Extensive prokaryotic maintenance respiration in the sea influenced by osmoregulation

Microbial respiration is the major process consuming oxygen in biosphere. The relative energy demand from growth of biomass or maintenance activities determines regulation with impact on how development hypoxia and CO 2 emissions controlled. This coupling crucial for understanding life history associated ecological interactions microorganisms. However, knowledge rate regulating factors biosphere limited. In this study, we demonstrated significant relationships marine field samples where prokaryotic specific predicts cell-specific respiration, accordance theory culture models, over a 10-fold salinity range. enables first reported direct estimates nature to show 6-fold variation between 0.12-0.62 fmol O cell -1 d , comprising 29-72% respiration. lowest occurred at close physiological osmolarity, suggesting osmoregulation as one more energy-consuming activities. A conservative global estimate accounted 66% total ocean´s mixed layer. means that dominate use generated by sea, consumer. Consequently, its must be included biogeochemical models accurately project manage ocean.