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  • 1
    Electronic Resource
    Electronic Resource
    Tauchbeobachtungen an Plankton und an Echostreuschichten (1967)
    Springer
    Helgoland marine research 15 (1967), S. 534-547 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Das Tauchen als Methode zur Untersuchung von Plankton und Echostreuschichten wird durch vier Beispiele erläutert: (a) Visuelle Beobachtungen an Wasserschichtungen und Grenzschichten durch Schwimmtaucher. (b) Untersuchung von Echostreuschichten durch Freitaucher, wobei sich ergab, daß angesammeltes biogenes Material in den untersuchten Sprung- beziehungsweise Streuschichten die Schallreflektion nicht beeinflußt. (c) Beobachtung von Großplankton und Feststellung von Planktonund Sestonkonzentrationen beim Tauchen mit dem Bathyscaph. (d) Untersuchung der Tiefenstreuschicht (deep scattering layer) durch Beobachtung der Vertikalwanderung bestimmter Arten des Großplanktons mit den Tauchbooten Bathyscaph und Soucoupe Plongeante. Physonectide Siphonophoren und Myctophiden standen in deutlicher Beziehung zur Tiefenstreuschicht und wurden als Echogeber erkannt. 2. Die Möglichkeiten, von Tauchbooten aus quantitative und qualitative Proben von Plankton und auch vom Benthos zu nehmen, sind zur Zeit noch unzureichend. Die Entwicklung entsprechender Geräte für den wahlweisen und mehrfachen Einsatz bei demselben Tauchgang wird empfohlen.
    Notes: Abstract Diving techniques are employed as a research tool in plankton investigations carried out in shallow water of the western Baltic Sea. Observations and samplings were made by skin divers on scattering layers corresponding to the discontinuity layers. Biogene materials, sometimes concentrated at the thermocline, are not responsible for this special kind of scattering, but rather discontinuity of salinity and temperature (Lenz 1965). For observations in deep water the use of undersea vehicles is recommended. From the Bathyscaph and the diving saucer, single plankton organisms and plankton concentrations were observed (e. g.Bernard 1958); investigations on the deep scattering layer have shown physonectid siphonophores and myctophids to be scatterers (Barham 1966). The equipment for sampling plankton and benthos from undersea vehicles is poorly developed. We need urgently gear for quantitative and qualitative sampling and for manifold use during single dives, i. e., multiple sampling gear and magazins for storage of samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01618649
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  • 2
    Electronic Resource
    Electronic Resource
    Estimation of Membrane Potential Δψ in Reconstituted Plasma Membrane Vesicles Using a Numerical Model of Oxonol VI Distribution (1997)
    Springer
    Journal of bioenergetics and biomembranes 29 (1997), S. 603-609 
    Details
    ISSN: 1573-6881
    Keywords: Membrane potential ; reconstituted plasma membrane vesicles ; oxonol VI fluorescence ; yeast H+-ATPase ; Schizosaccharomyces pombe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract A model of membrane potential-dependent distribution of oxonol VI to estimate the electrical potential difference Δψ across Schizosaccharomyces pombe plasma membrane vesicles (PMV) has been developed. Δψ was generated by the H+-ATPase reconstituted in the PMV. The model treatment was necessary since the usual calibration of the dye fluorescence changes by diffusion potentials (K+ + valinomycin) failed. The model allows for fitting of fluorescence changes at different vesicle and dye concentrations, yielding Δψ in ATP-energized PMV of 80 mV. The described model treatment to estimate Δψ may be applicable for other reconstituted membrane systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022439203461
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  • 3
    Electronic Resource
    Electronic Resource
    Aggregation Agents in German Cockroach Blattella germanica: Examination of Efficacy (1999)
    Springer
    Journal of chemical ecology 25 (1999), S. 1105-1119 
    Details
    ISSN: 1573-1561
    Keywords: Dictyoptera ; Blattellidae ; Blattella germanica ; German cockroach ; aggregation ; pheromone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Aggregation behavior and reduced locomotory activity in the German cockroach is known to be caused by chemical compounds in the feces. The attractive and/or arrestant efficacy of three relevant substances was tested in first instars by a two-choice aggregation test and in adults with a locomotion compensator apparatus that allows quantification of taste-directed orientation and walking speed as a function of antennal stimulation. The three substances tested were a feces crude extract; a mixture of six carboxylic acids (mix G) out of a total of 29 that were identified in the feces extract and tested as single compounds and in various combinations; and a steroid glucoside denoted as blattellastanoside A, which has been suggested as an aggregation arrestant pheromone in Blattella germanica. With both of our test methods, feces extract and mix G proved to be very attractive, whereas the effects of blattellastanoside A were, if anything, very poor. Possible reasons for discrepancies are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020885926578
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  • 4
    Electronic Resource
    Electronic Resource
    Inner surface and void system of regenerated cellulose fibers (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 229 (1995), S. 175-184 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die innere Oberfläche und das Hohlraumsystem von verschiedenartigen Celluloseregeneratfasern werden mit Röntgenkleinwinkelstreuung untersucht. Dabei wird gefunden, daß alle Fasern ein Hohlraumsystem von 0,01 bis 0,1% (Volumenanteil 10-4-10-3) aufweisen. Es zeigt sich jedoch, daß die Größe des Hohlraumsystems für die mechanischen Eigenschaften wenig Bedeutung hat. Es ist vielmehr die Gestalt der Hohlräume und ihre Orientierung, die hier wesentlich sind. Es wird gefunden, daß langgestreckte Hohlräume, vermutlich orientiert, für gute mechanische Eigenschaften verantwortlich sind. Damit können auch verbesserte textile Eigenschaften von Lyocellfasern des NMMO-Typs erklärt werden.
