Behavioural ecotoxicology, an "early warning" signal to assess environmental quality

Habitat selection response of the freshwater shrimp Atyaephyra desmarestii experimentally exposed to heterogeneous copper contamination scenarios

In contaminated aquatic ecosystems, it is expected that organisms suffer some effects caused by the contaminants. However, for mobile organisms inhabiting heterogeneously contaminated ecosystems, the continuous exposure to contaminants can be avoided by moving to less contaminated habitats. The present study evaluated the habitat selection of the freshwater shrimp Atyaephyra desmarestii experimentally exposed to different copper concentrations to verify whether the heterogeneous contamination distribution and the connectivity between habitats with different copper levels could generate a random population distribution similar to metapopulation. The experiments were performed in the HeMHAS (Heterogeneous Multi-Habitat Assay System), a non-forced multi-compartmented exposure system, in which it is possible to simulate the distribution of contaminants in a linear gradient or as patches of contamination. Copper was used to simulate a linear contamination gradient (26 to 105 μg/L Cu) and two patchy scenarios with three contamination levels [reference zone (R: 26 ± 7 μg/L Cu), mixing zone (M: 61 ± 2 μg/L Cu) and disturbed zone (D: 101 ± 12 μg/L Cu)], with two mixing zones or one central mixing zone in a heterogeneous scenario. In the copper gradient scenario, a clear trend of shrimps (59.6 ± 8.0% of the population) moving to the reference zones and an avoidance of 66.7 ± 11.1% of the most contaminated zone were observed. For the patchy scenarios, a random distribution of organisms (34, 36 and 30% for R, M and D zones, respectively) was observed in the scenario with one mixing zone; on the other hand, a slight preference for the reference zones (44.9 ± 4.8%) was evidenced in the scenario with two mixing zones. As shrimps are able to select less contaminated areas, it is highly important to preserve clean zones in heterogeneously contaminated environments, such as the arrangement in meta-ecosystems, as the less- or uncontaminated zones might represent less stressful areas to protect populations against continuous contamination exposure.

No Effect of Polystyrene Microplastics on Foraging Activity and Survival in a Post-larvae Coral-Reef Fish, Acanthurus triostegus

Microplastics (MP) are ubiquitous in the marine environment and have been shown to alter the behaviour of some species due to potential neurotoxic effect. However, very little is known on the effect of this stressor on behavioural responses of early and more vulnerable life stages. This study explores the effects of polystyrene MP (90 µm diameter) on the foraging activity of newly settled surgeonfish Acanthurus triostegus and on their survival facing predators. Exposure to a high concentration of 5 MP particles per mL (5 MP mL^-1) for 3, 5 and 8 days did not alter their foraging activity nor their susceptibility to predation. This suggests that short-term exposures to reportedly high MP concentrations have negligible effects on the behaviour of newly settled A. triostegus. Nevertheless, responses to MP can be highly variable, and further research is needed to determine potential ecological effects of MP on reef fish populations during early-life stages.

Disturbance of ecological habitat distribution driven by a chemical barrier of domestic and agricultural discharges: An experimental approach to test habitat fragmentation

Contamination is an important factor for determining the pattern of habitat selection by organisms. Since many organisms are able to move from contaminated to more favorable habitats, we aimed to: (i) verify if the contamination along the river Guadalete (Spain) could generate a chemical barrier, restricting the displacement of freshwater shrimps (Atyaephyra desmarestii) and (ii) discriminate the role of the contaminants concerning the preference response by the shrimps. A. desmarestii was experimentally tested in a multi-compartmented, non-forced exposure system, simulating the spatial arrangement of the samples just like their distribution in the environment. Water and sediment samples were chemically characterized by analyses of 98 chemical compounds and 19 inorganic elements. Shrimps selected the less contaminated water and sediment samples, with two marked preference patterns: (i) upstream displacement avoiding the sample located at the point of pollutant discharges and those samples downstream from this point and (ii) fragmentation of the population with spatial isolation of the upstream and downstream populations. The preference was related to the avoidance of artificial sweeteners, flame retardants, fragrances, PAHs, PCBs, pesticides, UV filters and some inorganic elements. The threat of contamination was related to its potential to isolate populations due to the chemical fragmentation of their habitat.

Fish on steroids: Temperature-dependent effects of 17β-trenbolone on predator escape, boldness, and exploratory behaviors

Hormonal growth promoters (HGPs), widely used in beef cattle production globally, make their way into the environment as agricultural effluent-with potential impacts on aquatic ecosystems. One HPG of particular concern is 17β-trenbolone, which is persistent in freshwater habitats and can affect the development, morphology and reproductive behaviors of aquatic organisms. Despite this, few studies have investigated impacts of 17β-trenbolone on non-reproductive behaviors linked to growth and survival, like boldness and predator avoidance. None consider the interaction between 17β-trenbolone and other environmental stressors, such as temperature, although environmental challenges confronting animals in the wild seldom, if ever, occur in isolation. Accordingly, this study aimed to test the interactive effects of trenbolone and temperature on organismal behavior. To do this, eastern mosquitofish (Gambusia holbrooki) were subjected to an environmentally-relevant concentration of 17β-trenbolone (average measured concentration 3.0 ± 0.2 ng/L) or freshwater (i.e. control) for 21 days under one of two temperatures (20 and 30 °C), after which the predator escape, boldness and exploration behavior of fish were tested. Predator escape behavior was assayed by subjecting fish to a simulated predator strike, while boldness and exploration were assessed in a separate maze experiment. We found that trenbolone exposure increased boldness behavior. Interestingly, some behavioral effects of trenbolone depended on temperature, sex, or both. Specifically, significant effects of trenbolone on male predator escape behavior were only noted at 30 °C, with males becoming less reactive to the simulated threat. Further, in the maze experiment, trenbolone-exposed fish explored the maze faster than control fish, but only at 20 °C. We conclude that field detected concentrations of 17β-trenbolone can impact ecologically important behaviors of fish, and such effects can be temperature dependent. Such findings underscore the importance of considering the potentially interactive effects of other environmental stressors when investigating behavioral effects of environmental contaminants.

Environmental risk assessment of psychoactive drugs in the aquatic environment

The consumption of psychoactive pharmaceuticals has increased worldwide, and wastewater treatment plants are not able to eliminate them from the effluent. An extensive review was carried out to assess the environmental risk (ERA model) based on secondary data about potential impacts on non-target organisms of seven psychoactive drugs consumed worldwide (alprazolam, bromazepam, citalopram, clonazepam, diazepam, lorazepam, and oxazepam). Risk quotients (RQs) were calculated according to the European Medicines Agency (EMA) on ERA of Medicinal Products For Human Use based on (i) the predicted and measured environmental concentrations (PEC and MEC, respectively) of the psychoactive drug in surface water, groundwater, and wastewater effluent and (ii) the predicted no-effect concentration (PNEC) derived from ecotoxicological assays or ECOSAR software. Furthermore, this study reviews and discusses non-standardized ecotoxicity assays, such as sublethal and behavioral effects on different organisms. In total, 903 MEC entries of psychoactive drugs and 162 data on ecotoxicological assays were gathered from the literature survey addressing behavioral effects (115), acute/chronic effects (35), and sublethal effects (12). Citalopram and diazepam were the only substances that are likely to pose an environmental risk (RQ > 1) to surface waters. Even though there is considerable amount of data on behavioral effects of psychoactive drugs to aquatic species, results are currently not integrated into the EMA risk assessment framework. The large amount of data on psychoactive drug concentrations and effects on non-target organisms collected, interpreted, and discussed in the present study should be used as a baseline for future improvement of ERA strategies.

