BENTHOS RESEARCH
Online ISSN : 2186-4535
Print ISSN : 0289-4548
ISSN-L : 0289-4548
Volume 1993, Issue 44
Displaying 1-7 of 7 articles from this issue
  • TOSHIHIKO FUJITA
    1993 Volume 1993 Issue 44 Pages 1-17
    Published: March 25, 1993
    Released on J-STAGE: August 07, 2009
    JOURNAL FREE ACCESS
    Some ecological information about offshore demersal fish communities is reviewed. Research on the structure of fish communities is popular, and many works have been carried out in fresh water, coral reef, and coastal habitats. Studies of offshore demersal fish communities are relatively scarce and descriptive. Many commercially important species inhabit in offshore waters, and recently community-level studies have been required for the management of fishery stocks. Characteristics of the communities were described on some features, e. g., density, biomass, species diversity and rank-abundance diagram. Gradient analyses along water depth revealed some trends of such features characterizing the community structure. Many current studies examined the food of demersal fish. Two types of feeding guilds, benthic feeding and benthopelagic feeding, were recognized, and the latter was quantitatively important for energy input into demersal fish communities. Recent publications scrutinized the pattern of resource use examining the niche for food and space. Such works on resource partitioning showed both niche overlap and niche segregation by food, and little evidence indicated the existence of interspecific competition.
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  • HIROMICHI IMABAYASHI
    1993 Volume 1993 Issue 44 Pages 19-28
    Published: March 25, 1993
    Released on J-STAGE: August 07, 2009
    JOURNAL FREE ACCESS
    Population of a Penaeid shrimp Metapenaeopsis dalei in Suo-Nada, the Seto Inland Sea, was composed of the early and late cohorts. The carapace length of juveniles immediately after settlement exhibited a mode of 1.7mm, with a 95% confidence interval of 1.57 to 1.73mm. The late cohort settling in October was usually collected in shallower waters than the early cohort settling in September. The early cohort was suggested to migrate offshore with a decrease in temperature. In June, however, two cohorts seemed to spawn at the same area of 25m in depth. The highest value of growth rate was estimated at approximately 1.5mm/month from April to June, while no growth was observed below 13°C. The extremely low temperature also is considered to cause a large mortality to the late cohort.
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  • TAEKO KIMURA, HIDEO SEKIGUCHI
    1993 Volume 1993 Issue 44 Pages 29-40
    Published: March 25, 1993
    Released on J-STAGE: August 07, 2009
    JOURNAL FREE ACCESS
    Based on monthly sampling for three years on the tidal flats, some aspects of population dynamics of Musculista senhousia were examined. The spatio-temporal distribution of densities of the Musculista specimens indicated that the distribution was strongly patchy due to occurrence of dense colonies of the small-sized juveniles, and to their mass mortality caused by sporadic heavy rains coupled with typhoons. Therefore, the number and size of the cohorts showed considerable annual fluctuations. It can be concluded that the cohort establishment of M. senhousia in the flats does not depend directly on strength of the recruitment, while collapsing of the cohorts and/or failure of the recruits are caused by catastrophic episodes of physical disturbance.
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  • YOSHIHISA SHIRAYAMA, TERUAKI KAKU, ROBERT P. HIGGINS
    1993 Volume 1993 Issue 44 Pages 41-44
    Published: March 25, 1993
    Released on J-STAGE: August 07, 2009
    JOURNAL FREE ACCESS
    A new plastic frame, named HS-slide (HIGGINS -SHIRAYAMA slide), was devised for better microscopic observation of meiofaunal specimens from both sides of a glycerol-mounted slide. The frame has a rectangular hole of 16×22mm, and a rectangular depression of 23×25×1.0mm so as to have a flange of 2 to 3mm wide around the hole. The flange of the frame holds a coverslip of 22×24mm. A specimen is mounted on it, and covered by another coverslip of an appropriate size. This frame is made of acrylic resin and resistant to most organic solvent, e.g., xylene, often used as a thinner of canada balsam. The HS-slide was found to have some advantages over the Cobb aluminum frame conventionally used for making a microscopic slide with two coverslips. The HS-slide was solid enough to resist bending or twisting, and only a slight focusing was needed when it was reversed to observe a nematode specimen from another side. Judging from these facts, the HS-slide was considered to be a useful new device for microscopic observation of meiofaunal organisms.
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  • YOSHITAKE TAKADA
    1993 Volume 1993 Issue 44 Pages 45-55
    Published: March 25, 1993
    Released on J-STAGE: August 07, 2009
    JOURNAL FREE ACCESS
    Knowledge on the abundance of epilithic microalgae is necessary to understand the ecology of grazers properly. But, quantitative sampling of microalgae on the natural rock surface is difficult and is prone to wide variations. In this study, I used natural rock tile (commonly called as "Amakusa touseki") and two types of ceramic tiles of size 10×10 cm as artificial substrata to compare the several methods of extraction of chlorophyll. Among the three types of tiles studied, rock tiles recorded highest concentration of chlorophyll contents. The variation of chlorophyll contents within the rock tile was small and was within the range of chlorophyll contents observed on the natural boulders. In the upper and the middle intertidal zones, chlorophyll contents attained constant values within six weeks. But in the lower zone, due to the growth of macroalgal spores, the chlorophyll contents seldom increased steadily and hence the constant values could not be obtained within the period of observations. Comparison of sampling methods showed that brushing and scraping of rock tile surface were less effective than immersing the substratum directly in the extraction liquid in a polyethylene bag (polyethylene-bag method). Among the two extraction liquids tested, the 90 ethanol gave better extraction of chlorophyll than the 90% acetone. After compiling the whole results obtained, it is concluded that the "Amakusa touseki" rock tile is a good substratum to monitor the chlorophyll contents of epilithic microalgae, and 90% ethanol and polyethylene-bag method is the best suitable method for the extraction of chlorophyll.
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  • TAIJI KIKUCHI
    1993 Volume 1993 Issue 44 Pages 57-69
    Published: March 25, 1993
    Released on J-STAGE: August 07, 2009
    JOURNAL FREE ACCESS
    Patulin contamination in apple-based products in Japan was surveyed, and the risk of patulin in Japan was estimated. A total of 252 samples of apple-based products, collected from market or juice plants in Japan during the years 1996 to 2001, were examined for patulin with the method of analysis using GC/MS; the recovery was 101 %, and limit of confirmation was 5μg/kg. Patulin was detected in 15.6 % of commercial apple juices in the range of 5 to 42μg/kg. No commercially available apple juice contained more than 50μg/kg of patulin, the proposed future regulatory limit in Japan. In 81 % of apple juice concentrates, patulin was detected in the range of 5 to 670μg/kg. The daily intake of patulin for mean of all population in Japan is quite below the provisional maximum tolerable daily intake (PMTDI) indicated by JECFA, 0.4μg/kg body weight/day. The risk of patulin is considered to be negligible in Japan.
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  • 1993 Volume 1993 Issue 44 Pages 71
    Published: March 25, 1993
    Released on J-STAGE: August 07, 2009
    JOURNAL FREE ACCESS
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