The biological effects of antidepressants on the molluscs and crustaceans: a review

Contrasting alterations in brain chemistry in a crustacean intermediate host of two acanthocephalan parasites

The dynamic properties of neural systems throughout life can be hijacked by so-called manipulative parasites. This study investigated changes in the brain chemistry of the amphipod Gammarus fossarum in response to infection with two trophically-transmitted helminth parasites known to induce distinct behavioral alterations: the bird acanthocephalan Polymorphus minutus and the fish acanthocephalan Pomphorhynchus tereticollis. We quantified brain antioxidant capacity as a common marker of homeostasis and neuroprotection, and brain total protein, on 72 pools of six brains. We analyzed the concentration of serotonin (5HT), dopamine (DA) and tyramine in 52 pools of six brains, by using ultrafast high performance liquid chromatography with electrochemical detection (UHPLC-ECD). Brain total protein concentration scaled hypo-allometrically to dry body weight, and was increased in infected gammarids compared to uninfected ones. The brain of gammarids infected with P. minutus had significantly lower total antioxidant capacity relative to total proteins. Infection with P. tereticollis impacted DA level compared to uninfected ones, and in opposite direction between spring and summer. Brain 5HT level was higher in summer compared to spring independently of infection status, and was decreased by infection after correcting for brain total protein concentration estimated from dry whole-body weight. The potential implication of 5HT/DA balance in parasite manipulation, as a major modulator of the reward-punishment axis, is discussed. Taken together, these findings highlight the need to consider both brain homeostatic and/or structural changes (antioxidant and total protein content) together with neurotransmission balance and flexibility, in studies investigating the impact of parasites on brain and behavior.

Neuroendocrine functions of monoamines in invertebrates: Focus on bivalve molluscs

Monoamines (MA) such as serotonin, catecholamines (dopamine, norepinephrine, epinephrine), and trace amines (octopamine, tyramine), are neurotransmitters and neuroendocrine modulators in vertebrates, that contribute to adaptation to the environment. Although MA are conserved in evolution, information is still fragmentary in invertebrates, given the diversity of phyla and species. However, MA are crucial in homeostatic processes in these organisms, where the absence of canonical endocrine glands in many groups implies that the modulation of physiological functions is essentially neuroendocrine. In this review, we summarize available information on MA systems in invertebrates, with focus on bivalve molluscs, that are widespread in different aquatic environments, where they are subjected to a variety of environmental stimuli. Available data are reviewed on the presence of the different MA in bivalve tissues, their metabolism, target cells, signaling pathways, and the physiological functions modulated in larval and adult stages. Research gaps and perspectives are highlighted, in order to enrich the framework of knowledge on MA neuroendocrine functions, and on their role in adaptation to ongoing and future environmental changes.

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.

Evaluation of the citalopram toxicity on early development of zebrafish: Morphological, physiological and biochemical responses

Citalopram, an antidepressant drug have been detected in different environmental matrices due to its high consumption. Previous study has proved that citalopram may alter the behaviour of aquatic organisms at environmentally relevant concentrations. However, scientific knowledge is still lacking on the ecotoxicological effects of citalopram on aquatic organisms. For this reason, the present study is aimed to investigate the potential toxicity of citalopram in terms of development, antioxidant, neurotoxicity, apoptosis, lipogenesis, and bone mineralization in embryonic and larval zebrafish (Danio rerio) at environmentally relevant concentrations. We noticed that citalopram exposure at 1 and 10 μg/L concentration delays hatching and heartbeat at 24, 48, 72 and 96 hpf. Exposure to citalopram also significantly increased mortality at 10 μg/L. Abnormal development with yolk sac edema, pericardial edema and scoliosis were also observed after citalopram treatment. In addition, citalopram significantly (P < 0.001) induced superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST) and lipid peroxidation (LPO) levels. A significant decrease in acetylcholine esterase (AChE) activity was also observed in citalopram exposed groups. We found significant dose-and time-dependent increases in apoptosis, lipogenesis, and bone mineralization. In conclusion, the findings of the present study can provide new insights on the ecotoxicity of citalopram in the aquatic environment.

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.

Cross-Species Extrapolation of Biological Data to Guide the Environmental Safety Assessment of Pharmaceuticals-The State of the Art and Future Priorities

The extrapolation of biological data across species is a key aspect of biomedical research and drug development. In this context, comparative biology considerations are applied with the goal of understanding human disease and guiding the development of effective and safe medicines. However, the widespread occurrence of pharmaceuticals in the environment and the need to assess the risk posed to wildlife have prompted a renewed interest in the extrapolation of pharmacological and toxicological data across the entire tree of life. To address this challenge, a biological "read-across" approach, based on the use of mammalian data to inform toxicity predictions in wildlife species, has been proposed as an effective way to streamline the environmental safety assessment of pharmaceuticals. Yet, how effective has this approach been, and are we any closer to being able to accurately predict environmental risk based on known human risk? We discuss the main theoretical and experimental advancements achieved in the last 10 years of research in this field. We propose that a better understanding of the functional conservation of drug targets across species and of the quantitative relationship between target modulation and adverse effects should be considered as future research priorities. This pharmacodynamic focus should be complemented with the application of higher-throughput experimental and computational approaches to accelerate the prediction of internal exposure dynamics. The translation of comparative (eco)toxicology research into real-world applications, however, relies on the (limited) availability of experts with the skill set needed to navigate the complexity of the problem; hence, we also call for synergistic multistakeholder efforts to support and strengthen comparative toxicology research and education at a global level. Environ Toxicol Chem 2024;43:513-525. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Effects of parental exposure to amitriptyline on the survival, development, behavior, and gene expression in zebrafish offspring

In mammals, parental exposure to amitriptyline (AMI) has been proven to contribute to congenital disabilities in their offspring. However, no studies have paid attention to the adverse effects of parental exposure to amitriptyline on fish offspring. In this study, we exposed adult zebrafish (F0) to AMI (0.8 μg/L) for 21 days. Subsequently, these zebrafish (F0) were allowed to mate, and their offspring (F1) were collected to culture in clean water for 5 days. The mortality rate, average hatching time, and heart rate at 48 h post-fertilization (hpf) of F1 were investigated. Our results showed that parental exposure to AMI induced tachycardia and increased mortality in F1 zebrafish. Under a light/dark transition test, F1 larvae born from AMI-exposed parents exhibited lower locomotor activity in the dark period and decreased thigmotaxis in the light period. The transcriptome analysis showed that parental AMI exposure dysregulated some key pathways in their offspring. Through the prediction of key driver analysis, six differentially expressed genes (DEGs) were revealed as key driver genes involved in protein processing in endoplasmic reticulum (hspa5, hsp70.1, hsp90a), ribosome (rps27a) and PPAR signaling pathway (pparab and fabp2). Considering that the concentration of AMI residual components in natural water bodies may be over our test concentration (0.8 μg/L), our findings suggested that toxicity of parental exposure to the offspring of fish should receive greater attention.

Reducing Pharmaceuticals in Water, a New Module Integrated in the Pharmacy Game: Evaluating the Module's Effects on Students' Knowledge and Attitudes

Pharmaceutical residues end up in surface waters, impacting drinking water sources and contaminating the aquatic ecosystem. Pharmacists can play a role in reducing pharmaceutical residues, yet this is often not addressed in pharmacy undergraduate education. Therefore, we developed the educational module "Reducing Pharmaceuticals in Water" for pharmacy students; this was integrated in our pharmacy simulation game for third year Master of Pharmacy students at the University of Groningen. In this study, we aim to evaluate the effects of the module on students' knowledge of pharmaceutical residues in water, to describe students' experiences in taking the module, and to explore their attitudes towards green pharmacy education in general. This mixed-methods study included quantitative measurements, before and after students took the module (intervention group) and in a control group which did not receive the module. Data were collected between February 2023 and June 2023. Overall, 29 students took the module and 36 students were in the control group. The knowledge score of students in the intervention group (N = 29) increased significantly from 9.3 to 12.9 out of 22 (p < 0.001). The knowledge score of the students in the control group was (8.9 out of 22). Students found the e-learning and the patient cases the most exciting part of this module. Students also recognized the need to including environmental issues in pharmacy education. In conclusion, the module contributes towards improved knowledge and increased awareness of the impact of pharmaceuticals found in water. It represents a promising strategy to strengthen pharmacist's role in mitigating the amount and the effect of pharmaceuticals on water and the environment in the future.

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.

Delicate plasticity: Maladaptive responses to fish predation risk in Daphnia magna caused by sertraline pollution

An emerging environmental pollutant may have a greater impact on phenotypic plasticity than its direct toxicity, causing maladaptive responses of organisms to their current environment. To better understand such ecological risks, we proposed a delicate plasticity hypothesis: if an emerging stressor acts on the fundamental processes underlying a specific adaptive plastic response, it is more likely to pose high risks to the phenotypic plasticity. Endocrine regulation is one of the critical processes of plasticity and is becoming a target for emerging pollutants. To test this hypothesis, we measured individual traits and the expression of endocrine-related genes in Daphnia magna in response to fish predation risk under exponentially increasing concentrations of the antidepressant sertraline, a selective serotonin reuptake inhibitor. The results showed that sertraline impaired most of the defense responses of D. magna at concentrations lower than the effective concentrations of its direct toxicity. The high risks of sertraline on inducible defenses were also visually reflected in the relationships between toxicity and plasticity strength, that is, most of the defense responses exponentially decayed with an increase in sertraline toxicity. In addition, the expression of genes involved in serotonin synthesis was significantly correlated with the expression of other endocrine-related genes and with changes in morphological traits. These results revealed that environmental sertraline pollution could disturb endocrine regulation and cause high risks to inducible defenses of D. magna, providing evidence supporting the delicate plasticity hypothesis.

Warmer temperature overrides the effects of antidepressants on amphibian metamorphosis and behavior

Climate change can exacerbate the effects of environmental pollutants on aquatic organisms. Pollutants such as human antidepressants released from wastewater treatment plants have been shown to impact life-history traits of amphibians. We exposed tadpoles of the wood frog Lithobates sylvaticus to two temperatures (20 °C and 25 °C) and two antidepressants (fluoxetine and venlafaxine), and measured timing of metamorphosis, mass at metamorphosis, and two behaviors (startle response and percent motionless). Antidepressants significantly shortened time to metamorphosis at 20 °C, but not at 25 °C. At 25 °C, tadpoles metamorphosed significantly faster than those at 20 °C independent of antidepressant exposure. Venlafaxine reduced body mass at 25 °C, but not at 20 °C. Temperature and antidepressant exposure affected the percent of tadpoles showing a startle response. Tadpoles at 20 °C displayed significantly more responses than at 25 °C. Exposure to fluoxetine also increased the percent of tadpoles showing a startle response. Venlafaxine reduced the percent of motionless tadpoles at 25 °C but not at 20 °C. While our results showed that antidepressants can affect the timing of metamorphosis in tadpoles, warmer temperatures overrode these effects and caused a reduction in an important reaction behavior (startle response). Future studies should address how warmer global temperatures may exacerbate or negate the effects of environmental pollutants.

Simultaneous separation and determination of several chiral antidepressants and their enantiomers in wastewater by online heart-cutting two-dimensional liquid chromatography

A novel method for simultaneous separation and detection of the racemates and the enantiomers of common chiral antidepressants in wastewater matrix was developed by online heart-cutting two-dimensional liquid chromatography (2D-LC) coupled to solid-phase extraction (SPE). Screening of chiral stationary phases (CSPs) and chromatographic conditions was investigated for complete enantioseparation to be compatible with RP-HPLC in 1st D-LC. Using methanol-0.1 % (v/v) ammonia solution as mobile phase, a 2D-LC system was configured by reversed mode with a combination of C18 column and the serially CPS columns as 2D-LC stationary phases respectively. The target analytes could achieve satisfactory transformation between 2D-LCs with transfer rate of 90.57-98.58 %. By means of freeze-drying and SPE, three antidepressants in wastewater were greatly preconcentrated under the optimized conditions, improving the method performance. The racemates and the enantiomers of mirtazapine, bupropion and fluoxetine exhibited good linearity in the range of 0.10-30.00 ng/mL (R2≥0.9986), and LODs and LOQs ranged in 0.0183-0.0549 ng/mL and 0.0661-0.1831 ng/mL, respectively. By this way, the method was successfully applied to simultaneous determination of the racemates and the enantiomers of mirtazapine, bupropion and fluoxetine in wastewater samples. Among them, three samples contained bupropion at level of 0.401-0.822 ng/mL, and mirtazapine at level of 0.328 and fluoxetine at level of 0.381 ng/mL were detected respectively in the other two samples. The enantiomers were at level of 0.140-0.189 ng/mL for mirtazapine, 0.182-0.419 ng/mL for bupropion and 0.179-0.204 ng/mL for fluoxetine, respectively. The proposed method providing an efficient approach to monitoring chiral drugs and their enantiomers in wastewater, facilitating to pollution assessment of chiral drugs in the environment and regional survey of illicit abuse in drug control.