Embryonic exposure to environmentally relevant concentrations of triclosan impairs foraging efficiency in zebrafish larvae

The ubiquitous and persistent contaminant triclosan is known to cause developmental and behavioral toxicity in fish, but few studies have evaluated the long-term effects of these responses. We used a phenotypically anchored approach to evaluate the behavioral responses caused by early exposure to environmentally relevant concentrations of triclosan to better understand the risk triclosan poses to fish. Zebrafish were exposed to 0, 0.4, 4, or 40 μg triclosan/L (nominal concentrations) for 5 d followed by depuration for 16 d to assess effects on mortality, development, and foraging efficiency. Because foraging efficiency can be impacted by neurological and structural alterations, we assessed morphological and behavioral indicators of neurotoxicity and morphology of craniofacial features associated with gape to identify potential underlying mechanisms associated with altered foraging behaviors. To our knowledge, we are the first to show that early exposure to environmentally relevant concentrations of triclosan impairs foraging efficiency in larval fish by 10%, leading to emaciation and reduced growth and survival. The cause of the impacts of triclosan on foraging efficiency remains unknown, because effects were not associated with overt indicators of neurotoxicity or grossly malformed craniofacial structures. Our results suggest that early exposure to triclosan has the potential to impact the sustainability of wild fish populations, and thus the mechanism underlying behavioral alterations following exposure to triclosan warrants further study. Environ Toxicol Chem 2018;37:3124-3133. © 2018 SETAC.

Behavioral responses and starvation survival of Daphnia magna exposed to fluoxetine and propranolol

Fluoxetine and propranolol are neuroactive human pharmaceuticals that occur frequently as pollutants in surface waters. The potential effects of these pharmaceuticals on aquatic organisms have raised concern but many adverse effects are not well characterized for a broad range of concentrations and endpoints. In this study, 6 biological parameters in the freshwater Cladoceran Daphnia magna were compared for their responses to fluoxetine or propranolol exposure: mobility (dichotomous response), active swimming time, swimming distance, swimming velocity, swimming acceleration speed, and survival in the absence of food (starvation-survival). Changes in swimming behavior was quantified by video tracking followed by image analyses at six exposure concentrations between 100 ng/L and 10 mg/L. Active swimming time and swimming distance were the most responsive parameters among the behavioral traits. Sublethal exposure concentrations resulted in nonmonotonic responses and behavior profiling suggested that fluoxetine and propranolol stimulated swimming activity at 1-10 μg/L whereas lower (0.1-1 μg/L) and higher exposure concentrations (>100 μg/L) inhibited swimming activity. The ability to survive in the absence of food when exposed to fluoxetine or propranolol resulted in EC50 and EC10 values that were lower than for swimming behavior (EC50 of 0.79-0.99 mg/L; EC10 of 1.4-2.9 μg/L). Starvation-survival appeared to be a potentially simple and sensitive endpoint for adverse effects in D. magna at intermediate exposure concentrations. Nonmonotonic behavioral responses at low exposure concentrations and decreased ability to survive starvation should be considered in assessment of adverse effects of pharmaceuticals to freshwater invertebrates.

Behavioral effects of the neurotoxin -N-methylamino- L-alanine on the mangrove rivulus (Kryptolebias marmoratus) larvae

Mangrove rivulus, Kryptolebias marmoratus, is a hermaphrodite fish capable of self-fertilization. This particularity allows to naturally produce highly homozygous and isogenic individuals. Despite the low genetic diversity, rivulus can live in extremely variable environments and adjust its phenotype accordingly. This species represents a unique opportunity to clearly distinguish the genetic and non-genetic factors implicated in adaptation and evolution, such as epigenetic mechanisms. It is thus a great model in aquatic ecotoxicology to investigate the effects of xenobiotics on the epigenome, and their potential long-term impacts. In the present study, we used the mangrove rivulus to investigate the effects of the neurotoxin b-N-methylamino-L-alanine (BMAA) on larvae behaviors after 7 days exposure to two sub-lethal concentrations. Results show that BMAA can affect the maximal speed and prey capture (trials and failures), suggesting potential impacts on the organism’s fitness.

Escherichia coli's water load affects zebrafish (Danio rerio) behavior

Traditional physico-chemical sensors are becoming an obsolete tool for environmental quality assessment. Biomonitoring techniques, such as biological early warning systems present the advantage of being sensitivity, fast, non-invasive and ecologically relevant. In this work, we applied a video tracking system, developed with zebrafish (Danio rerio), to detect microbiological contamination in water. Using the fishs' behavior response, the system was able to detect the presence of a non-pathogenic environmental strain of Escherichia coli, at three different levels of contamination: 600, 1800 and 5000 CFU/100 mL (colony forming units/100 mL). Data was collected during 50 min of exposure and analyzed with the artificial neural networks Self-organizing Map and Multi-layer Perceptron. The behavior of exposed fish was more erratic, with pronounced and rapid changes on movement direction and with significant less exploratory activity. The accuracy, sensitivity and specificity values regarding the detection capability (distinction between presence or absence of contamination) ranged from 89 to 100%. Regarding the classification capability (distinction between experimental conditions), the values ranged from 67 to 89%. This research may be a valuable contribution to improve water monitoring and management strategies, by taking as reference the effects on biosensors, without a biased anthropocentric perspective.

Direct and indirect effects of chemical contaminants on the behaviour, ecology and evolution of wildlife

Chemical contaminants (e.g. metals, pesticides, pharmaceuticals) are changing ecosystems via effects on wildlife. Indeed, recent work explicitly performed under environmentally realistic conditions reveals that chemical contaminants can have both direct and indirect effects at multiple levels of organization by influencing animal behaviour. Altered behaviour reflects multiple physiological changes and links individual- to population-level processes, thereby representing a sensitive tool for holistically assessing impacts of environmentally relevant contaminant concentrations. Here, we show that even if direct effects of contaminants on behavioural responses are reasonably well documented, there are significant knowledge gaps in understanding both the plasticity (i.e. individual variation) and evolution of contaminant-induced behavioural changes. We explore implications of multi-level processes by developing a conceptual framework that integrates direct and indirect effects on behaviour under environmentally realistic contexts. Our framework illustrates how sublethal behavioural effects of contaminants can be both negative and positive, varying dynamically within the same individuals and populations. This is because linkages within communities will act indirectly to alter and even magnify contaminant-induced effects. Given the increasing pressure on wildlife and ecosystems from chemical pollution, we argue there is a need to incorporate existing knowledge in ecology and evolution to improve ecological hazard and risk assessments.

Comparison of the behavioural effects of pharmaceuticals and pesticides on Diamesa zernyi larvae (Chironomidae)

Several studies have indicated the presence of contaminants in Alpine aquatic ecosystems. Even if measured concentrations are far below those that cause acute effects, continuous exposure to sub-lethal concentrations may have detrimental effects on the aquatic species present in these remote environments. This may lead to a cascade of indirect effects at higher levels of the ecological hierarchy (i.e., the community). To improve the determination of ecologically relevant risk endpoints, behavioural alterations in organisms due to pollutants are increasingly studied in ecotoxicology. In fact, behaviour links physiological function with ecological processes, and can be very sensitive to environmental stimuli and chemical exposure. This is the first study on behavioural alteration in a wild population of an Alpine species. In the present study, a video tracking system was standardized and subsequently used to identify contaminant-induced behavioural alterations in Diamesa zernyi larvae (Diptera, Chironomidae). Diamesa zernyi larvae, collected in an Italian Alpine stream (Rio Presena, Trentino Region), were acclimated for 24 h and successively exposed to several aquatic contaminants (pesticides: chlorpyrifos, metolachlor, boscalid, captan; pharmaceuticals: ibuprofen, furosemide, trimethoprim) at concentrations corresponding to their Lowest Observed Effect Concentration (LOEC). After 24, 48, 72, and 96 h of exposure, changes in the distance moved, the average speed, and the frequency of body bends were taken to reflect contaminant- and time-dependent effects on larval behaviour. In general, metolachlor, captan, and trimethoprim tended to reduce all the endpoints under consideration, whereas chlorpyrifos, boscalid, ibuprofen, and furosemide seemed to increase the distances moved by the larvae. This could be related to the different mechanisms of action of the investigated chemicals. Independently of the contaminant, after 72 h a general slowing down of all the behavioural activities occurred. Finally, we propose a behavioural stress indicator to compare the overall behavioural effects induced by the various contaminants.

