Effects Of Anthropogenic Noise Research Articles

Navigating the Marine Strategy Framework Directive D11: Updates on Threshold Values and Future Perspectives

The Marine Strategy Framework Directive (MSFD), enacted by the European Union in 2008, seeks to achieve a Good Environmental Status for European seas through 11 qualitative descriptors. This paper specifically examines Descriptor 11 (D11), which focuses on the impact of anthropogenic noise on marine ecosystems. Despite significant advancements and extensive work done by expert groups and researchers to establish methodologies for assessing this issue, critical gaps remain, such as the effects of anthropogenic noise on many marine species, including cetaceans. As the second MSFD cycle concludes, this paper emphasizes the need for further research on other forms of energy, such as electromagnetic fields, and advocates for standardized approaches, including a unified Level of Onset of Adverse Biological Effects (LOBE) for species and habitat.

Behavioural response to boat noise weakens the strength of a trophic link in coral reefs

In oceans, the noise generated by human activities has reached phenomenal proportions, with considerable harmful effects on marine life. Measuring this impact to achieve a sustainable balance for highly vulnerable marine ecosystems, such as coral reefs, is a critical environmental policy objective. Here, we demonstrate that anthropogenic noise alters the interactions of a coral reef fish with its environment and how this behavioural response to noise impairs foraging. In situ observations on the Moorea reef revealed that the damselfish Dascyllus emamo reacts to boat passage by moving closer to its coral bommie, considerably reducing the volume of water available to search for prey. Using boat noise playback experiments in microcosms, we studied D. emamo's behaviour and modeled its functional response (FR), which is the relationship between resource use and resource density, when feeding on juvenile shrimps. Similar to field observations, noise reduced D. emamo's spatial occupancy, accompanied by a lower FR, indicating a reduction in predation independent of prey density. Overall, noise-induced behavioural changes are likely to influence predator-prey interaction dynamics and ultimately the fitness of both protagonists. While there is an urgent need to assess the effect of anthropogenic noise on coral reefs, the ecological framework of the FR approach combined with behavioural metrics provides an essential tool for evaluating the cascading effects of noise on nested ecological interactions at the community level.

Sound reception and hearing capabilities in the Little Penguin (Eudyptula minor): first predicted in-air and underwater audiograms.

Despite increasing concern about the effects of anthropogenic noise on marine fauna, relevant research is limited, particularly in those inaccessible species, such as the Little Penguin (Eudyptula minor). In this study, we collected freshly deceased Little Penguins for dissection and micro-computed tomography (microCT) scans. The head structures, including the ear apparatus, were reconstructed based on high-resolution imaging data for the species. Moreover, three-dimensional finite-element models were built based on microCT data to simulate the sound reception processes and ear responses to the incident planar waves at the selected frequencies. The received sound pressure fields and motion (i.e. displacement and velocity) of the internal ear-related structures were modelled. The synergistic response of ear components to incident aerial and underwater sounds was computed to predict the hearing capabilities of the Little Penguins across a broad frequency range (100 Hz-10 kHz), both in air and under water. Our predicted data showed good agreement with other diving birds in both the form and range of auditory sensitivity. This study demonstrates a promising method to study hearing in other inaccessible animals. The outputs from this study can inform noise impact mitigation and conservation management.

The importance of investigating the impact of simultaneous anthropogenic stressors: the effects of rising temperatures and anthropogenic noise on avian behaviour and cognition

Rising temperatures and anthropogenic noise are two of the most pervasive and well researched anthropogenic stressors affecting avian species globally. Despite often triggering similar behavioural responses in birds, and frequently co‐occurring (particularly in urban areas), the impact of these stressors are primarily investigated in isolation. Here, we discuss and compare the most commonly researched effects of anthropogenic noise and rising temperatures on avian behaviour. We then outline recent findings on the impacts of these two stressors on cognition in birds, which underpins many behavioural adjustments. We find that both anthropogenic noise and high temperatures, when investigated in isolation, impact avian behaviours such as foraging, the antipredator response, and interactions with conspecifics. We also find that both these stressors can lead to cognitive impairment, but the occurrence and magnitude of impairment varies depending on the cognitive trait examined. Finally, we discuss the limited studies that have investigated these two anthropogenic stressors simultaneously and outline different scenarios in which additive, synergistic, or antagonistic effects of these stressors may occur. We hope our review will stimulate researchers to investigate the simultaneous effects of these and other anthropogenic stressors on the behaviour and cognition of urban‐living wild birds.

