Establishing mussel behaviour as a monitoring tool to measure climatic disturbances

Freshwater mussels (FM) are suitable biological indicators to assess environmental stressors. Behaviour is a good parameter to measure rapid mussel’s responses. In this sense, valvometric method, that exploits the Hall sensor (real-time remote monitoring tool), has been used to measure the behavioural responses of mussels (valve opening amplitude and valve opening-closure frequency). During the last two decades, these methodologies have been used to measure the presence of the pollutants in the waterbodies. However, studies that focus on physical disturbances in the environment related to climate changes are lacking. Since future climatic scenarios in Europe predict an increase in temperature and change in the hydrological conditions, the main objective of this study was to evaluate the influence of water temperature increase and water discharge rates (without and with sediment transport) in four endpoints of mussel's behaviour: normal activity, resting, transition and avoidance. Our results suggest, that on experiments with increasing temperatures and high variation in water discharge rates with sediment transport, mussels presented high valve opening-closure frequencies and amplitudes. In this sense, mussels could be used as biological sensors to monitor changes in thermal and hydrological conditions which are increasing with climate changes.