scholarly journals High contribution of Synechococcus to phytoplankton biomass in the aphotic hypolimnion in a deep freshwater lake (Lake Biwa, Japan)

2015 ◽  
Vol 75 (1) ◽  
pp. 69-79 ◽  
Author(s):  
H Takasu ◽  
M Ushio ◽  
JE LeClair ◽  
S Nakano
Keyword(s):  
Phytoplankton Biomass ◽  
Lake Biwa ◽  
Freshwater Lake ◽  
High Contribution

Contribution of large bacteria to bacterial biomass in a deep freshwater lake (Lake Biwa, Japan)

2020 ◽  
Vol 85 ◽  
pp. 131-139
Author(s):  
S Shen ◽  
Y Shimizu
Keyword(s):  
Cell Volume ◽  
Bacterial Cell ◽  
Lake Biwa ◽  
Bacterial Biomass ◽  
Spatial Variations ◽  
Freshwater Lake ◽  
Heterotrophic Nanoflagellates ◽  
Bacterial Productivity ◽  
Transmission Electron ◽  
Seasonal And Spatial Variations

Despite the importance of bacterial cell volume in microbial ecology in aquatic environments, literature regarding the effects of seasonal and spatial variations on bacterial cell volume remains scarce. We used transmission electron microscopy to examine seasonal and spatial variations in bacterial cell size for 18 mo in 2 layers (epilimnion 0.5 m and hypolimnion 60 m) of Lake Biwa, Japan, a large and deep freshwater lake. During the stratified period, we found that the bacterial cell volume in the hypolimnion ranged from 0.017 to 0.12 µm3 (median), whereas that in the epilimnion was less variable (0.016 to 0.033 µm3, median) and much lower than that in the hypolimnion. Additionally, in the hypolimnion, cell volume during the stratified period was greater than that during the mixing period (up to 5.7-fold). These differences in cell volume resulted in comparable bacterial biomass in the hypolimnion and epilimnion, despite the fact that there was lower bacterial abundance in the hypolimnion than in the epilimnion. We also found that the biomass of larger bacteria, which are not likely to be grazed by heterotrophic nanoflagellates, increased in the hypolimnion during the stratified period. Our data suggest that estimation of carbon flux (e.g. bacterial productivity) needs to be interpreted cautiously when cell volume is used as a constant parametric value. In deep freshwater lakes, a difference in cell volume with seasonal and spatial variation may largely affect estimations.

Regular high contribution of Gonyostomum semen to phytoplankton biomass in a small humic lake

2002 ◽  
Vol 28 (1) ◽  
pp. 488-491
Author(s):  
Kalevi Salonen ◽  
Anna-Liisa Holopainen ◽  
Jorma Keskitalo
Keyword(s):  
Phytoplankton Biomass ◽  
Humic Lake ◽  
High Contribution ◽  
Gonyostomum Semen

scholarly journals Draft Genome Sequences of Tersicoccus phoenicis DSM 30849T, Isolated from a Cleanroom for Spacecraft Assembly, and Tersicoccus sp. Strain Bi-70, Isolated from a Freshwater Lake

2017 ◽  
Vol 5 (13) ◽  
Author(s):  
Yu Nakajima ◽  
Susumu Yoshizawa ◽  
Keiji Nakamura ◽  
Yoshitoshi Ogura ◽  
Tetsuya Hayashi ◽  
...  
Keyword(s):  
Lake Biwa ◽  
Draft Genome ◽  
Freshwater Lake ◽  
Genome Sequences ◽  
Content Type ◽  
Spacecraft Assembly

ABSTRACT Here, we report the draft genome sequences of Tersicoccus phoenicis DSM 30849T, isolated from a spacecraft assembly cleanroom at the National Aeronautics and Space Administration (NASA), and Tersicoccus sp. strain Bi-70, isolated from Lake Biwa, the largest lake in Japan. These genome sequences facilitate our understanding of the adaptation of these closely related strains to different habitats.

