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Stroynov Ya.V., Philippov D.A. 2017. Bacterio- and virioplankton in water bodies of a raised bog (Vologda oblast, Russia). Inland Water Biology, 10(1): 37–43. DOI: 10.1134/S1995082917010175 The abundance of virio-and bacterioplankton and the role of viruses in the mortality of heterotrophic bacteria have been studied in three different mire water bodies (lagg, hollow, and stream) in the Shichengskoe raised bog. The abundance of bacteria (up to 93 million cells/mL) and viruses (up to 152 million particles/mL) reached very high values. Considerable differences were found between the mire water bodies in seasonal dynamics and average values of the studied parameters. The ratio of the number of virioplankton to the number of bacterioplankton (median values from 1.3 in a hollow to 5.6 in a stream) is in low ranges of values which are available in literature sources. Viruses did not have a considerable direct effect on bacterioplankton while lysing ≤7.8% of the bacterial production.

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Background: The paper is based on the dataset whose purpose was to deliver, in the form of GBIF-mediated data, diverse materials on the biodiversity of a large mire, Shichengskoe mire (Vologda Region, north-western Russia), including its various mire sites and intra-mire water bodies. The dataset was based on our materials collected for two decades (from 2000 to 2021) in different parts and biotopes of the Shichengskoe mire and complemented by scarce data obtained previously by other researchers. The data contain materials on the diversity of Animalia (2886 occurrences), Bacteria (22), Chromista (256), Fungi (111), Plantae (2463) and Protozoa (131). Within the study period, the most detailed and long-term biodiversity studies were carried out for higher plants and invertebrates. On the other hand, the data on the composition of lichens, protozoa, algae, basidiomycetes, some groups of invertebrates and, to a lesser extent, lichens and vertebrates are far less comprehensive and require further substantial research efforts. The list includes occurrences from both the peatland (mire sites and mire margins different in typology) and the objects of the mire hydrographic network. In a standardised form, this article summarises both already published (mainly in Russian) and unpublished materials. New information: The paper summarises the results of long-term research on the biodiversity of a boreal mire, including its hydrographic network. A total of 5869 occurrences were included in the dataset published in the Global Biodiversity Information Facility (GBIF, gbif.org) for the first time. According to the GBIF taxonomic backbone, the dataset covers 1358 taxa, including 1250 lower-rank taxa (species, subspecies, varieties, forms) and 108 taxa identified to the genus level. Several species found in the Shichengskoe mire, mainly belonging to Bacteria, Chromista and Protozoa, have never been listed in GBIF for the territory of Russia before. The overwhelming majority of occurrences and identified species came from the territory of Shichengskiy Landscape Reserve. Due to our work, this Reserve is now the most studied regional reserve in the Vologda Region with respect to biodiversity. By the number of revealed species, it is close to two federal protected areas: Darwinskiy State Nature Biospheric Reserve and National Park "Russkiy Sever".
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This unique textbook takes a broad look at the rapidly expanding field of freshwater microbiology. Concentrating on the interactions between viruses, bacteria, algae, fungi and micro-invertebrates, the book gives a wide biological appeal. Alongside conventional aspects such as phytoplankton characterisation, seasonal changes and nutrient cycles, the title focuses on the dynamic and applied aspects that are not covered within the current textbooks in the field. Complete coverage of all fresh water biota from viruses to invertebrates. Unique focus on microbial interactions including coverage of biofilms, important communities on all exposed rivers and lakes. New information on molecular and microscopical techniques including a study of gene exchange between bacteria in the freshwater environment. Unique emphasis on the applied aspects of freshwater microbiology with particular emphasis on biodegradation and the causes and remediation of eutrophication and algal blooms.
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The timing of lytic phage development and the relationship between host generation times and latent periods were investigated by electron microscopy of one-step growth experiments in two strains of marine Vibrio species. Results were used in a correction factor developed to interpret field studies of phage-infected marine bacteria. Both the number of mature phage per average cell section and the percentage of cells with mature phage increased exponentially by 73-86% into the latent periods. Assuming that bacterial infection and lysis take place continually in the ocean, conversion factors for relating the percentage of visibly infected bacteria to the total percentage of the bacterial community that are phage-infected were calculated as 3.70-7.14. When this range of factors was applied to previously-collected field data [Proctor LM, Fuhrman JA (1990) Nature (Lond) 343:60-62; Proctor LM, Fuhrman JA (1991) Mar Ecol Prog Ser 69:133-142] from 3 to 31% of the free-living bacteria and 3 to 26% of particulate-associated bacteria appeared to be phage-infected at any given time. Based upon a steady-state model in which half the daughter cells survive to divide again, the percent of total mortality would be twice the total percentage of phage-infected cells. From 6 to 62% and from 6 to 52% of mortality for the free-living and particulate-associated bacterial community, respectively, may be due to viruses.