Noise pollution causes parental stress on marine invertebrates, the Giant scallop example

In marine invertebrates, abiotic stresses on adults can act directly on gametes quality, which impacts phenotype and development success of the offspring. Human activities introduce noise pollution in the marine environment but still few studies on invertebrates have considered the impacts on adult or larval stages separately, and to our knowledge, never investigated the cross-generational effects of anthropogenic noise. This article explores parental effects of pile driving noise associated with the building phase of offshore wind turbines on a coastal invertebrate, Pecten maximus (L.). Adults were exposed to increasing levels of sound during gametogenesis, then their offspring were also exposed. The results highlight that anthropogenic noise experienced by the parents reduces their reproductive investment and modify larval response in similar conditions. Also, larvae from exposed adults grew 6-fold faster and metamorphosed 5-fold faster, which could be an amplified adaptive strategy to reduce the pelagic phase in a stressful environment.

Anthropogenic noise effects on Risso's dolphin vocalizations in the Gulf of Taranto (Northern Ionian sea, central Mediterranean sea)

Anthropogenic noise may significantly affect marine mammals' vocalizations. The aim of this work is to describe for the first time the acoustic features of the click trains, buzzes, burst pulses and whistles produced by the Risso's dolphins in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean), the concurrent levels of noise to which dolphins are exposed, and the potential reactive changes in the acoustic structure of the species vocalizations. About 6 h of recordings were collected from April 2019 to September 2022 during daytime boat surveys. Elevated ambient noise levels were mainly present at the frequencies lower than 63 Hz, at about 1 kHz and 50 kHz likely attributable to anthropogenic activity, such as shipping and sonars. Even if the acoustic features of all the vocalizations can be disrupted, especially with increasing noise below 1 kHz and between 20 and 63 kHz, the click trains were the most affected vocalizations, showing changes in their Inter-Click-Interval and in the Peak Amplitude. Since these vocalizations are used for navigation and searching for prey, their alteration raises concerns on the potential negative effects on the well-being of the Risso's dolphin population in the Gulf of Taranto.

The effects of anthropogenic noise on frogs housed on exhibit at a public aquarium.

Anuran behavior and reproduction are dominated by vocalizations, rendering them vulnerable to the effects of signal masking. For anurans on display in zoos and aquaria, a major source of ambient noise is visitors, which pose a unique source of potential anthropogenic signal masking. Call characteristics (total call duration, and minimum and maximum call frequencies) of three populations of dendrobatids (Dendrobates leucomelas, Epipedobates tricolor, and Ranitomeya imitator) on public display were investigated at time periods of increasing visitor-related noise (closed, off-peak, and peak aquarium visiting hours) to determine if there were changes in call characteristics that correlated with changes in visitor noise levels. The data revealed that call length increased with more visitor noise for D. leucomelas and E. tricolor, with their longest calls during peak hours, and all three species had their shortest calls during closed hours. Both minimum and maximum call frequencies increased with more visitor noise for E. tricolor and R. imitator, with their highest frequencies during peak hours, and lowest frequencies during closed hours. This study found evidence that anurans on public display adjust their vocalizations in the presence of visitor noise. These findings support expanded monitoring of ambient noise for animals on public display to determine if noise poses significant effects that might influence well-being or reproduction.

