Carbon and Oxygen Isotope Records of Tridacna squamosa Shells from two Different Latitudes in the Ryukyu Islands

2021 ◽  
Vol 25 (2) ◽  
Author(s):  
Satoshi Kodama ◽  
Hideko Takayanagi ◽  
Kosuke Yoshii ◽  
Thuy Thi Nhu Ha ◽  
Ryuji Asami ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Ryukyu Islands ◽  
Carbon And Oxygen Isotope ◽  
The Ryukyu Islands ◽  
Tridacna Squamosa

scholarly journals Reconstruction of ocean environment time series since the late nineteenth century using sclerosponge geochemistry in the northwestern subtropical Pacific

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ryuji Asami ◽  
Taketo Matsumori ◽  
Ryuichi Shinjo ◽  
Ryu Uemura ◽  
Yuki Miyaoka ◽  
...  
Keyword(s):  
Nineteenth Century ◽  
Time Series ◽  
Atmospheric Aerosols ◽  
Late Nineteenth Century ◽  
Ryukyu Islands ◽  
Okinawa Island ◽  
Carbon And Oxygen Isotope ◽  
The Ryukyu Islands ◽  
Decadal Variations ◽  
Late Nineteenth

AbstractThe geochemistry of calcifying marine organisms is an excellent proxy for reconstructing paleoceanographic history, but studies of hypercalcified demosponges (sclerosponges) are considerably fewer than those of corals, foraminifers, and bivalves. For this study, we first generated near-annual resolved stable carbon and oxygen isotope (δ13C and δ18O) and element/Ca ratios (Sr/Ca, Ba/Ca, Pb/Ca, U/Ca) time series for 1880–2015 from sclerosponge samples (Acanthochaetetes wellsi) collected at Miyako Island and Okinawa Island in the Ryukyu Islands of southwestern Japan. The δ13C records exhibited a typical variation of anthropogenically derived Suess effects, demonstrating that the rates of decrease of –0.0043‰/year before 1960 and – 0.024‰/year after 1960 in the northwestern subtropical Pacific were respectively similar to and about 1.4 times higher than those of the Caribbean Sea in the tropical Atlantic. Spectral analysis of the δ18O time series revealed significant periodicity of approximately 2, 3, 6.5, 7–10, and 20–30 year/cycle, indicating that sea surface conditions in the southern Ryukyu Islands had been dominated by interannual and decadal variations in temperature and seawater δ18O since the late nineteenth century. The Sr/Ca and U/Ca ratios for the species A. wellsi (high-Mg calcite) might not be a robust proxy for seawater temperatures, unlike Astrosclera willeyana and Ceratoporella nicholsoni sclerosponges (aragonite). An evident increasing Pb/Ca trend after 1950 found in the samples is probably attributable to Pb emissions from industrial activities and atmospheric aerosols in eastern Asian countries. The Ba/Ca variations differ greatly among sampling sites, which might be attributable to the respective local environments. This evidence demonstrates that more high-resolution age determinations and geochemical profilings enable delineation of secular variations in ocean environments on annual and interannual timescales. Results of our study suggest that if sclerosponges living in deeper ocean environments are collected, spatial and vertical oceanographic variations for the last several centuries will be reconstructed along with coral proxy records.

scholarly journals Carbon- and oxygen-isotope compositions of a modern deep-water brachiopod Campagea japonica collected off Aguni-jima, Central Ryukyu Islands, southwestern Japan

2012 ◽  
Vol 46 (2) ◽  
pp. 77-87 ◽  
Author(s):  
HIDEKO TAKAYANAGI ◽  
RYUJI ASAMI ◽  
OSAMU ABE ◽  
HIROYUKI KITAGAWA ◽  
TOSHIHIRO MIYAJIMA ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Deep Water ◽  
Ryukyu Islands ◽  
Carbon And Oxygen Isotope

ESR ages of middle Pleistocene corals from the Ryukyu islands

1991 ◽  
Vol 36 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Sumiko Ikeda ◽  
Masao Kasuya ◽  
Motoji Ikeya
Keyword(s):  
Electron Spin Resonance ◽  
Oxygen Isotope ◽  
Electron Spin ◽  
Middle Pleistocene ◽  
Ryukyu Islands ◽  
The Ryukyu Islands ◽  
Spin Resonance ◽  
Lowermost Part

AbstractElectron spin resonance ages of 11 corals from the lower part of the Ryukyu Group, Japan can be classified into two groups (about 600,000 and 800,000 yr). The result indicates that the lower part of the Ryukyu Group is correlated to at least two of the oxygen isotope stages 15, 17, 19, 21, and 23. Lowermost part of the Ryukyu Group was probably deposited during a large transgression and may be correlated worldwide.

Monthly Water Exchange through the Ryukyu Islands Revealed by Salinity Structural Changes

2013 ◽  
Vol 864-867 ◽  
pp. 2335-2339
Author(s):  
Ya Pan Liu ◽  
Jian Cheng Kang ◽  
Jiong Zhu ◽  
Qin Chen Han
Keyword(s):  
Structural Changes ◽  
Water Exchange ◽  
High Salinity ◽  
World Ocean ◽  
Core Layer ◽  
Ryukyu Islands ◽  
High Salinity Water ◽  
The Ryukyu Islands ◽  
Salinity Water ◽  
World Ocean Atlas

Using salinity database of World Ocean Atlas 2009 (WOA09) issued by NOAA in 2010, refer the range of high-salinity tongue to indicate the strength about high-salinity water, from the perspective of structural changes of salinity; the water exchange through Ryukyu Islands upper 500 m have been analyzed, the results show that: due to Ryukyu Trough, currents on both sides of Ryukyu Islands occur exchange, for upper 500 m, high-salinity water in east of the Ryukyu Islands mainly invade the west waterthe Kuroshio in East China Sea; the intrusion strength is powerful from the depth of 100 m to 200 m, and the 150 m layer is the core layer of high-salinity water intrusion; the high-salinity water at the east of Ryukyu Islands invades the Kuroshio are stronger in March, May, June, September, October and November, are weaker in April and December.

Stable carbon and oxygen isotope compositions of extant crinoidal echinoderm skeletons

2012 ◽  
Vol 291 ◽  
pp. 132-140 ◽  
Author(s):  
Przemysław Gorzelak ◽  
Jarosław Stolarski ◽  
Krzysztof Małkowski ◽  
Anders Meibom
Keyword(s):  
Oxygen Isotope ◽  
Stable Carbon ◽  
Carbon And Oxygen Isotope

The comparative yields of two types of leucaena (Peruvian v. Hawaiian) grown for forage production in Ryukyu Islands

1986 ◽  
Vol 106 (3) ◽  
pp. 623-624 ◽  
Author(s):  
Y. Kitamura
Keyword(s):  
Leucaena Leucocephala ◽  
Ryukyu Islands ◽  
Forage Production ◽  
High Quality ◽  
The Ryukyu Islands

Leucaena leucocephala (Lam.) de Wit, a leguminous shrub, has come into use as a fodder plant for animals in the Ryukyu Islands as it provides highly palatable, high quality feed (Kitamura, 1985). It is superior to other feeds available in this regard (Higashiohmine, Aramoto & Yamashiro, 1971; Isa et al. 1982).

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