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  • ANT-XXXIII/2; Bacterial production; CombiBac; CTD/Rosette; CTD-RO; DEPTH, water; Ecology & Environment; Estimated; Event label; Incorporation of 14C-leucine (Simon and Azam, 1989, http://www.int-res.com/articles/meps/51/m051p201.pdf; Simon et al. 2004, doi:10.4319/lo.2004.49.4.1035); Incubation temperature; Kombinierte Effekte von Temperatur und Ressourcenverfügbarkeit auf den Abbau von organischem Material durch Antarktisches Bakterioplankton; Lazarev Sea; Microbiology; Polarstern; Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; PS111; PS111_101-1; PS111_10-2; PS111_12-2; PS111_123-1; PS111_131-1; PS111_132-1; PS111_137-2; PS111_140-1; PS111_14-1; PS111_16-1; PS111_17-1; PS111_22-1; PS111_28-1; PS111_33-1; PS111_37-2; PS111_40-3; PS111_47-1; PS111_51-1; PS111_58-1; PS111_62-1; PS111_68-1; PS111_74-1; PS111_82-1; PS111_89-1; PS111_9-3; Sample ID; South Atlantic Ocean; SPP1158; Weddell Sea  (1)
  • Hochschulschrift  (1)
  • Oxygen  (1)
Document type
Keywords
Publisher
Language
Years
  • 1
    Keywords: Hochschulschrift ; Phytoplankton ; Klimaänderung
    Description / Table of Contents: Global warming has already and is continuing to impact the global oceans. Half of the global primary production is performed by phytoplankton in the oceans and heterotrophic marine bacteria channel a substantial amount of primary organic carbon through the microbial loop. Understanding the influence of climate change on these important processes is therefore essential for an assessment of the vulnerability of the carbon cycle and possible feedbacks. This thesis reports results from investigations on the temperature dependent coupling between phytoplankton and bacterioplankton, with respect to additional effects of light intensity and inorganic nutrient concentrations. During four consecutive years, mesocosm experiments with natural Kiel Fjord winter plankton communities investigated the influences of increasing water temperatures of up to ?T +6ʿC and different light intensities between 16 and 100% of natural incident light. In an additional microcosm experiment with a single algal species and the natural bacterial community, two inorganic nutrient concentrations were used, in order to evaluate the combined effects of temperature and substrate on the algal-bacterial coupling. Summarising the results from all experiments it can be concluded, that increasing temperatures generally led to an increased heterotrophic bacterial organic substrate utilisation relative to primary production. In combination with a further brightening, the supplemental promotion of primary production would increase the absolute amounts of cycled organic matter. Future increasing P-limitation in coastal waters would lead not only to an enhanced absolute amount of cycled carbon, but additionally to an increased relative amount of remineralised organic carbon through the microbial loop. An enhanced organic matter transfer through the microbial loop has the potential to alter the whole structure and functioning of the marine food web and the biological sequestration of carbon to depth. Additionally, a substantial rise of CO2 emissions through enhanced respiration represents a positive feedback loop to the global climate change problem.
    Type of Medium: Online Resource
    Pages: Online-Ressource (pdf-Datei: 199 S., 1,7 MB)
    DDC: 578.77622
    Language: English
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  • 2
    ISSN: 1432-2013
    Keywords: Diffusion coefficient ; Muscle cells ; Myoglobin ; Microinjection ; Oxygen ; Facilitated diffusion ; Intracellular oxygen transport ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We measured the diffusion coefficient of myoglobin (D Mb) inside mammalian skeletal muscle cells with a microinjection technique. A small bolus of horse Mb was injected into a single muscle fibre and the subsequent time-dependent changes of the Mb profiles along the fibre axis were measured with a microscope-photometer. For fibres of the rat soleus muscle at 22° C, a D Mb of 1.3·10−7 cm2/s was found, confirming a result obtained previously by us for rat diaphragm muscle with a photo-oxidation technique. In the extensor digitorum longus muscle of the rat, a higher value of 1.9 · 10−7 cm2/s was measured. Auxotonic muscle contractions did not change the apparent D Mb. For the temperature range between 22 ° C and 37 ° C, a temperature coefficient, Q 10, of 1.5 was calculated. The implication of this result for the role of Mb in the facilitation of oxygen transport was examined. Model calculations show that with this relatively low D Mb value, the intracellular oxygen supply can be improved only slightly.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2023-10-28
    Description: Global warming poses new threats to marine ecosystems since rising seawater temperature potentially induces cascading effects in biogeochemical cycles and food webs. Heterotrophic bacteria are the main producers of CO2 in the ocean, thereby counteracting the biological drawdown of CO2 by primary production. In Antarctic marine systems, low seawater temperature, and the low availability of labile organic matter are major environmental constraints on bacterial growth and degradation activity. However, temperature and the availability of resources for heterotrophic bacteria undergo considerable change induced by climate warming combined with subsequent ice melt and changes in primary productivity. This project aims to test single and combined effects of temperature and organic matter availability on Antarctic marine bacterioplankton. This data set includes measurements on bacterial biomass production at 0°C and 3°C measured alongside the CTD casts during the Polarstern cruise PS111 to the Weddell Sea. Samples were collected in the upper 100 m of the water column at the Eastern Weddell Sea Shelf and at the Filchner-Ronne ice shelf.
    Keywords: ANT-XXXIII/2; Bacterial production; CombiBac; CTD/Rosette; CTD-RO; DEPTH, water; Ecology & Environment; Estimated; Event label; Incorporation of 14C-leucine (Simon and Azam, 1989, http://www.int-res.com/articles/meps/51/m051p201.pdf; Simon et al. 2004, doi:10.4319/lo.2004.49.4.1035); Incubation temperature; Kombinierte Effekte von Temperatur und Ressourcenverfügbarkeit auf den Abbau von organischem Material durch Antarktisches Bakterioplankton; Lazarev Sea; Microbiology; Polarstern; Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; PS111; PS111_101-1; PS111_10-2; PS111_12-2; PS111_123-1; PS111_131-1; PS111_132-1; PS111_137-2; PS111_140-1; PS111_14-1; PS111_16-1; PS111_17-1; PS111_22-1; PS111_28-1; PS111_33-1; PS111_37-2; PS111_40-3; PS111_47-1; PS111_51-1; PS111_58-1; PS111_62-1; PS111_68-1; PS111_74-1; PS111_82-1; PS111_89-1; PS111_9-3; Sample ID; South Atlantic Ocean; SPP1158; Weddell Sea
    Type: Dataset
    Format: text/tab-separated-values, 2548 data points
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