相模湾平塚沖の貝類相－2011 年9 月と10 月の調査結果－

概要

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短報Mollusks and bottom sediment were simultaneously collected by dredging Sagami Bay off Hiratsuka at depths of 2 to 45 m on 7 September soon after the strong typhoon Talas and on 31 October 2011．In September，94 specimens belonging to 21 species were obtained：10 species of gastropods and 11 species of bivalves，whilst in October，272 specimens belonging to 8 species were obtained：4 species of gastropods and 4 species of bivalves．All were warm‐water species，19 of which are known only in Japan and 2 of which are distributed from Japan to equatorial regions．Although some harmful influence of the typhoon on the molluscan fauna was expected，no marked effect was recognized except at one station（st.1：40 m deep）near the mouth of the River Sagami, where the seafloor was temporarily covered with mud，which was transported by the Sagami during the typhoon．At theother stations，the mollusks obtained from each depth were basically the same as those in the investigation in 2010．Umbonium giganteum exclusively occupied the seafloor with finegrained sand around 3 m deep．Veremolpa micra and Nitidorellina minuta were dominant in fine‐grained sand from 10 to 20 m deep．Glycymeris imperialis was dominant accompanied by different kinds of gastropods in muddy very fine‐grained sand at depths of 20 to 30 m．
2012-06-30