Assessment of in situ fluorometry to measure cyanobacterial presence in water bodies with diverse cyanobacterial populations

• Good correlations found between phycocyanin (CPC) measurements and biovolume in 2 of 3 ponds.
• Poor correlation in the third was due to an abundance of picoplanktonic cyanobacteria.
• CPC measurements varied according to the dominant cyanobacteria in the ponds.
• In situ CPC measurements did not correlate well with cyanobacterial cell counts.
• In situ chlorophyll-a fluorescence was a poor measure of cyanobacterial biovolume.