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  • 1
    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
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  • 2
    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
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 24 (1974), S. 163-166 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Für Planktonuntersuchungen in situ wurden einfache Tanks (ca. 4 m3, 5 m Tiefe) konstruiert, mit denen im Vorhafen von Helgoland während der Sommermonate 1972 und 1973 Versuche bis zu 28 Tagen durchgeführt wurden. 2. Lichtdurchlässige Kombinationsfolien aus Polyamid und Polyäthylen erwiesen sich für die an diesem Standort vorkommenden mechanischen Belastungen als geeignet. 3. Für eine kontinuierliche Durchmischung des Tankinhalts wurde ein Rührwerk entwickelt. Alle mit dem Tankinhalt in Berührung kommenden Teile waren aus physiologisch unbedenklichem Kunststoffmaterial gefertigt. 4. Die Tanks eignen sich für Simultanversuche, wie in Versuchen mit Monokulturen gezeigt werden konnte.
    Notes: Abstract For studies of in situ interactions between plankton and ambient water, simple, cylindrical, 5 m deep translucent-foil tanks were constructed using polyamide and polyethylene (layers 30 and 100 μm, respectively, with polyamide layer outside). The tanks were suspended in the water by metal frames fixed to a buoy. The whole construction was anchored in an outer basin of the harbour of Helgoland, N. Sea, and was exposed to tides and waves generated by winds of up to 6 Bft (Beaufort scale). Even under these conditions the construction and its material allowed experiments lasting 2 weeks and longer, during the summer months of 1972 and 1973. The banks' volume, of about 4 m3 each permits experiments with naturally occurring concentrations of nutrients and organisms and large sampling volumes for the determination of trace components. In this way, natural plankton populations in 1972, and monocultures of different diatom species in 1973 were investigated. Under these conditions, different monocultures developed almost identically.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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