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

Anthropogenic sound is currently recognized as a source of environmental pollution in terrestrial and aquatic habitats. Elevated sound levels may cause a broad range of impacts on aquatic organisms among taxa. 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 such as driving as a distracting stimulus, masking important relevant acoustic signals and cues in a range of marine and freshwater species. 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 prey, respectively. We also used four sound treatments with different temporal patterns (all in the same frequency range and moderate exposure level). Our results constitute strong evidence for clear sound-related effects on zebrafish behaviour. All sound treatments induced a significant increase in the number of startle response, brief and prolonged swimming speed for zebrafish (P<0.05). Zebrafish reached to the baseline swimming speed after 60 seconds in all treatments. We found partially brief and prolonged sound effects on spatial distribution of zebrafish; Although we did not find any significant sound-related behavioural changes for horizontal spatial displacement in all treatments (P>0.05), zebrafish swam significantly more in the lower layer of the fish tank except irregular intermittent 1:1-7 in brief sound exposure (P<0.05). The results of foraging performance showed that food discrimination error was low for the zebrafish and unaffected by sound treatments (P>0.05). However, food handling error was affected by sound treatments; all treatments caused a rise in handling error (P<0.001). This study highlights the impact of sound on zebrafish swimming activities, and that more attacks are needed to consume the same number of prey items under noisy conditions.