Resource availability sets an upper limit to potential primary production, whereas autotroph diversity constrains how much of this is realized (Cardinale et al., 2009; Hillebrand 2014; Lewandowska 2016). On one side, phytoplankton biomass constrained by nutrient concentrations and the ratios in which limiting nutrients are available (balanced or imbalanced; Elser 2007; Harpole 2011). At balance...