filtration rates were observed with the increase of SPS concentration, while SPS organic content (f_oc) of 1% exhibited the most serious aggravation. The protein was the main contributor to detoxification and cellular protection under the stress of CIT and SPS. Obvious disturbance effects on the malonaldehyde content, catalase and GST activities were observed for SPS of 0.1 g/L, 60-90 μm and f_oc of 2%. Overall, the important role of SPS properties on the biological effects of CIT should be taken into consideration for the accurate risk assessment of pollutants.

Foodborne fluoxetine impacts the immune response in rainbow trout (Oncorhynchus mykkis)

The aim of this study was to reveal the effects of foodborne fluoxetine on morphological and condition profile, hematological profile, biochemical and oxidative stress indices on juvenile rainbow trout. The study was performed according to OECD Guideline No. 215. Fluoxetine was incorporated into Biomar 921 pellets at a dose of 0.047 mg/kg (environmental concentration), 0.577 mg/kg and 6.7 mg/kg. There was statistically significant change in hematological profile, including an increasing trend in neutrophil/lymphocyte ratio and a decreasing trend in the number of lymphocytes. Measurements of oxidative stress indicated decreased activity of the detoxifying enzyme glutathione-S-transferase in the liver and kidney. However, the measurement of GR, GPx, CAT, SOD activity, and TBARS showed no changes. Histopathological examination revealed damage to the proximal tubules of caudal kidney in exposed groups. This study confirms that fluoxetine has a significant effect on immune response.

The Biological Effects of Pharmaceuticals in the Marine Environment

Environmental pharmaceuticals represent a threat of emerging concern for marine ecosystems. Widely distributed and bioaccumulated, these contaminants could provoke adverse effects on aquatic organisms through modes of action like those reported for target species. In contrast to pharmacological uses, organisms in field conditions are exposed to complex mixtures of compounds with similar, different, or even opposing therapeutic effects. This review summarizes current knowledge of the main cellular pathways modulated by the most common classes of environmental pharmaceuticals occurring in marine ecosystems and accumulated by nontarget species-including nonsteroidal anti-inflammatory drugs, psychiatric drugs, cardiovascular and lipid regulator agents, steroidal hormones, and antibiotics-and describes an intricate network of possible interactions with both synergistic and antagonistic effects on the same cellular targets and metabolic pathways. This complexity reveals the intrinsic limits of the single-chemical approach to predict the long-term consequences and future impact of pharmaceuticals at organismal, population, and community levels.

Pharmaceuticals in two watersheds in Eastern China and their ecological risks

Pharmaceuticals are of increasing environmental concern due to their potential threat to aquatic ecosystems. Intensive human activities are a major factor influencing the level of pharmaceutical pollution in aquatic ecosystems. In this study, we investigated the occurrence, ecological risks of 31 pharmaceuticals and the possible influence of human activities on pharmaceutical distribution in two watersheds in the Yangtze River Delta, Eastern China. The target compounds were grouped into six categories: three non-steroidal anti-inflammatory drugs, ten antibiotics, six cardiovascular drugs, five hormones, six psychotropic drugs, and one antiparasitic. All target pharmaceuticals were detected in the surface water samples, with dexamethasone (100% of samples), tetracycline (100% of samples), and cefradine (100% of samples) being the dominant compounds (maximum concentrations of 686, 128, and 2280 ng/L, respectively). The total pharmaceutical concentrations were significantly higher in the urban watershed (711-2790 ng/L, mean = 1150 ng/L) than in the peri-urban watershed (467-1525 ng/L, mean = 863 ng/L) (p < 0.05). Distinct variation in the total pharmaceutical concentration also occurred between the dry season (507-2790 ng/L, mean = 1100 ng/L) and the wet season (467-1525 ng/L, mean = 943 ng/L). Ecological risk assessment showed that in the two watersheds, benzylpenicillin potassium, tetracycline hydrochloride, chlormadinone, ampicillin, cefotaxime acid, atorvastatin, sertraline hydrochloride, and oxazepam posed a medium potential risk (0.1 < risk quotient < 1), while norethisterone posed a high potential risk (risk quotient > 1). Redundancy analysis revealed that the concentrations of pharmaceuticals in various categories were positively correlated with land-use type (urban and agricultural land-use percentages), population density, and distance from town in both watersheds. Urban and agricultural activities were likely the main factors influencing the concentrations and composition of pharmaceuticals in these aquatic environments. Positive correlations were also found between total pharmaceutical concentrations and population density in both watersheds, suggesting a significant contribution of human disturbance to pharmaceutical pollution. The results provide useful information for pharmaceutical pollution control, ecological risk assessment, and sustainable water management at the watershed scale.

