Toxicity of various road-deicing salts to Asian clams (Corbicula fluminea).
Humans are altering environments by destroying habitats, introducing species, and releasing pollution. One emergent pollutant is the salinization of freshwater habitats from road-deicing salts. Government agencies have set thresholds to protect freshwater ecosystems, yet these values are exceeded in many systems. The present study investigated the tolerance of Asian clams (Corbicula fluminea), a common invasive bivalve, to the common road salt (sodium chloride [NaCl]) and 2 alternatives (magnesium chloride [MgCl2] and calcium chloride [CaCl2]). Experiments conducted at 4 and 8 d revealed that Asian clams are very salt tolerant. The median lethal concentration after 4 d of exposure (LC504-d) estimate was 2162 mg Cl-/L for MgCl2, 3554 mg Cl-/L for CaCl2, and more than 22 581 mg Cl-/L for NaCl, which were all significantly different from each other (p≤0.05). The LC508-d values were significantly different (p≤0.05) from each other and from the LC504-d values, and were estimated to be 1769 mg Cl-/L for MgCl2, 2235 Cl-/L for CaCl2, and 10 069 mg Cl-/L for NaCl. Mortality was determined using 2 methods: either no response after exposure or no response after being in freshwater following exposure. For the majority of the LC50s, these methods were not significantly different (p>0.05). The high salt tolerance of Asian clams is a concern because of their transportation in ballast water between aquatic ecosystems. Furthermore, salt-tolerant organisms may outcompete sensitive organisms in salinized ecosystems, which may alter ecosystem services.