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  • 1
    Electronic Resource
    Electronic Resource
    Cycling of organic nitrogen in marine plankton communities studied in enclosed water columns (1980)
    Springer
    Marine biology 59 (1980), S. 15-21 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Concentrations of fluorescamine-positive substances (primary amines) and turnover rates of L-leucine pools were measured concurrently in seawater samples taken from 1300 m3 plastic enclosures moored in Saanich Inlet, British Columbia, Canada. Concentration and turnover rates of dissolved free amino acids were calculated and then used to determine the instantaneous flux of dissolved free amino acids, which ranged from 0.09 to 2.42 μM d-1 (i.e.,5 to 145 μgC l-1 d-1). This flux was highest in the euphotic zone, and was related to net primary production but not to the type of dominant primary producer. Comparison of the flux to changes in the concentration of ammonia in deep water suggested that amino acid degradation accounted for 60% of the flux into the ammonia pool. For a given sample, the amino acid carbon flux ranged from 17 to 210% (mean=78%) of the primary production. Such fluxes of amino acid carbon, if used exclusively by the bacterioplankton, would give growth rates ranging from 0.3 to 3.0 (mean=1.7) bacterial doublings d-1. These calculations indicate that a large fraction of the community carbon and nitrogen flux passes through the bacterioplankton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396978
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Thymidine incorporation as a measure of heterotrophic bacterioplankton production in marine surface waters: Evaluation and field results (1982)
    Springer
    Marine biology 66 (1982), S. 109-120 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To assess bacterioplankton production in the sea, we have developed a procedure for measuring growth based on incorporation of tritiated thymidine into DNA; the accuracy of this procedure was tested under a variety of laboratory and field conditions. By autoradiography, we have found that for all practical purposes our technique is specific for the nonphotosynthetic bacteria and that virtually all of the “active” bacteria (one-third or more of the total countable bacteria) take up thymidine. We also measured (1) the intracellular isotope dilution of thymidine assessed by parallel experiments with labeled phosphorus, and (2) DNA content of natural marine bacteria (0.2 to 0.6 μm size fraction); a conversion factor derived from these data permitted estimation of production from thymidine incorporation results. A very similar conversion factor was independently derived from the empirical relationship between thymidine incorporation and growth of natural bacterioplankton under controlled conditions. Combined results show that this technique, which can be performed rapidly and easily at sea, provides good estimates of production. Data from Southern California Bight waters, which contain oligotrophic as well as moderately eutrophic regions, show that average bacterioplankton doubling times, like those of the phytoplankton, are on the order of a few days, with fastest growth at depths just below those of greatest phytoplankton abundance. Offshore bacterial production is roughly 5 to 25% of the primary production; thus, at a 50% assimilation efficiency, the bacterioplankton would consume 10 to 50% of the total fixed carbon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397184
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Bacterioplankton in the coastal euphotic zone: Distribution, activity and possible relationships with phytoplankton (1980)
    Springer
    Marine biology 60 (1980), S. 201-207 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacterioplankton were studied in the euphotic zone of the Southern California Bight, USA, with special attention to biological factors affecting bacterial distribution and activity. Measurements were made of bacterial abundance, thymidine incorporation into acid insoluble material, primary production (particulate and dissolved), chlorophyll, phaeopigments, total microbial ATP, particulate organic carbon and nitrogen, dissolved organic carbon, dissolved primary amines, and glucose and thymidine turnover rates. The data were analyzed by pairwise rank correlations with significance tested at the P〈.005 level. Bacterial abundance and thymidine incorporation both declined progressively with increasing distance from shore (to 100 km); similar trends occurred for the phytoplankton, with several stations having subsurface maxima. Bacterial abundance, thymidine incorporation, and thymidine and glucose turnover rates were all significantly correlated to each other, suggesting they are comparable as relative measures of bacterial activity. Thymidine incorporation per cell, an indicator of specific growth rate, was not correlated to bacterial abundance, suggesting density independent specific growth rates. Bacterioplankton growth rate was evidently influenced more by the standing stock of phytoplankton than by the primary production of the phytoplankton. Thus, bacterial growth may possibly be stimulated by leakage of dissolved organic matter not so much from healthy photosynthesizing cells as from phytoplankton being disrupted and incompletely digested during predation by the zooplankton and nekton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00389163
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Microbial uptake of dissolved organic matter in Mcmurdo Sound, Antarctica (1981)
    Springer
    Marine biology 61 (1981), S. 89-94 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distribution and activity of bacterioplankton, and the turnover of dissolved organic matter (DOM) were examined in McMurdo Sound, Antarctica. On the eastern side of the Sound, bacteria averaged 6.5×108 l-1, and turnover rates of dissolved adenosine triphosphate, D-glucose and l-leucine averaged 16, 116 and 124 h, respecitvely. These molecules as well as thymidine were taken up maximally from 0° to 5°C and near-maximally from -1.5° to 0°C, indicating bacterial adaptation to rapid turnover of dissolved organic matter at the ambient temperature. On the west side of the Sound, bacteria averaged only 0.65×108 l-1, and turnover times for adenosine triphosphate, D-glucose and lleucine averaged 59, 20454, and 3070 h, respectively. Total microbial adenosine triphosphate (an indicator of total microbial biomass) and chlorophyll a were also much lower at the western than at the eastern side stations. Moreover, no primary production could be detected at one western side station (New Harbor). Thus, in McMurdo Sound, the western side is highly oligotrophic, but the eastern side has an abundant active bacterioplankton, comparable to that of temperate coastal waters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386648
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    IgA COMMITMENT: MODELS FOR B-CELL DIFFERENTIATION AND POSSIBLE ROLES FOR T-CELLS IN REGULATING B-CELL DEVELOPMENT (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 409 (1983), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1983.tb26857.x
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Marine alga Platymonas sp. accumulates silicon without apparent requirement (1978)
    [s.l.] : Nature Publishing Group
    Nature 272 (1978), S. 244-246 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Our investigation was stimulated by the discovery that certain species of marine phytoplankton, particularly members of the Dinophyceae, Prasinophyceae, Prymnesiophyceae and Cyano-phyceae contained amounts of silicon equivalent to that found in diatoms of comparable size, while other species ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/272244a0
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Mechanoreception in calanoid copepods (1986)
    Springer
    Marine biology 90 (1986), S. 529-535 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A model of early detection of individual algal prey by copepod mechanoreception suggests that mechanoreception may serve as an indicator of prey position. Our model shows that the magnitude of the pressure disturbance created by a particle entrained in a feeding flow of a copepod increases linearly with increasing particle size, decreases as the square of the distance away from the antenna, and is unique for a given particle size. These pressure disturbances may be utilized by the copepod to determine the size and location of particles present in the feeding current and may provide information necessary for initial prey detection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409273
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    Paper (German National Licenses)
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