Biogeochemical iron budgets of the Southern Ocean south of Australia: Decoupling of iron and nutrient cycles in the subantarctic zone by the summertime supply

• Published in: Global Biogeochemical Cycles
• Main Authors: Bowie, Andrew, Lannuzel, Delphine, Remenyi, Tomas, Wagener, Thibaut, Lam, Phoebe, Boyd, Philip, Guieu, Cécile, Townsend, Ashley, Trull, Thomas
• Other Authors: Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), Woods Hole Oceanographic Institution (WHOI), National Institute of Water and Atmospheric Research Wellington (NIWA), CSIRO Marine and Atmospheric Research (CSIRO-MAR), Commonwealth Scientific and Industrial Research Organisation Canberra (CSIRO)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Southern Ocean
• Online Access: https://hal.archives-ouvertes.fr/hal-02567536; https://hal.archives-ouvertes.fr/hal-02567536/document; https://hal.archives-ouvertes.fr/hal-02567536/file/2009GB003500.pdf; https://doi.org/10.1029/2009GB003500

International audience Climate change is projected to significantly alter the delivery (stratification, boundary currents, aridification of landmasses, glacial melt) of iron to the Southern Ocean. We report the most comprehensive suite of biogeochemical iron budgets to date for three contrasting sites in subantarctic and polar frontal waters south of Australia. Distinct regional environments were responsible for differences in the mode and strength of iron supply mechanisms, with higher iron stocks and fluxes observed in surface northern subantarctic waters, where atmospheric iron fluxes were greater. Subsurface waters southeast of Tasmania were also enriched with particulate iron, manganese and aluminum, indicative of a strong advective source from shelf sediments. Subantarctic phytoplankton blooms are thus driven by both seasonal iron supply from southward advection of subtropical waters and by wind-blown dust deposition, resulting in a strong decoupling of iron and nutrient cycles. We discuss the broader global significance our iron budgets for other ocean regions sensitive to climate-driven changes in iron supply.