Caging of planktonic rotifers in microfluidic environment for sub-lethal aquatic toxicity tests

Quantification of neuro-behavioural responses of intact small model organisms has been proposed as a sensitive, sub-lethal alternative to conventional toxicity testing. Such bioassays are characterized by a high physiological and ecological relevance, short response times, increased sensitivity, and non-invasive nature. Despite a significant potential for predictive aquatic toxicology analysis of behavioural traits of micro-invertebrates in microfluidic environment has received little attention. In this work, we demonstrate a new Lab-on-a-Chip technology capable of effectively caging freshwater rotifers Brachionus calyciflorus for real-time video-microscopy analysis. We demonstrate that behavioural bioassays performed under microfluidic perfusion can significantly enhance the sensitivity of conventional ecotoxicology test protocols.

Prey Foraging Under Sublethal Lambda-Cyhalothrin Exposure on Pyrethroid-Susceptible and -Resistant Lady Beetles (Eriopis connexa (Coleoptera: Coccinelidae))

Sublethal insecticide exposure may affect foraging of insects, including natural enemies, although the subject is usually neglected. The lady beetle Eriopis connexa (Germar, 1824) (Coleoptera: Coccinelidae) is an important predator of aphids with existing pyrethroid-resistant populations that are undergoing scrutiny for potential use in pest management systems characterized by frequent insecticide use. However, the potential effect of sublethal pyrethroid exposure on this predator's foraging activity has not yet been assessed and may compromise its use in biological control. Therefore, our objective was to assess the effect of sublethal lambda-cyhalothrin exposure on three components of the prey foraging activity (i.e., walking, and prey searching and handling), in both pyrethroid-susceptible and -resistant adults of E. connexa. Both lady beetle populations exhibited similar walking patterns without insecticide exposure in noncontaminated arenas, but in partially contaminated arenas walking differed between strains, such that the resistant insects exhibited greater walking activity. Behavioral avoidance expressed as repellence to lambda-cyhalothrin was not observed for either the susceptible or resistant populations of E. connexa, but the insecticide caused avoidance by means of inducing irritability in 40% of the individuals, irrespective of the strain. Insects remained in the insecticide-contaminated portion of the arena for extended periods resulting in greater exposure. Although lambda-cyhalothrin exposure did not affect prey searching by susceptible lady beetles, prey searching was extended for exposed resistant predators. In contrast, prey handling was not affected by population or by lambda-cyhalothrin exposure. Thus, sublethal exposure to the insecticide in conjunction with the insect resistance profile can affect prey foraging with pyrethroid-exposed resistant predators exhibiting longer prey searching time associated with higher walking activity reducing its predatory performance.

Reducing the Number of Individuals to Monitor Shoaling Fish Systems - Application of the Shannon Entropy to Construct a Biological Warning System Model

The present study aims at identifying the lowest number of fish (European seabass) that could be used for monitoring and/or experimental purposes in small-scale fish facilities by quantifying the effect that the number of individuals has on the Shannon entropy (SE) of the trajectory followed by the shoal’s centroid. Two different experiments were performed: (i) one starting with 50 fish and decreasing to 25, 13, and 1 fish, and (ii) a second experiment starting with one fish, adding one new fish per day during 5 days, ending up with five fish in the tank. The fish were recorded for 1h daily, during which time a stochastic event (a hit in the tank) was introduced. The SE values were calculated from the images corresponding to three arbitrary basal (shoaling) periods of 3.5 min prior to the event, and to the 3.5 min period immediately after the event (schooling response). Taking both experiments together, the coefficient of variation (CV) of the SE among measurements was largest for one fish systems (CV 37.12 and 17.94% for the daily average basal and response SE, respectively) and decreased concomitantly with the number of fish (CV 8.6–10% for the basal SE of 2 to 5 fish systems and 5.86, 2.69, and 2.31% for the basal SE of 13, 25, and 50 fish, respectively). The SE of the systems kept a power relationship with the number of fish (basal: R²= 0.93 and response: R²= 0.92). Thus, 5–13 individuals should be the lowest number for a compromise between acceptable variability (<10%) in the data and reduction in the number of fish. We believe this to be the first scientific work made to estimate the minimum number of individuals to be used in subsequent experimental (including behavioral) studies using shoaling fish species that reaches a compromise between the reduction in number demanded by animal welfare guidelines and a low variability in the fish system’s response.

Microplastic does not magnify the acute effect of PAH pyrene on predatory performance of a tropical fish (Lates calcarifer)

Microplastic (MP) leads to widespread pollution in the marine ecosystem. In addition to the physical hazard posed by ingestion of microplastic particles, concern is also on their potential as vector for transport of hydrophobic contaminants. We experimentally studied the single and interactive effects of microplastic and pyrene, a polycyclic aromatic hydrocarbon, on the swimming behaviour and predatory performance of juvenile barramundi (Lates calcarifer). Juveniles (18+ days post hatch) were exposed to MPs, or pyrene (100 nM), or combination of both, and feeding rate and foraging activity (swimming) were analysed. Exposure to MPs alone did not significantly influence feeding performance of the juveniles, while a dose-effect series of pyrene showed strong effect on fish behaviour when concentrations were above 100 nM. In the test of combined MP and pyrene exposure, we observed no effect on feeding while swimming speed decreased significantly. Thus, our results confirm that short-time exposure to pyrene impacts the performance of fish juveniles, while additional exposure to microplastic at the given conditions influenced their activity only and not their feeding rate. Further studies of the combined effects of microplastics and pollutants on tropical fish behaviour are encouraged.

Sublethal effects of four insecticides on folding and spinning behavior in the rice leaffolder, Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae)

BACKGROUND

The rice leaffolder, Cnaphalocrocis medinalis, is an important rice pest. The sublethal effects of chlorpyrifos, chlorantraniliprole, emamectin benzoate and spinosad were investigated on the folding and spinning behaviors of third- to fifth-instar C. medinalis larvae (L3 - L5) after insecticidal exposure of the second instar.

RESULTS

A 25% lethal concentration (LC₂₅ ) of chlorpyrifos prolonged the leaf selection time of L5, and reduced the number of binds per primary fold for L4 and L5. An LC₁₀ of chlorantraniliprole reduced the number of binds per primary fold for L4 and increased the number of head swings per bind for L5. An LC₁₀ of emamectin benzoate shortened the primary fold length for L5 and decreased the number of head swings per primary fold for L3 and L4 and the number of head swings per bind for L3, while an LC₂₅ of emamectin benzoate shortened the fold length per 24 h for L5 and folding time for L3. An LC₁₀ of spinosad lowered the fold length per 24 h and the number of head swings for L5. An LC₂₅ of spinosad prolonged leaf selection time, and decreased primary fold length, binds per primary fold, binds per fold and fold length per 24 h in L5.

CONCLUSION

Emamectin benzoate and spinosad exerted stronger sublethal effects on the folding and spinning behavior of C. medinalis than chlorpyrifos and chlorantraniliprole. These results provide better understanding of the sublethal effects of interactions of insecticides on C. medinalis. © 2017 Society of Chemical Industry.