    Notes: Both the inner surface and the void system of different cellulose regenerate fibers are investigated with X-ray small angle scattering. Thereby it turns out that all fibers have a void system of 0.01 to 0.1% (volume fraction 10-4-10-3). However, the amount of the void system has little influence on the mechanical properties. Rather, it is the shape of the voids and their orientation which proves essential. It is found that elongated voids, probably well oriented, are responsible for superior mechanical properties. This explains also improved textile properties of lyocell fibers of the NMMO type.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052290112
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  • 5
    Electronic Resource
    Electronic Resource
    Bond strength of metal-ceramic systems in three-point flexure bond test (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 6 (1995), S. 55-64 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study deals with a three-point flexure test for the metal-ceramic bond involving geometrically simple specimens (alloy strips partly coated with ceramic) that can be fabricated with reasonable expenditure and sufficient reproducibility. The calculation of the stress distribution in such specimens with the aid of the finite-element method (FEM) is presented. The aim of this numerical analysis is: to investigate the stress distribution in a ceramometallic specimen with dimensions that, in a large number of experiments, have proven to lead to debonding at one end of the ceramic veneer instead of a crack in the middle of the veneer; and to assign a bond strength to the measured critical bending force that takes into account the influence of the Young's modulus of the alloy as well as a possible deviation of the thickness of the metal substrate from the standard value. Bond strength values of a variety of metal-ceramic combinations are demonstrated. These experimental results demonstrate the reproducibility of the test method as well as its sensitivity to diverse parameters. The presented method is proposed as an alternative to another flexure bond test nominated for international standard. In this test ceramometallic strips are bent over a rod to a 90° angle of the specimen ends, subsequently flattened, and the fracture surface visually inspected for adherence of the ceramic to the alloy substrate along the predominant part of the middle third of the specimen. It is clear that such a test can at most deliver qualitative results. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770060108
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  • 6
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    Microbial loop, microbial food web and classical food chain: Their significance in pelagic marine ecosystems (1992)
    Schweizerbart
    In:  Ergebnisse der Limnologie = Advances in limnology / Internationale Vereinigung für Theoretische und Angewandte Limnologie, 37 . pp. 265-278.
    Details
    Publication Date: 2018-03-19
    Description: The dependency of metabolic rates on cell size and the effect of temperature are demonstrated on a hypothetical size spectrum for a phytoplankton population in an oligotrophic open ocean region under steady-state conditions. The model spectrum illustrates the preponderance of small cells over large ones, especially their much higher weight-specific growth rates. It also shows that the allometric advantage of small cells, for instance in competing for limiting nutrients, is further enhanced by temperature increase. These basic facts are used to characterize the microbial and classical food web in relation to cold- and warm-water ecosystems and to new and regenerated production. It appears that the microbial food web is controlled by grazing and the classical food chain by nutrients. The former is present in all environments but is best adapted to oligotrophic warmwater ecosystems where regenerated production predominates. The microbial food web may be regarded as the original and normal form of life in the pelagic zone and the classical food web more as an exceptional feature depending on new production, which in turn is governed by the changing wind and temperature regime over the world ocean.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    Zooplankton standing stock and community size structure within the epipelagic zone: a comparison between the central Red Sea and the Gulf of Aden (1994)
    Springer
    In:  Marine Biology, 119 (2). pp. 191-198.
    Details
    Publication Date: 2019-09-23
    Description: Standing stock and size composition of the zooplankton comunity (〉100 μm) were studied in four depth strata of the upper 200 m of the water column during a “Meteor” cruise to the central Red Sea and Gulf of Aden in spring 1987. The central Red Sea was divided into a northern area of higher salinity and a less saline southern part. Both areas exhibited significant differences in zooplankton abundance and standing stock. The latter increased by the ratio 1:2:3 from the northern central Red Sea to its southern part and further south to the Gulf of Aden. For size structure analysis samples were fractionated into three size classes (100 to 300, 300 to 500, 500 to 5000 μm). In the central Red Sea the smallest size was dominant whereas in the Gulf of Aden the largest size fraction played a greater relative role than in the central Red Sea. This shift in size structure of the zooplankton community from the Red Sea to the Gulf of Aden is apparently primarily related to ecosystem difference between both areas, leading to a change in species composition. In addition, size reduction of individual species common to both seas may be of some significance in the extreme environment of the Red Sea.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/BF00349556
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    The life cycle of Phaeocystis (Prymnesiophycaea): evidence and hypotheses (1994)
    Elsevier
    In:  Journal of Marine Systems, 5 (1). pp. 23-39.
