Mean and standard deviation of bacterial productivity by day 4 of the incubation experiments are shown for triplicate incubations of Fe additions (dark bars) and unamended controls (white bars). Rates are shown for surface (S) and deeper subsurface (D) incubations from Stations 5, 13, and 35 (A) and for different levels of incident irradiance (1%, black; 10%, grey; 50%, light grey) for Stations 57 and 66 (B).