Model-derived Estimates of Primary Production and Carbon Flux in the Ross Sea

Hae-Cheol Kim, Walker O. Smith, Jr., Eileen E. Hofmann, and Michael S. Dinniman

A bio-optical production model that included simulated surface irradiance (corrected for cloud conditions) and the underwater light field was used to estimate primary production and subsequent carbon flux throughout the Ross Sea. The net change in production through time was estimated from carbon budgets that included the effects of grazing, zonal advection, and sinking. Calculations on zonal advection suggest it is the dominant process controlling phytoplankton standing stocks in the outer-shelf regions in all seasons, with up to 57% of the carbon being advected from this zone. Grazing is relatively unimportant in all regions, with the maximum impact (removing 5.2% of primary production) being observed in the mid-shelf region during summer. Passive vertical sinking is an important process for carbon flux, especially in the inner shelf zone. Up to 20% of the daily primary production is removed by passive sinking during summer. The relative roles of each process may explain the spatial variations in biomass observed during the annual growth cycle. Comparisons with the west Antarctic Peninsula suggest that horizontal loss processes may be a quantitatively important loss term in a variety of Antarctic continental shelf systems with diverse physical forcing and ecology. Future changes in water-column horizontal flow that result from climate change will be quantitatively important in controlling biological production and accumulation.

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