Differential behavioural responses to venlafaxine exposure route, warming and acidification in juvenile fish (Argyrosomus regius)

Impacts of anthropogenic pollutants on social group cohesion and individual sociability in fish: A systematic review and meta-analysis

Anthropogenic pollutants are near-ubiquitous in aquatic systems. Aquatic animals such as fishes are subject to physiological stress induced by pollution present in aquatic systems, which can translate to changes in behaviour. Key adaptive behaviours such as shoaling and schooling may be subject to change as a result of physiological or metabolic stress or neurosensory impacts of pollution. This can result in fitness and ecological impacts such as increased predation risk and reduced foraging success. Here, we conducted a systematic metanalysis of the existing literature, comprising 165 studies, on the effects of anthropogenic pollution on sociability and group cohesion in fish species. Both organic (number of studies = 92, posterior mean (PM) = -0.483, p < 0.01) and inorganic (n = 24, PM = -1.453, p < 0.001) chemical pollutants, as well as light exposure (n = 21, PM = -3.038, p < 0.01) were found to reduce sociability. These pollutants did not reduce group cohesion, indicating that effects may be masked in group settings, though fewer studies were carried out on group cohesion and this is a key area for future research. Mixtures of chemical pollutants (n = 16) were found to reduce cohesion (PM = -43.71, p < 0.01), but increase sociability (PM = 44.27, p < 0.01). Evidence was found that fish may behaviourally acclimate to two forms of pollutant, namely mixed chemical pollutants (PM = -0.668, p < 0.01) and noise exposure (n = 22, PM = -4.043, p < 0.01). While aquatic systems are often subject to pollution from multiple sources and of multiple types, very few studies investigated the effects of multiple stressors concurrently. This review identifies trends in the existing literature, and highlights areas where further research is required in order to understand the behavioural and ecological impacts of anthropogenic pollutants in aquatic systems.

Impacts of climate-related stressors on social group cohesion and individual sociability in fish

Group-living in animals comes with a number of benefits associated with predator avoidance, foraging, and reproduction. A large proportion of fish species display grouping behaviour. Fish may also be particularly vulnerable to climate-related stressors including thermal variation, hypoxia, and acidification. As climate-related stressors are expected to increase in magnitude and frequency, any effects on fish behaviour may be increased and affect the ability of fish species to cope with changing conditions. Here we conduct a systematic review of the effects of temperature, hypoxia, and acidification on individual sociability and group cohesion in shoaling and schooling fishes. Searches of the published and grey literature were carried out, and studies were included or excluded based on selection criteria. Data from studies were then included in a meta-analysis to examine broad patterns of effects of climate-related stressors in the literature. Evidence was found for a reduction in group cohesion at low oxygen levels, which was stronger in smaller groups. While several studies reported effects of temperature and acidification, there was no consistent effect of either stressor on sociability or cohesion. There was some evidence that marine fishes are more strongly negatively affected by acidification compared with freshwater species, but results are similarly inconsistent and more studies are required. Additional studies of two or more stressors in combination are also needed, although one study found reduced sociability following exposure to acidification and high temperatures. Overall, there is some evidence that hypoxia, and potentially other climate-related environmental changes, impact sociability and group cohesion in fishes. This may reduce survival and adaptability in shoaling and schooling species and have further ecological implications for aquatic systems. However, this synthesis mainly highlights the need for more empirical studies examining the effects of climate-related factors on social behaviour in fishes.

Antidepressants and COVID-19: Increased use, occurrence in water and effects and consequences on aquatic environment. A review

The COVID-19 pandemic changed the consumption of many drugs, among which antidepressants stand out. This review evaluated the frequency of antidepressant use before and after COVID-19. Once the most consumed antidepressants were identified, detecting a variation in the frequency of consumption on the different continents, an overview of their life cycle was carried out, specifying which antidepressants are mostly detected and the places where there is a greater concentration. In addition, the main metabolites of the most used antidepressants were also investigated. A correlation between the most consumed drugs and the most detected was made, emphasizing the lack of information on the occurrence of some of the most consumed antidepressants. Subsequently, studies on the effects on aquatic life were also reviewed, evaluated through different living beings (fish, crustaceans, molluscs, planktonic crustaceans and algae). Likewise, many of the most used antidepressants lack studies on potential adverse effects on aquatic living beings. This review underscores the need for further research, particularly focusing on the life cycle of the most prescribed antidepressants. In particular, it is a priority to know the occurrence and adverse effects in the aquatic environment of the most used antidepressants after the pandemic.

Pharmaceuticals in biota: The impact of wastewater treatment plant effluents on fish in Australia

Globally, pharmaceuticals and personal care products (PPCPs) are detected in surface waters receiving wastewater, yet their presence in biota, remain largely understudied. To address this, we conducted a study that measured 46 PPCPs in spot water samples and fish caught up- and downstream from wastewater treatment plants (WWTPs) in Victoria, Australia. We sampled 15 sites located along four waterways following a 3-site design: WWTP-discharge('hotspot'), 'upstream'(∼2 km) and 'downstream'(∼2 km). Spot water and fish were also sampled at reference sites >100 km from WWTP discharge (n = 3). Additionally, spot water samples were taken from WWTP effluent outflows (n = 3). From each locality, we analysed 3-12 fish (n = 131 total). In waterways, passive samplers (POCIS; ∼28d, n = 19 PPCPs) were also deployed. Individual fish (axial muscle) and water were analysed with LC-MS-MS. We found that PPCP concentrations in environmental surface water ranged from<0.02-0.97 μg/L. In WWTP effluent, the range was <0.02-1.4 μg/L. Of the 46 PPCPs analysed, 12 were detected in spot water samples and five in fish. In water, the highest concentration detected was for antidepressant venlafaxine (3 μg/L). The most frequently detected PPCPs: venlafaxine (54.9%), metoprolol (41.2%), propranolol (29.4%), carbamazepine (29.4%), caffeine (17.6%) and sulfamethoxazole (17.6%). Out of 131 fish analysed, 35 fish had detectable levels of PPCPs in the muscle tissue. The highest muscle concentrations were: venlafaxine (150 μg/kg, redfin perch), and sertraline (100 μg/kg, eel). Bioaccumulation factors ranged from 104 to 341L/kg for venlafaxine in redfins, 21-1,260L/kg for carbamazepine in redfins and eels, and 367-3,333L/kg for sertraline in eels. Based on our human health risk calculations for venlafaxine, carbamazepine, sertraline, triclosan, and caffeine, consumption of fish does not pose a significant risk to human health. Despite this, most of the detected PPCPs in surface waters exceeded 10 ng/L trigger value, which has led to further investigations by EPA. Our study highlights the need for using multiple lines of evidence for estimating risks of PPCPs.

Identifying pathways of pharmaceutical exposure in a mesoconsumer marine fish

Pharmaceutical uptake involves processes that vary across aquatic systems and biota. However, single studies examining multiple environmental compartments, microhabitats, biota, and exposure pathways in mesoconsumer fish are sparse. We investigated the pharmaceutical burden in bonefish (Albula vulpes), pathways of exposure, and estimated exposure to a human daily dose. To evaluate exposure pathways, the number and composition of pharmaceuticals across compartments and the bioconcentration in prey and bonefish were assessed. To evaluate bioaccumulation, we proposed the use of a field-derived bioaccumulation factor (fBAF), due to variability inherent to natural systems. Exposure to a human daily dose was based on bonefish daily energetic requirements and consumption rates using pharmaceutical concentrations in prey. Pharmaceutical number and concentration were highest in prey, followed by bonefish, water and sediment. Fifteen pharmaceuticals were detected in common among bonefish, prey, and water; all of which bioconcentrated in prey and bonefish, and four bioaccumulated in bonefish. The composition of detected pharmaceuticals was compartment specific, and prey were most similar to bonefish. Bonefish were exposed to a maximum of 1.2 % of a human daily dose via prey consumption. Results highlight the need for multicompartment assessments of exposure and consideration of prey along with water as a pathway of exposure.

