IngentaConnect Using absorbance and fluorescence spectra to discriminate microal...

Abstract:

The utility of absorbance and fluorescence-emission spectra for discriminating among microalgal phylogenetic groups, selected species, and phycobilin- and non-phycobilin-containing algae was examined using laboratory cultures. A similarity index algorithm, in conjunction with fourth-derivative transformation of absorbance spectra, provided discrimination among the chlorophyll [Chl] a/phycobilin (cyanobacteria), Chl a/Chl c/phycobilin (cryptophytes), Chl a/Chl b (chlorophytes, euglenophytes, prasinophytes), Chl a/Chl c/fucoxanthin (diatoms, chrysophytes, raphidophytes) and Chl a/Chl c/peridinin (dinoflagellates) spectral classes, and often between}among closely related phylogenetic groups within a class. Spectra for phylogenetic groups within the Chl a/Chl c/fucoxanthin, Chl a/Chl c/peridinin, Chl a/phycobilins and Chl a/Chl c/phycobilin classes were most distinguishable from spectra for groups within the Chl a/Chl b spectral class. Chrysophytes/diatoms/raphidophytes and dinoflagellates (groups within the comparable spectral classes, Chl a/Chl c/fucoxanthin and Chl a/Chl c/peridinin, respectively) displayed the greatest similarity between/among groups. Spectra for phylogenetic groups within the Chl a/Chl c classes displayed limited similarity with spectra for groups within the Chl/phycobilin classes. Among the cyanobacteria and chlorophytes surveyed, absorbance spectra of species possessing dissimilar cell morphologies were discriminated, with the greatest range of differentiation occurring among cyanobacteria. Among the cyanobacteria, spectra for selected problematic species were easily discriminated from spectra from each other and from other cyanobacteria. Fluorescence-emission spectra were distinct among spectral classes and the similarity comparisons involving fourth-derivative transformation of spectra discriminated the increasing contribution of distinct cyanobacterial species and between phycobilin- and non-phycobilin-containing species within a hypothetical mixed assemblage. These results were used to elucidate the application for in situ moored instrumentation incorporating such approaches in water quality monitoring programmes, particularly those targeting problematic cyanobacterial blooms.

Keywords: absorbance; algal monitoring; fluorescence; fourth-derivative analysis; similarity indices

Document Type: Research article

DOI: 10.1017/S0967026202003700

Affiliations: 1: Agricultural Research Service, US Department of Agriculture, c/o Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA 2: Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08903, USA 3: Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota FL 34240, USA 4: Trondheim Biological Station, University of Trondheim, The Museum, Bynesveien 46, 7018 Trondheim, Norway 5: Agricultural Research Service, US Department of Agriculture, 1100 Robert E. Lee Boulevard, New Orleans, LA 70124, USA

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Using absorbance and fluorescence spectra to discriminate microalgae