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Impact of an intense water column mixing (0–1500 m) on prokaryotic diversity and activities during an open‐ocean convection event in the NW Mediterranean Sea
Author(s) -
Severin Tatiana,
Sauret Caroline,
Boutrif Mehdi,
Duhaut Thomas,
Kessouri Fayçal,
Oriol Louise,
Caparros Jocelyne,
PujoPay Mireille,
Durrieu de Madron Xavier,
Garel Marc,
Tamburini Christian,
Conan Pascal,
Ghiglione JeanFrançois
Publication year - 2016
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.13324
Subject(s) - water column , convection , stratification (seeds) , biogeochemical cycle , biology , oceanography , convective mixing , thermohaline circulation , biogeochemistry , homogenization (climate) , mediterranean sea , mediterranean climate , ecology , geology , seed dormancy , biodiversity , physics , germination , botany , dormancy , thermodynamics
Summary Open‐ocean convection is a fundamental process for thermohaline circulation and biogeochemical cycles that causes spectacular mixing of the water column. Here, we tested how much the depth‐stratified prokaryotic communities were influenced by such an event, and also by the following re‐stratification. The deep convection event (0–1500 m) that occurred in winter 2010–2011 in the NW Mediterranean Sea resulted in a homogenization of the prokaryotic communities over the entire convective cell, resulting in the predominance of typical surface Bacteria, such as Oceanospirillale and Flavobacteriales . Statistical analysis together with numerical simulation of vertical homogenization evidenced that physical turbulence only was not enough to explain the new distribution of the communities, but acted in synergy with other parameters such as exported particulate and dissolved organic matters. The convection also stimulated prokaryotic abundance (+21%) and heterotrophic production (+43%) over the 0–1500 m convective cell, and resulted in a decline of cell‐specific extracellular enzymatic activities (−67%), thus suggesting an intensification of the labile organic matter turnover during the event. The rapid re‐stratification of the prokaryotic diversity and activities in the intermediate layer 5 days after the intense mixing indicated a marked resilience of the communities, apart from the residual deep mixed water patch.