日本ベントス学会誌
Online ISSN : 1883-891X
Print ISSN : 1345-112X
ISSN-L : 1345-112X
67 巻, 2 号
選択された号の論文の5件中1~5を表示しています
原著論文
  • 堤 裕昭, 野村 龍之介, 田上 貴文, 小森 田智大, 岩崎 敏治, 藤森 隆美
    原稿種別: 原著論文
    2013 年 67 巻 2 号 p. 47-55
    発行日: 2013/06/25
    公開日: 2014/09/11
    ジャーナル フリー
    On the Midori River Tidal Flats, which face Ariake Bay in Kumamoto, Kyushu, Japan, the originally sandy sediment has recently become widely covered with muddy byssal mats created by mytilid musseles, Musculista senhousia. Since the formally dominant bivalves in the macrobenthic community, such as Tapes (Ruditapes) philippinarum, Mactra veneriformis, and others, favor sandy sediment as their habitat, they have been excluded by the development of the muddy byssal mats. In this study, sediment covered such mats on the tidal flats was dug up to a depth of about 1 m with a power shovel fixed to a barge, with the aim of eliminating the muddy byssal mats, and restoring sandy surface sediment there. This operation was successful, and soon afterwards the two bivalves, T. (R.) philippinarum, and M. veneriformis, again became dominant in the macrobenthic community. The effect of digging up the sediment lasted through the year-long course of this study even though M. senhousia twice had a chance for dense recruitment of juveniles through reproduction.
  • 小林 哲
    原稿種別: 原著論文
    2013 年 67 巻 2 号 p. 56-63
    発行日: 2013/06/25
    公開日: 2014/09/11
    ジャーナル フリー
    The reproductive ecology of the victorious moon crab Matuta victor (Matutidae, Brachyura, Crustacea) was surveyed on an open sandy beach of the Genkai-nada Sea in Nata, Fukuoka City, Japan, between June, 2008, and October, 2009. Crabs were collected in the shallow subtidal zone (<50 cm depth) during daytime by hand or with hand nets and the condition of their gonads and embryos was checked. Large-sized M. victor, including juveniles and adults with a carapace width (CW) of >17 mm were present only from May to October on this beach, and they probably migrated elsewhere between November and April. CW frequency distributions showed a clear sexual distinction: females were composed of juveniles (17.9–31.8 mm CW) and adults with mature exoskeleton (31.7–44.6 mm CW), but males (21.6–56.8 mm CW) included adults of >41.9 mm CW showing gonadal development. Ovigerous females were observed between late May and early September. Embryonic development indicated that eggs were spawned mostly between May and August and that they hatched between July and September. Ovigerous adults showed no gonadal development, and this suggests that females oviposit only once in one reproductive season. In both sexes, gonads markedly developed between May and July and regressed after August. In sum, in the Genkai-nada Sea, adults of M. victor appear to inhabit the shallow subtidal zone between early summer and autumn and reproduce sparingly in summer, spawning only once within one reproductive season. Confirmation of the whereabouts and reproductive state of the crabs during the colder months is essential to comprehend the complete reproductive ecology of M. victor in the temperate zone.
  • 逸見 泰久, 三好 美由紀, 川内 識史
    原稿種別: 原著論文
    2013 年 67 巻 2 号 p. 64-72
    発行日: 2013/06/25
    公開日: 2014/09/11
    ジャーナル フリー
    電子付録
    Pen shells, Atrina spp., were important marine product in the northern Ariake Sea until recent years, but most of the pen shell populations have collapsed over the past two decades. In the present study, recruitment, growth, and mortality were compared among three pen shell populations, at Site A (intertidal zone), Site B (upper subtidal zone, 3 m in depth), and Site C (subtidal zone, 7 m in depth) in the northeast fishery zone of the Ariake Sea from 2000 to 2006. The maximum mortality rate (maximum proportion of dead shells on each sampling date) was low at Site A (12.8%) and Site B (7.8%). On the other hand, at Site C, most pen shells have died, with undamaged shells mainly from spring to summer and, in most years, a maximum mortality rate of over 80% present. At Site C, shell density decreased greatly during the study period, but it was much higher than at Site A or B. Growth was slower and the soft body weight was lower at Site C than at Sites A and B, but the seasonal pattern of relative gonad weight was not very different among the three sites. These results suggested that there has been a deterioration of habitat conditions at Site C and that excessive reproductive investment under bad conditions might have led to the massive die-offs there. Although the direct cause of these die-offs is unclear, it is certain that degradation of sea-bottom conditions as a result of, e.g., hypoxia, increase in sulfide concentration, and decrease in grain size of the sediment, affects the survival of pen shells directly.
  • 岩崎 敬二
    原稿種別: 原著論文
    2013 年 67 巻 2 号 p. 73-81
    発行日: 2013/06/25
    公開日: 2014/09/11
    ジャーナル フリー
    The distribution of the non-indigenous mytilid bivalve Xenostrobus securis (Lamarck, 1819), native to Australasia, was investigated through a survey of 325 sites along the Japanese coast of the Sea of Japan from 2006 to 2011. The species was found at 20 sites from Toyama Prefecture westwards (Toyama Port and Shin-minato Fishing Port in Toyama Prefecture; Kanazawa Port and the Daishoji River in Ishikawa Prefecture; the Inokuchi River, Lake Kugushi, and Lake Suigetsu in Fukui Prefecture; the Takeno River in Hyogo Prefecture; Lake Nakaumi in Tottori and Shimane Prefectures; and Dokai Bay and Hakata Bay in Fukuoka Prefecture), all of which were located in brackish-water areas such as lagoons, river mouths, and the innermost parts of large ports. Size distributions of the collected mussels suggest that breeding populations have been established at eight sites. Although X. securis was not found at 86 sites from Niigata Prefecture northwards, water temperature regimes in the native and invaded areas suggest that it may eventually spread as far north as the southern end of Hokkaido.
特集
  • 山口 啓子, 倉田 健悟, 園田 武, 瀬戸 浩二
    原稿種別: 特集
    2013 年 67 巻 2 号 p. 82-95
    発行日: 2013/06/25
    公開日: 2014/09/11
    ジャーナル フリー
    Bivalve community structure and its relation to the environmental factors in Lake Nakaumi, southwest Japan were examined for the surveyed data of 1997 and 2006. The brackish mussel Musculista senhousia was the predominant species of Lake Nakaumi in both years. Lake Nakaumi was divided into two areas, Honjo Area and Nakaumi Area, by the construction of reclamation dikes in the 1970s. The community and environmental features of the two areas were different. The bivalve community of Honjo Area was quite simple, while that of Nakaumi Area had some varieties. The homogeneity of salinity in Honjo Area was supposed to be the reason for the simple community structure. The bivalve community in Lake Nakaumi was divided into four types. These types were influenced by the frequency of the dominant species, primarily Musculista senhousia, and secondarily other dominant species. The spatial distribution of the community types changed from 1997 to 2006, and the area of no bivalves markedly increased in Honjo Area. The organic material of the sediment in Honjo Area apparently increased after the construction of dikes. This was supposed to increase the consumption of dissolved oxygen and expand the area of anoxia and no bivalves in Honjo Area.
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