Difference in acoustic responses to urbanisation in two African passerines

Modification of ecosystems as a consequence of urbanisation alters natural habitat structures and soundscapes, creating constraints for vocal communication in animals. Birds are able to adjust their vocalisation to the prevailing acoustic features of their habitat. As such, their sounds have been shown to reflect the level of anthropogenic disturbances across landscapes. While the effect of a single anthropogenic disturbance like ambient noise on birds’ vocal communication is widely investigated, the combined effects of various disturbances remain less explored. We tested single and combined effects of anthropogenic noise and urban physical structures on the vocalisations of two African passerines, the Common Bulbul Pycnonotus barbatus and Northern Grey-headed Sparrow Passer griseus. We predicted that (i) both species would increase the minimum frequency of their vocalisation to avoid masking by ambient noise, (ii) both species would decrease their maximum frequency to evade distortion by physical structures, (iii) the two urban components would have a significant combined effect on the vocalisations, and (iv) the change in minimum or maximum frequency will lead to a corresponding change in the vocalisation bandwidth. For the Common Bulbul, the minimum frequency increased significantly as the ambient noise level increased, but the maximum frequency did not change in response to urban physical structures. For the Northern Grey-headed Sparrow, the minimum frequency did not show a response to ambient noise, but the maximum frequency decreased significantly as physical structures and ambient noise increased. We did not find any evidence for a combined effect of urban physical structures and ambient noise on the vocal adjustment of either species. A change in either the minimum or maximum frequency resulted in a corresponding change in the vocalisation bandwidth of each species. Our findings highlight how the same vocalisation traits of different songbird species can be affected differently by novel selective pressures in acoustic communication that arise in urban environments.

Effects from particle motion and substrate-borne vibration on fishes and invertebrates: Recommendations on research questions and methodologies

There have been substantially increased interest in effects of particle motion and substrate-borne vibration on fishes and aquatic invertebrates over the past decade. This is because these signals, unlike sound pressure, are the basis of hearing in most fishes and in all aquatic invertebrates. However, studies to address these issues continue to face challenges due to the diversity of species, the broad range of hearing mechanism, and the complexity of the physical acoustic environment in conducting studies. Additionally, we do not yet have a good understanding of, and mechanisms for, source generation, calibration, and measurements to be able to examine effects properly. Related to this is the critical issue is how research questions are applicable to regulatory agencies. In October 2023, the US Bureau of Ocean Energy Management held a workshop to address different research methodologies and their pros and cons as the basis for study of the behavioral and physiological responses to particle motion and substrate-borne vibration. Subsequently, a review was conducted linking research priorities previously identified concerning anthropogenic noise effects on animals with appropriate research methodologies. The review also provides recommendations on experimental settings that are most appropriate to address specific research questions for regulatory concerns.

Acoustic monitoring of marine environmental quality: An example from the Estuary and Gulf of St. Lawrence

As a part of the Canada’s Ocean Protection Plan, Fisheries and Oceans Canada has joined the efforts to better understand and monitor the effects of anthropogenic noise on marine environmental quality. Since 2017, underwater acoustic observatories were put in place across endangered whale habitats leading to the acquisition of big underwater acoustic dataset to process and analyze. In the Estuary and Gulf of St. Lawrence, underwater noise has been continuously monitored at 13 locations (6 to 10 simultaneously) between 2018 and 2023 at sampling rate up to 256 ksps in order to better understand the effect of shipping noise on marine environmental quality of the endangered St. Lawrence estuary beluga habitat. In this presentation, the data analysis pipeline from in situ sampling to processing is detailed, including recording schemes, data quality and control, soundscape cube, source separation, multi-scale statistics on noise levels and risk of impacts on habitat quality and visualization. These steps are used to identify, characterize and quantify daily to interannual spectral variability of underwater noise and their relationship with local environmental forcings such as shipping, wind, ice, tides, and currents at targeted locations. Ultimately, these results are used to provide support to (1) marine conservation and spatial planning initiatives from DFO and the Saguenay St. Lawrence Marine Parc; and (2) assess the predictability power of the outputs of soundscape modeling.

Characterization of anthropogenic noise and oyster toadfish (Opsanus tau) calling behavior in urban and small-town coastal soundscapesa).

