Fig. 2.

Macronutrient ($\mathrm{\mu }$mol$\cdot$L⁻¹), size-fractionated chlorophyll a ($\mathrm{\mu }$g$\cdot$L⁻¹), and biogenic silica ($\mathrm{\mu }$mol$\cdot$L⁻¹) concentrations and maximum photochemical yields of photosystem II (F_v:F_m) from the initial collected seawater (t = 0) and incubations at various time points. Incubations are labeled as follows: control (C), iron addition (Fe), iron removal (DFB), and iron addition followed by removal (FeDFB) and denoted as the first or second time point (T₁ or T₂) where applicable. CUZ sites and Line-P sites are grouped separately as two of the x-axis scales are different.