BENTHOS RESEARCH
Online ISSN : 1883-8901
Print ISSN : 0289-4548
ISSN-L : 0289-4548
Volume 58, Issue 1
Displaying 1-7 of 7 articles from this issue
  • Mana Yamada, Keiji Wada, Terufumi Ohno
    2003 Volume 58 Issue 1 Pages 1-6
    Published: June 30, 2003
    Released on J-STAGE: November 11, 2011
    JOURNAL FREE ACCESS
    Abstract: The occurrence of the green alga Cladophora conchopheria on shells of the intertidal gastropod Turbo coronatus coreensis was examined at a bay in central Japan. The shells were consistently fouled predominantly by C. conchopheria. Observation of cross-sections of the shells by SEM revealed that false roots of C. conchopheria penetrated through the periostracum and into the outer ostracum of the shells. Field observations showed that C. conchopheria was uncommon or absent in the innermost parts of the bay, where the substrata were composed partially of mud and T. coronatus coreensis was common. A transplant experiment revealed that the alga could not newly colonize shells or maintain their colonization at one of the innermost stations. After the death of the snails, the abundance of C. conchopheria on shells did not change for3months and then decreased gradually, probably as a result of tearing of the periostracum layer. We saw no new algal colonization on dead snail shells even after8months. Most colonization of living snails occurred on the shell part nearest to the aperture, indicating that algal colonization occurred primarily in the area of the new shell growth.
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  • Carolus P. Paruntu, Mutsunori Tokeshi
    2003 Volume 58 Issue 1 Pages 7-14
    Published: June 30, 2003
    Released on J-STAGE: November 11, 2011
    JOURNAL FREE ACCESS
    Abstract: The reproductive characteristics of an intertidal gastropod, Nerita japonica(Dunker), were investigated among eight local populations occurring in different intertidal habitats of Amakusa Shimoshima Island, western Kyushu, Japan. There was significant variation in the morphometry of egg capsules and embryos between rocky shore and stony shore populations of N. japonica, with the rocky shore populations having larger capsule sizes than stony shore populations. In five out of eight populations, fecundity(number of embryos in an egg capsule)increased significantly with an increase in egg capsule size and decreased with mean embryo size. The data showed for the first time that fecundity and egg capsule size, but not embryo size, are related to adult body size among local populations of N. japonica. The present study demonstrates that body size and reproductive characteristics of N. japonica may vary markedly over even small geographic distances. Such variability in the basic traits of a species must have important implications for their life history Strategy.
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  • Tomoyuki Komai, Shinji Mishima
    2003 Volume 58 Issue 1 Pages 15-30
    Published: June 30, 2003
    Released on J-STAGE: November 11, 2011
    JOURNAL FREE ACCESS
    Abstract: The lectotype of Pagurus minutus Hess, 1865 and the syntypes of Pagurus dubius(Ortmann, 1892)were compared. Pagurus minutus has proved to be a senior subjective synonym of Pagurus dubius. Hess's species is redescribed and illustrated in detail based on the type material and an abundance of additional specimens from Japan, Korea, and Taiwan. Notable intraspecific variations are seen in the right cheliped and dissimilarity of the third pereopod. In males, a tendency toward elongation of the right cheliped accompanied with reduction of the armature is found. The degree of dissimilarity in the third pereopods is stronger in females than in males. Pagurus minutus is most similar to P. filholi(De Man, 1887)and P. samuelis(Stimpson, 1858). The elongate dactyli of the second and third pereopods and the coloration in life immediately distinguish P. minutus from these other two species.
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  • Monthon Ganmanee, Teruyoshi Narita, Hideo Sekiguchi
    2003 Volume 58 Issue 1 Pages 31-42
    Published: June 30, 2003
    Released on J-STAGE: November 11, 2011
    JOURNAL FREE ACCESS
    Abstract: Some aspects of the population dynamics of the asteroid, Luidia quinaria, in Ise Bay, central Japan, were examined in relation to environmental factors based on data collected from 1993 to 1999. Abundance of the asteroid was significantly different between seasons and between years. The main recruitment episode occurred in autumn every year, although small-scale recruitment was observed in spring. Interannual variation in the abundance of new recruits was marked, being most intense in 1996 and 1997. Severity and period of occurrence of oxygen-poor water(with a dissolved oxygen content at the bottom of less than 3ppm), which develops every summer, play an important role in determining the population structure and growth of asteroids of the 0+ and 1+ age classes. The von Bertalanffy growth equation provided the best fit to our data.
