Fig. 2: Physical and biogeochemical characterization of the surface South Pacific transect.
From: Patterns of (micro)nutrient limitation across the South Pacific Ocean
a Physical and chemical parameters including sea surface temperature (SST), dust deposition, dissolved Fe (DFe), dissolved manganese (DMn), dissolved aluminum (DAl), turbulent DFe supply, nitrate and phosphate concentrations. The light lines are the original data, while the bold lines are smoothed with a 5-point moving average. Sampling locations are highlighted with red inverted triangles and filled triangles indicate concentrations measured at experiment start points. b Phytoplankton chlorophyll-a concentrations and size classes variations. The white line is the oligotrophic gyre threshold (here defined as chlorophyll-a ≤ 0.07 mg m−3). c Total picophytoplankton fluorescence (i.e., summed fluorescence of the three groups), and the relative contribution of Prochlorococcus, Synechococcus, and photosynthetic picoeukaryotes (PPE) fluorescence to total picophytoplankton fluorescence. d Photophysiological (Fv/Fm) response of phytoplankton to N, Fe, and N+Fe supply at each bioassay experiments site. Bar heights represent mean responses of the tropical biological replicates for each treatment. Asterisks indicate significant Fv/Fm changes over controls (ANOVA followed by Tukey’s post hoc test, α < 0.05). The black and blue lines respectively represent the magnitude of Fv/Fm drawdown and phytoplankton net growth rates following N supply.
