Seasonal succession of zooplankton communities in macrophyte thickets of a small river (on the example of the Levinka river, Nizhny Novgorod)

Seasonal succession of zooplankton communities in macrophyte thickets of small rivers is still poorly studied. In this paper we characterize seasonal succession as a change in the species structure of zooplankton communities of different types of macrophyte thickets of the small river Levinka (Nizhny Novgorod) and analyze the influence of environmental factors on it. On the basis of hierarchical clustering, planktonic complexes were identified in the studied biotopes. Differences in the structure of planktonic complexes in different types of macrophyte thickets were shown. In thickets of submerged macrophytes, the most long-lived planktonic complexes were formed. In thickets of plants of the same ecological group, zooplankton complexes with Sida crystallina dominance were similar in species structure during the summer season. The most significant changes in the species structure of zooplankton communities in thickets occurred in June and October. The cyclic character of seasonal succession of zooplankton communities in macrophyte thickets was revealed. Water temperature and projective cover of macrophytes had the greatest influence on the course of seasonal succession. It was shown for the first time that the alien rotifer Kellicottia bostoniensis (Rousselet, 1908) reached mass development in macrophyte thickets during the period of plant die-off. It was revealed that the Shannon species diversity index reflects the restructuring of the species structure of zooplankton communities in macrophyte thickets of a small river.