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  • 2020-2024  (2)
  • 2010-2014  (28)
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  • 1
    Publication Date: 2024-03-28
    Description: The Arctic Ocean (AO) is being rapidly transformed by global warming, but its biodiversity remains understudied for many planktonic organisms, in particular for unicellular eukaryotes that play pivotal roles in marine food webs and biogeochemical cycles. The aim of this study was to characterize the biogeographic ranges of species that comprise the contemporary pool of unicellular eukaryotes in the AO as a first step toward understanding mechanisms that structure these communities and identifying potential target species for monitoring. Leveraging the Tara Oceans DNA metabarcoding data, we mapped the global distributions of operational taxonomic units (OTUs) found on Arctic shelves into five biogeographic categories, identified biogeographic indicators, and inferred the degree to which AO communities of unicellular eukaryotes share members with assemblages from lower latitudes. Arctic/Polar indicator OTUs, as well as some globally ubiquitous OTUs, dominated the detection and abundance of DNA reads in the Arctic samples. OTUs detected only in Arctic samples (Arctic-exclusives) showed restricted distribution with relatively low abundances, accounting for 10–16% of the total Arctic OTU pool. OTUs with high abundances in tropical and/or temperate latitudes (non-Polar indicators) were also found in the AO but mainly at its periphery. We observed a large change in community taxonomic composition across the Atlantic-Arctic continuum, supporting the idea that advection and environmental filtering are important processes that shape plankton assemblages in the AO. Altogether, this study highlights the connectivity between the AO and other oceans, and provides a framework for monitoring and assessing future changes in this vulnerable ecosystem.
    Keywords: Marine protists ; Unicellular ; Phytoplankton ; Global change ; Advection ; Environmental filtering
    Repository Name: National Museum of Natural History, Netherlands
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 2
    Publication Date: 2012-08-29
    Description: Meromictic lakes are useful biogeochemical models because of their stratified chemical gradients and separation of redox reactions down the water column. Perennially ice-covered meromictic lakes are particularly stable, with long term constancy in their density profiles. Here we sampled Lake A, a deep meromictic lake at latitude 83°N in High Arctic Canada. Sampling was before (May) and after (August) an unusual ice-out event during the warm 2008 summer. We determined the bacterial and archaeal community composition by high-throughput 16S rRNA gene tag-pyrosequencing. Both prokaryote communities were stratified by depth and the Bacteria differed between dates, indicating locally driven selection processes. We matched taxa to known taxon-specific biogeochemical functions and found a close correspondence between the depth of functional specialists and chemical gradients. These results indicate a rich microbial diversity despite the extreme location, with pronounced vertical structure in taxonomic and potential functional composition, and with community shifts during ice-out. Scientific Reports 2 doi: 10.1038/srep00604
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
    Published by Springer Nature
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  • 3
    Publication Date: 2014-04-12
    Description: Thaumarchaeota and the gene encoding for a subunit of ammonia monooxygenase (amoA) are ubiquitous in Polar Seas, and some Thaumarchaeota also have a gene coding for ureC, diagnostic for urease. Using quantitative PCR we investigated the occurrence of genes and transcripts of ureC and amoA in Arctic samples from winter, spring and summer. AmoA genes, ureC genes and amoA transcripts were always present, but ureC transcripts were rarely detected. Over a 48 h light manipulation experiment amoA transcripts persisted under light and dark conditions, but not ureC transcripts. In addition, maxima for amoA transcript were nearer the surface compared to amoA genes. Clone libraries using DNA template recovered shallow and deep amoA clades but only the shallow clade was recovered from cDNA (from RNA). These results imply environmental control of amoA expression with direct or indirect light effects, and rare ureC expression despite its widespread occurrence in the Arctic Ocean. Scientific Reports 4 doi: 10.1038/srep04661
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
    Published by Springer Nature
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  • 4
    Publication Date: 2012-09-07
    Description: Global gaseous nitrogen (N2) fixation rates may be underestimated and data is lacking from many regions without conspicuous diazotrophic cyanobacteria, such as cold oceans. We estimated N2 fixation rates at diverse sites in the Canadian Arctic, including the mouth of the Mackenzie River, the offshore Beaufort Sea, Lancaster Sound, Baffin Bay and a river influenced fjord. We also identified potential diazotrophic communities using a targeted survey of the nifH gene. Nitrogen fixation rates ranged from 0.02 nmol N L−1 d−1 in Baffin Bay to 4.45 nmol N L−1 d−1 in the Mackenzie River plume. Sequences recovered from the nifH gene survey belonged mainly to Cluster III, a group of nifH sequences associated with diverse microorganisms, with some α- and γ-proteobacteria nifH genes at most sites. Cyanobacteria nifH genes with best matches to Nostocales, which are common in Arctic freshwaters, were recovered from the marine Beaufort Sea. The geographic pattern of N2 fixation rates and nifH gene identities suggest that the Mackenzie River is the source of a diazotrophic community that contributes new nitrogen to the nitrogen-depleted surface waters of the Beaufort Sea. This first record of N2 fixation at high latitudes refines our understanding of the global nitrogen budget.
