Abstract
Small lakes remain insufficiently studied in terms of their zooplankton communities, resulting in limited information on their species composition, abundance, biomass, and ecological role. Zooplankton serves as a crucial link between primary producers and higher trophic level consumers, making it a key component for ecological monitoring. In September 2025, hydrobiological investigations were conducted in the lakes Bolekkyzyl, Zhetitobe, Zhailauköl, and Kolme, located in Zhambyl region. Samples were collected using an Apstein plankton net, and analysis revealed the presence of rotifers, cladocerans, copepods, and additional water-column inhabitants. The results demonstrated significant differences in taxonomic composition, abundance, and biomass of zooplankton among the lakes. The highest species diversity was recorded in Zhetitobe, with 11 taxa, while the lowest diversity was observed in Kolme, with 6 taxa. In all lakes, the dominant zooplankton groups were rotifers, cladocerans, and copepods, whereas additional water column inhabitants were present in limited numbers. Dominants varied across lakes: in Zhetitobe, Cyclopoida gen. sp. predominated, accounting for 88% of total abundance and 67% of biomass, with the rotifer Asplanchna sp. contributing up to 20% of the biomass. In Zhailaukоl, Cyclopoida gen. sp. also dominated both numerically (75%) and in biomass (83%). In Bolekkyzyl, copepods (Cyclopoida gen. sp.) formed the main component of the community, while Asplanchna sp. contributed up to 20% to the total biomass. In Kolme, cladocerans Diaphanosoma lacustris were dominant, with comprising approximately half of both abundance and biomass, while among copepods, Arctodiaptomus salinus accounted for up to 25% of the total abundance. These findings provide a clear illustration of the structural characteristics of the aquatic ecosystems in different lakes. The low biomass values indicate that the studied water bodies belong to α–β-oligotrophic types, characterized by low productivity. The obtained data provide a reliable foundation for evaluation of local biodiversity and analysis of anthropogenic impacts.