Paleoenvironmental analyses of sclerosponges: Toward reconstructing spatial variability of coral reef environments using multi-proxies

2016 Fiscal Year Final Research Report

• Project/Area Number: 26550012
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Environmental dynamic analysis
• Research Institution: University of the Ryukyus
• Principal Investigator: ASAMI Ryuji 琉球大学, 理学部, 准教授 (00400242)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 硬骨海綿 / サンゴ礁 / 環境解析 / プロキシ / 水温 / 塩分 / 化石燃料

Outline of Final Research Achievements

Sclerosponges from the Ryukyu Islands, southwestern Japan, were investigated to evaluate the utility as a paleoenvironmental proxy and to reconstruct long-term variability of ocean environment. In this study, field surveys and geochemical analyses were performed. Results showed that within-skeletal and intraspecific variations of sclerosponges are slight and the aragonite skeleton is precipitated in isotopic equilibrium with seawater at the living site. The radiometric age determination yielded time series of stable carbon and oxygen isotopic composition of sclerosponges for the last 150 years, showing significant variability of fossil fuel CO2 input into the ocean and seawater temperature/salinity. Coupled with the geochemistry of marine calcified organisms living in shallow waters, sclerosponge-based reconstruction of deeper ocean environments can elucidate spatial and vertical environmental changes for the past.

Free Research Field

古環境学