    Print ISSN: 0886-6236
    Electronic ISSN: 1944-9224
    Topics: Biology , Chemistry and Pharmacology , Geography , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 5
    Publication Date: 2022-01-31
    Description: Marine and freshwater polar environments are characterized by intense physical forces and strong seasonal variations. The persistent cold and sometimes inhospitable conditions create unique ecosystems and habitats for microbial life. Polar microbial communities are diverse productive assemblages, which drive biogeochemical cycles and support higher food-webs across the Arctic and over much of the Antarctic. Recent studies on the biogeography of microbial species have revealed phylogenetically diverse polar ecotypes, suggesting adaptation to seasonal darkness, sea-ice coverage and high summer irradiance. Because of the diversity of habitats related to atmospheric and oceanic circulation, and the formation and melting of ice, high latitude oceans and lakes are ideal environments to investigate composition and functionality of microbial communities. In addition, polar regions are responding more dramatically to climate change compared to temperate environments and there is an urgent need to identify sensitive indicators of ecosystem history, that may be sentinels for change or adaptation. For instance, Antarctic lakes provide useful model systems to study microbial evolution and climate history. Hence, it becomes essential and timely to better understand factors controlling the microbes, and how, in turn, they may affect the functioning of these fragile ecosystems. Polar microbiology is an expanding field of research with exciting possibilities to provide new insights into microbial ecology and evolution. With this Research Topic we seek to bring together polar microbiologists studying different aquatic systems and components of the microbial food web, to stimulate discussion and reflect on these sensitive environments in a changing world perspective.
    Keywords: GC1-1581 ; QR1-502 ; Q1-390 ; polar ; microeukaryotes ; bacteria ; microbiology ; phytoplankton ; Antarctica ; Arctic ; aquatic ; archaea ; climate change
    Language: English
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  • 6
    Publication Date: 2023-01-13
    Keywords: Arctic Ocean; Bottle, Niskin; CANADA-BASIN_001; CANADA-BASIN_002; CANADA-BASIN_003; CANADA-BASIN_004; CANADA-BASIN_005; CANADA-BASIN_006; CANADA-BASIN_007; CANADA-BASIN_008; CANADA-BASIN_009; CANADA-BASIN_010; CANADA-BASIN_011; CANADA-BASIN_012; CANADA-BASIN_013; CANADA-BASIN_014; CANADA-BASIN_015; CANADA-BASIN_017; CANADA-BASIN_018; CANADA-BASIN_019; CANADA-BASIN_020; CANADA-BASIN_021; CANADA-BASIN_022; CANADA-BASIN_023; CANADA-BASIN_024; CANADA-BASIN_025; CANADA-BASIN_026; CANADA-BASIN_027; CANADA-BASIN_028; CANADA-BASIN_029; CANADA-BASIN_030; CANADA-BASIN_031; CANADA-BASIN_032; CANADA-BASIN_033; CANADA-BASIN_034; CANADA-BASIN_035; CANADA-BASIN_036; CANADA-BASIN_037; CANADA-BASIN_038; CANADA-BASIN_039; CANADA-BASIN_040; CANADA-BASIN_041; CANADA-BASIN_042; CANADA-BASIN_043; CANADA-BASIN_044; CANADA-BASIN_045; CANADA-BASIN_046; CANADA-BASIN_047; CANADA-BASIN_048; CANADA-BASIN_049; CANADA-BASIN_050; CANADA-BASIN_051; CANADA-BASIN_052; CANADA-BASIN_053; CANADA-BASIN_054; CANADA-BASIN_055; CANADA-BASIN_056; CANADA-BASIN_057; CANADA-BASIN_058; CANADA-BASIN_059; CANADA-BASIN_060; CANADA-BASIN_061; CANADA-BASIN_062; CANADA-BASIN_063; CANADA-BASIN_064; CANADA-BASIN_065; CANADA-BASIN_066; CANADA-BASIN_067; CANADA-BASIN_068; CANADA-BASIN_069; CANADA-BASIN_070; CANADA-BASIN_071; CANADA-BASIN_072; CANADA-BASIN_073; CANADA-BASIN_074; CANADA-BASIN_075; CANADA-BASIN_076; CANADA-BASIN_077; CANADA-BASIN_078; CANADA-BASIN_079; CANADA-BASIN_080; CANADA-BASIN_081; CANADA-BASIN_082; CANADA-BASIN_083; CANADA-BASIN_084; CANADA-BASIN_085; CANADA-BASIN_086; CANADA-BASIN_087; CANADA-BASIN_088; CANADA-BASIN_089; CANADA-BASIN_090; CANADA-BASIN_091; CANADA-BASIN_092; CANADA-BASIN_093; CANADA-BASIN_094; CANADA-BASIN_095; CANADA-BASIN_096; CANADA-BASIN_097; CANADA-BASIN_098; CANADA-BASIN_099; CANADA-BASIN_100; CANADA-BASIN_101; CANADA-BASIN_102; CANADA-BASIN_103; CANADA-BASIN_104; CANADA-BASIN_105; CANADA-BASIN_106; CANADA-BASIN_107; CANADA-BASIN_108; CANADA-BASIN_109; CANADA-BASIN_110; CANADA-BASIN_111