すஅᓥࡢ₻㛫ᖏᾏὒ⏕≀┦୰㔝ᬛஅ ࠊ  㝯୍ Marine organisms in the intertidal zone of Nishinoshima IslandTomoyuki NAKANO1* & Ryuichi MINATO2
1. ி㒔኱Ꮫࣇ࢕࣮ࣝࢻ⛉Ꮫᩍ⫱◊✲ࢭࣥࢱ࣮℩ᡞ⮫ᾏᐇ㦂ᡤ㸦ࠛ649-2211 ࿴ḷᒣ┴す∹፝㒆ⓑ὾⏫ 459㸧Seto Marine Biological Laboratory, Field Science and Education Center, Kyoto
University, 459 Shirahama, Nishimuro, Wakayama 649-2211, Japan.
2. ⮬↛⎔ቃ◊✲ࢭࣥࢱ࣮㸦ࠛ130-8606 ᮾி㒔ቚ⏣༊Ụᮾᶫ 3-3-7㸧
Japan Wildlife Research Center, 3-3-7 Kotobashi, Sumida, Tokyo 130-8606, Japan.
*nakano.tomoyuki.2a@kyoto-u.ac.jp
せ᪨2019 ᖺ 9 ᭶࡟すஅᓥࡢ₻㛫ᖏᾏὒ⏕≀┦ࡢㄪᰝࢆ⾜ࡗࡓࠋᮏㄪᰝ࡛ࡣ㈅㢮 4 ✀ࢩ࣡࢞ࢧࠊࢡ࣐ࣟ࢝ࣛࢶ࢞࢖ࠊࢥ࢘ࢲ࢝ࢱ࣐࢟ࣅࠊ࢜࢞ࢧ࣡ࣛࢱ࣐࢟ࣅࠊ⏥Ẇ㢮 2 ✀࢜࢜࢖࣡࢞ࢽࠊ࢜࢜࢝ࢡࣞ࢖࣡࢞ࢽࠊ㨶㢮 1 ✀࢔࢜ࣔࣥࢠ࣏ࣥࢆ☜ㄆࡋࡓࠋࡇࡢ࠺
ࡕࠊࢩ࣡࢞ࢧ࡜ࢡ࣐ࣟ࢝ࣛࢶ࢞࢖ࡣᑠ➟ཎㅖᓥ࿘㎶ᅛ᭷✀࡛࠶ࡿࡀࠊࡑࢀ௨እࡢ✀ࡣᗈᇦศᕸ✀࡛࠶ࡗࡓࠋ࢜࢜࢖࣡࢞ࢽ௨እࡣಶయᩘࡀ㠀ᖖ࡟ᑡ࡞ࡃࠊᄇⅆࡢᙳ㡪࡛₻㛫ᖏᾏὒ⏕≀┦ࡣ୍ᗘ⤯⁛ࡋࡓ࡜⪃࠼ࡽࢀࡿࠋࡑࡢᚋࠊᾏὶศᩓ࡟ࡼࡾすஅᓥ࡬ศᩓࡋࠊ௒ࡲࡉ࡟㑄⛣ࡀጞࡲࡗࡓࡶࡢ࡜⪃࠼ࡽࢀࡿࠋ࣮࣮࢟࣡ࢻ ⛣ධࠊᑠ➟ཎㅖᓥࠊ⠇㊊ື≀ࠊ㌾యື≀ࠊศᩓ㸯㸬ࡣࡌࡵ࡟㐣ཤ࡟኱㝣࡜㝣⥆ࡁ࡟࡞ࡗࡓࡇ࡜ࡢ↓࠸ᾏὒᓥࡣࠊᾏὒ⏕≀ᆅ⌮ࡸ✀ศ໬ࡢ◊✲ࢆ⾜࠺ୖ࡛㠀ᖖ࡟㔜せ࡛࠶ࡾࠊ࢞ࣛࣃࢦࢫㅖᓥࡸࣁ࣡࢖࡞࡝࡛ከࡃࡢ◊✲ࡀ࡞ࡉࢀ࡚࠸ࡿ(e.g., Kay & Palumbi, 1987; Paulay & Starmer, 2011; MacLeod et al., 2015)ࠋ᪥ᮏ
࡟࠾࠸࡚ࡣࠊᮏᕞ࠿ࡽ༡࡟⣙ 1,000kmࠊἈ⦖࠿ࡽᮾ࡬⣙ 1,300km ࡟఩⨨ࡍࡿᑠ➟ཎㅖᓥࡀᾏὒᓥ࡛࠶ࡾࠊᵝࠎ࡞⏕≀࡟࠾࠸࡚ᅛ᭷✀ࡀከᩘሗ࿌ࡉࢀ࡚࠸ࡿ(e.g.,Springer et al., 1995; Satake & Cai, 2005; Chiba et al., 2007)ࠋࡋ࠿ࡋ࡞ࡀࡽࠊᾏ⏘ࡢᕳ− 109 −

㈅㢮ࡣᑠ➟ཎㅖᓥ࠿ࡽ 1,031 ✀ࡀሗ࿌ࡉࢀ࡚࠸ࡿࡀࠊᑠ➟ཎᅛ᭷✀ࡣᩘ✀࡟࡜࡝ࡲࡿ(Fukuda, 1993, 1994, 1995)ࠋࡇࢀࡣᾋ㐟ᗂ⏕᫬ࡢᾏὶศᩓࡶࡋࡃࡣᡂయࡀᾏⲡࡸὶ
ᮌ࡞࡝࡟஌ࡗ࡚㐠ࡤࢀࡿࣛࣇࢸ࢕ࣥࢢ࡟ࡼࡾࠊ㐲ࡃ㞳ࢀࡓᆅᇦ࡟ࡶศᩓࡀྍ⬟࡛࠶ࡿࡇ࡜ࢆ♧ࡋ࡚࠸ࡿ(Fraser et al., 2017; González-Wevar et al., 2017)ࠋᾋ㐟ᗂ⏕ᮇࡀ㛗࠸✀ࡀᾏὒᓥ࡟㐍ฟ࡛ࡁࡓ㝿࡟ࡣ༢࡞ࡿᗈᇦศᕸ✀࡜࡞ࡿࡀࠊᾋ㐟ᗂ⏕ᮇࡀ▷࠸✀ࡀ༑ศ࡟㝸㞳ࡉࢀࡓᾏὒᓥ࡟㐍ฟ࡛ࡁࡓ㝿࡟ࡣࠊᅛ᭷໬ࡀಁࡉࢀࡿ࡜⪃࠼ࡽࢀ࡚࠸
