Arena Size Research Articles

Population dynamics in spatial suppression gene drive models and the effect of resistance, density dependence, and life history.

Due to their super-Mendelian inheritance, gene drive systems have the potential to provide revolutionary solutions to critical public health and environmental problems. For suppression drives, however, spatial structure can cause "chasing" population dynamics that may postpone target population elimination or even cause the drive to fail. In chasing, wild-type individuals elude the drive and recolonize previously suppressed areas. The drive can re-enter these recolonized areas, but often is not able to catch up to wild-type and finally eliminate it. Previous methods for chasing detection are only suitable to limited parameter ranges. In this study with expanded parameter ranges, we found that the shift from chasing dynamics to static equilibrium outcomes is continuous as drive performance is reduced. To quantify this, we defined a Weighted Average Nearest Neighbor statistic to assess the clustering degree during chasing, while also characterizing chasing by the per-generation chance of population elimination and drive loss. To detect chasing dynamics in local areas and to detect the start of chasing, we implemented Density-Based Spatial Clustering of Applications with Noise. Using these techniques, we determined the effect of arena size, resistance allele formation rate in both the germline and in the early embryo from maternally deposited Cas9, life history and reproduction strategies, and density-dependent growth curve shape on chasing outcomes. We found that larger real-world areas will be much more vulnerable to chasing and that species with overlapping generations, fecundity-based density dependence, and concave density-dependent growth curves have smaller and more clustered local chasing with a greater chance of eventual population elimination. We also found that embryo resistance and germline resistance hinder drive performance in different ways. These considerations will be important for determining the necessary drive performance parameters needed for success in different species, and whether future drives could potentially be considered as release candidates.

Effects of 4 Testing Arena Sizes and 11 Types of Embryo Media on Sensorimotor Behaviors in Wild-Type and chd7 Mutant Zebrafish Larvae.

The larval zebrafish is a highly versatile model across research disciplines, and the expanding use of behavioral analysis has contributed to many advances in neuropsychiatric, developmental, and toxicological studies, often through large-scale chemical and genetic screens. In the absence of standardized approaches to larval zebrafish behavior analysis, however, it is critical to understand the impact on behavior of experimental variables such as the size of testing arenas and the choice of embryo medium. Using a custom-built, modular high-throughput testing system, we examined the effects of 4 testing arena sizes and 11 types of embryo media on conserved sensorimotor behaviors in zebrafish larvae. Our data show that testing arena size impacts acoustic startle sensitivity and kinematics, as well as spontaneous locomotion and thigmotaxis, with fish tested in larger arenas displaying reduced startle sensitivity and increased locomotion. We also find that embryo media can dramatically affect startle sensitivity, kinematics, habituation, and prepulse inhibition, as well as spontaneous swimming, turning, and overall activity. Common medium components such as methylene blue and high calcium concentration consistently reduced startle sensitivity and locomotion. To further address how the choice of embryo medium can impact phenotype expression in zebrafish models of disease, we reared chd7 mutant larvae, a model of CHARGE syndrome with previously characterized morphological and behavioral phenotypes, in five different types of media and observed impacts on all phenotypes. By defining the effects of these key extrinsic factors on larval zebrafish behavior, these data can help researchers select the most appropriate conditions for their specific research questions, particularly for genetic and chemical screens.

Population density affects sexual selection in an insect model

Abstract Understanding the impact of demographic and ecological factors on the strength of sexual selection is pivotal to predict eco‐evolutionary dynamics in populations facing environmental change. Density is expected to show pervasive intra‐ and interspecific variation in natural populations, but its effect on sexual selection remains largely unexplored. We tested experimentally the effect of density on standardized metrics of sexual selection in male and female red flour beetles. Specifically, we explored density effects during mating by manipulating the size of mating groups and the mating arena. We found that higher densities imposed by a larger group size amplified the opportunity for pre‐copulatory sexual selection in females and, to a smaller extent, also in males. Moreover, in males, we detected a higher opportunity for post‐copulatory sexual selection in larger groups. By contrast, higher densities imposed by differences in the size of the mating arena resulted in a steeper male sexual selection gradient. Overall, these data suggest that density is an important environmental factor contributing to the tremendous variation in the strength of sexual selection within and among species. Read the free Plain Language Summary for this article on the Journal blog.