Environmentally relevant concentrations of sertraline disrupts behavior and the brain and liver transcriptome of juvenile yellow catfish (Tachysurus fulvidraco): Implications for the feeding and growth axis

Sertraline (SER) is one of the most prevalent antidepressants detected in aquatic environments, but its impact on fish behavior and growth remain poorly understood. As such, behavior and growth were assessed in yellow catfish (Tachysurus fulvidraco) following SER exposure. SER induced shoaling, reduced food consumption and growth, and increased cannibalism at environmentally relevant concentrations. To ascertain toxicity mechanisms, acetylcholinesterase (AChE) activity and transcripts related to growth and feeding were measured. AChE activity was increased in fish exposed to 10 and 100 μg/L SER. Transcript levels of neuropeptide Y, somatostatin, growth hormone, and insulin growth factor 1 were reduced in the brain following SER exposure. RNA-seq conducted in brain and liver revealed that gene networks associated with feeding and growth (i.e. leptin expression networks in the brain and insulin signaling pathways in the liver) were altered, proposed to be associated with the decreased food intake and growth. The brain also accumulated SER, which may relate to neurobehavioral responses. Lastly, the main metabolite of SER, norsertraline, was detected in the liver, and may also relate to toxicity. This study uncovers mechanisms and key events proposed to lead to impaired behavior and growth after exposure to some antidepressants.

Effects of environmental antidepressants on colour change and locomotor behaviour in juvenile shore crabs, Carcinus maenas

Juvenile crabs of Carcinus maenas thrive in coastal waters reputed to be the receptacle of continental pollution. Amongst the many pollutants encountered, antidepressants, such as fluoxetine (FLX) and venlafaxine (VEN), often detected at the ng•L^-1 range, are particularly worrying because of their action on the levels of monoamines, such as serotonin, noradrenaline and dopamine. In crustaceans, those monoamines are involved in colour change through their action on neuropeptide hormones. In addition, they are known to have a role in different behaviours, such as locomotion. Both colour change and locomotion are strategies used by juvenile crabs to hide and escape from predators. To investigate if the presence of antidepressants may alter behaviours of ecological importance, juvenile crabs were exposed to environmentally realistic concentrations of either 5 ng•L^-1 of FLX alone or in combination with VEN at 5 ng•L^-1. The ability to change colour depending on the environment and the locomotor activity of juvenile crabs were monitored weekly over 25 days. Animals exposed to antidepressants displayed a different pattern of colour change than the controls, especially those exposed to the combination of FLX and VEN at 5 ng•L^-1 each, and were less efficient to adapt to their environment, i.e., they were not as pale and not as dark as controls or crabs exposed to FLX at 5 ng•L^-1. Moreover, juvenile crabs exposed to the combination of antidepressants exhibited an enhanced locomotor activity throughout the exposure period with a higher velocity and distance moved as well as more time spend moving. The alteration of cryptic behaviours, such as colour change and locomotion by antidepressants persistently present in marine environment at low concentrations may have an impact on the survival of juvenile of C. maenas on the long term.

High-Throughput Screening of Psychotropic Compounds: Impacts on Swimming Behaviours in Artemia franciscana

Animal behaviour is becoming increasingly popular as an endpoint in ecotoxicology due to its increased sensitivity and speed compared to traditional endpoints. However, the widespread use of animal behaviours in environmental risk assessment is currently hindered by a lack of optimisation and standardisation of behavioural assays for model species. In this study, assays to assess swimming speed were developed for a model crustacean species, the brine shrimp Artemia franciscana. Preliminary works were performed to determine optimal arena size for this species, and weather lux used in the experiments had an impact on the animals phototactic response. Swimming speed was significantly lower in the smallest arena, whilst no difference was observed between the two larger arenas, suggesting that the small arena was limiting swimming ability. No significant difference was observed in attraction to light between high and low light intensities. Arena size had a significant impact on phototaxis behaviours. Large arenas resulted in animals spending more time in the light side of the arena compared to medium and small, irrespective of light intensity. The swimming speed assay was then used to expose specimens to a range of psychotropic compounds with varying modes of action. Results indicate that swimming speed provides a valid measure of the impacts of behaviour modulating compounds on A. franciscana. The psychotropic compounds tested varied in their impacts on animal behaviour. Fluoxetine resulted in increased swimming speed as has been found in other crustacean species, whilst oxazepam, venlafaxine and amitriptyline had no significant impacts on the behaviours measured. The results from this study suggest a simple, fast, high throughput assay for A. franciscana and gains insight on the impacts of a range of psychotropic compounds on the swimming behaviours of a model crustacean species used in ecotoxicology studies.

