Abstract details
A fluorometric method for the differentiation of algal populations in vivo and in situ
Photosynthesis Research 72: 3953, 2002. © 2002 Kluwer Academic Publishers. Printed in the Netherlands. Regular paper
M. Beutler 1,2,., K. H.Wiltshire 3, B.Meyer 2, C. Moldaenke 4, C. Lüring4, M. Meyerhöfer 5, U.-P. Hansen1 & H. Dau 6 1 Zentrum für Biochemie und Molekularbiologie (ZBM), Universität Kiel, Leibnizstr. 11, 24098 Kiel, Germany; 2 Max-Planck-Institut (MPI) für Limnologie, August-Thienemann-Strasse 2, 24302 Plön, Germany; 3 Biologische Anstalt Helgoland, Awi, Postfach 180, 27483 Helgoland, Germany; 4 bbe Moldaenke, Wildrosenweg 3, 24119 Kiel-Kronshagen, Germany; 5 Institut für Meereskunde (IfM), Düsternbrooker Weg 20, 24105 Kiel, Germany; 6 Freie Universität Berlin, FB Physik, Arnimallee 14, 14195 Berlin, Germany.Received 21 March 2001; accepted in revised form 25 January 2002 Abstract
Fingerprints of excitation spectra of chlorophyll (Chl) fluorescence can be used to differentiate 'spectral groups' of microalgae in vivo and in situ in, for example, vertical profiles within a few seconds. The investigated spectral groups of algae (green group, Chlorophyta; blue-green algae and brown algae, Heterokontophyta, Haptophyta, Dinophyta;mixed, Cryptophyta) are each characterised by a specific composition of photosynthetic antenna pigments and, consequently, by a specific excitation spectrum of the Chl fluorescence. Particularly relevant are Chl a, Chl c, phycocyanobilin, phycoerythrobilin, fucoxanthin and peridinin. A laboratory-based instrument and a submersible instrument were constructed containing light-emitting diodes to excite Chl fluorescence in five distinct wavelength ranges. Norm spectra were determined for the four spectral algal groups (several species per group). Using these norm spectra and the actual five-point excitation spectrum of a water sample, a separate estimate of the respective Chl concentration is rapidly obtained for each algal group. The results of dilution experiments are presented. In vivo and in situ measurements are compared with results obtained by HPLC analysis. Depth profiles of the distribution of spectral algal groups taken over a time period of few seconds are shown. The method for algae differentiation described here opens up new research areas, monitoring and supervision tasks related to photosynthetic primary production in aquatic environments. Key words: accessory pigments, aquatic ecosystems, chlorophyll fluorescence, phytoplankton, primary production
