Repeated exposure reduces the response to impulsive noise in European seabass

Human activities have changed the acoustic environment of many terrestrial and aquatic ecosystems around the globe. Mounting evidence indicates that the resulting anthropogenic noise can impact the behaviour and physiology of at least some species in a range of taxa. However, the majority of experimental studies have considered only immediate responses to single, relatively short‐term noise events. Repeated exposure to noise could lead to a heightened or lessened response. Here, we conduct two long‐term (12 week), laboratory‐based exposure experiments with European seabass (Dicentrarchus labrax) to examine how an initial impact of different sound types potentially changes over time. Naïve fish showed elevated ventilation rates, indicating heightened stress, in response to impulsive additional noise (playbacks of recordings of pile‐driving and seismic surveys), but not to a more continuous additional noise source (playbacks of recordings of ship passes). However, fish exposed to playbacks of pile‐driving or seismic noise for 12 weeks no longer responded with an elevated ventilation rate to the same noise type. Fish exposed long‐term to playback of pile‐driving noise also no longer responded to short‐term playback of seismic noise. The lessened response after repeated exposure, likely driven by increased tolerance or a change in hearing threshold, helps explain why fish that experienced 12 weeks of impulsive noise showed no differences in stress, growth or mortality compared to those reared with exposure to ambient‐noise playback. Considering how responses to anthropogenic noise change with repeated exposure is important both when assessing likely fitness consequences and the need for mitigation measures.     

Traffic noise and responses to a simulated approaching avian predator in mixed-species flocks of chickadees,titmice, and nuthatches

Traffic noise likely reaches a wide range of species and populations throughout the world, but we still know relatively little about how it affects anti-predator behavior of populations. We tested for possible effects of traffic noise on responses to predator acoustic cues in Carolina chickadees (Poecile carolinensis), tufted titmice (Baeolophus bicolor), and white-breasted nuthatches (Sitta carolinensis) near 14 independent feeding stations in eastern Tennessee. We compared anti-predator calling and seed-taking behavior in response to playbacks of predator stimuli (screech owl calls) at sites naturally exposed to traffic noise and at sites that faced relatively little traffic noise. The screech owl call playback was designed to simulate the approach of this dangerous predator to a feeder being used by these small songbirds. We found that chickadees responded consistently to the owl stimuli across different levels of traffic noise. However, titmice, and nuthatches exhibited different behavioral responses to the predator stimulus, suggesting that traffic noise masked these low-frequency predator calls. Overall, chickadees and nuthatches showed the broadest anti-predator behavioral responses in comparison to titmice, corroborating earlier published work with an Indiana population. Finally, populations exposed to traffic noise overall seemed less able to detect predator cues potentially masked by that noise, and future work will need to assess likely seasonal variation in these responses as well as species-level variation in anti-predator responses in mixed-species groups.     

Wild fledgling tits do not mob in response to conspecific or heterospecific mobbing calls

Mobbing, where birds harass a predator through a combination of vocalizations and stereotyped behaviours, is an effective anti-predator behaviour for many species. Mobbing may be particularly important for juveniles, as these individuals are often more vulnerable than adults. Although the component behaviours of mobbing are often considered to be un-learned, there are few confirmatory data, and the developmental trajectory of mobbing is unknown. In this study, we tested whether conspecific or heterospecific mobbing calls initiated mobbing behaviour in juvenile Blue Tits Cyanistes caeruleus. We located wild adult and recently fledged juvenile Blue Tits and presented them with playback recordings of adult conspecific (Blue Tit) and heterospecific (Great Tit Parus major) mobbing alarm calls. Although adult birds readily mob in response to these types of playbacks, juveniles did not exhibit characteristic mobbing behaviour. Some juveniles did, however, exhibit individual components of mobbing behaviour found in mobbing, despite not producing adult-like mobbing behaviour in response to either conspecific or heterospecific playback. These results suggest that, although birds might be capable of mobbing as juveniles, the associations between the non-vocal stereotyped mobbing behaviours and mobbing calls may be learned.     