Sub-chronic effects of AgNPs and AuNPs on Gammarus fossarum (Crustacea Amphipoda): From molecular to behavioural responses

The aim of the present study was the assessment of the sub-chronic effects of silver (AgNPs) and gold nanoparticles (AuNPs) of 40 nm primary size either stabilised with citrate (CIT) or coated with polyethylene glycol (PEG) on the freshwater invertebrate Gammarus fossarum. Silver nitrate (AgNO₃) was used as a positive control in order to study the contribution of silver ions potentially released from AgNPs on the observed effects. A multibiomarker approach was used to assess the long-term effects of AgNPs and AuNPs 40 nm on molecular, cellular, physiological and behavioural responses of G. fossarum. Specimen of G. fossarum were exposed for 15 days to 0.5 and 5 µgL^-1 of CIT and PEG AgNPs and AuNPs 40 nm in the presence of food. A significant uptake of both Ag and Au was observed in exposed animals but was under the toxic threshold leading to mortality of G. fossarum. Silver nanoparticles (CIT-AgNPs and PEG-AgNPs 40 nm) led to an up-regulation of Na⁺K⁺ATPase gene expression. An up-regulation of Catalse and Chitinase gene expressions due to exposure to PEG-AgNPs 40 nm was also observed. Gold nanoparticles (CIT and PEG-AuNPs 40 nm) led to an increase of CuZnSOD gene expression. Furthermore, both AgNPs and AuNPs led to a more developed digestive lysosomal system indicating a general stress response in G. fossarum. Both AgNPs and AuNPs 40 nm significantly affected locomotor activity of G. fossarum while no effects were observed on haemolymphatic ions and ventilation.

Multicompartment and cross-species monitoring of contaminants of emerging concern in an estuarine habitat

The fate of many chemicals in the environment, particularly contaminants of emerging concern (CEC), have been characterised to a limited extent with a major focus on occurrence in water. This study presents the characterisation, distribution and fate of multiple chemicals including pharmaceuticals, recreational drugs and pesticides in surface water, sediment and fauna representing different food web endpoints in a typical UK estuary (River Colne, Essex, UK). A comparison of contaminant occurrence across different benthic macroinvertebrates was made at three sites and included two amphipods (Gammarus pulex &Crangon crangon), a polychaete worm (Hediste diversicolor) and a gastropod (Peringia ulvae). Overall, multiple contaminants were determined in all compartments and ranged from; Collapse

Key Words

• Environmental risk
• Invertebrate
• Occurrence
• Pesticides
• Pharmaceuticals
• Sediment

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MESH Headings

• Animals
• Ecosystem
• Environmental Monitoring
• Pesticides/analysis
• Rivers
• Water Pollutants, Chemical/analysis

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Grants

• MR/S019669/1 Medical Research Council

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Affiliation(s)

Thomas H Miller Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Kingston Lane, UB8 3PH, UK; Department of Analytical, Environmental & Forensic Sciences, School of Population Health & Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, 150 Stamford Street, London, SE1 9NH, UK.
Keng Tiong Ng Department of Analytical, Environmental & Forensic Sciences, School of Population Health & Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, 150 Stamford Street, London, SE1 9NH, UK; Environmental Research Group, School of Public Health, Faculty of Medicine, Imperial College London, UK
Aaron Lamphiere School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO43SQ, UK
Tom C Cameron School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO43SQ, UK
Nicolas R Bury School of Science, Technology and Engineering, University of Suffolk, James Hehir Building, University Avenue, Ipswich, Suffolk, IP3 0FS, UK; Suffolk Sustainability, University of Suffolk, Waterfront Building, Neptune Quay, Ipswich, IP4 1QJUK, UK
Leon P Barron Department of Analytical, Environmental & Forensic Sciences, School of Population Health & Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, 150 Stamford Street, London, SE1 9NH, UK; Environmental Research Group, School of Public Health, Faculty of Medicine, Imperial College London, UK

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A combination of six psychoactive pharmaceuticals at environmental concentrations alter the locomotory behavior of clonal marbled crayfish

Pharmaceutically active compounds (PhACs) are ubiquitous in the aquatic environment worldwide and considered emerging contaminants. Their effects on growth, behavior, and physiological processes of aquatic organisms have been identified even at very low concentrations. Ecotoxicological investigations have primarily focused on single compound exposure, generally at a range of concentrations. In the natural environment, pollutants seldom occur in isolation, but little is known about the effects and risks of combinations of chemicals. This study aimed to investigate the effects of concurrent exposure to six psychoactive PhACs on locomotory behavior and life history traits of clonal marbled crayfish Procambarus virginalis. Crayfish were exposed to ~1 μg L^-1 of the antidepressants sertraline, citalopram, and venlafaxine; the anxiolytic oxazepam; the opioid tramadol; and the widely abused psychostimulant methamphetamine. In the absence of shelter, exposed crayfish moved significantly shorter distances and at lower velocity and showed significantly less activity than controls. With available shelter, exposed crayfish moved significantly more distance, showed higher activity, and spent a significantly more time outside the shelter than controls. Molting, mortality, and spawning frequency did not vary significantly between the groups. Hemolymph glucose level did not vary among groups and was not correlated with observed behaviors. Results suggest that environmental concentrations of the tested compounds in combination can alter the behavior of non-target aquatic organisms as individual exposure of these compounds, which may lead to disruption of ecosystem processes due to their reduced caution in polluted conditions. Further research is needed using varied chemical mixtures, exposure systems, and habitats, considering molecular and physiological processes connected to behavior alterations.

