2.2. Cell counts
Cell counts and cell specific chlorophyll autofluorescence were measured using a BD Accuri C6 flow cytometer. Culture samples were diluted (100 μL culture in 900 μL medium) and passed through 30 μm filters to remove debris. Flow cytometry was carried out at a flow rate of 35 μL min− 1 and a core size of 16 μm. Phaeodactylum cells were quantified after gating from forward scatter and relative fluorescence emission (excitation at 488 nm, emission detection at > 670 nm).