Implementation of Fractal Dimension and Self-Organizing Map to Detect Toxic Effects of Toluene on Movement Tracks of Daphnia magna

Movement behaviors of an indicator species, Daphnia magna, in response to contaminants have been implemented to monitor environmental disturbances. Complexity in movement tracks of Daphnia magna was characterized by use of fractal dimension and self-organizing map. The individual movement tracks of D. magna were continuously recorded for 24 hours before and after treatments with toluene at the concentration of 10 mg/L, respectively. The general complexity in movement tracks (10 minutes) was characterized by fractal dimension. Results showed that average fractal dimension of movement tracks was decreased from 1.62 to 1.22 after treatments. The instantaneous movement parameters of movement segments in 5 s were input into the self-organizing map to investigate the swimming pattern changes under stresses of toluene. Abnormal behaviors of D. magna are more frequently observed after treatments than before treatments. Computational methods in ecological informatics could be utilized to obtain the useful information in behavioral data of D. magna and would be further applied as an in situ monitoring tool in water environment.

No evidence of increased growth or mortality in fish exposed to oxazepam in semi-natural ecosystems

An increasing number of short-term laboratory studies on fish reports behavioral effects from exposure to aquatic contaminants or raised carbon dioxide levels affecting the GABA_A receptor. However, how such GABAergic behavioral modifications (GBMs) impact populations in more complex natural systems is not known. In this study, we induced GBMs in European perch (Perca fluviatilis) via exposure to a GABA agonist (oxazepam) and followed the effects on growth and survival over one summer (70days) in replicated pond ecosystems. We hypothesized that anticipated GBMs, expressed as anti-anxiety like behaviors (higher activity and boldness levels), that increase feeding rates in laboratory assays, would; i) increase growth and ii) increase mortality from predation. To test our hypotheses, 480 PIT tagged perch of known individual weights, and 12 predators (northern pike, Esox lucius) were evenly distributed in 12 ponds; six control (no oxazepam) and six spiked (15.5±4μgl^-1 oxazepam [mean±1S.E.]) ponds. Contrary to our hypotheses, even though perch grew on average 16% more when exposed to oxazepam, we found no significant difference between exposed and control fish in growth (exposed: 3.9±1.2g, control: 2.9±1g [mean±1S.E.], respectively) or mortality (exposed: 26.5±1.8individuals pond^-1, control: 24.5±2.6individuals pond^-1, respectively). In addition, we show that reduced prey capture efficiency in exposed pike may explain the lack of significant differences in predation. Hence, our results suggest that GBMs, which in laboratory studies impact fish behavior, and subsequently also feeding rates, do not seem to generate strong effects on growth and predation-risk in more complex and resource limited natural environments.

Unsuitable use of DMSO for assessing behavioral endpoints in aquatic model species

Dimethyl sulfoxide (DMSO) is a universally used aprotic solvent with the ability to permeate biological membranes and thus is commonly used to achieve appropriate biological availability of hydrophobic toxicants. While DMSO as a carrier medium has a reportedly low toxicity and is routinely employed in ecotoxicology, very little is known about its effect on dynamic behavioral parameters. This study presents a comparative analysis of the lethal and behavioral effects of exposures to DMSO concentrations of 0.1-10% on several test species such as: neonates of the freshwater crustacean Daphnia magna, nauplii of the marine crustacean Artemia franciscana, the marine crustacean Allorchestes compressa, embryos and larvae of the freshwater fish Danio rerio. The results demonstrated that DMSO did not cause statistically significant mortality even at concentrations close to 1% but induced clear and significant behavioral abnormalities in response to sublethal concentrations on all test species. These included hypoactivity syndrome in A. franciscana, A. compressa, D. magna and zebrafish larvae while a slight time-dependent hyperactivity response was observed in zebrafish embryos. For the majority of test species, behavioral changes such as moving distance, acceleration and burst movement were often observed during the first hours of exposure. These results indicate that caution should be exercised when using DMSO as a carrier solvent in experiments assessing behavioral endpoints.

Ecotoxicology Goes on a Chip: Embracing Miniaturized Bioanalysis in Aquatic Risk Assessment

Biological and environmental sciences are, more than ever, becoming highly dependent on technological and multidisciplinary approaches that warrant advanced analytical capabilities. Microfluidic lab-on-a-chip technologies are perhaps one the most groundbreaking offshoots of bioengineering, enabling design of an entirely new generation of bioanalytical instrumentation. They represent a unique approach to combine microscale engineering and physics with specific biological questions, providing technological advances that allow for fundamentally new capabilities in the spatiotemporal analysis of molecules, cells, tissues, and even small metazoan organisms. While these miniaturized analytical technologies experience an explosive growth worldwide, with a substantial promise of a direct impact on biosciences, it seems that lab-on-a-chip systems have so far escaped the attention of aquatic ecotoxicologists. In this Critical Review, potential applications of the currently existing and emerging chip-based technologies for aquatic ecotoxicology and water quality monitoring are highlighted. We also offer suggestions on how aquatic ecotoxicology can benefit from adoption of microfluidic lab-on-a-chip devices for accelerated bioanalysis.

Rapid Detection of Sublethal Toxicity Using Locomotor Activity of Rainbow Trout Juveniles

This study examined changes in locomotor activity of the rainbow trout (Oncorhynchus mykiss) juveniles exposed to sublethal concentrations of hexavalent chromium (Cr⁶⁺) (as a single pollutant) and landfill leachate (as an complex mixture of mainly organic compounds, including trace amounts of metals). Fish were first examined for baseline behavior patterns for 3 h to determine the appropriate duration of acclimation and the control level. The average velocity of fish was found to be the most informative among other endpoints throughout the 3 h long acclimation. Under the effect of both test substances, fish locomotor activity significantly increased after 5 min reaching maximum values after 10 min of exposure. The juveniles exposed to leachate were more responsive than those exposed to Cr⁶⁺. However, in this study we did not succeed in identifying pollutants from the elicited fish behavioral response patterns.

Feeding Behavior of an Aquatic Snail as a Simple Endpoint to Assess the Exposure to Cadmium

One of the aims of ecotoxicology is the assessment of the effects of chemicals on the ecosystems. Bioassays assessing lethality are frequently used in ecotoxicology, however they usually employ supra-environmental toxic concentrations. Toxicity tests employing behavioral endpoints may present a balance between simplicity (i.e., laboratory bioassays) and complexity (i.e., relevant ecological effects). The aim of this study was to develop a feeding behavioral bioassay with the aquatic snail, Potamopyrgus antipodarum, which included a 2 days exposure to cadmium, followed by a 9 days post-exposure observational period. Several behavioral feeding endpoints were monitored, including percentage of actively feeding animals, percentage of animals in food quadrants and a mobility index. The percentage of actively feeding animals was reduced by the four cadmium treatments (0.009, 0.026, 0.091 and 0.230 mg Cd/L) with the stronger effect in the highest concentration. The two highest cadmium concentrations significantly reduced the percentage of animals in food quadrants and the mobility index. Therefore, the percentage of actively feeding animals was the most sensitive endpoint to cadmium toxicity as the four cadmium concentrations caused a significant decrease in this endpoint. It is concluded that feeding behavior is a useful endpoint to detect the exposure of aquatic snails to cadmium.