ࡿࠋNakano et al. (2009)࡛ࡣࠊᑠ➟ཎㅖᓥ࡟ᅛ᭷ࡢ࢝ࢧ࢞࢖ Cellana mazatlandica ࡜ࢩ࣡࢞ࢧ Cellana radiata enneagona ࡟ࡘ࠸࡚ศᏊ⣔⤫ゎᯒࡀ⾜ࢃࢀࠊࡑࡢ✀ศ໬ࡀ㆟ㄽࡉࢀࡓࠋࡑࡢ⤖ᯝࠊ᪥ᮏࡢ ᖏᇦ࡟ᗈࡃศᕸࡍࡿ࣋ࢵࢥ࢘࢞ࢧ Cellana grata ࡜࣓ࣚ࢞࢝ࢧ Cellana toreuma ࡀࡑࢀࡒࢀ㏆⦕✀࡜᥎ᐃࡉࢀࡓࠋࡲࡓศᒱᖺ௦ࡢ᥎ᐃࡢ
⤖ᯝࠊ➨ᅄ⣖࡟ⅆᒣάືࡶࡋࡃࡣịἙᛶᾏỈ‽ኚື࡟ࡼࡾࠊఀ㇋ㅖᓥ࠿ࡽᑠ➟ཎㅖᓥࡢ㛫࡟࠶ࡿ୐ᓥʊ◲㯤ᓥᾏᕊ࡟࠾࠸࡚᪂ࡓ࡞ᓥࡀฟ⌧ࡋࠊࡑࢀࡽࡢᓥࢆ㣕ࡧ▼(ࢫࢸࢵࣆࣥࢢࢫࢺ࣮ࣥ)࡜ࡋ࡚♽ඛ✀ࡀᮏᕞ࠿ࡽᑠ➟ཎㅖᓥ࡬Ώࡗࡓ࡜⪃࠼ࡽࢀࠊࡑࡢ
ᚋࡢࡉࡽ࡞ࡿⅆᒣάືࡸᾏỈ‽ࡢୖ᪼࡟క࠸ᑠ➟ཎㅖᓥ࡟ྲྀࡾṧࡉࢀࠊᅛ᭷໬ࡋࡓ࡜᥎ᐃࡉࢀࡓࠋᾏὒᓥࡢ⏕≀✀ࡢ㉳※ࡣࠊከࡃࡣ⏕≀┦ࡢẚ㍑ࡸศᏊ⣔⤫ゎᯒ࡟ࡼࡾ᥎ᐃࡉࢀࡿࡇ࡜ࡀከࡃࠊ᪂ࡋࡃฟ⌧ࡋࡓᓥ࡟᪂ࡋࡃ⏕ࡁ≀ࡀ㐍ฟࡋ࡚ࡃࡿ▐㛫ࢆほᐹࡍࡿᶵ఍ࡣࡇࢀࡲ࡛࡟࡯࡜ࢇ࡝࡞࠿ࡗࡓࠋすஅᓥࡣᑠ➟ཎㅖᓥࡢ∗ᓥࡢす᪉⣙ 130km ࡟఩⨨ࡋ࡚࠸ࡿࠋࡇࡢᓥࡣ 1973㹼1974
ᖺࠊ2013 ᖺ㹼2015 ᖺࠊ2017 ᖺࠊ2018 ᖺ࡜⧞ࡾ㏉ࡋᄇⅆάືࡀ☜ㄆࡉࢀ࡚࠾ࡾࠊ1973ᖺ࠿ࡽࡢᄇⅆ࡛ࡣすஅᓥࡢ༡ᮾ࡟᪂ᓥࡀฟ⌧ࡋࠊ᭱⤊ⓗ࡟すஅᓥ࡜㝣⥆ࡁ࡜࡞ࡗࡓࠋ
2013 ᖺ࠿ࡽࡢᄇⅆάື࡛ࡶ᪂ᓥࡀฟ⌧ࡋࠊࡑࡢᚋࡶ࡜ࡶ࡜࠶ࡗࡓᓥ(ᪧᓥ)ࢆ㣧ࡳ㎸ࡳ࡞ࡀࡽ㠃✚ࢆᣑ኱ࡉࡏࠊ᪂ࡋ࠸ᓥ࡜࡞ࡗࡓࠋᓥࡢ୰࡯࡝࡟ᪧᓥࡀ୍㒊ṧࡿࡀࠊᓥࡢ඲࿘ࡣ඲࡚⁐ᒾ࡟ᾐ㣗ࡉࢀࠊすஅᓥࡢ⏕≀┦ࡣ࡯࡜ࢇ࡝ᾘኻࡋࡓ࡜⪃࠼ࡽࢀࡿࠋࡑࡢࡓࡵࠊすஅᓥࡣ᪂ࡋࡃฟ⌧ࡋࡓᾏὒᓥ࡜ᤊ࠼ࡿࡇ࡜ࡀ࡛ࡁࠊ⏕ែ⣔ࡢᙧᡂ㐣⛬ࢆほ ࡍࡿᶵ఍ࢆᥦ౪ࡋ࡚࠸ࡿࠋᮏㄪᰝ࡛ࡣࠊ⎔ቃ┬࡟ࡼࡿ௧࿴ඖᖺᗘすஅᓥ⥲ྜᏛ⾡ㄪᰝ࡜ࡋ࡚ྛᑓ㛛ศ㔝࡟࠾ࡅࡿ◊✲⪅࡟ࡼࡗ࡚ㄪᰝ㝲ࢆ⤖ᡂࡋࠊ2019 ᖺ 9 ᭶ 1᪥㹼11 ᪥࡟ㄪᰝࢆ⾜ࡗࡓࠋⴭ⪅ࡽࡣ₻㛫ᖏ⏕≀ᢸᙜ࡜ࡋ࡚ㄪᰝ࡟ྠ⾜ࡋࡓࠋᮏ◊✲ࡢ┠ⓗࡣࠊ2013 ᖺ࠿ࡽ⧞ࡾ㏉ࡋ࠾ࡁࡓᄇⅆάືࡀ₻㛫ᖏ⏕≀┦࡟୚࠼ࡓᙳ㡪ࢆ᫂ࡽ࠿࡟ࡍࡿࡇ࡜࡜ࠊ⌧ᅾࡢすஅᓥ࡟࠾ࡅࡿᾏὒ⏕≀ࡢ㑄⛣ࡢึᮇ≧ែࢆグ㘓ࡍࡿࡇ࡜࡛࠶ࡿࠋ㸰㸬ᮦᩱ࡜᪉ἲㄪᰝࡣすஅᓥࡢすഃ࡟ᗈࡀࡿすஅ὾ࠊ༡す㒊࡟ᗈࡀࡿ༡す὾ࡢ 2 ᆅⅬ࡛⾜ࡗࡓ(ᅗ 1)ࠋྛᆅⅬ࡟࠾࠸࡚ࠊ₻㛫ᖏ࠿ࡽ㣕ἓᖏ࡟࠿ࡅ࡚⏕ᜥࡋ࡚࠸ࡿᾏὒ⏕≀ࢆグ㘓ࡋࡓࠋὸᾏᇦࡢㄪᰝ࡟ࡘ࠸࡚ࡣࠊᓥ࿘㎶ࡢ₻ὶࡀ㏿࠸ࡓࡵࠊ㐟Ὃ࡟ࡼࡿㄪᰝࡣ⾜− 110 −ᅗ 1㸬すஅᓥ࡜ㄪᰝᆅ(๓㔝࣭ྜྷᮏࠊ2020 ࡢᅗ 2 ࢆᨵኚ)Fig. 1. Map of Nishinoshima Island and the survey sites (Figure modified from Fig.2 in
