[1] We describe a method for determining net annual biological oxygen production in the euphotic zone of the ocean using remote in situ measurements of oxygen and nitrogen gas. Temperature, salinity, oxygen, and total dissolved gas pressure were measured every 2 hours at 10-m depth on a mooring at the Hawaii Ocean time series during the year 2005. Since dissolved N2 is effectively inert to biol...

Despite the recently discovered importance of heterotrophic microorganisms in the structure and function of marine planktonic systems, little is known about the relative significance of these organisms in open-ocean oligotrophic environments. Here we report that depth profiles of planktonic nonphotosynthetic bacteria (BACT), cyanobacteria (CYANO), and both photosynthetic (PNAN) and heterotrophi...

Ammonia-oxidizing microorganisms compete with phytoplankton for reduced nitrogen in the euphotic zone and provide oxidized nitrogen to other microbes present in the sea. We report 15NH z4 oxidation rate measurements made at 5–20-m resolution using an in situ array and quantification of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in corresponding samples from the upper w...

Using an expanding Southern Ocean fleet of biogeochemical Argo (BGC-Argo) floats, we developed a novel approach to estimate annual net community production (ANCP) by integrating subsurface oxygen drawdown from all available BGC-Argo profiles. Our results suggest that, on average, 14% remineralization occurs between 500 and 1,000 m 15% the euphotic depth 100 m. improved methodology, estimated to...

In the subtropical gyres, phytoplankton rely on eddies for transporting nutrients from depth to euphotic zone. But, what controls rate of nutrient supply new production? We show that vertical flux both depends motion within eddying flow and varies nonlinearly with growth rate. Flux is maximized when matches inverse decorrelation timescale motion. Using a three-dimensional ocean model linear upt...

[1] The allochthonous supply of dissolved organic nitrogen (DON) from gyre margins into the interior of the ocean’s oligotrophic subtropical gyres potentially provides an important source of new N to gyre surface waters, thus sustaining export production. This process requires that a fraction of the transported DON be available to euphotic zone photoautotroph communities via mineralization. In ...

Sediment trap, nephelometer, and particulate matter (PM) data were collected in the vicinity of the Subtropical Convergence, north of Chatham Rise (42-43”S), southwest Pacific Ocean, in austral autumn 1992. Free-floating cylindrical sediment traps were deployed below the euphotic zone at 200-, 300-, and 500-m water depths. Increases in total mass flux and concomitant proportional decreases in o...

Ammonium (NH4+) dynamics in the oligotrophic South China Sea (SCS) were examined using data collected during summer 2014 and spring 2016. A sensitive fluorometric technique was used to measure NH4+ concentrations (detection limit of 0.7 nmol L−1). The inventory upper 100 m showed considerable variation between two samplings, averaging 3.46 mmol m−2 almost doubling This could be attributed seaso...

The ability to forecast the biological productivity of coastal ocean relies on quantification physical processes that deliver nutrients euphotic zone. Here we explore these pathways using observations coupled and variability waters offshore east coast Tasmania in summertime. include an array moored autonomous profilers deployed over 18-d period—providing continuous, full-depth measurements turb...