Using DCMU-fluorescence method for the identification of dominant phytoplankton groups

Abstract

For the identification of ecologically significant dominant groups of phytoplanktonic algae a polychromatic DCMUinduced fluorescence method is recommended. A special fluorometer equipped with a system of replaceable filters is used to differentiate three regions of the spectrum (410 ± 20, 510 ± 20 and 540 ± 10 nm) that can excite the basic light-harvesting pigments. Total and differential (for every algal taxon studied) chlorophyll a calculated from the fluorescence signals is in good agreement with biomass estimates from direct cell counts for several different trophic types of aquatic systems. This is made possible by the vizualization of the ratios of fluorescence signal values in their own coordinates: first, to decide whether it is necessary to correct linear equations in order to eliminate negative solutions; second, to determine the possibility of nulling the negative solution if a point is situated close to a side of the triangle; and third, to reduce the number of linear algebraic equations to two if the points are situated along one of the triangle sides or to one if the points are gathered at the apex. The polychromatic DCMU-induced fluorescence method can be used for monitoring natural phytoplankton populations to detect changes in their taxonomic structure.Abbreviations: DCMU, 3-(3,4-dichlorophenyl)-1,1-dimethylurea; DOM, dissolved organic matter

Estimation of periphytic microalgae gross primary production with DCMU-fluorescence method in Yenisei River (Siberia, Russia)

“…5), which allows us to make a conclusion about applicability of the DCMU-fluorescence method for estimation of gross primary production of stream periphyton (epilithon). The main advantages of this method were described elsewhere (Gaevsky et al 2005), but, briefly, in the first, in contrast to PAM-fluorescence, it is possible to determine chlorophyll a concentration and relative variable fluorescence when biomass of periphyton is high and Cyanophyta dominate. The second, using inhibitor of electron-transfer chain (DCMU), allows avoiding the effect of photosynthesis on the specific fluorescence yield and the obtaining of actual potential photosynthetic activity of microalgae and chlorophyll a concentration data.…”

“…The fluorometer was equipped with a system of replaceable filters (410±20, 510±20 and 540±10 nm) for differentiation of three groups of dominant algal taxons: (1) Chlorophyta and Euglenophyta, (2) Bacillariophyta and Dinophyta, and (3) Cyanophyta. Calculation of Chl a was carried out using the visualization method described in (Gaevsky et al 2005). Total Chl a concentration was calculated as the sum of Chl a of all three groups.…”

“…Pulse amplitudemodulated (PAM) fluorescence methods are used for estimation of biomass and photosynthetic activity of microalgae in oligotrophic lakes and oceans (Sakshaug et al 1997;Serodio 2004), but these methods have limitations under high algae biomass and Cyanophyta predominance (Ting and Owens 1992;Kromkamp et al 1998). Recently, it was shown that the DCMU-fluorescence method could be used successfully for determination of chlorophyll a concentration and primary production of plankton microalgae in mesotrophic and eutrophic water bodies (Gaevsky et al 2000(Gaevsky et al , 2002(Gaevsky et al , 2005.…”

Efficiency of transfer of essential polyunsaturated fatty acids versus organic carbon from producers to consumers in a eutrophic reservoir

“…1 was from Gaevsky et al (2005). The chlorophyll a concentrations, mg m -3 , of the algae groups were multiplied by the depth (4.5 m from May to July and 3.5 m to the end of September) of the reservoir for recalculations of the chlorophyll content by depth, mg m -2 .…”

Ecological development and genetic diversity of Microcystis aeruginosa from artificial reservoir in Russia

“…Fluorescence methods allow the identification of green algae, diatoms, and cyanobacteria in phytoplankton based on their differences in fluorescence excitation spectra (Gaevsky et al, 2005). Pigments from algae (chlorophylls a, b, c, carotenoids, including fucoxanthin, phycobilins, etc.)…”