Model vs. playback experiments: The impact of sensory mode on predator-specific escape responses in saki monkeys

Although experimentally simulating predator presence helps improve sample sizes in studies of free-ranging animals, few studies have examined whether auditory playbacks and visual models produce similar results. Additionally, it is unclear if anti-predator strategies are specific to predator hunting styles in understudied Neotropical pitheciid primates, limiting what we can generalize about this phenomenon across this taxonomic order. We conducted predator simulation experiments to assess whether wild Rylands' bald-faced saki monkeys (Pithecia rylandsi) recognize predators based solely on acoustic cues, exhibit predator-specific responses to different predator types, and vary responses to presentations in different sensory modes. In our playback experiments, sakis had weak responses to non-predator control vocalizations compared to jaguar growls and harpy eagle shrieks. In most predator playbacks, subjects' first glance corresponded to the direction from which simulated predators would typically attack (above vs. below). However, although sakis exhibited appropriate movement responses to harpy playbacks (i.e., descending canopy), they exhibited no clear movement patterns when presented with jaguar playbacks. In contrast, jaguar model experiments consistently elicited fast approaches, mobbing-style responses, and long alarm calling bouts. Thus, if we had relied on playbacks alone, we might have concluded that sakis have only generalized responses to terrestrial ambush predators. In fact, in all variables measured (e.g., latency, number of calls, and response duration), models of both predator species elicited stronger reactions than playbacks. Results indicate that bald-faced sakis can identify predators based solely on vocalizations, but do not exhibit predator-specific escape responses to terrestrial predators based on acoustic cues alone. The differential response to playbacks and models calls into question the reliability of using acoustic-only stimuli to assess the specificity of anti-predator behavior to predator hunting styles in some primate species.     

Little Evidence to Support the Risk–Disturbance Hypothesis as an Explanation for Responses to Anthropogenic Noise by Pygmy Marmosets (Cebuella niveiventris) at a Tourism site in the Peruvian Amazon

The risk–disturbance hypothesis states that animals react to human stressors in the same way as they do to natural predators. Given increasing human–wildlife contact, understanding whether animals perceive anthropogenic sounds as a threat is important for assessing the long-term sustainability of wildlife tourism and proposing appropriate mitigation strategies. A study of pygmy marmoset (Cebuella niveiventris) responses to human speech found marmosets fled, decreased feeding and resting, and increased alert behaviors in response to human speech. Following this study, we investigated pygmy marmoset reactions to playbacks of different acoustic stimuli: controls (no playback, white noise and cicadas), anthropogenic noise (human speech and motorboats), and avian predators. For each playback condition, we recorded the behavior of a marmoset and looked at how the behaviors changed during and after the playback relative to behaviors before. We repeated this on ten different marmoset groups, playing each condition once to each group. The results did not replicate a previous study on the same species, at the same site, demonstrating the importance of replication in primate research, particularly when results are used to inform conservation policy. The results showed increased scanning during playbacks of the cicadas and predators compared with before the playback, and an increase in resting after playbacks of avian predators, but no evidence of behavior change in response to playbacks of human speech. There was no effect of ambient sound levels or distance between the playback source and focal animals on their behavior for all playback conditions. Although we find that noise can change the behavior of pygmy marmosets, we did not find evidence to support the risk–disturbance hypothesis.

     

A field test of the audibility of urban versus rural songs in mountain chickadees

Anthropogenic noise can mask avian vocalizations, and several urban‐dwelling species adjust frequency or amplitude of vocalizations in ways that appear to compensate for increased noise levels. Playback studies have investigated whether receivers differentiate between signals produced by rural and urban males, but it is difficult to determine whether differential response to stimulus reflects differences in audibility versus perceived differences in male signals/condition that result from urban settlement. Here, we performed paired‐playback trials to determine whether mountain chickadees (Poecile gambeli) differentiate urban versus rural songs when both stimuli were broadcast within noise. For each playback, stimuli were played in short bouts starting at a low signal‐to‐noise ratio and increasing in relative amplitude with each successive bout. If the primary function of adjusted urban songs is propagation in noise, we hypothesized that focal males would respond sooner to urban versus rural playbacks (detect at lower signal‐to‐noise ratios). If urban songs solely encode information about the male's condition (such as increased aggression), then we predicted only a differential aggressive response to playbacks once detected. If urban songs both increase propagation and embed information on male condition, we predicted a combination of both response types. We found no difference in latency to first response in urban versus rural songs, but some evidence for differential aggression to playback dependent on both stimulus type (urban vs. rural) and local ambient noise levels; focal males in noisy (urban) sites responded aggressively to both stimulus types, whereas focal males in quiet (rural) sites responded more aggressively to urban than to rural stimuli. This context‐dependent discrimination may be the result of increased aggression in urban habitats, improved communication in noisy habitats by urban signallers and receivers, or some combination of the two.     

