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Hydromorphological descriptors such as substrate type, water depth, and velocity are commonly used to describe fish habitat, but few studies have focused on how underwater sounds affect habitat use by freshwater fish. We evaluated the influence of the underwater soundscape and other habitat descriptors on the spatial distribution of brook trout (Salvelinus fontinalis) in a small stream in eastern Canada. Habitat measurements were made at high spatial resolution (2.5 m intervals). High acoustical heterogeneity of stream habitats (40-150 dB re 1 [micro]Pa) was related to differences in water velocity and depth as expected from theory. Brook trout densities were positively related to broadband sound pressure levels (SPL), irrespective of water velocity and depth, but in interaction with habitat type. The positive relationship between brook trout densities and SPL could be related to the high auditory threshold of salmonid fishes. Alternatively, brook trout may use the underwater soundscape to select favourable feeding habitats. Underwater sounds integrate the many environmental dimensions of a stream and may be used by fish as cues for habitat selection. Si des descripteurs hydromorphologiques comme le type de substrat et la profondeur et la vitesse de l'eau sont communement utilises pour decrire l'habitat des poissons, peu d'etudes se sont interessees a l'incidence des sons subaquatiques sur l'utilisation de l'habitat par les poissons d'eau douce. Nous avons evalue l'influence du paysage sonore subaquatique et d'autres descripteurs de l'habitat sur la repartition spatiale des ombles de fontaine (Salvelinus fontinalis) dans un petit cours d'eau de l'est du Canada. Les mesures de parametres de l'habitat ont ete prises a haute resolution spatiale (intervalles de 2,5 m). Une forte heterogeneite acoustique des habitats du cours d'eau (40-150 dB, niveau de reference : 1 [micro]Pa) etait reliee a des variations de la vitesse et de la profondeur de l'eau, comme permettent de la predire des considerations theoriques. Les densites d'ombles de fontaine etaient positivement reliees aux niveaux de pression acoustique (NPA) de large bande, independamment de la vitesse et de la profondeur de l'eau, mais en interaction avec le type d'habitat. La relation positive entre les densites d'ombles de fontaine et les NPA pourrait etre associee au seuil d'audition eleve des salmonides. Par ailleurs, les ombles de fontaine pourraient utiliser le paysage sonore subaquatique pour selectionner des habitats d'alimentation favorables. Les sons subaquatiques integrent les nombreuses dimensions environnementales d'un cours d'eau et pourraient etre utilises par les poissons comme indices pour la selection d'habitats. [Traduit par la Redaction], Introduction Under natural conditions, underwater habitats that range from quiet shallow lakes to fast-flowing cascades show a rich mosaic of sounds (Amoser and Ladich 2005; Wysocki et al. 2007a). Lotic [...]

Acoustic metrics (AM) assist our interpretation of acoustic environments by aggregating a complex signal into a unique number. Numerous AM have been developed for terrestrial ecosystems, with applications ranging from rapid biodiversity assessments to characterizing habitat quality. However, there has been comparatively little research aimed at understanding how these metrics perform to characterize the acoustic features of marine habitats and their relation with ecosystem biodiversity. Our objectives were to 1) assess whether AM are able to capture the spectral and temporal differences between two distinct Antarctic marine acoustic environment types (i.e., pelagic vs. on‐shelf), 2) evaluate the performance of a combination of AM compared to the signal full frequency spectrum to characterize marine mammals acoustic assemblages (i.e., species richness–SR–and species identity) and 3) estimate the contribution of SR to the local marine acoustic heterogeneity measured by single AM. We used 23 different AM to develop a supervised machine learning approach to discriminate between acoustic environments. AM performance was similar to the full spectrum, achieving correct classifications for SR levels of 58% and 92% for pelagic and on‐shelf sites respectively and > 88% for species identities. Our analyses show that a combination of AM is a promising approach to characterize marine acoustic communities. It allows an intuitive ecological interpretation of passive acoustic data, which in the light of ongoing environmental changes, supports the holistic approach needed to detect and understand trends in species diversity, acoustic communities and underwater habitat quality. [ABSTRACT FROM AUTHOR]

Sounds are more easily transmitted underwater than through air and many freshwater fish species can hear them, particularly over the low frequencies. Recent studies on freshwater fish evidenced that hearing sensitivities can be limited by the level of ambient noise, a phenomenon also known as acoustic masking. However, it is still unclear whether variations in ambient noises, such as those produced by human activities, may alter fish trophic interactions.The general objective of this study was to propose and evaluate a theoretical framework explicitly linking fish attack rates to species hearing sensitivities and ambient noise levels in freshwater ecosystems. The proposed model shows that the feeding activity of fish at an intermediate position in the food web is conditional on the probability of being acoustically detected by their predators, or of encountering an acoustically distressed resource.Model simulations and preliminary field results suggest that yellow perch (Perca flavescens) could feed more actively in the presence of augmented ambient noise levels. Yellow perch captures per unit effort were higher by a factor of 2.7 in noisy versus quiet days. We argue that fish exposed to intermediate levels of noise could maximise the probability of detecting food patches while minimising their predation risk.Acoustic monitoring programmes for freshwater ecosystems require a fundamental knowledge of underwater noise levels, species hearing sensitivities and features affecting sound propagation. The approach proposed in this paper is seminal in linking the above descriptors in a coherent mathematical framework to understand the effect of underwater sounds on trophic interactions. Such framework is needed to make testable predictions and generalise to other taxa and ecological contexts. [ABSTRACT FROM AUTHOR]