The oyster toadfish (Opsanus tau) is an ideal model to examine the effects of anthropogenic noise on behavior because they rely on acoustic signals for mate attraction and social interactions. We predict that oyster toadfish have acclimated to living in noise-rich environments because they are common in waterways of urban areas, like New York City (NYC). We used passive acoustic monitoring at two locations to see if calling behavior patterns are altered in areas of typically high boat traffic versus low boat traffic (Pier 40, NYC, NY, and Eel Pond, Woods Hole, MA, respectively). We hypothesized that toadfish in NYC would adjust their circadian calling behavior in response to daily anthropogenic noise patterns. We quantified toadfish calls and ship noise over three 24-h periods in the summer reproductive period at both locations. We observed an inverse relationship between the duration of noise and the number of toadfish calls at Pier 40 in comparison to Eel Pond. Additionally, toadfish at Pier 40 showed significant differences in peak calling behavior compared to Eel Pond. Therefore, oyster toadfish may have acclimated to living in an urban environment by potentially altering their communication behavior in the presence of boat noise.

Roost characteristics of Indian flying fox along urban noise gradient: A case study in Sallaghari Forest, Kathmandu Valley, Nepal

The Indian flying fox, Pteropus medius is a fruit bat that contributes significantly to seed dispersal and pollination services. These bats face serious threats from the loss of roosting trees due to urbanization and deforestation. This study aimed to assess the roost characteristics of Indian flying foxes and the effects of anthropogenic noise on roost tier selection in an urban forest patch. We carried out population surveys of Indian flying foxes in the Sallaghari Forest in Kathmandu Valley, Nepal by direct roost count method from July to November 2023. Further, we quantified the intensities of anthropogenic noise at every five-meter interval along the transects from the forest edge towards the main forest and recorded the minimum roosting heights at each point. Indian flying foxes were found to be roosting on trees belonging to six species. Eucalyptus sp. was the most abundant roost tree (50%) in the forest whereas the highest relative abundance of roosting Indian flying foxes was on Populus ciliata (40.1%). The regression analysis revealed that tree DBH and height and the combined interaction of height and canopy cover significantly increase the abundance of Indian flying foxes. The noise intensity at ground level and roosting height of Indian flying foxes showed a significant strong positive relationship indicating their roosting at higher tier under intense noise. We recommend measures for reducing anthropogenic noises and conserving large and tall trees to ensure the roosting habitat of Indian flying foxes in urban setups.

The effects of anthropogenic noise and urban habitats on song structure in a vocal mimic; the gray catbird (Dumetella carolinensis) sings higher frequencies in noisier habitats

In urban and human-modified landscapes, animals face novel selection pressures resulting from differences in habitat structure and increased anthropogenic noise. Urban noise pollution can negatively impact songbirds because low-frequency noise often masks portions of birds’ mating signals and reduces signal transmission. Previous research has demonstrated that the songs of birds in more urban habitats have structural differences that can enhance signal transmission when noise is present. The majority of these studies have focused on species that deliver short, stereotyped songs and have limited repertoires. Gray catbirds (Dumetella carolinensis, family: Mimidae) sing long bouts containing imitated, improvised, and invented song elements, and therefore may have an increased ability to vary songs in response to noise. We hypothesized that aspects of developed habitats including loud anthropogenic noise and changes to land cover would impact catbirds’ song structural parameters, including song minimum, peak, and maximum frequency, frequency bandwidth, and entropy. We recorded and processed songs from 42 male catbirds and analyzed over 18,000 song elements from sites along an urban gradient from western Virginia to the Washington, DC metropolitan region. We quantified the urban intensity at each site-centroid based on percent canopy cover, percent impervious surface, and noise level. Song features such as minimum, maximum, and peak frequency increased significantly as noise levels increased, demonstrating that catbirds in noisier areas sing higher frequency songs compared to individuals in quieter habitats. Land cover variables also significantly predicted certain song features such as maximum frequency (impervious surface) or entropy (canopy cover). These structural differences in catbird song can limit the negative effects of environmental noise-masking, even for their long song bouts, and suggest that vocal mimics respond to anthropogenic noise. Future studies could investigate repertoire size and composition along an urban gradient and if these structural differences lead to functional consequences for the songs of vocal mimics.

