Study of the phytoplankton plume dynamics off the Crozet Islands (Southern Ocean): A geochemical-physical coupled approach
|Author(s)||Sanial Virginie1, Van Beek Pieter1, Lansard Bruno2, D'Ovidio Francesco3, Kestenare Elodie1, Souhaut Marc1, Zhou Meng4, Blain Stephane5|
|Affiliation(s)||1 : Lab Etud Geophys & Oceanog Spatiales CNRS CNES IR, Observ Midi Pyrenees, Toulouse, France.
2 : Lab Sci Climat & Environm IPSL CEA CNRS UVSQ, Gif Sur Yvette, France.
3 : Lab Oceanog & Climat CNRS IRD UPMC MNHN, LOCEAN IPSL, Paris, France.
4 : Univ Massachusetts, Dept Environm Earth & Ocean Sci, Boston, MA 02125 USA.
5 : Lab Oceanog Microbienne CNRS UPMC, Observ Banyuls Sur Mer, Banyuls S Mer, France.
|Source||Journal Of Geophysical Research-oceans (0148-0027) (Amer Geophysical Union), 2014-04 , Vol. 119 , N. 4 , P. 2227-2237|
|WOS© Times Cited||13|
|Keyword(s)||Southern Ocean, Crozet Islands, iron fertilization, radium, altimetry, GEOTRACES|
|Abstract||The Crozet Archipelago, in the Indian sector of the Southern Ocean, constitutes one of the few physical barriers to the Antarctic Circumpolar Current. Interaction of the currents with the sediments deposited on the margins of these islands contributes to the supply of chemical elementsincluding iron and other micro-nutrientsto offshore high-nutrient, low-chlorophyll (HNLC) waters. This natural fertilization sustains a phytoplankton bloom that was studied in the framework of the KEOPS-2 project. In this work, we investigated the time scales of the surface water transport between the Crozet Island shelves and the offshore waters, a transport that contributes iron to the phytoplankton bloom. We report shelf-water contact ages determined using geochemical tracers (radium isotopes) and physical data based on in situ drifter data and outputs of a model based on altimetric Lagrangian surface currents. The apparent ages of surface waters determined using the three independent methods are in relatively good agreement with each other. Our results provide constraints on the time scales of the transport between the shelf and offshore waters near the Crozet Islands and highlight the key role played by horizontal transport in natural iron fertilization and in defining the extension of the chlorophyll plume in this HNLC region of the Southern Ocean. Key Points