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Annual sea-surface temperatures recorded from a coral habitat off the coast ofMinami-Iwo-To IslandTetsuro SASAKI1*, Tetsuya YAMADA2, Akitsugu MUKAI1,Sora HORIKOSHI1, Yosuke AMEDA1 & Takumi SEKIGUCHI2
1. ̲ǈҸŻĞ˹ı˵Ë ǞΏŌϠ̩ɺĸͨΆɃӞ100-2101 ʪÊҀǞΏŌʦ̮ǮƽИ͋ӟ
Institute of Boninology, Nishimachi, Chichijima, Ogasawara, Tokyo 100-2101, Japan.
2. w]¥hm¨q KAIZINӞ100-2101 ʪÊҀǞΏŌʦ̮ǮƽƱʦӟ
Diving Service KAIZIN, Okumura, Chichijima, Ogasawara, Tokyo 100-2101, Japan.
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΀ϺȽ§ƖэŰƬ Ӟ2003ӟ ǞΏŌзǮ<#Tm¥lƩМˌ͕ĸӞѪƘӟ. ǞΏŌͨΆȅƘ, 27: 17-30.
Islands care Ӟ2017ӟ Ȅȿ 28 ȅȍ ¥¤¨c¨Á˅ǞΏŌƈΊĊƉ˟ǮĚǮŬѝ̀Ɠ<#T˥̎У̏˅ĲƘūʗ, ͂Ɯ͝Ҙʪƌɿ͂ƜÁĲɃ.
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ǞΏŌϠ̩ɺĸͨΆɃ Ӟ2016ӟ Ȅȿ 27 ȅȍ ¥¤¨c¨Á˅ǞΏŌƈΊĊƉ?̀Ɠ<#T˥̎У̏˅ĲƘūʗ, ͂Ɯ͝Ҙʪƌɿ͂ƜÁĲɃ.
ǞΏŌϠ̩ɺĸͨΆɃ Ӟ2017ӟ Ȅȿ 28 ȅȍ ¥¤¨c¨Á˅ǞΏŌƈΊĊƉ̮ǮĚǮŬѝ̀Ɠ<#T˥̎У̏˅ĲƘūʗ, ͂Ɯ͝Ҙʪƌɿ͂ƜÁĲɃ.
àʟŲʛ Ӟ2010ӟ Ǟ';όƓʹЭ?ά̧-2009 ȅǞΏŌ?m¥l?ƩМˌ͕ĸ-. ʃʢm¥lͬǂØ¨q¢v¨, 45: 4.
àʟŲʛ§ƖэŰƬ Ӟ2008ӟ ńͪӚǮ?̀˸̱̈́. ńͪӚǮϠ̩͂ƜжʴƘūʗ, ʪÊҀ§ӐҀƩǂʪÊӞκӟʪÊҀ͂ƜǢ, pp. 180-197.
ΝǩΦƬ§Ƶǡ˽ƫʛ§ǩʢцѳ Ӟ2008ӟ ǞΏŌτǮ˟Ǯ<7 2003 ȅ<͓̈́)1ѫͬm¥l?͕ĸ. ʪÊҀ˥̀ͅ˸ͨΆƘū, 2: 81-93.

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SUMMARY

Annual sea-surface temperatures recorded from a coral habitat off the coast ofMinami-Iwo-To Island
Tetsuro SASAKI1*, Tetsuya YAMADA2, Akitsugu MUKAI1,Sora HORIKOSHI1, Yosuke AMEDA1 & Takumi SEKIGUCHI2
1. Institute of Boninology, Nishimachi, Chichijima, Ogasawara, Tokyo 100-2101, Japan.
2. Diving Service KAIZIN, Okumura, Chichijima, Ogasawara, Tokyo 100-2101, Japan.
* t-sasaki@ogasawara.or.jp (author for correspondence)
From June 2016 to June 2017, we used a logger to monitor sea-surface temperatures of a coral
habitat off the coast of Minami-Iwo-To Island. During the summer, the maximum average watertemperatures around Minami-Iwo-To were 3.3°C higher than those of the Ogasawara Island Group inthe northern part of the Ogasawara Archipelago. In 2016, the water temperature in the Ogasawara Island
Group peaked between August and October, while the highest water temperatures near Minami-Iwo-To
Island were observed in July, showing that the sea-surface temperatures of Minami-Iwo-To Island tend
to differ from those of the Ogasawara Island Group.
Key words
Climatic variation, Coral bleaching, Kazan Island Group, Ogasawara Islands, Zooxanthellatescleractinian corals.

− 335 − 

500mƆ 1. ˥̎£d¨Шςƌ̥Figure 1. Location map of water temperature logger installation pointӞ ӟ.

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ABCDEFƆ 2. ńͪӚǮńǭ˭<Шς)1˥̎£d¨
A: ˥³]F?˥̎£d¨?Ƈǈã˅; B: ˥³]?̀³F?Шςã˅; C: Шςȡ?˥̎
£d¨; D: £d¨ƁŔʑ?˥̎£d¨; E§F: Ŭѝ?]om¥lτҫʒП.
Figure 2. Water temperature logger installed off Minami-Iwo-To Island.
A: Fixing work of the water temperature logger to the underwater buoy.
B: Installation of the underwater buoy on the seafloor.
C: The Underwater buoy with the logger after installation.
D: The Underwater buoy with the logger just before collection.
E§F: Coral community around the point of the logger installed.

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ABC

DEFƆ 3. ˥̎£d¨Шςƌ̥Ŭѝ?]om¥lӇ
A: go w ]o; B:  ]oǧ?ʠŢǈͿ Acropora sp.; C: bbmnm¥l
Scapophyllia cylindrica; D: oeg]o Goniastrea stelligera; E: [nm¥l Galaxea
fascicularis; F:  ]oӇ<KRU1ӓʺ͐ȁӞϝ͒ӟ.
Figure 3. Coral species occurred around the point of the water temperature logger installed.
A: Acropora hyacinthus; B: Acropora sp.; C: Scapophyllia cylindrica; D: Goniastrea stelligera; E:Galaxea fascicularis; F: Acropora sp. (growth anomalies)− 338 −Ɔ 4. ńͪӚǮńǭ?ˠʑ˥̎hӞ2016 ȅ 6 ʙ 30 ʃ2017 ȅ 6 ʙ 14 ʃӟFigure 4. Hourly sea surface temperature chart off the coast of Minami-Iwo-To Island. (From June, 30,
2016 to June, 14, 2017)Ќ 1. ǞΏŌτǮQCńͪӚǮ˲ǭ<#TʙȄƍ˥̎?ˡі
Table 1. Comparison of monthly average sea surface temperature in the Ogasawara Island group andMinami-Iwo-To Island.
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Figure 5. Monthly average sea surface temperature in the Ogasawara Island group and Minami-Iwo-To
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− 340 −