Temperature effects on burrowing behaviors and performance in a freshwater mussel

Despite the limited mobility of freshwater mussels, locomotion, especially burrowing, may be a critical part of their ecology. The effects of temperature on burrowing activities in freshwater mussels have not received much attention. In the laboratory, we studied the effects of three temperatures (ca. 10, 20, and 30°C) on mussel burrowing behaviors and performance. Behaviors assessed include latency to valve opening, latency until the foot becomes extended, and latency until burrowing. We also quantified burrowing performance by measuring burrowing duration. Mussels were significantly more likely to extend their foot and ultimately burrow at the highest experimental temperature. Burrowing performance was not significantly impacted, with burrowing duration being largely unaffected by temperature. This pattern suggests a hypothetical mechanism, whereby if some temperature threshold is reached that allows burrowing, the animal burrows normally. If that threshold is not attained, the mussel will not explore its environment nor burrow. The implications of this work are important to mussel biology and conservation because the thermal regimes of aquatic systems are changing with other global temperatures and smaller-scale effects are common, such as alteration of thermal regimes due to the outflow from dams. If mussels in these systems are affected they are likely, in turn, to affect community and ecosystem ecology in their native habitats.