“…In calculating the elemental composition of bulk phytoplankton biomass, we assume fixed elemental compositions for protein, lipid, carbohydrate, and chlorophyll in terms of C, H, O, N, P (Table S1). Lipid is further split into two pools, two thirds to the P‐free lipid pool and one third to phospholipid (Finkel et al, ). We calculate C, H, O, N, and P content of the bulk organic matter (sum of all the macromolecules) and then compute RQ assuming complete aerobic oxidation of organic matter coupled with nitrification of ammonia to nitrate (Anderson, ): …”