Assessing the toxicity of sodium chloride to the glochidia of freshwater mussels: Implications for salinization of surface waters

摘要

Chloride concentrations in surface waters have increased significantly, a rise attributed to road salt use. In Canada, this may be a concern for endangered freshwater mussels, many with ranges limited to southern Ontario, Canada's most road-dense region. The acute toxicity of NaCl was determined for glochidia, the mussel's larval stage. The 24 h EC50s of four (including two Canadian endangered) species ranged from 113-1430 mgCll~(-1) (reconstituted water, 100 mg CaCOal~(-1)). To determine how mussels would respond to a chloride pulse, natural river water (hardness 278-322 mg CaCo_3L~(-1)) was augmented with salt. Lampsilis fasciola glochidia were significantly less sensitive to salt in natural water (EC50s 1265-1559 mg Cl L~(-1)) than in reconstituted water (EC50 285 mgL~(-1) ). Chloride data from mussel habitats revealed chloride reaches levels acutely toxic to glochidia (1300 mgL~(-1)). The increased salinization of freshwater could negatively impact freshwater mussels, including numerous species at risk.