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  • 1
    Keywords: Hochschulschrift
    Type of Medium: Online Resource
    Pages: Online-Ressource (51 Seiten, 9 MB) , Illustrationen, Diagramme, Karten
    Language: English
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  • 2
    Keywords: Hochschulschrift ; Karibik ; Meerwasser ; Carbonatisierung
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource (125 Seiten = 14 MB) , Illustrationen, Graphen, Karten
    Edition: 2021
    Language: English
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  • 3
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    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 424-425 . pp. 53-58.
    Publication Date: 2020-10-16
    Description: Calcareous foraminifera are well known for their CaCO3 shells. Yet, CaCO3 precipitation acidifies the calcifying fluid. Calcification without pH regulation would therefore rapidly create a negative feedback for CaCO3 precipitation. In unicellular organisms, like foraminifera, an effective mechanism to counteract this acidification could be the externalization of H+ from the site of calcification. In this study we show that a benthic symbiont-free foraminifer Ammonia sp. actively decreases pH within its extracellular microenvironment only while precipitating calcite. During chamber formation events the strongest pH decreases occurred in the vicinity of a newly forming chamber (range of gradient similar to 100 mu m) with a recorded minimum of 6.31 (〈10 mu m from the shell) and a maximum duration of 7 h. The acidification was actively regulated by the foraminifera and correlated with shell diameters, indicating that the amount of protons removed during calcification is directly related to the volume of calcite precipitated. The here presented findings imply that H+ expulsion as a result of calcification may be a wider strategy for maintaining pH homeostasis in unicellular calcifying organisms
    Type: Article , PeerReviewed
    Format: text
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  • 4
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    AGU (American Geophysical Union) | Wiley
    In:  Geochemistry, Geophysics, Geosystems, 14 (1). pp. 102-111.
    Publication Date: 2013-10-28
    Description: The chemical and isotopic composition of foraminiferal shells (so-called proxies) reflects the physico-chemical properties of the seawater. In current day paleoclimate research, the reconstruction of past seawater carbonate system to infer atmospheric CO2 concentrations is one of the most pressing challenges and a variety of proxies have been investigated, such as foraminiferal U/Ca. Since in natural seawater and traditional CO2 perturbation experiments, the carbonate system parameters co-vary, it is not possible to determine the parameter of the carbonate system causing e.g. changes in U/Ca, complicating the use of the latter as a carbonate system proxy. We overcome this problem, by culturing the benthic foraminifer Ammonia sp. at a range of carbonate chemistry manipulation treatments. Shell U/Ca values were determined to test sensitivity of U incorporation to various parameters of the carbonate system. We argue that [CO32-] is the parameter affecting the U/Ca ratio and consequently, the partitioning coefficient for U in Ammonia sp DU. We can confirm the strong potential of foraminiferal U/Ca as a [CO32-] proxy.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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  • 5
    Publication Date: 2013-10-28
    Description: About 30% of the anthropogenically released CO2 is taken up by the oceans; such uptake causes surface ocean pH to decrease and is commonly referred to as ocean acidification (OA). Foraminifera are one of the most abundant groups of marine calcifiers, estimated to precipitate ca. 50 % of biogenic calcium carbonate in the open oceans. We have compiled the state of the art literature on OA effects on foraminifera, because the majority of OA research on this group was published within the last three years. Disparate responses of this important group of marine calcifiers to OA were reported, highlighting the importance of a process-based understanding of OA effects on foraminifera. We cultured the benthic foraminifer Ammonia sp. under a range of carbonate chemistry manipulation treatments to identify the parameter of the carbonate system causing the observed effects. This parameter identification is the first step towards a process-based understanding. We argue that [CO32−] is the parameter affecting foraminiferal size-normalized weights (SNWs) and growth rates. Based on the presented data, we can confirm the strong potential of Ammonia sp. foraminiferal SNW as a [CO32−] proxy.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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  • 6
    Publication Date: 2020-02-06
    Description: The impact of anthropogenic ocean acidification (OA) on marine ecosystems is a vital concern facing marine scientists and managers of ocean resources. Euthecosomatous pteropods (holoplanktonic gastropods) represent an excellent sentinel for indicating exposure to anthropogenic OA because of the sensitivity of their aragonite shells to the OA conditions less favorable for calcification. However, an integration of observations, experiments and modelling efforts is needed to make accurate predictions of how these organisms will respond to future changes to their environment. Our understanding of the underlying organismal biology and life history is far from complete and must be improved if we are to comprehend fully the responses of these organisms to the multitude of stressors in their environment beyond OA. This review considers the present state of research and understanding of euthecosomatous pteropod biology and ecology of these organisms and considers promising new laboratory methods, advances in instrumentation (such as molecular, trace elements, stable isotopes, palaeobiology alongside autonomous sampling platforms, CT scanning and high-quality video recording) and novel field-based approaches (i.e. studies of upwelling and CO2 vent regions) that may allow us to improve our predictive capacity of their vulnerability and/or resilience. In addition to playing a critical ecological and biogeochemical role, pteropods can offer a significant value as an early-indicator of anthropogenic OA. This role as a sentinel species should be developed further to consolidate their potential use within marine environmental management policy making.
