TERRAPUB Geochemical Journal

Geochemical Journal, Vol. 48 (No. 4), pp. e9-e14, 2014


Skeletal isotopic responses of the Scleractinian coral Isopora palifera to experimentally controlled water temperatures

Kozue Nishida1, Akira Iguchi2, Toyoho Ishimura3, Kazuhiko Sakai4 and Atsushi Suzuki1*

1Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8567, Japan
2Department of Bioresources Engineering, Okinawa National College of Technology, Okinawa, Japan
3Department of Chemistry and Material Engineering, Ibaraki National Collage of Technology, Hitachinaka, Japan
4Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Okinawa, Japan

(Received March 25, 2014; Accepted May 14, 2014; Online published June 23, 2014)

Abstract: We cultivated Isopora palifera clone colonies at six different temperatures for testing the utility of its skeletal δ18O as a paleotemperature proxy. Specimens cultivated at higher temperatures exhibited lower calcification rates, especially at 31.0°C, than those cultured at lower temperatures. The skeletal δ18O of the specimens cultured at 21.1-29.5°C correlated strongly with water temperature, and δ18O-temperature sensitivity was -0.15‰ °C-1. When we removed the thermal factor from the skeletal δ18O and δ13C trends at 21.1-29.5°C by subtracting the estimated equilibrium values of inorganic aragonite from the analyzed δ18O and δ13C values, we found that the calcification rate variation has little influence on the isotopic compositions of the specimens examined. Thus, the skeletal δ18O of I. palifera corals without severe bleaching can be a good temperature proxy at temperatures below ∼30°C.
Key words: stable isotopes, coral, calcification, bleaching, temperature experiment

*Corresponding author E-mail: a.suzuki@aist.go.jp

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