The chlorophyll content in water and bottom sediments of the Rybinsk Reservoir

The seasonal dynamics of chlorophyll content in the plankton and bottom sediments in the Rybinsk Reservoir were studied. The highest temporal (seasonal) variability of the chlorophyll concentration is characteristic of water, and the highest spatial variability is characteristic of bottom sediments (BSs). The positive dependence between the chlorophyll content in water and bottom sediments in the reservoir was revealed, which reflects the role of phytoplankton in the formation of bottom biotopes productivities. Average values of the ratio of water and BS chlorophyll contents were comparable to the rates of sedimentation as calculated by the data on BS probing.     

Viruses in the plankton of the Rybinsk Reservoir

The role of autochthonous viruses in the regulation of bacterioplantkon abundance and production was studied in the Rybinsk Reservoir. During the ice-free period, the number of virus-like particles varied within the range of (11.0–57.4) × 10⁶ particles/ml. The virus to bacterioplankton abundance ratio ranged within 3.0–9.4. From 4 to 25% of bacterioplankton was infected by phages. A single infected cell contained up to 80 mature virus particles. The phage-induced bacterioplankton mortality in different parts of the reservoir constituted 3.7–41.8% (22.5% on average) of bacterioplankton daily production. Heterotrophic flagellates grazed from 7.6 to 68.8% (27.5% on average) of the daily bacterial production. Thus, along with flagellates, viruses are an important factor controlling bacterioplankton development in the reservoir.     

Viruses in the plankton of the Rybinsk Reservoir

The role of autochthonous viruses in the regulation of bacterioplankton abundance and production was studied in the Rybinsk Reservoir. During the ice-free period, the number of virus-like particles varied within the range of (11.0-57.4) x 10(6) particles/ml. The virus to bacterioplankton abundance ratio ranged within 3.0-9.4. From 4 to 25% of bacterioplankton was infected by phages. A single infected cell contained up to 80 mature virus particles. The phage-induced bacterioplankton mortality in different parts of the reservoir constituted 3.7-41.8% (22.5% on average) of bacterioplankton daily production. Heterotrophic flagellates grazed from 7.6 to 68.8% (27.5% on average) of the daily bacterial production. Thus, along with flagellates, viruses are an important factor controlling bacterioplankton development in the reservoir.     

密云水库不同季节细菌群落多样性

为加强对密云水库水体状况的全面了解,对2006年11月到2007年11月不同季节水体中的微生物进行了研究.用流式细胞仪技术和LB固体培养基培养测定了水体中的细菌数目;利用PCR-DGGE技术对水体细菌的多样性和相似性进行分析.结果表明,细菌数目随季节变化有所不同,但利用流式细胞仪测定的每毫升水体细菌的数目基本上均为104数量级,而培养得到的细菌菌落数为102～103 CFU/ml,基本符合国家饮用水源的卫生标准.细菌的多样性指数也表现出随季节变化的规律,冬季(2006-11和2007-11)Shannon-Weaver多样性指数较低,为3.0左右;春季(2007-04)开始增大,至夏季(2007-07)时可高达3.3068;秋季(2007-09)又减小到3.1246.另外,密云水库细菌的优势类群有β-Proteobacteria、Actinobacteria、Cytophaga/Flexibacter/Bacteroides (CFB) 类群和Cyanobacteria. 这些资料有望为以后进一步从微生物角度评价水质提供参考.     

Toxicological and teratogenic assessment of bottom sediments from the Rybinsk Reservoir

The toxicity of bottom sediments (BSs) from different parts of the Rybinsk Reservoir has been determined by biotesting. Neither acute nor chronic toxicity are detected for ceriodaphnia Ceriodaphnia affinis Lillijeborg in tests with water extracts of sediments from all the investigated stations. The relative number of Chironomus riparius Meigen larvae with deformed mouth structures in the specimens exposed to the BSs of the reservoir is higher than in the control. Abnormalities of the mentum and mandibules (heavily chitinized structures) were the most often observed pathomorphological disturbances. The results of this study suggest that BSs from the stations located near the Cherepovets Industrial Complex (CIC) may be classified as contaminated.     

