Number 02

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  • Publication
    2021-10-01Heft oder Ausgabe einer Zeitschrift
    Proceedings in Marine Biology
    (Lebenswissenschaftliche Fakultät) Burchardi, Anja; Busse, Wayne; Enge, Alexander; Griesbaum, Frederic; Le, Mai-Lee Van; Merten, Luisa; Nickel, Marie; Ohlrogge, Carina; Purkart, Leopold
    Zeitschrift zur Kursreise der Freien Universität Berlin (Deutschland) an die Kristinebergs Marina Forskningsstation (Schweden)
  • Publication
    2021-10-01Zeitschriftenartikel
    Sedimentspezifität des Bäuchenröhrenwurms Lanice conchilega
    (Lebenswissenschaftliche Fakultät) Markus, Lara; Pilic, Antonia
    The common tube-building polychaete Lanice conchilega is known as a habitat structuring species and widespread in intertidal and subtidal regions down to 1900 m water depth. By effecting hydrodynamics, increasing the habitat stability, and oxygen supply, L. conchilega accomplishes to change a formerly uniform environment into a heterogeneous habitat (Van Hoey et al., 2008). Nevertheless, L. conchilega abundance is affected by physical factors like sedimentology, flow regime, as well as the availability of food (Willems et al., 2008). This study focuses on the physical factor sediment composition. Hence, sand was collected in L. conchilega forming zones, examined in the laboratory with sieves of different mesh sizes for analysis of the grain size distribution in relation to L. conchilega abundance. Moreover, the depth of the oxidation layer in the respective sediment and duration of water submergence were determined. Here, we report a significant correlation between the abundance of tubes of L. conchilega and the relative quantity of rough sediment. Furthermore, we found that the number of tubes of L. conchilega is negatively correlated to the thickness of the oxidation layer.
  • Publication
    2021-10-01Zeitschriftenartikel
    Watt krabbelt denn da? Ein Vergleich der drei küstenbewohnenden Krabbenarten Carcinus maenas, Hemigrapsus takanoi und Hemigrapsus sanguineus auf Sylt
    (Lebenswissenschaftliche Fakultät) Enge, Alexander; Griesbaum, Frederic
    The green crab Carcinus maenas is a common littoral crab and belongs to the most invasive species on earth. Due to human transport systems across the oceans, this species had the opportunity to spread worldwide. But for several years new species from Asia invade the former home waters of Carcinus maenas and are threa- tening its own territory: Hemigrapsus spp. It is not clear yet how the impact of the alien crab influences the green crab, but worries exist because the number of Carcinus maenas has locally decreased while numbers of Hemigrapsus spp. increased enormously at the same time. Furthermore, the distribution of the species, respectively, varies strongly: Hemigrapsus takanoi seems to prefer oyster benches whereas Hemigrapsus sanguineus inhabits rocky groynes, only 650m separated from each other. In the experiments, no obvious competition between the crabs was seen, but Hemigrapsus takanoi tended to appear more aggressive.
  • Publication
    2021-10-01Zeitschriftenartikel
    Der Einfluss von Seepockenbefall auf die Agilität von Littorina littorea
    (Lebenswissenschaftliche Fakultät) Merten, Luisa; Le, Mai-Lee Van
    In the Wadden sea of Sylt Littorina littorea constitutes a wide spreaded species of snails. Since L. littorea possesses no defence mechanisms against settling by epibionts such as chemical barricades, the periwinkles are often strongly overgrown by barnacles and larval states of mussels and oysters. The most common epibiont on L. littorea is the barnacle Balanus crenatus. In this study we examine the effects of barnacle overgrowth on the agility of L. littorea. In order to analyse the influence of heavy overgrowth, individuals were sampled, weighed and categorized. Three experimental groups, two with contrasting severity of overgrowth and one with removed barnacles, were tested. Experiments revealed that heavy barnacle overgrowth affected the mobility of the periwinkles substantially. Moreover snails with removed barnacles performed as successful or occasionally more successful than snails without barnacles. This might demonstrate a certain training effect of snails with removed barnacles due to their adaptation to a heavier weight load.
  • Publication
    2021-10-01Zeitschriftenartikel
    Der Einsiedlerkrebs - Ein Tier mit Persönlich- keit? Auswirkungen von Stressfaktoren bei Pa- gurus bernhardus (Crustacea: Decapoda)
    (Lebenswissenschaftliche Fakultät) Burchardi, Anja; Nickel, Marie; Ohlrogge, Carina
    Personality in animals has been studied on many different species and is based on the observation and inve- stigation of behavioural traits. The common hermit crab, Pagurus bernhardus, indigenous to the mud flats in the North Sea, is known to feel pain and to directly react to negative experiences. To investigate if such reaction is specific regarding individuals, or if this reaction occurs randomly, two different environmental stressors have been simulated on 78 hermit crabs. After each stressor, time was measured until the hermit crab emerged its forelimbs out of the shell. 32 hermit crabs did not show similar responses in both trials, while 46 hermit crabs responded similar. Thus, the study provides evidence that hermit crabs do not respond due to a certain personality but react randomly to different stressors.
  • Publication
    2021-10-01Zeitschriftenartikel
    Quantitative Analyse der Polychaetengemein- schaft des Watts am Lister Haken auf Sylt
    (Lebenswissenschaftliche Fakultät) Purkart, Leopold; Busse, Wayne
    In order to test if there is a connection between sediment structure and the abundance of certain Polychaeta, samples of three different spots in the intertidal zone of the wadden sea on Sylt were analysed with respect to species composition and population density of bristleworms. We examined two different kinds of sediment, muddy sands and mudflats. There was a clear dominance of Nereis virens and a lack of other species in the muddy sands, whereas the mudflats showed a high diversity of different Polychaeta such as Heteromastus filiformis, Tharyx killariensis or Scoloplos armiger. The muddy sands, however, receive influx of organic material from a pipe and are partially isolated from the rest of the wadden sea, which might have an impact on Polychaeta diversity. Analysis of sediment properties showed only few differences in grain size between the two spots. Finally, our findings consider anthropogenic pollution and the isolated position of the muddy sands near Lister Haken on Sylt to cause a clear decrease in local biodiversity in comparison to the adjacent mudflats.