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Composition and seasonal dynamics of phytoplankton, bacteria, and zooplankton (including heterotrophic flagellates, ciliates, rotifers and crustaceans) were studied in 55 lakes in Northern Germany with different trophic status, ranging from mesotrophic to hypertrophic. Mean abundance and biomass of all groups increased significantly with trophic level of the lake, but bacteria and metazooplankton showed only a weak correlation and a slight increase with chlorophyll concentration. Composition of phytoplankton showed a dominance of cyanobacteria in hypertrophic lakes, whereas the importance of chrysophytes and dinophytes decreased with an increase in trophic status. Protozoans (heterotrophic flagellates and ciliates) made up 24% (mesotrophic lakes) to 42% (hypertrophic lakes) of total zooplankton biomass on average, and were dominated by ciliates (62‐80% of protozoan biomass). Seasonally, protozoans can build up to 60% of zooplankton biomass in spring, when heterotrophic flagellates can contribute � 50% to protozoan biomass. Correlation analyses revealed significant relationships between the planktonic groups and indicated that pelagic food webs are influenced by both bottom-up as well as top-down mechanisms. Comparing lakes along a trophic gradient, resource parameters seem to be of major importance, whereas seasonal changes within a lake were perhaps regulated by the presence of predators.
Chapter
Viruses are typically viewed as microorganisms responsible for diseases in other, larger organisms. During the last one-and-a-half decades, it has become increasingly clear that they are (together with bacteria) the most abundant microorganisms and life forms, and that only a relatively small number are pathogenic to humans; the vast majority play a critical role in aquatic ecosystems. Ample research, plenty of it being conducted in marine systems, has revealed that viruses are involved in the cycling of nutrients and carbon; however, the impact on their hosts’ distribution and on the genetic information harbored in aquatic organisms is still at the dawn of comprehensive scientific understanding. Therefore, this field has a tremendous potential for further development and is already widely accepted as an integral and promising discipline in the inland water sciences as well. This chapter will not cover the survival and distribution of human, animal, and plant pathogenic viruses, since topics related to such disease-causing viruses have been reviewed extensively elsewhere. Rather, this chapter will provide a basic insight into aquatic virus ecology, presenting a short overview on current knowledge. It also provides suggestions about important and excellent sources for further reading.
Article
The relative contribution of viral lysis to overall mortality in aquatic bacterial populations is often estimated as twice the frequency of infected cells (FIC). The 'factor-of-two rule' upon which this estimate is based assumes (l) steady-state conditions, (2) that latent period is equivalent to generation time, a n d (3) that infected cells are not grazed. FIC values for this calculation are themselves derived from measurements of the frequency of vlsibly infected cells (FVIC) by the use of a slmple conversion factor. A steady-state model was developed to more ngorously define the relationships between FIC, FVIC, and the fraction of mortality from viral lysis (FMVL). This model shows that even under the restrictive assumptions listed above, the factor-of-two rule systematically overestimates FMVL for typ-ically reported values of FVIC. The model also shows that although grazing on infected cells further reduces FMVL for a given estimate of FIC, at the same time such grazing increases FIC for a given mea-surement of FVIC. In combination, these 2 effects mnimize the influence of grazing on the calculation of FMVL from FVIC. Overall, the relationship between FMVL and FVIC is well approxin~ated as fol-lows: FMVL S FVIC/[y ln(2) (1 -E -FVIC)], where y = the ratio between the latent period and genera-tion time, and E = the fraction of the latent period during which viral particles are not yet visible. Using typically observed values of FVIC, and assuming that y = 1 (per assumption 2, above) and E = 0 186 (per literature estimates), the model suggests that, on average, viral lysis accounts for approximately 22% (range: 4.5 to 45' ::) of total bacterial mortality in a range of aquatic environments, corresponding to a mean overestimate of 24 % (range: 4 to 44'%) by the factor-of-two rule. Perhaps most importantly, the model shows that calculations of FMVL from FIC or FVIC are very sensitive to changes in the relative length of the latent period (y) and in the assumed proportion of the latent period during which viral par-ticles are not recognizable (E). Constraining these 2 factors would greatly improve the reliability of FMVL calculations.
Article
1. Viruses are the most abundant biological entities on the planet, and sediments provide a highly suitable environment for them. This review presents the first comparative synthesis of information on the fresh water and marine viriobenthos and explores differences and similarities to the better known virioplankton. We present methods for studying life cycles of the viriobenthos, data on viral distribution and diversity, interactions with host microbes, and information on the role of viruses in benthic food webs and biogeochemical cycles.
Article
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