Contrasting degradation rates of natural dissolved organic carbon by deep-sea prokaryotes under stratified water masses and deep-water convection conditions in the NW Mediterranean Sea

Most of the ocean is deep with majority its volume (> 80%) lying under a depth greater than 1000 m. Deep-ocean substrates input mainly supplied as organic matter (in particulate and/or dissolved forms) by physical and biological processes. Bioavailable carbon (DOC) consumed in surface water prokaryotes, while most DOC recalcitrant. Deep-sea prokaryotes are known to be adapted degrade complex substrates. In this study, we investigate utilization HMW-DOC on short temporal scale (10–15 days) deep-sea maintained at situ high-pressure conditions. prokaryotic natural assemblages were collected Mediterranean Sea two contrasting hydrological conditions (water column stratification deep-water formation period conditions). The experimental results coupled cell-quota model, order quantify kinetics degradation impact these show that stratified autochthonous able up 46.6% timescales incubation, when sampling By contrast, during convection condition, weakly degraded incubation This study shows remineralization rates controlled communities, which further driven column.