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  • 1
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    In situ imaging reveals the biomass of giant protists in the global ocean (2016)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2016-04-21
    Description: Planktonic organisms play crucial roles in oceanic food webs and global biogeochemical cycles. Most of our knowledge about the ecological impact of large zooplankton stems from research on abundant and robust crustaceans, and in particular copepods. A number of the other organisms that comprise planktonic communities are fragile, and therefore hard to sample and quantify, meaning that their abundances and effects on oceanic ecosystems are poorly understood. Here, using data from a worldwide in situ imaging survey of plankton larger than 600 mum, we show that a substantial part of the biomass of this size fraction consists of giant protists belonging to the Rhizaria, a super-group of mostly fragile unicellular marine organisms that includes the taxa Phaeodaria and Radiolaria (for example, orders Collodaria and Acantharia). Globally, we estimate that rhizarians in the top 200 m of world oceans represent a standing stock of 0.089 Pg carbon, equivalent to 5.2% of the total oceanic biota carbon reservoir. In the vast oligotrophic intertropical open oceans, rhizarian biomass is estimated to be equivalent to that of all other mesozooplankton (plankton in the size range 0.2-20 mm). The photosymbiotic association of many rhizarians with microalgae may be an important factor in explaining their distribution. The previously overlooked importance of these giant protists across the widest ecosystem on the planet changes our understanding of marine planktonic ecosystems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Biard, Tristan -- Stemmann, Lars -- Picheral, Marc -- Mayot, Nicolas -- Vandromme, Pieter -- Hauss, Helena -- Gorsky, Gabriel -- Guidi, Lionel -- Kiko, Rainer -- Not, Fabrice -- England -- Nature. 2016 Apr 28;532(7600):504-7. doi: 10.1038/nature17652. Epub 2016 Apr 20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Sorbonne Universites, UPMC Universite Paris 06, CNRS, Laboratoire Adaptation et Diversite en Milieu Marin UMR7144, Station Biologique de Roscoff, 29688 Roscoff, France. ; Sorbonne Universites, UPMC Universite Paris 06, CNRS, Laboratoire d'Oceanographie de Villefranche (LOV) UMR7093, Observatoire Oceanologique, 06230 Villefranche-sur-Mer, France. ; GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstrasse 1-3, 24148 Kiel, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27096373" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biomass ; *Biota ; Carbon/metabolism ; Carbon Sequestration ; Earth (Planet) ; Microalgae/metabolism ; *Oceans and Seas ; Photosynthesis ; Rhizaria/classification/*isolation & purification/metabolism ; Seawater/chemistry ; Symbiosis ; Zooplankton/classification/*isolation & purification/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    Springtime zooplankton size structure over the continental shelf of the Bay of Biscay (2014)
    Copernicus
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    Publication Date: 2014-10-16
    Description: Linking lower and higher trophic levels requires special focus on the essential role played by mid-trophic levels, i.e., the zooplankton. One of the most relevant pieces of information regarding zooplankton in terms of flux of energy lies in its size structure. In this study, an extensive data set of size measurements is presented, covering parts of the western European continental shelf and slope, from the Galician coast to the Ushant front, during the springs from 2005 to 2012. Zooplankton size spectra were estimated using measurements carried out in situ with the Laser Optical Plankton Counter (LOPC) and with an image analysis of WP2 net samples (200 μm mesh size) performed following the ZooScan methodology. The LOPC counts and sizes particles within 100–2000 μm of spherical equivalent diameter (ESD), whereas the WP2/ZooScan allows for counting, sizing and identification of zooplankton from ~ 400 μm ESD. The difference between the LOPC (all particles) and the WP2/ZooScan (zooplankton only) was assumed to provide the size distribution of non-living particles, whose descriptors were related to a set of explanatory variables (including physical, biological and geographic descriptors). A statistical correction based on these explanatory variables was further applied to the LOPC size distribution in order to remove the non-living particles part, and therefore estimate the size distribution of zooplankton. This extensive data set provides relevant information about the zooplankton size distribution variability, productivity and trophic transfer efficiency in the pelagic ecosystem of the Bay of Biscay at a regional and interannual scale.
    Print ISSN: 1812-0784
    Electronic ISSN: 1812-0792
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 3
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    Spring-time zooplankton size structure over the continental shelf of the Bay of Biscay (2013)
    Copernicus
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    Publication Date: 2013-11-29
    Description: Linking lower to higher trophic levels requires a special focus on the pivotal role played by mid-trophic levels, i.e. the zooplankton. One of the most relevant information on zooplankton in term of fluxes of matter lies in its size structure. We present here an extensive dataset of size measurements covering part of the western European shelf and slope, from the Galician coast to the Ushant front, during springs from 2005 to 2012. Zooplankton size spectra were estimated using both measurements carried out in situ by the Laser-Optical Plankton Counter (LOPC, 816 records) and WP2 net (200 μm mesh size) samples scanned following the ZooScan methodology and image analysis (a total of 89 samples were analyzed). The LOPC counts and sizes all particles in the range 100 to 2000 μm of spherical equivalent diameter (ESD) whereas the WP2/ZooScan allows the counting, sizing and identification of zooplankton from ~400 μm ESD. The difference between the LOPC (all particles) and the WP2/ZooScan (zooplankton only) is assumed to provide the size distribution of non-living particles whose descriptors are further related to a set of explanatory variables (including physical, biological and geographic descriptors). A statistical correction based on these explanatory variables is then applied to LOPC measurements to removed the part due to non-living particles and estimate zooplankton size spectra. This extensive data set provides a new look at regional and inter-annual variability of the pelagic ecosystem of the Bay of Biscay.