    Details
    Publication Date: 2019-09-23
    Description: The present paper reviews the literature related to the life cycle of the prymnesiophyte Phaeocystis and its controlling factors and proposes novel hypotheses based on unpublished observations in culture and in the field. We chiefly refer to P. globosa Scherffel as most of the observations concern this species. P. globosa exhibits a complex alternation between several types of free-living cells (non-motile, flagellates, microzoopores and possibly macrozoospores) and colonies for which neither forms nor pathways have been completely identified and described. The different types of Phaeocystis cells were reappraised on the basis of existing microscopic descriptions complemented by unpublished flow cytometric investigations. This analysis revealed the existence of at least three different types of free-living cells identified on the basis of a combination of size, motility and ploidy characteristics: non-motile cells, flagellates and microzoospores. Their respective function within Phaeocystis life cycle, and in particular their involvement in colony formation is not completely understood. Observational evidence shows that Phaeocystis colonies are initiated at the early stage of their bloom each by one free-living cell. The mechanisms controlling this cellular transformation are still uncertain due to the lack of information on the overwintering Phaeocystis fomms and on the cell type responsible for colony induction. The existence of haploid microzoospores released from senescent colonies gives however some support to sexuality involvement at some stages of colony formation. Once colonies are formed, at least two mechanisms were identified as responsible of the spreading of colony form: colony multiplication by colonial division or budding and induction of new colony from colonial cells released in the external medium after colony disruption. The latter mechanism was clearly identified, involving at least two successive cell differentiations in the following sequence: motility development, subsequent flagella loss and settlement to a surface, mucus secretion and colony formation, colonial cell division and colony growth. Aggregate formation, cell motility development and subsequent emigration from the colonies, release of non-motile cells after colony lysis on the other hand, were identified as characteristics for termination of Phaeocystis colony development. These pathways were shown to occur similarly in natural environments. In the early stages of the bloom however, many recently-formed colonies were found on the setae of Chaetoceros spp, suggesting this diatom could play a key-rôle in Phaeocystis bloom inception. Analysis of the possible environmental factors regulating the transition between the different phases of the life cycle, suggested that nutrient status and requirement of a substrate for attachment of free-living cells would be essential for initiation of the colonial form. Physical constraints obviously would be important in determining colony shape and fragmentation although autogenic factors cannot be excluded. Some evidence exists that nutrients regulate colony division, while temperature and nutrient stress would stimulate cell emigration from the colonies.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/0924-7963(94)90014-0
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
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    Mesozooplankton standing stock during the North Atlantic spring bloom study in 1989 and its potential grazing pressure on phytoplankton: a comparison between low, medium and high latitudes (1993)
    Elsevier
    In:  Deep Sea Research Part II: Topical Studies in Oceanography, 40 (1-2). pp. 559-572.
    Details
    Publication Date: 2018-03-05
    Description: Within the framework of the JGOFS Pilot Study in 1989 mesozooplankton (0.2–20 mm) was sampled by means of a Hydro-Bios multinet in five depth strata (0–25, 25–50, 50–100, 100–200, 200–500 m) during four Lagrangian drift experiments of 8–14 days' duration at 18, 33, 46 and 58°N, to follow the seasonal progress of the phytoplankton spring bloom development in the northeast Atlantic. Mesozooplankton standing stock, measured as dry weight and ash-free dry weight, increased by a factor of about 6 from 18 to 58°N. Day/night differences amounted to 10–20% of the average and were—with one exception at 18°N—not statistically significant. Using the data on weight-specific respiration rates measured by colleagues on the same cruise, the ingestion rates and potential community grazing of mesozooplankton on phytoplankton within the upper 100 m of the water column were calculated. During all four drift experiments, quasi-steady-state conditions were observed in phyto- and zooplankton standing stock, primary production and daily sedimentation at 100 m depth. The maximum potential grazing rate by mesozooplankton accounted for about half of the daily primary production. Since sedimentation of fresh phytoplankton was negligible, it is concluded that the grazing pressure exercised by mesozooplankton together with micro- and nanozooplankton was responsible for keeping the phytoplankton standing stock at a more or less constant level during the investigated spring bloom in the four areas. Particle flux was thus dominated by zooplankton faecal material.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/0967-0645(93)90032-I
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  • 10
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    Die Nordostwasser - Polynya: eine Oase in der Eiswüste? (1993)
    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 8 . pp. 12-13.
    Details
    Publication Date: 2017-09-12
    Description: Den Begriff 'Polynya' sucht man meist auch in anspruchsvollen Nachschlagewerken vergeblich. Er stammt aus dem Russischen und bezeichnet eine größere, sich über einen Zeitraum von Wochen bis Monaten erhaltende eisfreie Wasserfläche inmitten der zugefrorenen oder mit dichtem Treibeis bedeckten Meeresgebiete der Arktis und Antarktis. Ihre Größenausdehnung kann sich über hunderte und tausende von Quadratkilometern erstrecken. (...)
    Type: Article , NonPeerReviewed
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    OceanRep: Article in a Scientific Journal - without review
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