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  1. Thesis ; Online: Auswirkungen der Nährstoffstöchiometrie auf die Quanität und Zusammensetzung von Alkenonen der Coccolithophoride Emiliania huxleyi

    Febiri, Sarah

    2008  

    Abstract: Um den Einfluss von Nitrat- und Phosphatlimitationen auf den Zellgehalt und die Zusammensetzung der Alkenone von E. huxleyi zu untersuchen, wurden in vier Ansätzen unterschiedlichen Nährstoffkonzentrationen eingestellt und ein vollständiger Blütenverlauf ...

    Abstract Um den Einfluss von Nitrat- und Phosphatlimitationen auf den Zellgehalt und die Zusammensetzung der Alkenone von E. huxleyi zu untersuchen, wurden in vier Ansätzen unterschiedlichen Nährstoffkonzentrationen eingestellt und ein vollständiger Blütenverlauf von E. huxleyi beprobt. Es konnte gezeigt werden, dass Nitrat- und Phosphatlimitation zwar einen gleichen Effekt auf den Gehalt und die Zusammensetzung der Alkenone in E. huxleyi haben, sich jedoch in der Stärke ihrer Auswirkungen unterscheiden. So akkumulierten die Alkenone bei beiden Limitationen, aber unter Nitratlimitation fiel diese Anreicherung geringer aus als unter Phosphatlimitation. Vermutlich verursachten Energielimitation und eine gehemmte Proteinbiosynthese und damit eine geringere Anzahl an alkenonsynthetisierenden Enzymen, diese geringere Akkumulation unter Nitratmangel. Ferner konnte beobachtet werden, dass sich im Blütenverlauf die Zusammensetzung hin zu längerkettigen und ungesättigteren Alkenonen veränderte. Alkenone im Allgemeinen dienen höchstwahrscheinlich als metabolische Speichermoleküle. Längerkettige Alkenone im besonderen, könnten zusätzlich eine Art Senke für überschüssigen photosynthtetischen Kohlenstoff während der stationären Phase darstellen. Die Änderungen in der Zusammensetzung bzw. die Zunahme stärker untersättigter Alkenone bewirkte eine Abnahme des UK37-lndex und dadurch eine niedrigere berechnete Inkubationstemperatur als tatsächlich vorlag. Dieser Einfluss der Nährstofflimitationen auf das Temperatursignal der Alkenone widerlegt jedoch nicht die Eignung des UK37-lndex als Paläo-SST-Proxy. Sie sollte jedoch bei abweichenden Ergebnissen von der globalen UK37-SST-Kalibrierung bedacht werden.
    Subject code 550
    Language German
    Publishing country de
    Document type Thesis ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article: An approach for particle sinking velocity measurements in the 3–400 μm size range and considerations on the effect of temperature on sinking rates

    Bach, Lennart Thomas / Riebesell, Ulf / Sett, Scarlett / Febiri, Sarah / Rzepka, Paul / Schulz, Kai Georg

    Marine biology. 2012 Aug., v. 159, no. 8

    2012  

    Abstract: The flux of organic particles below the mixed layer is one major pathway of carbon from the surface into the deep ocean. The magnitude of this export flux depends on two major processes—remineralization rates and sinking velocities. Here, we present an ... ...

