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  • 1
    Book
    Book
    Distribution and role of microprotozoa in the Southern Ocean : = Verteilung und Einfluß von herbivoren Protozoen auf Phytoplanktonbestände und Vertikalflüsse im Südpolarmeer (1997)
    Bremerhaven : Alfred-Wegener-Institut für Polar- und Meeresforschung
    Details Availability
    Keywords: Hochschulschrift ; Forschungsbericht ; Südpolarmeer ; Phytoplankton ; Zooplankton ; Antarktis ; Polarmeer ; Mikroplankton ; Wahrscheinlichkeitsverteilung ; Südpolarmeer ; Phytoplankton ; Zooplankton ; Antarktis ; Polarmeer ; Mikroplankton ; Wahrscheinlichkeitsverteilung ; Phytoplankton ; Südpolarmeer
    Type of Medium: Book
    Pages: 119 S. , graph. Darst.
    Series Statement: Berichte zur Polarforschung 253
    URL: http://www.gbv.de/dms/bs/toc/238836916.pdf
    URL: http://www.gbv.de/dms/bs/toc/238836916.pdf
    RVK:
    RZ 95507
    RVK:
    RY 20075
    Language: English
    Note: Literaturverz. S. 105 - 119 , Intermediärsprache: Deutsch , Teilw. zugl.: Bremen, Univ., Diss., 1996
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  • 2
    Electronic Resource
    Electronic Resource
    Ecosystem dynamics based on plankton functional types for global ocean biogeochemistry models (2005)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 11 (2005), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Ecosystem processes are important determinants of the biogeochemistry of the ocean, and they can be profoundly affected by changes in climate. Ocean models currently express ecosystem processes through empirically derived parameterizations that tightly link key geochemical tracers to ocean physics. The explicit inclusion of ecosystem processes in models will permit ecological changes to be taken into account, and will allow us to address several important questions, including the causes of observed glacial–interglacial changes in atmospheric trace gases and aerosols, and how the oceanic uptake of CO2 is likely to change in the future. There is an urgent need to assess our mechanistic understanding of the environmental factors that exert control over marine ecosystems, and to represent their natural complexity based on theoretical understanding. We present a prototype design for a Dynamic Green Ocean Model (DGOM) based on the identification of (a) key plankton functional types that need to be simulated explicitly to capture important biogeochemical processes in the ocean; (b) key processes controlling the growth and mortality of these functional types and hence their interactions; and (c) sources of information necessary to parameterize each of these processes within a modeling framework. We also develop a strategy for model evaluation, based on simulation of both past and present mean state and variability, and identify potential sources of validation data for each. Finally, we present a DGOM-based strategy for addressing key questions in ocean biogeochemistry. This paper thus presents ongoing work in ocean biogeochemical modeling, which, it is hoped will motivate international collaborations to improve our understanding of the role of the ocean in the climate system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.2005.1004.x
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    Paper (German National Licenses)
    Fulltext
  • 3
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    Deep carbon export from a Southern Ocean iron-fertilized diatom bloom (2012)
    Nature Publishing Group
    In:  Nature, 487 (7407). pp. 313-319.
    Details
    Publication Date: 2019-09-23
    Description: Fertilization of the ocean by adding iron compounds has induced diatom-dominated phytoplankton blooms accompanied by considerable carbon dioxide drawdown in the ocean surface layer. However, because the fate of bloom biomass could not be adequately resolved in these experiments, the timescales of carbon sequestration from the atmosphere are uncertain. Here we report the results of a five-week experiment carried out in the closed core of a vertically coherent, mesoscale eddy of the Antarctic Circumpolar Current, during which we tracked sinking particles from the surface to the deep-sea floor. A large diatom bloom peaked in the fourth week after fertilization. This was followed by mass mortality of several diatom species that formed rapidly sinking, mucilaginous aggregates of entangled cells and chains. Taken together, multiple lines of evidence—although each with important uncertainties—lead us to conclude that at least half the bloom biomass sank far below a depth of 1,000 metres and that a substantial portion is likely to have reached the sea floor. Thus, iron-fertilized diatom blooms may sequester carbon for timescales of centuries in ocean bottom water and for longer in the sediments.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Format: text
    DOI: 10.1038/nature11229
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Total alkalinity: The explicit conservative expression and its application to biogeochemical processes (2007)
    Elsevier
    In:  Marine Chemistry, 106 . pp. 287-300.
    Details
    Publication Date: 2017-08-22
    Description: Total alkalinity (TA) is one of the few measurable quantities that can be used together with other quantities to calculate concentrations of species of the carbonate system (CO2, HCO3 −, CO32−, H+, OH−). TA and dissolved inorganic carbon (DIC) are conservative quantities with respect to mixing and changes in temperature and pressure and are, therefore, used in oceanic carbon cycle models. Thus it is important to understand the changes of TA due to various biogeochemical processes such as formation and remineralization of organic matter by microalgae, precipitation and dissolution of calcium carbonate. Unfortunately deriving such changes from the common expression for TA in terms of concentrations of on-conservative chemical species (HCO3 −, CO3 2 −, B(OH)4 −, H+, OH−, etc.) is rarely obvious. Here an expression for TA (TAec) in terms of the total concentrations of certain major ions (Na+, Cl−, Ca2+ etc.) and the total concentrations of various acid-base species (total phosphate etc.) is derived from Dickson's original definition of TA under the constraint of electroneutrality. Changes of TA by various biogeochemical processes are easy to derive from this so-called explicit conservative expression for TA because each term in this expression is independent of changes of temperature or pressure within the ranges normally encountered in the ocean and obeys a linear mixing relation. Further, the constrains of electroneutrality for nutrient uptake by microalgae and photoautotrophs are discussed. A so-called nutrient-H+-compensation principle is proposed. This principle in combination with TAec allows one to make predictions for changes in TA due to uptake of nutrients that are consistent with observations. A new prediction based on this principle is the change in TA due to nitrogen fixation followed by remineralization of organic matter and subsequent nitrification of ammonia which implies a significant sink of TA in tropical and subtropical regions where most of the nitrogen fixation takes place.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.marchem.2007.01.006
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Mesoscale features create hotspots of carbon uptake in the Antarctic Circumpolar Current (2017)
    Elsevier
    In:  Deep Sea Research Part II: Topical Studies in Oceanography, 138 . pp. 39-51.
    Details
    Publication Date: 2020-02-06
    Description: The influence of eddy structures on the seasonal depletion of dissolved inorganic carbon (DIC) and carbon dioxide (CO2) disequilibrium was investigated during a trans-Atlantic crossing of the Antarctic Circumpolar Current (ACC) in austral summer 2012. The Georgia Basin, downstream of the island of South Georgia (54-55°S, 36-38°W) is a highly dynamic region due to the mesoscale activity associated with the flow of the Subantarctic Front (SAF) and Polar Front (PF). Satellite sea-surface height and chlorophyll-a anomalies revealed a cyclonic cold core that dominated the northern Georgia Basin that was formed from a large meander of the PF. Warmer waters influenced by the SAF formed a smaller anticyclonic structure to the east of the basin. Both the cold core and warm core eddy structures were hotspots of carbon uptake relative to the rest of the ACC section during austral summer. This was most amplified in the cold core where greatest CO2 undersaturation (−78 μatm) and substantial surface ocean DIC deficit (5.1 mol m−2) occurred. In the presence of high wind speeds, the cold core eddy acted as a strong sink for atmospheric CO2 of 25.5 mmol m−2 day−1. Waters of the warm core displayed characteristics of the Polar Frontal Zone (PFZ), with warmer upper ocean waters and enhanced CO2 undersaturation (−59 μatm) and depletion of DIC (4.9mol m−2). A proposed mechanism for the enhanced carbon uptake across both eddy structures is based on the Ekman eddy pumping theory: (i) the cold core is seeded with productive (high chlorophyll-a) waters from the Antarctic Zone and sustained biological productivity through upwelled nutrient supply that counteracts DIC inputs from deep waters; (ii) horizontal entrainment of low-DIC surface waters (biological uptake) from the PFZ downwell within the warm core and cause relative DIC-depletion in the upper water column. The observations suggest that the formation and northward propagation of cold core eddies in the region of the PF could project low-DIC waters towards the site of Antarctic Intermediate Water formation and enhance CO2 drawdown into the deep ocean.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1016/j.dsr2.2015.10.006
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Data base on pelagic ciliates grazing and growth rate as a function of size, prey size and type compiled from the literature (2011)
    PANGAEA
    In:  Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven
    Details
    Publication Date: 2023-03-16
    Description: Microzooplankton (the 20 to 200 µm size class of zooplankton) is recognised as an important part of marine pelagic ecosystems. In terms of biomass and abundance pelagic ciliates are one of the important groups of organism in microzooplankton. However, their rates - grazing and growth - , feeding behaviour and prey preferences are poorly known and understood. A set of data was assembled in order to derive a better understanding of pelagic ciliates rates, in response to parameters such as prey concentration, prey type (size and species), temperature and their own size. With these objectives, literature was searched for laboratory experiments with information on one or more of these parameters effect studied. The criteria for selection and inclusion in the database included: (i) controlled laboratory experiment with a known ciliates feeding on a known prey; (ii) presence of ancillary information about experimental conditions, used organisms - cell volume, cell dimensions, and carbon content. Rates and ancillary information were measured in units that meet the experimenter need, creating a need to harmonize the data units after collection. In addition different units can link to different mechanisms (carbon to nutritive quality of the prey, volume to size limits). As a result, grazing rates are thus available as pg C/(ciliate*h), µm**3/(ciliate*h) and prey cell/(ciliate*h); clearance rate was calculated if not given and growth rate is expressed as the growth rate per day.
