Biological responses to high-frequency sound in a freshwater crayfish, Cherax quadricarinatus

Anthropogenic noise is recognised as an important environmental stressor that can have longterm negative consequences on species. In recent years, there has been increasing attention to the potential negative impact of noise pollution on species, with great concern for the importance of impacts on aquatic animal life. This study examined the effects of acoustic stress on the biochemical parameters of the freshwater crayfish Cherax quadricarinatus. The experiment was conducted in a tank equipped with an audio and video recording system using ten groups (five control and five test) of three adult crayfish (30 animals in total). The animals in the test group were exposed to acoustic signals [a linear sweep from 10 to 200 kHz lasting 1 s, with a sound pressure level between 138 and 157 dBrms (re 1lParms)] for 45 minutes. Biochemical parameters such as pH, osmolarity, protein concentration and enzyme activities (alkaline phosphatase, esterase and peroxidase) were evaluated. Enzyme activities show significant changes, with significantly lower values in stressed animals. These results suggest that high-frequency stimuli induce a physiological stress response, thus suggesting that acoustic stress may have physiological effects on the species.