Understanding target-specific effects of antidepressant drug pollution on molluscs: A systematic review protocol

BACKGROUND

The environmental prevalence of widely prescribed human pharmaceuticals that target key evolutionary conserved biomolecules present across phyla is concerning. Antidepressants, one of the most widely consumed pharmaceuticals globally, have been developed to target biomolecules modulating monoaminergic neurotransmission, thus interfering with the endogenous regulation of multiple key neurophysiological processes. Furthermore, rising prescription and consumption rates of antidepressants caused by the burgeoning incidence of depression is consistent with increasing reports of antidepressant detection in aquatic environments worldwide. Consequently, there are growing concerns that long-term exposure to environmental levels of antidepressants may cause adverse drug target-specific effects on non-target aquatic organisms. While these concerns have resulted in a considerable body of research addressing a range of toxicological endpoints, drug target-specific effects of environmental levels of different classes of antidepressants in non-target aquatic organisms remain to be understood. Interestingly, evidence suggests that molluscs may be more vulnerable to the effects of antidepressants than any other animal phylum, making them invaluable in understanding the effects of antidepressants on wildlife. Here, a protocol for the systematic review of literature to understand drug target-specific effects of environmental levels of different classes of antidepressants on aquatic molluscs is described. The study will provide critical insight needed to understand and characterize effects of antidepressants relevant to regulatory risk assessment decision-making, and/or direct future research efforts.

METHODS

The systematic review will be conducted in line with the guidelines by the Collaboration for Environmental Evidence (CEE). A literature search on Scopus, Web of Science, PubMed, as well as grey literature databases, will be carried out. Using predefined criteria, study selection, critical appraisal and data extraction will be done by multiple reviewers with a web-based evidence synthesis platform. A narrative synthesis of outcomes of selected studies will be presented. The protocol has been registered in the Open Science Framework (OSF) registry with the registration DOI: 10.17605/OSF.IO/P4H8W.

Effect of psychoactive substances on cardiac and locomotory activity of juvenile marbled crayfish Procambarus virginalis

Pharmaceutically active compounds are common and increasing in the aquatic environment. Evidence suggests they have adverse effects on non-target organisms, and they are classified as emerging pollutants for a variety of aquatic organisms. To determine the effects of environmentally relevant levels of psychoactive compounds on non-target organisms, we analyzed cardiac and locomotory activity in early developmental stages of marbled crayfish Procambarus virginalis. Responses to sertraline, methamphetamine, and a mixture of citalopram, oxazepam, sertraline, tramadol, venlafaxine, and methamphetamine at a concentration of 1 µg L^-1 of each compound were assessed. On day four of exposure, cardiac activity was recorded for 5 min, and on day eight, locomotory activity was recorded for 15 min. There was a significant increase (p < 0.01) in heart rate in methamphetamine-exposed and Mix-exposed juveniles compared to the unexposed control and there was significant difference (p < 0.01) in proportion of time (activity %) was observed with sertraline-exposed, whereas velocity, and distance moved did not significantly differ (p > 0.05) in exposed and control animals. These findings revealed that low concentrations of chemicals and their mixtures can modify the physiological state of aquatic animals without outward manifestations (activity, distance moved, and velocity). Aquatic animals can be impacted earlier than is visible, but effects can potentially lead to substantial changes in populations and in ecosystem processes. Additional research to investigate chemical combinations, exposure systems, and organism physiological and molecular responses may provide evidence of broad impact of environmental pharmaceuticals.

Analyzing the potential environmental impact of NIOSH list of hazardous drugs (group 2)

For the first time, several pharmaceuticals have been defined as priority substances in the new proposal of the revision of the Water Framework Directive (WFD). Consequently, environmental quality standards have been determined for several drugs. This is the case with the antiepileptic carbamazepine, which is considered as hazardous in healthcare settings by The National Institute for Occupational Safety and Health (NIOSH). This organism considers as such drugs that have shown teratogenicity, carcinogenicity, genotoxicity or other developmental, reproductive, or organ toxicity at low doses in studies with animals or humans. This study has been focused on the non-carcinogenic drugs classified in group 2, and their presence in the environment. This group contains many different therapeutic agents such as antineoplastics, psychoactive drugs, immunosuppressants and antivirals, among others. Of the 116 drugs included in the list, 26 have been found in aquatic environmental matrices. Certain drugs have received most attention (e.g., the antiepileptic carbamazepine, progesterone and the antidepressant paroxetine) while others completely lack environmental monitoring. Carbamazepine, fluconazole, paroxetine and warfarin have been found in invertebrates' tissues, whereas carbamazepine, oxazepam and paroxetine have been found in fish tissues. The main aim of the NIOSH's hazardous drug list is to inform healthcare professionals about adequate protection measures to prevent occupational exposure to these pharmaceuticals. However, this list contains useful information for other professionals and researchers such as environmental scientists. The paucity of relevant environmental data of certain hazardous pharmaceuticals might be important to help in the prioritization of compounds that may demand further research.

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.

Investigating Population-Level Toxicity of the Antidepressant Citalopram in Harpacticoid Copepods Using In Vivo Methods and Bioenergetics-Based Population Modeling

Recent research has revealed various lethal and sublethal effects of the selective serotonin reuptake inhibitor citalopram hydrobromide on the harpacticoid copepod Nitocra spinipes. In the present study, an individual-based model (IBM) grounded in the dynamic energy budget (DEB) theory was developed to extrapolate said effects to the population level. Using a generic DEB-IBM as a template, the model was designed to be as simple as possible, keeping model components that are outside the scope of the core DEB theory to a minimum. To test the model, a 56-day population experiment was performed at 0, 100, and 1000 μg citalopram hydrobromide L^-1 . In the experiment, the populations quickly reached a plateau in the control and at 100 μg L^-1 , which was correctly reproduced by the model and could be explained by food limitations hindering further population growth. At 1000 μg L^-1 , a clear mismatch occurred: Whereas in the experiment the population size increased beyond the supposed (food competition-induced) capacity, the model predicted a suppression of the population size. It is assumed that the IBM still misses important components addressing population density-regulating processes. Particularly crowding effects may have played an important role in the population experiment and should be further investigated to improve the model. Overall, the current DEB IBM for N. spinipes should be seen as a promising starting point for bioenergetics-based copepod population modeling, which-with further improvements-may become a valuable individual-to-population extrapolation tool in the future. Environ Toxicol Chem 2023;42:1094-1108. © 2023 SETAC.

An overall assessment of the effects of antidepressant paroxetine on aquatic organisms and human cells

Paroxetine (PRX) is one of the most used antidepressants and an emerging contaminant with potential harmful effects to the environment and human health. The present study investigates in detail the toxic potential of PRX using a battery of bioassays on fresh- and marine species, marine bacteria, and human lymphocytes. All the tested organisms and human lymphocytes were exposed at concentrations ranging from μg L^-1 to mg L^-1. It was found that PRX can cause toxic effects to aquatic organisms at environmental relevant concentrations (μg L^-1 level). A significant effect of PRX was observed in all tested algal species especially at the first 24 h. However, differences in responses and sensitivities among the tested algal species were observed. The most sensitive organism was found to be Dunaliella tertiolecta with IC₅₀ = 0.092 mg L^-1 (72 h). In the case of Aliivibrio fischeri, EC₅₀ values were determined to be 16.65, 14.31 and 14.41 mg L^-1 for 5, 15 and 30 min of exposure, respectively. PRX also induced cytotoxic and genotoxic effects in human lymphocytes. A dose-dependent increase in micronucleus frequencies was occurred at all tested concentrations with a statistically significant increase in micronucleus frequencies at the medium to high PRX tested concentrations. The findings of the present study expand the available toxicity profile of PRX on aquatic organisms and the knowledge about the potential risk of PRX to induce genotoxic effects in cultured human lymphocytes.

Effect of thallium on phototactic behaviour in Daphnia magna

Thallium (Tl) is a trace metal enriched in wastewaters associated with mining and smelting of base metals. The toxicity of Tl to aquatic biota is poorly understood, particularly with respect to its sublethal effects. In this study, phototactic behavioural responses of naïve (i.e. no previous exposure to Tl) Daphnia magna, a key regulatory freshwater crustacean species, were examined in waters containing Tl. Fed and fasted neonate daphnids (< 24 h old) and fed adults (10-15 days old) showed no significant response at any tested water Tl concentration. However, in fasted adults, an increase in the positive phototactic response (measured as a greater number of daphnids closer to the light source after a 5-min exposure) was seen at Tl concentrations of 917 and 2099 µg L-1, values representative of extreme environmental Tl concentrations. The presence of Tl also decreased the swimming speed of adult Daphnia towards a light source. In the presence of cimetidine, a histamine receptor blocker, the increase in positive phototaxis induced by Tl disappeared, suggesting that Tl acts to perturb the phototaxis response through sensory inhibition. Conversely, although there was a trend towards enhanced activity, Tl had no significant effect on acetylcholinesterase, a marker of locomotor capacity.

Levels and effects of antidepressant drugs to aquatic organisms

The use of antidepressants has been increasing globally, resulting in their presence in the aquatic environment, mainly by municipal wastewaters. This fact has aroused concern in the scientific community since these biologically active compounds can affect non-target organisms that have physiological systems regulated by these pharmaceuticals. However, the current knowledge on the toxicological effects of antidepressants on aquatic ecosystems is limited. Considering the increasing consumption pattern, quantification studies and toxicity studies, the present work aimed to review the available literature, published in the last seven years, addressing levels of antidepressants and their metabolites in rivers, surface waters, tap water, and wastewater treatment plants, as well, the effects reported in fish and invertebrates. Overall, the available laboratory studies showed that antidepressants can act at different levels of biological organisation, with detrimental effects at the individual level (e.g., survival, growth, and morphology, behaviour, and reproduction). However, the effects of prolonged exposures to environmentally relevant concentrations of these substances, a more realistic scenario, are unknown. Based on short-term studies, the long-term effects of pharmaceuticals at environmentally relevant concentrations (alone and in the presence of other environmental contaminants) should be studied.

Warmer temperatures limit the effects of antidepressant pollution on life-history traits

Pharmaceutical pollutants pose a threat to aquatic ecosystems worldwide. Yet, few studies have considered the interaction between pharmaceuticals and other chronic stressors contemporaneously, even though the environmental challenges confronting animals in the wild seldom, if ever, occur in isolation. Thermal stress is one such environmental challenge that may modify the threat of pharmaceutical pollutants. Accordingly, we investigated how fluoxetine (Prozac), a common psychotherapeutic and widespread pollutant, interacts with temperature to affect life-history traits in the water flea, Daphnia magna. We chronically exposed two genotypes of Daphnia to two ecological relevant concentrations of fluoxetine (30 ng l^-1 and 300 ng l^-1) and a concentration representing levels used in acute toxicity tests (3000 ng l^-1) and quantified the change in phenotypic trajectories at two temperatures (20°C and 25°C). Across multiple life-history traits, we found that fluoxetine exposure impacted the fecundity, body size and intrinsic growth rate of Daphnia in a non-monotonic manner at 20°C, and often in genotypic-specific ways. At 25°C, however, the life-history phenotypes of individuals converged under the widely varying levels of fluoxetine, irrespective of genotype. Our study underscores the importance of considering the complexity of interactions that can occur in the wild when assessing the effects of chemical pollutants on life-history traits.

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.

Psychoactive drugs citalopram and mirtazapine caused oxidative stress and damage of feeding behavior in Daphnia magna

As the emerging contaminants, the environmental risks of drug-derived pollutants have attracted extensive attention. Citalopram (CTP) and mirtazapine (MTP) are commonly used as modern antidepressant drugs. Previous studies had proved that CTP and MTP entered the aquatic environment, but less reported the negative effects of the drugs on aquatic organisms. Herein, the effects on the feeding rate of Daphnia magna (D. magna) induced by psychotropic drugs CTP and MTP were investigated, which the possible mechanisms were analyzed with the oxidative stress and damage. Generally, the feeding rates of exposed D. magna under all concentrations of CTP and 1.03 mg/L of MTP were significantly decreased after exposure (p < 0.05 or p < 0.01). The inhibitory effect of CTP on the feeding rate of D. magna was time- and dose-dependent. The levels of reactive oxygen species (ROS) were particularly increased in D. magna after CTP and MTP exposure (p < 0.05 or p < 0.01). The level of antioxidant molecules glutathione S-transferase (GST) and the activity of scavenging enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) of D. magna were increased (p < 0.05 or p < 0.01). In consequence, the levels of malondialdehyde (MDA), protein carbonyl, and 8-hydroxydeoxyguanosine (8-OHdG) were increased (p < 0.05 or p < 0.01), which indicated oxidative damage caused by MTP and CTP, due to the imbalance of antioxidative stress system. These findings indicated that psychoactive drugs posed a high toxic threat to the aquatic organisms, and the aquatic environmental risks caused by using psychoactive drugs deserve more attention.

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.

