Chemical limitations on phytoplankton growth in the Crozet Basin, Subantarctic Southern Ocean.

• Main Authors: Sedwick, Peter, Blain, Stéphane, Queguiner, Bernard, Griffiths, Brian, Fiala, Michel, Bucciarelli, Eva, Denis, Michel
• Other Authors: Bermuda Biological Station for Research (BBSR), Bermuda Biological Station for Research, Institute of Antarctic and Southern Ocean Studies (IASOS), University of Tasmania Hobart, Australia (UTAS), Laboratoire d'océanographie et de biogéochimie (LOB), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Division of Marine and Atmospheric Research (CSIRO), Commonwealth Scientific and Industrial Research Organisation Canberra (CSIRO), Laboratoire d'océanographie biologique de Banyuls (LOBB), Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de MicrobiologiE de Géochimie et d'Ecologie Marines (LMGEM), Université de la Méditerranée - Aix-Marseille 2-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2002
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Southern Ocean; Indian
• Online Access: https://hal.science/hal-00480622

International audience To evaluate the sufficiency of ambient iron and nutrient levels for algal growth in surface waters of the Crozet Basin, in the Indian-Subantarctic region of the Southern Ocean, shipboard iron- and nutrient-addition bottle-incubation experiments were performed during the Antares-IV campaign in January-February 1999. The experiments were conducted with plankton collected from near-surface (~20 m depth) waters at three locations between 43-46°S and 61-65°E, each characterised by relatively low algal biomass (0.2-0.7 µg L-1 chlorophyll a) and dissolved iron concentrations (~0.1-0.3 nM): (1) the Polar Frontal Zone (~19 µM nitrate and 1.2 µM silicate), (2) the confluence of the Subantarctic and Subtropical Fronts (~5.4 µM nitrate and 0.5 µM silicate), and (3) the Subtropical Zone north of the Agulhas Front (< 0.1 µM nitrate and ~1.4 µM silicate). Our experimental results demonstrate three different regimes of chemical limitation on phytoplankton production and community structure within this small oceanic area: in the Polar Frontal Zone, primary limitation of community production by iron deficiency, and secondary limitation of diatom production by silicate deficiency; within the Subantarctic-Subtropical Frontal Zone, primary and secondary limitation of community production by deficiencies in iron and silicate, respectively; and within the southern Subtropical Zone, primary and secondary limitation of community production by deficiencies in nitrate/phosphate and iron, respectively.