An evaluation of algal enumeration

The data presented here can be used by water utility personnel who use the Palmer–Maloney method to approximate the standard deviation of their algal counts relative to the observed cell density. The Palmer–Maloney (P–M) counting chamber method, as described in Standard Methods section 10200‐F.2b, was used to enumerate 10 different unialgal cultures representing three algal morphologic types (i.e., colonial, unicellular, and filamentous). The standard deviations of counts obtained by the P–M method were not constant. Although the absolute standard deviation increased with increasing cell density, the relative standard deviation decreased from >30 percent at low cell density to <10 percent at high cell density. Variability among the three morphological types was similar.