Fig. 5.

Utility of environmental context to define the present physiological status of cells in relation to prior oceanic conditions. (A) Dissolved Fe time series for the upper ocean in the subtropical Atlantic (BATS site) that reveals conspicuous aerosol Fe inputs (>0.5 nmol L⁻¹) along with the influence of eddy activity (<0.3 nmol L⁻¹) on dissolved Fe concentrations (Sedwick et al., 2020). (B) Photosynthetic efficiency of PSII (F_v/F_m) measured in deckboard incubation experiments “titrated” with dissolved Fe concentrations by either lowering bioavailable Fe using the fungal siderophore desferrioxamine B (DFB) or increasing it with chelated inorganic Fe addition (from Wilhelm et al., 2013). The circles denote putative linkages between chemical stocks and biological responses (blue = high Fe; green = low Fe).