An ecotoxicological view on neurotoxicity assessment

The numbers of potential neurotoxicants in the environment are raising and pose a great risk for humans and the environment. Currently neurotoxicity assessment is mostly performed to predict and prevent harm to human populations. Despite all the efforts invested in the last years in developing novel in vitro or in silico test systems, in vivo tests with rodents are still the only accepted test for neurotoxicity risk assessment in Europe. Despite an increasing number of reports of species showing altered behaviour, neurotoxicity assessment for species in the environment is not required and therefore mostly not performed. Considering the increasing numbers of environmental contaminants with potential neurotoxic potential, eco-neurotoxicity should be also considered in risk assessment. In order to do so novel test systems are needed that can cope with species differences within ecosystems. In the field, online-biomonitoring systems using behavioural information could be used to detect neurotoxic effects and effect-directed analyses could be applied to identify the neurotoxicants causing the effect. Additionally, toxic pressure calculations in combination with mixture modelling could use environmental chemical monitoring data to predict adverse effects and prioritize pollutants for laboratory testing. Cheminformatics based on computational toxicological data from in vitro and in vivo studies could help to identify potential neurotoxicants. An array of in vitro assays covering different modes of action could be applied to screen compounds for neurotoxicity. The selection of in vitro assays could be guided by AOPs relevant for eco-neurotoxicity. In order to be able to perform risk assessment for eco-neurotoxicity, methods need to focus on the most sensitive species in an ecosystem. A test battery using species from different trophic levels might be the best approach. To implement eco-neurotoxicity assessment into European risk assessment, cheminformatics and in vitro screening tests could be used as first approach to identify eco-neurotoxic pollutants. In a second step, a small species test battery could be applied to assess the risks of ecosystems.

A short-term swimming speed alteration test with nauplii of Artemia franciscana

The presence of toxicant needs to be assessed within short time in order to effectively protect the aquatic environment from serious threat. Based on the observation that at high temperatures aquatic organisms become more vulnerable to stressors than those maintained at room temperature, a new test was developed. The proposed bioassay consisted in the evaluation of the swimming speed alteration (SSA) of nauplii of Artemia franciscana incubated at 39°C (± 1) for 6h, using a Swimming Behavior Recorder system (SBR). A comparative ecotoxicological study between the 6h SSA test and the 24h mortality test was carried out in order to validate the new method in terms of sensitivity by means of EC₅₀ values. The bioassay was applied to screen different toxicants: K₂Cr₂O₇, Cu(SO₄)₂, NaClO, SDS and Sertraline hydrochloride. The EC_50s calculated for the short-term SSA test and those of the mortality test showed comparable values. For all toxicants, the 6h SSA test was proved to be as sensitive as the 24h mortality test. The method developed in this study is the first temperature-based toxicity test with nauplii of Artemia franciscana and it represents an attractive assay in ecotoxicology because of its convenience in terms of time and costs, feasibility and sensitivity.

A Millifluidic System for Analysis of Daphnia magna Locomotory Responses to Water-born Toxicants

Aquatic toxicity testing in environmental monitoring and chemical risk assessment is critical to assess water quality for human use as well as predict impact of pollutants on ecosystems. In recent years, studies have increasingly focused on the relevance of sub-lethal effects of environmental contaminants. Sub-lethal toxicity endpoints such as behavioural responses are highly integrative and have distinct benefits for assessing water quality because they occur rapidly and thus can be used to sense the presence of toxicants. Our work describes a Lab-on-a-Chip system for the automated analysis of freshwater cladoceran Daphnia magna locomotory responses to water-born toxicants. The design combines a Lab-on-a-Chip system for Daphnia sp. culture under perfusion with time-resolved videomicroscopy and software tracking locomotory activity of multiple specimens. The application of the system to analyse the swimming behaviour of water fleas exposed to different concentrations of water-born toxicants demonstrated that Lab-on-a-Chip devices can become important research tools for behavioural ecotoxicology and water quality biomonitoring.

A Method for Identifying Pollution Sources of Heavy Metals and PAH for a Risk-Based Management of a Mediterranean Harbour

A procedure for assessing harbour pollution by heavy metals and PAH and the possible sources of contamination is proposed. The procedure is based on a ratio-matching method applied to the results of principal component analysis (PCA), and it allows discrimination between point and nonpoint sources. The approach can be adopted when many sources of pollution can contribute in a very narrow coastal ecosystem, both internal and outside but close to the harbour, and was used to identify the possible point sources of contamination in a Mediterranean Harbour (Port of Vado, Savona, Italy). 235 sediment samples were collected in 81 sampling points during four monitoring campaigns and 28 chemicals were searched for within the collected samples. PCA of total samples allowed the assessment of 8 main possible point sources, while the refining ratio-matching identified 1 sampling point as a possible PAH source, 2 sampling points as Cd point sources, and 3 sampling points as C > 12 point sources. By a map analysis it was possible to assess two internal sources of pollution directly related to terminals activity. The study is the prosecution of a previous work aimed at assessing Savona-Vado Harbour pollution levels and suggested strategies to regulate the harbour activities.

Comparison of social behavior responses of Japanese medaka (Oryzias latipes) to lethal and sublethal chlorpyrifos concentrations at different exposure times

Chlorpyrifos (CPF) is one of the most widely used insecticides and has been found in both urban and rural water bodies. In this study, we studied variations in the social behavioral patterns, swimming behavior, and brain acetylcholinesterase (AChE) activity of Japanese medaka exposed to lethal (0.12mg/L) and sublethal (0.012mg/L) concentrations of CPF after different exposure times. Group behavior performance (schooling, shoaling, and solitary) was determined on day 4 of lethal exposure and on days 4, 8, and 12 of sublethal exposure. Swimming speed and brain AChE activity were measured on days 4, 8, 12, 16, and 20 of sublethal CPF exposure. We observed significant decreases in social behavior and swimming speed (i.e., hypoactivity) in fish exposed to lethal CPF concentrations for 4 days. At the sublethal concentration, there was increased schooling duration and hyperactivity of fish on day 8 but not on day 4. In contrast, 12 days of sublethal CPF exposure resulted in social behavior responses similar to those after 4 days' lethal exposure, i.e., significant decreases in schooling frequency and duration with a notable increase in duration of solitary behavior. Brain AChE activity was inhibited in a time-dependent manner. Altered fish behavior in response to organophosphorus pesticides such as CPF may be mediated by more than AChE inhibition alone.

Acute toxicity of cadmium in Anisops sardeus (Heteroptera:Notonectidae): Effects on adult and nymphal survival and swimming behavior

Adult female and male, and final instar nymph of Anisops sardeus (Heteroptera: Notonectidae) were exposed to graded concentrations of cadmium in 96h static-with-renewal acute toxicity tests, which were conducted in dry (March) and wet (May-June) seasons. The 96h LC₅₀ values for instar V nymph, adult female and male were found to be 0.9, 0.59 and 0.51mgL^-1 Cd, respectively, in wet season, while these were 26.7 and 20.2mgL^-1 Cd for adult female and male, respectively, in dry season. Adult males were most sensitive to Cd, followed by females in both seasons, while highest tolerance in wet season was observed in instar V nymph. There was a steep decline in LC₅₀ values from 24 to 96h in wet season. Besides mortality at higher concentrations of Cd, sublethal effects in terms of reduced 'velocity magnitude' (swimming speed) and mostly increased 'rotation angle' (turning angle) could be discerned at concentrations as low as 0.03mgL^-1. The swimming pattern of Cd-exposed nymph and adults were also affected. Based on the bioaccumulation factor (BAF) values, A. sardeus could be designated as a macroconcentrator of Cd (BAF > 2), with highest Cd accumulation in instar V nymph, followed by that in female, and with lowest Cd accumulation in male.

