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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
| 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)
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Submitter: 渡邊 剛
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