Exploratory and Locomotor Activity in Mice Following Selective Lesions of the Hippocampus: Effects of Lesion Site and Open Field Arena Size

Exploratory and Locomotor Activity in Mice Following Selective Lesions of the Hippocampus: Effects of Lesion Site and Open Field Arena Size

Experimental arena size alters larval zebrafish photolocomotor behaviors and influences bioactivity responses to a model neurostimulant

Zebrafish behavior is increasingly common in biomedical and environmental studies of chemical bioactivity. Multiple experimental arena sizes have been used to measure photolocomotion in zebrafish depending on age, endpoints observed, and instrumentation, among other factors. However, the extent to which methodological parameters may influence naïve behavioral performance and detection of behavioral changes is poorly understood. Here we measured photolocomotion and behavioral profiles of naïve larval zebrafish across arena sizes. We then performed concentration response studies with the model neurostimulant caffeine, again across various arena dimensions. We found total swimming distance of unexposed fish to increase logarithmically with arena size, which as related to circumference, area, and volume. Photomotor response during light/dark transitions also increased with arena size. Following caffeine exposure, total distance travelled was significantly (p < 0.001) affected by well size, caffeine treatment (p < 0.001), and the interaction of these two experimental factors (p < 0.001). In addition, behavioral response profiles showed differences between 96 well plates and larger well sizes. Biphasic response, with stimulation at lower concentrations and refraction at the highest concentration, was observed in dark conditions for the 96 well size only, though almost no effects were identified in the light. However, swimming behavior was significantly (p < 0.1) altered in the highest studied caffeine treatment level in larger well sizes during both light and dark periods. Our results indicate zebrafish swim more in larger arenas and arena size influences behavioral response profiles to caffeine, though differences were mostly observed between very small and large arenas. Further, careful consideration should be given when choosing arena size, because small wells may lead to restriction, while larger wells may differentially reflect biologically relevant effects. These findings can improve comparability among experimental designs and demonstrates the importance of understanding confounding methodological variables.

Experimental arena settings might lead to misinterpretation of movement properties.

Movement is an important animal behavior contributing to reproduction and survival. Animal movement is often examined in arenas or enclosures under laboratory conditions. We used the red flour beetle (Tribolium castaneum) to examine here the effect of the arena size, shape, number of barriers, access to the arena's center, and illumination on six movement properties. We demonstrate great differences among arenas. For example, the beetles moved over longer distances in clear arenas than in obstructed ones. Movement along the arena's perimeter was greater in smaller arenas than in larger ones. Movement was more directional in round arenas than in rectangular ones. In general, the beetles stopped moving closer to the perimeter and closer to corners (in the square and rectangular arenas) than expected by chance. In some cases, the arena properties interacted with the beetle sex to affect several movement properties. All these suggest that arena properties might also interact with experimental manipulations to affect the outcome of studies and lead to results specific to the arena used. In other words, instead of examining animal movement, we in fact examine the animal interaction with the arena structure. Caution is therefore advised in interpreting the results of studies on movement in arenas under laboratory conditions and we recommend paying attention also to barriers or obstacles in field experiments. For instance, movement along the arena's perimeter is often interpreted as centrophobism or thigmotaxis but the results here show that such movement is arena dependent.

Environmental conditions of recognition memory testing induce neurovascular changes in the hippocampus in a sex-specific manner in mice

