Аңдатпа
This article investigates the impact of technogenic phosphorus-containing waste on the ecological condition of the aquatic ecosystem of the Lenger River, located in the southern region of Kazakhstan. Water samples were collected in June 2025 from five sites characterized by different levels of anthropogenic load. Laboratory experiments were conducted using river water samples and technogenic waste rock materials with the addition of phosphorus-containing residues at concentrations of 0.1%, 0.3%, 0.5%, and 1.0%; control samples did not contain any additional impurities. Incubation was carried out for 72 hours at a temperature of 22-24°C under natural light conditions. Taxonomic analysis revealed representatives of phytoplankton and protozoa belonging to the divisions Chlorophyta, Euglenophyta, Bacillariophyta, Cyanophyta, and Protozoa. Among green algae, Chlorella vulgaris and Scenedesmus quadricauda predominated; diatoms were represented mainly by Navicula vulpina and Fragillaria austriaca; euglenophytes included Euglena agilis and Phacus brevicaudatus. Samples also contained cyanoprokaryotes (Oscillatoria, Anabaena) and protozoa (Paramecium, Arcella, Euplotes), indicating high trophic status and organic pollution of the water. At concentrations of 0.1-0.3%, active development of Chlorella vulgaris and Scenedesmus quadricauda was observed, whereas at 0.5-1.0% most species exhibited growth inhibition, decreased water transparency, and the formation of organo-mineral sediments. Diatom algae showed the highest sensitivity to phosphate contamination. The obtained results demonstrate that low concentrations of phosphorus-containing wastes enhance the photosynthetic activity of microalgae, indicating their ability to utilize these substances as nutrient sources. However, increasing concentrations to threshold levels lead to destabilization of aquatic communities and degradation of the biocenosis. Thus, the revealed patterns confirm that microalgae and protozoa can be effectively used as reliable bioindicators of anthropogenic impact and ecological status in small river ecosystems of Kazakhstan.