The effects of wastewater effluent on multiple behaviours in the amphipod, Gammarus pulex

The prevalence of pharmaceuticals and personal care products (PPCPs) in lotic habitats is increasing, with the main source of these contaminants being effluent from waste water treatment works (WwTW). There is still much uncertainty about the impacts of these PPCPs at environmentally relevant concentrations and their potential effects on aquatic ecology. Behaviour is a sensitive endpoint which can help evaluate possible population level effects from changes in physiology. This paper evaluates the effects of WwTW effluent on a range of behaviours in the freshwater invertebrate, Gammarus pulex. Effluent taken from the outflow of two WwTW in southern England was used in the study. Behavioural analyses, namely feeding rate, phototaxis, activity, velocity and precopula pairing, were measured in G. pulex following a period of one and three weeks after exposure to a 50% or 100% effluent and a control. Mortality remained very low throughout the 3 week experiment (0-10%, n = 20) and no significant changes in moulting frequency were observed (p > 0.05). No significant effects on feeding or velocity or phototaxis following 3 weeks of effluent exposures were observed (p > 0.05). However, significant reductions were observed in the overall activity over 3 weeks across which appeared to be exacerbated by exposure to effluents. Interestingly, males exposed for 3 weeks to WwTW effluent re-paired with unexposed females significantly faster (4-6x) than control animals. This result was consistent between the effluents taken from the two WwTW. The implications of these behavioural changes are currently unknown but highlight the need for a varied set of tools to study the behavioural changes in wildlife.

Effects of the antidepressant fluoxetine on pigment dispersion in chromatophores of the common sand shrimp, Crangon crangon: repeated experiments paint an inconclusive picture

The effects of antidepressants in the environment are starting to generate considerable interest due to the fact that neurotransmitters influence a range of biological processes. Crypsis is an important behavioural and physiological response in many crustaceans modulated by monoamine and pigment dispersing/concentrating hormones. This study aimed to develop a test methodology and investigate the effects of the selective serotonin reuptake inhibitor (SSRI), fluoxetine, on a chromatophore index and overall carapace 'darkness' in the common sand shrimp Crangon crangon. Adult shrimp were exposed for either 1 h, 1 day or 1 week across a range of nominal fluoxetine concentrations (10 ng/L, 100 ng/L and 1000 ng/L) and the chromatophore index or carapace percentage 'darkness' was recorded following 30 min on white and black substrates. These experiments were repeated three times using different specimens. Animals became significantly darker (~20%) on darker background and lighter on light backgrounds as one might expect. However, time periods over which the animals were recorded had a significant impact on the colouration suggesting habituation to laboratory conditions. Fluoxetine exposure came up as a significant factor in two of the three trials for the chromatophore index but the results was inconsistent between trials. There was a high degree of correlation between the chromatophore index and the percentage darkness analyses however, there was no significant effects for fluoxetine exposure with the percentage darkness data. We conclude that the effects on antidepressants on colour change remain inconclusive from these experiments and we discuss potential areas to improve the repeatability of the experiments.

Chronic exposure to a pervasive pharmaceutical pollutant erodes among-individual phenotypic variation in a fish

Pharmaceutical pollution is now recognised as a major emerging agent of global change. Increasingly, pharmaceutical pollutants are documented to disrupt ecologically important physiological and behavioural traits in exposed wildlife. However, little is known about potential impacts of pharmaceutical exposure on among-individual variation in these traits, despite phenotypic diversity being critical for population resilience to environmental change. Furthermore, although wildlife commonly experience multiple stressors contemporaneously, potential interactive effects between pharmaceuticals and biological stressors-such as predation threat-remain poorly understood. To redress this, we investigated the impacts of long-term exposure to the pervasive pharmaceutical pollutant fluoxetine (Prozac®) on among-individual variation in metabolic and behavioural traits, and the combined impacts of fluoxetine exposure and predation threat on mean metabolic and behavioural traits in a freshwater fish, the guppy (Poecilia reticulata). Using a mesocosm system, guppy populations were exposed for 15 months to one of two field-realistic levels of fluoxetine (nominal concentrations: 30 and 300 ng/L) or a solvent control. Fish from these populations were then tested for metabolic rate (oxygen uptake) and behaviour (activity), both before and after experiencing one of three levels of a predation treatment: an empty tank, a non-predatory fish (Melanotaenia splendida) or a predatory fish (Leiopotherapon unicolor). Guppies from both fluoxetine treatments had ∼70% lower among-individual variation in their activity levels, compared to unexposed fish. Similarly, fluoxetine exposure at the higher dosage was associated with a significant (26%) reduction in individual-level variation in oxygen uptake relative to unexposed fish. In addition, mean baseline metabolic rate was disrupted in low-fluoxetine exposed fish, although mean metabolic and behavioural responses to predation threat were not affected. Overall, our study demonstrates that long-term exposure to a pervasive pharmaceutical pollutant alters ecologically relevant traits in fish and erodes among-individual variability, which may be detrimental to the stability of contaminated populations globally.

