Abstract: | Primuline staining is widely used to visualize and enumerate dinoflagellate cysts in marine sediments. In staining cysts of Gymnodinium catenatum H. W. Graham, Scrippsiella trochoidea (F. Stein) A. R. Loebl., and cysts from estuarine sediments, we found their green fluorescence after primuline treatment to be seemingly no different from the green autofluorescence (GAF) inherent in vegetative cells and cysts of dinoflagellates fixed in formaldehyde. Although primuline subsequently proved to enhance green fluorescence of both species quantitatively, we nonetheless recommend taking advantage of dinoflagellates' GAF to detect and count their cysts in sediments. Doing so will reduce the time, chemical consumption, and possible loss of cells involved in the primuline‐staining procedure. |