Continental shelf ecosystems support diverse phytoplankton communities responsible for large portions of global primary productivity. The South Atlantic Bight (SAB) is a wide continental shelf that has a natural iron gradient, and across this gradient, phytoplankton communities are hypothesized to engage in distinct metabolic strategies. To examine iron ecophysiology in this region diatoms (Cylindrotheca closterium) and coccolithophores (Gephyrocapsa oceanica and Gephyrocapsa huxleyi) were collected from the inner and outer SAB shelves and grown in culture under steady state high and low iron conditions, with an additional iron amendment treatment to simulate rapid iron resupply. Lineage specific differences were observed. The diatoms indicated the capacity to proliferate under both iron conditions likely due to a coordinated activation of photoprotective mechanisms. While the coccolithophores appeared to utilize metabolic strategies reflecting conditions of the shelf region they originated. These results may help explain observed community composition and bloom succession patterns in the SAB.