@article{85322594aab84026b0b1bf56953d1d6c,
title = "Iron from a submarine source impacts the productive layer of the Western Tropical South Pacific (WTSP)",
abstract = "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.",
author = "C{\'e}cile Guieu and Sophie Bonnet and Anne Petrenko and Christophe Menkes and Val{\'e}rie Chavagnac and Karine Desboeufs and Christophe Maes and Thierry Moutin",
note = "Funding Information: This research is a contribution of the OUTPACE (Oligotrophy from Ultra-oligoTrophy PACific Experiment) project (https://outpace.mio.univ-amu.fr/), funded by the Agence Nationale de la Recherche (grant ANR-14-CE01-0007-01), the LEFE-CyBER program (CNRS-INSU), the Institut de Recherche pour le D{\'e}veloppement (IRD), the GOPS program (IRD) and the CNES (BC T23, ZBC 4500048836). The OUTPACE cruise (http:// dx.doi.org/10.17600/15000900) was managed by the MIO (OSU Institut Pytheas, AMU) from Marseille (France). The authors thank the crew of the R/V L{\textquoteright} Atalante for outstanding shipboard operations. We acknowledge the help of Justine Louis in collecting the seawater samples on board. The Argo data were collected and made freely available by the International Argo Program and the national programs that contribute to it (http://www.argo. ucsd.edu, http://argo.jcommops.org). The Argo Program is part of the Global Ocean Observing System. We are grateful to Gilles Rougier and Lucio Bellomo for the Argo floats deployment during the cruise. G. Rougier and M. Picheral are warmly thanked for their efficient help in CTD rosette management and data processing, as well as C. Schmechtig for the LEFE-CyBER database management. All data and metadata are available at the following web address: http://www.obs-vlfr.fr/proof/php/outpace/outpace.php. J. Resing and two anonymous reviewers are warmly thanked for their help in improving this manuscript. Publisher Copyright: {\textcopyright} 2018 The Author(s).",
year = "2018",
month = dec,
day = "1",
doi = "10.1038/s41598-018-27407-z",
language = "English (US)",
volume = "8",
journal = "Scientific Reports",
issn = "2045-2322",
publisher = "Nature Publishing Group",
number = "1",
}