Zygotic Exposure to Venlafaxine Disrupts the Circadian Locomotor Activity Behaviour in Zebrafish Larvae

The antidepressant venlafaxine, a selective serotonin and norepinephrine reuptake inhibitor, is commonly prescribed to treat major depressive disorder and is found at high concentrations in the aquatic environment. Concerns have been raised related to the health of aquatic organisms in response to this nontargeted pharmaceutical exposure. For instance, we previously demonstrated that exposure to venlafaxine perturbs neurodevelopment, leading to behavioural alterations in zebrafish (Danio rerio). We also observed disruption in serotonin expression in the pineal and raphe, regions critical in regulating circadian rhythms, leading us to hypothesize that zygotic exposure to venlafaxine disrupts the circadian locomotor rhythm in larval zebrafish. To test this, we microinjected zebrafish embryos with venlafaxine (1 or 10 ng) and recorded the locomotor activity in 5-day-old larvae over a 24-h period. Venlafaxine deposition reduced larval locomotor activity during the light phase, but not during the dark phase of the diurnal cycle. The melatonin levels were higher in the dark compared to during the light photoperiod and this was not affected by embryonic venlafaxine deposition. Venlafaxine exposure also did not affect the transcript abundance of clock genes, including clock1a, bmal2, cry1a and per2, which showed a clear day/night rhythmicity. A notable finding was that exposure to luzindole, a melatonin receptor antagonist, decreased the locomotor activity in the control group in light, whereas the activity was higher in larvae raised from the venlafaxine-deposited embryos. Overall, zygotic exposure to venlafaxine disrupts the locomotor activity of larval zebrafish fish during the day, demonstrating the capacity of antidepressants to disrupt the circadian rhythms in behaviour. Our results suggest that disruption in melatonin signalling may be playing a role in the venlafaxine impact on circadian behaviour, but further investigation is required to elucidate the possible mechanisms in larval zebrafish.

The effect of warming and seasonality on bioaccumulation of selected pharmaceuticals in freshwater invertebrates

Multiple human-induced environmental stressors significantly threaten global biodiversity and ecosystem functioning. Climate warming and chemical pollution are two widespread stressors whose impact on freshwaters is likely to increase. However, little is known about the combined effects of warming on the bioaccumulation of environmentally relevant mixtures of emerging contaminants, such as pharmaceutically active compounds (PhACs) in freshwater biota. This study investigated the bioaccumulation of a mixture of 15 selected PhACs at environmentally relevant concentrations in common freshwater macroinvertebrate taxa, exposed to ambient temperatures and warming (+4 °C) during the warm and cold seasons in two outdoor mesocosm experiments. Nine PhACs (carbamazepine, cetirizine, clarithromycin, clindamycin, fexofenadine, telmisartan, trimethoprim, valsartan and venlafaxine) were dissipated faster in the warm season experiment than in the cold season experiment, while lamotrigine showed the opposite trend. The most bioaccumulated PhACs in macroinvertebrates were tramadol, carbamazepine, telmisartan, venlafaxine, citalopram and cetirizine. The bioaccumulation was taxon, season and temperature dependent, but differences could not be fully explained by the different water stability of the PhACs and their partitioning between water and leaf litter. The highest water-based bioaccumulation factors were found in Asellus and Planorbarius. Moreover, the bioaccumulation of some PhACs increased with warming in Planorbarius, suggesting that it could be used as a sentinel taxon in environmental studies of the effects of climate warming on PhAC bioaccumulation.

New perspectives on the genetic structure of dotted gizzard shad (Konosirus punctatus) based on RAD-seq

To maintain, develop and rationally utilize marine organisms, understanding their genetic structure and habitat adaptation pattern is necessary. Konosirus punctatus, which is a commercial fish species inhabiting the Indo-west Pacific Ocean, has shown an obvious annual global capture and aquaculture production decline due to climate changes and human activities. In the present study, restriction-site associated DNA sequencing (RAD-seq) was used to describe its genome-wide single nucleotide polymorphisms panel (SNPs). Among 146 individuals collected at nine locations scattered in China, Korea and Japan, a set of 632,090 SNPs were identified. Population genetic analysis showed that K. punctatus individuals were divided into two significant genetic clusters. Meanwhile, potential genetic differentiation between northern and southern population of K. punctatus was found. Treemix results indicated that gene flow existed among sampling locations of K. punctatus, especially from southern Japan to others. Moreover, candidate genes associated with habitat adaptations of K. punctatus were identified, which are involved in diverse physiological processes of K. punctatus including growth and development (e.g., KIDINS220, PAN3), substance metabolism (e.g., PGM5) and immune response (e.g., VAV3, CCT7, HSPA12B). Our findings may aid in understanding the possible mechanisms for the population genetic structure and local adaptation of K. punctatus, which is beneficial to establish the management and conservation units of K. punctatus, guiding the rational use of resources, with reference significance for a profound understanding of the adaptative mechanisms of other marine organisms to the environment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-024-00216-2.

Antidepressants and their metabolites primarily affect lysosomal functions in the marine mussel, Mytilus galloprovincialis

Antidepressants widely occur as emerging contaminants in marine coastal waters, with concentrations reported in the low ng/L range. Although at relatively lower levels with respect to other pharmaceuticals, antidepressants - fluoxetine (FLX) in particular - have attracted attention because of their striking effects exerted at low doses on marine invertebrates. In this study, the effects of four antidepressants including FLX, sertraline (SER), and citalopram, as members of the selective serotonin reuptake inhibitor (SSRI) class, and venlafaxine (VEN) as a member of the serotonin and norepinephrine reuptake inhibitor (SNRI) class, were evaluated in the mussel Mytilus galloprovincialis. In addition, the effects of two main metabolites of FLX and VEN, i.e., norfluoxetine (NFL) and O-desmethylvenlafaxine (ODV) respectively, were compared to those of the parent compounds. Eight concentrations of each drug (0.5-500 ng/L range) were tested on the early life stage endpoints of gamete fertilization and larval development at 48 h post fertilization (hpf). Egg fertilization was reduced by all compounds, except for VEN. Larval development at 48 hpf was affected by all SSRIs, but not by SNRIs. The above effects were significant but never exceeded 20 % of control values. Adult mussels were exposed in vivo for 7 days to environmental concentrations of the drugs (0.5, 5, and 10 ng/L) and a battery of eight biomarkers was assessed. Antidepressants primarily targeted lysosomal functions, decreasing haemocyte lysosome membrane stability (up to 70 % reduction) and increasing of the lysosome/cytosol ratio (up to 220 %), neutral lipid (up to 230 %), and lipofuscin (up to 440 %) accumulation in digestive gland. Only SER and NFL significantly affected catalase and glutathione-S-transferase activities in gills and digestive gland. NFL and ODV, were effective and sometimes more active than the parent compounds. All compounds impaired mussel health status, as indicated by the low to high stress levels assigned using the Mussel Expert System.

Effect of Tryptophan Dietary Content on Meagre, Argyrosomus regius, Juveniles Stress and Behavioral Response

There are a high number of stressors present in aquaculture that can affect fish welfare and quality. One way of mitigating stress response is by increasing dietary tryptophan. In this study, three diets containing 0.5% (Tript1), 0.6% (Tript2), and 0.8% (Tript3) of tryptophan were tested in 32 g juvenile meagre for 56 days. At the end of the trial, survival, growth, and proximate composition were similar between treatments. Significant differences were found in the plasma parameters before and after a stress test consisting of 30 s of air exposure. Blood glucose levels were higher in the post-stress for all treatments (e.g., 63.9 and 76.7 mg/dL for Tript1 before and after the stress test), and the hemoglobin values were lower in the post-stress of Tript1 (1.9 g/dL compared to 3.0 and 2.4 g/dL for Tript2 and Tript3, respectively). In terms of behavior, three tests were carried out (novel tank diving and shoaling assays, and lateralization test), but no significant differences were found, except for the number of freezing episodes during the anxiety test (1.4 for Tript3 compared to 3.5 and 4.2 for the other treatments). This study suggests that supplementation with dietary tryptophan, particularly in higher dosage (0.8%), can reduce anxiety-like behavior in meagre exposure to acute stress (novel tank). Although the remaining results showed mild effects, they provide some clues as to the potential of this amino acid as a stress mitigator in aquaculture.

Multi-level toxicity assessment of the antidepressant venlafaxine in embryos/larvae and adults of zebrafish (Danio rerio)

The toxic effects of venlafaxine (VLX) on aquatic organisms have already been verified and therefore are a proven matter of concern. Herein, we evaluated zebrafish embryos/adults after acute exposure to VLX. Embryos/larvae were exposed to different concentrations of VLX (100-1000 mg/L; 1.33 as a dilution factor), to evaluate mortality/developmental changos and to analyze biomarkers (0.002-100 mg/L). For adults, mortality, genotoxicity, and biomarkers were assessed in five different concentrations of VLX (1-100 mg/L). The median lethal concentration (LC50-168h) was 274.1 mg/L for embryos/larvae, and >100 mg/L for adults (LC50-96h). VLX decreased the heart rate frequency and caused premature hatching and lack of equilibrium in embryos/larvae exposed to different concentrations ranging from 100 to 562.5 mg/L. The activity of acetylcholinesterase (AChE) was inhibited in larvae exposed to 1, 25 and 100 mg/L. Glutathione-S-transferase (GST) activity was reduced in both larvae and adults after exposure to different concentrations, mainly at 25 mg/L. For both larvae and adults, lactate dehydrogenase (LDH) activity increased after 100 mg/L of VLX exposure. No DNA damage was observed in peripheral erythrocytes. Exposure to VLX may cause adverse effects on zebrafish in their early and adult life stages, interfering with embryo-larval development, and can induce physiological disturbances in adults.

Risk evaluation and prioritization of contaminants of emerging concern and other organic micropollutants in two river basins of central Argentina

A research gap exists in baseline concentrations of organic micropollutants in South American rivers. Identification of areas with different degrees of contamination and risk to the inhabitant biota is needed to improve management of freshwater resources. Here we inform the incidence and ecological risk assessment (ERA) of current used pesticides (CUPs), pharmaceutical and personal care products (PPCPs) and cyanotoxins (CTX) measured in two river basins from central Argentina (South America). Risk Quotients approach was used for ERA differentiating wet and dry seasons. High risk was associated to CUPs in both basins (45 % and 30 % of sites from Suquía and Ctalamochita rivers, respectively), mostly in the basins extremes. Main contributors to risk in water were insecticides and herbicides in Suquía river and insecticides and fungicides in Ctalamochita river. In Suquía river sediments, a very high risk was observed in the lower basin, mainly from AMPA contribution. Additionally, 36 % of the sites showed very high risk of PCPPs in Suquía river water, with the highest risk downstream the wastewater treatment plant of Córdoba city. Main contribution was from a psychiatric drug and analgesics. In sediments medium risk was observed at the same places with antibiotics and psychiatrics as main contributors. Few data of PPCPs are available in the Ctalamochita river. The risk in water was low, with one site (downstream Santa Rosa de Calamuchita town) presenting moderated risk caused by an antibiotic. CTX represented in general medium risk in San Roque reservoir, with San Antonio river mouth and the dam exit showing high risk during the wet season. The main contributor was microcystin-LR. Priority chemicals for monitoring or further management include two CUPs, two PPCPs, and one CTX, demonstrating a significant input of pollutants to water ecosystems from different sources and the need to include organic micropollutants in current and future monitoring.

The Effects of Short-Term Exposure to pH Reduction on the Behavioral and Physiological Parameters of Juvenile Black Rockfish (Sebastes schlegelii)

Coastal areas are subject to greater pH fluctuation and more rapid pH decline as a result of both natural and anthropogenic influences in contrast to open ocean environments. Such variations in pH have the potential to pose a threat to the survival and physiological function of offshore fishes. With the aim of evaluating the impact of short-term pH reduction on the behavioral performance and physiological response of costal fish, the black rockfish (Sebastes schlegelii), one of the principal stock-enhanced species, was examined. In the present study, juveniles of the black rockfish with a mean body length of 6.9 ± 0.3 cm and weight of 8.5 ± 0.5 g were exposed to a series of pHs, 7.0, 7.2, 7.4, 7.6, 7.8, and normal seawater (pH 8.0) for 96 h. At the predetermined time points post-exposure (i.e., 0, 12, 24, 48, and 96 h), fish movement behavior was recorded and the specimens were sampled to assess their physiological responses. The results indicate that the lowered pH environment (pH 7.0-7.8) elicited a significant increase in highly mobile behavior, a decrease in immobile behavior, and a significant rise in the metabolic levels of the black rockfish juveniles. Specifically, carbohydrate metabolism was significantly elevated in the pH 7.2 and 7.4 treatments, while lipid metabolism was significantly increased in the pH 7.0, 7.4, and 7.8 treatments. The results of the present study indicate that short-term reductions in pH could ramp up boldness and boost energy expenditure in the black rockfish juveniles, leading to an increased metabolic cost. Additionally, the present investigation revealed that the black rockfish juveniles were capable of adapting to a short-term pH reduction. The findings may provide insight into the underlying physiological mechanisms that govern fish responses to potential decreases in seawater pH in the future.

Review of warming and acidification effects to the ecotoxicity of pharmaceuticals on aquatic organisms in the era of climate change

An increase in the temperature and the acidification of the aquatic environment are among the many consequences of global warming. Climate change can also negatively affect aquatic organisms indirectly, by altering the toxicity of pollutants. Models of climate change impacts on the distribution, fate and ecotoxicity of persistent pollutants are now available. For pharmaceuticals, however, as new environmental pollutants, there are no predictions on this issue. Therefore, this paper organizes the existing knowledge on the effects of temperature, pH and both stressors combined on the toxicity of pharmaceuticals on aquatic organisms. Besides lethal toxicity, the molecular, physiological and behavioral biomarkers of sub-lethal stress were also assessed. Both acute and chronic toxicity, as well as bioaccumulation, were found to be affected. The direction and magnitude of these changes depend on the specific pharmaceutical, as well as the organism and conditions involved. Unfortunately, the response of organisms was enhanced by combined stressors. We compare the findings with those known for persistent organic pollutants, for which the pH has a relatively low effect on toxicity. The acid-base constant of molecules, as assumed, have an effect on the toxicity change with pH modulation. Studies with bivalves have been were overrepresented, while too little attention was paid to producers. Furthermore, the limited number of pharmaceuticals have been tested, and metabolites skipped altogether. Generally, the effects of warming and acidification were rather indicated than explored, and much more attention needs to be given to the ecotoxicology of pharmaceuticals in climate change conditions.

Accumulation and metabolization of the antidepressant venlafaxine and its main metabolite o-desmethylvenlafaxine in non-target marine organisms Holothuria tubulosa, Anemonia sulcata and Actinia equina

The assessment of exposure to the antidepressant venlafaxine and its major metabolite o-desmethylvenlafaxine in Holothuria tubulosa, Anemonia sulcata and Actinia equina is proposed. A 28-day exposure experiment (10 μg/L day) followed by a 52-day depuration period was conducted. The accumulation shows a first-order kinetic process reaching an average concentration of 49,125/54342 ng/g dw in H. tubulosa and 64,810/93007 ng/g dw in A. sulcata. Venlafaxine is considered cumulative (BCF > 2000 L/kg dw) in H. tubulosa, A. sulcata and A. equina respectively; and o-desmethylvenlafaxine in A. sulcata. Organism-specific BCF generally followed the order A. sulcata > A. equina > H. tubulosa. The study revealed differences between tissues in metabolizing abilities in H. tubulosa this effect increases significantly with time in the digestive tract while it was negligible in the body wall. The results provide a description of venlafaxine and o-desmethylvenlafaxine accumulation in common and non-target organisms in the marine environment.

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.

Combined effects of climate change and BDE-209 dietary exposure on the behavioural response of the white seabream, Diplodus sargus

Decabromodiphenyl-ether (BDE-209) is a persistent organic pollutant ubiquitously found in marine environments worldwide. Even though this emerging chemical contaminant is described as highly toxic, bioaccumulative and biomagnifiable, limited studies have addressed the ecotoxicological implications associated with its exposure in non-target marine organisms, particularly from a behavioural standpoint. Alongside, seawater acidification and warming have been intensifying their impacts on marine ecosystems over the years, compromising species welfare and survival. BDE-209 exposure as well as seawater acidification and warming are known to affect fish behaviour, but information regarding their interactive effects is not available. In this study, long-term effects of BDE-209 contamination, seawater acidification and warming were studied on different behavioural traits of Diplodus sargus juveniles. Our results showed that D. sargus exhibited a marked sensitivity in all the behaviour responses after dietary exposure to BDE-209. Fish exposed to BDE-209 alone revealed lower awareness of a risky situation, increased activity, less time spent within the shoal, and reversed lateralization when compared to fish from the Control treatment. However, when acidification and/or warming were added to the equation, behavioural patterns were overall altered. Fish exposed to acidification alone exhibited increased anxiety, being less active, spending more time within the shoal, while presenting a reversed lateralization. Finally, fish exposed to warming alone were more anxious and spent more time within the shoal compared to those of the Control treatment. These novel findings not only confirm the neurotoxicological attributes of brominated flame retardants (like BDE-209), but also highlight the relevance of accounting for the effects of abiotic variables (e.g. pH and seawater temperature) when investigating the impacts of environmental contaminants on marine life.

Linking chemical exposure and fish metabolome: Discovering new biomarkers of environmental exposure of Argyrosomus regius to the antidepressant venlafaxine

In this study, a non-target metabolomic approach was used to investigate changes in the metabolome of juvenile meagre (Argyrosomus regius) exposed to venlafaxine (20 µg/L). A total of 24, 22 and 8 endogenous metabolites tentatively identified in liver, brain and plasma, respectively, were significantly changed in venlafaxine exposed meagre, showing tissue-dependent variations in the metabolic profile. The amino acids tryptophan, tyrosine and phenylalanine, which are related to the synthesis, availability, and expression of neurotransmitters (e.g., serotonin, dopamine, epinephrine), showed to be dysregulated by venlafaxine exposure. A high impact was observed in fish brain metabolome that showed a trend of up-regulation for most of the tentatively identified metabolites. In conclusion, the identification of possible biomarkers of exposure in fish metabolome to environmental stressors such as venlafaxine is crucial to assess early signal changes at molecular level, enabling the prevention of deleterious effects at the organism and population levels.

Bioaccumulation/bioconcentration of pharmaceutical active compounds in aquatic organisms: Assessment and factors database

There is increasing evidence that the presence of certain pharmaceuticals in the environment leads to biota exposure and constitute a potential risk for ecosystems. Bioaccumulation is an essential focus of risk assessment to evaluate at what degree emerging contaminants are a hazard both to the environment and the individuals that inhabit it. The main goals of the present review are 1) to summarize and describe the research and factors that should be taken into account in the evaluation of bioaccumulation of pharmaceuticals in aquatic organisms; and 2) to provide a database and a critical review of the bioaccumulation/bioconcentration factors (BAF or BCF) of these compounds in organisms of different trophic levels. Most studies fall into one of two categories: laboratory-scale absorption and purification tests or field studies and, to a lesser extent, large-scale, semi-natural system tests. Although in the last 5 years there has been considerable progress in this field, especially in species of fish and molluscs, research is still limited on other aquatic species like crustaceans or algae. This revision includes >230 bioconcentration factors (BCF) and >530 bioaccumulation factors (BAF), determined for 113 pharmaceuticals. The most commonly studied is the antidepressant group, followed by diclofenac and carbamazepine. There is currently no reported accumulation data on certain compounds, such as anti-cancer drugs. BCFs are highly influenced by experimental factors (notably the exposure level, time or temperature). Field BAFs are superior to laboratory BCFs, highlighting the importance of field studies for reliable assessments and in true environmental conditions. BAF data appears to be organ, species and compound-specific. The potential impact on food web transfer is also considered. Among different aquatic species, lower trophic levels and benthic organisms exhibit relatively higher uptake of these compounds.

Impacts on antioxidative enzymes and transcripts in darter (Etheostoma spp.) brains in the Grand River exposed to wastewater effluent

The Grand River watershed is the largest in southern Ontario and assimilates thirty wastewater treatment plants (WWTP) with varied degrees of treatment. Many WWTPs are unable to effectively eliminate several contaminants of emerging concern (CECs) from final effluent, leading to measurable concentrations in surface waters. Exposures to CECs have reported impacts on oxidative stress measured through antioxidative enzymes (SOD, CAT, GPX). This study focuses on the effects of WWTP effluent on four Etheostoma (Darter) species endemic to the Grand River, by investigating if increased antioxidative response markers are present in darter brains downstream from the effluent outfall compared to an upstream reference site relative to the Waterloo, ON WWTP across two separate years (Oct 2020 and Oct 2021). This was assessed using transcriptional and enzyme analysis of antioxidant enzymes and an enzyme involved in serotonin synthesis, tryptophan hydroxylase (tph). In fall 2020, significant differences in transcript markers were found between sites and sexes in GSD with SOD and CAT showing increased expression downstream, in JD with both sexes showing increased SOD downstream, and an interactive effect for tph in RBD. Changes in transcripts aligned with enzyme activity where interactive effects with sex-related differences were observed in fish collected fall 2020. In contrast, transcripts measured in fall 2021 were increased upstream compared to downstream species in RBD and GSD. This study additionally displayed yearly, species and sex differences in antioxidant responses. Continued investigation on the impacts of CECs in effluent in non-target species is required to better understand WWTP effluent impacts.

Extra food provisioning does not affect behavioural lateralization in nestling lesser kestrels

Costs and benefits of brain lateralization may depend on environmental conditions. Growing evidence indicates that the development of brain functional asymmetries is adaptively shaped by the environmental conditions experienced during early life. Food availability early in life could act as a proxy of the environmental conditions encountered during adulthood, but its potential modulatory effect on lateralization has received little attention. We increased food supply from egg laying to early nestling rearing in a wild population of lesser kestrels Falco naumanni, a sexually dimorphic raptor, and quantified the lateralization of preening behaviour (head turning direction). As more lateralized individuals may perform better in highly competitive contexts, we expected that extra food provisioning, by reducing the level of intra-brood competition for food, would reduce the strength of lateralization. We found that extra food provisioning improved nestling growth, but it did not significantly affect the strength or direction of nestling lateralization. In addition, maternal body condition did not explain variation in nestling lateralization. Independently of extra food provisioning, the direction of lateralization differed between the sexes, with female nestlings turning more often towards their right. Our findings indicate that early food availability does not modulate behavioural lateralization in a motor task, suggesting limited phenotypic plasticity in this trait.

Proximate causes and ultimate effects of common antidepressants, fluoxetine and venlafaxine, on fish behavior

Antidepressant (AD) drugs are widely prescribed for the treatment of psychiatric disorders, including depression and anxiety disorders. The continuous use of ADs causes significant quantities of these bioactive chemicals to enter the aquatic ecosystems mainly through wastewater effluent discharge. This may result in many aquatic organisms being inadvertently affected by these drugs. Fluoxetine (FLX) and venlafaxine (VEN) are currently among the most widely detected ADs in aquatic systems. A growing body of experimental evidence demonstrates that FLX and VEN have a substantial capacity to induce neurotoxicity and cause behavioral dysfunctions in a wide range of teleost species. At the same time, these studies often report seemingly contradictory results that are confounding in nature. Hence, we clearly require comprehensive reviews that attempt to find overarching patterns and establish possible causes for these variable results. This review aims to explore the current state of knowledge regarding the neurobehavioral effects of FLX and VEN on fishes. This study also discusses the potential mechanistic linkage between the neurotoxicity of ADs and behavioral dysfunction and identifies key knowledge gaps and areas for future research.

Detecting behavioural lateralisation in Poecilia reticulata is strongly dependent on experimental design

Abstract

Despite the potential benefits gained from behavioural lateralisation, defined as the asymmetrical expression of cognitive functioning, this trait demonstrates widespread variation within and between populations. Numerous methodologies have been applied to investigate lateralisation, although whether different methodologies give consistent results has been relatively understudied. In this study, we assess (1) the repeatability of individual Poecilia reticulata’s lateralisation indexes between a classic detour assay (I-maze), quasi-circular mirror maze and novel detour assay (a radially symmetric Y-maze); (2) whether the methodological standard of analysing only the first ten turns in a detour assay accurately quantifies lateralisation; and (3) whether lateralisation indexes produced can be adequately explained by random chance by comparing the observed data to a novel unbiased ‘coin-toss’ randomisation model. We found (1) the two detour assays to produce generally consistent results in terms of relative lateralisation (directionality) but differed in terms of absolute laterality (intensity). The mirror assay, however, demonstrated no similarity to either assay. (2) The first ten turns were generally reflective of all turns undertaken during the 15-min trial but reducing the number of turns did exaggerate lateralisation indexes. (3) The observed laterality indexes from the assays were found to be similar to corresponding datasets produced by the randomisation model, with significant deviations likely explained by individuals’ propensity to perform consecutive turns in the same direction. These results demonstrate the need to increase the number of observed turning choices to reduce the likelihood of producing spurious or exaggerated lateralisation indexes from random chance or external influences.

Significance statement

Published studies investigating lateralisation, or ‘handedness’, in fish species have used a diverse array of methodologies. Given the variability in methodologies being employed and the widespread variation in the extent fish are lateralised and in which direction (left or right), it is important to assess whether different methods produce consistent laterality indexes. From assessing individual Poecilia reticulata in three laterality assays, the direction of lateralisation was found to correlate between the two detour assays measuring turn choice, although the absolute strength of this laterality was not consistent. There were no correlations between these assays and in an individual’s eye-use when viewing their reflection in a mirror maze assay. However, further investigation using a novel unbiased ‘coin-toss’ randomisation model to simulate replica datasets for each assay brings into question whether patterns of laterality found in the observed population differ significantly from random chance.

Combined effects of ocean warming and acidification on marine fish and shellfish: A molecule to ecosystem perspective

It is expected that by 2050 human population will exceed nine billion leading to increased pressure on marine ecosystems. Therefore, it is conjectured various levels of ecosystem functioning starting from individual to population-level, species distribution, food webs and trophic interaction dynamics will be severely jeopardized in coming decades. Ocean warming and acidification are two prime threats to marine biota, yet studies about their cumulative effect on marine fish and shellfishes are still in its infancy. This review assesses existing information regarding the interactive effects of global environmental factors like warming and acidification in the perspective of marine capture fisheries and aquaculture industry. As climate change continues, distribution pattern of species is likely to be altered which will impact fisheries and fishing patterns. Our work is an attempt to compile the existing literatures in the biological perspective of the above-mentioned stressors and accentuate a clear outline of knowledge in this subject. We reviewed studies deciphering the biological consequences of warming and acidification on fish and shellfishes in the light of a molecule to ecosystem perspective. Here, for the first time impacts of these two global environmental drivers are discussed in a holistic manner taking into account growth, survival, behavioural response, prey predator dynamics, calcification, biomineralization, reproduction, physiology, thermal tolerance, molecular level responses as well as immune system and disease susceptibility. We suggest urgent focus on more robust, long term, comprehensive and ecologically realistic studies that will significantly contribute to the understanding of organism's response to climate change for sustainable capture fisheries and aquaculture.

Biological effects of the antihypertensive losartan under different ocean acidification scenarios

Since the last decade, several studies have reported the presence and effects of pharmaceutical residues in the marine environment, especially those of the antihypertensive class, such as losartan. However, there is little knowledge about the physiological effects of losartan in marine invertebrates regarding its behavior under possible coastal ocean acidification scenarios. The objective of this study was to evaluate biological effects on marine organisms at different levels of the biological organization caused by the compound losartan in water and sediment under coastal ocean acidification scenarios. Water and sediment samples were collected at five sites around the Santos Submarine Sewage outfall (SSO) and two sites around the Guarujá Submarine Sewage Outfall (GSO). Losartan was found in concentrations ranging from <LOD to 7.63 ng/L in water and from <LOQ to 3.10 ng/g in sediments. Statistical analysis showed interactive effects pH and losartan on the toxicity results. The water toxicity test with Echinometra lucunter embryos/larvae showed LOECs 50-100 mg/L, with values decreasing as the pH decreased. In the sediment assays, LOEC value for sea urchin embryo-larval development was 1.0 μg/g for all tested pHs. Regarding the lysosomal membrane stability assays with adult bivalves, a LOEC of 3000 ng/L was found for Perna perna in water exposure (both at pH 8.0 and 7.6). Effects for Mytella guyanensis were observed at environmentally relevant concentrations in sediment (LOEC = 3 ng/g at pH 8.0 and 7.6). This study demonstrated that coastal ocean acidification by itself causes effects on marine invertebrates, but can also increase the negative effects of losartan in waterborne exposure. There is a need to deepen the studies on the ecotoxicity of pharmaceutical residues and acidification of the marine environment.

The potential for adverse effects in fish exposed to antidepressants in the aquatic environment

Antidepressants are one of the most commonly prescribed pharmaceutical classes for the treatment of psychiatric conditions. They act via modulation of brain monoaminergic signaling systems (predominantly serotonergic, adrenergic, dopaminergic) that show a high degree of structural conservation across diverse animal phyla. A reasonable assumption, therefore, is that exposed fish and other aquatic wildlife may be affected by antidepressants released into the natural environment. Indeed, there are substantial data reported for exposure effects in fish, albeit most are reported for exposure concentrations exceeding those occurring in natural environments. From a critical analysis of the available evidence for effects in fish, risk quotients (RQs) were derived from laboratory-based studies for a selection of antidepressants most commonly detected in the aquatic environment. We conclude that the likelihood for effects in fish on standard measured end points used in risk assessment (i.e., excluding effects on behavior) is low for levels of exposure occurring in the natural environment. Nevertheless, some effects on behavior have been reported for environmentally relevant exposures, and antidepressants can bioaccumulate in fish tissues. Limitations in the datasets used to calculate RQs revealed important gaps in which future research should be directed to more accurately assess the risks posed by antidepressants to fish. Developing greater certainty surrounding risk of antidepressants to fish requires more attention directed toward effects on behaviors relating to individual fitness, the employment of environmentally realistic exposure levels, on chronic exposure scenarios, and on mixtures analyses, especially given the wide range of similarly acting compounds released into the environment.

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.

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

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

Acquiring an evolutionary perspective in marine ecotoxicology to tackle emerging concerns in a rapidly changing ocean

Tens of thousands of anthropogenic chemicals and wastes enter the marine environment each year as a consequence of the ever-increasing anthropogenic activities and demographic growth of the human population, which is majorly concentrated along coastal areas. Marine ecotoxicology has had a crucial role in helping shed light on the fate of chemicals in the environment, and improving our understanding of how they can affect natural ecosystems. However, chemical contamination is not occurring in isolation, but rather against a rapidly changing environmental horizon. Most environmental studies have been focusing on short-term within-generation responses of single life stages of single species to single stressors. As a consequence, one-dimensional ecotoxicology cannot enable us to appreciate the degree and magnitude of future impacts of chemicals on marine ecosystems. Current approaches that lack an evolutionary perspective within the context of ongoing and future local and global stressors will likely lead us to under or over estimations of the impacts that chemicals will exert on marine organisms. It is therefore urgent to define whether marine organisms can acclimate, i.e. adjust their phenotypes through transgenerational plasticity, or rapidly adapt, i.e. realign the population phenotypic performances to maximize fitness, to the new chemical environment within a selective horizon defined by global changes. To foster a significant advancement in this research area, we review briefly the history of ecotoxicology, synthesis our current understanding of the fate and impact of contaminants under global changes, and critically discuss the benefits and challenges of integrative approaches toward developing an evolutionary perspective in marine ecotoxicology: particularly through a multigenerational approach. The inclusion of multigenerational studies in Ecological Risk Assessment framework (ERA) would provide significant and more accurately information to help predict the risks of pollution in a rapidly changing ocean.

Repeatability of lateralisation in mosquitofish Gambusia holbrooki despite evidence for turn alternation in detour tests

Akin to handedness in humans, some animals show a preference for moving to the left or right. This is often attributed to lateralised cognitive functions and eye dominance, which, in turn, influences their behaviour. In fishes, behavioural lateralisation has been tested using detour mazes for over 20 years. Studies report that certain individuals are more likely to approach predators or potential mates from one direction. These findings imply that the lateralisation behaviour of individuals is repeatable, but this is rarely confirmed through multiple testing of each individual over time. Here we quantify the repeatability of turning behaviour by female mosquitofish (Gambusia holbrooki) in a double sided T-maze. Each female was tested three times in each of six treatments: when approaching other females, males, or an empty space; and when able to swim freely or when forced to choose by being herded from behind with a net. Although there was no turning bias based on the mean population response, we detected significant repeatability of lateralisation in five of the six treatments (R = 0.251-0.625). This is noteworthy as we also found that individuals tended to alternate between left and right turns, meaning that they tend to move back and forth along one wall of the double-sided T-maze. Furthermore, we found evidence for this wall following when re-analysing data from a previous study. We discuss potential explanations for this phenomenon, and its implications for study design.

Can ocean warming alter sub-lethal effects of antiepileptic and antihistaminic pharmaceuticals in marine bivalves?

The negative effects induced in marine organisms by Climate Change related abiotic factors consequences, namely ocean warming, are well-known. However, few works studied the combined impacts of ocean warming and contaminants, as pharmaceutical drugs. Carbamazepine (CBZ) and cetirizine (CTZ) occur in the marine environment, showing negative effects in marine organisms. This study aimed to evaluate the impacts of ocean warming on the effects of CBZ and CTZ, when acting individually and combined (drug vs drug), in the edible clam Ruditapes philippinarum. For that, drugs concentration, bioconcentration factors and biochemical parameters, related with clam's metabolic capacity and oxidative stress, were evaluated after 28 days exposure to environmentally relevant scenarios of these stressors. The results showed limited impacts of the drugs (single and combined) at control and warming condition. Indeed, it appeared that warming improved the oxidative status of contaminated clams (higher reduced to oxidized glutathione ratio, lower lipid peroxidation and protein carbonylation levels), especially when both drugs were combined. This may result from clam's defence mechanisms activation and reduced metabolic capacity that, respectively, increased elimination and limited production of reactive oxygen species. At low stress levels, defence mechanisms were not activated which resulted into oxidative stress. The present findings highlighted that under higher stress levels clams may be able to activate defence strategies that were sufficient to avoid cellular damages and loss of redox homeostasis. Nevertheless, low concentrations were tested in the present study and the observed responses may greatly change under increased pollution levels or temperatures. Further research on this topic is needed since marine heat waves are increasing in frequency and intensity and pollution levels of some pharmaceuticals are also increasing in coastal systems.

Environmental levels of venlafaxine impact larval behavioural performance in fathead minnows

Venlafaxine, a selective serotonin and norepinephrine reuptake inhibitor, is one of the most abundant antidepressants in municipal wastewater effluents (MWWE). The early life stages are particularly sensitive to contaminant exposure, but few studies have examined whether persistent exposure to venlafaxine impart adverse developmental outcomes. The fathead minnow (Pimephales promelas) is a widely used model for ecotoxicological studies, and this fish is native to Alberta, Canada. We tested the hypothesis that environmental levels of venlafaxine compromises early developmental behavioural performances in fathead minnows. Embryos were exposed to waterborne venlafaxine at either 0, 0.06, 0.33, 0.66, 1.37 or 3 μg L^-1 concentration for 7 days. Environmental levels of venlafaxine did not impact the survival, hatch rate or heart rate of fathead minnow embryos and larvae but reduced the growth of larvae even at concentrations as low as 0.06 μg L^-1. We validated thigmotaxis as a screen for anxiolytic and anxiogenic behaviour in fathead minnow larvae by exposing them to concentrations of ethanol and caffeine, respectively. Behavioural analyses revealed that early developmental exposure to venlafaxine does not alter thigmotaxis but reduced the activity of fathead minnows. The larval behavioural assays reported here for fathead minnow have the potential to be used as screening tools for the risk assessment of neurotoxic contaminants in MWWE. Overall, we demonstrate for the first time that exposure to environmental levels of venlafaxine during the critical early developmental window does not elicit an anxiogenic response but may adversely affect the larval growth performance of fathead minnows.

Insights on the metabolization of the antidepressant venlafaxine by meagre (Argyrosomus regius) using a combined target and suspect screening approach

Bioaccumulation of pharmaceuticals in fish exposed to contaminated water can be shaped by their capability to metabolize these xenobiotics, affecting their toxicity and animal welfare. In this study the in vivo metabolization of the antidepressant venlafaxine by the juvenile marine fish meagre (Argyrosomus regius) was evaluated using a combined target and suspect screening analytical approach. Thirteen venlafaxine metabolites were identified, namely N-desmethylvenlafaxine and N,N-didesmethylvenlafaxine, which were unequivocally identified using analytical standards, and 11 more tentatively identified by suspect screening analysis, including two Phase II metabolites formed by amino acid conjugation. All of them were detected in the liver, while in plasma and brain only 9 and 6 metabolites, respectively, were detected. Based on these findings, for the first time, a tentative metabolization pathway of venlafaxine by A. regius is proposed. Contrarily to what happen in humans, N-demethylation was identified as the main route of metabolization of venlafaxine by fish. Our findings highlight species-specificity in the metabolization of venlafaxine and allow a better understanding of venlafaxine's toxicokinetic in fish. These results emphasize the need to investigate the biotransformation of xenobiotics by non-target organisms to have an integrated overview of their environmental exposure and to improve future evaluations of environmental risk assessment.

Interacting Effects of Polystyrene Microplastics and the Antidepressant Amitriptyline on Early Life Stages of Brown Trout (Salmo trutta f. fario)

Whether microplastics themselves or their interactions with chemicals influence the health and development of aquatic organisms has become a matter of scientific discussion. In aquatic environments, several groups of chemicals are abundant in parallel to microplastics. The tricyclic antidepressant amitriptyline is frequently prescribed, and residues of it are regularly found in surface waters. In the present study, the influence of irregularly shaped polystyrene microplastics (<50 µm), amitriptyline, and their mixture on early life-stages of brown trout were investigated. In a first experiment, the impacts of 100, 104, and 105 particles/L were studied from the fertilization of eggs until one month after yolk-sac consumption. In a second experiment, eggs were exposed in eyed ova stages to 105, 106 particles/L, to amitriptyline (pulse-spiked, average 48 ± 33 µg/L) or to two mixtures for two months. Microplastics alone did neither influence the development of fish nor the oxidative stress level or the acetylcholinesterase activity. Solely, a slight effect on the resting behavior of fry exposed to 106 particles/L was observed. Amitriptyline exposure exerted a significant effect on development, caused elevated acetylcholinesterase activity and inhibition of two carboxylesterases. Most obvious was the severely altered swimming and resting behavior. However, effects of amitriptyline were not modulated by microplastics.

Heatwave effects on the swimming behaviour of a Mediterranean freshwater fish, the Iberian barbel Luciobarbus bocagei

Heatwaves, which can be defined as increases of at least 5 °C in air temperature for more than five consecutive days for a specified reference period, are expected to become more frequent under the ongoing climate change, with freshwater organisms being particularly vulnerable to high temperature fluctuations. In Mediterranean-climate areas, depending on the extent of summer droughts and loss of longitudinal connectivity, river segments may become isolated, maintaining fish populations confined to a series of disconnected pools, with no possibility to move to thermal refugia and thus becoming more prone to thermal stress. In this study, we evaluated the effect of a simulated heatwave on the swimming behaviour of juvenile stages of a potamodromous native cyprinid fish, the Iberian barbel Luciobarbus bocagei, under experimental mesocosm conditions. Behavioural traits included fish activity, boldness and shoal cohesion and were continuously measured at a constant flow velocity of 18 cm s^-1, which is typical of riffle habitats. Overall, results show that the behaviour of juvenile Iberian barbel is likely to be affected by heatwaves, with fish displaying lower activity and boldness, while no clear difference was observed in shoal cohesion. This study highlights the importance of managing thermal refugia that are crucial for fish to persist in intermittent rivers. Future studies should focus on the interaction of heatwaves with other stressors, such as oxygen depletion, for a broader understanding of the perturbation affecting freshwater fishes under a changing climate.

