title: Biological response to millennial variability of dust and nutrient supply in the Subantarctic South Atlantic Ocean.
abstract: Fluxes of lithogenic material and fluxes of three palaeo-productivity proxies (organic carbon, biogenic opal and alkenones) over the past 100,000 years were determined using the (230)Th-normalization method in three sediment cores from the Subantarctic South Atlantic Ocean. Features in the lithogenic flux record of each core correspond to similar features in the record of dust deposition in the EPICA Dome C ice core. Biogenic fluxes correlate with lithogenic fluxes in each sediment core. Our preferred interpretation is that South American dust, most probably from Patagonia, constitutes a major source of lithogenic material in Subantarctic South Atlantic sediments, and that past biological productivity in this region responded to variability in the supply of dust, probably due to biologically available iron carried by the dust. Greater nutrient supply as well as greater nutrient utilization (stimulated by dust) contributed to Subantarctic productivity during cold periods, in contrast to the region south of the Antarctic Polar Front (APF), where reduced nutrient supply during cold periods was the principal factor limiting productivity. The anti-phased patterns of productivity on opposite sides of the APF point to shifts in the physical supply of nutrients and to dust as cofactors regulating productivity in the Southern Ocean.
authors.affiliation: Lamont-Doherty Earth Observatory, Columbia University, PO Box 1000, Palisades, NY 10964, USA Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027, USA boba@ldeo.columbia.edu.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Anderson
authors.affiliation: School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Barker
authors.affiliation: Lamont-Doherty Earth Observatory, Columbia University, PO Box 1000, Palisades, NY 10964, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Fleisher
authors.affiliation: Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Gersonde
authors.affiliation: Lamont-Doherty Earth Observatory, Columbia University, PO Box 1000, Palisades, NY 10964, USA Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027, USA.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Goldstein
authors.affiliation: Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Kuhn
authors.affiliation: Institute of Environmental Science and Technology (ICTA), and Department of Geography, Universitat Autònoma de Barcelona (UAB), Edifici Cn, Campus UAB, Bellaterra 08193, Spain.
authors.forename: P Graham
authors.initials: PG
authors.lastname: Mortyn
authors.affiliation: Max Planck Research Group, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Carl-von-Ossietzky-Strasse 9-11, 26129 Oldenburg, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Pahnke
authors.affiliation: School of Oceanography, University of Washington, Seattle, WA 98195, USA.
authors.forename: Julian P
authors.initials: JP
authors.lastname: Sachs
mesh_terms: D000864:Antarctic Regions; D001267:Atlantic Ocean; D004391:Dust / Q000032:analysis*; D005502:Food; D019015:Geologic Sediments / Q000737:chemistry; D007501:Iron / Q000032:analysis; D008954:Models, Biological; D010839:Phytoplankton / Q000378:metabolism; D012623:Seawater / Q000737:chemistry*; D013997:Time Factors
chemical_list: D004391:Dust; D007501:Iron
keywords: Southern Ocean; biological productivity; dust; iron