Experimental sound exposure modifies swimming activities and increases food handling error in zebrafish (Danio rerio)

Anthropogenic noise is increasing globally and is recognized as a source of environmental pollution in terrestrial and aquatic habitats. Sound is an important sensory stimulus for aquatic organisms and it may alter stress-related physiological indices and induce broad behavioural effects in a range of marine and freshwater fishes. Specifically, sound exposure may induce changes in swimming activities, feed efficiency and spatial distribution changes in fish. Here, we experimentally tested sound effects on swimming activities and foraging performance in thirty individually housed, captive adult Zebrafish (Danio rerio). Adult zebrafish and water fleas (Daphnia magna) were used as model predator and prey species, respectively. Acoustic stimuli consisted of four sound treatments with different temporal patterns. All had the same frequency range and were administered on average 121 dB re 1 {micro}Pa2/Hz. Our results constitute strong evidence for sound-related effects on zebrafish behaviour. All sound treatments led to a significant increase in the number of startle responses, and the brief and prolonged swimming speed for zebrafish. We found sound effects on the spatial distribution of zebrafish; Although there were no significant sound-related changes for horizontal spatial displacement in all treatments, zebrafish swam significantly more in the lower layer of the tank except during the irregular intermittent 1:1-7 in brief sound exposure treatment. The results of foraging performance showed that food discrimination error was unaffected by sound treatments and was low for the zebrafish. However, food handling error was affected by sound treatments; all treatments induced a significant rise in handling error. This study highlights the impact of sound on zebrafish swimming activities, and that more feeding bouts are needed to consume the same number of food items increasing energy demand under noisy conditions.