Physiological Roles of Serotonin in Bivalves: Possible Interference by Environmental Chemicals Resulting in Neuroendocrine Disruption

Contaminants of Emerging Concerns (CECs) are defined as chemicals not commonly monitored in aquatic ecosystems, but with the potential to cause adverse effects on biota. CECs include Endocrine Disrupting Chemicals (EDCs) and Neuro-Endocrine disruptors (NEDs) of vertebrates. However, most invertebrates only rely on neuroendocrine systems to maintain homeostatic processes. Although conserved neuroendocrine components have been characterized in ecologically relevant groups, limited knowledge on invertebrate neuroendocrinology makes it difficult to define EDCs and NEDs in most species. The monoamine serotonin (5-hydroxytryptamine, 5-HT) acts both as a neurotransmitter and as a peripheral hormone in mammals. In molluscs, 5-HT is involved in multiple physiological roles and molecular components of the serotonergic system have been identified. This review is focused on the effects of CECs on the serotonergic system of bivalve molluscs. Bivalves are widespread in all aquatic environments, estuarine and coastal areas in particular, where they are exposed to a variety of chemicals. In bivalves, 5-HT is involved in gametogenesis and spawning, oocyte maturation and sperm motility, regulates heart function, gill ciliary beating, mantle/siphon function, the ''catch'' state of smooth muscle and immune responses. Components of 5-HT transduction (receptors and signaling pathways) are being identified in several bivalve species. Different CECs have been shown to affect bivalve serotonergic system. This particularly applies to antidepressants, among the most commonly detected human pharmaceuticals in the aquatic environment. In particular, selective serotonin reuptake inhibitors (SSRIs) are frequently detected in seawater and in bivalve tissues. Information available on the effects and mechanisms of action of SSRIs on the serotonergic system of adult bivalves is summarized. Data are also reported on the effects of CECs on development of neuroendocrine pathways of early larval stages, in particular on the effects of model EDCs in the marine mussel Mytilus galloprovincialis. Overall, available data point at the serotonergic system as a sensitive target for neuroendocrine disruption in bivalves. The results contribute drawing Adverse Outcome Pathways (AOPs) for model EDCs and SSRIs in larvae and adults. However, basic research on neuroendocrine signaling is still needed to evaluate the potential impact of neuroendocrine disruptors in key invertebrate groups of 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.

Transcriptional analyses reveal different mechanism of toxicity for a chronic exposure to fluoxetine and venlafaxine on the brain of the marine fish Dicentrarchrus labrax

Selective serotonin reuptake inhibitor (SSRI) and serotonin norepinephrine reuptake inhibitor (SNRI) are prescribed for clinical depression and detected in aquatic ecosystems. The main aim of this study was to explore and evaluate transcriptional responses of neurotransmitter genes in the brain of a marine fish species, European seabass, and to analyze global brain transcriptomic changes by a RNA-seq technology (MACE, massive analysis of cDNA ends). The juveniles were exposed to two psychopharmaceuticals: (i) fluoxetine (FLX) at the concentration of 0.5 μg/L and 50 μg/L; (ii) venlafaxine (VENX) at the concentration of 0.01 μg/L and 1 μg/L. The exposures were performed for 21 days, followed by a 7-day recovery period to assess the reversibility of effects. Both psychopharmaceuticals affected differentially the neurotransmitter mRNA expression analyzed by RT-qPCR (serotonin receptors: 5-ht3a, 5-ht3b; dopamine receptors: d2, d3; neurotransmitter transporter: sert, vmat; degrading enzyme: mao). Transcriptomic analyses after 21 days of exposure revealed 689 and 632 significant different transcripts by FLX at 0.5 and 50 μg/L, respectively, and 432 and 1250 by VENX at 0.01 and 1 μg/L, respectively, and confirmed different mechanism of toxicity between both compounds. At environmental concentrations, more general pathways including energy metabolism were affected, while at the higher concentration effects on neurotransmitter pathways were observed (FLX: exocytosis and vesicle formation; VENX: small molecule catabolism regulating dopamine and tyrosine level). These results provided new insights into the chronic effects of psychopharmaceutical compounds on marine fish and suggest the need of a separate ecotoxicological risk analysis.

Effects of the anxiolytic benzodiazepine oxazepam on freshwater gastropod reproduction: a prospective study

Psychoactive drugs have emerged as contaminants over the last few decades. These drugs are frequently prescribed and poorly eliminated by wastewater treatment plants, and many are present at non-negligible concentrations in surface waters. Several studies have investigated the non-target organism toxicity of one such drug, oxazepam, a benzodiazepine anxiolytic frequently detected in rivers. However, very little is known about the impact of this drug on reproduction. We investigated the effects of environmentally relevant concentrations of oxazepam on Radix balthica, a freshwater gastropod widespread in Europe. We identified the reproductive organs of Radix balthica. We then exposed this gastropod to oxazepam for two months and assessed several reproductive parameters, from reproductive organ status to behavioral parameters. We found that adults exposed to 10 µg/L oxazepam display an increase in the density of spermatozoa, and that adults exposed to 0.8 µg/L oxazepam displayed a decrease in the number of eggs per egg mass over time. By contrast, oxazepam had no effect on shell length, the size of male reproductive organs or social interactions. Finally, a locomotor activity analysis showed the distance covered over time decreased in all conditions of exposure to oxazepam, potentially reflecting a disturbance of exploratory activity. These results shed light on the effects of oxazepam on the reproduction of a non-target freshwater mollusk.

Pharmaceutical Compounds in Aquatic Environments-Occurrence, Fate and Bioremediation Prospective

Various contaminants of emerging concern (CECs) have been detected in different ecosystems, posing a threat to living organisms and the environment. Pharmaceuticals are among the many CECs that enter the environment through different pathways, with wastewater treatment plants being the main input of these pollutants. Several technologies for the removal of these pollutants have been developed through the years, but there is still a lack of sustainable technologies suitable for being applied in natural environments. In this regard, solutions based on natural biological processes are attractive for the recovery of contaminated environments. Bioremediation is one of these natural-based solutions and takes advantage of the capacity of microorganisms to degrade different organic pollutants. Degradation of pollutants by native microorganisms is already known to be an important detoxification mechanism that is involved in natural attenuation processes that occur in the environment. Thus, bioremediation technologies based on the selection of natural degrading bacteria seem to be a promising clean-up technology suitable for application in natural environments. In this review, an overview of the occurrence and fate of pharmaceuticals is carried out, in which bioremediation tools are explored for the removal of these pollutants from impacted environments.

