[BPT03-P03] Paleoceanographic proxy and skeletal records of sclerosponges from the Ryukyu Islands, Japan
Keywords:sclerosponge, skeleton, proxy, oxygen isotope composition, carbon isotope composition, paleocean
Here we present oxygen and carbon isotope records from sclerosponges (Astrosclera willeyana and Acanthochaetetes wellsi) collected from Kume-jima, Okinawa-jima and Miyako-jima, Ryukyu Islands in the North Pacific. In order to evaluate the utility of sclerosponge as an environmental proxy, within-skeleton and intraspecific variations in stable isotopic records of 37 samples were investigated. Soft X-ray images of large-size sclerosponges showed highly developed skeletal growth bands with >100 high/low density layers. The secular changes in radiocarbon-dated time series of the sclerosponge carbon records were consistent with previously reported data from Atlantic and Pacific corals and sclerosponges. The long-term oxygen isotopic trends of the samples are characterized by slight depletions throughout their living periods, indicative of an overall trend toward warmer ocean environment around the Ryukyu Islands. Our sclerosponge-based estimates of sea surface temperature and salinity may document thermal and hydrologic variations in the Ryukyu Islands, furthering a better understanding of northwestern tropical-subtropical Pacific climate change for the last several centuries in conjunction with coral-based long proxy records.
Benavides and Druffel (1986) Coral Reefs, 4, 221-224.
Grottoli et al. (2010) J. Geophys. Res., 115, doi:10.1029/2009JC005586.
Swart et al. (2010) Geophys. Res. Lett., 37, doi:10.1029/2009GL041397.