The use of DAPI for identifying and counting aquatic microflora1

Abstract

A highly specific and sensitive fluorescing DNA stain, 4′6‐diamidino‐2‐phenylindole (DAPI) was compared with acridine orange (AO) for counting aquatic microflora. Use of DAPI improved visualization and counting of <1‐ µ m bacteria and blue‐green algae in seston‐rich samples and extended sample storage to at least 24 weeks.