Predicting the effects of anthropogenic noise on fish reproduction

Aquatic animals use and produce sound for critical life functions, including reproduction. Anthropogenic noise is recognized as a global source of environmental pollution and adequate conservation and management strategies are urgently needed. It becomes therefore critical to identify the reproductive traits that render a species vulnerable to acoustic disturbances, and the types of anthropogenic noise that are most likely to impact reproduction. Here, we provide predictions about noise impact on fish reproduction following a two-step approach: first, we grouped documented effects of noise into three mechanistic categories: stress, masking and hearing-loss, and test which type of noise (continuous vs intermittent and regular vs irregular) was most likely to produce a significant response in each category with either a meta-analysis or a quantitative review, depending on data availability. Second, we reviewed existing literature to predict which reproductive traits would render fish most sensitive to stress, masking and hearing-loss. In step one, we concluded that continuous sounds with irregular amplitude and/or frequency-content (e.g. heavy ship traffic) were most likely to cause stress, and continuous sounds were also most likely to induce masking and hearing-loss. From step two we concluded that the vulnerability of a species to noise-induced stress will mainly depend on: (1) its potential to reallocate reproduction to more quiet times or locations, and (2) its vulnerability to masking and hearing-loss mainly on the function of sound communication in its reproductive behaviour. We discuss in which stages of reproduction fish are most likely to be vulnerable to anthropogenic noise based on these findings.publishedVersio

Habitat-related birdsong divergence: a multi-level study on the influence of territory density and ambient noise in European blackbirds

Song plays an important role in avian communication and acoustic variation is important at both the individual and population level. Habitat-related variation between populations in particular can reflect adaptations to the environment accumulated over generations, but this may not always be the case. In this study, we test whether variation between individuals matches local conditions with respect to noise level and territory density to examine whether short-term flexibility could contribute to song divergence at the population level. We conducted a case study on an urban and forest population of the European blackbird and show divergence at the population level (i.e. across habitats) in blackbird song, anthropogenic noise level and territory density. Unlike in several other species, we found a lack of any correlation at the individual level (i.e. across individuals) between song features and ambient noise. This suggests species-specific causal explanations for noise-dependent song differentiation which are likely associated with variation in song-copying behaviour or feedback constraints related to variable singing styles. On the other hand, we found that at the level of individual territories, temporal features, but not spectral ones, are correlated to territory density and seasonality. This suggests that short-term individual variation can indeed contribute to habitat-dependent divergence at the population level. As this may undermine the potential role for song as a population marker, we conclude that more investigations on individual song flexibility are required for a better understanding of the impact of population-level song divergence on hybridisation and speciation

Marine mammals and sonar : dose-response studies, the risk-disturbance hypothesis and the role of exposure context

This manuscript was written following the Behavioral Response Research Evaluation Workshop (BRREW), jointly sponsored by the US Office of Naval Research, US Navy Living Marine Resources, and US National Oceanic and Atmospheric Administration - National Marine Fisheries Service. PLT acknowledges funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland). MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.1. Marine mammals may be negatively affected by anthropogenic noise. Behavioural response studies (BRSs) aim to establish a relationship between the exposure dose of a stressor and associated behavioural responses of animals. A recent series of BRSs have focused on the effects of naval sonar on cetaceans. Here we review the current state of understanding of the impact of sonar on marine mammals and highlight knowledge gaps and future research priorities. 2. Many marine mammal species exhibit responses to naval sonar. However, responses are highly variable between and within individuals, species and populations, highlighting the importance of context in modulating dose-response relationships. 3. There is increasing support for the risk-disturbance hypothesis as an underlying response mechanism. This hypothesis proposes that sonar sounds may be perceived by animals as a threat, evoking an evolved anti-predator response. An understanding of responses within both the dose-response and risk-disturbance frameworks may enhance our ability to predict responsiveness for unstudied species and populations. 4. Many observed behavioural responses are energetically costly, but the way in which these responses may lead to long-term individual and population level impacts is poorly understood. Synthesis and Applications Behavioural response studies have greatly enhanced our understanding of the potential effects of navy sonar on marine mammals. Despite data gaps, we believe a dose-response approach within a risk-disturbance framework will enhance our ability to predict responsiveness for unstudied species and populations. We advocate for (1) regulatory frameworks to utilise recent peer-reviewed research findings when making predictions of impact (where feasible within assessment cycles), (2) regulatory frameworks to account for the inherent uncertainty in predictions of impact, and (3) investment in monitoring programmes that are both directed by recent research and offer opportunities for validation of predictions at the individual and population level.Publisher PDFPeer reviewe

