XVI International Botanical Congess
HPLC-derived measurements of photopigments has become popular for characterizing algal composition. Multiple regression initially was used to estimate pigment ratios and to assess the phylogenetic group contribution to chlorophyll biomass. However, because this approach assumes comparable cell pigment contents and ratios among taxa/groups, and derives >predicted= values for chlorophyll biomass, its validity has been questioned. A technique utilizing factor analysis and a steepest descent algorithm to optimize pigment ratios recently has become the preferred method for estimating phylogenetic group contributions. Using pigment signatures of microalgae from diverse freshwater, marine, and estuarine ecosystems, the utility of these approaches for estimating microalgal class abundances will be evaluated.