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  • 1980-1984  (3)
  • 1975-1979  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Parallel plastic tank experiments with cultures of marine diatoms (1977)
    Springer
    Helgoland marine research 30 (1977), S. 201-216 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The reproductibility of tank experiments concerning unicellular marine algal development was analyzed by means of parallel experiments with cultures ofThalassiosira rotula andSkeletonema costatum, using large flexible plastic tanks under semi-natural conditions. The tanks (3–4 m3, 4–5 m deep) were exposed in the German Bight at a station in the outer harbour of helgoland. The water was obtained from the open North Sea in towable tanks; it was filtered (plate filter), enriched with nitrate (20–30 μgat dm−3), phosphate (1.3–2.3 μgat dm−3) and silicate (15–23 μgat dm−3)-nearly natural springtime concentrations in this area-and inoculated with 103–105 cells dm−3. The water was mixed with non-metal stirring equipment. Within 5 days, concentrations of 106–107 cells dm−3 in an exponential growth phase were obtained. In experiments withT. rotula a parallel development was achieved in spite of some contamination by surrounding water. This is the case for nearly all parameters analyzed (nutrient salts, phytoplankton, bacteria, C, N and particulate carbohydrates). The heterotrophic bacteria, which were determined by means of the plate method, reached concentrations of up to 106 (T. rotula) and 105 (S. costatum) CFU cm−3, respectively. They showed a consistent retrograde development at diatom concentrations above a certain level. The crop did not increase again until the diatoms had reached the stationary phase. During exponential growth ofT. rotula (G=8.9–11.7 h) a partially synchronous cell division was observed. There were also rhythms with respect to cell size (pervalvar axes) and chain length (number of cells). For the experiments withS. costatum (G=10–11.4 h) diurnal variations of cell size and chain length occurred. The present results indicate acceptable reproducibility of algal development and related phenomena in enclosed water bodies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02207836
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Natürliche Oberflächenfilme im Seegebiet vor Sylt (1976)
    Springer
    Marine biology 36 (1976), S. 135-146 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The physical and chemical properties of the sea surface can be altered considerably by the formation of slicks and the accumulation of particles (including plankton). Investigations of natural slicks near the island of Sylt consisted of analyses of the dissolved and particulate surface-active substances, as well as the identification of plankton and bacteria collected by a surface-film sampler. The analyzed surface material consisted primarily of phytoplankton (Prorocentrum micans in particular), bacteria, detritus and dissolved compounds of fatty acids. These fatty acid compounds alone would not account for the slick. The slick appeared to be caused by the calm weather, the active accumulation of P. micans at the surface, and the increase in bacteria associated with this accumulation. Here a decrease was observed in the dissolved surface-active substances compared with the concentration usually found in normal surface waters, of which the total fatty acid content in a sample was taken as indicator. In some cases a correlation was found between fatty acids and particulate matter in naturally occurring slicks. Particularly large variations were found in the fatty acid patterns in the filtrate and filter residue at a time when no slick was present and no particulate matter had accumulated at the surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388436
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The development of a natural plankton population in an outdoor tank with nutrient-poor sea water. I. Phytoplankton succession (1977)
    Springer
    Marine biology 43 (1977), S. 1-17 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Due to complex hydrodynamic and biological inhomogeneities, the phytoplankton species succession cannot be satisfactorily observed, apart from the seasonal blooms which occur in temperate waters. Large flexible plastic tanks have proved to be useful for such observations. In 1972, for 28 days, a phytoplankton succession in nutrient-poor water in the outer harbor of Helgoland was observed in a flexible plastic tank (3 m3). During this period, 3 phytoplankton biomass maxima were formed with many significant correlations. In the first 7 days the ammonia concentration decreased from over 6 to 2 μ mol 1-1 for 14 days. The nitrate concentration remained in the range of 3–6 μ mol 1-1 and then fell abruptly to 0–2 μ mol 1-1. The phosphate concentration was about 0.1 μ mol 1-1. Lauderia borealis dominated the first period, and its increase was significantly correlated with the decrease in ammonia. The diatom was succeeded by two dinoflagellates, Dinophysis acuminata and Prorocentrum micans. The last period of the experiment was characterized by a stronger development of Rhizosolenia species. The rapid recovery of the crop in the nutrient-poor water points to intensive remineralization processes. The irregular occurrence of ammonia near the surface was correlated with the appearance of Noctiluca miliaris at this depth. It is expected that repetitions of this type of experiment will permit further explanations of statistical correlations which are not yet clear. As a first step, in order to test hypotheses, a correlation analysis was employed to eliminate the statistically non-significant correlations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392567