Computer-manipulated stimuli as a research tool in Mozambique tilapia <Emphasis Type="Italic">Oreochromis mossambicus</Emphasis>

Multimodal communication is essential in social interactions in cichlid fish, including conspecifics’ recognition, agonistic interactions and courtship behaviour. Computer-manipulated image stimuli and sound playback offer powerful tools to assess the relative relevance of visual and acoustic stimuli in fish behavioural studies, but these techniques require validation for each taxon. The aim of the present study was to investigate whether Mozambique tilapia Oreochromis mossambicus responds to computer-manipulated visual stimuli and acoustic playback. Six experiments were conducted: computer animation playback, video playback, interaction with a mirror, presentation of a live male in a jar alone and combined with courting sound playback or with white noise playback. Individual agonistic interactions (lateral displays, up and down swimming, butting) and courting behaviours (tilting leading, digging) were tallied for each experiment. Our results suggest that non-interactive computer-manipulated visual stimuli is not a suitable tool in behavioural research with Mozambique tilapia. In contrast, interaction with a live male in a jar seems to remain the best visual research instrument inducing significant strong behavioural responses. Although none or only a few agonistic interactions were observed towards video playbacks or computer animations, such interactions significantly increased towards a male in jar and were modulated by courtship sound playback, suggesting the additional relevance of sound playback as a tool in behavioural research with Mozambique tilapia, including the study of multimodal signalling.     

Impacts of regular and random noise on the behaviour,growth and development of larval Atlantic cod (Gadus morhua)

Anthropogenic noise impacts behaviour and physiology in many species, but responses could change with repeat exposures. As repeat exposures can vary in regularity, identifying regimes with less impact is important for regulation. We use a 16-day split-brood experiment to compare effects of regular and random acoustic noise (playbacks of recordings of ships), relative to ambient-noise controls, on behaviour, growth and development of larval Atlantic cod (Gadus morhua). Short-term noise caused startle responses in newly hatched fish, irrespective of rearing noise. Two days of both regular and random noise regimes reduced growth, while regular noise led to faster yolk sac use. After 16 days, growth in all three sound treatments converged, although fish exposed to regular noise had lower body width–length ratios. Larvae with lower body width–length ratios were easier to catch in a predator-avoidance experiment. Our results demonstrate that the timing of acoustic disturbances can impact survival-related measures during development. Much current work focuses on sound levels, but future studies should consider the role of noise regularity and its importance for noise management and mitigation measures.     

Experimental Chronic Noise Is Related to Elevated Fecal Corticosteroid Metabolites in Lekking Male Greater Sage-Grouse (Centrocercus urophasianus)

There is increasing evidence that individuals in many species avoid areas exposed to chronic anthropogenic noise, but the impact of noise on those who remain in these habitats is unclear. One potential impact is chronic physiological stress, which can affect disease resistance, survival and reproductive success. Previous studies have found evidence of elevated stress-related hormones (glucocorticoids) in wildlife exposed to human activities, but the impacts of noise alone are difficult to separate from confounding factors. Here we used an experimental playback study to isolate the impacts of noise from industrial activity (natural gas drilling and road noise) on glucocorticoid levels in greater sage-grouse (Centrocercus urophasianus), a species of conservation concern. We non-invasively measured immunoreactive corticosterone metabolites from fecal samples (FCMs) of males on both noise-treated and control leks (display grounds) in two breeding seasons. We found strong support for an impact of noise playback on stress levels, with 16.7% higher mean FCM levels in samples from noise leks compared with samples from paired control leks. Taken together with results from a previous study finding declines in male lek attendance in response to noise playbacks, these results suggest that chronic noise pollution can cause greater sage-grouse to avoid otherwise suitable habitat, and can cause elevated stress levels in the birds who remain in noisy areas.     

