Colimitation by light, nitrate, and iron in the Beaufort Sea in late summer

[1] As part of the GEOTRACES International Polar Year program, in September 2009 we performed a grow-out experiment to investigate the potential for nitrate, light, and iron (Fe) limitation of Beaufort Sea phytoplankton. Nutrients, phytoplankton biomass/composition, and Fe and C uptake rates were measured regularly. Nitrate additions enhanced phytoplankton growth, demonstrating that the late summer phytoplankton community was N limited. In the...