    Print ISSN: 1812-0806
    Electronic ISSN: 1812-0822
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 4
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    Zooplankton communities fluctuations from 1995 to 2005 in the Bay of Villefranche-sur-Mer (Northern Ligurian Sea, France) (2010)
    Copernicus
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    Publication Date: 2010-12-15
    Description: An integrated analysis of the pelagic ecosystems of the Ligurian Sea is performed combining time series of different zooplankton groups (small and large copepods, chaetognaths, appendicularians, pteropods, thaliaceans, decapods larvae, other crustaceans, other gelatinous and other zooplankton), chlorophyll-a and nutrients, seawater salinity, temperature and density and local weather at the Point B coastal station (Northern Ligurian Sea). From January 1995 to December 2005, a shift in most variables occurred ca. 2000. From 1995 to 2000 winters were wet and mild resulting in lower winter sea surface density. These years showed lower than average nutrients and zooplankton concentrations while phytoplankton biomass was higher. After 2000, winters were colder and dryer resulting in higher sea surface density. Nutrients and zooplankton showed higher concentrations while phytoplankton was lower than average. The ca. 2000 shift was observed for most zooplankton groups with a one year delay for certain groups. The observed patterns suggest that the pelagic ecosystem trophic state is mostly set by the winter forcing on the convection that upwells nutrients to the surface sustaining the spring bloom. However, low phytoplankton concentrations in higher nitrate and zooplankton conditions during the well mixed years suggest that phytoplankton is controlled by grazers. The proposed mechanisms of convection regimes hold for most of the time series, but specific years with contradicting patterns needed to be explained by other factors. The limitation of phytoplankton growth by the light availability in spring/summer was then proposed as a secondary driving force that can moderate or even reverse the winter forcing. Finally, the eleven years of observation did not reveal a clear link with the North Atlantic Oscillation, suggesting a more complex dynamics linking large scale climate to Ligurian Sea ecosystems or that the length of the plankton monitoring is not yet sufficient to detect those links.
    Print ISSN: 1810-6277
    Electronic ISSN: 1810-6285
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 5
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    Inter-annual fluctuations of zooplankton communities in the Bay of Villefranche-sur-mer from 1995 to 2005 (Northern Ligurian Sea, France) (2011)
    Copernicus
    Details
    Publication Date: 2011-11-07
    Description: An integrated analysis of the pelagic ecosystems of the Ligurian Sea is performed combining time series (1995–2005) of several zooplankton groups (one group for copepods smaller than 0.724 mm3 and nine groups for individuals larger than 0.724 mm3, i.e. large copepods, decapod larvæ, other crustaceans, chaetognaths, appendicularians, pteropods, thaliaceans, gelatinous predators and other zooplankton), chlorophyll-a, nutrients, salinity, temperature, density, and local weather at Point B coastal station (Northern Ligurian Sea). From 1995 to 2000 winters were wet and mild resulting in lower winter sea surface density. These years showed lower than average nutrients and zooplankton concentrations while chlorophyll-a biomass was high. After 2000, winters were colder and dryer resulting in higher sea surface density. Nutrients and zooplankton showed higher concentrations while chlorophyll-a was lower than average. The ca. 2000 change was observed for most zooplankton groups with a one-year delay for some groups. Inter-annual variability within each period was also observed. The observed patterns suggest that the pelagic ecosystem trophic state at the studied point is mostly set by the winter forcing on the vertical mixing that upwells nutrients to the surface sustaining primary production. Surprisingly, low chlorophyll-a biomass in high nitrate and zooplankton conditions during the well mixed years suggest that phytoplankton biomass is controlled by grazers. The proposed mechanisms of stronger winter vertical mixing hold for most of the time series, but specific years with contradicting patterns suggest also the possible influence of the summer climate. A review of recent literature suggests that changes in the pelagic ecosystem are not limited to the studied site but concern also the central Ligurian Sea.
    Print ISSN: 1726-4170
    Electronic ISSN: 1726-4189
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 6
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    A non-diatom plankton bloom controlled by copepod grazing and amphipod predation: Preliminary results from the LOHAFEX iron-fertilisation experiment. (2009)
    In:  EPIC3GLOBEC International NewsletterOctober, 15(2), pp. 3-6
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , notRev
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