Figure 3.

Distribution of NO₃⁻ and the detected nifH clusters: NO₃⁻ (μM), nifH clusters P1, P4, P8 and Crocosphaera (log₁₀ copies l⁻¹), the oxycline (μM O₂) is indicated with brown contour lines along (left) 10°S and (right) 16°S as marked A and B on the map (Figure 1).