Ecology and metabolic activity of cyanobacteria in large different types of lowland reservoirs in the European part of Russia

A comparative of the species composition and ecological-geographical characteristics of cyanobacteria plankton of 13 reservoirs of the Volga-Kama cascade and the Don (Sheksna, Ivankovo, Uglich, Rybinsk, Gorky, Cheboksary, Kuibyshev, Saratov, Volgograd, Kama, Votkinsk, Nizhnekamsk and Tsimlyansk reservoirs) is analysed. An assessment of the change in the distribution of cyanobacteria biomass in a latitudinal gradient along the Volga cascade is presented. The seasonal and long-term (1954–2016) dynamics of the abundance, biomass and the ratio of functional groups of cyanobacteria in the Rybinsk Reservoir, the second largest in the cascade of Volga reservoirs, are analyzed. A positive long-term trend of abundance and diversity of cyanobacteria and the leveling of their biomass between reservoirs along a cascade in recent years has been established. An increase in the abundance and diversity of nonheterocystous species was established in the direction from the Upper to the Lower Volga and during the long-term succession of phytoplankton of the Rybinsk Reservoir. This is associated with an increase of water mineralization. Based on current research in the 2010s of the Volga, Kama and Don cascade reservoirs, 14 variants of microcystin structures were identified, the diversity of which depended on the composition of the producing species. Using PCR analysis, the main producers of microcystins (Microcystis and Dolichospermum) were identified. Cyanobacteria Cuspidothrix issatschenkoi and/or Raphidiopsis mediterranea have been identified as possible producers of neurotoxic anatoxin-a in the Tsimlyansk Reservoir. It was shown that water temperature and nitrogen were the greatest importance for development of microcystin-producing species of cyanobacteria.

FEATURES OF THE SEASONAL DYNAMICS OF PHYTOPLANKTON AT THE LEFT BANK OF THE VOLGA REACH OF KUIBYSHEV RESERVOIR (REPUBLIC OF TATARSTAN, RF)

Biocenosis of shallow waters of lowland reservoirs lives in various habitat regimes and are characterized by a special structural and functional organization. To fully elucidate these features, it is necessary to research several hydrologically different areas simultaneously. This study was conducted to evaluate the effect of seasonal dynamics on the phytoplankton community of the Volga reach of the Kuibyshev reservoir near the left bank. During the observation period, 112 taxa were found in the phytoplankton of the studied site. The greatest number of taxa were identified from the groups of diatoms (44%) and green (28%) algae. Some other less diverse groups are blue-green (16%), Chrysophyta (6%), cryptophyta and dinophyta (3%), etc. Cosmopolitan and planktonic species of algae prevail in terms of environmentally-geographical characteristics. Concerning halobility, most species are indifferent, and in terms of pH, the most common are the indifferent alkaliphile + alkalibiontic algae. The total abundance and biomass of planktonic algae range 8.49-1661.09 mln.cl./l and 10.28 -114.11 mg/l respectively. Some important dominant species are blue-green algae Microcystis aeruginosa f. flos-aquae, Aphanizomenon flos-aquae, Anabaena flos-aquae, Anabaena scheremetievi, Aulacoseira italica, Navicula sp., Carteria globosa, Chlamydomonas sp., Pandorina morum, Scenedesmus guadricauda. Seasonal dynamics of phytoplankton have two peaks of abundance and biomass which are at the end of the first decade of July and in the second decade of August. Both maxima are due to the massive development of blue-green algae, which causes water to “bloom”. The phytoplankton of the investigated section of the Kuibyshev reservoir is dominated by β-mesosaprobic organisms.

Exogenous shore processes in water reservoirs of Belarus

The article presents the results of observations and research on the dynamics of exogenous erosion processes on the shores of lowland reservoirs in Belarus. Features and regularities of the dynamics of development of exogenous shores subject to abrasion-processing and an assessment of planned and profile stability of coastal slopes on the basis of proposed criteria are presented. The relationship between exogenous processes and accumulation processes was determined, the approaches and criteria for determining the stability of reservoir shores based on the hydrological regime of reservoirs and ground conditions were developed.

Hydrochemical differentiation of selected reservoirs in Carpathian Mts. and Eastern European Lowland

The aim of the analysis was to compare physicochemical parameters and chemical composition of two groups of artificial reservoirs, mountain and lowland ones, characterised by different parameters and functions. Three mountain artificial reservoirs (Klimkówka, Dobczyce, Czorsztyn) located in the Upper Vistula basin (Carpathian Mountains in Poland) and three lowland reservoirs (Ivankovo, Verhnevolzhskoye, Vyshnevolotzkoye) located in the Upper Volga basin (Eastern European Lowland in Russia) were selected for the study. Data for the summer season in 2009-2013 were used in the analysis. Mountain reservoirs display high water concentrations of sulphates, chlorides and biogenic nitrates, and lower concentrations of ammonium and oxygen indicator in relation to lowland reservoirs. Similar concentrations of phosphates were noticed in both the mountain and the lowland reservoirs. The hydrochemical differentiation between the individual mountain reservoirs was small, and statistically significant differences only occurred for SEC. Greater differentiation of the hydrochemical parameters was found among the lowland reservoirs. Statistically significant differences were demonstrated with regard to SEC, Cl- and NO3-.

Modeling soil salinization at the downstream of a lowland reservoir

Soil salinization is a crucial issue in arid and semi-arid regions, especially for reservoir-based irrigation systems. In this study, the HYDRUS-1D model was used to investigate soil salinity resulting from seepage from a lowland reservoir in Xinjiang province, China. After successfully developing a model to simulate field observations, it was used to evaluate four hypothetical scenarios with different groundwater (GW) salinities and depths to GW. The model was calibrated, validated, and run for scenarios with periods of 367, 363, and 436 days. Root mean square error values of soil water and soil salinity ranged from 0.000 to 0.053 cm3/cm3 and 0.56 to 5.66 g/L, respectively, during calibration, and from 0.009 to 0.039 cm3/cm3 and 1.86 to 7.52 g/L, respectively, during validation. The results indicate that soil salinity downstream of the reservoir depends strongly on the depth to the GW level, while GW salinity has a much smaller impact. Controlling leakage from lowland reservoirs to avoid rising GW levels is therefore important to minimize soil salinization. These findings are generally useful for lowland reservoir design and construction, and for irrigation management in arid regions.

Littoral 0+ fish assemblages in three reservoirs of the Nové Mlýny dam (Czech Republic)

A synchronous study of 0+ juvenile fish in three lowland reservoirs (Mušov, Věstonice, Nové Mlýny) of the Nové Mlýny dam (Czech Republic) was conducted in July 1997. Fish were sampled by fry beach seine and backpack electro fishing gear at 32 sites in three types of inshore habitats: concrete stepped embankment, stony rip-rap and sandy-gravel beach. In total, we registered 0+ juvenile fish of 17 species and one hybrid. The most common species was bleak Alburnus alburnus (62.7%), followed by roach Rutilus rutilus (12.8%), ide Leuciscus idus (6.2%) and asp Aspius aspius (5.5%). More than 53% of 0+ fish samples were caught in beach sites, 43% in rip-rap sites and only 3.4% in concrete embankment. The littoral assemblages of 0+ fish differed between the three adjacent reservoirs and also between the shoreline types.