Experiences are linked to emotions impacting memory consolidation and associated brain neuronal circuits. Posttraumatic stress disorder is an example of strong negative emotions affecting memory processes by flashbacks of past traumas. Stress-related memory deficits are also observed in major depressive disorder (MDD). We recently highlighted that sex-specific blood-brain barrier (BBB) alterations underlie stress responses in mice and human depression. However, little is known about the relationship between emotional valence, memory encoding and BBB gene expression. Here, we investigated the effects of novel object recognition (NOR) test, an experience considered of neutral emotional valence, on BBB properties in dorsal vs ventral hippocampus (HIPP) in the context of various environmental conditions (arena size, handling, age). The HIPP is a brain area central for learning and memory processes with the dorsal and ventral subregions being associated with working memory vs reference memory retrieval, respectively. Expression of genes related to BBB integrity are altered in line with learning and memory processes in a region- and sex-specific manner. We observed correlations between poor learning, anxiety, stress-induced corticosterone release and changes in BBB-associated gene expression. Comparison of BBB transcriptomes between sexes also revealed profound differences at baseline in both ventral and dorsal HIPP. Finally, we identified circulating vascular biomarkers, such as sE-selectin and matrix metallopeptidase 9 (MMP-9), altered following NOR exposure supporting that recognition memory formation has an impact on the neurovasculature. Although deemed as a neutral valence test, NOR experimental conditions can shift it toward a negative valence, impacting performance and highlighting the need to minimize anxiety when performing this commonly used test in mice.

Predation in Many Dimensions: Spatial Context Is Important for Meaningful Functional Response Experiments

For simplicity and to minimize variation, functional response experiments frequently use environments of simple physical structure and small size. Less attention is paid to similarity of the experimental environment to the natural environment where predation occurs. Assumptions about predator and prey use of space are often implied in the choice of experimental environment. We illustrate how these assumptions may affect conclusions with an experiment testing how arena size affects a functional response.Toxorhynchites rutiluspreyed upon larvalCulex restuansin containers differing in volume by 15x, but spanning a similar range of prey/liter. The most plausible Type II model included attack rates that were statistically indistinguishable, but in the larger volume, had handling time that was lower by &amp;gt; 30x compared to the smaller volume, suggesting a major change in predator behavior with container volume. When we altered our assumption that predation scales with prey/liter, assuming instead that aggregation causes predation to scale with prey/area of surface or bottom, the conclusions changed: neither attack rate nor handling time differed with container size. Thus, our assumption about how predator and prey used space altered the conclusions of the experiment. We then summarize recently published experiments showing that spatial context affects estimated functional responses. We suggest that functional response experiments would be improved by using larger experimental spaces that represent physical complexity of environments where predation occurs. Greater spatial extent and complexity are likely to cause aggregation of predation. Effects of more realistic spatial context are likely to yield more complete understanding of quantitative aspects of predation.

Long-Range But Not Short-Range Attraction of Male Aedes aegypti (Diptera: Culicidae) Mosquitoes to Humans.

Female Aedes aegypti (Linnaeus) mosquitoes integrate multiple sensory cues to locate human hosts for blood meals. Although male Ae. aegypti swarm around and land on humans in nature to mate, direct evidence of attraction to humans is limited. Male mosquito attraction to human host cues is often undetectable in confined laboratory assays, leading to a misconception that male mosquitoes are not attracted to humans. We used semifield experiments to demonstrate robust attraction of male Ae. aegypti to humans. Human-baited traps captured up to 25% of released males within 15 min, whereas control traps without humans as bait failed to capture males. Rapid attraction to humans was further demonstrated through videography. Males swarmed around and landed on human subjects, with no activity recorded in paired unbaited controls. Finally, we confirm the lack of discernible male attraction to humans in small laboratory cages. Our experiments demonstrate that both male and female Ae. aegypti show attraction to humans, but with clear sex-specific behavioral differences at short-range. Male mosquito attraction to humans is likely to be important for mating success in wild populations and its basis should be further explored. Our results highlight the importance of arena size and assay design for mosquito behavioral research. A better understanding of host cues that attract males could help us to improve mosquito surveillance and control.

