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  • 1
    Electronic Resource
    Electronic Resource
    A hydrodynamic study of a modified model of the Clarke Jet Net (1968)
    Springer
    Marine biology 1 (1968), S. 204-209 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A hydrodynamic study of a modified model of the Clarke Jet Net, a high speed plankton sampler, was made using a wind tunnel and an IBM 7040. Modifications allowed a somewhat larger amount of water filtered than in the original model. By adjusting the size of the net chamber exhaust (water control aperture), an average net chamber velocity of about 100 cm/sec could be obtained at any cruising speed. The curvature of the towing cable of the deep tow of a high speed sampler seemed to be determined mainly by the cable characteristics. The stability, vertical and horizontal, of the modified model was satisfactory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00347113
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Hydrodynamic and towing characteristics of a modified model of the Clarke Jet Net (1969)
    Springer
    Marine biology 2 (1969), S. 297-306 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a series of studies to develop an effective high speed plankton sampler, hydrodynamic research was carried out on a modified model of the Clarke Jet Net. A theoretical analysis of the motion of the sampler was made using an IBM 7040 computer, and test tows were made in an experimental ship tank and at sea. To maintain the roll angle of the sampler at approximately zero, a v-shape bridle was applied. A pair of towing holes should be selected for the particular range of towing velocity. The calculated longitudinal stability seemed good in all the cases examined. Towing tests in the ship tank at 2 to 3 m/sec revealed sufficient stability. The motion of the sampler at speeds higher than 3 m/sec can be assumed from hydrodynamic coefficients derived from the ship tank experiment. Towing-cable characteristics, assumed by computation, indicated that about 500 m at 6 kt and 1,000 m at 12 kt should be paid out to lower the sampler down to 100 m. The effect of the sampler on the cable is found only adjacent to it and is almost negligible beyond 50 m from it in depth. Results of sea tests at 6 and 9 kt confirmed the stability of the sampler. Examination of the catch suggested that the present model can be used, with some modifications, for the quantitative and qualitative sampling of large zooplankton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00355708
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Selective predation on mature male Byblis japonicus (amphipoda: Gammaridea) by the barface cardinalfish, Apogon semilineatus (1992)
    Springer
    Marine biology 114 (1992), S. 211-217 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In our study conducted in Shijiki Bay, Japan, in 1983 nocturnal barface cardinalfish (Apogon semilineatus) fed almost exclusively on mature males of the infaunal tube-dwelling gammarid Byblis japonicus. This predation pattern cannot be explained in terms of the sex composition of B. japonicus in the sediment, because mature males were the least abundant members of the population. Rather, this phenomenon may be explained by two alternative factors: diel vertical migration and size of prey. At night many gammarids, including B. japonicus, move up to the near-bottom water, and consequently become available to A. semilineatus, an epibenthos and/ or plankton feeder. Among these gammarids, juvenile B. japonicus and other gammarid species were more abundant than mature males, but were too small for A. semilincatus to prey on. Since mature B. japonicus males were the most abundant form of epibenthic and/or planktonic, large bodied prey present, the diet of A. semilineatus was limited almost entirely to these mature males. The sex ratio difference between B. japonicus individuals in the sediment and those in the near-bottom water indicated that vertical migration in this species has two functions: to assure the dispersal of juveniles and to allow mating contact for mature males.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349521
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    Paper (German National Licenses)
    Fulltext
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