The dark portion of the Mediterranean Sea is a bioreactor of organic matter cycling

摘要: [1] Total prokaryotic abundance, heterotrophic production and enzymatic activities were investigated in epi-, meso- bathypelagic waters along a longitudinal transect covering the entire Mediterranean Sea. The deep among highest reported worldwide at similar depths, indicating that peculiar physico-chemical characteristics of Sea, characterized by warm temperatures (typically 13°C also abyssal depths), support high rates organic carbon degradation incorporation assemblages. higher trophic conditions epipelagic Western basin resulted significantly than Central-Eastern basin. While all variables decreased from epi- to waters, cell-specific hydrolytic activity increased. In addition, deep-water layers low half-saturation constants (Km) activities. These findings suggest assemblages inhabiting dark portion Sea are able channel degraded into biomass very efficient way, work as “bioreactor” matter cycling. Since water masses inversely related with oxygen concentration, we hypothesize tight link between metabolism consumption. As climate change is increasing temperatures, predicted positive response temperature increases may accelerate depletion cascade consequences on cycling biogeochemical processes