Grottoli, Andréa G. and Adkins, Jess F. and Panero, Wendy R. and Reaman, Daniel M. and Moots, Kate (2010) Growth rates, stable oxygen isotopes (δ^(18)O), and strontium (Sr/Ca) composition in two species of Pacific sclerosponges (Acanthocheatetes wellsi and Astrosclera willeyana) with δ^(18)O calibration and application to paleoceanography. Journal of Geophysical Research C, 115 . C06008. ISSN 0148-0227 http://resolver.caltech.edu/CaltechAUTHORS:20100629-165404339
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The isotopic and elemental composition of sclerosponge skeletons is used to reconstruct paleoceanographic records. Yet few studies have systematically examined the natural variability in sclerosponge skeletal δ^(18)O, growth, and Sr/Ca, and how that may influence the interpretation of sclerosponge proxy records. Here, we analyzed short records in seven specimens of Acanthocheatetes wellsi (high-Mg calcite, 21 mol% Mg) from Palau, four A. wellsi (high-Mg calcite, 21 mol% Mg) from Saipan, and three Astrosclera willeyana (aragonite) sclerosponges from Saipan, as well as one long record in an A. wellsi specimen from Palau spanning 1945–2001.5. In Saipan, species-specific and mineralogical effects appear to have a negligible effect on sclerosponge δ^(18)O, facilitating the direct comparison of δ^(18)O records between species at a given location. At both sites, A. wellsi δ^(18)O and growth rates were sensitive to environmental conditions, but Sr/Ca was not sensitive to the same conditions. High-resolution δ^(18)O analyses confirmed this finding as both A. wellsi and A. willeyana deposited their skeleton in accordance with the trends in isotopic equilibrium with seawater, though with a 0.27‰ offset in the case of A. willeyana. In the high-Mg-calcite species A. wellsi, Mg may be interfering with Sr incorporation into the skeleton. On multidecadal timescales, A. wellsi sclerosponge δ^(18)O in Palau tracked the Southern Oscillation Index variability post-1977, but not pre-1977, coincident with the switch in the Pacific Decadal Oscillation (PDO) at ~1976. This suggests that water mass circulation in the region is influenced by El Niño— Southern Oscillation variability during positive PDO phases, but not during negative ones.
|Additional Information:||© 2010 American Geophysical Union. Received 21 June 2009; accepted 4 January 2010; published 12 June 2010. We thank the following people and organizations for their assistance: J. Bauer, M. Cathey, P. Colin, R. Fairbanks, O. Gibb, D. Idip, T. Isamu, J. Kloulechad, J. Moots, J. Palardy, D. Purcell, R. Richmond, S. Takahashi, Palau International Coral Reef Center, Coral Reef Research Foundation, Palau Division of Marine Resources, Palau Ministry of Resources and Development, Commonwealth of the Northern Mariana Islands (CNMI) Division of Fish and Wildlife, CNMI Department of Environmental Quality, CNMI Coastal Resources Management, and the University of Guam. FTIR measurements were made by W.R.P. and D.M.R. at the U2A beamline of the National Sychrotron Light Source at Brookhaven National Lab (DOE BES DE‐AC02‐98CH10886) with the support of COMPRES (NSF EAR 06‐4958). Major funding for this work was provided to A.G.G. by the American Society for Mass Spectrometry, the Mellon Foundation, and the National Science Foundation (Chemical Oceanography, OCE0426022 and OCE0610487).|
|Subject Keywords:||sclerosponge; oxygen isotopes (δ^(18)O); paleoceanography|
|Official Citation:||Grottoli, A. G., J. F. Adkins, W. R. Panero, D. M. Reaman, and K. Moots (2010), Growth rates, stable oxygen isotopes (δ18O), and strontium (Sr/Ca) composition in two species of Pacific sclerosponges (Acanthocheatetes wellsi and Astrosclera willeyana) with δ18O calibration and application to paleoceanography, J. Geophys. Res., 115, C06008, doi:10.1029/2009JC005586|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||19 Jul 2010 17:22|
|Last Modified:||26 Dec 2012 12:11|
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