Survival and behaviour of juvenile unionid mussels exposed to thermal stress and dewatering in the presence of a sediment temperature gradient

Summary Freshwater mussels (Unionidae) are a highly imperilled faunal group. One critical threat is thermal sensitivity, because global climate change and other anthropogenic activities contribute to increasing stream temperature and altered hydrologic flow that may be detrimental to freshwater mussels. We incorporated four benthic environmental components – temperature, sediment, water level (a surrogate for flow) and a vertical thermal gradient in the sediment column – in laboratory mesocosm experiments with juveniles of two species of freshwater mussels (Lampsilis abrupta and Lampsilis radiata) and tested their effects on survival, burrowing behaviour and byssus production. Increasing temperature diminished burrowing behaviour significantly in both species (P