PARENT SESSION
Posters P2D Marine photosynthesis and production. Abstracts (711-719)

Iron regulation of marine phytoplankton photosynthesis: Theory and observations. Zackary Johnson^*,1, Michael Hiscock², Richard Barber², ¹ Civil and Environmental Engineering, Cambridge, MA, USA² Marine Laboratory, Duke University, Beaufort, NC, USA

ABSTRACT- Iron supply plays an important regulatory role in phytoplankton primary production in certain ocean regions and laboratory work has shown that iron regulates photosynthetic physiology by altering photosynthetic electron transport. However, iron-specific physiological parameters of photosynthesis have not been quantitatively related to observed phytoplankton photosynthetic responses under iron-replete and iron-limited conditions, in part because there is no analytical theory that explicitly links the parameters and response. Here we present such an analytical theory that employs iron-dependent parameters of photosynthetic performance to independently describe the photosynthesis vs. irradiance (Pb vs E) response in terms of light absorption and photosynthetic electron transport. This model reproduces with considerable fidelity the Pb vs E responses observed during two in situ iron addition experiments: one in the equatorial Pacific Ocean (IRONEX) and one in the Southern Ocean (SOFEX). These results suggest that the carbon uptake responses of ambient phytoplankton communities to iron addition can be predicted if the mechanistic parameters of photosynthesis are quantified.

KEY WORDS: model, marine, iron, phytoplankton