Application of Biomarker Tools Using Bivalve Models Toward the Development of Adverse Outcome Pathways for Contaminants of Emerging Concern

As contaminant exposures in aquatic ecosystems continue to increase, the need for streamlining research efforts in environmental toxicology using predictive frameworks also grows. One such framework is the adverse outcome pathway (AOP). An AOP framework organizes and utilizes toxicological information to connect measurable molecular endpoints to an adverse outcome of regulatory relevance via a series of events at different levels of biological organization. Molecular endpoints or biomarkers are essential to develop AOPs and are valuable early warning signs of the toxicity of pollutants, including contaminants of emerging concern. Ecological risk-assessment approaches using tools such as biomarkers and AOPs benefit from identification of molecular targets conserved across species. Bivalve models are useful in such approaches and integral to our understanding of ecological and human health risks associated with contaminant exposures. We discuss the value of using biomarker approaches in bivalve models to meet the demands of twenty-first-century toxicology. Environ Toxicol Chem 2020;39:1472-1484. © 2020 SETAC.

Long-Term Pharmaceutical Contamination and Temperature Stress Disrupt Fish Behavior

Natural environments are subject to a range of anthropogenic stressors, with pharmaceutical pollution being among the fastest-growing agents of global change. However, despite wild animals living in complex multi-stressor environments, interactions between pharmaceutical exposure and other stressors remain poorly understood. Accordingly, we investigated effects of long-term exposure to the pervasive pharmaceutical contaminant fluoxetine (Prozac) and acute temperature stress on reproductive behaviors and activity levels in the guppy (Poecilia reticulata). Fish were exposed to environmentally realistic fluoxetine concentrations (measured average: 38 or 312 ng/L) or a solvent control for 15 months using a mesocosm system. Additionally, fish were subjected to one of three acute (24 h) temperature treatments: cold stress (18 °C), heat stress (32 °C), or a control (24 °C). We found no evidence for interactive effects of fluoxetine exposure and temperature stress on guppy behavior. However, both stressors had independent impacts. Fluoxetine exposure resulted in increased male coercive copulatory behavior, while fish activity levels were unaffected. Under cold-temperature stress, both sexes were less active and males exhibited less frequent reproductive behaviors. Our results demonstrate that long-term exposure to a common pharmaceutical pollutant and acute temperature stress alter fundamental fitness-related behaviors in fish, potentially shifting population dynamics in contaminated ecosystems.

First record of emerging contaminants in sponges of an inhabited island in the Maldives

In the Maldivian islands, the lack of sewage wastewater treatment and an improper landfill enhance the potential hazard of emerging contaminants, including pharmaceuticals and personal care products. In order to analyze the occurrence of emerging contaminants in the marine biota, sponges were collected in two coral reef areas of Magoodhoo island (Faafu), one near the landfill and the other furthest from the island. Caffeine, fluoxetine and norfluoxetine were detected only in the proximity of the landfill, with caffeine showing the highest concentration (28.4 ng/g d.w.), followed by fluoxetine (6.00 ng/g d.w.). Norfluoxetine was below the limit of quantification of 10 ng/g d.w. Nitro xylene, N,N-Diethyl-meta-toluamide and galaxolide were found in both areas, with concentrations of 3.51/6.11/8.54 and <LOQ/1.14/0.62 ng/g d.w., respectively. Due to the vital role of the coral reef for the livelihood and economy of the Maldivian people, attention should be paid to this class of contaminant.

