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      Arctic Ocean Microbial Community Structure before and after the 2007 Record Sea Ice Minimum

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          Abstract

          Increasing global temperatures are having a profound impact in the Arctic, including the dramatic loss of multiyear sea ice in 2007 that has continued to the present. The majority of life in the Arctic is microbial and the consequences of climate-mediated changes on microbial marine food webs, which are responsible for biogeochemical cycling and support higher trophic levels, are unknown. We examined microbial communities over time by using high-throughput sequencing of microbial DNA collected between 2003 and 2010 from the subsurface chlorophyll maximum (SCM) layer of the Beaufort Sea (Canadian Arctic). We found that overall this layer has freshened and concentrations of nitrate, the limiting nutrient for photosynthetic production in Arctic seas, have decreased. We compared microbial communities from before and after the record September 2007 sea ice minimum and detected significant differences in communities from all three domains of life. In particular, there were significant changes in species composition of Eukarya, with ciliates becoming more common and heterotrophic marine stramenopiles (MASTs) accounting for a smaller proportion of sequences retrieved after 2007. Within the Archaea, Marine Group I Thaumarchaeota, which earlier represented up to 60% of the Archaea sequences in this layer, have declined to <10%. Bacterial communities overall were less diverse after 2007, with a significant decrease of the Bacteroidetes. These significant shifts suggest that the microbial food webs are sensitive to physical oceanographic changes such as those occurring in the Canadian Arctic over the past decade.

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          Most cited references 89

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          Introducing mothur: open-source, platform-independent, community-supported software for describing and comparing microbial communities.

          mothur aims to be a comprehensive software package that allows users to use a single piece of software to analyze community sequence data. It builds upon previous tools to provide a flexible and powerful software package for analyzing sequencing data. As a case study, we used mothur to trim, screen, and align sequences; calculate distances; assign sequences to operational taxonomic units; and describe the alpha and beta diversity of eight marine samples previously characterized by pyrosequencing of 16S rRNA gene fragments. This analysis of more than 222,000 sequences was completed in less than 2 h with a laptop computer.
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            The Ribosomal Database Project: improved alignments and new tools for rRNA analysis

            The Ribosomal Database Project (RDP) provides researchers with quality-controlled bacterial and archaeal small subunit rRNA alignments and analysis tools. An improved alignment strategy uses the Infernal secondary structure aware aligner to provide a more consistent higher quality alignment and faster processing of user sequences. Substantial new analysis features include a new Pyrosequencing Pipeline that provides tools to support analysis of ultra high-throughput rRNA sequencing data. This pipeline offers a collection of tools that automate the data processing and simplify the computationally intensive analysis of large sequencing libraries. In addition, a new Taxomatic visualization tool allows rapid visualization of taxonomic inconsistencies and suggests corrections, and a new class Assignment Generator provides instructors with a lesson plan and individualized teaching materials. Details about RDP data and analytical functions can be found at http://rdp.cme.msu.edu/.
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              Microbial diversity in the deep sea and the underexplored "rare biosphere".

              The evolution of marine microbes over billions of years predicts that the composition of microbial communities should be much greater than the published estimates of a few thousand distinct kinds of microbes per liter of seawater. By adopting a massively parallel tag sequencing strategy, we show that bacterial communities of deep water masses of the North Atlantic and diffuse flow hydrothermal vents are one to two orders of magnitude more complex than previously reported for any microbial environment. A relatively small number of different populations dominate all samples, but thousands of low-abundance populations account for most of the observed phylogenetic diversity. This "rare biosphere" is very ancient and may represent a nearly inexhaustible source of genomic innovation. Members of the rare biosphere are highly divergent from each other and, at different times in earth's history, may have had a profound impact on shaping planetary processes.
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                Author and article information

                Affiliations
                [1 ]Québec-Océan, Département de Biologie, and Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
                [2 ]Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada
                [3 ]Fisheries and Oceans Canada, Institute of Ocean Sciences, Sidney, British Columbia, Canada
                Argonne National Laboratory, United States of America
                Author notes

                Conceived and designed the experiments: AMC CL. Performed the experiments: AMC CL JÉT. Analyzed the data: AMC CL JÉT WKWL ECC. Wrote the paper: AMC CL JÉT WKWL ECC.

                Contributors
                Role: Editor
                Journal
                PLoS One
                plos
                plosone
                PLoS ONE
                Public Library of Science (San Francisco, USA )
                1932-6203
                2011
                9 November 2011
                : 6
                : 11
                3212577
                22096583
                PONE-D-11-11420
                10.1371/journal.pone.0027492
                (Editor)
                Comeau et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
                Counts
                Pages: 12
                Categories
                Research Article
                Biology
                Ecology
                Biodiversity
                Community Ecology
                Conservation Science
                Marine Ecology
                Microbial Ecology
                Genomics
                Metagenomics
                Marine Biology
                Marine Conservation
                Marine Ecology
                Earth Sciences
                Atmospheric Science
                Climatology
                Climate Change
                Marine and Aquatic Sciences
                Oceanography
                Biological Oceanography
                Oceans
                Arctic Ocean
                Marine Ecology

                Uncategorized

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