Road Salt Impact on a Stream-Dwelling Salamander, Eurycea bislineata : A Low Threshold for Behavioral and Physiological Effects

Road salt runoff into aquatic habitats is a major ecological issue for amphibian species due to potential toxic effects from chemicals such as hydrocarbons, de-icing agents and salts. Road salt runoff can affect different aspects of amphibian biology, such as osmotic balance, growth, reproduction, behavior, and survival. This study investigated the behavioral and physiological salinity tolerance of adult two-lined salamanders, Eurycea bislineata. Two-lined salamanders are found in small streams and rivulets and may be exposed directly to salt runoff. In laboratory behavior trials, E. bislineata showed strong aversion to increasing salinity concentrations. They spent less time in higher NaCl concentrations and were more likely to conclude a trial on the control side of the test arena, where conditions were less saline. In physiological performance trials, E. bislineata showed reduced stamina (time traveled until exhaustion) and traveled shorter distances as salinity concentrations increased. For both behavioral and physiological trials, negative effects were seen at 0.1 M NaCl and above. Stamina was reduced by 77.5% at this concentration and the EC50 for behavioral aversion was 0.09 M (95% C.I. 0.012-0.143 M). Salinity levels due to road salt runoff have been found to exceed these concentrations, especially in urban and suburban areas and may pose significant risks for this species. Road salt runoff should be managed to stay under this target concentration to reduce the impacts on amphibians