LAUSR

The Daphnia magna Straus (1820) crustaceans are used in many countries to assess the quality of the environment. Researchers are guided more often by the mortality of individuals. However, the sublethal effects contribute to the development of biological early warning systems (BEWS). A visual method for recording the motor activity of D. magna was proposed. This method has advantages over automated analogs. It is simple, accessible to performers and does not require the use of special instruments. The method was tested under conditions of modeling the lethal and sublethal effects of heavy metal salts (Cu and Zn). The diagnosis of lethal doses is possible after 1 hour of exposure, whereas the death of crustaceans can occur in 3–4 days of the experiment. The effect of sublethal doses of heavy metals becomes statistically significant after 24 (p <0.05). The sensitivity of the method was confirmed in the studies of the aqueous extracts from the soils contaminated with various heavy metals (heavy metal processing area). The method showed good results in assessing the toxic effect of the waters anthropogenically contaminated with the mineral forms of nitrogen (NH4 +and NO3 -) in the region of fertilizer production. The maximum inverse correlation between the motor activity and the concentration of ammonium ions in water (-0.83) was shown after 24 hours. Thus, the method of visual assessment of motor activity can be used in environmental monitoring.