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  • Computer-simulated concentration profiles; File format; File name; File size; Microsensor concentration profiles; Uniform resource locator/link to file  (1)
  • Microbial ecology  (1)
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  • 1
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    PANGAEA
    In:  Supplement to: Klawonn, Isabell; Eichner, Meri J; Wilson, Samuel T; Moradi, Nasrollah; Thamdrup, Bo; Kümmel, Steffen; Gehre, Matthias; Khalili, Arzhang; Grossart, Hans-Peter; Karl, David Michael; Ploug, Helle (2020): Distinct nitrogen cycling and steep chemical gradients in Trichodesmium colonies. The ISME Journal, 14(2), 399-412, https://doi.org/10.1038/s41396-019-0514-9
    Publication Date: 2023-01-13
    Description: Trichodesmium is an important dinitrogen (N~2~)-fixing cyanobacterium in marine ecosystems. Recent nucleic acid analyses indicate that Trichodesmium colonies with their diverse epibionts support various nitrogen (N) transformations beyond N~2~-fixation. However, rates of these transformations and concentration gradients of N-compounds in Trichodesmium colonies remain largely unresolved. We combined isotope-tracer incubations, micro-profiling, and numeric modelling to explore carbon fixation, N-cycling processes, as well as oxygen, ammonium and nitrate concentration gradients in individual field-sampled Trichodesmium colonies. Colonies were net-autotrophic, with carbon and N~2~-fixation occurring mostly at day-time. Ten percent of the fixed N was released as ammonium after 12-hour incubations. Nitrification was not detectable but nitrate consumption was high when nitrate was added. The consumed nitrate was partly reduced to ammonium, while denitrification was insignificant. Thus, the potential N-transformation network was characterized by fixed N gain and recycling processes rather than denitrification. Oxygen concentrations within colonies were 60–200% air-saturation. Moreover, our modelling predicted steep concentration gradients, with up to 6-fold higher ammonium concentrations, and nitrate depletion in the colony centre compared to the ambient seawater. These gradients created a chemically heterogeneous microenvironment, presumably facilitating diverse microbial metabolisms in millimetre-sized Trichodesmium colonies.
    Keywords: Computer-simulated concentration profiles; File format; File name; File size; Microsensor concentration profiles; Uniform resource locator/link to file
    Type: Dataset
    Format: text/tab-separated-values, 12 data points
    Location Call Number Limitation Availability
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  • 2
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 29 (2015): 1145–1164, doi:10.1002/2015GB005141.
    Description: Time-series observations are critical to understand the structure, function, and dynamics of marine ecosystems. The Hawaii Ocean Time-series program has maintained near-monthly sampling at Station ALOHA (22°45′N, 158°00′W) in the oligotrophic North Pacific Subtropical Gyre (NPSG) since 1988 and has identified ecosystem variability over seasonal to interannual timescales. To further extend the temporal resolution of these near-monthly time-series observations, an extensive field campaign was conducted during July–September 2012 at Station ALOHA with near-daily sampling of upper water-column biogeochemistry, phytoplankton abundance, and activity. The resulting data set provided biogeochemical measurements at high temporal resolution and documents two important events at Station ALOHA: (1) a prolonged period of low productivity when net community production in the mixed layer shifted to a net heterotrophic state and (2) detection of a distinct sea-surface salinity minimum feature which was prominent in the upper water column (0–50 m) for a period of approximately 30 days. The shipboard observations during July–September 2012 were supplemented with in situ measurements provided by Seagliders, profiling floats, and remote satellite observations that together revealed the extent of the low productivity and the sea-surface salinity minimum feature in the NPSG.
    Description: NOAA Climate Observation Division; National Science Foundation (NSF) Center for Microbial Oceanography: Research and Education (C-MORE) Grant Numbers: EF0424599, OCE-1153656, OCE-1260164; Gordon and Betty Moore Foundation Marine Microbiology Investigator
    Description: 2016-02-13
    Keywords: Primary productivity ; Microbial ecology ; Station ALOHA ; Temporal variability ; Biogeochemistry
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Format: application/msword
    Location Call Number Limitation Availability
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