Quantifying Particulate Organic Carbon Concentrations and Flux in the Southwestern Ross Sea Using Autonomous Glider Data

To assess biological and hydrographic features of the Southwestern Ross Sea through time, we deployed a glider in a spatially restricted area in the austral summer (Dec. 1 – Jan. 17) of 2012-2013. Using the high-resolution data, we quantified the particulate organic carbon concentrations and their changes through time. We also analyzed the dissolved oxygen concentrations throughout the upper 250 m. The austral summer in the southern Ross Sea can be divided into three distinct phases characterized by changes in surface POC concentrations and export. POC concentrations were initially < 100 mg m^-3, increased and exceeded 250 mg m^-3 at the bloom maximum and declined to 170 mg m^-3 by mid-January. From these data, we estimated rates of vertical flux and the rate coefficient of particulate organic carbon flux attenuation (Martin’s b value) by constructing a carbon balance for the water column. While the Ross Sea is known to be the site of substantial carbon fixation, there remains an incomplete understanding both of the processes involved in export and the rates (and controls) of remineralization; their variations in space and time are also poorly constrained. These temporal changes and variations in remineralization appear linked to shifts in the dominant surface phytoplankton composition and deviations from the expected oxygen utilization. Rapid changes in export on the event scale (e.g., via strong wind events) were also observed, and acted to redistribute POC in the surface layer and enhance sinking from the euphotic zone.