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  • 1
    In: Marine Ecology, Wiley, Vol. 28 ( 2007-09-10), p. 169-177
    Materialart: Online-Ressource
    ISSN: 0173-9565
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2007
    ZDB Id: 2020745-1
    ZDB Id: 225578-9
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    In: Limnology and Oceanography: Methods, Wiley, Vol. 16, No. 6 ( 2018-06), p. 356-366
    Kurzfassung: Particulate organic carbon (POC) represents a small portion of total carbon in the ocean. However, it plays a large role in the turnover of organic matter through the biological pump and other processes. Early on since the development of the POC measurement technique in the 1960s, it was known that dissolved organic carbon (DOC) adsorbs and is retained both on and in the filter. That retained DOC is measured as if it was part of the particulate fraction, an artifact that can cause significant overestimates of POC concentration. We set out to address the long‐standing question of whether the magnitude of the DOC adsorption is affected by the quantity and quality of the dissolved organic matter in the sample. However, our results precluded an unequivocal answer to that question; nevertheless, the experimental data generated did allow us to develop and test predictive models that relate the mass of carbon adsorbed to the volume of sample filtered. The results indicate that the uptake of DOC can be predicted using an exponential model and that a saturation point is approached when approximately a half‐liter of water is filtered. This model can be a valuable tool for correcting existing POC data sets that did not account for DOC adsorption. Nonetheless, this approach should not be regarded as a substitute for collecting in situ filter blanks in parallel with POC samples to properly correct for this artifact.
    Materialart: Online-Ressource
    ISSN: 1541-5856 , 1541-5856
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2018
    ZDB Id: 2161715-6
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    In: Journal of Ecology, Wiley, Vol. 104, No. 6 ( 2016-11), p. 1682-1695
    Kurzfassung: Phytoplankton assemblages in the open ocean are usually assumed to be mixed on local scales unless large semi‐permanent density discontinuities separating water masses are present. Recent modelling studies have, however, suggested that ephemeral submesoscale oceanographic features leading to only subtle density discontinuities may be important for controlling phytoplankton alpha‐ and beta‐diversity patterns. Until now, no empirical evidence has been presented to support this hypothesis. Using hydrographic and taxonomic composition data collected near Iceland during the period of the 2008 spring bloom, we show that the distribution of phytoplankton alpha‐ and beta‐diversity was related to submesoscale heterogeneity in oceanographic conditions. Distinct phytoplankton communities as well as differences in richness were identified on either side of a front delimiting surface waters of slightly different (˜0.03) salinities. Alpha‐diversity was significantly higher on the high salinity side of the front compared to the low salinity side. This difference was primarily driven by the presence of several large diatom species in the high salinity region, especially of the genus Chaetoceros which dominated the biomass here. By investigating beta‐diversity in relation to environmental and spatiotemporal variables, we show that the regional distribution of phytoplankton taxa was influenced by both different environmental conditions on either side of the front and dispersal limitation across the front. Changes in beta‐diversity were primarily driven by turnover rather than nestedness and were apparently controlled by different processes in each region. Synthesis . This study shows that small‐scale and ephemeral density discontinuities created by submesoscale frontal dynamics can play a major role in structuring patterns of phytoplankton diversity. Evidence is presented that they can generate changes in environmental conditions (leading to environmental filtering) and act as physical (dispersal) barriers for phytoplankton transport. The study suggests that dispersal barriers are potentially of much greater importance for phytoplankton diversity at local scales than currently recognized and indicates that drivers of marine phytoplankton diversity are similar to those structuring diversity of land plants.
    Materialart: Online-Ressource
    ISSN: 0022-0477 , 1365-2745
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2016
    ZDB Id: 3023-5
    ZDB Id: 2004136-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    In: Limnology and Oceanography: Methods, Wiley, Vol. 18, No. 9 ( 2020-09), p. 516-530
    Kurzfassung: Holographic microscopy has emerged as a tool for in situ imaging of microscopic organisms and other particles in the marine environment: appealing because of the relatively larger sampling volume and simpler optical configuration compared to other imaging systems. However, its quantitative capabilities have so far remained uncertain, in part because hologram reconstruction and image recognition have required manual operation. Here, we assess the quantitative skill of our automated hologram processing pipeline (CCV Pipeline), to evaluate the size and concentration measurements of environmental and cultured assemblages of marine plankton particles, and microspheres. Over 1 million particles, ranging from 10 to 200  μ m in equivalent spherical diameter, imaged by the 4‐Deep HoloSea digital inline holographic microscope (DIHM) are analyzed. These measurements were collected in parallel with a FlowCam (FC), Imaging FlowCytobot (IFCB), and manual microscope identification. Once corrections for particle location and nonuniform illumination were developed and applied, the DIHM showed an underestimate in ESD of about 3% to 10%, but successfully reproduced the size spectral slope from environmental samples, and the size distribution of cultures ( Dunaliella tertiolecta , Heterosigma akashiwo , and Prorocentrum micans ) and microspheres. DIHM concentrations (order 1 to 1000 particles ml −1 ) showed a linear agreement ( r 2 = 0.73) with the other instruments, but individual comparisons at times had large uncertainty. Overall, we found the DIHM and the CCV Pipeline required extensive manual correction, but once corrected, provided concentration and size estimates comparable to the other imaging systems assessed in this study. Holographic cameras are mechanically simple, autonomous, can operate at very high pressures, and provide a larger sampling volume than comparable lens‐based tools. Thus, we anticipate that these characterization efforts will be rewarded with novel discovery in new oceanic environments.
    Materialart: Online-Ressource
    ISSN: 1541-5856 , 1541-5856
    URL: Issue
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2020
    ZDB Id: 2161715-6
    Standort Signatur Einschränkungen Verfügbarkeit
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