Noise pollution is a serious problem that has increased dramatically with recent human development. Despite their seemingly quiet underwater habitat, freshwater fishes are not sheltered from elevated noise levels. Bridge and boat traffic, along with natural noise sources including other organisms, waterfalls, rainfall, and water turbulence all contribute to a noisy aquatic environment. Higher noise levels can result in elevated hearing thresholds of hearing specialists, and decrease the signal-to-noise ratio of acoustic signals. Because many fishes use acoustic signals during critical life history stages (such as reproduction and territory defence), it is important to determine whether elevated noise levels affect behaviour during these stages. The objectives of this study were to determine the effect of elevated noise levels on nest choice, acoustic communication, and reproductive and aggressive behaviours in the black tail shiner, Cyprinella venusta. To determine how noise affected nest choice, two underwater speakers were suspended over artificial crevice nests on opposite sides of a 1022 l tank. Bank limited white noise was played from one speaker, while the other speaker remained silent. The amount of time spent, and number of aggressive and reproductive behaviours performed by males at the quiet nest was then compared to the noisy nest. To determine how elevated noise affected acoustic communication, trials during which the sounds and associated behaviours of C. venusta were recorded were performed in two tanks: one with elevated noise, and one with silence. Acoustical parameters that were compared included amplitude, frequency, call duration, and call frequency. Behavioural parameters compared included distance between sender and receiver, and the number, duration, and escalation of aggressive and reproductive behaviours.
Abstract: