Ecological Systems and Devices Annotation << Back The Effect of Plastic Nanoparticles on the Representatives of Phyto- and Zooplankton Lazareva A.M., Rak A.N., Ipatova V.I., Gershkovich D.M., Ilinskiy V.V., Il’ina O.V., Poyarkov A.A. The toxic effect of primary polystyrene nanoparticles (PS-NPs) with a particle size of 100 nm on the structural and functional parameters of the development of the freshwater microalga Scenedesmus quadricauda at concentrations of 1, 5, 10 and 50 mg/l and on the survival, fertility and linear sizes of the freshwater crustacean Daphnia magna was studied at concentrations of 0.3; 1.0 and 3.0 mg/l in chronic tests lasting 14 and 21 days, respectively. The toxicity of PS-NPs depended on the concentration, exposure time, and test parameter assessed. Using different structural and functional indicators of the state of the S. quadricauda population, an ambiguous mosaic response of the test culture to the presence of PS-NPs in the culture medium in the range of studied concentrations was discovered. General biological integral indicators of cell number and population survival (proportion of living cells), as well as such structural indicators as cell size and number of cells in coenobium, changed asynchronously with each other, as well as with the physiological indicator (photosynthetic effi ciency). In terms of the number of microalgae cells, PS-NPs are 3 orders of magnitude more toxic than polystyrene microplastic particles. An increase in the proportion of coenobia with an atypical number of cells and an increase in cell size during intoxication were shown. PS-NPs did not have a signifi cant effect on the survival of D. magna, however, a decrease in the average linear size of individuals and a signifi cant decrease in the average total fertility of individuals per female was noted, which indicates a considerable infl uence of PS-NPs on this test object at the embryonic stage of its development. Keywords: polystyrene nanoparticles, Scenedesmus quadricauda, Daphnia magna, toxicity, bioassay. DOI: 10.25791/esip.11.2023.1413 Pp. 45-56.