Threshold Concentrations of Cations in the Water Necessary for Maintaining the Ionic Balance Between Organism of Chironomus balatonicus Devai et al. Larvae and Environment

Threshold concentrations of sodium, potassium, calcium, and magnesium in water determining the borders of the Chironomus balatonicus range in waterbodies are 0.6–0.62, 0.11–0.12, 0.071–0.073, and 0.022–0.028 mmol/L, respectively. In the freshwater section of the Curonian Lagoon of the Baltic Sea and other waterbodies with weakly mineralized water where the content of ions is lower than the threshold values, larval Ch. balatonicus cannot dwell because of the impossibility of maintaining the ionic balance between the organism and environment. The threshold concentrations and rates of loss of ions from an organism in various species of aquatic organisms are comparatively analyzed.