Open-ocean convection process: A driver of the winter nutrient supply and the spring phytoplankton distribution in the Northwestern Mediterranean Sea

Type : ACL
Nature : Production scientifique
Au bénéfice du Laboratoire : Oui
Statut de publication : Publié
Année de publication : 2017
Auteurs (15) : SEVERIN Tatiana KESSOURI Fayçal REMBAUVILLE Mathieu SANCHEZ-PEREZ E,d ORIOL L CAPARROS Jocelyne PUJO-PAY Mireille GHIGLIONE J,f D'ORTENZIO Fabrizio TAILLANDIER Vincent MAYOT Nicolas DURRIEU DE MADRON Xavier ULSES Caroline ESTOURNEL Claude CONAN Pascal
Revue scientifique : Journal of Geophysical Research-Oceans
Volume : 122
Fascicule : 6
Pages : 4587-4601
DOI : 10.1002/2016JC012664
URL : https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016JC012664
Abstract : Abstract This study was a part of the DeWEX project (Deep Water formation Experiment), designed to better understand the impact of dense water formation on the marine biogeochemical cycles. Here, nutrient and phytoplankton vertical and horizontal distributions were investigated during a deep open-ocean convection event and during the following spring bloom in the Northwestern Mediterranean Sea (NWM). In February 2013, the deep convection event established a surface nutrient gradient from the center of the deep convection patch to the surrounding mixed and stratified areas. In the center of the convection area, a slight but significant difference of nitrate, phosphate and silicate concentrations was observed possibly due to the different volume of deep waters included in the mixing or to the sediment resuspension occurring where the mixing reached the bottom. One of this process, or a combination of both, enriched the water column in silicate and phosphate, and altered significantly the stoichiometry in the center of the deep convection area. This alteration favored the local development of microphytoplankton in spring, while nanophytoplankton dominated neighboring locations where the convection reached the deep layer but not the bottom. This study shows that the convection process influences both winter nutrients distribution and spring phytoplankton distribution and community structure. Modifications of the convection's spatial scale and intensity (i.e., convective mixing depth) are likely to have strong consequences on phytoplankton community structure and distribution in the NWM, and thus on the marine food web.
Mots-clés : open-ocean convection, nutrient, stoichiometry, phytoplankton size class, Northwestern Mediterranean Sea
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Citation :
Severin T, Kessouri F, Rembauville M, Sanchez-Perez ED, Oriol L, Caparros J, Pujo-Pay M, Ghiglione JF, D'Ortenzio F, Taillandier V, Mayot N, Durrieu de Madron X, Ulses C, Estournel C, Conan P (2017) Open-ocean convection process: A driver of the winter nutrient supply and the spring phytoplankton distribution in the Northwestern Mediterranean Sea. J Geophys Res-Oceans 122: 4587-4601 | doi: 10.1002/2016JC012664