Fig. 2: Summary of observed euphotic zone nitrogen fluxes from the oligotrophic Gulf of Mexico.
From: Lateral advection supports nitrogen export in the oligotrophic open-ocean Gulf of Mexico
a Sediment trap fluxes include export at the base of the upper euphotic zone (UEZ) (open squares) and lower euphotic zone (LEZ; closed circles). b Zooplankton excretion below the euphotic zone. c Vertical mixing of nitrate into the LEZ. Mixing into UEZ not shown (~0). d N2-fixation rates modeled from observed Trichodesmium biomass (UEZ; circles) and from δ15N-based budgets for the entire euphotic zone (squares) as reported in Knapp et al15. Fluxes < 0.1 µmol N m−2 d−1 are shown on left as open symbols. Colors correspond to experiment as indicated with error bars indicating ± 1 SD of measurement means (a–c) or reported ranges (d).