Responses of Kamchatkan fish‐eating killer whales to playbacks of conspecific calls

Killer whales produce repertoires of stereotyped call types that are primarily transmitted vertically through social learning, leading to dialects between sympatric pods. The potential function of these call repertoires remains untested. In this study, we compared the reaction of Kamchatkan fish‐eating killer whales to the playbacks of calls from the same and different pods. After the playback of recordings from a different pod, in three cases whales changed the direction of their movement toward the boat, and in three cases no changes in direction were observed. After the playback of recordings from the same pod (either from the same or a different unit within the pod), in seven cases whales changed the direction of their movement toward the boat, and in only one case no change in direction was observed. Whales remained silent after all six playbacks of recordings from a different pod, even when they changed direction toward the boat. After the playback of recordings from the same pod, however, in all eight cases whales started calling in response. Our playback study shows that killer whales may react to playbacks of conspecific sounds and that reactions are dependent on the type of playback stimuli.     

Interactive video playback and opponent assessment in lizards

Video playback has been used to explore many issues in animal communication, but the scope of this work has been constrained by the lack of stimulus-subject interaction. In many natural contexts, each participant's signalling behaviour is dependent from moment-to-moment on that of the other. Analyses of acoustic communication demonstrate the value of reproducing such social contingencies. We assessed the utility of interactive playback for studies of visual signalling by comparing the responses of male Jacky dragons, Amphibolurus muricatus, to interactive and non-interactive digital video playbacks of a life-sized conspecific. Displays produced by lizards in the interactive condition had the effect of suppressing the aggressive display of their simulated opponent. Each stimulus sequence generated during an interactive playback was subsequently played to a size-matched control animal. Males that could interact with the video stimulus responded principally with aggressive displays, while those that could not produced a mixture of aggressive and appeasement signals. Adding a degree of receiver responsiveness is hence sufficient to alter the type of signal evoked, even when video stimuli are physically identical. Interactive playback permits the experimental study of a broader range of theoretical topics and can enhance the realism of video stimuli.     

Interspecific responses to distress calls in bats (Chiroptera: Vespertilionidae): a function for convergence in call design?

Distress calls were recorded from three sympatric species of pipistrelle bat (Pipistrellus nathusii, P. pipistrellus and P. pygmaeus) in England and Northern Ireland. At foraging sites, we conducted playback experiments, consisting of experimental distress call sequences from each species and control sequences of random noise and sound recorded with no bats present. We measured response by simultaneously recording ultrasound during playbacks and counting the echolocation pulses above a predetermined threshold which were then identified to species. All three species responded to each other's calls. The number of recorded echolocation pulses of all species increased eight-fold, on average, during the playback of distress call sequences compared with the playback of ultrasonic noise, and four-fold compared with the playback of silence. In a separate playback experiment, the number of echolocation pulses of P. pygmaeus increased 14-fold during the playback of distress calls of four endemic species of bat from Madagascar (Emballonura atrata, Myotis goudoti, Miniopterus majori and M. manavi) compared with the playback of silence. This increased response might have been caused by the high calling rates of the Malagasy species. Distress calls of P. nathusii, P. pipistrellus and P. pygmaeus were structurally convergent, consisting of a series of downward-sweeping, frequency-modulated elements of short duration and high intensity with a relatively strong harmonic content. Selection may favour convergence in the structure of distress calls among bat species, if attracting heterospecifics increases the chance of repelling predators by mobbing.     

Evaluating the function of the male harbour seal, Phoca vitulina, roar through playback experiments

The aim of this study was to evaluate the role of vocalizations produced during the breeding season by the male harbour seal, an aquatically breeding pinniped. During the spring of 1999, playback experiments were conducted at eight locations in Elkhorn Slough, California, U.S.A. Through an underwater speaker, we presented male harbour seals with three acoustic stimuli: a long-duration, low-frequency roar (LL), a short-duration, high-frequency roar (SH) and amplified water noise (control). Male responses to the playback boat were characterized by increased approach rates and aggressive flipper slapping during 62.5% of SH sessions (N=8), 25% of LL sessions (N=8) and 0% of control sessions (N=8). No more than one identifiable seal responded during each playback location. We observed no responses by female harbour seals to playbacks. We conclude from these experiments that territorial male harbour seals use roars given by intruders to locate and challenge intruders.     

