Prorocentrum minimum culturing: All cultures were maintained routinely in F/2-Si in 32 PSU seawater, at 18C and 14:10 light:dark cycle at 50 uE (u = micro). All cultures were transferred once every two weeks.

At each time point, 2 ml of cells were removed from experimental culture flasks and preserved with gluteraldehyde (1% final concentration) and stored at 4C until used to make microscopy slides. To make slides, 1 ml of preserved sample was filtered onto a black 2 um nucleopore polycarbonate filter, and then mounted on a glass microscope slide with fluorescence grade immersion oil. Slides were then counted using fluorescence microscopy and stored at -20C.

Culturing and experimental methods can be found in Johnson 2015.