Vol 12, No Suppl 2 (2019)

Excavated ponds are a group of widely distributed small artificial water bodies in the territory of Central Russia. In the countryside, they play an important role as water storage for the irrigation of vegetable gardens, livestock watering, the cultivation of waterfowl, and fire water ponds. In 1998–2014, 49 village excavated ponds located in the northwestern part of Yaroslavl oblast were studied. The inventory of the flora of village ponds revealed 161 species of vascular plants from 44 plant families and 88 genera. The dominant plant families in the flora of such water bodies are Poaceae, Cyperaceae, Asteraceae, Polygonaceae, and Salicaceae; the dominant genera are Carex, Salix, Bidens. The ecotypes of hygrophytes and hygromeso- and mesophytes prevail in the ecological structure of the studied flora. Boreal and plurizonal species are dominant in the geographical structure, and Holarctic and Eurasian species prevail in the regional one. The abundance of plurizonal species among typically aquatic vascular plants, due to a relatively high consistency of the aquatic environment when compared to terrestrial ecosystems, makes flora of village ponds similar to that of other water bodies in the studied area. At the same time, the results of long-term studies make it possible to distinguish such features of flora of these small artificial reservoirs as a large number of occasional plant species not typical for water bodies and extremely high dynamics of their flora in different growing seasons.

The structural parameters of phytoplankton in the estuarine region of a small tributary (Ild River) were studied in 2009–2011 and compared with the adjacent sections of the free-flowing section of the river and the pelagic zone of the Rybinsk Reservoir. Phytoplankton of the mouth estuarine region of the Ild River is characterized by high floristic and specific richness, biomass and coenotic diversity. With an increase in water temperature and a decrease in the water level in the reservoir, an increase in floristic richness, biomass, and the degree of similarity of the ratio of large taxonomic groups of algal communities of ecotone and border zones were observed in the mouth area of the tributary.

This study presents data on actual seed productivity and the ability to spread generative diaporas of various Sparganium species. It is established that, by decreasing the actual seed-productivity index, Sparganium species are arranged in the following order: S. microcarpum (Neum.) Domin. > S. emersum Rehm. > S. glomeratum (Laest.) Neum. > S. gramineum Georgi. > S. erectum L. > S. hyperboreum Laest. ex Beurl. > S. natans L. The lowest actual seed-productivity indices are recorded in representatives of the Minima section—S. hyperboreum and S. natans, which is caused by the miniaturization of the sizes of these species. Investigations into the floating ability of the fruitlet show that the representatives of the subgenus Sparganium (compared to the representatives of the subgenus Xanthosparganium) have higher buoyancy, which is associated with the higher wall thickness of the stone fruit and the number of air cavities in the pericarp. Unlike other species, the fruitlet of S. gramineum sinks to the bottom of the reservoir after separation from the plant.

An analysis of the results of long-term observations has demonstrated changes in the species structure and a significant increase in the abundance of macrozoobenthos in the deepwater part of the Rybinsk Reservoir in extremely warm years at the beginning of 21st century. After the anomalously hot summer of 2010, the species richness and diversity decreased to their minimum values. In the following years, a peak in the abundance and biomass of macrozoobenthos, due to the mass development of chironomid larvae (g. Chironomus) and polysaprobic species of oligochaetes, has been observed. Presumably, this peak is determined by the increased rates of eutrophication.

In various biotopic groups of invertebrates of small rivers, the species richness and nematode abundance vary. Periphyton is poorer than meiobenthos. Along with common species, a number of worms are found only in biofouling or only in meiobenthos. A significant increase in species richness, diversity of ecological groups, and abundance of worms in meiobenthos and periphyton of small rivers is observed in zones contaminated with organic substances of anthropogenic and zoogenic origin. The biocenotic and functional role of nematodes in these groups depends to a higher extent on the level of food availability than on a number of other environmental factors that limit their development.

The aim of this study was to investigate biomarkers of oxidative stress: сatalase (CAT), glutathione (GR), glutathione S-transferase (GST), low-molecular antioxidant—reduced glutathione (GSH) and lipid peroxide oxidation marker—malondialdehyde (MDA) and to measure heavy metal (НМ) concentrations in Dreissena polymorpha soft tissues at three different sampling sites in the Rybinsk reservoir (one of the largest in Europe) in order to assess exposure to anthropogenic pollution. The reservoir has a considerable source of pollution in its northern part due to a large industrial complex in Cherepovets. Mussels were collected at three sites which differ in the levels of anthropogenic load: more contaminated sites 1 (Cherepovets) and 2 (Koprino). Site 3 (Vesyegonsk) is relatively clean and is used as a control. In soft tissues of mussels from sites 1 and 2 significantly higher concentrations of HM (Pb, V, Cr, Ni, Cu, Mn, Zn, Cd) were detected than in mussels from site 3. Mussels from sites 1 and 2 subjected to long-term contamination from Cherepovets industry showed considerable CAT, MDA and GSH induction compared to mussels from relatively clean site 3. The correlation was found between elevated HM content and increased levels of CAT, MDA and GSH. The obtained data suggest that HM may contribute to the oxidative stress induction in mussel. MDA, CAT and GSH sensitivity in D. polymorpha demonstrated a possible use of these biomarkers in freshwater.

We present the results of a comprehensive study of five saline rivers in the arid region of Lake Elton, including hydrobiological surveys of plankton and benthic communities. The DIABLO method was used for a statistical analysis of the associative links between the species structures of the macrozoobenthos, meiobenthos, and zooplankton communities. This method combines multidimensional ordinations based on n blocks of observations and uses special algorithms of canonical correlation. It is shown that a significant portion of the cumulative variation in the data can be explained by a consensus configuration based on information common for all the three groups of observations. The diagrams, constructed and analyzed with the use of the cluster and Generalized Procrustes analysis, enable us to isolate stable associations of taxa typical for particular biotopes with homogeneous environmental conditions. We have constructed graphs of correlation pleiades and calculated indicator significance for particular species of macrozoobenthos, meiobenthos, and zooplankton. It is shown that highly mineralized systems of arid regions are not always characterized by a pronounced specification of life forms of plankton and benthic communities. The interpenetration between benthic and plankton animals results in a high portion of mixed ecological groups. Plankton and benthic communities correlate well enough with each other, which testifies to a close relationship between them due to both biotic interactions and a mutually agreed response to changes in aquatic environment factors. These data enable us to consider the plankton and benthic communities of highly mineralized rivers a nonequilibrium dynamically changing consortia of species.

Chromosomal polymorphism is investigated in samples of Chironomus plumosus L., (1758) (Diptera, Chironomidae) from a pond on the Chemoshur creek in Udmurtia for the first time. The pool of polytene chromosome banding sequences of this species includes 12 banding sequences forming 17 zygotic combinations. The pluF2 sequence is found with a high frequency of 0.17. The cytogenetic distance between the known populations is determined.