Algal identification using in vivo fluorescence spectra

Replicate excitation spectra of the fluorescence emission at 680 nm from 30 cultures of freshwater algae have been compared to determine the most sensitive regions for the differentiation of algal species. Spectra were normalized in four different ways prior to analysis in order to simulate different experimental approaches. The ratio of the fluorescence intensity in two wavelength bands, 360–390 and 510–580, relative to the intensity in the range 435–460 nm was found to be the most discriminating for the minimum effort. However, fluorescence per cell may give extra information and can be used by itself to distinguish blue-green algae from other classes.