title: Assessing the toxicity of sodium chloride to the glochidia of freshwater mussels: implications for salinization of surface waters.
abstract: 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 24h EC50s of four (including two Canadian endangered) species ranged from 113-1430 mg Cl L⁻¹ (reconstituted water, 100 mg CaCO₃ L⁻¹). To determine how mussels would respond to a chloride pulse, natural river water (hardness 278-322 mg CaCO₃ L⁻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 mg L⁻¹). Chloride data from mussel habitats revealed chloride reaches levels acutely toxic to glochidia (1300 mg L⁻¹). The increased salinization of freshwater could negatively impact freshwater mussels, including numerous species at risk.
authors.affiliation: National Water Research Institute, Environment Canada, Burlington, ON L7R-4A6, Canada. patty.gillis@ec.gc.ca
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Gillis
mesh_terms: D000818:Animals; D002712:Chlorides / Q000032:analysis / Q000633:toxicity; D005618:Fresh Water / Q000737:chemistry*; D007814:Larva / Q000187:drug effects / Q000378:metabolism; D009864:Ontario; D054712:Salinity; D012965:Sodium Chloride / Q000032:analysis / Q000633:toxicity*; D049876:Unionidae / Q000187:drug effects* / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
chemical_list: D002712:Chlorides; D014874:Water Pollutants, Chemical; D012965:Sodium Chloride