Temperature, phytoplankton density and bacteria diversity drive the biotransformation of micropollutants in a lake ecosystem

For most micropollutants (MPs) present in surface waters, such as pesticides and pharmaceuticals, the contribution of biotransformation to their overall removal from lake ecosystems is largely unknown. This study aims at empirically determining the biotransformation rate constants for 35 MPs at different periods of the year and depths of a meso-eutrophic lake. We then tested statistically the association of environmental parameters and microbial community composition with the biotransformation rate constants obtained. Biotransformation was observed for 14 out of 35 studied MPs for at least one sampling time. Large variations in biotransformation rate constants were observed over the seasons and between compounds. Overall, the transformation of MPs was mostly influenced by the lake's temperature, phytoplankton density and bacterial diversity. However, some individual MPs were not following the general trend or association with microorganism biomass. The antidepressant mianserin, for instance, was transformed in all experiments and depths, but did not show any relationship with measured environmental parameters, suggesting the importance of specific microorganisms in its transformation. The results presented here contribute to our understanding of the fate of MPs in surface waters and thus support improved risk assessment of contaminants in the environment.

Antidepressants Modify Cryptic Behavior in Juvenile Cuttlefish at Environmentally Realistic Concentrations

Contamination of the marine environment by antidepressants may affect neurophysiological processes in nontarget organisms, such as the common cuttlefish, Sepia officinalis. The present study tested whether environmentally realistic concentrations of antidepressants, that is, fluoxetine alone (5 ng L^-1 ) or cumulated with venlafaxine (2.5 or 5 ng L^-1 ), affect camouflage in newly hatched cuttlefish. The results show that antidepressants improved uniform body patterns, whereas disruptive body patterns were not affected. Environ Toxicol Chem 2021;40:2571-2577. © 2021 SETAC.

Evaluating the effect of fluoxetine on mesophilic anaerobic dark biohydrogen fermentation of excess sludge

Recently, the influence behavior of new pollutants in the environment has been widely concerned. However, the effect of antidepressants widely detected in excess sludge (ES) on biohydrogen production from anaerobic dark fermentation has never been explored. To fill this gap, fluoxetine (FLX), a typical antidepressant, was selected to evaluate its effect on ES mesophilic anaerobic dark biohydrogen fermentation. The results showed that FLX reduced biohydrogen production even at low content (0.1 mg/Kg). The biohydrogen yield was only 12.8 mL/g in the 1.8 mg/Kg (based on total suspended solids) FLX group, decreased by about 34.7%, compared with the control group (without FLX). Further mechanism investigation implied that high levels (more than 0.6 mg/Kg) of FLX reduced every step associated with the biohydrogen production. FLX reduced the concentration of ammonia nitrogen and phosphate in fermentation broth. FLX also had a significant negative effect on enzyme activity in ES dark fermentation.

Pharmacological Modulation of Behaviour, Serotonin and Dopamine Levels in Daphnia magna Exposed to the Monoamine Oxidase Inhibitor Deprenyl

This study assessed the effects of the monoamine oxidase (MAO) inhibitor deprenyl in Daphnia magna locomotor activity. The mechanisms of action of deprenyl were also determined by studying the relationship between behaviour, MAO activity and neurotransmitter levels. Modulation of the D. magna monoamine system was accomplished by 24 h exposure to two model psychotropic pharmaceuticals with antagonistic and agonistic serotonin signalling properties: 10 mg/L of 4-chloro-DL-phenylalanine (PCPA) and 1 mg/L of deprenyl, respectively. Contrasting behavioural outcomes were observed for deprenyl and PCPA reflected in decreased basal locomotor activity and enhanced habituation for the former compound and delayed habituation for the latter one. Deprenyl exposure inhibited monoamine oxidase (MAO) activity and increased the concentrations of serotonin, dopamine and the dopamine metabolite 3-methoxytyramine in whole D. magna extracts. Our findings indicate that D. magna is a sensitive and useful nonvertebrate model for assessing the effects of short-term exposure to chemicals that alter monoamine signalling changes.

Zebrafish as an Animal Model for Testing Agents with Antidepressant Potential

Depression is a serious mental disease that, according to statistics, affects 320 million people worldwide. Additionally, a current situation related to the COVID-19 pandemic has led to a significant deterioration of mental health in people around the world. So far, rodents have been treated as basic animal models used in studies on this disease, but in recent years, Danio rerio has emerged as a new organism that might serve well in preclinical experiments. Zebrafish have a lot of advantages, such as a quick reproductive cycle, transparent body during the early developmental stages, high genetic and physiological homology to humans, and low costs of maintenance. Here, we discuss the potential of the zebrafish model to be used in behavioral studies focused on testing agents with antidepressant potential.

Alteration of predatory behaviour and growth in juvenile cuttlefish by fluoxetine and venlafaxine

Antidepressants in coastal waters may affect ontogeny of predatory behaviour in cuttlefish, which may, as a result, affect growth of newly-hatched cuttlefish. We investigated the effects of two of the most prescribed antidepressants, fluoxetine (FLX) and venlafaxine (VEN) in environmentally realistic concentrations on the predatory behaviour of hatchlings of Sepia officinalis. Newly-hatched cuttlefish were exposed from 1 h (i.e., day 1) to 5 days after hatching to either FLX alone (5 ng·L^-1) or combined with VEN (2.5 ng·L^-1 or 5 ng·L^-1 each) to simulate an environmentally realistic exposure scenario. Their predatory behaviour was analysed through several parameters: prey detection, feeding motivation and success in catching the prey. All parameters improved in control animals over the first five days. The combination of FLX and VEN at 5 ng·L^-1 each altered the predatory behaviour of the hatchlings by increasing the latency before attacking the prey, i.e., reducing feeding motivation, as well as by reducing the number of successful attacks. The changes in predatory behaviour tended to reduce food intake and affected growth significantly at 28 days post-hatching. Exposures to either FLX at 5 ng·L^-1 or FLX and VEN in mixture at 2.5 ng·L^-1 each tended to produce similar effects, even though they were not statistically significant. It is likely that the antidepressants affect maturation of the predatory behaviour and/or learning processes associated with the development of this behaviour. The slightest delay in maturation processes may have detrimental consequences for growth and population fitness.