Individuals in foraging groups may use vocal cues when assessing their need for anti-predator vigilance

Many studies of social species have reported variation in the anti-predator vigilance behaviour of foraging individuals depending on the presence and relative position of other group members. However, little attention has focused on how foragers assess these variables. It is commonly assumed that they do so visually, but many social species produce frequent calls while foraging, and these 'close' calls might provide valuable spatial information. Here, we show that foraging pied babblers (Turdoides bicolor) are less vigilant when in larger groups, in the centre of a group and in closer proximity to another group member. We then show that foragers are less vigilant during playbacks of close calling by more individuals and individuals on either side of them when compared with calls of fewer individuals and calls on one side of them. These results suggest that foragers can use vocal cues to gain information on group size and their spatial position within a group. Future studies of anti-predator vigilance should consider the relative importance of both visual and vocal monitoring of group members.     

Stonefly nymphs use hydrodynamic cues to discriminate between prey

Summary Playback experiments conducted in a Rocky Mountain, USA, stream determined whether predatory stonefly nymphs (Kogotus modestus; Plecoptera: PerlodiMae) used hydrodynamic cues to discriminate prey species from nonprey species. In the laboratory we recorded pressure wave patterns associated with swimming escape behavior of Baetis bicaudatus (Baetidae), the favored mayfly prey species, and those of a nonprey mayfly, Ephemerella infrequens (Ephemerellidae). We video taped the responses of 24-h starved Kogotus to Baetis playbacks, Ephemerella playbacks or no playbacks made by oscillating (or not) live mayflies (Ephemerella) or clear plastic models placed within in situ flow-through observation boxes. The probability of attacks per encounter with Baetis playbacks was highest and independent of the model type used, but Kogotus also showed an unexpected high probability of attacks per encounter when Ephemerella playbacks were made through live Ephemerella. Thus, Kogotus discriminated between Baetis and Ephemerella swimming patterns but only when playbacks were made through the plastic model. Kogotus never attacked motionless mayflies or motionless plastic models. We allowed some Kogotus to successfully capture one small Baetis immediately before playbacks, which resulted in a much higher probability of attacks per encounter with Baetis playbacks on either model and a heightened discrimination of prey versus nonprey playbacks. The probability of attacks per encounter by Kogotus with live Baetis swimming under similar experimental conditions was strikingly similar to its response to Baetis playbacks made by oscillating the plastic model after a successful capture. Order of playback presentation (Baetis first or Ephemerella first) did not influence predatory responses to mayfly swimming patterns. This study is the first to document the use of hydrodynamic cues by stream-dwelling predators for discrimination of prey from nonprey and provides a mechanism to explain selective predation by stoneflies on Baetis in nature.     

Dual Function of Chip Calls Depending on Changing Call Rate Related to Risk Level in Territorial Pairs of White‐Eared Ground‐Sparrows

Different mechanisms have been proposed for encoding information into vocalizations: variation of frequency or temporal characteristics, variation in the rate of vocalization production, and use of different vocalization types. We analyze the effect of rate variation on the dual function of chip calls (contact and alarm) produced by White‐eared Ground‐sparrows (Melozone leucotis). We conducted an acoustic playback experiment where we played back 1 min of four chip call rates (12, 36, 60, 84 calls/min). We measured the response of territorial pairs using behavioral responses, and fine structural features of calls produced in response to those playbacks. White‐eared Ground‐sparrows showed more intense behavioral responses to higher than lower call rate playbacks. Both individuals of the pair approached the source of the playback stimulus faster, produced the first vocalization faster, produced more vocalizations, and spent more time close to the stimulus in higher call rate than in lower call rate playbacks. Frequency and duration characteristics of calls (chip and tseet) were similar in response to all call rate playbacks. Our playback experiment elicited different intensity of behavioral responses, suggesting that risk‐based information is encoded in call rate. Our results suggest that variation in the rate of chip call production serves a dual function in this species; calls are used at lower rates for pair contact and at higher rates for alarm/mobbing signals.     

Regulation of vocal amplitude by the blue-throated hummingbird, Lampornis clemenciae

Animals that rely on vocal communication must broadcast sound so that a perceptible signal is transmitted over an appropriate distance. We found that male blue-throated hummingbirds modified the amplitude of their vocalizations in response to both naturally occurring and experimenter-controlled changes in ambient noise levels. This phenomenon is known as the Lombard effect and may increase the efficiency of acoustic signalling. This study demonstrates the effect under natural field conditions and documents the first hummingbird species (Apodiformes: Trochilidae) to show this behaviour. We measured sound pressure levels (SPLs) of Serial Chip territorial advertisement calls across a natural range of ambient noise, primarily due to creeks within male territories. We found a significant correlation between the amplitude of Serial Chips and the amplitude of background noise. To test this relationship, we broadcast recordings of creek noise at high and low amplitudes while target individuals were producing Serial Chip vocalizations. We measured vocal SPLs before and during the playback. Individuals responded to changes in playback creek noise by changing the amplitude of Serial Chip production. We also measured transmission properties of Serial Chip calls through natural habitat to calculate the approximate amplitude of vocalizations at the position of the calling bird. We suggest that amplitude regulation of vocalizations contibutes to signal transmission distance along with the established relationships between singing behaviour, acoustic structure and habitat. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.     