    Abstract The flux of organic particles below the mixed layer is one major pathway of carbon from the surface into the deep ocean. The magnitude of this export flux depends on two major processes—remineralization rates and sinking velocities. Here, we present an efficient method to measure sinking velocities of particles in the size range from approximately 3–400 μm by means of video microscopy (FlowCAM®). The method allows rapid measurement and automated analysis of mixed samples and was tested with polystyrene beads, different phytoplankton species, and sediment trap material. Sinking velocities of polystyrene beads were close to theoretical values calculated from Stokes’ Law. Sinking velocities of the investigated phytoplankton species were in reasonable agreement with published literature values and sinking velocities of material collected in sediment trap increased with particle size. Temperature had a strong effect on sinking velocities due to its influence on seawater viscosity and density. An increase in 9 °C led to a measured increase in sinking velocities of ~40 %. According to this temperature effect, an average temperature increase in 2 °C as projected for the sea surface by the end of this century could increase sinking velocities by about 6 % which might have feedbacks on carbon export into the deep ocean.
    Keywords carbon ; microscopy ; oceans ; particle size ; phytoplankton ; polystyrenes ; rapid methods ; seawater ; sediments ; temperature ; traps ; viscosity
    Language English
    Dates of publication 2012-08
    Size p. 1853-1864.
    Publishing place Springer-Verlag
    Document type Article
    ZDB-ID 1117-4
    ISSN 1432-1793 ; 0025-3162
    ISSN (online) 1432-1793
    ISSN 0025-3162
    DOI 10.1007/s00227-012-1945-2
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

    Z 4' 69/153: Show issues

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  3. Article: An approach for particle sinking velocity measurements in the 3-400 μm size range and considerations on the effect of temperature on sinking rates.

    Bach, Lennart Thomas / Riebesell, Ulf / Sett, Scarlett / Febiri, Sarah / Rzepka, Paul / Schulz, Kai Georg

    Marine biology

    2012  Volume 159, Issue 8, Page(s) 1853–1864

    Abstract: The flux of organic particles below the mixed layer is one major pathway of carbon from the surface into the deep ocean. The magnitude of this export flux depends on two major processes-remineralization rates and sinking velocities. Here, we present an ... ...

    Abstract The flux of organic particles below the mixed layer is one major pathway of carbon from the surface into the deep ocean. The magnitude of this export flux depends on two major processes-remineralization rates and sinking velocities. Here, we present an efficient method to measure sinking velocities of particles in the size range from approximately 3-400 μm by means of video microscopy (FlowCAM
    Language English
    Publishing date 2012-05-22
    Publishing country Germany
    Document type Review
    ZDB-ID 1117-4
    ISSN 1432-1793 ; 0025-3162
    ISSN (online) 1432-1793
    ISSN 0025-3162
    DOI 10.1007/s00227-012-1945-2
    Database MEDical Literature Analysis and Retrieval System OnLINE

    Full text online

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    In stock of ZB MED Bonn / Germany

    Z 4' 69/153: Show issues

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

    Inter-library loan at ZB MED

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  4. Article ; Online: Photoacclimation to abrupt changes in light intensity by Phaeodactylum tricornutum and Emiliania huxleyi

    Barcelos e Ramos, Joana / Schulz, Kai G. / Febiri, Sarah / Riebesell, Ulf

    the role of calcification

    2012  

    Abstract: Phytoplankton experience strong and abrupt variations in light intensity. How cells cope with these changes influences their competitiveness in a highly dynamical environment. While a considerable amount of work has focused on photoacclimation, it is ... ...

    Abstract Phytoplankton experience strong and abrupt variations in light intensity. How cells cope with these changes influences their competitiveness in a highly dynamical environment. While a considerable amount of work has focused on photoacclimation, it is still unknown whether processes specific of phytoplankton groups (e.g. calcification and silicification) influence their response to changing light. Here we show that the diatom Phaeodactylum tricornutum and the coccolithophore Emiliania huxleyi respond to an abrupt increase in irradiance by increasing carbon fixation rates, decreasing light absorption through the decrease of light-harvesting pigments and increasing energy dissipation through the xanthophyll cycle. In addition, E. huxleyi rapidly increases calcium carbonate precipitation in response to elevated light intensity, thereby providing an additional sink for excess energy. Differences between the 2 species also emerge with regard to the magnitude and timing of their individual responses. While E. huxleyi show a pronounced decrease in chlorophyll a and fucoxanthin cellular contents following increased light intensity, P. tricornutum has a faster increase in diadinoxanthin quota, a slower decrease in Fv/Fm (ratio of variable to maximum fluorescence) and a stronger increase in organic carbon fixation rate during the first 10 min. Our findings provide further evidence of species-specific responses to abrupt changes in light intensity, which may partly depend on the phytoplankton functional groups, with coccolithophores having a supplementary path (calcification) for the rapid dissipation of excess energy produced after an abrupt increase in light intensity. These differences might influence competition between coexisting species and may therefore have consequences at the community level.
    Subject code 580
    Language English
    Publisher Inter Research
    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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    Inter-library loan at ZB MED

