DISTRIBUTION OF ALIEN SPECIES OF MACROZOOBENTHOS AND THE SPECIES COENOTIC COMPLEXES IN THE KAMA RESERVOIRS

The results of studies on the distribution of alien species in macrozoobenthic communities in the reservoirs of the Kama River cascade are provided. Twenty five alien species of the Ponto-Caspian and Ponto-Azov origins and 1 species - a representative of the Lake Baikal fauna - were registered. Differences in the species composition and structural characteristics of invaders of macrozoobenthos in the Kama and Volga reservoirs were shown. It was noted that mollusks of the genus Dreissena dominate in biomass in most of the studied biotopes. Three types of coenotic complexes of alien species have been identified: psammorelophilic profundal, characteristic for the Nizhnekamsk Reservoir and the Volgo-Kamsky and Kamsky reaches of the Kuibyshev Reservoir; the psammorelophilic coastal in Nizhnekamsk Reservoir; and the psammorelophilic coastal in Votkinsk and Kama reservoirs.

Distribution and species composition of zooplankton (rotifers and crustaceans) in the Basin of the Middle Volga River, Russia

The presented dataset contains information on the distribution and species composition of zooplankton (rotifers and crustaceans) registered in the Basin of the Middle Volga River, Russia. The studies have been performed in the Kuibyshev Reservoir (Samara Oblast and the Republic of Tatarstan), the Saratov Reservoir (Samara Oblast), in several lakes (Raifskoe, Gniloe, Krugloe and Lenevo) in the Volzhsko-Kamsky State Biosphere Reserve (Republic of Tatarstan) and in Lake Aslikul, one of the largest lakes of the Middle Volga River Basin, located in the Asly-Kul Natural Park (Republic of Bashkortostan). The hydrobiological data were obtained and published from 1957 to 2020. In total, the dataset includes 5141 records of 111 zooplankton species (including 17 subspecies), belonging to 45 genera. These are mainly native species - 98.5%, while the naturalised, including invasive species, accounts for less than 1.5%. A total of 5141 records have been published on the taxonomic diversity and occurrence of zooplankton (rotifers and crustaceans) in the Middle Volga River Basin. Each record includes information about the place and date of finding the specimen, its taxonomy, occurrence and abundance and the collector. If the information about the find has been published, a link to the corresponding reference is provided. The presented dataset supplements the data on the distribution of zooplankton species in the European part of Russia. Data on zooplankton in the Middle Volga River Basin are published for the first time.

Assessment of Shoreline Transformation Rates and Landslide Monitoring on the Bank of Kuibyshev Reservoir (Russia) Using Multi-Source Data

This study focuses on the Kuibyshev reservoir (Volga River basin, Russia)—the largest in Eurasia and the third in the world by area (6150 km2). The objective of this paper is to quantitatively assess the dynamics of reservoir bank landslides and shoreline abrasion at active zones based on the integrated use of modern instrumental methods (i.e., terrestrial laser scanning—TLS, unmanned aerial vehicle—UAV, and a global navigation satellite system—GNSS) and GIS analysis of historical imagery. A methodology for the application of different methods of instrumental assessment of abrasion and landslide processes is developed. Different approaches are used to assess the intensity of landslide and abrasion processes: the specific volume and material loss index, the planar displacement of the bank scarp, and the planar-altitude analysis of displaced soil material based on the analysis of slope profiles. Historical shoreline position (1958, 1985, and 1987) was obtained from archival aerial photo data, whereas data for 1975, 1993, 2010, 2011, and 2012 were obtained from high-resolution satellite image interpretation. Field surveys of the geomorphic processes from 2002, 2003, 2005, 2006, 2014 were carried out using Trimble M3 and Trimble VX total stations; in 2012–2014 and 2019 TLS and UAV surveys were made, respectively. The monitoring of landslide processes showed that the rate of volumetric changes at Site 1 remained rather stable during the measurement period with net material losses of 0.03–0.04 m−3 m−2 yr−1. The most significant contribution to the average annual value of the material loss was snowmelt runoff. The landslide scarp retreat rate at Site 2 showed a steady decreasing trend, due to partial overgrowth of the landslide accumulation zone resulting in its relative stabilization. The average long-term landslide scarp retreat rate is—2.3 m yr−1. In 2019 earthworks for landscaping at this site have reduced the landslide intensity by more than 2.5 times to—0.84 m yr−1.

