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, AR, Lannuzel, D, Remenyi, TA, Wagener, T, Lam, PJ, Boyd, PW, Guieu, C, Townsend, AT, Trull, T
• Format: Article in Journal/Newspaper
• Language: English
• Published: Amer Geophysical Union 2009
• Subjects: Earth Sciences; Oceanography; Chemical Oceanography; Southern Ocean
• Online Access: http://www.agu.org/; https://doi.org/10.1029/2009GB003500; http://ecite.utas.edu.au/62060

Climate change is projected to significantly alter the delivery (stratification, boundarycurrents, aridification of landmasses, glacial melt) of iron to the Southern Ocean. Wereport the most comprehensive suite of biogeochemical iron budgets to date for threecontrasting sites in subantarctic and polar frontal waters south of Australia. Distinctregional environments were responsible for differences in the mode and strength of ironsupply mechanisms, with higher iron stocks and fluxes observed in surface northernsubantarctic waters, where atmospheric iron fluxes were greater. Subsurface waterssoutheast of Tasmania were also enriched with particulate iron, manganese andaluminum, indicative of a strong advective source from shelf sediments. Subantarcticphytoplankton blooms are thus driven by both seasonal iron supply from southwardadvection of subtropical waters and by wind-blown dust deposition, resulting in a strongdecoupling of iron and nutrient cycles. We discuss the broader global significance ouriron budgets for other ocean regions sensitive to climate-driven changes in iron supply.