Stay here, but keep quiet: the effects of anthropogenic noise on Guiana dolphins (Sotalia guianensis) in southeastern Brazil

Stay here, but keep quiet: the effects of anthropogenic noise on Guiana dolphins (Sotalia guianensis) in southeastern Brazil

Cognition mediates response to anthropogenic noise in wild Western Australian magpies (Gmynorhina tibicen dorsalis).

Anthropogenic noise is a pollutant of growing concern, with wide-ranging effects on taxa across ecosystems. Until recently, studies investigating the effects of anthropogenic noise on animals focused primarily on population-level consequences, rather than individual-level impacts. Individual variation in response to anthropogenic noise may result from extrinsic or intrinsic factors. One such intrinsic factor, cognitive performance, varies between individuals and is hypothesised to aid behavioural response to novel stressors. Here, we combine cognitive testing, behavioural focals and playback experiments to investigate how anthropogenic noise affects the behaviour and anti-predator response of Western Australian magpies (Gymnorhina tibicen dorsalis), and to determine whether this response is linked to cognitive performance. We found a significant population-level effect of anthropogenic noise on the foraging effort, foraging efficiency, vigilance, vocalisation rate and anti-predator response of magpies, with birds decreasing their foraging, vocalisation behaviours and anti-predator response, and increasing vigilance when loud anthropogenic noise was present. We also found that individuals varied in their response to playbacks depending on their cognitive performance, with individuals that performed better in an associative learning task maintaining their anti-predator response when an alarm call was played in anthropogenic noise. Our results add to the growing body of literature documenting the adverse effects of anthropogenic noise on wildlife and provide the first evidence for an association between individual cognitive performance and behavioural responses to anthropogenic noise.

Finite-element modeling on noise impacts and hearing in marine fauna

Despite increasing interest in the effects of anthropogenic noise on marine fauna, relevant research is limited, particularly in those inaccessible species. Unfortunately, some of these inaccessible species are endangered, such as the little penguins (Eudyptula minor) and Australian sealions (Neophoca cinerea). In this study, we collected freshly deceased bight redfish (Centroberyx gerrardi), little penguins, and Australian sealion for medical computed tomography (CT)/microCT scans. Ear structures were reconstructed based on high-resolution imaging data for the three species. Moreover, 3D finite-element models were built to simulate the sound reception processes and ear responses to the incident planar waves from various directions toward the heads. The received sound pressure levels and motion (e.g., displacement and acceleration) of the internal ear related structures were computed. The data was used to predict the absolute hearing curves of the little penguins and Australian sealions. Our results also indicate that the motion difference plus the geometry of the otoliths plays an important role in the fish otoliths' response to incident sounds from different directions, resulting in different levels of damage to the hair cells. This study may potentially aid researchers in investigating the hearing of some other marine animals.

From ocean ambient noise to soundscape ecology

Ambient noise in the ocean has been studied for more than 80 years but recently there has been a tendency to use the word “soundscape” for what appears to be the same phenomenon. Ambient noise is usually defined as the background noise from all sources, excluding sounds from individual identifiable sources and is an important limitation on sonar performance and the use of sound by marine animals. The term “soundscape” has been used for decades outside of underwater acoustics with varying definitions depending on the application. Probably the most relevant is “soundscape ecology,” which comes from terrestrial ecology and includes the acoustic interaction between animals and between animals and their environment. A soundscape, therefore, includes all sounds in an environment, not just the background or ambient noise. Sounds from individual identifiable sources may have particular interest to marine animals especially if they are from conspecifics, predators, or prey. This paper discusses the value of applying the broader concepts of soundscapes and soundscape ecology to the underwater environment, the advantages of recognizing the distinction between soundscapes and ambient noise and the importance of soundscape ecology in understanding animal acoustic behavior and the effects of anthropogenic noise.

