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Résumé :
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In order for an acoustic signal to be an effective source of communication, the signal must be successfully detected and interpreted by the intended receiver. One potential barrier to acoustic communication is background noise. Lotic systems contain a wide variety of habitats including riffles, shoals and waterfalls that can become quite noisy. The increasing prevalence of road and train crossings over small streams, and increased boat traffic in navigable rivers and lentic systems also presents potential anthropogenic noise sources with which vocal fishes did not evolve. The present study investigates the relationship between vocalizations and the natural soundscape of a common fish of the Southeastern United States, the Blacktail Shiner (Cyprinella venusta), and the potential effects anthropogenic noise from bridge crossings may have on the soundscape and acoustic communication in this species. Results revealed a particularly close association of a quiet window in the natural soundscape of C. venusta and dominant frequencies of the courtship vocalization of C. venusta. Results also indicated that C. venusta's acoustic signals propagate short distances, following predictions based on the calculated cutoff frequency of the streams they inhabit, and were masked by noise generated from bridge crossings. Our calculations suggest that road traffic noise propagates to an extent that virtually entire watersheds are impacted by this noise pollution, especially in urban areas. (C) 2015 Elsevier Ltd. All rights reserved.
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