HR: 0800h
AN: OS11A-0180    [Abstracts]
TI: Surface water saturation state and calcareous nannoplankton production across the Paleocene-Eocene Thermal Maximum
AU: * Gibbs, S
EM: sxg@noc.soton.ac.uk
AF: School of Ocean and Earth Sciences, National Oceanography Centre, European Way, Southampton, SO14 3ZH, United Kingdom
AU: Stoll, H
EM: hstoll@geol.uniovi.es
AF: Geosciences Department, Williams College, Williamstown, MA 01267, United States
AU: Bralower, T
EM: bralower@geosc.psu.edu
AF: Department of Geosciences, Pennsylvania State, Deike Building, University Park, PA 16802, United States
AU: Bown, P
EM: p.bown@ucl.ac.uk
AF: UniversityDepartment of Earth Sciences, University College London, Gower Street, London, WC1E 6BT, United Kingdom
AB: The release of massive amounts of carbon to the ocean-atmosphere system at the Paleocene-Eocene Thermal Maximum (PETM, approximately 55 Ma) has particular relevance today because of the devastating effects that rising atmospheric CO₂ and surface water acidification may cause to calcifying organisms such as coccolithophores and corals. Widespread carbonate dissolution at the onset of the PETM is striking evidence for deep ocean acidification at this time. Here, we address whether ocean acidification also affected the production of biogenic carbonate in surface waters. By the novel combination of nannofossil abundance counts and taxon- specific Sr/Ca data we have reconstructed original calcareous nannoplankton production at the Ocean Drilling Program (ODP) Sites 690 (Southern Ocean) and 1209 (paleoequatorial Pacific) and the New Jersey shelf site ODP Leg 174X drillhole at Bass River. Nannoplankton production records at all three sites are decoupled from changes in bottom water chemistry with no evidence for interruption of carbonate production by phytoplankton on geological timescales, even at high latitudes which we would expect to be sensitive to surface water acidification. Therefore, although we cannot rule out that calcification could have been inhibited for less than 1000 years at the event onset, we can conclude that there was no long-term detrimental impact on the surface water calcifying community.
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4912 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4805)
DE: 4944 Micropaleontology (0459, 3030)
DE: 4948 Paleocene/Eocene thermal maximum
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting