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ARS Home » Southeast Area » Auburn, Alabama » Aquatic Animal Health Research » Research » Publications at this Location » Publication #428072
Research Project: Improving Warmwater Finfish Health through Pathogen Characterization, Vaccination, and Natural Feed Additives

Location: Aquatic Animal Health Research

Title: A handheld fluorometer evaluates freshwater cyanobacterial blooms across a broad productivity gradient

Author
item LE, VE - Auburn University
item WILSON, ALAN - Auburn University

Submitted to: Lake and Reservoir Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2025
Publication Date: 5/26/2025
Citation: Le, V.V., Wilson, A.E. 2025. A handheld fluorometer evaluates freshwater cyanobacterial blooms across a broad productivity gradient. Lake and Reservoir Management. 41(2):104-111. https://doi.org/10.1080/10402381.2025.2484690.
DOI: https://doi.org/10.1080/10402381.2025.2484690

Interpretive Summary: The development of detection methods that can quickly and accurately monitor harmful algal blooms (HABs) is crucial for gaining sufficient response time to mitigate HAB impacts. This study aims to build on past evaluations of the Turner Designs CyanoFluor, a portable fluorometer, for monitoring freshwater HABs in the field. From 2017 to 2020, 1,043 water samples were collected from a variety of sources, including ultraoligotrophic drinking water reservoirs to hypereutrophic aquaculture ponds. Water samples were measured live for raw fluorescence (RFU) of chlorophyll-a (Chl-a) and phycocyanin (PC) using the CyanoFluor, in addition to being collected on filters for conventional fluorometric measurements for Chl-a and PC. After removing CyanoFluor measurements that exceeded saturation (>50,000 RFU), the remaining 880 samples showed that Chl-a measured by CyanoFluor and by a standard extraction method exhibited a strong linear, positive relationship (R2 = 0.855, P'<'0.00001, n'='880). Similarly, a significant positive relationship was observed between fluorometer PC RFUs and extracted PC concentrations (R2 = 0.664, P'<'0.00001, n'='713). Overall, our study supports that CyanoFluor is a useful and efficient instrument for measuring chlorophyll (all phytoplankton) and phycocyanin (cyanobacteria) in diverse freshwater systems, given that raw fluorescence measurements are strongly associated with standard extracted measurements that are used as indicators to monitor HABs.

Technical Abstract: The development of detection methods that can quickly and accurately monitor harmful algal blooms (HABs) is crucial for gaining sufficient response time to mitigate HAB impacts. This study aims to build on past evaluations of the Turner Designs CyanoFluor, a portable fluorometer, for monitoring freshwater HABs in the field. From 2017 to 2020, 1,043 water samples were collected from a variety of sources, including ultraoligotrophic drinking water reservoirs to hypereutrophic aquaculture ponds. Water samples were measured live for raw fluorescence (RFU) of chlorophyll-a (Chl-a) and phycocyanin (PC) using the CyanoFluor, in addition to being collected on filters for conventional fluorometric measurements for Chl-a and PC. After removing CyanoFluor measurements that exceeded saturation (>50,000 RFU), the remaining 880 samples showed that Chl-a measured by CyanoFluor and by a standard extraction method exhibited a strong linear, positive relationship (R2 = 0.855, P'<'0.00001, n'='880). Similarly, a significant positive relationship was observed between fluorometer PC RFUs and extracted PC concentrations (R2 = 0.664, P'<'0.00001, n'='713). Overall, our study supports that CyanoFluor is a useful and efficient instrument for measuring chlorophyll (all phytoplankton) and phycocyanin (cyanobacteria) in diverse freshwater systems, given that raw fluorescence measurements are strongly associated with standard extracted measurements that are used as indicators to monitor HABs.