FIRST DATA ON PARASITES OF NEOGOBIUS ILJINI (PERCIFORMES, GOBIIDAE) OF THE MIDDLE VOLGA

The results of a study of the fauna of multicellular parasites of the Caspian bighead goby Neogobius iljini (Vasiljeva et Vasiljev, 1996) in three reaches of the Kuibyshev reservoir (Middle Volga) are presented. Twelve species and undefined forms of parasites were found, including a specific to the fam. Gobiidae metacercaria Holostephanus cobitidis . The most diverse fauna of macroparasites is observed in the lower reaches of the reservoir (Priplotinny reach). The dominant species in the parasite fauna of the Caspian goby of the studied reservoir is the alien fluke Nicolla skrjabini , whose natural range is limited to the rivers of the Azov and Black seas basin.

Spatiotemporal distribution of planktonic ciliates in the Kuybyshev water reservoir in the area of Klimovskaya narrowing

The paper attempts to link changes in quantitative characteristics of the community of free-living planktonic ciliates and the nature of their vertical distribution with the operation mode of the hydroelectric power station in the reservoir. Low values of the abundance (8–1,560 thousand cells / m3) and biomass (0.1–66.9 mg / m3) of ciliates in the water column, and a fairly wide range of their variation in the reservoir are probably due to the oscillatory nature of the hydrological regime in the regulated river conditions. The vertical distribution of free-living planktonic ciliates of the near-dam section of the Kuibyshev reservoir was studied at all times of the day on all days of the week. The species were distributed throughout the water column to the bottom with some preference for the surface (0–2 m) and medium (4–10 m) layers. There was no clear attachment of individual species to certain layers in the conditions of homothermy. The preference for certain horizons is due to some biological characteristics of the species (for example, peritriches on the coenobia of algae in the surface layers), departure from “blooming spots”, etc. No data in favor of vertical migrations or “turbulent transport” has yet been revealed. The influence of the weekly regime of regulation of the Zhigulevskaya HPS, in which at the end of the working week, the fluctuation amplitude of many hydrological parameters probably decreases, is manifested in an increase in the abundance and biomass of planktonic ciliates at this time.The nature of the daily change in the average ciliates abundance in the water column was the same for a variant of the community in working days and was in antiphase with the change in the community abundance on weekends, namely: the maximum number on working days and on weekends was recorded in the evening (20.00) and in the daytime (14.00), respectively.

Assessment of modern shoreline transformation rates on the banks of one of the largest reservoirs in the world (Kuibyshev reservoir, Russia) using instrumental methods

The study object is the Kuibyshev reservoir. The objective is to quantitatively assess reservoir bank landslides and shoreline abrasion in active zones based on the integrated use of modern instrumental methods. Different approaches are used to assess the intensity of landslide and abrasion processes: the specific volume and material loss index, the planar displacement of the bank scarp, and the planar-altitude analysis displacements of soil masses based on the analysis of slope profiles. Shoreline position for the past periods (1958, 1985, and 1987) was obtained from archival aerial photography data; data for 1975, 1993, 2010, 2011, and 2012 were obtained from high-resolution satellite image interpretation. Field surveys of these geomorphic processes at the study areas in 2002, 2003, 2005, 2006, 2014 were carried out using total stations; in 2012-2014 using terrestrial laser scanning and a UAV survey in 2019. The monitoring of landslide processes showed that the rate of volumetric changes at Site 1 remained rather stable during the measurement period with net material losses of 0.03-0.04 m3/m2/year. The most significant contribution to the average annual value of material loss was by snowmelt runoff. The landslide scarp retreat rate at Site 2 showed a steady decreasing trend, due to partial overgrowth of the landslide accumulation zone resulting in its relative stabilization. The average long-term landslide scarp retreat rate is 2.3 m/year. In recent years, landslide control measures realized at this site have reduced the landsliding intensity by more than 2.5 times to 0.84 m/year