The Effects of Increased Salinization On Gene Expression in the Freshwater Eastern Elliptio Mussel

Chloride concentrations have increased in freshwater ecosystems in the northeastern United States and further salinization may occur due to anthropogenic activity including development, road de-icing, and brines released from fossil fuel extraction techniques.  Potential sublethal effects of acute and chronic salinity exposure on the freshwater Eastern elliptio mussel (Elliptio complanata) are not well understood.  Eastern elliptio mussels were exposed to four salt concentrations (0, 2, 4, and 6 ppt sodium chloride) for seven days to determine the lethal concentration.  Using transcriptome analyses, differentially expressed genes were identified in mussels from the 2 ppt treatment group.  Expression of potential stressor-specific molecular biomarkers were then assessed in freshwater mussels exposed to three salt concentrations (0, 1, 2 ppt sodium chloride) at three time points (24 hours, 7 days, 4 weeks).  These studies will improve understanding of the physiological and molecular effects of salt exposure in freshwater mussels and will help develop meaningful biomarkers for nonlethal field monitoring of rare or declining freshwater mussel populations.