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  • Kenji Kaneko, Michio Omori
    2003 Volume 58 Issue 1 Pages 43-49
    Published: June 30, 2003
    Released on J-STAGE: November 11, 2011
    JOURNAL FREE ACCESS
    Abstract: We describe predator-prey relationships related to diel and tidal migrations based on observations of the distributions of macrobenthic animals over24hours along sandy beach slopes in two locations of Sendai Bay, northern Japan. The macrobenthic communities were largely comprised of Excirolana chiltoni(Isopoda: Cirolanidae), Haustorioides japonicus(Amphipoda: Dogielinotidae), and Archaeomysis kokuboi and A. vulgaris(Mysidacea: Gastrosaccinae). Excirolana chiltoni occurred in the swash zone at high tide and its distribution did not shift with the tidal cycle. On the other hand, H. japonicus, A. kokuboi, and A. vulgaris, located in the swash zone, shifted with the tides. Their distributions overlapped with that of E. chiltoni only at high tide. Gut content analysis suggested that A. kokuboi and A. vulgaris mainly fed on copepods at night, and that H. japonicus mainly fed on particulate detritus; E. chiltoni mainly fed on the mysidaceans, H. japonicus, and stranded carrion. These facts suggest that a food chain starts with detritus and copepods in the swash zone and the sublittoral zone, passes through H. japonicus or mysidaceans in the swash zone, and leads finally to E. chiltoni in the upper littoral zone. Judging from the fact that the overlap of the distributions of macrobenthic animals was formed by their tidal and diel migrations along the beach slope, it can be concluded that the predator-prey relationships in sandy-beach communities are maintained by the tidal and diel migrations of macrobenthic animals.
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  • Yusli Wardiatno, Katsumasa Shimoda, Kazuki Koyama, Akio Tamaki
    2003 Volume 58 Issue 1 Pages 51-73
    Published: June 30, 2003
    Released on J-STAGE: November 11, 2011
    JOURNAL FREE ACCESS
    Abstract: In the Ariake-Sound estuarine system, western Kyushu, Japan, two congeneric callianassid shrimps, Nihonotrypaea harmandi and N. japonica, which inhabit deep-reaching burrows on intertidal sandflats, generally occur separately along salinity gradient. The former and latter species appear mainly in(mixo-)euhaline and mixo-polyhaline waters, respectively. The two species co-occur in a restricted water range of intermediate salinity. The present study examined the spatial variation in density of the two species along the intertidal gradient on four sandflats selected from that water range, in relation to various environmental parameters including elevation, duration of exposure, sediment grain-size composition, sediment thickness and firmness, and subsurface-water salinity, temperature, oxygen concentration, and redox potential. On the respective sandflats in the exclusive occurrence ranges, each species inhabited the entire sandflat. In their co-occurrence range, N. japonica and N. harmandi separately inhabited the upper and lower shores, as a rule. Neither subsurface-water salinity nor temperature variations along the intertidal gradient could explain this zonation pattern. In contrast, the other environmental parameters varied in a shore-level-specific way, and corresponded closely to the zonation. In general, N. japonica occupied a broader fundamental niche, which would be associated with the harsher conditions of its primary habitat, i. e., extensive tidal flats in the middle estuary. In particular, a greater tolerance of this species for hypoxic conditions during a longer exposure period was strongly suggested. The abundance pattern of the two species also suggested the competitive dominance of N. harmandi, which might result in the exclusion of N. japonica from the lower shore.
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  • Teruyoshi Narita, Moazzem Hossain, Hideo Sekiguchi
    2003 Volume 58 Issue 1 Pages 75-85
    Published: June 30, 2003
    Released on J-STAGE: November 11, 2011
    JOURNAL FREE ACCESS
    Abstract: Due to recent eutrophication, oxygen-poor water develops annually near the bottom of Ise Bay, central Japan, in summer to autumn. This study examined seasonal and interannual variations in the abundance, biomass and distribution of megabenthos in the bay over a 7-year period to see if they were affected by this oxygen-poor water. The biomass of megabenthos, as well as the abundance/biomass of the dominant megabenthos species, drastically decreased during warm periods when oxygen-poor water developed, and increased from autumn to spring of the following year when oxygen-poor water no longer occurred. Seasonal variations in the spatial distributions of dominant species changed closely with the development of oxygen-poor water. The dominant taxa among the megabenthos(mainly echinoderms and crustaceans)and the dominant species within each dominant taxon changed drastically during the study. For crustaceans, the dominant species from 1996 to 1998(Paradorippe granulata and Cancer gibbosulus)differed greatly from those dominant from 1993 to 1994(Carcinoplax vestita, Oratosquilla oratoria and Charybdis bimaculata). This change may have been related to the matching/mismatching of spawning and larval recruitment events of each dominant taxon or species with the development and dissolution of oxygen-poor water in the bay.
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