The effect of seismic air gun shots on physiology and behaviour of fish lake communities.

Alterations in the acoustic environment owing to anthropogenic sound are recognised as global pollution and strengthening studies in freshwater. This study focuses on the impact of lake seismic surveys on fish. First, we measured individual stress responses, i.e. cortisol levels and oxidative stress, morphological parameters, and stomach contents of juvenile roaches (Rutilus rutilus) captured by trawling prior to and during the seismic survey. Second, using hydroacoustics, we analysed individual fish and school behaviour before, during, and after the shots. We collected environmental DNA (eDNA) and analysed the concentrations of three species to assess their littoral refuge. Finally, using hydroacoustics, we assessed pelagic fish density before, during, and after the shots. We demonstrated that the shots noticeably impacted juvenile roaches, from the molecular and cellular level to individual morphological characteristics. During the seismic shots, changes in school characteristics were observed. At the onset of the seismic survey, a sharp decrease (> 30%) in pelagic fish density was observed, and no increase in fish density in the littoral area was noted for the three species. These responses suggest that sound disturbances due to air gun shots affect fish in multiple ways (physiology, morphology, behaviour, and habitat use) and across multiple biological scales.