Photosynthetic rates of marine algae as a function of inorganic carbon concentration

The effect of inorganic carbon concentration on the rates of carbon fixation by mixed phytoplankton and by three algal species in culture was examined. The inorganic carbon concentrations resulting in half‐maximal fixation rates ranged from 4.3–5.3 mg C · liter−1 for phytoplankton and from 0.8–3.0 for the axenic algal cultures. The applicability of the Michaelis‐Menten equation to experimental systems of n species is demonstrated.