Iron from a submarine source impacts the productive layer of the Western Tropical South Pacific (WTSP)
|Author(s)||Guieu Cecile1, 2, Bonnet Sophie3, Petrenko Anne3, Menkes Christophe4, Chavagnac Valerie5, Desboeufs Karine6, Maes Christophe7, Moutin Thierry3|
|Affiliation(s)||1 : Sorbonne Univ, CNRS, LOV, F-06230 Villefranche Sur Mer, France.
2 : New York Univ Abu Dhabi, Ctr Prototype Climate Modeling, Abu Dhabi, U Arab Emirates.
3 : Univ Toulon & Var, Observ Sci Univers Pytheas, Inst Rech Dev,Aix Marseille Univ, CNRS,Inst Natl Sci Univers,MIO, F-13288 Marseille, France.
4 : Sorbonne Univ, CNRS, LOCEAN, MNHN,IRD, BP A5, Noumea 98848, New Caledonia.
5 : Univ Toulouse, Geosci Environm Toulouse, CNRS, UPS,IRD,CNES, F-31400 Toulouse, France.
6 : UPD, UPEC, IPSL, LISA, Creteil, France.
7 : Univ Brest, CNRS, IUEM, IRD,LOPS,IFREMER, Brest, France.
|Source||Scientific Reports (2045-2322) (Nature Publishing Group), 2018-06 , Vol. 8 , N. 1 , P. 9075 (9p.)|
|WOS© Times Cited||23|
In the Western Tropical South Pacific, patches of high chlorophyll concentrations linked to the occurrence of N2-fixing organisms are found in the vicinity of volcanic islands. The survival of these organisms relies on a high bioavailable iron supply whose origin and fluxes remain unknown. Here, we measured high dissolved iron (DFe) concentrations (up to 66 nM) in the euphotic layer, extending zonally over 10 degrees longitude (174 E−175 W) at ∼20°S latitude. DFe atmospheric fluxes were at the lower end of reported values of the remote ocean and could not explain the high DFe concentrations measured in the water column in the vicinity of Tonga. We argue that the high DFe concentrations may be sustained by a submarine source, also characterized by freshwater input and recorded as salinity anomalies by Argo float in situ measurements and atlas data. The observed negative salinity anomalies are reproduced by simulations from a general ocean circulation model. Submarine iron sources reaching the euphotic layer may impact nitrogen fixation across the whole region.