    Keywords: EUR-OCEANS; European network of excellence for Ocean Ecosystems Analysis
    Type: Dataset
    Format: application/zip, 1.4 MBytes
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    DATA PANGAEA
  • 7
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    Particulate Thorium-234 (Th-234), organic carbon (POC) and organic nitrogen (PON) concentrations using in-situ pumps (particles 〉53 µm) during POLARSTERN cruise ANT-XXVIII/3 (2015)
    PANGAEA
    Details
    Publication Date: 2023-03-16
    Keywords: ANT-XXVIII/3; AWI_MarGeoChem; Carbon, organic, particulate; Carbon, organic, particulate/Thorium-234 ratio; Carbon, organic, particulate/Thorium-234 ratio, standard deviation; Date/Time of event; DEPTH, water; Elevation of event; Event label; In situ pump; ISP; Latitude of event; Longitude of event; Marine Geochemistry @ AWI; Nitrogen, organic, particulate; Nitrogen, organic, particulate/Thorium-234 ratio; Nitrogen, organic, particulate/Thorium-234 ratio, standard deviation; Polarstern; PS79; PS79/057-5; PS79/069-4; PS79/081-3; PS79/084-11; PS79/091-10; PS79/139-13; PS79/174-17; South Atlantic Ocean; Thorium-234, particulate; Thorium-234, particulate, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 154 data points
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    DATA PANGAEA
  • 8
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    POC/Th-234 and PON/Th-234 ratios, POC and PON export fluxes measured with sediment traps during POLARSTERN cruise ANT-XXVIII/3 (2015)
    PANGAEA
    Details
    Publication Date: 2023-03-16
    Keywords: ANT-XXVIII/3; AWI_MarGeoChem; Carbon, organic, particulate, flux; Carbon, organic, particulate/Thorium-234 ratio; Carbon, organic, particulate/Thorium-234 ratio, standard deviation; Date/Time of event; DEPTH, water; Duration; Elevation of event; Event label; Latitude of event; Longitude of event; Marine Geochemistry @ AWI; Nitrogen, organic, particulate, flux; Nitrogen, organic, particulate/Thorium-234 ratio; Nitrogen, organic, particulate/Thorium-234 ratio, standard deviation; Polarstern; PS79; PS79/086-4; PS79/087-1; PS79/091-3; PS79/098-1; PS79/100-1; PS79/114-1; PS79/128-12; PS79/136-11; PS79/137-1; PS79/139-1; PS79/140-1; South Atlantic Ocean; Trap, sediment; TRAPS
    Type: Dataset
    Format: text/tab-separated-values, 139 data points
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    DATA PANGAEA
  • 9
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    Data base on heterotrophic dinoflagellates grazing and growth rate as a function of size, prey size and type compiled from the literature (2011)
    PANGAEA
    In:  Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven
    Details
    Publication Date: 2023-03-16
    Description: Microzooplankton (the 20 to 200 µm size class of zooplankton) is recognised as an important part of marine pelagic ecosystems. In terms of biomass and abundance heterotrophic dinoflagellates are one of the important groups of organism in microzooplankton. However, their rates - grazing and growth - , feeding behaviour and prey preferences are poorly known and understood. A set of data was assembled in order to derive a better understanding of heterotrophic dinoflagellates rates, in response to parameters such as prey concentration, prey type (size and species), temperature and their own size. With these objectives, literature was searched for laboratory experiments with information on one or more of these parameters effect studied. The criteria for selection and inclusion in the database included: (i) controlled laboratory experiment with a known dinoflagellate feeding on a known prey; (ii) presence of ancillary information about experimental conditions, used organisms - cell volume, cell dimensions, and carbon content. Rates and ancillary information were measured in units that meet the experimenter need, creating a need to harmonize the data units after collection. In addition different units can link to different mechanisms (carbon to nutritive quality of the prey, volume to size limits). As a result, grazing rates are thus available as pg C dinoflagellate-1 h-1, µm3 dinoflagellate-1 h-1 and prey cell dinoflagellate-1 h-1; clearance rate was calculated if not given and growth rate is expressed as the growth rate per day.