How diving flies navigate in for the kill

Snatching their next meal often requires insects to attack upwards, as their prey is more easily visible towards a clear sky background. But this is not the case for killer flies (Coenosia attenuata), which take the risk of performing swift aerial dives to grab their prey from above. Intrigued by this behaviour, Paloma Gonzalez-Bellido from the University of Minnesota, USA, with Sergio Rossoni from the University of Cambridge, UK, and collaborators from Cambridge and the University of Lincoln, UK, set off to understand how these dives compare with upwards or sideways attacks more commonly found in insects in the wild to learn about the flies’ unorthodox hunting strategy.The team released pairs of killer flies in a transparent rectangular arena, dangled a moving black bead in front of them to give them a target to attack, and filmed their hunting manoeuvres in 3D using high-speed cameras. The researchers then used the recordings to extract the flies’ velocity and acceleration during each dive and found that the flies that were taking off from the ceiling reached significantly higher accelerations than those taking off from the walls or the floor of the arena. The dive accelerations were also higher than those measured in free-falling unconscious killer flies, suggesting that they work together with gravity to propel themselves downwards even faster. The researchers also found that the aeronauts could use the angle of their line of sight – the imaginary line between the fly and its prey – to time their take-off to target and influence their dive angle.Aiming to understand how these flight characteristics affect the flies’ hunting strategy, the researchers looked into the factors that determine how the killers navigate in for a kill. Do the flies head directly toward their target, or do the killers observe how their meal changes direction to predict where their victim is going to arrive and aim to intercept it at some point in the future? The researchers converted these strategies into mathematical models, used the data for the position and velocity of real flies and the position of the bead target, and simulated potential flight paths that could have resulted from each strategy. They then compared those paths with the real-life trajectories of the killers and were able to show that the second strategy, where the attackers aim to intercept their quarry at some point in the future, best predicted the killer flies’ paths, no matter where they took off from. However, they also noted that the flies that took off from the ceiling and further ahead of their target were particularly vulnerable to missing their meal. The researchers then adapted their model of the flies’ navigation strategy to include the acceleration needed for the killers to turn a corner and attempt a follow-up attack – a measure of the steering effort required – and showed an even higher compatibility of this adapted model to real-life flight trajectories.But why perform aerial dives given the additional steering effort required, compared with a direct attack from below? Well, for starters, Gonzalez-Bellido and her colleagues discovered that dives provide the fastest route for a first encounter with a victim and that plummeting from above produces a greater impact than attacks mounted from the walls or the floor of the arena. If, in addition, we include that killer flies in the wild are not limited by the size of a laboratory flight arena and would certainly attack again after the first near-miss, there is only one conclusion to make: dives are a powerful attack strategy, but a head start isn't helpful if you are a hungry fly.

Wireless, battery-free, subdermally implantable platforms for transcranial and long-range optogenetics in freely moving animals

Wireless, battery-free, and fully subdermally implantable optogenetic tools are poised to transform neurobiological research in freely moving animals. Current-generation wireless devices are sufficiently small, thin, and light for subdermal implantation, offering some advantages over tethered methods for naturalistic behavior. Yet current devices using wireless power delivery require invasive stimulus delivery, penetrating the skull and disrupting the blood-brain barrier. This can cause tissue displacement, neuronal damage, and scarring. Power delivery constraints also sharply curtail operational arena size. Here, we implement highly miniaturized, capacitive power storage on the platform of wireless subdermal implants. With approaches to digitally manage power delivery to optoelectronic components, we enable two classes of applications: transcranial optogenetic activation millimeters into the brain (validated using motor cortex stimulation to induce turning behaviors) and wireless optogenetics in arenas of more than 1 m2 in size. This methodology allows for previously impossible behavioral experiments leveraging the modern optogenetic toolkit.

Do fine-scale experiments underestimate predator consumption rates?

Understanding ecological processes across spatial scales helps link observations and predictions from experiments to ecological patterns occurring at coarser scales relevant to management and conservation. Using fish, we experimentally manipulated the size of arenas to test the spatial scaling of predator-prey interactions. We measured variation in predator consumption and prey behaviour (prey aggregation, spatial overlap with predators and movement) across arena sizes. Variation in prey behaviour across arena sizes was hypothesized to drive consumption patterns by altering prey vigilance and encounter rates with predators. Per capita consumption and movement were highest in the largest arena relative to the smallest and we observed a mismatch between where bass were present and the highest densities of prey across all arena sizes. We hypothesize more movement in largest arenas increased encounter rates and drove the observed increase in consumption with increasing arena size. Consumption estimates obtained in experimental studies may underestimate consumption, but understanding the mechanisms driving bias across scales helps predict the outcomes of predator-prey interactions in natural systems.