Selected Pharmaceuticals in Different Aquatic Compartments: Part II-Toxicity and Environmental Risk Assessment

Potential risks associated with releases of human pharmaceuticals into the environment have become an increasingly important issue in environmental health. This concern has been driven by the widespread detection of pharmaceuticals in all aquatic compartments. Therefore, 22 pharmaceuticals, 6 metabolites and transformation products, belonging to 7 therapeutic groups, were selected to perform a review on their toxicity and environmental risk assessment (ERA) in different aquatic compartments, important issues to tackle the water framework directive (WFD). The toxicity data collected reported, with the exception of anxiolytics, at least one toxicity value for concentrations below 1 µg L⁻¹. The results obtained for the ERA revealed risk quotients (RQs) higher than 1 in all the aquatic bodies and for the three trophic levels, algae, invertebrates and fish, posing ecotoxicological pressure in all of these compartments. The therapeutic groups with higher RQs were hormones, antiepileptics, anti-inflammatories and antibiotics. Unsurprisingly, RQs values were highest in wastewaters, however, less contaminated water bodies such as groundwaters still presented maximum values up to 91,150 regarding 17α-ethinylestradiol in fish. Overall, these results present an important input for setting prioritizing measures and sustainable strategies, minimizing their impact in the aquatic environment.

Complete transcriptome assembly and annotation of a critically important amphipod species in freshwater ecotoxicological risk assessment: Gammarus fossarum

Because of their crucial role in ecotoxicological risk assessment, amphipods (Crustacea) are commonly employed as model species in a wide range of studies. However, despite their ecological importance, their genome has not yet been completely annotated and molecular mechanisms underlying key pathways, such as the serotonin pathway, in development of ecotoxicological biomarkers of exposure to neuroactive pharmaceuticals are still poorly understood. Furthermore, genetic similarities and discrepancies with other model arthropods (e.g., Drosophila melanogaster) have not been completely clarified. In this report, we present a new transcriptome assembly of Gammarus fossarum, an important amphipod species, widespread in Central Europe. RNA-Seq with Illumina HiSeq technology was used to analyse samples extracted from total internal tissues. We used the Trinity and Trinotate software suites for transcriptome assembly and annotation, respectively. The quality of this assembly and the affiliated targeted homology searches greatly enrich the molecular knowledge on this species. Because of the lack of publicly available molecular information on the serotonin pathway, we also highlighted sequence homologies and divergences of the genes encoding the serotonin pathway components of the well-annotated arthropod D. melanogaster, and Crustacea with the corresponding genes of our assembly. An inferior number of hits was found when running a BLAST analysis of both D. melanogaster and Crustacea mRNA sequences encoding serotonin receptors available in GenBank against the total assembly, compared to other serotonin pathway components. A lack of information on important components for serotonin biosynthesis and vesicle endocytosis (i.e., tryptophan hydroxylase and vesicular monoamine transporter) in Crustacea was also brought to light. Our results will provide an extensive transcriptional resource for this important species in ecotoxicological risk assessment and highlight the need for a more detailed categorization of neuronal pathways components in invertebrates.

The effect of foodborne sertraline on rainbow trout (Oncorhynchus mykiss)

The worldwide consumption of antidepressants is raising as well as their concentrations in the aquatic environment. This increases the risk of food chain contamination and bioaccumulation in aquatic biota. The aim of this study was to describe a potential risk of sertraline as a pollutant from water environment, wherein rainbow trout (Oncorhynchus mykiss) has been chosen as the test organism, because predatory fish are on the top of the food chain in the aquatic environment. The effects of foodborne sertraline were tested on rainbow trout during a 28-day toxicity test according to OECD 215 method. Sertraline was incorporated in commercial feed at a dose of 4.4 µg/kg (environmental concentration), 42 µg/kg and 400 µg/kg. The results confirmed that sertraline has a significant effect on fish behaviour, resulting in suppression of the escape reflex and increased resistance to stress. Moreover, increased Fultońs condition factor was found in fish fed with the highest concentration of sertraline. Haematological analysis revealed a statistically significant increase in the number of neutrophilic bands and neutrophil/lymphocyte ratio, and decreased number of lymphocytes. The results of biochemical examination showed a statistically significant decrease in ammonia and lactate concentrations and histological examination revealed changes in gills and caudal kidney. Although sertraline reduces stress in fish, the decline in nonspecific immunity is a risk to fish population stability.

Two antidepressants fluoxetine and sertraline cause growth retardation and oxidative stress in the marine rotifer Brachionus koreanus

To understand effects of two widely used antidepressant on the antioxidant defense mechanism in the marine rotifer Brachionus koreanus, we assessed acute toxicity and measured population growth, reactive oxygen species (ROS) levels, glutathione (GSH) levels, and antioxidant enzymatic activities (GST, GR, and SOD) in response to fluoxetine hydrochloride (FLX) and sertraline hydrochloride (SER). The no observed effect concentration-24 h of fluoxetine and sertraline were 1000 μg/L and 450 μg/L, respectively, whereas the median lethal concentration (LC50)-24 h of fluoxetine and sertraline were 1560 μg/L and 507 μg/L, respectively. Both fluoxetine and sertraline caused significant reduction (P < 0.05) in the population growth rate indicating that both antidepressants have a potential adverse effect on life cycle parameters of B. koreanus. The intracellular ROS level and GSH level were significantly modulated (P < 0.05) in response to fluoxetine and sertraline. In addition, antioxidant enzymatic activities have shown significant modulation (P < 0.05) in response to FLX and SER in B. koreanus. Furthermore, transcriptional profiles of antioxidant genes (GSTs, SODs, and GR) have shown modulation in response to FLX compared to SER-exposed B. koreanus. Our results indicate that fluoxetine and sertraline induce oxidative stress, leading to reduction in the population density and modulation of antioxidant defense mechanism in the marine rotifer B. koreanus.