Maeno & Yoshimoto, 2020)ࢃ࡞࠿ࡗࡓࠋࢧࣥࣉࣜࣥࢢ࡟ࡘ࠸࡚ࡣࠊ୍ḟ㑄⛣᭱ึᮇࡢᐃ╔ಶయࢆ᥇㞟ࡍࡿࡇ࡜ࡣḟࡢ෌⏕⏘ࡢᶵ఍ࢆῶࡽࡍྍ⬟ᛶࡀ࠶ࡿ஦࠿ࡽࠊ᥇㞟ಶయᩘࡣ᭱ᑠ㝈࡟࡜࡝ࡵࡓࠋ㸱㸬⤖ᯝ࡜⪃ᐹ㸱㸫㸯㸬ᆅᙧ࡜⏕ᜥ⎔ቃ すஅᓥࡣࠊⅆ○ୣࡼࡾ 2013 ᖺ࠿ࡽ 2018 ᖺ࡟࠿ࡅ࡚」ᩘᅇ࡟࠿ࡅ࡚ᄇฟࡋࡓ⁐ᒾ࡟そࢃࢀࠊࡑࢀࡽࡀᾏᓊ⥺࡟ࡲ࡛㐩ࡋ࡚࠸ࡿ(ᅗ 1)ࠋࡑࢀࡽ⁐ᒾࡢ㛫࡟ࠊᾐ㣗࡟ࡼࡗ࡚సࡽࢀࡓ὾ࡀ࠸ࡃࡘࡶⅬᅾࡍࡿࠋすஅ὾ࡣࠊすஅᓥࡢ୰࡛ࡶ᭱ࡶ኱ࡁ࠸὾
ࡢ୍ࡘ࡛ࠊ၏୍ࠊᪧᓥ࡟㠃ࡋ࡚࠸ࡿ὾࡛࠶ࡿࠋࡇࡢ὾ࡢ໭ഃࡣ 2015 ᖺࠊ༡ഃࡣ2017 ᖺ࡟ᄇฟࡋࡓ⁐ᒾሢ࡟௙ษࡽࢀ࡚࠸ࡿ(ᅗ 2A, B)ࠋ὾ࡣ⁐ᒾࡀᾐ㣗ࡉࢀ࡚࡛ࡁࡓ⎰♟὾࡜࡞ࡗ࡚࠸ࡿࡀࠊሙᡤ࡟ࡼࡗ࡚♟ࡢ኱ࡁࡉࡀ␗࡞ࡗ࡚࠸ࡓࠋ὾୰ኸ㒊ࡣᩘ cm㹼10cm ⛬ᗘࡢ኱ࡁࡉࡢ♟ࡀከ࠸ࡶࡢࡢ(ᅗ 2A)ࠊ༡ഃ࡛ࡣ 60㹼70cm ⛬ᗘࡢ♟ࡀከࡃ࡞ࡗ࡚࠸ࡓ(ᅗ 2B)ࠋࡑࢀ࡜ࡣ㏫࡟ࠊ໭ഃ࡛ࡣࡼࡾ⣽࠿࡞◁฼὾࡜࡞ࡗ࡚࠸
ࡓ(ᅗ 2C)ࠋ༡す὾ࡣࠊ2017 ᖺ࡟ᄇฟࡋࡓ⁐ᒾ࡛௙ษࡽࢀࡓ὾࡛࠶ࡾࠊすஅ὾ࡼࡾࡶ᪂ࡋ࠸⁐ᒾ࡛ᵓᡂࡉࢀ࡚࠸ࡿࠋ༡す὾ࡢᾏᓊ⥺ࡣẚ㍑ⓗ୍ᵝ࡞ 10㹼30cm ⛬ᗘࡢ♟὾࡛ᵓᡂࡉࢀ࡚࠸ࡓࡀ(ᅗ 2E, F)ࠊᾏᓊ⥺࠿ࡽᓥ୰ኸ㒊࡟ྥ࠿ࡗ࡚ࠊ♟὾࠿ࡽ◁− 111 −
ᅗ 2㸬ㄪᰝᆅࡢᆅᙧ࡜⎔ቃ
A. すஅ὾୰ኸ࠿ࡽ໭ഃࠋB. すஅ὾༡ഃࠋC. すஅ὾᭱໭➃ࠋD. すஅ὾᭱༡➃ࠋE. ༡す὾᭱໭➃ࠋF. ༡す὾୰ኸ࠿ࡽ༡ഃࠋ
Fig. 2. Environments of survey sites
A. Center to northern part of Nishinohama. B. Southern part of Nishinohama. C.
Northernmost part of Nishinohama. D. Southernmost part of Nishinohama. E. Northernmost
part of Nanseihama. F. Center to southern part of Nanseihama.

− 112 −὾ࠊ෌ᗘ኱ࡁ࡞♟὾࡜࡞ࡗ࡚◁὾࡟ኚ໬ࡋࠊሙᡤ࡟ࡼࡗ࡚ࡣࡇࡢࡼ࠺࡞ኚ໬ࡀఱᗘ࠿⥆࠸࡚࠸ࡓࠋࡇࢀࡽࡢࡇ࡜࠿ࡽࠊᾐ㣗ࡸἼᾉࡢᙳ㡪࡟ࡼࡗ࡚ࠊᾏᓊ⥺ࡢ఩⨨ࡀఱᗘࡶኚࢃࡗ࡚ࡁ࡚࠸ࡿࡇ࡜ࡀ⪃࠼ࡽࢀࡿࠋ
㸱㸫㸰㸬㈅㢮 ᮏㄪᰝ࡛ࡣࠊ㈅㢮ࡣࢩ࣡࢞ࢧࠊࢡ࣐ࣟ࢝ࣛࢶ࢞࢖ Siphonaria (Mestosiphon) subatraࠊ࢜࢞ࢧ࣡ࣛࢱ࣐࢟ࣅ Echinolittorina cinereaࠊࢥ࢘ࢲ࢝ࢱ࣐࢟ࣅ Littoraria pintado ࡢ 4✀ࡀ☜ㄆࡉࢀࡓࠋࢩ࣡࢞ࢧࡣࠊすஅ὾ࡢ໭ഃ⁐ᒾ࡛ 6 ಶయ☜ㄆࡉࢀࡓ(ᅗ 3A)ࠋ࠸ࡎ
ࢀࡶ₻㛫ᖏ୰㒊㹼ୖ㒊࡟࠿ࡅ࡚⏕ᜥࡋ࡚࠸ࡓࠋ኱ࡁࡉࡣ඲࡚ࡢಶయ࡛ 3cm ⛬ᗘ࡛࠶ࡗࡓࠋᮏ✀ࡣᑠ➟ཎㅖᓥ࠿ࡽ࣐ࣜ࢔ࢼㅖᓥ࡟࠿ࡅ࡚ศᕸࡍࡿ✀࡛ࠊࡇࢀࡽࡢᆅᇦ࡛
ࡣᬑ㏻✀࡜ࡋ࡚ࡢሗ࿌ࡀከ࠸✀࡛࠶ࡿ(୰㔝ࠊ2007; బࠎᮌ࡯࠿ࠊ2018)ࠋࢡ࣐ࣟ࢝ࣛࢶ࢞࢖ࡶすஅ὾໭ഃ⁐ᒾ࡛ࡢࡳ☜ㄆࡉࢀࡓ(ᅗ 3B)ࠋᮏ✀ࡣ₻㛫ᖏୗ㒊࡟ 2 ಶయࡢࡳ☜ㄆࡉࢀࡓࠋศᕸᇦࡣᑠ➟ཎㅖᓥ࠾ࡼࡧ໭࣐ࣜ࢔ࢼㅖᓥ࡛ࠊ༡◲㯤ᓥ࠿ࡽࡢሗ࿌ࡶ