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

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

QED: Using Quality-Environment-Diversity to Evolve Resilient Robot Swarms

In quality-diversity algorithms, the behavioral diversity metric is a key design choice that determines the quality of the evolved archives. Although behavioral diversity is traditionally obtained by describing the observed resulting behavior of robot controllers evaluated in a single environment, it is often more easily induced by introducing environmental diversity, i.e., by manipulating the environments in which the controllers are evaluated. This article proposes quality-environment-diversity (QED), an algorithm that repeatedly generates a random environment according to a probability distribution over environmental features (e.g., number of obstacles, arena size and robot sensor and actuator characteristics), evaluates the controller in that environment, and then describes the controller in terms of the features of that environment, the environment descriptor. Our study compares QED to three baseline task-specific and generic behavioral descriptors, in 5 different robot swarm benchmark tasks. For each task, the quality of the evolved archives is assessed by their capability to provide high-performing compensatory behaviors following injection of 250 unique faults to the robots of the swarm. The evolved archives achieve a median 2- to 3-fold reduction in the impact of the faults on the performance of the swarm. A qualitative analysis of evolved archives is done by visualizing the relation between diversity of compensatory behaviors, here called useful behavioral diversity, and fault recovery metrics. The resulting signatures indicate that, due to the diversity of environments inducing useful behavioral diversity, archives evolved by QED provide robot swarm controllers that are capable of recovering from high-impact faults.

Functional responses are maximized at intermediate temperatures.

Functional responses describe how consumer foraging rates change with resource density. Despite extensive research looking at the factors underlying foraging interactions, there remains ongoing controversy about how temperature and body size control the functional response parameters space clearance (or attack) rate and handling time. Here, we investigate the effects of temperature, consumer mass, and resource mass using the largest compilation of functional responses yet assembled. This compilation contains 2,083 functional response curves covering a wide range of foragers and prey types, environmental conditions, and habitats. After accounting for experimental arena size, dimensionality of the foraging interaction, and consumer taxon, we find that both space clearance rate and handling time are optimized at intermediate temperatures (a unimodal rather than monotonic response), suggesting that the response to global climate change depends on the location of the consumer's current temperature relative to the optimum. We further confirm that functional responses are higher and steeper for large consumers and small resources, and models using consumer and resource masses separately outperformed models using consumer:resource mass ratios, suggesting that consumer and resource body mass act independently to set interaction strengths. Lastly, we show that the extent to which foraging is affected by temperature or mass depends on the taxonomic identity of the consumer and the dimensionality of the consumer-resource interaction. We thus argue that although overall body size and temperature effects can be identified, they are not universal, and therefore food web and community modeling approaches could be improved by considering taxonomic identity along with body size and unimodal temperature effects.

Multi-Location Test of Alternative Pheromone Trap Designs for Sugarcane Early Shoot Borer in South India

As part of ongoing R&D towards improving the adoption of sex pheromone-based trapping of adults of sugarcane moth borers of importance in India, the present studies were taken up to test alternatives to the currently recommended water basin trap being reckoned as not so user-friendly. The results of a multi-location testing of variants of a waterless trap design (Delta Plus) as potential alternatives to water basin trap for attracting the male moths of the sugarcane early shoot borer, Chilo infuscatellus, are illustrated in this paper. The weekly moth catch in water basin trap was compared with two variants of the waterless (Delta Plus) traps for six successive weeks in four replications each at six locations (two research stations and four sugar factory fields) in South India which showed that the two waterless (Delta Plus) trap variants caught nearly fourfold more moths than the water basin trap. Further, the provision of additional access windows (two on either side) was found to enhance the moth catches significantly. Additional testing of Delta Plus with extended sticky arena size (in four locations) also showed the significant increase in moth catches in the larger arena. It is thereby concluded that the waterless trap design (Delta Plus) with access windows is much superior to the water basin traps, with greater moth capturing efficiency and being more user-friendly. The Delta Plus traps are therefore recommended for use in monitoring and/or mass trapping as a key component of integrated pest management for the sugarcane borers.

