Spatial distribution of zooplankton communities in the littoral zone in small lakes of Nizhny Novgorod Region (European Russia)

Aquatic macrophytes in the littoral zone of lakes act as a powerful environmental factor, shaping the spatial distribution of aquatic organisms. The study examined the distribution patterns of zooplankton communities across the transverse profile of macrophyte beds in the littoral zone of small lakes in the Nizhny Novgorod region. It was found that in the studied biotopes, macrophyte beds altered several water parameters and created their gradient. The analysis revealed that, from the shoreline helophyte and mixed vegetation toward the open water, zooplankton communities exhibited a gradual shift in dominant and subdominant species, a decrease in the proportion of cladocerans, and an increase in rotifers. The type of biotope had the greatest influence on the species structure of zooplankton communities. The study also analyzed the preference of certain zooplankton species for macrophyte beds of different life forms. A decline in species richness and zooplankton biomass was observed at the edge of vegetation near the open water. It was concluded that the succession of plants from different ecological groups along the transverse profile of the macrophyte zone drives changes in environmental factors and planktonic invertebrate communities in an ecocline-like manner.