࠶ࡿ(బࠎᮌ࡯࠿ࠊ2014ࠊ2018)ࠋࢱ࣐࢟ࣅ࢞࢖⛉࡟ᒓࡍࡿ࢜࢞ࢧ࣡ࣛࢱ࣐࢟ࣅ࡜ࢥ࢘
ࢲ࢝ࢱ࣐࢟ࣅࡣすஅ὾࠾ࡼࡧ༡す὾ࡢ୧ᆅⅬ࡛Ⓨぢࡉࢀࡓࠋࡑࢀࡒࢀ₻㛫ᖏୖ㒊㹼㣕ἓᖏࡢ⁐ᒾࡢࡃࡰࡳ࡟㞃ࢀࡿࡼ࠺࡟⏕ᜥࡋ࡚࠸ࡓ(ᅗ 3C, D)ࠋ኱ࡁࡉࡣከࡃࡢಶయ
࡛ 5mm ๓ᚋ࡛࠶ࡗࡓࡀࠊ༡す὾࡛ぢࡘ࠿ࡗࡓ࢜࢞ࢧ࣡ࣛࢱ࣐࢟ࣅ 1 ಶయࡢࡳ 1cm⛬࡛࠶ࡗࡓࠋᒾࡢࡃࡰࡳ࡟࠸ࡿࡓࡵṇ☜࡞ಶయᩘࢆᩘ࠼ࡿࡇ࡜ࡀ࡛ࡁ࡞࠿ࡗࡓࡀࠊ
1m2 ෆ࡟᭱኱ 5 ಶయ⏕ᜥࡋ࡚࠸ࡓࠋ࡝ࡕࡽࡢ✀ࡶᑠ➟ཎㅖᓥ∗ᓥࡸ༡◲㯤ᓥ࡛㠀ᖖ࡟㧗ᐦᗘ࡟⏕ᜥࡋ࡚࠸ࡿࡇ࡜ࡀሗ࿌ࡉࢀ࡚࠾ࡾ(బࠎᮌ࡯࠿ࠊ2014ࠊ2018)ࠊすஅᓥ࡛ࡢศᕸᐦᗘࡣ㠀ᖖ࡟ᑠࡉ࠸࡜⪃࠼ࡽࢀࡿࠋ࢜࢞ࢧ࣡ࣛࢱ࣐࢟ࣅࡣᑠ➟ཎㅖᓥࠊࢺ࢝ࣛิᓥ௨༡ࠊ⇕ᖏኴᖹὒࠊࢥ࢘ࢲ࢝ࢱ࣐࢟ࣅࡣ⣖ఀ༙ᓥ௨༡ࠊ⇕ᖏኴᖹὒࠊ࢖ࣥࢻὒ࡜ᗈ⠊ᅖ࡟ศᕸࡋ࡚࠸ࡿᗈᇦ✀࡛࠶ࡿ(㛗㇂ᕝࠊ2017)ࠋ
㸱㸫㸱㸬⏥Ẇ㢮 ⏥Ẇ㢮ࡣ࢜࢜࢖࣡࢞ࢽ Grapsus tenuicrustatus ࡜࢜࢜࢝ࢡࣞ࢖࣡࢞ࢽ Geograpsus
crinipes ࡢ 2 ✀ࡀⓎぢࡉࢀࡓࠋ࢜࢜࢖࣡࢞ࢽࡣすஅ὾ࠊ༡す὾ࡢ୧ഃ࡟ᗈࡀࡿ⁐ᒾ௜㏆࡟ከࡃࡢಶయࡀ⏕ᜥࡋ࡚࠸ࡓ(ᅗ 3E, F)ࠋศᕸࡣࣃࢵࢳ≧࡛ࡣ࠶ࡗࡓࡶࡢࡢࠊ1m2
ෆ࡟ 20 ಶయ⛬ᗘ☜ㄆ࡛ࡁࡓሙᡤࡶ࠶ࡿࠋすஅ὾ࠊ༡す὾඲య࡛ࡣ 50 ಶయ⛬ᗘ☜ㄆ࡛ࡁࡓࠋẆᖜ 4cm㹼5cm ⛬ᗘࠊ3cm㹼4cm ⛬ᗘࠊ1cm㹼2cm ⛬ᗘࡢయࢧ࢖ࢬࡢ᫂░࡟
␗࡞ࡿ 3 㞟ᅋࡀ☜ㄆ࡛ࡁࡓࠋᮏ✀ࡣࠊἈ⦖ࠊᑠ➟ཎࠊྎ‴ࠊᮾ༡࢔ࢪ࢔࡜ᗈᇦ࡟ศ
ᕸࡋ࡚࠸ࡿࠋ࢜࢜࢝ࢡࣞ࢖࣡࢞ࢽࡣᪧᓥྎᆅ௜㏆࡛Ⓨぢࡉࢀࡓࠋᪧᓥࡣᾏᓊ⥺࠿ࡽ⣙ 200m 㞳ࢀ࡚࠾ࡾࠊ㠀ᖖ࡟஝⇱ࡋ࡚࠸ࡿሙᡤ࡛࠶ࡿࠋ᫨㛫ࡢㄪᰝ࡛ࡣ 2 ಶయⓎぢࡉࢀࡓࡢࡳ࡛࠶ࡗࡓࡀࠊ㫽㢮࡜᪻⹸ࢆᑐ㇟࡜ࡋࡓኪ㛫ㄪᰝࡢ㝿࡟ࠊᪧᓥྎᆅ࡟࡚࢜
࢜࢝ࢡࣞ࢖࣡࢞ࢽࡀࡉࡽ࡟ 2 ಶయṌ࠸࡚࠸ࡿࡢࡀ☜ㄆࡉࢀࡓ(ᅗ 3G)ࠋ− 113 −ᅗ 3㸬ㄪᰝ࡟ࡼࡾⓎぢࡉࢀࡓ✀
A. ࢩ࣡࢞ࢧࠋB. ࢡ࣐ࣟ࢝ࣛࢶ࢞࢖ࠋC. ࢜࢞ࢧ࣡ࣛࢱ࣐࢟ࣅࠋD. ࢥ࢘ࢲ࢝ࢱ࣐࢟
ࣅࠋE. ࢜࢜࢖࣡࢞ࢽࠋF. ࢜࢜࢖࣡࢞ࢽࠋG. ࢜࢜࢝ࢡࣞ࢖࣡࢞ࢽ (ᕝୖ࿴ே᧜ᙳ)ࠋ
H. ࢜࢜࢝ࢡࣞ࢖࣡࢞ࢽࡢᗂయࠋ
Fig. 3. Species occurred in the survey
A. Cellana radiata enneagona. B. Siphonaria (Mestosiphon) subatra. C. Echinolittorina
cinerea, D. Littoraria pintado, E. Grapsus tenuicrustatus, F. Grapsus tenuicrustatus, G.
Geograpsus crinipes (photographed by Kazuto Kawakami), H. Juvenile of Geograpsus
crinipes.