    Keywords: EUR-OCEANS; European network of excellence for Ocean Ecosystems Analysis
    Type: Dataset
    Format: application/zip, 425.4 kBytes
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    DATA PANGAEA
  • 10
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    Abundance and biomass of protozooplankton from the iron-induced phytoplankton bloom during the EisenEx experiment in 2000 in the Southern Ocean (2006)
    PANGAEA
    In:  Supplement to: Henjes, Joachim; Assmy, Philipp; Klaas, Christine; Smetacek, Victor (2007): Response of the larger protozooplankton to an iron-induced phytoplankton bloom in the Polar Frontal Zone of the Southern Ocean (EisenEx). Deep Sea Research Part I: Oceanographic Research Papers, 54(5), 774-791, https://doi.org/10.1016/j.dsr.2007.02.005
    Details
    Publication Date: 2023-03-16
    Description: The responses of larger (〉50 µm in diameter) protozooplankton groups to a phytoplankton bloom induced by in situ iron fertilization (EisenEx) in the Polar Frontal Zone (PFZ) of the Southern Ocean in austral spring are presented. During the 21 days of the experiment, samples were collected from seven discrete depths in the upper 150 m inside and outside the fertilized patch for the enumeration of acantharia, foraminifera, radiolaria, heliozoa, tintinnid ciliates and aplastidic thecate dinoflagellates. Inside the patch, acantharian numbers increased twofold, but only negligibly in surrounding waters. This finding is of major interest, since acantharia are suggested to be involved in the formation of barite (BaSO_4 ) found in sediments and which is a palaeoindicator of both ancient and modern high productivity regimes. Foraminifera increased significantly in abundance inside and outside the fertilized patch. However the marked increase of juveniles after a full moon event suggests a lunar periodicity in the reproduction cycle of some foraminiferan species rather than a reproductive response to enhanced food availability. In contrast, adult radiolaria showed no clear trend during the experiment, but juveniles increased threefold indicating elevated reproduction. Aplastidic thecate dinoflagellates almost doubled in numbers and biomass, but also increased outside the patch. Tintinnid numbers decreased twofold, although biomass remained constant due to a shift in the size spectrum. Empty tintinnid loricae, however, increased by a factor of two indicating that grazing pressure on this group mainly by copepods intensified during EisenEx. The results show that iron-fertilization experiments can shed light on the biology and the role of these larger protists in pelagic ecosystem which will improve their use as proxies in palaeoceanography.
    Keywords: ANT-XVIII/2; CTD/Rosette; CTD11; CTD118; CTD121; CTD125; CTD130; CTD146; CTD15; CTD150; CTD19; CTD47; CTD52; CTD55; CTD58; CTD64; CTD67; CTD71; CTD75; CTD88; CTD-RO; EisenEx; European Iron Enrichment Experiment in the Southern Ocean; Polarstern; PS58/009-6; PS58/011-3; PS58/012-4; PS58/014-6; PS58/038-7; PS58/041-5; PS58/042-5; PS58/043-4; PS58/045-9; PS58/046-5; PS58/048-5; PS58/049-5; PS58/061-3; PS58/088-7; PS58/090-2; PS58/091-3; PS58/092-6; PS58/107-6; PS58/108-3; PS58 EISENEX; South Atlantic
    Type: Dataset
    Format: application/zip, 38 datasets
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    DATA PANGAEA
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