Effect of flow velocity on phytoplankton biomass and composition in a freshwater lake

2013 ◽  
Vol 447 ◽  
pp. 64-71 ◽  
Author(s):  
Feipeng Li ◽  
Haiping Zhang ◽  
Yiping Zhu ◽  
Yihua Xiao ◽  
Ling Chen
Keyword(s):  
Flow Velocity ◽  
Phytoplankton Biomass ◽  
Freshwater Lake

Distribution of putative denitrifying methane oxidizing bacteria in sediment of a freshwater lake, Lake Biwa

2012 ◽  
Vol 35 (4) ◽  
pp. 233-238 ◽  
Author(s):  
Hisaya Kojima ◽  
Masazumi Tsutsumi ◽  
Kanako Ishikawa ◽  
Tomoya Iwata ◽  
Marc Mußmann ◽  
...  
Keyword(s):  
Lake Biwa ◽  
Freshwater Lake ◽  
Methane Oxidizing Bacteria

scholarly journals Genome-resolved viral and cellular metagenomes revealed potential key virus-host interactions in a deep freshwater lake

2019 ◽  
Author(s):  
Yusuke Okazaki ◽  
Yosuke Nishimura ◽  
Takashi Yoshida ◽  
Hiroyuki Ogata ◽  
Shin-ichi Nakano
Keyword(s):  
Surface Waters ◽  
Lake Biwa ◽  
Freshwater Lake ◽  
Read Coverage ◽  
Freshwater Systems ◽  
Viral Genomes ◽  
Viral Propagation ◽  
Host Interactions ◽  
Vertical Partitioning ◽  
Assimilatory Sulfate Reduction

SummaryMetagenomics has dramatically expanded the known virosphere, but freshwater viral diversity and their ecological interaction with hosts remain poorly understood. Here, we conducted a metagenomic exploration of planktonic dsDNA prokaryotic viruses by sequencing both virion (<0.22 μm) and cellular (0.22–5.0 μm) fractions collected spatiotemporally from a deep freshwater lake (Lake Biwa, Japan). This simultaneously reconstructed 183 complete (i.e., circular) viral genomes and 57 bacterioplankton metagenome-assembled genomes. Analysis of metagenomic read coverage revealed vertical partitioning of the viral community analogous to the vertically stratified bacterioplankton community. The hypolimnetic community was generally stable during stratification, but occasionally shifted abruptly, presumably due to lysogenic induction. Genes involved in assimilatory sulfate reduction were encoded in 20 (10.9%) viral genomes, including those of dominant viruses, and may aid viral propagation in sulfur-limited freshwater systems. Hosts were predicted for 40 (21.9%) viral genomes, encompassing 10 phyla (or classes of Proteobacteria) including ubiquitous freshwater bacterioplankton lineages (e.g., Ca. Fonsibacter and Ca. Nitrosoarchaeum). Comparison with viral genomes derived from published metagenomes revealed viral phylogeographic connectivity in geographically isolated habitats. Notably, analogous to their hosts, actinobacterial viruses were among the most diverse, ubiquitous, and abundant viral groups in freshwater systems, with potential high lytic activity in surface waters.

scholarly journals Eutrophication and warming effects on long-term variation of zooplankton in Lake Biwa

2011 ◽  
Vol 8 (1) ◽  
pp. 593-629 ◽  
Author(s):  
C. H. Hsieh ◽  
Y. Sakai ◽  
S. Ban ◽  
K. Ishikawa ◽  
T. Ishikawa ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Phytoplankton Community ◽  
Environmental Changes ◽  
Lake Biwa ◽  
Zooplankton Community ◽  
Trophic Levels ◽  
Environmental Data ◽  
Delayed Response ◽  
Zooplankton Abundance

Abstract. We compiled and analyzed long-term (1961–2005) zooplankton community data in response to environmental variations in Lake Biwa. Environmental data indicate that Lake Biwa had experienced eutrophication (according to total phosphorus concentration) in the late 1960s and recovered to a normal trophic status around 1985, and then exhibited warming since 1990. Total zooplankton abundance showed a significant correlation with total phytoplankton biomass. Following a classic pattern, cladoceran/calanoid and cyclopoid/calanoid abundance ratio was related positively to eutrophication. Zooplankton community exhibited a significant response to the boom and bust of phytoplankton biomass as a consequence of eutrophication-reoligotriphication and warming. Moreover, our analyses suggest that the Lake Biwa ecosystem exhibited a hierarchical response across trophic levels; that is, higher trophic levels may show a more delayed response or no response to eutrophication than lower ones. We tested the hypothesis that phytoplankton community can better explain the variation of zooplankton community than bulk environmental variables, considering that phytoplankton community may directly affects zooplankton succession through predator-prey interactions. Using a variance partition approach, however, we did not find strong evidence to support this hypothesis. We further aggregate zooplankton according to their feeding types (herbivorous, carnivorous, omnivorous, and parasitic) and taxonomic groups, and analyzed the aggregated data. While the pattern remains similar, the results are less clear comparing with the results based on finely resolved data. Our research explored the efficacy of using zooplankton as bio-indicators to environmental changes at various data resolutions.

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