For every cast with nutrient measurements at 2 or more pressures, we linearly interpolated nitrate and phosphate concentrations for every 1 dbar down to a maximum pressure of 1000 dbar. The interpolation only spanned between the lowest and highest pressures with nutrient measurements. Similarly, we interpolated temperature and salinity from the respective cruise CTD file for every 1 dbar. We then recorded the nutricline as the pressure and density where the interpolated nutrient concentrations first reached threshold concentrations. The nutricline pressure was converted to depth (m) using a UNESCO formula revised by Leroy & Parthiot (1998) (58).