Control of Quagga Mussels with Potash: Trials of Efficacy in Different Source Waters

We conducted studies of acute and chronic toxicity of KCl to dreissenid mussels in water sources from several locations (ground water, Snake River, ID, Lake Ontario, Ontario, and the Colorado River). We found short term exposure of veligers to 960 mg/L KCl produced rapid mortality in water from 3 locations, but veligers in Colorado River water were resistant. In separate tests, we explored the sensitivity of byssal stage mussels in chronic exposures (>29 d) at concentrations of 100 and 200 mg/L KCl. Significant and rapid mortality occurred within 10 d of exposure to concentrations of 200 mg/L KCl, regardless of water source. Mean survival of byssal mussels in 100 mg/L KCl in water from Idaho and Lake Ontario was 4.9 and 6.9 d, respectively; however mean survival in the Colorado River water was > 23 d. We hypothesized sodium concentrations may affect mussel survival. To test our hypothesis, we supplemented Snake River and Lake Ontario water with NaCl to equivalent conductivity as the Colorado River, and found mussel survival increased to levels observed in tests of veliger and byssal mussels in Colorado River water. We recommend KCl disinfection and eradication protocols be developed to consider water quality characteristics of locations.