− 114 −ࡲࡓᪧᓥྎᆅ࡟௙᥃ࡅࡽࢀࡓ᪻⹸ᤕ⋓⏝ࡢࣂࢢࢺࣛࢵࣉ࡟ࡣẆᖜᩘ mm ࡢ࢜࢜࢝ࢡࣞ࢖࣡࢞ࢽࡢᗂయࡀᤕ⋓ࡉࢀࡓࠋࡉࡽ࡟༡す὾࡛ࡶᾏᓊ⥺࠿ࡽᩘⓒ m 㞳ࢀࡓᆅⅬࡢ▼ࡢୗ࠿ࡽࡶẆᖜᩘ mm ࡢ࢜࢜࢝ࢡࣞ࢖࣡࢞ࢽࡢᗂయࡀⓎぢࡉࢀࡓ(ᅗ 3H)ࠋ

㸱㸫㸲㸬㨶㢮 ⴭ⪅ࡽࡣ┤᥋☜ㄆ࡛ࡁ࡞࠿ࡗࡓࡀࠊㄪᰝ㝲࣓ࣥࣂ࣮ࡀ 2 ಶయࡢ࢔࢜ࣔࣥࢠ࣏ࣥ
Entomacrodus caudofasciatus ࢆすஅ὾໭➃ࡢ₻㛫ᖏ࡛☜ㄆࡋࡓ(ᅗ 4)ࠋᮏ✀ࡣࠊἼࡀ⃭ࡋࡃᡴࡕࡘࡅࡿ☾࡟⏕ᜥࡋ࡚࠾ࡾࠊඵ୔ᓥࠊᑠ➟ཎㅖᓥࠊ⌰⌫ิᓥࠊ࢖ࣥࢻ࣭ኴᖹὒ࡜ᗈᇦ࡟ศᕸࡋ࡚࠸ࡿࠋయ㛗ࡣ 6-8cm ࠶ࡾᡂ㨶࡜⪃࠼ࡽࢀࡿࠋᮏㄪᰝ࡛ࡣࠊ┠ど࡟ࡼࡿ㨶㢮ㄪᰝࡣ┠ⓗ࡜ࡋ࡞࠿ࡗࡓࡀࠊ௒ᚋࠊ⎔ቃ DNA ࢆ⏝࠸ࡓゎᯒࢆணᐃࡋ࡚࠾ࡾࠊἢᓊ㒊ࡢᾏỈࢧࣥࣉࣝࢆ᥇ྲྀࡋᣢࡕᖐࡗࡓࠋ
ᅗ 4㸬࢔࢜ࣔࣥࢠ࣏ࣥ (Ώ㑓⠜ᚿ᧜ᙳ)
Fig. 4. Entomacrodus caudofasciatus (photographed by Atsushi Watanabe)㸱㸫㸳㸬ᄇⅆࡀすஅᓥࡢᾏὒ⏕≀┦࡟୚࠼ࡓᙳ㡪
 2013 ᖺ࠿ࡽጞࡲࡗࡓᄇⅆࡢᙳ㡪ࢆㄪ࡭ࡿࡓࡵ࡟ࡣࠊᄇⅆࡀጞࡲࡿ๓ࡢすஅᓥࡢ⏕≀┦࡜ẚ㍑ࡍࡿᚲせࡀ࠶ࡿࠋᮾி㒔࡟ࡼࡿᄇⅆ๓ࡢ 2012 ᖺࡢㄪᰝ࡛ࡣࠊ㈅㢮࡜ࡋ࡚࢖࣎ࢱ࣐࢟ࣅ 1 ಶయࠊࢥ࢘ࢲ࢝ࢱ࣐࢟ࣅ 6 ಶయࠊ࣓ࣚ࢞࢝ࢧ 1 ಶయࠊ⏥Ẇ㢮࡜ࡋ࡚࣑ࢼ࣑࢔࢝࢖ࢯ࢞ࢽ 1 ಶయࠊ࢜࢜࢖࣡࢞ࢽ 10 ಶయࡀሗ࿌ࡉࢀ࡚࠸ࡿ(ᮾி㒔ᑠ➟ཎᨭᗇᅵᮌㄢ⮬↛බᅬಀࠊ2013)ࠋᮏሗ࿌࡟࠶ࡿ࣓ࣚ࢞࢝ࢧࡣᑠ➟ཎㅖᓥ࡟ࡣ
ศᕸࡋ࡞࠸✀࡛࠶ࡿࡢ࡛ࠊ࠾ࡑࡽࡃࢩ࣡࢞ࢧࡢ㛫㐪࠸࡛࠶ࡿࠋ࢖࣎ࢱ࣐࢟ࣅ࡜ࢥ࢘ࢲ࢝ࢱ࣐࢟ࣅࡢಶయᩘࡀ㠀ᖖ࡟ᑡ࡞࠸ࡀࠊྥ ဴႹẶ㸦ᮾி㒔ᑠ➟ཎᨭᗇ㸧࡟ࡼࡿㄪᰝ࡛ࡣࠊ࢜࢞ࢧ࣡ࣛࢱ࣐࢟ࣅࡸࢥ࢘ࢲ࢝ࢱ࣐࢟ࣅࡀ㧗ᐦᗘ࡛ศᕸࡋ࡚࠾ࡾࠊࡇࢀࡽࡢ✀㢮࡟ຍ࠼࡚࢖࣎ࢱ࣐࢟ࣅࡀከᩘ⏕ᜥࡋ࡚࠸ࡿࡇ࡜ࡀุ᫂ࡋ࡚࠸ࡿ(ྥࠊ− 115 −ᮍⓎ⾲)ࠋࡲࡓࢩ࣡࢞ࢧࡢṚẆࡀⴠࡕ࡚࠸ࡿᵝᏊࡶ☜ㄆ࡛ࡁࠊᄇⅆ๓ࡢすஅᓥ࡟ࡣᑡ࡞ࡃ࡜ࡶ࢖࣎ࢱ࣐࢟ࣅࠊࢥ࢘ࢲ࢝ࢱ࣐࢟ࣅࠊ࢖࣎ࢱ࣐࢟ࣅࠊࢩ࣡࢞ࢧࡣᬑ㏻✀
࡜ࡋ࡚ศᕸࡋ࡚࠸ࡓ࡜⪃࠼ࡽࢀࡿࠋࡲࡓ࢜࢜࢖࣡࢞ࢽ࡟ࡘ࠸࡚ࡶᄇⅆ๓ࡢ࡝ࡕࡽ
ࡢㄪᰝ࡛ࡶグ㘓ࡉࢀ࡚࠾ࡾࠊᄇⅆ๓ࡢすஅᓥ࡟࠾࠸࡚ᬑ㏻✀࡛࠶ࡗࡓ࡜⪃࠼ࡽࢀࡿࠋ ᄇⅆ๓࡜ᄇⅆᚋࡢすஅᓥ࡛ඹ㏻ࡍࡿ✀ࡣࠊ࢜࢞ࢧ࣡ࣛࢱ࣐࢟ࣅࠊࢥ࢘ࢲ࢝ࢱ࣐࢟ࣅࠊࢩ࣡࢞ࢧࠊ࢜࢜࢖࣡࢞ࢽ࡛࠶ࡿࠋࡋ࠿ࡋ࡞ࡀࡽࠊ⌧ᅾࡢすஅᓥ࡟ศᕸࡋ࡚࠸ࡿ✀ࡣ࢜࢜࢖࣡࢞ࢽࢆ㝖࠸࡚㠀ᖖ࡟ಶయᩘࡀᑡ࡞ࡃࠊᄇⅆࡢᙳ㡪ࡣ኱ࡁ࠿ࡗࡓࡶࡢ࡜ᛮࢃࢀࡿࠋࡲࡓᄇฟࡋࡓ⁐ᒾ࡟ࡼࡗ࡚ᾏᓊ⥺඲࡚ࡀ᪂ࡋ࠸⁐ᒾࡢྎᆅ࡟⨨ࡁ᥮ࢃࡗࡓࡇ࡜࡟ࡼࡾࠊ⏕ᜥሙᡤࢆኻࡗࡓ₻㛫ᖏ⏕≀ࡣ୍ᗘ඲࡚⤯⁛ࡋࡓࡶࡢ࡜