Impacts of ionising radiation on sperm quality, DNA integrity and post-fertilisation development in marine and freshwater crustaceans

Crustaceans have been designated as internationally important model organisms in the development of environmental radioprotection measures. Despite the known sensitivity of sperm to ionizing radiation, the impacts of chronic radiation exposure on male fertility in crustaceans have not been studied. For the first time, the present study aimed to assess the impacts of chronic radiation exposure on male fertility, sperm DNA damage and concomitant impacts on breeding in two amphipod crustaceans. Echinogammarus marinus and Gammarus pulex (male fertility only) were exposed to phosphorus-32 at dose rates of 0, 0.1, 1 and 10 mGy/d and sperm parameters, DNA damage and knock-on impacts on breeding were assessed. Sperm quality parameters and DNA damage were assessed using a fluorescent staining method and single cell gel electrophoresis respectively. Concomitant effects of male exposure to radiation on fecundity were determined by pairing phosphorus-32 exposed males to unexposed sexually mature females. In E. marinus, a statistically significant reduction of 9 and 11% in the quality of sperm was recorded at dose rates of 1 and 10 mGy/d respectively, with no significant effects recorded on sperm counts. Conversely in the freshwater G. pulex, no significant impact of radiation on sperm quantity or quality was recorded. For E. marinus, a statistically significant increase in DNA damage was recorded at doses of 10 mGy/d. Reduced fecundity and an increase in the frequency of abnormal embryos was recorded in female E. marinus breeding with males exposed to radiation. These findings suggest sperm quality may be a sensitive indicator of radiation exposure in invertebrates with potential impacts on the unexposed embryo, though unclear dose-response and differences between two closely related species necessitate further study before robust conclusions can be drawn.

Does the antidepressant sertraline show chronic effects on aquatic invertebrates at environmentally relevant concentrations? A case study with the keystone amphipod, Gammarus locusta

The increasing use of Sertraline (SER) as antidepressant and its consequent presence in the aquatic environment is raising concern about the chronic effects of this pharmaceutical to aquatic organisms. As the current concentrations of SER in surface waters are typically in the low ng/L range, acute toxicity is unlikely to occur. However, prolonged exposure to low concentrations of SER may lead to sub-lethal effects in aquatic organisms, including alterations in important physiological functions like growth, reproduction, behaviour, and also in key biochemical processes, such as those associated with neurotransmission and redox balance. To test this hypothesis, we selected the amphipod Gammarus locusta, a keystone species used in ecotoxicological hazard assessment. In the present study, juveniles' G. locusta from a permanent laboratory culture were chronically exposed to low concentrations of SER (8-1000 ng/L) in a bioassay that lasted for 48 days, allowing for a life-cycle study including effects on reproduction. At the lowest SER concentrations with environmental relevance (8, 40 and 200 ng/L) we detected no significant changes in key ecological endpoints such as survival, growth, reproduction and movement behaviour, or in any of the biochemical markers analysed. However, at 1000 ng/L SER (a concentration one order of magnitude higher than the levels reported in aquatic environments) females showed a significant increase in movement versus control, whereas no activity changes were observed in males. Overall, these findings indicate that G. locusta females are potentially more susceptible to the chronic effects of SER. Moreover, the current environmental SER concentrations are unlikely to affect amphipod's ecological endpoints because only SER concentrations higher than the levels reported in aquatic environments produced effects on the behaviour of G. locusta females. However, the increasing consumption of SER, highlights the importance of monitoring its chronic risk to the aquatic wildlife.

Effects of antidepressants with different modes of action on early life stages of fish and amphibians

Drugs are excreted from the human body as both original substances and as metabolites and enter aquatic environment through waste water. The aim of this study was to widen the current knowledge considering the effects of waterborne antidepressants with different modes of action-amitriptyline, venlafaxine, sertraline-on embryos of non-target aquatic biota-fish (represented by Danio rerio) and amphibians (represented by Xenopus tropicalis). The tested concentrations were 0.3; 3; 30; 300 and 3000 μg/L in case of amitriptyline and venlafaxine and 0.1; 1; 10; 100 and 1000 μg/L for sertraline. Test on zebrafish embryos was carried out until 144 h post fertilization, while test on Xenopus embryos was terminated after 48 h. Lethal and sublethal effects as well as swimming alterations were observed at higher tested concentrations that are not present in the environment. In contrast, mRNA expression of genes related to heart, eye, brain and bone development (nkx2.5, otx 2, bmp4 and pax 6) seems to be impacted also at environmentally relevant concentrations. In a wider context, this study reveals several indications on the ability of antidepressants to affect non target animals occupying environments which may be contaminated by such compounds.

