Respiration Rates in the Global Mesopelagic Ocean

Abstract Respiration in the mesopelagic layer of the oceans (200–1,000 dbar) is a key factor controlling the biological carbon pump, as it attenuates the downward flux of organic carbon to the ocean interior. Using a global data set of dissolved oxygen and transient tracer gas measurements, we report spatially resolved oxygen utilization rates (OUR) across 34 water masses of the global mesopelagic ocean. We find that OURs ranged between 0.6 and 27.3 μmol kg −1 yr −1 , varying both within and across water masses. Two main patterns emerge from our analysis: (a) OURs in central water masses (150–500 dbar) shared patterns with downward organic carbon flux proxies, and (b) OURs in intermediate and deep water masses (500–1,500 dbar) were overall consistent with basin‐scale circulation and aging patterns. These findings will help to constrain and parameterize mesopelagic respiration rates, a key component of global biogeochemical models.