⪃࠼ࡽࢀࡿࠋᮏㄪᰝ࡛ࡣ࢜࢜࢖࣡࢞ࢽࡣẚ㍑ⓗಶయᩘࡀከ࠿ࡗࡓࡀࠊᮏ✀ࡣ࠾ࡑࡽࡃ୍ᗘすஅᓥ࡛⤯⁛ࡋࡓᚋࠊ෌ᗘすஅᓥ࡟࠸ࡕ᪩ࡃᡠࡗ࡚ࡁࡓࡶࡢ࡜⪃࠼ࡽࢀࡿࠋ
ᅗ 5㸬ᪧᓥྎᆅୖ࡟ᩓࡽࡤࡿ㫽ࡢ㣵
A. ࢖࢝㢮ࠋB. ࢺࣅ࢘࢜ࠋFig. 5. Bird feeding on the remnant of the old Island
A. Squids. B. A dried flying fish.
㸱㸫㸴㸬ᾏὒᓥ࡬ࡢ㐍ฟ すஅᓥࡣࠊᮏᕞ࠿ࡽ༡࡟⣙ 1,000kmࠊἈ⦖࠿ࡽᮾ࡬⣙ 1,300km ࡟఩⨨ࡋࠊ᭱ࡶ㏆࠸∗ᓥ࠿ࡽࡶ 130km 㞳ࢀ࡚࠸ࡿࠋ㐲ࡃ㞳ࢀࡓᾏὒᓥ࡬ࡢᾏὒ⏕≀ࡢศᩓ᪉ἲ࡜ࡋ࡚
ࡣࠊᾋ㐟ᗂ⏕᫬ࡢᾏὶศᩓࠊᾏⲡࡸὶᮌ࡟஌ࡗ࡚ࡢࣛࣇࢸ࢕ࣥࢢࠊ᪂ࡋ࠸ᓥࡢฟ⌧࡞࡝࡟ࡼࡿࢫࢸࢵࣆࣥࢢࢫࢺ࣮ࣥࡀᣲࡆࡽࢀࡿࠋᮏㄪᰝ࡛ࡣࠊᡴࡕୖࡆࡽࢀࡓᾏⲡ
ࡸὶᮌ࡞࡝ࡣぢࡽࢀࡎࠊ୍㒊࢚࣎ࢩ࢞࢖ࡀ௜╔ࡋࡓ࣌ࢵࢺ࣎ࢺࣝࡀぢࡽࢀࡓࡢࡳ࡛࠶ࡗࡓࠋᓥෆ࡟࠶ࡕࡇࡕࣉࣛࢫࢳࢵࢡ〇ရࡀⴠࡕ࡚࠸ࡓࡀࠊࡑࢀࡽࡣ㫽ࡀᕢᮦ࡜ࡋ࡚ᾏὒ࡟ᾋ࠸࡚࠸ࡿࡶࡢࢆ㞟ࡵ࡚ࡁ࡚ᕢ࡜ࡋ࡚౑⏝ࡋ࡚࠸ࡿࡶࡢ࡛࠶ࡗࡓ(ᕝୖ࣭ᑠ− 116 −ᒣ⏣ࠊ2020)ࠋࡑࡢࡓࡵ⌧ẁ㝵࡛ࡣࠊࣛࣇࢸ࢕ࣥࢢ࡟ࡼࡿすஅᓥ࡬ࡢᾏὒ⏕≀ࡢ⁻╔ࡣ࠶ࡲࡾ⪃࠼ࡽࢀ࡞࠸ࠋ᪂ࡓ࡞ᓥࡢฟ⌧ࡸ႙ኻ࡟క࠺ࢫࢸࢵࣆࣥࢢࢫࢺ࣮ࣥࡣᆅ㉁Ꮫⓗ࡞᫬㛫ࡀᚲせ࡛࠶ࡾࠊ⌧ᅾࡢすஅᓥ࡬ࡢᾏὒ⏕≀ࡢ㐍ฟࡣᾋ㐟ᗂ⏕᫬ࡢᾏὶศᩓࡀ୺࡛࠶ࡿ࡜⪃࠼ࡽࢀࡿࠋ ✀࡟ࡼࡗ࡚ᾋ㐟ᗂ⏕ᮇࡣ␗࡞ࡾࠊ௒ᅇ☜ㄆ࡛ࡁࡓ✀ࡢ࠺ࡕࠊࢱ࣐࢟ࣅ㢮࡜⏥Ẇ㢮ࡣᾋ㐟ᗂ⏕ᮇࡀ 3㹼4 㐌⛬ᗘ࡜㛗ࡃࠊẚ㍑ⓗᐜ᫆࡟㐲ࡃࡲ࡛ศᩓࡀྍ⬟࡛࠶ࡿࠋࡉࡽ࡟ࢱ࣐࢟ࣅ㢮ࡣ₻㛫ᖏୖ㒊࠿ࡽ㣕ἓᖏ࡟⏕ᜥࡋ᭱ࡶ஝⇱࡟ᙉ࠸ᕳ㈅㢮ࡢࢢ࣮ࣝࣉ࡛࠶ࡿࠋ㣗ᛶࡣ⸴㣗ᛶ࡛࠶ࡾࠊ㣕ἓᖏ࡜࠸࠺࠶ࡲࡾ⸴㢮ࡢ㇏ᐩ࡛࡞࠸࡜ࡇࢁ࡛ࡶ⏕ࡁ࡚࠸ࡅࡿ஦࠿ࡽࠊࡇࡢࡼ࠺࡞᪂ࡋࡃฟ⌧ࡋࡓⅆᒣᓥ࡬ࡢ᪩ᮇࡢ㐍ฟ࡟㐺ࡋ࡚࠸ࡿ࡜ᛮࢃࢀࡿࠋ⏥Ẇ㢮ࡢ࠺ࡕࠊ࢜࢜࢖࣡࢞ࢽࡣẚ㍑ⓗከࡃࡢಶయᩘࡀ☜ㄆ࡛ࡁࡓࠋᮏ
✀ࡣ㞧㣗࡛ᮏㄪᰝ୰࡟ᒾࡢ⾲㠃ࢆࡘࡘ࠸࡚㣵ࢆྲྀࡗ࡚࠸ࡿᵝᏊࡀ☜ㄆ࡛ࡁࡓࠋ࢜࢜࢖࣡࢞ࢽࡣἼᙜࡓࡾࡢᙉ࠸ᾏᓊ⥺࡟ከࡃศᕸࡋ࡚࠸ࡿࡇ࡜࠿ࡽࠊすஅᓥࡢ⎔ቃ࡟ࡶࡗ࡜ࡶ㐺ᛂࡋ࡚࠸ࡿ✀࡜ゝ࠼ࡿࠋయࢧ࢖ࢬࡢ᫂░࡟␗࡞ࡿ 3 㞟ᅋࡀ࠾ࡾࠊ࠾ࡑࡽࡃ
ᓥෆ࡛ࡢ෌⏕⏘ࡶ⾜ࢃࢀ࡚࠸ࡿ࡜⪃࠼ࡽࢀࠊࡍ࡛࡟すஅᓥ࡟ᐃ╔ࡋࡓ࡜⪃࠼ࡽࢀࡿࡔࢁ࠺ࠋ࢜࢜࢝ࢡࣞ࢖࣡࢞ࢽࡣᤕ㣗⪅࡛࠶ࡿࡀࠊ⋓≀࡜࡞ࡿࡼ࠺࡞⏕≀ࡣᪧᓥྎᆅୖ࡟ࡣ࠸࡞࠿ࡗࡓࠋࡋ࠿ࡋ࡞ࡀࡽࠊᪧᓥྎᆅ࡛ࡣ࢔࢜ࢶࣛ࢝ࢶ࢜ࢻࣜࡸ࢜ࢼ࣑࢞ࢬࢼࢠࢻࣜ࡞࡝ࡀႠᕢࡋ࡚࠾ࡾࠊぶ㫽ࡀ㞮࡟୚࠼ࡿࡓࡵ࡟㐠ࢇ࡛ࡁࡓ࢖࢝㢮ࡸࢺࣅ࢘࢜࡞࡝ࡀ࠶ࡕࡇࡕ࡟ᩓ஘ࡋ࡚࠸ࡿᵝᏊࡀ☜ㄆ࡛ࡁࡓ(ᅗ 5A, B)ࠋ࠾ࡑࡽࡃࡇࢀࡽࢆ㣵࡜ࡋ⏕Ꮡࡋ࡚࠸ࡿࡶࡢ࡜⪃࠼ࡽࢀࡿࠋࡲࡓᪧᓥྎᆅୖࡸᾏᓊ⥺࠿ࡽᩘⓒ m 㞳ࢀࡓ㌿▼ୗ࡟ࡶ࢜࢜࢝ࢡࣞ࢖࣡࢞ࢽࡢᗂయࡀ☜ㄆࡉࢀ࡚࠾ࡾࠊ㧗࠸஝⇱⪏ᛶࡀすஅᓥ࡬ࡢ᪩ᮇ㐍ฟࢆྍ⬟࡟ࡋࡓ࡜ᛮࢃࢀࡿࠋ ࢩ࣡࢞ࢧࠊࢡ࣐ࣟ࢝ࣛࢶ࢞࢖ࡣᾋ㐟ᗂ⏕ᮇࡀ▷࠸ࢢ࣮ࣝࣉ࡛࠶ࡾࠊᮏㄪᰝ࡛Ⓨぢࡉࢀࡓࡇ࡜ࡣ㠀ᖖ࡟⯆࿡῝࠸ࠋ≉࡟࢝ࢧ࢞࢖㢮ࡢᾋ㐟ᗂ⏕ᮇࡣ 2,3 ᪥⛬ᗘ࡜㠀ᖖ࡟▷ࡃ(Nakano et al., 2020)ࠊศᏊ⣔⤫Ꮫⓗ࡞࢔ࣉ࣮ࣟࢳ࠿ࡽᾋ㐟ᗂ⏕᫬࡟ศᩓྍ⬟࡞㊥㞳ࡣ 100-200km ⛬ᗘ࡜ぢ✚ࡶࡽࢀ࡚࠸ࡿ(Nakano & Sasaki, 2011)ࠋすஅᓥ࿘㎶ࡢᾏὶࡣࡲࡔࡼࡃศ࠿ࡗ࡚࠸࡞࠸ࡀࠊ᭱ࡶ㏆࠸∗ᓥ࠿ࡽᗂ⏕ࡀ㐠ࡤࢀࡓ࡜ࡋ࡚ࡶ 130km