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  5. Article ; Online: An approach for particle sinking velocity measurements in the 3–400 μm size range and considerations on the effect of temperature on sinking rates

    Bach, Lennart T. / Riebesell, Ulf / Sett, Scarlett / Febiri, Sarah / Rzepka, Paul / Schulz, Kai G.

    2012  

    Abstract: The flux of organic particles below the mixed layer is one major pathway of carbon from the surface into the deep ocean. The magnitude of this export flux depends on two major processes—remineralization rates and sinking velocities. Here, we present an ... ...

    Abstract The flux of organic particles below the mixed layer is one major pathway of carbon from the surface into the deep ocean. The magnitude of this export flux depends on two major processes—remineralization rates and sinking velocities. Here, we present an efficient method to measure sinking velocities of particles in the size range from approximately 3–400 μm by means of video microscopy (FlowCAM®). The method allows rapid measurement and automated analysis of mixed samples and was tested with polystyrene beads, different phytoplankton species, and sediment trap material. Sinking velocities of polystyrene beads were close to theoretical values calculated from Stokes’ Law. Sinking velocities of the investigated phytoplankton species were in reasonable agreement with published literature values and sinking velocities of material collected in sediment trap increased with particle size. Temperature had a strong effect on sinking velocities due to its influence on seawater viscosity and density. An increase in 9 °C led to a measured increase in sinking velocities of ~40 %. According to this temperature effect, an average temperature increase in 2 °C as projected for the sea surface by the end of this century could increase sinking velocities by about 6 % which might have feedbacks on carbon export into the deep ocean.
    Subject code 551
    Language English
    Publisher Springer
    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  6. Conference proceedings ; Online: Trends of temperature and salintiy of the Baltic Sea for the period 1969-2005 and long-term variability of winter water mass formation

    Lehmann, Andreas / Hinrichsen, Hans-Harald / Febiri, Sarah / Tschersich, G.

    2007  

    Publishing country de
    Document type Conference proceedings ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  7. Article: An approach for particle sinking velocity measurements in the 3–400 μm size range and considerations on the effect of temperature on sinking rates

    Bach, Lennart T. / Riebesell, Ulf / Sett, Scarlett / Febiri, Sarah / Rzepka, Paul / Schulz, Kai G.

    Abstract: The flux of organic particles below the mixed layer is one major pathway of carbon from the surface into the deep ocean. The magnitude of this export flux depends on two major processes—remineralization rates and sinking velocities. Here, we present an ... ...

    Abstract The flux of organic particles below the mixed layer is one major pathway of carbon from the surface into the deep ocean. The magnitude of this export flux depends on two major processes—remineralization rates and sinking velocities. Here, we present an efficient method to measure sinking velocities of particles in the size range from approximately 3–400 μm by means of video microscopy (FlowCAM®). The method allows rapid measurement and automated analysis of mixed samples and was tested with polystyrene beads, different phytoplankton species, and sediment trap material. Sinking velocities of polystyrene beads were close to theoretical values calculated from Stokes’ Law. Sinking velocities of the investigated phytoplankton species were in reasonable agreement with published literature values and sinking velocities of material collected in sediment trap increased with particle size. Temperature had a strong effect on sinking velocities due to its influence on seawater viscosity and density. An increase in 9 °C led to a measured increase in sinking velocities of ~40 %. According to this temperature effect, an average temperature increase in 2 °C as projected for the sea surface by the end of this century could increase sinking velocities by about 6 % which might have feedbacks on carbon export into the deep ocean.
    Document type Article
    Database AGRIS - International Information System for the Agricultural Sciences and Technology

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