Dynamics of hydrophilic phytocenoses in the littoral of the Rybinsk Reservoir

The dynamics of overgrowths of the most common phytocenoses of higher aquatic vegetation was studied in the littoral of the Rybink Reservoir from 1986 to 2008. Long-term changes in the floristic composition of phytocenoes have been observed at geobotanical sites.     

Biology and production of mass chironomid species in the Rybinsk Reservoir

The biology, distribution and production of the following four mass species of chironomids from the shallow zone of the Rybinsk Reservoir are studied: Chironomus agilis Shobanov et Djomin, Ch. muratensis Ryser et al., Lipiniella araenicola Shilova, and Stictochironomus crassiforceps (Kieffer). Although these species differ greatly in life cycles, production, trophic states of habitats, duration, and rate of growth, their average P/B _aver coefficient values vary inconsiderably from 2.9 to 3.4; P/B _max varies from 1.4 to 1.6. Mean values of P/B _aver of 3.0 and of P/B _max of 1.5 are recommended for calculating the production of monocyclic chironomid species in fresh waters while determining the fish productivity of a waterbody or assessing losses associated with dredging.     

Functional state of the liver antioxidant system of the bream <Emphasis Type="Italic">Abramis brama</Emphasis> (L.) from Rybinsk Reservoir regions with different anthropogenic loads

The breams living in five regions of the Rybinsk Reservoir with different degrees of anthropogenic load have been assayed for the characteristics of their antioxidant system (AOS) and lipid peroxidation (LPO) system. Individuals caught at two stations in the Rybinsk Reservoir that maximally differ in the degree of pollution display different qualitative and quantitative compositions of polychlorinated biphenyls (PCBs). At the station at the Sheksninskii Reach, which is located near a local source of pollution (Cherepovets), the total content of PCBs and homologous groups of congeners is one order of magnitude higher than in the bream living at the station of the comparatively clean Molozhskii Reach. The AOS response and the generation intensity of LPO products in the bream (Abramis brama L.) liver caused by different degrees of anthropogenic pollution have been determined. The content of LPO products in the liver of the breams caught in the Sheksninskii Reach is considerably higher and the values of AOS characteristics are considerably lower than in the fish from the Molozhskii Reach. The bream living in the Molozhskii and Volzhskii Reaches are in a more favorable state than those in the Sheksninskii Reach. The AOS and LPO characteristics are an appropriate biomarker for estimating the state of the health of the fish.     

Comparative analysis of the indices of immunophysiological state in bream (<Emphasis Type=Italic>Abramis brama</Emphasis> (L.)) from parts of the Rybinsk Reservoir with different extents of pollution

The indices of the cellular and humoral components of natural immunity in bream from parts of the Rybinsk Reservoir with different extents of contamination are studied. Considerable differences were revealed in a range of parameters between the fish sampled in the Sheksninskii reach, which receives waste-waters from the Cherepovets industrial center, and the fish from the relatively unpolluted Molozhskii reach. An analysis of the data shows evidence for the active state of the mechanisms of nonspecific resistance in the fish from polluted sites.     

Activity and growth efficiency of heterotrophic bacteria in Rybinsk Reservoir

The active fraction, production, and respiration of heterotrophic bacteria are determined to assess their growth efficiency and their role in the carbon cycle in the pelagic zone of Rybinsk Reservoir in summer. The greater part of organic substances assimilated by bacteria is mineralized to CO₂. It has been established that the essential part of the constructive and energy metabolism of bacteria is supported by the input of allochthonous substances. Bacterioplankton, producing the biomass at their expense, performs functions similar to the functions of phytoplankton, and substantially supports the structural and functional organization of the planktonic food web in the reservoir.     

