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  • 1
    Electronic Resource
    Electronic Resource
    Icy heritage: ecological evolution of the postglacial Baltic Sea reflected in the allozymes of a living fossil, the priapulid Halicryptus spinulosus (1996)
    Springer
    Marine biology 125 (1996), S. 671-685 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genetic variation of 16 allozyme loci in 397 Halicryptus spinulosus (Priapulida) revealed overall polymorphism of P=0.438 and Hardy-Weinberg expectations for heterozygosity of H e=0.060 for Baltic Sea stocks, H e=0.143 for the White Sea and H e=0.121 for Iceland. Maximal unbiased standard distances of D=0.0693 separated Baltic and White Sea populations. Nordic and Baltic populations could be distinguished by allozymes, but Baltic subsamples proved cohesive. Gene flow amounted to effective exchange values per generation of N m=2.94 over 650 km of continuous habitat, N m=10.65 over 175 km, and N m=13.85 over 20 km. Gene flow started to decrease with geographic distance beyond a dispersal threshold of 20 km, but hierarchical G ST-statistics indicated light isolation by distance beyond a minimum of 8 km. Gene flow is high for a benthic worm assumed to lack dispersal by pelagic larva, a paradox which cannot be resolved now. Baltic populations are characterized by lower heterozygosity than Nordic stocks. In the Baltic Basin, temporally continuous brackish-water conditions have only existed for the past 7000 years. The two possible colonization routes of H. spinulosus to the geologically young Baltic Sea imply genetic drift, whether by founder effect (sweepstake colonization from Iceland) or by refugial bottlenecking during the Ancylus phase of the Baltic Basin after a direct connection to the White Sea had been sequestered. Continued genetic drift is emphasized by lower heterozygosity in the ecologically unstable Belt Sea compared to the central Baltic. Allozymes falsify the reduced-mutability hypothesis to explain bradytelic evolution of Priapulida. Regional genetic homogeneity, ample polymorphism, and preference for anoxic black mud qualify H. spinulosus populations as indicators of microevolutionary responses to water circulation regimes or pollution in the Baltic Sea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349249
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Endogenous circatidal rhythm in the Manila clam Ruditapes philippinarum (Bivalvia: Veneridae) (1999)
    Springer
    Marine biology 134 (1999), S. 107-112 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Manila clams, Ruditapes philippinarum, removed from their natural environment and maintained for 9 weeks in continuously immersed conditions exhibited a clear endogenous circatidal rhythm in oxygen consumption. The clams exhibited a semidiurnal rhythmicity in oxygen consumption after showing a diurnal pattern in the first few days (5 to 7 d) of the experiment. The results of the present study indicate that activity rhythms of clams are controlled not only by exogenous factors, but also by an endogenous circatidal periodicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050529
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Meiofaunaentwicklung auf künstlichen Weichböden in der Kieler Bucht (1979)
    Springer
    Helgoland marine research 32 (1979), S. 305-312 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The “Benthosgarten”, an enclosed area in the western Baltic Sea, is used for benthos ecology experiments. It consists of different kinds of sediment containers filled with “artificial” soft bottom. These containers were sampled by divers over a one-year period to observe the development of the meiofauna population. The first settlement, mainly by nematodes, took place immediately after exposure, and six months later the population was stabilized. The meiofauna consists mainly of nematodes and harpacticoides. Biomass and density are generally lower than in the surrounding area. Only the harpacticoid fauna is well represented by different species and has more individuals per m2 than the surrounding area. Biological aspects of the specific features of the sediment containers, e. g. size and their distance to the sea bottom are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02189588
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  • 4
    Electronic Resource
    Electronic Resource
    Biometric studies on the bivalvesAstarte elliptica, A. borealis andA. montagui in Kiel Bay (Western Baltic Sea) (1985)
    Springer
    Helgoland marine research 39 (1985), S. 245-253 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The threeAstarte species were studied in June 1983 at two sites in Kiel Bay, “Süderfahrt” and “Schleimünde”, at 20 m depth. Shell length to live wet weight correlations are given for all three species; forA. elliptica also shell-free dry weight, shell dry weight, ash-free dry weight of the soft body and ash-free dry weight of the shell are recorded as functions of the shell length. In the logarithmic length/weight regression analysis the coefficients of slope forA. elliptica andA. borealis are 3. ForA. montagui, that coefficient is significantly greater than 3. Weight conversion factors, calculated forA. elliptica, revealed a mean weight composition of 31.5 % water in the mantle cavity and tissue water, 64.5 % shell ash, 2.1 % organic content of shell, 1.7 % organic content of the soft body and 0.4 % ash of the soft body. An isometric growth of shell length and shell breadth is confirmed forA. borealis, whileA. montagui exhibits positive allometric shell growth and changes its shape during life.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01992772
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructure of introvert and pharynx of Halicryptus spinulosus (priapulida) (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 206 (1990), S. 163-171 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The introvert of Halicryptus spinulosus bears three kinds of sensilla: buccal papillae, ordinary scalids, and dentoscalids. They are all characterized by bipolar monociliary receptor cells. The former two have apical openings at which the sensory cilia are in close contact with the ambient sea water. The pharyngeal teeth are composed of slender epithelial cells the tips of which are devoid of organelles and a thick cuticle. The anatomy of the muscle arrangement of the pharynx is described. Glands occur at the junction of the pharynx and midgut.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052060203
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    Paper (German National Licenses)
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