Behavioural effects on marine amphipods exposed to silver ions and silver nanoparticles

Behavioural responses to contaminants are an important endpoint in ecotoxicology because they link effects at biochemical or cellular levels to impacts on individual fitness. Due to the increasing use of silver in nanomaterials, studies of its effects on the behaviour of aquatic organisms are important to assess the risks of silver nanoparticles (AgNP) released into the environment. The aim of this work was to evaluate the behavioural effects of silver on the marine amphipod Echinogammarus marinus after exposure to AgNO₃ via water and AgCl or AgNP via food. Swimming activity of the amphipods was tracked during 6 min alternating dark and light conditions. Animals swam slower and responded less to light at higher concentrations of silver in the water. No differences were found in the behaviour of animals exposed via feeding up to 28 days, hence, longer exposure times may be required for the observation of effects. This is the first work to appraise behaviour effects of silver ions and AgNP on marine amphipods. Although the protocol has been successfully developed for this purpose, specimens appeared to habituate to test conditions during the experiments. Therefore, the need for further understanding of baseline behaviours in these model organisms is discussed.

Biomonitoring of pesticides, pharmaceuticals and illicit drugs in a freshwater invertebrate to estimate toxic or effect pressure

Multiple classes of environmental contaminants have been found in aquatic environments, globally. Understanding internalised concentrations in the organism could further improve the risk assessment process. The present study is concerned with the determination of several contaminant classes (107 compounds) in Gammarus pulex collected from 15 sites covering 5 river catchments across Suffolk, UK. Quantitative method performance was acceptable for 67 compounds including pharmaceuticals, pesticides, illicit drugs and drugs of abuse. A total of 56 compounds were detectable and ranged from Collapse

Key Words

• Environmental risk assessment
• Exposome
• Pesticides
• Pharmaceuticals

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MESH Headings

• Animals
• Environmental Monitoring/methods
• Fresh Water
• Humans
• Illicit Drugs/chemistry
• Illicit Drugs/toxicity
• Invertebrates/chemistry
• Pesticides/chemistry
• Pesticides/toxicity
• Toxicity Tests
• Water Pollutants, Chemical/chemistry

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Grants

• MR/S019669/1 Medical Research Council

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Affiliation(s)

Thomas H Miller Department of Analytical, Environmental & Forensic Sciences, School of Population Health & Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, 150 Stamford Street, London SE1 9NH, UK.
Keng Tiong Ng Department of Analytical, Environmental & Forensic Sciences, School of Population Health & Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, 150 Stamford Street, London SE1 9NH, UK
Samuel T Bury St Olaves Grammer School, Goddington Lane, Orpington, BR6 9SH, UK
Sophie E Bury Department of Pyschology, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
Nicolas R Bury School of Science, Technology and Engineering, University of Suffolk, James Hehir Building, University Avenue, Ipswich, Suffolk IP3 0FS, UK; Suffolk Sustainability Institute, University of Suffolk, Waterfront Building, Neptune Quay, Ipswich IP4 1QJ, UK
Leon P Barron Department of Analytical, Environmental & Forensic Sciences, School of Population Health & Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, 150 Stamford Street, London SE1 9NH, UK

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Environmentally relevant concentrations of methamphetamine and sertraline modify the behavior and life history traits of an aquatic invertebrate

Pharmaceutically active compounds are major contaminants of aquatic environments that show direct and indirect effects on aquatic organisms even at low concentrations. The aim of this study was to assess the effects of the illicit drug methamphetamine and the antidepressant sertraline on clonal marbled crayfish Procambarus virginalis. Crayfish exposed to the environmentally relevant concentrations of methamphetamine of ∼1 μg L^-1 did not exhibit significant differences from unexposed controls in distance moved, velocity, and activity level with or without available shelter. Sertraline-exposed (∼1 μg L^-1) crayfish were significantly more active, regardless of available shelter, and moved greater distances when shelter was available, compared to control crayfish. Crayfish exposed to methamphetamine and sertraline spent significantly more time outside the shelters compared to controls. Sertraline-exposed crayfish spawned more frequently and showed higher mortality than controls. The results suggest that the low environmental concentrations of the tested compounds could alter the behavior and life history traits of crayfish, resulting in higher reproductive effort and mortality.