Spring zooplankton communities of ponds in Zarechny (Penza region)

Background. City ponds experience a huge recreational load, without receiving proper care. Zooplankton communities are good indicators of the state of the hydroecosystem. The purpose of the research is to study the features of the species and spatial structure of spring zooplankton communities, to assess the trophic status and sanitary condition of the ponds of Zarechny. Material and methods. Samples for zooplankton research were collected in April 2024 from city ponds in Zarechny (Penza region). A total of 19 samples were analyzed. The collected material was processed using generally accepted methods in hydrobiology. Results. 90 species and subspecies of zooplankton were found (Rotifera – 69, Cladocera – 12, Copepoda – 9). For the first time in Penza region, two species of rotifers were noted (Cephalodella auriculata and Trichocerca bicristata). A high proportion of phytophilic species indicates a significant degree of overgrowing of water bodies with macrophytes and accumulation of organic matter. The ponds require a certain regulation of their state, as indicated by the structural parameters of zooplankton communities. In the first and second Lermontov ponds, the bottom is covered with a thick layer of silt, the water is almost not mixed, stagnant processes develop. The species composition of zooplankton communities is small, dominated by only one eutrophic species of copepods. The other two ponds (the third and fourth) and the Lesnoy pond are larger, with open banks, less foliage and silt accumulates in them, and the water mixes in windy weather. Rotifers (the eurybiont Synchaeta pectinata and the cold-loving Polyarthra dolichoptera and Keratella irregularis) are dominant in the reservoirs. Conclusions. High quantitative characteristics of zooplankton communities of ponds in spring can be explained by good warming of water (against the background of unusually warm spring and small sizes of reservoirs) and development of a good food base for zooplankton. Species richness and spatial structure of zooplankton community allow classifying the studied ponds as eutrophic. Recreational pond Lesnoy requires cleaning.