Neurochemical exposure disrupts sex-specific trade-offs between body length and behaviour in a freshwater crustacean

Ongoing pollution of aquatic ecosystems with neurochemical compounds warrants an improved understanding of how this affects key organisms. Neurochemicals are shown to alter the behaviour of common study species but it remains difficult to translate these results to biologically meaningful predictions across taxa. This is partly because studies on species with non-generic life-history strategies such as many freshwater crustaceans are currently underrepresented. Here, we use a laboratory experiment to assess baseline behavioural variation (spontaneous activity level and geotaxic behaviour) in the freshwater fairy shrimp Branchipodopsis wolfi and how this is affected by chronic exposure to an environmentally-relevant concentration of the anxiolytic pharmaceutical fluoxetine. The more conspicuously coloured and larger females of the species were overall less active and more benthic than males. Moreover, amongst females, vertical activity was negatively associated with size, while an opposite relationship was found for males. These trade-offs are likely part of an antipredator strategy to reduce the probability of being detected by visual hunters, but disappeared after exposure to fluoxetine. This is of particular interest since it is an effective proof of principle that neurochemicals may impact ecologically-relevant trade-offs between conspicuous morphology and antipredator behaviour. In natural ecosystems, such disturbed antipredator behavioural responses could have far-reaching fitness consequences.

Anthropogenic factors associated with contaminants of emerging concern detected in inland Minnesota lakes (Phase II)

Contaminants of emerging concern (CECs) include a variety of pharmaceuticals, personal care products, and hormones commonly detected in surface waters. Human activities, such as wastewater treatment and discharge, contribute to the distribution of CECs in water, but other sources and pathways are less frequently examined. This study aimed to identify anthropogenic activities and environmental characteristics associated with the presence of CECs, previously determined to be of high priority for further research and mitigation, in rural inland lakes in northeastern Minnesota, United States. The setting for this study consisted of 21 lakes located within both the Grand Portage Indian Reservation and the 1854 Ceded Territory, where subsistence hunting and fishing are important to the cultural heritage of the indigenous community. We used data pertaining to numbers of buildings, healthcare facilities, wastewater treatment plants, impervious surfaces, and wetlands within defined areas surrounding the lakes as potential predictors of the detection of high priority CECs in water, sediment, and fish. Separate models were run for each contaminant detected in each sample media. We used least absolute shrinkage and selection operator (LASSO) models to account for both predictor selection and parameter estimation for CEC detection. Across contaminants and sample media, the percentage of impervious surface was consistently positively associated with CEC detection. Number of buildings in the surrounding area was often negatively associated with CEC detection, though nonsignificant. Surrounding population, presence of wastewater treatment facilities, and percentage of wetlands in surrounding areas were positively, but inconsistently, associated with CECs, while catchment area and healthcare centers were generally not associated. The results of this study highlight human activities and environmental characteristics associated with CEC presence in a rural area, informing future work regarding specific sources and transport pathways. We also demonstrate the utility of LASSO modeling in the identification of these important relationships.

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.

Antidepressant Screening Demonstrated Non-Monotonic Responses to Amitriptyline, Amoxapine and Sertraline in Locomotor Activity Assay in Larval Zebrafish

Antidepressants are well-known drugs to treat depression and major depressive disorder for humans. However, the misuse and abuse of antidepressants keep increasing with several side effects reported. The aim of this study was to assess the potential adverse effects of 18 antidepressants by monitoring zebrafish larval locomotor activity performance based on the total distance traveled, burst movement count, and total rotation count at four dark-light intercalated phases. In general, zebrafish larvae displayed sedative effects after antidepressant exposure by showing a significant reduction in all of the locomotor activity-related endpoints. However, three antidepressants i.e., amitriptyline, amoxapine, and sertraline were able to trigger a significantly high locomotor activity in zebrafish larvae during the light cycle. These differences might be due to the pharmacologic differences among the antidepressants. In addition, since each antidepressant possesses a different dosage range from the other, overdoses of these antidepressants might also be the causes of these differences. Furthermore, based on these results, a further study was conducted to observe the effect of these three antidepressants in lower concentrations. From the results, biphasic effects in terms of zebrafish larval locomotor activity were demonstrated by these drugs. Even though further studies are still required to validate the mechanism, these findings indicate that these antidepressants might share a common mechanism responsible for their effects on zebrafish larval locomotor activity although there were some differences in potency of these effects.

Emerging prospects of integrated bioanalytical systems in neuro-behavioral toxicology

Neurotoxicity effects of industrial contaminants are currently significantly under investigated and require innovative analytical approaches to assess health and environmental risks at individual, population and ecosystem levels. Behavioral changes assessed using small aquatic invertebrates as standard biological indicators of the aggregate toxic effects, have been broadly postulated as highly integrative indicators of neurotoxicity with physiological and ecological relevance. Despite recent increase in understanding of the emerging value of behavioral biotests, their wider implementation especially in high-throughput environmental risk assessment assays, is largely limited by the lack of advances in analytical technologies. To date, most of the behavioral biotests have only been performed with larger-volumes and lacked dynamic flow-through conditions. They also lack features necessary for development of higher throughput neuro-behavioral ecotoxicity assays such as miniaturization and integration of automated components. We postulate that some contemporary analytical limitations can be effectively addressed by innovative Lab-on-a-Chip (LOC) technologies, an emerging and multidisciplinary field poised to bring significant miniaturization to aquatic ecotoxicity testing. Recent developments in this emerging field demonstrate particular opportunities to study a plethora of behavioral responses of small model organisms in a high-throughput fashion. In this review, we highlight recent advances in this budding new interdisciplinary field of research. We also outline the existing challenges, barriers to development and provide a future outlook in the evolving field of neurobehavioral ecotoxicology.

Effect of emerging pollutant fluoxetine on the excess sludge anaerobic digestion

Fluoxetine (FLX), an emerging pollutant, has been detected in the sewage and excess sludge (ES) at substantial levels. So far, however, the impacts of FLX on the ES anaerobic digestion and the related mechanisms have never been investigated. In this work, the effects of FLX on the ES anaerobic digestion were explored by the batch test under moderate temperature condition. The results indicated the effect of FLX on ES digestion was dose-dependent. When FLX was at a low dose (0.1 mg/kg), FLX had no significant impact on the methane generation from the ES digestion. However，when FLX was 2.0 mg/kg, the cumulative methane production was only 91.2 ± 4.3 mL/g volatile suspended solids (VSS), which was about 59.9 ± 3.4% of the blank (without FLX). Mechanisms revealed that the presence of FLX has inhibited hydrolysis, acidification and methanogenesis. Enzyme activity analysis showed that FLX inhibited the activities of key enzymes in the process of hydrolysis, acidification and methanogenesis. The results of this work are of great significance to explain the role of FLX in the process of ES fermentation, and provide some reference for the subsequent utilization of ES.

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.