ࡢ㊥㞳ࢆΏࡽ࡞ࡅࢀࡤ࡞ࡽࡎࠊᾏὶ௵ࡏ࡛㐠ࡤࢀすஅᓥ࡟㐍ฟࡍࡿࡇ࡜ࡣወ㊧࡟㏆࠸ࡔࢁ࠺ࠋ௒ᅇⓎぢࡉࢀࡓࢩ࣡࢞ࢧࡣ 3cm ⛬ᗘ࡛࠶ࡗࡓࠋᑠᆺࡢ࢝ࢧ࢞࢖㢮࡛ࡣ 1ᖺ࡛ 1cm ⛬ᗘᡂ㛗ࡋ(Nakayama et al., unpublished)ࠊ኱ᆺࡢ✀࡛ࡣ 1 ᖺ࡛ 1.5cm㹼2cm⛬ᗘᡂ㛗ࡍࡿ஦ࡀ▱ࡽࢀ࡚࠸ࡿ(⡿ᒣ࡯࠿ࠊ2007)ࠋᮏㄪᰝ࡛ぢࡘ࠿ࡗࡓࢩ࣡࢞ࢧࡣ
࠾ࡑࡽࡃ╔ᗏࡋ࡚࠿ࡽ 2 ᖺ㹼3 ᖺ⛬ᗘ⤒㐣ࡋ࡚࠸ࡿ࡜⪃࠼ࡽࢀࡿࠋࡲࡓ⏕ᜥࡋ࡚࠸ࡓ⁐ᒾࡀ 2015 ᖺࡢᄇⅆ࡛ᄇฟࡋࡓ⁐ᒾ࡛࠶ࡿࡓࡵࠊ2019 ᖺࡢㄪᰝ࡛ࢩ࣡࢞ࢧࡀぢࡘ࠿ࡗ࡚࠸ࡿ஦࠿ࡽ㏫⟬ࡍࡿ࡜ 2016 ᖺ࠿ 2017 ᖺ࡟ࡣᐃ╔ࡋ࡚ࡁࡓ࡜⪃࠼ࡽࢀࡿࠋࡘࡲࡾ⁐ᒾࡀᄇฟࡋ࡚ࠊ1,2 ᖺᚋ࡟ࡣຍධࡋ࡚ࡁࡓィ⟬࡛࠶ࡿࠋ ᾋ㐟ᗂ⏕ᮇࡢ㛗࠸✀ࠊ࢜࢞ࢧ࣡ࣛࢱ࣐࢟ࣅࠊࢥ࢘ࢲ࢝ࢱ࣐࢟ࣅࠊ࢜࢜࢖࣡࢞ࢽࠊ࢜࢜࢝ࢡࣞ࢖࣡࢞ࢽࡣ⇕ᖏኴᖹὒ࡟ᖜᗈࡃศᕸࡍࡿᗈᇦ✀࡛࠶ࡾࠊṇ☜࡟࡝ࡇ࠿ࡽ

− 117 −ᗂ⏕ࡀὶࢀ╔࠸࡚ࡁࡓ࠿᥎ᐃࡍࡿ࡟ࡣࠊᵝࠎ࡞ᆅᇦ࠿ࡽࢧࣥࣉࣝࢆ᥇㞟ࡋ DNA ࢆ⏝࠸ࡓศᏊ⣔⤫ゎᯒࡀᚲせ࡛࠶ࡿࠋࡋ࠿ࡋ࡞ࡀࡽࠊᾋ㐟ᗂ⏕ᮇࡀ▷࠸ࢩ࣡࢞ࢧ࡜ࢡ
࣐ࣟ࢝ࣛࢶ࢞࢖ࡣᑠ➟ཎㅖᓥ࿘㎶࡟ࡢࡳศᕸࡍࡿ✀࡛࠶ࡿ஦࠿ࡽࠊ∗ᓥ࡞࡝࠿ࡽᗂ⏕ࡀὶࢀ╔࠸࡚࠸ࡿྍ⬟ᛶࡀ㧗࠸ࠋ ᾋ㐟ᗂ⏕ᮇࡀ㛗ࡃᑠ➟ཎㅖᓥ࿘㎶࡛ࡶᬑ㏻࡟ぢࡽࢀࡿࡼ࠺࡞࢘ࢽ㢮ࡸࣇࢪࢶ࣎㢮ࡀ୍ษⓎぢࡉࢀ࡞࠿ࡗࡓࡇ࡜ࡶ㠀ᖖ࡟⯆࿡῝࠸ࠋ㸱㸫㸵㸬すஅᓥࡢᏛ⾡ⓗ౯್࡜௒ᚋࡢࣔࢽࢱࣜࣥࢢ ᾏὒᓥ࡬ࡢ⏕≀ࡢ㐍ฟࡣࠊ࿘㎶ᆅᇦࡢ⏕≀┦ࡢẚ㍑ࡸศᏊ⣔⤫Ꮫⓗ࢔ࣉ࣮ࣟࢳ࠿
ࡽࡢ᥎ᐹࡀ୺࡛࠶ࡗࡓࡀࠊᄇⅆ࡟క࠸᪂ᓥࢆᙧᡂࡋࡓすஅᓥࡣᐇ㝿࡟⏕≀ࡢ㑄⛣ࢆ┤᥋ほᐹࡍࡿᶵ఍ࢆᚓࡽࢀࡿ㠀ᖖ࡟㈗㔜࡞ᓥ࡛࠶ࡿࠋ≉࡟ᮏㄪᰝ࡛ࡣࠊᄇⅆ࡟క࠸₻㛫ᖏᾏὒ⏕≀┦ࡣ୍ᗘ⤯⁛ࡋࡓ࡛࠶ࢁ࠺࡜࠸࠺஦ࠊᑡ࡞࠸࡞ࡀࡽࡶ㈅㢮 4 ✀ࠊ⏥Ẇ㢮 2 ✀ࠊ㨶㢮 1 ✀ࡢ㑄⛣ࡀ☜ㄆࡉࢀࠊ௒ࡲࡉ࡟㑄⛣ࡀጞࡲࡗࡓ࡜࠸࠺஦ࡀグ㘓࡛ࡁࡓ஦࠿ࡽࠊすஅᓥࡢᏛ⾡ⓗ౯್ࡀ㠀ᖖ࡟㧗࠸ࡇ࡜ࡀศ࠿ࡗࡓࠋ௒ᚋࡣࡉࡽ࡞ࡿ㑄⛣ࡀ࡝ࡢࡼ࠺࡟㐍ࡴ࠿ࠊࣔࢽࢱࣜࣥࢢㄪᰝࡀ⥆ࡅࡽࢀࡿࡇ࡜ࢆᕼᮃࡍࡿࠋࡲࡓேⅭⓗ࡞ᙳ㡪ࡀ࡞࠸ࡼ࠺↓⏝࡞ୖ㝣➼ࡀ↓࠸ࡼ࠺࡟ษ࡟ᮃࡴࠋ ᮏㄪᰝ࡛ࡣእ᮶✀ࡢᣢ㎸ࡳ࡞࡝ேⅭⓗ࡞ᙳ㡪ࡀฟ࡞࠸ࡼ࠺࡟ᵝࠎ࡞ᑐ⟇ࡀྲྀࡽࢀࡓࡀ(᳃࡯࠿ࠊ2020)ࠊ௒ᚋࡢㄪᰝ࡟࠾࠸࡚ࡶྠᵝ࡟⣽ᚰࡢὀពࢆᡶ࠺ᚲせࡀ࠶ࡿࠋୖ㝣ᅇᩘࢆῶࡽࡍ࡟ࡣࠊᾏỈ୰ࡢ⎔ቃ DNA ࡟ࡼࡿゎᯒࡀᮃࡲࡋ࠸࡛࠶ࢁ࠺ࠋࡋ࠿ࡋ࡞ࡀࡽࠊ㨶㢮࡜࢝ࢽ㢮࡟࠾࠸࡚ࡣゎᯒ⏝ࡢࣉࣛ࢖࣐࣮ࡀ㛤Ⓨࡉࢀ࡚࠸ࡿࡀ(Miya etal., 2015; Komai et al., 2019)ࠊ㈅㢮ࠊ࢘ࢽ㢮ࠊࣇࢪࢶ࣎㢮࡟࠾࠸࡚ࡣࡲࡔᮍ㛤Ⓨ࡛࠶ࡿࠋࡲࡓ㑄⛣ࡢึᮇẁ㝵࡛࠶ࡿࡓࡵࠊᩘಶయࡋ࠿࠸࡞࠸✀࡟࠾࠸࡚ࡣ☜ᐇ࡟᳨ฟ࡛ࡁࡿ࡜ࡣゝ࠸㞴࠸ࠋ௒ᚋ᪂ࡓ࡞ᢏ⾡ࡢ㛤Ⓨ࡜࡜ࡶ࡟ࠊ⎔ቃ DNA ゎᯒ⏝ࡢᐃᮇⓗ࡞ᾏỈࢧࣥࣉࣜࣥࢢ࡜ྜࢃࡏࠊ᭱ప㝈ࡢୖ㝣࡟ࡼࡿ┠どㄪᰝࢆ⥅⥆ࡋ࡚࠸ࡃᚲせࡀ࠶ࡿࡔࢁ࠺ࠋ㸲㸬ㅰ㎡
 ᮏㄪᰝࡣࠊ⎔ቃ┬࡟ࡼࡿ௧࿴ඖᖺᗘすஅᓥ⥲ྜᏛ⾡ㄪᰝ࡜ࡋ࡚⾜ࢃࢀࡓࠋすஅᓥㄪᰝ㝲ࡢ඲㝲ဨ࠾ࡼࡧ㝲ࡢࢧ࣏࣮ࢺࢆ㡬࠸ࡓ㛵ಀ⪅ࠊᐙ᪘࡟ཌࡃᚚ♩⏦ࡋୖࡆࡿࠋ㨶㢮ࡢྠᐃࡣࠊி㒔኱Ꮫ⥲ྜ༤≀㤋ࡢబ⸨ᓫ༤ኈ࡟ࡈຓゝ㡬࠸ࡓࠋ