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Rhythmic release of dissolved free amino acids from partly synchronized Thalassiosira rotula under nearly natural conditions (1983)
    Springer
    Marine biology 74 (1983), S. 305-312 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In outdoor tanks enclosed monocultures of Thalassiosira rotula showed partly synchronized cell divisions during exponential growth. The changes in division activity showed a characteristic frequency, which also could be found for cell length (pervalvar axis) and assimilation rate as well as for concentration changes of dissolved free amino acids (DFAA) and ammonia. Excretion of DFAA occurred preferentially during periods of reduced cell division activity, when assimilation was at a higher level. The concentration of ammonia decreased during these periods. The rates per hour of these parameters showed significant multiple correlations. The release of six individual amino acids (ala, β-ala, gly, lys, orn and ser) seemed to be controlled by the physiological status of the diatoms. These amino acids amounted to a portion of about 70–80% of the total DFAA. Uptake and release rates of DFAA nitrogen and ammonia were in the same range with maxima of about 350 ng at nitrogen dm-3 h-1 and litre. These dynamics pointed to strong fluxes of organic bound nitrogen in marine micro-heterotrophs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403456
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Semi-automated methods for the determination of particulate phosphorus in the marine environment (1980)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 301 (1980), S. 14-16 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Phosphor in Wasser ; Spektralphotometrie, AutoAnalyzer, Meerwasser, partikulärer Phosphor, Mo-Komplex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary After filtration of sea water through glass fiber filters, the filters with the residue are digested by heating with sulphuric acid and hydrogen peroxide. The following determination of phosphate is based on the formation of a phosphomolybdenum complex. It has been modified in such a way that the phosphorus content of the samples can be determined with a continuous-flow system with the TechniconAutoAnalyzer direct after digestion. Two methods are described for different sensitivities of 0.1–10μmol P · l−1.
    Notes: Zusammenfassung Der Rückstand bei Filtration von Meerwasser durch Glasfaserfilter wird mit Schwefelsäure und Wasserstoffperoxid aufgeschlossen. Die anschließende Phosphatbestimmung basiert auf der Bildung eines Phosphormolybdän-Komplexes. Sie wurde modifiziert, so daß der Phosphor-Gehalt der Proben sofort nach Aufschluß mit dem Durchflußsystem des Technicon-AutoAnalyzers bestimmt werden kann. Zwei Methoden mit unterschiedlicher Empfindlichkeit (von 0,1–10μmol P · l−1) werden beschrieben.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00481264
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    Paper (German National Licenses)
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  • 6
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    Unknown
    Release of dissolved free amino acids during a bloom of Thalassiosira rotula (1981)
    Institut für Meereskunde
    Details
    Publication Date: 2022-05-24
    Description: Three large plastic enclosures (3-4 m3) were anchored in the outer harbour of Helgoland (German Bight) and filled with natural seawater which was filtered free of algae. The enclosed water bodies were enriched with inorganic nutrients and inoculated with the diatom Thalassiosira rotula. During the growth of the algae diurnal changes in concentration of dissolved free amino acids (DFAA) occurred. The periodic concentration changes of individual amino acids with a low carbon to nitrogen ratio showed significant interrelationships with the partly synchronous devisions of the diatoms. From the exponential to the stationary phase the carbon to nitrogen ratio of DFAA shifted to higher values pointing at an adaptation of the organisms to the decreasing inorganic nitrogen source. During the bloom amino acids relatively rich in nitrogen were mainly excreted but by the end of the growth amino acids with a higher carbon content predominated. At phases of high photosynthetic activity the organisms probably reduced the high osmotic pressure by exudation of DFAA.
    Type: Article , NonPeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - without review
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