Biochemical approaches to assess oxidative stress induced by exposure to natural and synthetic dyes in early life stages in zebrafish

Zebrafish early life stages were found to be sensitive to several synthetic dyes widely used in industries. However, as environmental concentrations of such contaminants are often at sublethal levels, more sensitive methods are required to determine early-warning adverse consequences. The aim of this study was to utilize a multibiomarker approach to examine underlying oxidative stress mechanisms triggered by sublethal concentrations of synthetic azo dye Basic Red 51 (BR51), the natural dye erythrostominone (ERY), and its light-degraded product using zebrafish embryos. Biochemical biomarkers included parameters of detoxification and markers of antioxidant system, as well as oxidative damage. Results showed pro-oxidant mechanisms attributed to BR51 and ERY as evidenced by increased glutathione S-transferase (GST) activity, a phase II detoxification enzyme related to reactive oxygen species detoxification. BR51 also elevated total glutathione (GSH+GSSG) levels and catalase activity. However, both dyes induced oxidative damage as evidenced by elevated lipid peroxidation content. In contrast, when the natural dye was photodegraded, no marked effects were observed for all biomarkers assessed. Data indicate that such dyes are pro-oxidants at sublethal concentrations, predominantly involving GSH and/or related enzymes pathway.

Adverse effects of the SSRI antidepressant sertraline on early life stages of marine invertebrates

Widespread contamination of coastal environments by emerging compounds includes low concentrations of pharmaceuticals. These pollutants are not currently incorporated in monitoring programs despite their effects on non-target organisms are very little documented. Among the selective serotonin reuptake inhibitor (SSRI) antidepressants, sertraline (SRT) is one of the most prescribed globally. In this work, earlier life stages of Amphibalanus amphitrite, Brachionus plicatilis and Mytilus galloprovincialis were exposed to environmental concentrations of SRT in order to study both sub-lethal and lethal responses in 24/48 h-tests. Low concentrations of SRT altered significantly swimming behavior in A. amphitrite and B. plicatilis giving 48 h-EC₅₀ (μg/L) of 113.88 and 282.23, respectively whereas higher values were observed for mortality and immobilization. EC₅₀ embryotoxicity with M. galloprovincialis was 206.80 μg/L. This work add new data about SRT ecotoxicity on marine invertebrates and confirms the applicability of behavioral endpoints to evaluate the environmental impact of antidepressants in marine organisms.

Old model organisms and new behavioral end-points: Swimming alteration as an ecotoxicological response

Behavioral responses of aquatic organisms have received much less attention than developmental or reproductive ones due to the scarce presence of user-friendly tools for their acquisition. The technological development of data acquisition systems for quantifying behavior in the aquatic environment and the increase of studies on the understanding the relationship between the behavior of aquatic organisms and the physiological/ecological activities have generated renewed interest in using behavioral responses also in marine ecotoxicology. Recent reviews on freshwater environment show that behavioral end-points are comparatively fast and sensitive, and warrant further attention as tools for assessing the toxicological effects of environmental contaminants. In this mini-review, we perform a systematic analysis of the most recent works that have used marine invertebrate swimming alteration as behavioral end-point in ecotoxicological studies by assessing the differences between behavioral and acute responses in a wide range of species, in order to compare their sensitivity.

Orientation behavior is a good biomarker of trace metal contamination in Parallelomorphus laevigatus (Coleoptera, Carabidae)

Behavioral ecotoxicology has become very important in the short time since a change in behavior is very often the first response to environmental altered conditions. We investigated the influence of trace metal intake on the spatial orientation performances of the carabid beetle Parallelomorphus laevigatus, fundamental ability for its survival. The aim of this study was to consider the solar orientation as behavioral biomarker for exposure to trace metal contamination. Therefore, we tested the ability of solar orientation of specimens of this species, fed with shrimps contaminated with three different concentrations of Cu, Zn, or Hg. We carried out the orientation tests after 1, 3, 7, and 10 days of contaminated feeding. Subsequently, we fed these beetles with not contaminated shrimps and again tested them after 1, 3, 7, and 10 days. For all three metals considered and, regardless of the degree of contamination of the food, we have found a progressive and significant counterclockwise displacement of the angle of orientation and a corresponding progressive reduction in the precision in the directional choices by the animals. We also noticed a clear growing recovery in the normal orientation by these insects after returning to their feeding with uncontaminated food. In conclusion, we can consider the orientation in space of P. laevigatus as a behavioral biomarker for exposure to trace metal contamination. We believe that the intake of trace metals may induce the insects to make mistakes in their spatial orientation, due to an acceleration of their biological clock. Such a clock malfunction is not definitive, since the return to a normal diet restores P. laevigatus the ability to re-make the correct directional choices. Ultimately, our results confirm the usefulness of behavioral ecotoxicology investigations; moreover, they stimulate the opportunity to deepen the understanding of functioning of the biological clock in the animals.

Evaluation of the sensitivity spectrum of a video tracking system with zebrafish (Danio rerio) exposed to five different toxicants

The aim of this study was to develop a biological early warning system for the detection of aquatic toxicity and test it with five toxicants with distinct chemical nature. This was done in order to verify the spectrum of sensitivities of the proposed system, as well as the potential identification capability of the tested contaminants, using only the analysis of zebrafish's behavior. Six experimental conditions were tested: negative control and five toxicants (bleach, lindane, tributyltin, mercury, and formaldehyde). The exposure time was 45 min, and the concentrations used corresponded to 9% of LC₅₀'s-96 h for the tested compounds, to ensure ecologically relevant results. A total of 108 fish were used, with each individual experimental condition being tested 18 times. A statistical model of diagnosis was used, combining self-organizing map and correspondence analysis. The values of sensitivity, specificity, accuracy, false positive, false negative, positive predictive value (PPV), and negative predictive value (NPV) were calculated. The objectives of the work were accomplished and the system showed a good overall diagnostic performance with 79% in accuracy, 77% in sensitivity, and 88% in specificity. The lowest result of the predictive values was 78% (lindane and mercury), in the case of the NPV, and 86% (bleach and lindane), in the case of the PPV. The best result of the predictive values was 100% (bleach and tributyltin), for the NPV, and 89% (tributyltin), for the PPV. Regarding the five tested toxicants, the system was able to correctly identify the agent responsible for the contamination in 40% of the positive diagnoses.

Ecotoxicological assessment of the impact of fluoride (F-) and turbidity on the freshwater snail Physella acuta in a polluted river receiving an industrial effluent

We carried out field studies and laboratory experiments to assess the impact of fluoride (F^-) and turbidity on the freshwater snail Physella acuta in a polluted river receiving an industrial effluent (the middle Duraton River, Central Spain). Fluoride concentrations and turbidity levels significantly increased downstream from the industrial effluent (with the highest values being 0.6 mg F^-/L and 55.2 nephelometric turbidity unit). In addition, higher deposition of fine inorganic matter was evident at polluted sampling sites. Conversely, the abundance of P. acuta significantly declined (until its virtual disappearance) downstream from the industrial effluent. Toxicity bioassays showed that P. acuta is a relatively tolerant invertebrate species to fluoride toxicity, with estimated safe concentrations (expressed as LC_0.10 values for infinite hours of exposure) for juvenile and adult snails being 2.4 and 3.7 mg F^-/L, respectively. Furthermore, juvenile snails (more sensitive than adult snails) did not show significant alterations in their behavior through 15 days of exposure to 2.6 mg F^-/L: mean values of the proportion of test snails located on the water surface habitat, as well as mean values of the sliding movement rate (velocity) of test snails, never showed significant differences when comparing control and treatment glass vessels. It is concluded that instream habitat degradation, derived from increased turbidity levels, might be a major cause for significant reductions in the abundance of P. acuta downstream from the industrial effluent. The presence of the competing gastropod Ancylus fluviatilis could also affect negatively the recovery of P. acuta abundance.

