Determining the Physiological and Behavioral Responses to Elevated Salinity in the Freshwater Bivalves, Corbicula fluminea and Lampsilis ovata

Salinization has been identified as an increasing threat to freshwater mussel diversity in recent years. Native mussels have been observed to display reduced salinity tolerance in comparison to some invasive bivalve species, but methods by which organismal tolerance is achieved are not well understood. This study was designed to compare the behavioral and physiological responses of the native Lampsilis ovata to that of the invasive Corbicula fluminea. Lampsilis were found to exhibit strong behavioral avoidance to salinity exposure, whereas Corbicula displayed very weak avoidance to comparable salinity concentrations followed by indications of osmotic conformation through physiological mechanisms. Prolonged valve closure in Lampsilis could translate to adverse consequences related to feeding, waste removal, and energetics. Alternatively, while physiological osmotic conformation in Corbicula is associated with increased energetic costs, it allows continued respiration and feeding. These differences could convey a competitive advantage with the increasing prevalence and severity of freshwater salinization events.