Performance evaluation of phycocyanin probes for the monitoring of cyanobacteria

Abstract

The performance of two field probes (YSI 6600 and TriOS), used for the measurement of in vivo phycocyanin fluorescence, was compared and validated in the laboratory in 2008 and 2009 with cultures of Microcystis aeruginosa and field samples. The background noise of the two probes was low and the detection limits were estimated at 1500 cells mL(-1) for the YSI and 0.69 µg PC L(-1) for the TriOS. The linearity and repeatability of both probes have been excellent. Strong relationships were observed between the in vivo fluorescence and the total cyanobacterial biovolume (R(2) = 0.82 YSI; 0.83 TriOS) or the abundance (R(2) = 0.71 YSI; 0.75 TriOS) of cyanobacteria. However, the difference between cell densities determined by microscopy and measured by the YSI can be very large and has been associated to the variability of cell volume among cyanobacteria. This last observation makes the YSI a qualitative tool if a post-calibration is not done. The analysis of filtrated samples showed that dissolved phycocyanin (extracellular) may represent a significant fluorescence signal. No relationship could be established between the abundance, the total cyanobacterial biovolume or the in vivo fluorescence of phycocyanin and the concentrations of cyanotoxins (R(2) ≤ 0.22).

Cyanobacterial and microcystins dynamics following the application of hydrogen peroxide to waste stabilisation ponds

“…Upon cyanobacterial cell lysis following H 2 O 2 treatment, the pigment phycocyanin may be released to the extracellular, dissolved state. Recent work suggests that the release of phycocyanin may increase the apparent concentration of cyanobacterial chl a when measured using spectrofluorometry (Bastien et al, 2011;Moldaenke, 2009).…”

Alternative Methods for Analysis of Cyanobacterial Populations in Drinking Water Supplies: Fluorometric and Toxicological Applications Using Phycocyanin

“…We hoped to employ extracellular PC as a surrogate metric for extracellular microcystins where it could have been used within a screening protocol for water supply applications. The previous study [37] was an effort to quantify error associated with extracellular PC and the influence on the interpretation of in-vivo fluorometric applications. Given the averages from both studies (23% -24%) and the range of the observed values, the error could be significant.…”

An Adaptive Model to Monitor Chlorophyll-a in Inland Waters in Southern Quebec Using Downscaled MODIS Imagery

“…Moreover, the validation data were provided in cyanobacteria density units, which had to be converted to Chl-a units using the WHO conversion factor of 1 µg Chl-a to 2 million cells given in Chorus and Bartram [32]. Of course, the actual conversion factor can vary extensively with cell size and light history, and depends on the dominant species of a bloom [47,48]. This conversion thus introduced varying levels of uncertainty into the validation database.…”