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A 60-year isotopic record from a mid-Holocene fossil giant clam (Tridacna gigas) in the Ryukyu Islands: physiological and paleoclimatic implications

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Title: A 60-year isotopic record from a mid-Holocene fossil giant clam (Tridacna gigas) in the Ryukyu Islands: physiological and paleoclimatic implications
Authors: Watanabe, Tsuyoshi Browse this author →KAKEN DB
Suzuki, Atsushi Browse this author
Kawahata, Hodaka Browse this author
Kan, Hironobu Browse this author
Ogawa, Shinji Browse this author
Keywords: Tridacna gigas
Oxygen isotope
Carbon isotope
Growth line
Mid-Holocene
Issue Date: 30-Sep-2004
Publisher: Elsevier
Journal Title: Palaeogeography, Palaeoclimatology, Palaeoecology
Volume: 212
Issue: 3-4
Start Page: 343
End Page: 354
Publisher DOI: 10.1016/j.palaeo.2004.07.001
Abstract: We have constructed a 60-year stable isotope record from a 14C-dated fossil giant clam, Tridacna gigas (6216 years BP), at its northernmost latitudinal limit in the geological past, on Kume Island, Central Ryukyu Archipelago, Japan. Stable oxygen (δ18O) and carbon (δ13C) isotopic analyses are combined with observations of growth lines seen on the inner shell layer. Sixty pairs of summer/winter growth lines, which preserve daily growth increments were observed in the inner shell layer. Two growth phases, characterized by a growth curve and isotopic profiles, are clearly recognized throughout the growth history of this specimen. No significant shifts in average values of the two isotopic ratios were detected during its growth history, although the growth rate varied widely from 1 to 15 mm/year over 60 years, including after the onset of sexual maturity. Spectral analysis of the fossil Tridacna δ18O time-series implies that decadal variability observed in the North Pacific Ocean during the past hundred years also existed 6000 years ago. Our study implies that fossil giant clams are one of the best means of inferring isotopic records of annual to decadal climate variations. Giant clams have the advantages of a dense shell, high growth rate, long lifespan, and geographically and geologically broad distributions.
Type: article (author version)
URI: http://hdl.handle.net/2115/56414
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 渡邊 剛

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