Sertraline inhibits top-down forces (predation) in microbial food web and promotes nitrification in sediment

Sertraline is a widely used antidepressant that becomes an aquatic pollutant through metabolic excretion and improper disposal. Determining the impact of sertraline on benthic microbial ecosystems is important for the transformation of river biogenic elements. However, the molecular initiating event induced by sertraline is more readily observed at higher levels, such as the individual or population level of larger organisms, and the effect is not pronounced in benthic organisms, which are directly involved in nitrogen transformation. Therefore, this study used DNA metabarcoding to analyze the effect of sertraline on the microbial ecosystem and material cycles in river sediment through the lens of a microbial food web. The presence of sertraline in the river sediment enhanced the mineralization capacity of nitrogen and increased the accumulation of nitrate in the sediment. Sertraline affected the structure of the microbial food web by stimulating different successions of bacteria and eukaryotes. A structural equation model revealed that sertraline affected the microbial food web model through top-down forces (predation) by reducing the trophic transfer efficiency from metazoans to protozoans. This effect resulted in decreases in the trophic transfer efficiency from protozoans to bacteria and increases in nitrogen mineralization capacity. This was followed by a gradual increase in the nitrification reaction under the action of nitrifying bacteria, increasing the threat to the ecological health of rivers. The results show that sertraline affects the material cycle of river ecosystems and emphasizes that the assessment of the ecological risks of sertraline needs to be considered from the perspective of the material cycle of ecosystems.

Transgenerational reproductive effects of two serotonin reuptake inhibitors after acute exposure in Daphnia magna embryos

The release of pharmaceuticals and personal care products (PPCPs) into aquatic environments has been a major concern for the health of ecosystems. Transgenerational plasticity is a potential mechanism for organisms to respond to changing environmental conditions, including climate change and environmental contaminants. The purpose of the present study was to determine the long-term transgenerational effects of an abundant freshwater zooplankton, Daphnia magna, to acute embryonic exposures of serotonin re-uptake inhibitors (SSRI - fluoxetine and sertraline). Both SSRIs have been used extensively to treat depression and anxiety disorders for decades and persist in freshwater ecosystems at physiologically relevant concentrations. Our results revealed that even short (72 h) embryonic exposures of D. magna embryos had long lasting consequences on life history and expression of 5HT related genes in the unexposed generation (F3). Moreover, we identified direct effects of SSRIs on heart rate and swimming behavior in the first generation that carried over from embryonic exposure. We also found that SSRI exposure resulted in a transient increase of ephippia formation in the F1 and F2 . Our results suggest that SSRI exposure has transgenerational consequences to the unexposed generation and potentially beyond, even at low concentration (10-100× lower than what can be found in natural ecosystems) and as a result of embryonic exposure. Because of the short reproductive period of D. magna and their integral role in aquatic food webs, these findings have population-level implications and deserve further investigation.

The Effects of Repeated Administration of the Micellar Complex of Methylprednisolone on the Locomotor Activity of a Terrestrial Snails

We studied the effects of repeated injections of methylprednisolone and its micellar complex with block-copolymer on locomotor activity of a terrestrial snail. It was shown that methylprednisolone solution injected into the hemolymph of the animal produced a direct effect on the muscle system of the animal as soon as 1 h after administration: it slowed down snail locomotion and reduced contractile activity of the foot muscles. The micellar complex of methylprednisolone with block-copolymer prevented this effect during the first 2 days of injection and negatively affected locomotion only in 2 days after injection, the decrease in locomotion in this case was not accompanied by a decrease in contractile activity of the foot muscle.

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.

Molecular Methods as Potential Tools in Ecohydrological Studies on Emerging Contaminants in Freshwater Ecosystems

Contaminants of emerging concern (CECs) present a threat to the functioning of freshwater ecosystems. Their spread in the environment can affect both plant and animal health. Ecohydrology serves as a solution for assessment approaches (i.e., threat identification, ecotoxicological assessment, and cause–effect relationship analysis) and solution approaches (i.e., the elaboration of nature-based solutions: NBSs), mitigating the toxic effect of CECs. However, the wide array of potential molecular analyses are not fully exploited in ecohydrological research. Although the number of publications considering the application of molecular tools in freshwater studies has been steadily growing, no paper has reviewed the most prominent studies on the potential use of molecular technologies in ecohydrology. Therefore, the present article examines the role of molecular methods and novel omics technologies as essential tools in the ecohydrological approach to CECs management in freshwater ecosystems. It considers DNA, RNA and protein-level analyses intended to provide an overall view on the response of organisms to stress factors. This is compliant with the principles of ecohydrology, which emphasize the importance of multiple indicator measurements and correlation analysis in order to determine the effects of contaminants, their interaction with other environmental factors and their removal using NBS in freshwater ecosystems.

Oxidative and apoptotic effects of fluoxetine and its metabolite norfluoxetine in Daphnia magna

The aim of this study was to investigate the oxidative and apoptotic potential of fluoxetine, a widely used antidepressant in Turkey and the world, and of its metabolite norfluoxetine on a model non-target organism, Daphnia magna to see how exposure to this group of antidepressants (specific serotonin reuptake inhibitors) could affect the aquatic environment in which they end up. Juvenile D. magna specimens were chronically exposed to fluoxetine and norfluoxetine alone and in combination at concentrations found in the aquatic environment (0.091 and 0.011 μg/L, respectively) and to their 10-fold environmental concentrations for 21 days. Another group of 17-day-old animals were subacutely exposed to 100-fold environmental concentrations for four days. After exposure, we measured their glutathione peroxidase (GPx) and cholinesterase (ChE) activities, thiobarbituric acid-reactive substances (TBARS), and total protein content spectrophotometrically, while mitochondrial membrane potential (MMP) was analysed by fluorescence staining, and cytochrome c and ERK1/2 protein content by Western blotting. This is the first-time cytochrome c and ERK1/2 were determined at the protein level in D. magna. We also measured their carapace length, width, and caudal spine length microscopically. At environmental concentrations fluoxetine and norfluoxetine caused an increase in ChE activity and brood production. They also caused a decrease in juvenile carapace length, width, and caudal spine length and depolarised the mitochondrial membrane. At 10-fold environmental concentrations, GPx activity, lipid peroxidation levels, cytochrome c, and ERK1/2 protein levels rose. The most pronounced effect was observed in D. magna exposed to norfluoxetine. Norfluoxetine also decreased brood production. Similar effects were observed with subacute exposure to 100-fold environmental concentrations. However, total protein content decreased. All this confirms that fluoxetine and norfluoxetine have oxidative and apoptotic potential in D. magna. Daphnia spp. have a great potential to give us precious insight into the mechanisms of environmental toxicants, but there is still a long way to go before they are clarified in these organisms.