Super-fine temporal resolution past climate reconstruction from micro analysis of giant clam shell

• Project/Area Number: 25870147
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Stratigraphy/Paleontology; Geochemistry/Cosmochemistry
• Research Institution: The University of Tokyo
• Principal Investigator: SHIRAI Kotaro 東京大学, 大気海洋研究所, 助教 (70463908)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Project Status: Completed (Fiscal Year 2014)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2014: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2013: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
• Keywords: シャコガイ / 極端現象 / 古環境復元 / Sr/Ca比 / 古環境指標 / 成長線解析 / 微小領域分析 / 台風 / 化石 / 微量元素 / 安定同位体

Outline of Final Research Achievements

For the understanding and future prediction of extreme events, establishing a new method to reconstruct past-environment at diurnal scale is required. Giant clam holds great advantages for this purpose, namely the shell forms daily growth line which enable to identify a time axis at hourly scale, and holds continuous and long term environmental records up to few hundreds years. The aim of this study is to examine the giant clam shell as very high resolution past environmental proxy. Incremental width of daily growth line in fossil shell from Holocene climatic optimum showed clear seasonal fluctuation, wide in summer while narrow in winter. The low-resolution profile of the shell Sr/Ca and Mg/Ca ratio showed seasonal fluctuation along a growth direction. The 2-micrometer resolution profile of Sr/Ca ratio in the fossil shell showed clear diurnal fluctuation, indicating daily insolation cycles.

Research Products

• [Journal Article] Middle Holocene daily light cycle reconstructed from the strontium/calcium ratios of a fossil giant clam shell. (2015)
  • Author(s): M. Hori, Y. Sano, A. Ishida, N. Takahata, K. Shirai, T. Watanabe
  • Journal Title: Scientific Reports Volume: 5 Issue: 1 Pages: 1-5
  • DOI: 10.1038/srep08734
  • NAID: 120005602517
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Ion microprobe U-Pb dating and Sr isotope measurement of a protoconodont. (2014)
  • Author(s): Y. Sano, K. Toyoshima, A. Ishida, K. Shirai, N. Takahata, T. Sato, T. Komiya
  • Journal Title: Journal of Asian Earth Sciences Volume: 92 Pages: 10-17
  • DOI: 10.1016/j.jseaes.2014.05.024
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Lead concentration and isotopic composition in the Pacific sclerosponge (Acanthochaetetes wellsi) reflects environmental lead pollution. (2014)
  • Author(s): Kazuto Ohmori, Tsuyoshi Watanabe, Masaharu Tanimizu, Kotaro Shirai
  • Journal Title: Geology Volume: 42 Issue: 4 Pages: 287-290
  • DOI: 10.1130/g34316.1
  • NAID: 120005553661
  • Peer Reviewed / Open Access
• [Journal Article] Assessment of the mechanism of elemental incorporation into bivalve shells (Arctica islandica) based on elemental distribution at the microstructural scale (2014)
  • Author(s): Shirai, K., Schöne, B.R., Miyaji, T., Radarmacher, P., Krause Jr., R.A. and Tanabe, K.
  • Journal Title: Geochimica et Cosmochimica Acta Volume: 126 Pages: 307-320
  • DOI: 10.1016/j.gca.2013.10.050
  • Peer Reviewed / Open Access
• [Journal Article] 微小領域分析法を用いた生物起源炭酸塩骨格の微量元素変動メカニズムに関する研究（2013年度日本地球化学会奨励賞受賞記念論文） (2014)
  • Author(s): 白井厚太朗
  • Journal Title: 地球化学 Volume: 48 Pages: 147-167
  • Peer Reviewed
• [Journal Article] Otolith elemental and Sr isotopic composition as a natal tag for Biwa salmon Oncorhynchus masou subsp. in Lake Biwa, Japan (2013)
  • Author(s): Amano Yosuke, Kuwahara Masayuki, Takahashi Tosiro, Shirai Kotaro, Yamane Kodai, Amakawa Hiroshi, Otake Tsuguo
  • Journal Title: Aquatic Biology Volume: 19 Issue: 1 Pages: 85-95
  • DOI: 10.3354/ab00520
  • Peer Reviewed
• [Journal Article] Disturbance of shallow marine soft-bottom environments and megabenthos assemblages by a huge tsunami induced by the 2011 M9.0 Tohoku-Oki earthquake. (2013)
  • Author(s): Koji Seike, Kotaro Shirai, Yukihisa Kogure
  • Journal Title: PLOS ONE Volume: 8 Issue: 6 Pages: e65417-e65417
  • DOI: 10.1371/journal.pone.0065417
  • Peer Reviewed
• [Journal Article] Otolith δ18O of Pacific bluefin tuna Thunnus orientalis as an indicator of ambient water temperature. (2013)
  • Author(s): Kitagawa, T., T. Ishimura, R. Uozato, K. Shirai, Y. Amano, A. Shinoda, T. Otake, U. Tsunogai, and S. Kimura
  • Journal Title: Marine Ecology Progress Series Volume: 481 Pages: 199-209
  • DOI: 10.3354/meps10202
  • Peer Reviewed