HR: 0800h
AN: PP21C-1568    [Abstracts]
TI: Assessing the Paleoceanographic Potential of the Coral Montipora venosa at Fanning Atoll, Central Equatorial Pacific
AU: * Stolorow, A M
EM: as1341@albany.edu
AF: Department of Earth and Atmospheric Sciences, University at Albany, 1400 Washington Ave., Albany, NY 12222 United States
AU: Linsley, B K
EM: blinsley@albany.edu
AF: Department of Earth and Atmospheric Sciences, University at Albany, 1400 Washington Ave., Albany, NY 12222 United States
AU: Dunbar, R B
EM: dunbar@stanford.edu
AF: Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305 United States
AB: The paleoceanographic significance of the modes of variability in coral geochemical time-series are strengthened by replicating these reconstructed signals in other corals or paleo-archives. At present, the coral Porites is the genus most commonly studied in the Pacific. Porites has the advantage of wide geographic extent, high growth rates of ~10-20mm/yr, and deposition of continuous skeletal records 200 to 500 years in length. However, identified and/or proposed potential problems with utilizing Porites colonies include boring by marine organisms, diagenetic overprinting of primary geochemical signals, and skeletal growth-related artifacts. This has led to some uncertainty in interpretation of lower frequency modes of variability in Porites geochemical series. To date, published single colony Porites records in the central and western equatorial Pacific extend back to only the 1850's, demonstrating the need for the development of other archives in this region. Here we present oxygen isotopic (δ¹⁸O) data generated from a colony of the massive hermatypic coral Montipora venosa, a genus not previously studied, from Fanning Island (3°52'N, 159°20'W) in the central Pacific Line Islands. The coral record is 650mm in length and spans 111 yr (1997-1887; 5.9mm/yr). Comparison of the M. venosa record to a Porites δ¹⁸O (12 samples/yr) record cored ~4m away demonstrates that the slower growth of M. venosa does not affect the reconstruction of annual and interannual oceanographic variability (time and amplitude). There are, however, some significant differences in δ¹⁸O values over time. In particular, a decadal 0.3-0.4 ‰ increase in δ¹⁸O in the Fanning Porites record from 1945-1953 is not recorded in the Fanning Montipora or in Tarawa (1°3'N, 172°E), Palmyra (5°52'N, 162°W), and Maiana (1°N, 173°E) Porites δ¹⁸O records. This difference suggests some undetermined anomaly in the Fanning Porites record and supports the need for a replication strategy. In addition, correlation of the Ni~{n}o 3.4 Index with the M. venosa δ¹⁸O record has an R=0.55, comparable to coral δ¹⁸O records from Palmyra, Maiana, and Tarawa, indicating that this Montipora venosa colony has recorded accurately variations in ENSO over the last century.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 4870 Stable isotopes (0454, 1041)
DE: 4916 Corals (4220)
DE: 4922 El Nino (4522)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005