Spectral fluorescence signatures in the characterization of phytoplankton community composition

Fluorescence spectral signatures from 28 algal cultures are described.The cultures are split into four groups according to their accessory pigments. Phycocyanin and phycoerythrin, characteristic pigments of cyanobacteria, form groups I and II. The characteristic pigment found in group III is chlorophyll b (green and rasinophyte algae) and in group IV it is chlorophyll c (diatoms, dinophytes and some other algae).This preliminary catalogue of spectral signatures was used to characterize five natural phytoplankton communities from brackish water environments as a comparison with phytoplankton species found in the samples. Accessory pigments such as phycocyanin and phycoerythrin, characterizing groups I and II, can be used for identification without confusion. Distinguishing between groups III and IV is more complicated, because their accessory pigments do not have their own fluorescence. These groups can be characterized by increased fluorescence of chlorophyll a induced by energy excited through chlorophyll b and c . The possibilities of applying the spectral fluorescence signatures approach to the characterization of natural communities are discussed.