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Open‐ocean convection process: A driver of the winter nutrient supply and the spring phytoplankton distribution in the N orthwestern M editerranean S ea
Author(s) -
Severin Tatiana,
Kessouri Faycal,
Rembauville Mathieu,
SánchezPérez Elvia Denisse,
Oriol Louise,
Caparros Jocelyne,
PujoPay Mireille,
Ghiglione JeanFrançois,
D'Ortenzio Fabrizio,
Taillandier Vincent,
Mayot Nicolas,
Durrieu De Madron Xavier,
Ulses Caroline,
Estournel Claude,
Conan Pascal
Publication year - 2017
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2016jc012664
Subject(s) - phytoplankton , biogeochemical cycle , spring bloom , convection , mixed layer , oceanography , environmental science , water column , nutrient , geology , atmospheric sciences , chemistry , environmental chemistry , meteorology , physics , organic chemistry
This study was a part of the DeWEX project ( De ep W ater formation Ex periment), 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.