In situ Quantification of Phytoplankton in Reservoirs Using a Submersible Spectrofluorometer

Abstract

A submersible in situ spectrofluorometer, which permits the differentiation of four algal groups (green algae, diatoms, cryptophytes and cyanobacteria), was used for phytoplankton monitoring in five reservoirs with varying levels of eutrophication and composition of their phytoplankton communities. Data obtained in situ were compared to standard laboratory methods for phytoplankton quantification; concentration of chlorophyll a and microscopy analysis. A high correlation (r = 0.95, n = 96) between chlorophyll a levels using different methods was found in all types of phytoplankton community. Taxonomic analyses and cell counts were closely related to the ratio of algal classes measured by the in situ spectrofluorometer. The submersible device used in the study measures in a continuous mode, which is advantageous in comparison with discrete sampling. This method appears to be a good tool for water quality management and can be used in the detection of natural horizontal and vertical variability in phytoplankton communities or for the early detection of cyanobacterial blooms. The device used in this study is recommended as a screening tool that enables more effective sampling that can be focused on the localities and depths where changes in phytoplankton composition occur.Abbreviations: Chl a -chlorophyll a; FP -FluoroProbe; LED -light emitting diode

Comparison of cyanobacteria monitoring methods in a tropical reservoir by in vivo and in situ spectrofluorometry

“…According to MacIntyre et al (2010), to compensate nutrient limitation at the peak moment, cyanobacteria may change their photosynthetic apparatus and increase fluorescence emission. Thus, during cyanobacteria peak growth stages, differences between FP and spectrophotometric chla concentration may be smaller (Gregor et al, 2005).…”

“…(2012) and Gregor et al (2005) argued that in case of high cyanobacteria dominance, FP could incorrectly assign cyanobacteria to the "Cryptophyta" group because of the presence of phycoerythrin in both cryptophytes and cyanobacteria cells. Even if no phycoerythrincontaining cyanobacteria were observed, we disabled the Cryptophyta class in the FP software to avoid incorrectly assignment of some cyanobacteria.…”

“…The proportions between accessory pigments and chla result in an excitation spectrum, later called "fingerprint", specific for a taxonomical phytoplankton class (Dau, 1998;Huot and Babin, 2010). The ability of such a probe, the FluoroProbe (FP-BBE FluoroProbe, Moldaenke, Germany), to estimate phytoplankton biomass and taxonomic composition has been demonstrated in different water bodies, mainly in temperate climate regions (Catherine et al, 2012;Gregor et al, 2005;Gregor and Maršálek, 2004;Rolland et al, 2010). This probe has been used to study the temporal variability in marine phytoplankton photosynthetic activity (Houliez et al, 2015), the impact of the resuspension of contaminated sediment on phytoplankton (Lafabrie et al, 2013), the influence of microscale turbulence on coastal phytoplankton (Machado et al, 2014), the relationships between toxin and cyanobacteria concentrations in lakes and reservoirs (Salmaso et al, 2014).…”

“…Although total chla given by FP and laboratory spectrophotometry are generally correlated, FP values are frequently underestimated and different degrees of underestimation were observed (see Catherine et al, 2012;Gregor and Maršálek, 2004;Gregor et al, 2005;Leboulanger et al, 2002). Another controversial issue is the upper measuring limit of the probe.…”

Validação do método de Sedgwick-Rafter para a quantificação do fitoplâncton

“…Para a quantificação do fitoplâncton há métodos microscópicos (BRANCO, 1986;LAWTON et al, 1999 MCDERMOTT, 2010;EDLER;ELBRÄCHTER, 2010) e métodos moleculares (GALLUZZI;PENNA, 2010;GESCHER;MARRIN III;SCHOLIN, 2010;DIERCKS;. Além destes, há métodos que utilizam fluorescência (BEUTLER et al, 2002;LEBOULANGER et al, 2002;MARŠÁLEK, 2004;GREGOR et al, 2005) e contagem de partículas (SIERACKI; SIERACKI; YENTSCH, 1998;DUBELAAR et al, 1999;DUBELAAR;GERRITZEN, 2000;SHALAPYONOK;OLSON, 2007;THYSSEN et al, 2008).…”