Lethal Levels of Sodium Chloride and Potassium Chloride for an Oligochaete,1 a Chironomid Midge,2 and a Caddisfly3 of Lake Michigan4

Abstract

Three species of aquatic invertebrates, sampled at sites in Lake Michigan, were subjected in the laboratory to known sodium chloride and potassium chloride concentrations in aqueous solutions. Lethal levels for each organism were observed and recorded for periods of 48 h. One hundred percent mortalities for NaCl concentrations were calculated from a regression line to be 3735 mg/liter for Nais variabilis (Piguet), 8865 mg/liter for Cricotopus trifascia Edwards, and 10,136 mg/liter for Hydroptila angusta Ross. KCl concentrations at 204 mg/liter for N. variabilis, 4896 mg/liter for C. trifascia, and 6317 mg/liter for H. angusta were calculated for the 100/ mortality level. The lethal aspects of these chloride salts are discussed.