HR: 0800h
AN: PP31B-1524    [Abstracts]
TI: Intercolony variability of skeletal oxygen and carbon isotope ratios of corals: temperature-controlled tank experiment and field observation
AU: * Suzuki, A
EM: a.suzuki@aist.go.jp
AF: Geological Survey of Japan/AIST, AIST Tsukuba Central 7, 1-1-1 Higashi, Tsukuba, 305-8567 Japan
AU: Omata, T
EM: omatat@jamstec.go.jp
AF: Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 natsushima, Yokosuka, 237-0061 Japan
AU: Kawahata, H
EM: kawahata@ori.u-tokyo.ac.jp
AF: Ocean Research Institute, University of Tokyo, 1-15-1 Minamidai, Nakano, Tokyo, 164-8639 Japan
AB: We conducted tank experiments in which we grew Porites spp. colonies in thermostated seawater at five temperature settings under moderate light intensity. A skeletal isotope microprofiling technique applied along the major growth axis of each colony revealed that the oxygen isotope ratios of newly deposited skeleton in most colonies remained almost constant during tank incubation. However, the oxygen isotope ratios displayed a surprisingly large intercolony variability (~1‰ at each temperature setting) although the mean slope obtained for the temperature - skeletal oxygen isotope ratio relationship was close to previous results. The variations in the oxygen isotope ratios were apparently caused by kinetic isotope effects related to variations in the skeletal growth rate rather than by species-specific variability or genetic differences within species. Carbon isotope ratios showed significantly inverse correlation with linear growth rates, suggesting a kinetic isotope control at low growth rates. We also examined oxygen and carbon isotope ratios of Porites corals collected from coral reefs of southern Ryukyu Islands, Japan. In shallow faster-growing corals, oxygen and carbon isotope ratios showed out-of-phase annual fluctuations. In contrast, in deep slower growing corals (mean annual linear extension < 4.8 mm yr₁), oxygen and carbon isotope fluctuations were in phase, which has been identified as a pattern influenced by kinetic isotope effects. The slower growing corals were strongly influenced, and the faster growing corals weakly influenced, by kinetic isotope effects over metabolic isotope effects. Growth-rate-related kinetic isotope effects found in both the cultured corals and the deep slower-growing corals may be, at least partly, attributed to low light condition.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 4870 Stable isotopes (0454, 1041)
DE: 4872 Symbiosis
DE: 4916 Corals (4220)
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005