Psychoactive pharmaceuticals in aquatic systems: A comparative assessment of environmental monitoring approaches for water and fish

Environmental monitoring and surveillance studies of pharmaceuticals routinely examine occurrence of substances without current information on human consumption patterns. We selected 10 streams with diverse annual flows and differentially influenced by population densities to examine surface water occurrence and fish accumulation of select psychoactive medicines, for which consumption is increasing in the Czech Republic. We then tested whether passive sampling can provide a useful surrogate for exposure to these substances through grab sampling, body burdens of young of year fish, and tissue specific accumulation of these psychoactive contaminants. We identified a statistically significant (p < 0.05) relationship between ambient grab samples and passive samplers in these streams when psychoactive contaminants were commonly quantitated by targeted liquid chromatography with tandem mass spectrometry, though we did not observe relationships between passive samplers and tissue specific pharmaceutical accumulation. We further observed smaller lotic systems with elevated contamination when municipal effluent discharges from more highly populated cities contributed a greater extent of instream flows. These findings identify the importance of understanding age and species specific differences in fish uptake, internal disposition, metabolism and elimination of psychoactive drugs across surface water quality gradients.

Elevated CO2 affects anxiety but not a range of other behaviours in juvenile yellowtail kingfish

Elevated seawater CO₂ can cause a range of behavioural impairments in marine fishes. However, most studies to date have been conducted on small benthic species and very little is known about how higher oceanic CO₂ levels could affect the behaviour of large pelagic species. Here, we tested the effects of elevated CO₂, and where possible the interacting effects of high temperature, on a range of ecologically important behaviours (anxiety, routine activity, behavioural lateralization and visual acuity) in juvenile yellowtail kingfish, Seriola lalandi. Kingfish were reared from the egg stage to 25 days post-hatch in a full factorial design of ambient and elevated CO₂ (~500 and ~1000 μatm pCO₂) and temperature (21 °C and 25 °C). The effects of elevated CO₂ were trait-specific with anxiety the only behaviour significantly affected. Juvenile S. lalandi reared at elevated CO₂ spent more time in the dark zone during a standard black-white test, which is indicative of increased anxiety. Exposure to high temperature had no significant effect on any of the behaviours tested. Overall, our results suggest that juvenile S. lalandi are largely behaviourally tolerant to future ocean acidification and warming. Given the ecological and economic importance of large pelagic fish species more studies investigating the effect of future climate change are urgently needed.

Impact of the antidepressant citalopram on the behaviour of two different life stages of brown trout

BACKGROUND

Over the last two decades, there has been a constant increase in prescription rates of antidepressants. In parallel, neuroactive pharmaceuticals are making their way into aquatic environments at increasing concentrations. Among the antidepressants detected in the environment citalopram, a selective serotonin reuptake inhibitor, is one of the most commonly found. Given citalopram is specifically designed to alter mood and behaviour in humans, there is growing concern it can adversely affect the behaviour on non-target wildlife.

METHODS

In our study, brown trout were exposed to citalopram (nominal concentrations: 1, 10, 100, 1000 µg/L) in two different life stages. Larvae were exposed at 7 and 11 °C from the eyed ova stage until 8 weeks post yolk sac consumption, and juvenile brown trout were exposed for 4 weeks at 7 °C. At both stages we measured mortality, weight, length, tissue citalopram concentration, behaviour during exposure and behaviour in a stressfull environment. For brown trout larvae additionally hatching rate and heart rate, and for juvenile brown trout the tissue cortisol concentration were assessed.

RESULTS

During the exposure, both larvae and juvenile fish exposed to the highest test concentration of citalopram (1 mg/L) had higher swimming activity and spent longer in the upper part of the aquaria compared to control fish, which is an indicator for decreased anxiety. Most probably due to the higher swimming activity during the exposure, the juveniles and larvae exposed to 1 mg/L citalopram showed decreased weight and length. Additionally, in a stressful artificial swimming measurement device, brown trout larvae displayed the anxiolytic effect of the antidepressant by reduced swimming activity during this stress situation, already at concentrations of 100 µg/L citalopram. Chemical analysis of the tissue revealed rising citalopram tissue concentrations with rising exposure concentrations. Tissue concentrations were 10 times higher in juvenile fish compared to brown trout larvae. Fish plasma concentrations were calculated, which exceeded human therapeutic levels for the highest exposure concentration, matching the behavioural results. Developmental parameters like hatching rate and heart rate, as well as mortality and tissue cortisol content were unaffected by the antidepressant. Overall, we could trace the pharmacological mode of action of the antidepressant citalopram in the non-target organism brown trout in two different life stages.

Bioconcentration and behavioral effects of four benzodiazepines and their environmentally relevant mixture in wild fish

We studied the adverse effects of four benzodiazepines frequently measured in European surface waters. We evaluated bioaccumulation potential of oxazepam, bromazepam, temazepam, and clobazam in freshwater fish species - perch (Perca fluviatilis) and we conducted a series of behavioral trials to assess their potential to alter boldness, activity, and social behavior. All selected endpoints were studied individually for each target benzodiazepine and as a mixture of all tested compounds to assess possible combinatory effects. We used a three-dimensional automated tracking system to quantify the fish behavior. The four compounds bioconcentrated differently in fish muscle (temazepam > clobazam > oxazepam > bromazepam) at high exposure (9.1, 6.9, 5.7, 8.1 µg L^-1, respectively) and low exposure (0.5, 0.5, 0.3, 0.4 µg L^-1, respectively) concentrations. A significant amount of oxazepam was also measured in fish exposed to temazepam, most likely because of the metabolic transformation of temazepam within the fish. Bromazepam, temazepam, and clobazam significantly affected fish behavior at high concentration, while no statistically significant changes were registered for oxazepam. The studied benzodiazepines affected behavior in combination, because the mixture treatment significantly changed several important behavioral traits even at low concentration, while no single compound exposure had such an effect at that dose. Based on our results, we conclude that effects of pharmaceuticals on aquatic environments could be underestimated if risk assessments only rely on the evaluation of single compounds. More studies focused on the combinatory effects of environmentally relevant mixtures of pharmaceuticals are necessary to fill the gaps in this knowledge.

Behavioural responses of fish groups exposed to a predatory threat under elevated CO2

Most of the studies dealing with the effects of ocean acidification (OA) on fish behaviour tested individuals in isolation, even when the examined species live in shoals in the wild. Here we evaluated the effects of elevated CO₂ concentrations (i.e. ∼900 μatm) on the shelter use and group cohesion of the gregarious damselfish Chromis viridis using groups of sub-adults exposed to a predatory threat. Results showed that, under predatory threat, fish reared at elevated CO₂ concentrations displayed a risky behaviour (i.e. decreased shelter use), whereas their group cohesion was unaffected. Our findings add on increasing evidence to account for social dynamics in OA experiments, as living in groups may compensate for CO₂-induced risky behaviour.

Pharmaceuticals as chemical markers of wastewater contamination in the vulnerable area of the Ebro Delta (Spain)

This study evaluated the occurrence and distribution of 81 pharmaceutically active compounds (PhACs) in the vulnerable area of the Ebro Delta region (Catalonia, Spain), to assess the environmental impact of wastewater treatment plants discharge to coastal environments. The occurrence of PhACs was followed along the wastewater-recipient water-sediment chain until they reach estuaries and the Mediterranean Sea. Water and sediment samples were collected in an integrated way at different sampling points covering three different seasons in reaches of the Ebro River located upstream and downstream from wastewater treatment plants (WWTPs), surrounding channels, estuaries, and the associated receiving seawater. 28 out of the 57 compounds detected in effluent wastewater were positively identified in estuary and seawaters, revealing that WWTP discharges are an important source of contamination in coastal environments and that PhACs are suitable markers of urban contamination in these areas. The substances with the highest frequency of detection belonged to the groups of analgesics/anti-inflammatories (acetaminophen, salicylic acid), antihypertensives (valsartan), psychiatric drugs (carbamazepine), and antibiotics (clarithromycin, trimethoprim). In general, a decrease in concentration was observed from inland sampling points towards the Mediterranean Sea, resulting from a dilution in the recipient marine water bodies. A reduced number of PhACs, at concentrations ranging from 0.1 to 12.5 ng g^-1 dry weight (d.w.) was detected in sediment samples, indicating that sorption is a minor natural attenuation pathway for these compounds. Finally, a prioritization strategy, based on the compounds concentration and frequency of detection in seawater, removal efficiency in WWTP, bioaccumulation potential, toxicity to marine organisms and persistency, was used to highlight the PhACs of major ecological concern and that could be used as relevant indicators of wastewater contamination in coastal environments.