    Type: Article , PeerReviewed
    Format: text
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  • 7
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    In:  (Diploma thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 123 pp
    Publication Date: 2021-12-01
    Description: The carbonate chemistry of seawater is changing due to the uptake of increasing atmospheric C02 and is of major scientific concem. The decrease in the aragonite saturation state (Qaragonite) is of special interest, because the ability of some marine organisms (e.g. corals) to form calcium carbonate via biomineralization is suspected to be depending on aragonite saturation in the surrounding seawater. The objective of this thesis was to investigate the aragonite saturation state of two marginal seas, the Gulf of Mexico and the Caribbean Sea. Presented are the results of five cruises that were carried out in the Greater Caribbean Region (including the Gulf of Mexico) in 2008. At least two carbonaterelated analytical parameters were determined on each cruise, which made possible the calculation of the other parameters of the carbonate system, including the aragonite saturation state. All surface waters were supersaturated with respect to Ωaragonite with an average aragonite saturation state of 4.16 (± 0.3) in the Gulf of Mexico and 4.18 (± 0.09) in the Caribbean Sea.
    Type: Thesis , NonPeerReviewed
    Format: text
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  • 8
    Publication Date: 2024-02-07
    Description: Marine carbon and nitrogen processing through microorganisms’ metabolism is an important aspect of the global element cycles. For that purpose, we used foraminifera to analyze the element turnover with different algae food sources. In the Baltic Sea, benthic foraminifera are quite common and therefore it is important to understand their metabolism. Especially, Cribroelphidium selseyense, also occurring in the Baltic Sea, has often been used for laboratory feeding experiments to test their effect on carbon or nitrogen turnover. Therefore, foraminifera were collected from the Kiel Fjord and fed with six different algal species in two qualities (freeze-dried algae vs. fresh algae, all 13C- and 15N-labeled). Also, labeled dissolved inorganic C and N compounds and glucose were offered to the foraminifera to test direct assimilation of dissolved compounds (carbon and nitrogen) from the water column. Our experiments showed that after 15 days of incubation, there were highly significant differences in isotope labeling in foraminifera fed with fresh algae and dry algae, depending on algal species. Further, different algal species led to different 13C and 15N enrichment in the studied foraminifera, highlighting a feeding preference for one diatom species and an Eustigmatophyte. A significant carbon assimilation from HCO3– was observed after 7 days of incubation. The N assimilation from NH4+ was significantly higher than for NO3– as an inorganic N source. The uptake of glucose showed a lag phase, which was often observed during past experiments, where foraminifera were in a steady state and showed no food uptake at regular intervals. These results highlight the importance of food quality on the feeding behavior and metabolic pathways for further studies of foraminiferal nutrition and nutrient cycling.
    Type: Article , PeerReviewed
    Format: text
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  • 9
    Publication Date: 2023-11-25
    Keywords: BIOACID; Biological Impacts of Ocean Acidification; Calcium concentration change; Calculated; Comment; EPOCA; European Project on Ocean Acidification; Mediterranean Sea Acidification in a Changing Climate; MedSeA; pH change
    Type: Dataset
    Format: text/tab-separated-values, 293 data points
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  • 10
    Publication Date: 2023-11-25
    Keywords: Ammonia sp., size; Backlit microscope (Zeiss Axiovert 200 M); BIOACID; Biological Impacts of Ocean Acidification; Calculated; EPOCA; European Project on Ocean Acidification; Identification; Mediterranean Sea Acidification in a Changing Climate; MedSeA; pH change
    Type: Dataset
    Format: text/tab-separated-values, 134 data points
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