Threshold environmental concentrations of cations defining the range of roach Rutilus rutilus L. in freshwater reservoirs

Abstract

Threshold levels of sodium, potassium, calcium, and magnesium that define the distribution range of roach in fresh water are 0.015-0.019, 0.012-0.015, 0.006-0.009, and 0.002-0.003 mmol/L, respec tively. A reduction in water mineralization is accompanied by a significant decrease in the concentration gra dient of cations between the organism of a fish and the environment and by the increased stress on the systems responsible for salty exchange. Many reservoirs are characterized by lower concentrations of potassium in the water than is needed for the success of the roach population. The survival of roach in these waterbodies depends on the amount of potassium consumed by fish with their food. A comparative analysis is performed to assess the threshold levels of cations for roach, two bivalve mollusk species, crayfish, and the filamentous algae Spirogyra.

In-situ sampling of available calcium using diffusive gradients in thin-films technique based on benzo-crown ether-functionalised silica as the binding agent

“…This is an important limiting factor for the measurement of analytes by DGT in the environment (Zhang et al 2014). Threshold levels of total Ca 2þ in freshwaters can range from 240 to 360 mg L À1 (Martemyanov and Mavrin 2012). In order to assess the saturation adsorption capacity of BCES gel discs, the initial concentrations of free Ca 2þ in the feed solution were selected in the range of 100-500 mg L À1 (Fig.…”