㸳㸬ᘬ⏝ᩥ⊩
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OGASAWARA RESEARCHSUMMARY

Marine organisms in the intertidal zone of Nishinoshima IslandTomoyuki NAKANO1 & Ryuichi MINATO2
1. Seto Marine Biological Laboratory, Field Science and Education Center, Kyoto
University, 459 Shirahama, Nishimuro, Wakayama 649-2211, Japan.
2. Japan Wildlife Research Center, 3-3-7 Kotobashi, Sumida, Tokyo 130-8606, Japan.
*nakano.tomoyuki.2a@kyoto-u.ac.jp
We investigated marine organisms in the intertidal zone of Nishinoshima Island inSeptember, 2019. During this survey, four species of molluscs, Cellana radiata enneagona,Siphonaria (Mestosiphon) subatra, Echinolittorina cinerea, Littoraria pintado, two speciesof crustacean, Grapsus tenuicrustatus, Geograpsus crinipes and one fish species
Entomacrodus caudofasciatus were recorded. Cellana radiata enneagona, Siphonaria(Mestosiphon) subatra are endemic to Ogasawara Islands and adjacent areas, but the others
have wide geographic distribution in tropical Pacific. The intertidal marine organisms may
extinct due to the volcanic eruption since only a small number of individuals were found ineach species except for Grapsus tenuicrustatus. Subsequently, marine organisms may newly
colonize to Nishinoshima Island by larval dispersal.
 Key words
 Colonization, Crustacean, Dispersal, Mollusca, Ogasawara Islands− 121 −