The silent assumption of the masking hypothesis: avian auditory processing and implications for behavioral responses to anthropogenic noise

Anthropogenic noise and its impact on wildlife has recently received considerable attention. Research interest began to increase at the turn of the century and the number of publications investigating the effects of anthropogenic noise has been growing steadily ever since. Songbirds have been a major focus in the study of anthropogenic noise effects, with a significant portion of the literature focusing on the changes in singing behavior in noise. Many of these studies have found increases in the amplitude or frequency of song, or changes in the temporal patterning of song production, putatively due to the masking effects of noise. Implicit in the masking hypothesis is the assumption that all species process sounds in noise similarly and will therefore be subject to similar masking effects. However, the emerging comparative literature on auditory processing in birds suggests that there may be significant differences in how different species process sound, both in quiet and in noise. In this paper we will (1) briefly review the literature on anthropogenic noise and birds, (2) provide a mechanistic overview of how noise impacts auditory processing, (3) review what is known about the comparative avian auditory processing in noise, and (4) discuss the implications of species level differences in auditory processing for behavioral and physiological responses to anthropogenic noise.

Effects of anthropogenic noise and natural soundscape on larval fish behavior in four estuarine species.

The larval and post-larval forms of many marine organisms, such as oysters, crabs, lobster, coral, and fish, utilize ambient acoustic cues to orient, settle, or metamorphose. In this study, the effect of anthropogenic and ambient sounds on the orientation behavior of four larval estuarine fishes was examined in a controlled, laboratory experiment. Pre-settlement size red drum Sciaenops ocellatus, southern flounder Paralichthys lethostigma, spotted seatrout Cynoscion nebulosus, and Florida blenny Chasmodes saburrae larvae were exposed to four sound treatments-control, estuarine soundscape, seismic airguns, and large-ship passage-in a linear acoustic chamber. Initial significant (p < 0.05) avoidance of airguns was observed in three of the four species (all but the Florida blenny), but habituation to this sound occurred as the experiment progressed. All species avoided ship passage sounds; however, the avoidance behavior was not significant. Interestingly, none of the species studied were significantly attracted to the acoustic cues alone of the estuarine soundscape; in fact, three of the four species spent less time near the speaker when it was broadcast. These results suggest that larval fish can potentially habituate to anthropogenic noise relatively quickly (<10 min). Understanding how sounds affect larval behavior is necessary because successful recruitment ultimately affects a population's success.

The effect of anthropogenic noise on foraging and vigilance in zoo housed pied tamarins

The phenomenon of human-induced rapid environmental change (HIREC) is a great challenge in the modern world that presents a threat to all species. Research on the effect of anthropogenic noise on free-living wildlife is increasing but the effect of anthropogenic noise on the behaviour and welfare of captive wildlife has received limited attention, even though captive settings are full of human activity and a wide range of sounds. Moreover, studies in captivity tend to classify noise subjectively by volume according to human hearing and as part of the overall ‘visitor effect’ rather than a stressor in its own right. Research on free-living wildlife suggests that anthropogenic noise can negatively impact foraging behaviour; similar impacts in captive species could have a detrimental effect on their health and welfare if animals cannot perform functional feeding behaviours and access adequate nutrition. In the current study, we designed a forage box experiment for captive pied tamarins, a Critically Endangered callitrichid primate species that is prone to poor physical health and breeding success in captivity. Ten pairs of tamarins housed at Jersey Zoo were provided with a forage box containing cryptic (hidden) prey items (waxworms). Using a within-subjects design, tamarins were provided access to the forage box in noise and non-noise conditions of anthropogenic noise (machinery used for gardening in the zoo). Both active (foraging with the hands) and observational (looking into the forage box) foraging were significantly less frequent in the presence of anthropogenic noise; however, there was no difference in the duration of these behaviours or in foraging success. Furthermore, the presence of anthropogenic noise did not significantly affect vigilance behaviour. We found no sex differences in the effect of noise, and our results suggest that the anthropogenic noise we tested was only a minimal distractor for tamarins. However, large individual differences in foraging suggest that other factors may have a larger impact on foraging than the anthropogenic noise used in this experiment. More research into how captive animals may respond to the presence of anthropogenic noise is needed.