The data obtained show that at low concentrations (0.01 mg dm -3 and 0.1 mg dm -3 ), 1Asp did not affect the reproduction of D. magna females, and the number of parthenogenetic offspring did not differ significantly from control organisms. At a concentration of 1 mg dm -3 , the applied QAS caused a reduction in the number of offspring by an average of 48% as well as other adverse effects (occurrence of aborted eggs and dead neonates), indicating the presence of toxic effects.