Measurement of cyanobacteria using in-vivo fluoroscopy – Effect of cyanobacterial species, pigments, and colonies

The effect of instrument calibration range, algal growth phase, chlorophyll-a and turbidity interference and colony size, on the measurement of phycocyanin by in-vivo fluoroscopy (IVF) was investigated. The cyanobacterial species Microcystis aeruginosa PCC 7820, Anabaena circinalis and Planktothricoides raciborskii were used to investigate variation in phycocyanin content in the different cyanobacteria and growth phases. The green alga, Chodatella sp., and Kaolin particles were used as the sources of chlorophyll-a and turbidity respectively to determine how these factors can impact on phycocyanin measurements. Another cyanobacterium, M. aeruginosa PCC 7005, which forms large colonies, was used to investigate the relationships between colony size and phycocyanin concentration measured using IVF. Results showed that chlorophyll-a, turbidity, and the colonial status of the cyanobacteria significantly interfered with the measurement of phycocyanin fluorescence. Models were developed to compensate for the effect of chlorophyll-a, turbidity and colony size on the measurement. The models were successfully used to correct phycocyanin probe data collected from several reservoirs in Taiwan to establish good correlation between measurements made using the phycocyanin probe and microscopic cell counts.

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► Measurement of phycocyanin using in-vivo fluoroscopy is examined.
► Chlorophyll-a, turbidity, and colonial cyanobacteria strongly interfered with the measurement.
► Models were developed to compensate for the interference.
► The models successfully simulated cyanobacteria concentrations in different reservoirs.
► For the first time impact of colony on fluorescence measurement of cyanobacteria was quantified.