A compilation of photosynthesis-irradiance measurements from the Ross Sea, Antarctica, was analyzed for spatial and temporal trends, as well as the oceanographic factors that control the responses. The maximum, chlorophyll-specific, irradiance-saturated rate averaged 1.07+/-0.060 ug C per ug Chl per hour. Spring rates were 59% greater than summer rates. Irradiance, CO2, and iron had significant effects on rates. The effects of time need to be incorporated into models of Antarctic production.