Nematodes in Meiobenthos and Periphyton of the Rybinsk Reservoir (Review)

This paper presents data on changes in the taxonomic composition and abundance of nematodes in meiobenthos and periphyton of the Rybinsk Reservoir in the long term. The species composition of roundworms in bottom communities is significantly richer and their number is manyfold higher than among fouling organisms. These differences are determined by the different habitat conditions at the bottom and hard substrate surfaces in the water column. In modern anthropogenically disturbed zones of various waterbodies, the biocenotic and functional roles of nematodes depend to a larger extent on food availability than on some other environmental factors limiting the development of worms. Roundworms, living under a wide range of ecological conditions, are one of the key groups of invertebrates critical for preserving aquatic life under anthropogenic stresses.     

Morphological Variability of Roach <Emphasis Type=Italic>Rutilus rutilus</Emphasis> (L.) from the Volga Reach of Rybinsk Reservoir

A comparative analysis of literature data and our own results on the morphology of roach from the Volga Reach (Rybinsk Reservoir) in different years is conducted. Recently, (from 2007 to 2010), the morphological characteristics of the roach have been similar to those observed between 1976 and 1978. The roach is characterized by an intermediate position between the herbivorous and malacophagous morphs, but it is more similar to the herbivorous morph.     

Taxonomic Diversity and Size-Morphological Structure of Bacterioplankton of the Rybinsk Reservoir

Microbiology - This is the first report on investigation of bacterioplankton taxonomic composition in the Rybinsk Reservoir by molecular biological methods. A total of 58 nucleotide sequences...     

Viruses in bottom sediments of a Mesotrophic Reservoir (Rybinsk Reservoir,Upper Volga)

The total number and morphological and size composition of viriobenthos, number of bacteria infected by viruses, and burst size, as well as virus-induced mortality, abundance, and production of bacteriobenthos, have been estimated in bottom sediments of the Rybinsk Reservoir. The total number of viriobenthos in the reservoir varies within (1.1–10.9) × 10⁹ (on average, (5.9 ± 0.6) × 10⁹) particles/cm³; the total number of virus-to-bacteria ratio ranges within 0.2–2.1 (on average 0.9 ± 0.3). A weak positive correlation is found between the abundance of benthic viruses and the abundance and production of benthic bacteria. In most surveyed parts of the reservoir, infected benthic bacteria were not found or the portion of visibly infected bacterial cells (FVIC) did not exceed 0.5% of the total abundance of bacteriobenthos (N _B). A comparatively high infection of bacteria by viruses was recorded in bottom sediments only at one deep-water station, where FVIC was 2.5 of N _B.     

Impact of common tern colonies upon the zooplankton in Rybinsk Reservoir shallow waters

The comparison of the zooplankton communities developing in the semiprotected shallow waters of Rybinsk Reservoir under the impact of common tern (Sterna hirundo Linnaeus) colonies with communities in sheltered overgrowing habitats situated apart from colonies, has reveled some peculiar features of the former: higher biomass, prevalence of cladocerans, lower share of rotifers, and decrease in species diversity.     

Distribution of Sedimentary Pigments and Macrozoobenthos in the Deepwater Part of the Rybinsk Reservoir

The spatial, seasonal, and interannual variability of content of sedimentary pigments and biomass of macrozoobenthos in the Rybinsk Reservoir (Russia) are analyzed on the basis of studies performed in 2009–2015. Specific features of the macrozoobenthos distribution depending on the characteristics of biotopes, including the content of sedimentary pigments, water depth, and water content in bottom sediments and their air-dry volumetric mass, are revealed. Correlation and principal-component analyses revealed a statistically significant positive relationship between the biomass of macrozoobenthos and the sum content of sedimentary chlorophyll a and pheopigments.     

The influence of bird colonies on the zooplankton in the Rybinsk Reservoir overgrown shallows

This article describes the peculiarities of the structural organization of zooplankton influenced by the waste products of the black-headed gull (Larus ridibundus Linnaeus) nesting colony in the protected overgrown shallow in Rybinsk Reservoir. The bird colony facilitates a modification of the zooplankton structure that is similar to the modifications of communities at early stages of eutrophication: the number of invertebrate species increases thanks to rotifers and cladocerans and the number and biomass of community increases due to cladocerans and copepods.