Vocal foragers and silent crowds : context-dependent vocal variation in Northeast Atlantic long-finned pilot whales

This study was financially supported by the US Office of Naval Research, The Netherlands Ministry of Defence, the Norwegian Research Council and the Norwegian Ministry of Defence.Vocalisations form a key component of the social interactions and foraging behaviour of toothed whales. We investigated changes in calling and echolocation behaviour of long-finned pilot whales between foraging and non-foraging periods, by combining acoustic recordings and diving depth data from tagged individuals with concurrent surface observations on social behaviour of their group. The pilot whales showed marked vocal variation, specific to foraging and social context. During periods of foraging, pilot whales showed more vocal activity than during non-foraging periods (rest, travel). In addition to the expected increase in echolocation activity, call rates also increased, suggesting that pilot whales communicate more during foraging. Furthermore, calls with multiple inflections occurred more often immediately before and after foraging dives and during the early descent and late ascent phases of foraging dives. However, these calls were almost never detected at diving depths of the tagged whale beyond 350 m. Calls with no or few inflections were produced at all times, irrespective of diving depth of the tagged whale. We discuss possible explanations for the distinct vocal variation associated with foraging periods. In addition, during non-foraging periods, the pilot whales were found to be more silent (no calling or echolocation) in larger, more closely spaced groups. This indicates that increased levels of social cohesion may release the need to stay in touch acoustically. Significance statement: Social toothed whales rely on vocalisations to find prey and interact with conspecifics. Species are often highly vocal and can have elaborate call repertoires. However, it often remains unclear how their repertoire use correlates to specific social and behavioural contexts, which is vital to understand toothed whale foraging strategies and sociality. Combining on-animal tag recordings of diving and acoustic behaviour with observations of social behaviour, we found that pilot whales produce more calls during foraging than during non-foraging periods. Moreover, highly inflected calls were closely associated to the periods around and during foraging dives. This indicates enhanced communication during foraging, which may, for example, enable relocation of conspecifics or sharing of information. Whales reduced their vocal activity (calling and echolocation) at increased levels of social cohesion, indicating that in certain behavioural contexts, closer association (i.e. more closely spaced) may release the need to stay in touch acoustically.Publisher PDFPeer reviewe

Geschiedenis van de bioakoestiek in technologisch perspectief

The study of acoustic communication between animals forms an important theme in research into behavioural biology at universities around the world. Particularly bird sounds have therefore been studied and continue to be studied in the Netherlands, and they are also extremely popular among amateur sound-hunters. As a result of technological developments over the last century in the fields of sound recording, production and processing quite a number of technical tools have become available to scientists as well as hobbyists. This article briefly describes the contribution of several historically important biologists and a selection of discoveries about and insights into the vocal language of animals. The examples have been chosen to illustrate how scientific progress has been made as a result of technological advancement. The article concludes with a short summary about how the acoustic medium is being exploited by several groups of people in modern society to gain and share knowledge, and above all to enjoy the beauty and diversity of sounds from the natural world

Pollution going multimodal: the complex impact of the human-altered sensory environment on animal perception and performance

Anthropogenic sensory pollution is affecting ecosystems worldwide. Human actions generate acoustic noise, emanate artificial light and emit chemical substances. All of these pollutants are known to affect animals. Most studies on anthropogenic pollution address the impact of pollutants in unimodal sensory domains. High levels of anthropogenic noise, for example, have been shown to interfere with acoustic signals and cues. However, animals rely on multiple senses, and pollutants often co-occur. Thus, a full ecological assessment of the impact of anthropogenic activities requires a multimodal approach. We describe how sensory pollutants can co-occur and how covariance among pollutants may differ from natural situations. We review how animals combine information that arrives at their sensory systems through different modalities and outline how sensory conditions can interfere with multimodal perception. Finally, we describe how sensory pollutants can affect the perception, behaviour and endocrinology of animals within and across sensory modalities. We conclude that sensory pollution can affect animals in complex ways due to interactions among sensory stimuli, neural processing and behavioural and endocrinal feedback. We call for more empirical data on covariance among sensory conditions, for instance, data on correlated levels in noise and light pollution. Furthermore, we encourage researchers to test animal responses to a full-factorial set of sensory pollutants in the presence or the absence of ecologically important signals and cues. We realize that such approach is often time and energy consuming, but we think this is the only way to fully understand the multimodal impact of sensory pollution on animal performance and perception

Behavioural Ecology: Noise Annoys at Community Level

SummaryA new study on the impact of anthropogenic noise on birds takes a behavioural discipline to the level of community ecology: noise can not only harm individual species but also alter species relationships