; CANADA-BASIN_112; CANADA-BASIN_113; CANADA-BASIN_114; CANADA-BASIN_115; CANADA-BASIN_116; CANADA-BASIN_117; CANADA-BASIN_118; CANADA-BASIN_119; CANADA-BASIN_120; CANADA-BASIN_121; CANADA-BASIN_122; CANADA-BASIN_123; CANADA-BASIN_124; CANADA-BASIN_125; CANADA-BASIN_126; CANADA-BASIN_127; CANADA-BASIN_128; CANADA-BASIN_129; CANADA-BASIN_130; CANADA-BASIN_131; CANADA-BASIN_132; CANADA-BASIN_133; CANADA-BASIN_134; CANADA-BASIN_135; CANADA-BASIN_136; CANADA-BASIN_137; CANADA-BASIN_138; CANADA-BASIN_139; CANADA-BASIN_140; CANADA-BASIN_141; CANADA-BASIN_142; CANADA-BASIN_143; CANADA-BASIN_144; CANADA-BASIN_145; CANADA-BASIN_146; CANADA-BASIN_147; CANADA-BASIN_148; CANADA-BASIN_149; CANADA-BASIN_150; CANADA-BASIN_151; CANADA-BASIN_152; CANADA-BASIN_153; CANADA-BASIN_154; CANADA-BASIN_155; CANADA-BASIN_156; CANADA-BASIN_157; CANADA-BASIN_158; CANADA-BASIN_159; CANADA-BASIN_16; CANADA-BASIN_160; CANADA-BASIN_161; CANADA-BASIN_162; CANADA-BASIN_163; CANADA-BASIN_164; Date/Time of event; DEPTH, water; Event label; Flow cytometry; Latitude of event; Longitude of event; NIS; Prokaryotes
    Type: Dataset
    Format: text/tab-separated-values, 1467 data points
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  • 7
    Publication Date: 2022-05-26
    Description: © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS Biology 12 (2014): e1001889, doi:10.1371/journal.pbio.1001889.
    Description: Microbial ecology is plagued by problems of an abstract nature. Cell sizes are so small and population sizes so large that both are virtually incomprehensible. Niches are so far from our everyday experience as to make their very definition elusive. Organisms that may be abundant and critical to our survival are little understood, seldom described and/or cultured, and sometimes yet to be even seen. One way to confront these problems is to use data of an even more abstract nature: molecular sequence data. Massive environmental nucleic acid sequencing, such as metagenomics or metatranscriptomics, promises functional analysis of microbial communities as a whole, without prior knowledge of which organisms are in the environment or exactly how they are interacting. But sequence-based ecological studies nearly always use a comparative approach, and that requires relevant reference sequences, which are an extremely limited resource when it comes to microbial eukaryotes. In practice, this means sequence databases need to be populated with enormous quantities of data for which we have some certainties about the source. Most important is the taxonomic identity of the organism from which a sequence is derived and as much functional identification of the encoded proteins as possible. In an ideal world, such information would be available as a large set of complete, well-curated, and annotated genomes for all the major organisms from the environment in question. Reality substantially diverges from this ideal, but at least for bacterial molecular ecology, there is a database consisting of thousands of complete genomes from a wide range of taxa, supplemented by a phylogeny-driven approach to diversifying genomics. For eukaryotes, the number of available genomes is far, far fewer, and we have relied much more heavily on random growth of sequence databases, raising the question as to whether this is fit for purpose.
    Description: This project was funded by the Gordon and Betty Moore Foundation (GBMF; Grants GBMF2637 and GBMF3111) to the National Center for Genome Resources (NCGR) and the National Center for Marine Algae and Microbiota (NCMA).
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/msword
    Format: application/pdf
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  • 8
    Publication Date: 2010-10-16
    Print ISSN: 1867-1616
    Electronic ISSN: 1867-1624
    Topics: Biology
    Published by Springer
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  • 9
    Publication Date: 2013-12-21
    Print ISSN: 0722-4060
    Electronic ISSN: 1432-2056
    Topics: Biology
    Published by Springer
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  • 10
    Publication Date: 2011-06-14
    Print ISSN: 0722-4060
    Electronic ISSN: 1432-2056
    Topics: Biology
    Published by Springer
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