Living in a multi-stressors environment: An integrated biomarker approach to assess the ecotoxicological response of meagre (Argyrosomus regius) to venlafaxine, warming and acidification

Pharmaceuticals, such as the antidepressant venlafaxine (VFX), have been frequently detected in coastal waters and marine biota, and there is a growing body of evidence that these pollutants can be toxic to non-target marine biota, even at low concentrations. Alongside, climate change effects (e.g. warming and acidification) can also affect marine species' physiological fitness and, consequently, compromising their ability to cope with the presence of pollutants. Yet, information regarding interactive effects between pollutants and climate change-related stressors is still scarce. Within this context, the present study aims to assess the differential ecotoxicological responses (antioxidant activity, heat shock response, protein degradation, endocrine disruption and neurotoxicity) of juvenile fish (Argyrosomus regius) tissues (muscle, gills, liver and brain) exposed to VFX (via water or feed), as well as to the interactive effects of warming (ΔT °C = +5 °C) and acidification (ΔpCO₂ ~ +1000 µatm, equivalent to ΔpH = -0.4 units), using an integrated multi-biomarker response (IBR) approach. Overall, results showed that VFX toxicity was strongly influenced by the uptake pathway, as well as by warming and acidification. More significant changes (e.g. increases surpassing 100% in lipid peroxidation, LPO, heat shock response protein content, HSP70/HSC70, and total ubiquitin content, Ub,) and higher IBR index values were observed when VFX exposure occurred via water (i.e. average IBR = 19, against 17 in VFX-feed treatment). The co-exposure to climate change-related stressors either enhanced (e.g. glutathione S-transferases activity (GST) in fish muscle was further increased by warming) or attenuated the changes elicited by VFX (e.g. vitellogenin, VTG, liver content increased with VFX feed exposure acting alone, but not when co-exposed with acidification). Yet, increased stress severity was observed when the three stressors acted simultaneously, particularly in fish exposed to VFX via water (i.e. average IBR = 21). Hence, the distinct fish tissues responses elicited by the different scenarios emphasized the relevance of performing multi-stressors ecotoxicological studies, as such approach enables a better estimation of the environmental hazards posed by pollutants in a changing ocean and, consequently, the development of strategies to mitigate them.

Bioaccumulation and ecotoxicological responses of juvenile white seabream (Diplodus sargus) exposed to triclosan, warming and acidification

Triclosan (TCS) is a synthetic microbial compound widely used in the formulation of various personal care products. Its frequent detection in marine ecosystems, along with its physical and chemical properties, suggest that TCS can be highly persistent, being easily bioaccumulated by biota and, therefore, eliciting various toxicological responses. Yet, TCS's mechanisms of bioaccumulation and toxicity still deserve further research, particularly focusing on the interactive effects with climate change-related stressors (e.g. warming and acidification), as both TCS chemical behaviour and marine species metabolism/physiology can be strongly influenced by the surrounding abiotic conditions. Hence, the aim of this study was to assess TCS bioaccumulation and ecotoxicological effects (i.e. animal fitness indexes, antioxidant activity, protein chaperoning and degradation, neurotoxicity and endocrine disruption) in three tissues (i.e. brain, liver and muscle) of juvenile Diplodus sargus exposed to the interactive effects of TCS dietary exposure (15.9 μg kg^-1 dw), seawater warming (ΔTºC = +5 °C) and acidification (ΔpCO₂ ∼ +1000 μatm, equivalent to ΔpH = -0.4 units). Muscle was the primary organ of TCS bioaccumulation, and climate change stressors, particularly warming, significantly reduced TCS bioaccumulation in all fish tissues. Furthermore, the negative ecotoxicological responses elicited by TCS were significantly altered by the co-exposure to acidification and/or warming, through either the enhancement (e.g. vitellogenin content) or counteraction/inhibition (e.g. heat shock proteins HSP70/HSC70 content) of molecular biomarker responses, with the combination of TCS plus acidification resulting in more severe alterations. Thus, the distinct patterns of TCS tissue bioaccumulation and ecotoxicological responses induced by the different scenarios emphasized the need to further understand the interactive effects between pollutants and abiotic conditions, as such knowledge enables a better estimation and mitigation of the toxicological impacts of climate change in marine ecosystems.

Antidepressants in a changing ocean: Venlafaxine uptake and elimination in juvenile fish (Argyrosomus regius) exposed to warming and acidification conditions

The presence of antidepressants, such as venlafaxine (VFX), in marine ecosystems is increasing, thus, potentially posing ecological and human health risks. The inherent mechanisms of VFX uptake and elimination still require further understanding, particularly accounting for the impact of climate change-related stressors, such as warming and acidification. Hence, the present work aimed to investigate, for the first time, the effects of increased seawater temperature (ΔT°C = +5 °C) and pCO₂ levels (ΔpCO₂ ∼1000 μatm, equivalent to ΔpH = -0.4 units) on the uptake and elimination of VFX in biological tissues (muscle, liver, brain) and plasma of juvenile meagre (Argyrosomus regius) exposed to VFX through two different exposure pathways (via water, i.e. [VFX ] ∼20 μg L^-1, and via feed, i.e. [VFX] ∼160 μg kg^-1 dry weight, dw). Overall, results showed that VFX can be uptaken by fish through both water and diet. Fish liver exhibited the highest VFX concentration (126.7 ± 86.5 μg kg^-1 and 6786.4 ± 1176.7 μg kg^-1 via feed and water exposures, respectively), as well as the highest tissue:plasma concentration ratio, followed in this order by brain and muscle, regardless of exposure route. Both warming and acidification decreased VFX uptake in liver, although VFX uptake in brain was favoured under warming conditions. Conversely, VFX elimination in liver was impaired by both stressors, particularly when acting simultaneously. The distinct patterns of VFX uptake and elimination observed in the different scenarios calls for a better understanding of the effects of exposure route and abiotic conditions on emerging contaminants' toxicokinetics.

Integrated multi-biomarker responses of juvenile seabass to diclofenac, warming and acidification co-exposure

Pharmaceutical drugs, such as diclofenac (DCF), are frequently detected in the marine environment, and recent evidence has pointed out their toxicity to non-target marine biota. Concomitantly, altered environmental conditions associated with climate change (e.g. warming and acidification) can also affect the physiology of marine organisms. Yet, the underlying interactions between these environmental stressors (pharmaceutical exposure and climate change-related stressors) still require a deeper understanding. Comprehending the influence of abiotic variables on chemical contaminants' toxicological attributes provides a broader view of the ecological consequences of climate change. Hence, the aim of this study was to assess the ecotoxicological responses of juvenile seabass Dicenthrachus labrax under the co-exposure to DCF (from dietary sources, 500 ± 36 ng kg^-1 dw), warming (ΔTºC = +5 °C) and acidification (ΔpCO₂ ∼1000 μatm, equivalent to ΔpH = -0.4 units), using an "Integrated Biomarker Response" (IBR) approach. Fish were exposed to these three stressors, acting alone or combined, for 28 days in a full cross-factorial design, and blood, brain, liver and muscle tissues were subsequently collected in order to evaluate: i) animal/organ fitness; ii) hematological parameters and iii) molecular biomarkers. Results not only confirmed the toxicological attributes of dietary exposure to DCF in marine fish species at the tissue (e.g. lower HSI), cellular (e.g. increased ENAs and lower erythrocytes viability) and molecular levels (e.g. increased oxidative stress, protein degradation, AChE activity and VTG synthesis), but also showed that such attributes are altered by warming and acidification. Hence, while acidification and/or warming enhanced some effects of DCF exposure (e.g. by further lowering erythrocyte viability, and increasing brain GST activity and Ub synthesis in muscle), the co-exposure to these abiotic stressors also resulted in a reversion/inhibition of some molecular responses (e.g. lower CAT and SOD inhibition and VTG synthesis). IBRs evidenced that an overall higher degree of stress (i.e. high IBR index) was associated with DCF and warming co-exposure, while the effects of acidification were less evident. The distinct responses observed when DCF acted alone or the animals were co-exposed to the drug together with warming and acidification not only highlighted the relevance of considering the interactions between multiple environmental stressors in ecotoxicological studies, but also suggested that the toxicity of pharmaceuticals can be aggravated by climate change-related stressors (particularly warming), thus, posing additional biological challenges to marine fish populations.