Nitrate fixation. (a)Trichodesmium and (b) UCYN abundances (log nifH copies m^–2), (c) N₂ fixation rates (μmol N m^–2 d^–1), and (d) primary production rates (mmol C m^–2 d^–1), during the Pandora (austral winter, blue dots) and MoorSPICE (austral summer, red dots) cruises. All data are integrated over the 0–100 m layer, corresponding approximately to the photic zone. DOI: https://doi.org/10.1525/elementa.221.f9