Pigment analysis of benthic and pelagic algae in Lake Okeechobee, Florida

Water samples from Lake Okeechobee, Florida have been analyzed in order to relate pigment fingerprints to temporal and spatial variations. Chemical taxonomic identification of predominant photoautotrophs was based on pigment profiles evolved from literature reports and analysis of specific cultures. Carotenoids and chlorophylls were analyzed using high performance liquid chromatography (HPLC) and ultra-violet visible spectra obtained with a photo diode array detector (PDA). Pigments were identified by coincident matches of retention time and UV/Visible spectral properties. Chemical taxonomic identification was determined by comparison with known photoautotrophic pigment 'fingerprints'. Experimental results show pigment arrays indicative of chromophytes, chlorophytes and cyanophytes as well as photoautotrophic bacteria present in Lake Okeechobee. The lake was also found to be heterogeneous and dynamic in terms of pigment composition. Major pigment groups changed as a function of location in the lake and as a function of season. A greater pigment diversity was found to exist in the benthos due to the presence of degradation products. HPLC-PDA pigment analysis for chemotaxonomic typing of photoautotrophic communities is attainable and can be used as a rapid viable alternative to microscopic examination of plankton and epiphyte samples. Also, taxonomic typing of organic matter and photoautotrophic communities of sediments, including bacterial populations, can be accomplished using this method.