LAUSR

We examined the physiological rates of 2 freshwater mussel species, Lampsilis cardium and Amblema plicata, as they experienced rising temperatures in a controlled laboratory setting. We chose these species because they have a widespread distribution, are common throughout North America, and vary in thermal tolerance. We varied the density and species composition of mussels in tanks. We measured algal clearance rate, oxygen consumption, biodeposition, and changes in nutrient concentration as mussels were exposed to incrementally-increasing temperatures relevant to regional climate projections. We found that these species have distinct physiological responses to increasing temperatures. The mass-specific physiological rates of L. cardium changed more than those of A. plicata when exposed to rising temperatures. Additionally, our findings suggest that mussel response to rising temperatures may vary as a result of mussel assemblage, density, and species composition. Thus, negative impacts of warming stream temperatures on freshwater mussels have the potential to affect the entire ecosystem. Understanding how freshwater mussel species may respond to climate change will help us better manage mussel communities and aquatic ecosystems.