Design concept of horse arena in Malaysia – A case study

One of the most important facilities required for any equine centre is horse arena. Horse arena is a place where horse doing the execrsice. Its a dedicated riding space is useful for training purposes. Equine Center may include an outdoor arena, indoor arena, or both. This paper presents the findings from a case study on the arena design concept throughout Malaysia. A total of fourtytwo (42) Equine Centre throughout the country were selected and visited in the study. The items studied include the types of arena, size of arena, material used for surface and fencing. The results indicated that about 79% of the arena used outdoor design, 31% of the arena had arena size of 20m x 60m, 56% used Polyvinyl Chloride (PVC) as the main material of fencing, and almost 74% used sand as types of surface in arena. Then for the indoor arena, the design concept of the roof structure was 79% used gable type of design with 81% used zinc as the roofing material. Generally, it can be said that the design concept of the horse arena in Malaysia depends on the owner needs, activities of the equine centre whether it is use for training or game.

Complexity and Innovation. Why Beneficial Effects of Innovation Highly Depend

Mainstream economics and everyday consciousness tend to declare any change an “innovation”. Innovation thus appears as a black box. It seems to lack a criterion to distinguish a counterproductive change – e.g., a dynamic perceived by agents as over-turbulence, or some flawed, misled, and futile “change” under fundamental uncertainty and opacity – from welfare-enhancing innovation proper. Also (Neo-) Schumpeterians, although having pushed complexity economics, appear to always (tacitly at least) consider “creative destruction” to have an excess of “creation” over “destruction” by definition. But insights from complexity sciences and complex adaptive economic systems suggest that “innovation” may be anything between flexible, smooth, improving change and highly idiosyncratic and turbulent motions perceived as over-complex, triggering conservative (“anti-innovative”) Polanyian countermotions by agents (humans and organizations), who are cognitively overburdened. Innovation proper is considered in the present paper a new technique and related behavior solving a defined common or collective problem. We apply the Veblenian or philosophically “pragmatist” criterion of “instrumental” vs. “ceremonial” behavior to provide such a criterion for defined problem constellations. We use a simple game-theoretic formalism in the framework of the “evolution-of-cooperation” approach to clarify and illustrate an instrumental, i.e., collectively problem-solving, innovative behavior overcoming a culture of myopic, hyper-rational individualistic maximization. We explain agency requirements for innovation proper, including cognitive conditions of a corresponding instrumental evolution of institutionalized cooperation in ubiquitous social dilemmas. We then focus on the conditions of the size of the relevant interaction arena and of the co-evolving institutional platform (and its carrier group), and of the network structure.

Arena size modulates functional responses via behavioral mechanisms

Arena size modulates functional responses via behavioral mechanisms

Shape and size of the arenas affect amphipod behaviours: implications for ecotoxicology.

The use of behaviour in ecotoxicology is expanding, however the lack of standardisation and validation of these assays currently presents a major drawback in moving forward in the development of behavioural assays. Furthermore, there is a current paucity of control data on test species, particularly invertebrate models. In this study we assessed a range of behaviours associated with spatial distribution and locomotion in relation to arena size and shape in two species of amphipod crustacean (Echinogammarus marinus and Gammarus pulex). Arena shape had significant effects on almost all behavioural parameters analysed. Increasing arena size resulted in an increased mean velocity and activity plus increased proportional use of the central zones. These results indicate that ‘ceiling effects’ may occur in some ecotoxicological studies resulting in potentially ‘false’ negative effects if careful consideration is not paid to experimental design. Differences in behaviours were observed between the two species of amphipod. For example, G. pulex spend approximately five times (∼20%) more of the available time crossing the central zones of the arenas compared to E. marinus (∼4%) which could have implications on assessing anxiolytic behaviours. The results of this study highlight several behaviours with potential for use in behavioural ecotoxicology with crustaceans but also underscore the need for careful consideration when designing these behavioural assays.