Macrozoobenthos of Communities of Higher Aquatic Vegetation

Abstract

This article presents the results of a comprehensive study of two components of the aquatic biocenosis: its floristic component and benthos in the shallow waters of the Gorky Reservoir within the water area of the Yaroslavl State Nature Reserve. The composition and structure of plant communities at the boundary of the macrophyte belt is assessed, followed by the identification of dominant associations. At the same time, the taxonomic composition and quantitative characteristics of macrozoobenthos are assessed in the main plant biotopes. Plant communities in the water area are represented by two ecological groups: helophytes and hydrophytes. Macrophytes occupy up to 25% of the water area of the shallow area of the studied water body. Most of the plant communities are concentrated in the northern and northeastern parts of the reserve. Eleven species of macrophytes belonging to 10 genera and 9 families are noted. In macrophyte communities, eight typical associations were identified where benthos sampling are carried out. In the benthos of typical macrophyte associations, 35 lower definable taxa (LDT) are identified, of which 17 LDT are chironomid larvae. In the biotope, 11 LDT are found out of vegetation. The highest species richness of benthic invertebrates is noted in the communities of Butomus umbellatus L. (1753) and Sparganium erectum L. The benthos of plant communities in August 2021 can be characterized as chironomid–oligochaete, while chironomids dominate in the open littoral. Mollusks play a significant role in the formation of benthos in plant communities. The maximum quantitative indicators of benthic invertebrates in general—and the abundance of chironomids of the genus Glyptotendipes, in particular—have been noted in the community of the burr Sparganium erectum. This is probably due to the morphological structure of this plant and the specifics of the formation of the community by this species. The benthos of plant communities is dominated by phytodetritophages–filterers and phytodetritophages–filterers + gatherers, while phytodetritophages–filterers prevail in the open littoral. There are no detritophages–gatherers in any of the studied biotopes. In general, according to the abundance of macrozoobenthos, the areas of plant communities can be classified as high-nutrient and very high-nutrient.