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

Abstract

AbstractAnthropogenic sound is globally increasing 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 cause fluctuations in stress-related physiological indices and in a broader extent induce behavioural effects in a range of marine and freshwater fishes. However sound exposure may also induce changes in swimming activities, feed efficiency and productivity of available food sources in fish. Here, we experimentally tested sound effects on swimming activities and foraging performance in thirty adult Zebrafish (Danio rerio) individually in captivity. We used adult zebrafish and water flea (Daphnia magna) as model predator and prey, respectively. In terms of acoustic stimuli, we used four sound treatments with different temporal patterns (all in the same frequency range and moderate exposure level). 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 response, brief and prolonged swimming speed for zebrafish (P<0.05). We found partially brief and prolonged sound effects on the spatial distribution of zebrafish; Although there were not any significant sound-related changes for horizontal spatial displacement in all treatments (P>0.05), zebrafish swam significantly more in the lower layer of the tank except for irregular intermittent 1:1-7 in brief sound exposure (P<0.05). The results of foraging performance showed that food discrimination error unaffected by sound treatments and was low for the zebrafish (P>0.05). However, food handling error was affected by sound treatments; all treatments induced a significant rise in handling error (P<0.001). 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.