Feeding Preference and Sub-chronic Effects of ZnO Nanomaterials in Honey Bees (Apis mellifera carnica)

The extensive production of zinc oxide (ZnO) nanomaterials (NMs) may result in high environmental zinc burdens. Honeybees need to have special concern due to their crucial role in pollination. Our previous study indicated that low concentrations of ZnO NMs, corresponding to 0.8 mg Zn/mL, have a neurotoxic potential for honeybees after a 10-day oral exposure. Present study was designed to investigate the effect of a short, dietary exposure of honeybees to ZnO NMs at concentrations 0.8-8 mg Zn/mL on consumption rate, food preference, and two enzymatic biomarkers-a stress-related glutathione S-transferase (GST) and the neurotoxicity biomarker acetylcholinesterase (AChE). Consumption rate showed a tendency toward a decrease feeding with the increasing concentrations of ZnO NMs. None of Zn NMs concentrations caused alterations in mortality rate and in the activities of brain GST and AChE. To investigate if there is an avoidance response against Zn presence in food, 24-h two-choice tests were performed with control sucrose diet versus sucrose suspensions with different concentrations of ZnO NMs added. We demonstrated that honeybees prefer ZnO NMs ZnO NMs containing suspensions, even at highest Zn concentrations tested, compared with the control diet. This indicates that they might be able to perceive the presence of ZnO NMs in sucrose solution. Because honeybees feed frequently the preference towards ZnO NMs might have a high impact on their survival when exposed to these NMs.

Integrative behavioral ecotoxicology: bringing together fields to establish new insight to behavioral ecology, toxicology, and conservation

The fields of behavioral ecology, conservation science, and environmental toxicology individually aim to protect and manage the conservation of wildlife in response to anthropogenic stressors, including widespread anthropogenic pollution. Although great emphasis in the field of toxicology has been placed on understanding how single pollutants affect survival, a comprehensive, interdisciplinary approach that includes behavioral ecology is essential to address how anthropogenic compounds are a risk for the survival of species and populations in an increasingly polluted world. We provide an integrative framework for behavioral ecotoxicology using Tinbergen’s four postulates (causation and mechanism, development and ontogeny, function and fitness, and evolutionary history and phylogenetic patterns). The aims of this review are: 1) to promote an integrative view and re-define the field of integrative behavioral ecotoxicology; 2) to demonstrate how studying ecotoxicology can promote behavior research; and 3) to identify areas of behavioral ecotoxicology that require further attention to promote the integration and growth of the field.

The consequences of sublethal exposure to insecticide on the survivorship and mobility of Halyomorpha halys (Hemiptera: Pentatomidae)

BACKGROUND

The direct lethal effects of conventional and organic insecticides have been investigated thoroughly for all life stages of Halyomorpha halys. However, the sublethal effects of insecticides on the behavior of H. halys have not been well documented. Our aims were to evaluate the impact of a brief 5 min exposure to residues of bifenthrin, dinotefuran, methomyl, thiamethoxam and thiamethoxam + λ-cyhalothrin on survivorship, horizontal and vertical movement, and flight capacity of adult H. halys under laboratory conditions.

RESULTS

Over half of the insecticide-exposed adults were classified as affected, moribund or dead after the 5 min exposure, compared with only 6% of the adults in the water-only control. We found that the horizontal movement, vertical climbing and flight capacity of adults exposed to insecticides were decreased by 20-60% overall relative to the water-only control. The most lethal insecticide was bifenthrin.

CONCLUSION

Many insecticide-exposed H. halys adults retained significant mobility and flight capacity, with flight most pronounced immediately after exposure. These results suggest that brief exposure periods to efficacious insecticides will result in high dispersal and low mortality. Therefore, management strategies that enhance the retention of H. halys on insecticide-coated surfaces should be considered to ensure that adults are exposed to a lethal dose of insecticide. © 2016 Society of Chemical Industry.

Environmental relevant levels of a benzodiazepine (oxazepam) alters important behavioral traits in a common planktivorous fish, (Rutilus rutilus)

Environmental pollution by pharmaceuticals is increasingly recognized as a major threat to aquatic ecosystems worldwide. A complex mix of pharmaceuticals enters waterways via treated wastewater effluent and many remain biochemically active after the drugs reach aquatic systems. However, to date little is known regarding the ecological effects that might arise following pharmaceutical contamination of aquatic environments. One group of particular concern is behaviorally modifying pharmaceuticals as seemingly minor changes in behavior may initiate marked ecological consequences. The aim of this study was to examine the influence of a benzodiazepine anxiolytic drug (oxazepam) on key behavioral traits in wild roach (Rutilus rutilus) at concentrations similar to those encountered in effluent surface waters. Roach exposed to water with high concentrations of oxazepam (280 µg/L) exhibited increased boldness, while roach at low treatment (0.84 µg/L) became bolder and more active compared to control fish. Our results reinforce the notion that anxiolytic drugs may be affecting fish behavior in natural systems, emphasizing the need for further research on ecological impacts of pharmaceuticals in aquatic systems and development of new tools to incorporate ecologically relevant behavioral endpoints into ecotoxicological risk assessment.

Exposure to SSRI-type antidepressants increases righting time in the marine snail Ilyanassa obsoleta

Exposure to human antidepressants has been shown to disrupt locomotion and other foot-mediated mechanisms in aquatic snails. We tested the effect of three selective serotonin reuptake inhibitor (SSRI)- and one selective serotonin-norepinephrine reuptake inhibitor (SNRI)-type antidepressants on the righting response in the marine snail, Ilyanassa obsoleta. All four antidepressants (fluoxetine, sertraline, paroxetine, venlafaxine) significantly increased righting time compared with controls with an exposure time as short as 1 h. Dose responses were nonmonotonic with effects seen mainly at the lowest exposure concentrations and shortest duration. The lowest concentration to show an effect was 3.45 μg/L fluoxetine with a 2-h exposure period and is about 3.71 times higher than environmental concentrations. Our results highlight rapid disruption of another foot-mediated behavior in aquatic snails by SSRI-type antidepressants. We discuss these and other reported nonmonotonic dose responses caused by antidepressants in terms of the various possible physiological mechanisms of action in nontarget aquatic species.

Does selective logging stress tropical forest invertebrates? Using fat stores to examine sublethal responses in dung beetles

The increased global demand for tropical timber has driven vast expanses of tropical forests to be selectively logged worldwide. While logging impacts on wildlife are predicted to change species distribution and abundance, the underlying physiological responses are poorly understood. Although there is a growing consensus that selective logging impacts on natural populations start with individual stress-induced sublethal responses, this literature is dominated by investigations conducted with vertebrates from temperate zones. Moreover, the sublethal effects of human-induced forest disturbance on tropical invertebrates have never been examined. To help address this knowledge gap, we examined the body fat content and relative abundance of three dung beetle species (Coleoptera: Scarabaeinae) with minimum abundance of 40 individuals within each examined treatment level. These were sampled across 34 plots in a before-after control-impact design (BACI) in a timber concession area of the Brazilian Amazon. For the first time, we present evidence of logging-induced physiological stress responses in tropical invertebrates. Selective logging increased the individual levels of fat storage and reduced the relative abundance of two dung beetle species. Given this qualitative similarity, we support the measurement of body fat content as reliable biomarker to assess stress-induced sublethal effects on dung beetles. Understanding how environmental modification impacts the wildlife has never been more important. Our novel approach provides new insights into the mechanisms through which forest disturbances impose population-level impacts on tropical invertebrates.

Development of a Low-Cost Ecotoxicological Bioassay Based on the Feeding Behaviour of the Aquatic Snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca)

Conventional acute tests are not suited to assess the effects of toxicants, because they do not use the concentrations that are usually found in natural ecosystems. By contrast, nonlethal realistic concentrations may cause deleterious effects on animal fitness as a consequence of behaviour impairment. Behaviour is a good integrative variable of complex biochemical and physiological processes. Therefore, bioassays based on behaviour are a useful tool in ecotoxicology. In this study, two bioassays were conducted: (1) acute bioassay (48 h) of acetone on the aquatic snail Potamopyrgus antipodarum, and (2) video-recording behavioural bioassay with pulse exposures to acetone to assess its effects on feeding behaviour. In the latter, animals were exposed to three pulses of acetone (24 h each) with 6 days of postexposure after each pulse. This design allowed us to assess the degree of feeding behaviour recovery after exposure and the effects of repeated pulses. Our results show that postexposure periods have an important effect on the recovery of normal feeding behaviour and that this developed bioassay is an ecotoxicological tool with a relatively low-cost and a short-time consuming. The application of this new tool to different ecotoxicological requirements is discussed.

Behavioral responses of juvenile Daphnia magna after exposure to glyphosate and glyphosate-copper complexes

Glyphosate (N-(phosphonomethyl)glycine) is the active ingredient in a range of popular broad-spectrum herbicide formulations. Glyphosate is a chelating agent that can form stable complexes with divalent metal ions including Cu(II). Little is known about the bioavailability and ecotoxicity of glyphosate-Cu(II) complexes to aquatic organisms. In this study, we used video tracking and behavior analysis to investigate sublethal effects of binary mixtures of glyphosate and Cu(II) to juvenile D. magna. Behavioral responses were quantified for individual D. magna after 24h and 48h exposure to glyphosate and glyhosate-Cu(II) mixtures. Sublethal concentrations resulted in decreases in swimming velocity, acceleration speed, and distance moved whereas inactive time of D. magna increased. Distance moved and inactive time were the most responsive parameters to glyphosate and glyphosate-Cu(II) exposure. On a molar basis, glyphosate-Cu(II) complexes appeared more toxic to D. magna than glyphosate alone. The 48h EC50 for glyphosate and glyphosate-Cu(II) determined from swimming distance were 75.2μM and 8.4μM, respectively. In comparison, traditional visual observation of mobility resulted in 48h EC50 values of 52.8μM and 25.5μM for glyphosate and glyphosate-Cu(II), respectively. The behavioral responses indicated that exposure of D. magna to mixtures of glyphosate and Cu(II) attenuated acute metal toxicity but increased apparent glyphosate toxicity due to complexation with Cu(II). The study suggests that glyphosate is a likely mediator of aquatic metal toxicity, and that video tracking provides an opportunity for quantitative studies of sublethal effects of pesticide complexes.

Resilience assessment of a biological early warning system based on the locomotor behavior of zebrafish (Danio rerio)

With the development of new tools such as biological early warning systems, it becomes extremely important to test their reliability and detection capability. This work aimed at testing the sturdiness of a video tracking system by determining whether the detection capability does not deteriorate over time, after successive exposures of the zebrafish to three different toxicants, namely sodium hypochlorite, bisphenol A, and ethanol. Zebrafish were exposed to the three tested compounds separately (one fish, one toxicant) once a day, for 1 h and 30 m over 9 days, to 9 % of the 96 h LC50 of the respective toxicant. The behavior analysis was based on nine movement descriptor parameters of the fish, namely: angular velocity; linear velocity; spatial dispersion; linear acceleration; and angular acceleration. A statistical method was developed using self-organizing map (SOM), correspondence analysis, and linear and orthogonal multiple regression models. The results indicated that the system was able to successfully detect the three toxicants. With ethanol, the detection capability was maintained, but in the case of the sodium hypochlorite and bisphenol A, a deterioration of the detection capability occurred over the 9 days. This effect may be due to the induction of detoxification mechanisms and physiological acclimation, or due to the accumulation of adverse effects caused by the repeated exposure to the toxicants. Future works, especially those focusing on the application of similar early warning systems in real-world scenarios, should regularly exchange the sentinel organisms, to avoid degradation of the detection capability, as verified with two of the three tested compounds.

Active and passive spatial avoidance by aquatic organisms from environmental stressors: A complementary perspective and a critical review

Spatial avoidance is a mechanism by which many organisms prevent their exposure to environmental stressors, namely chemical contaminants. Numerous studies on active avoidance and drift by aquatic organisms, as well as the main approaches used to measure both responses, were reviewed. We put forward a particular recommendation regarding methodological approaches: active avoidance should preferably be evaluated under a dilution gradient in a multi-compartmented system instead of in a bi-compartmented system. Available data on spatial avoidance from contamination indicate that emigration can occur at even lower contaminant concentrations than sub-individual noxious effects (assessed with the traditional forced-exposure assays), challenging the widely accepted paradigm in ecotoxicology that contaminant-driven adverse consequences at the population level result from a time delayed cascade of sequentially linked biochemical, cellular, physiological, and finally whole organism deleterious effects. Therefore, contaminants should not be viewed solely as potential toxicants at the individual level, but also as potential disturbers of habitats, by making the latter, at least partially, unsuited to accommodate life. Also, exposure to contamination is needed to trigger avoidance, but uptake is not mandatory, which demands the concept of exposure to be expanded, to include also the mere perception of the stressor. Since emigration eventually leads to local population extinction, and thus to severe implications for ecosystem structure and functioning, we then recommend that avoidance data be incorporated in environmental risk assessment schemes.

Swimming speed alteration in the early developmental stages of Paracentrotus lividus sea urchin as ecotoxicological endpoint

Behavioral endpoints have been used for decades to assess chemical impacts at concentrations unlikely to cause mortality. With recently developed techniques, it is possible to investigate the swimming behavior of several organisms under laboratory conditions. The aims of this study were: i) assessing for the first time the feasibility of swimming speed analysis of the early developmental stage sea urchin Paracentrotus lividus by an automatic recording system ii) investigating any Swimming Speed Alteration (SSA) on P. lividus early stages exposed to a chemical reference; iii) identifying the most suitable stage for SSA test. Results show that the swimming speed of all the developmental stages was easily recorded. The swimming speed was inhibited as a function of toxicant concentration. Pluteus were the most appropriate stage for evaluating SSA in P. lividus as ecotoxicological endpoint. Finally, swimming of sea urchin early stages represents a sensitive endpoint to be considered in ecotoxicological investigations.

Pigeons home faster through polluted air

Air pollution, especially haze pollution, is creating health issues for both humans and other animals. However, remarkably little is known about how animals behaviourally respond to air pollution. We used multiple linear regression to analyse 415 pigeon races in the North China Plain, an area with considerable air pollution, and found that while the proportion of pigeons successfully homed was not influenced by air pollution, pigeons homed faster when the air was especially polluted. Our results may be explained by an enhanced homing motivation and possibly an enriched olfactory environment that facilitates homing. Our study provides a unique example of animals’ response to haze pollution; future studies are needed to identify proposed mechanisms underlying this effect.

Upscaling behavioural studies to the field using acoustic telemetry

Laboratory-based behavioural assays are often used in ecotoxicological studies to assess the environmental risk of aquatic contaminants. While results from such laboratory-based risk assessments may be difficult to extrapolate to natural environments, technological advancements over the past decade now make it possible to perform risk assessments through detailed studies of exposed individuals in natural settings. Acoustic telemetry is a technology to monitor movement and behaviour of aquatic organism in oceans, lakes, and rivers. The technology allows for tracking of multiple individuals simultaneously with very high temporal and spatial resolution, with the option to incorporate sensors to measure various physiological and environmental parameters. Although frequently used in fisheries research, aquatic ecotoxicology has been slow to adopt acoustic telemetry as a tool in field-based studies. This mini-review intends to introduce acoustic telemetry to aquatic ecotoxicologists, focusing on the potential of the technology to bridge the gap between laboratory assays and natural behaviours when making toxicological risk assessments.