Alarm Calls of Marmosets (Callithrix geoffroyi) to Snakes and Perched Raptors

Communication about the presence of predators is an important benefit of group living. Critical information about the nature of danger can be conveyed through referential alarm calls. Raptors pose a significant predatory threat to callitrichid species. Unlike a raptor in flight, a perched raptor cannot attack suddenly at great speed, and it can be monitored from a safe distance. In this sense a perched bird may pose a threat more similar to that of a terrestrial predator such as a snake. Here we compare predatory contexts by addressing these two questions: 1) Do marmosets produce acoustically distinct alarm calls to snake models and perched raptor models? 2) Do the visual responses of the marmosets to the playbacks of perched raptor–elicited calls differ from those given to the playbacks of calls given in response to snakes? We recorded alarm calls from two groups of outdoor-housed Geoffroy’s marmosets (Callithrix geoffroyi) in response to predator models. Later, we played back stimuli created from these recordings to the marmosets and scored their gaze direction. Results show that calls given to models of perched raptors are acoustically distinct from those given to models of snakes. Further, the relative number of upward to downward looks while listening to the playbacks of perched raptor–elicited calls was significantly greater than it was for snake-elicited calls. Reactions to airborne raptors are known to elicit freezing or rapid flight, neither of which occurred in response to our playbacks. Our data suggest a greater complexity in the alarm call repertoire of marmosets than previously demonstrated.     

Condition-dependent responses of fish to motorboats

Anthropogenic noise is a pollutant of global concern that has been shown to have a wide range of detrimental effects on multiple taxa. However, most noise studies to-date consider only overall population means, ignoring the potential for intraspecific variation in responses. Here, we used field experiments on Australia''s Great Barrier Reef to assess condition-dependent responses of blue-green damselfish (Chromis viridis) to real motorboats. Despite finding no effect of motorboats on a physiological measure (opercular beat rate; OBR), we found a condition-dependent effect on anti-predator behaviour. In ambient conditions, startle responses to a looming stimulus were equivalent for relatively poor- and good-condition fish, but when motorboats were passing, poorer-condition fish startled at significantly shorter distances to the looming stimulus than better-condition fish. This greater susceptibility to motorboats in poorer-condition fish may be the result of generally more elevated stress levels, as poorer-condition fish had a higher pre-testing OBR than those in better condition. Considering intraspecific variation in responses is important to avoid misrepresenting potential effects of anthropogenic noise and to ensure the best management and mitigation of this pervasive pollutant.     

Anthropogenic noise compromises antipredator behaviour in European eels

Increases in noise‐generating human activities since the Industrial Revolution have changed the acoustic landscape of many terrestrial and aquatic ecosystems. Anthropogenic noise is now recognized as a major pollutant of international concern, and recent studies have demonstrated impacts on, for instance, hearing thresholds, communication, movement and foraging in a range of species. However, consequences for survival and reproductive success are difficult to ascertain. Using a series of laboratory‐based experiments and an open‐water test with the same methodology, we show that acoustic disturbance can compromise antipredator behaviour – which directly affects survival likelihood – and explore potential underlying mechanisms. Juvenile European eels (Anguilla anguilla) exposed to additional noise (playback of recordings of ships passing through harbours), rather than control conditions (playback of recordings from the same harbours without ships), performed less well in two simulated predation paradigms. Eels were 50% less likely and 25% slower to startle to an ‘ambush predator’ and were caught more than twice as quickly by a ‘pursuit predator’. Furthermore, eels experiencing additional noise had diminished spatial performance and elevated ventilation and metabolic rates (indicators of stress) compared with control individuals. Our results suggest that acoustic disturbance could have important physiological and behavioural impacts on animals, compromising life‐or‐death responses.