Cost Effective Algae Control

Click here to read the OpFlow article.

by Frances Buerkens, Tricia Kilgore, Hunter Adams

Two utilities demonstrate a savvy approach focused on biological monitoring and management helps water utilities implement cost-effective algae control. One utility is based in Texas and the other is based in South Carolina. Phytoxigene’s CyanoDTec qPCR kits are deployed in public water utilities to monitor for toxins which are produced by some of the same organisms responsible for taste and odor events. Utilities often add CyanoDTec thanks to its relative ease of use and consistent results compared to toxin testing.

Free Sample Analysis: Send 2 Samples

GreenWater Laboratories (USA) and RPC (Canada) are partnering with Phytoxigene to offer free analysis of 2 raw water samples until May 31, 2026 to drinking water utilities and water managers. (New customers only, please.) The analysis being offered is in Standard Methods 10120 and includes detection of the genes responsible for the production of Microcystin, Cylindrospermopsin, Saxitoxin, and 16s (the gene common to all cyanobacteria).

Many of our customers have GreenWater Laboratories or RPC analyze samples on their behalf. Both laboratories bring a high degree of expertise and precision. We highly recommend them!

Instructions:

• USA based operations should send samples to GreenWater Laboratories: Sample Collection Instructions, Chain of Custody (*write “Phytoxigene free sample analysis program” in notes)

• Canadian based operations should send samples to RPC: Sample Submission Form. Sample Collection Instructions. (*write “Phytoxigene free sample analysis program” in notes)

• Raw water samples should be collected just below the surface.

• Collect 250 mL per sample in plastic containers with screw top lids.

• DO NOT FREEZE. Put samples on ice and ship the day of collection.

qPCR-based prediction of low-level microcystin-LR using mcyE and passive sampling across multiple lakes and years

David J. Redden, Clarke Brown, Morgan Harasymchuk, Saksham Bafna, Justin Laforest, Nicole Taylor, Lindsay E. Anderson, Graham A. Gagnon. Water Research X. 30 (2026) 100472 https://doi.org/10.1016/j.wroa.2025.100472

Abstract

Microcystin-LR (MC-LR) is a cyanobacterial hepatotoxin that poses health risks even at low concentrations. Because quantitative analysis of MC-LR is costly and time-consuming, water managers rely on early warning tools to determine when confirmatory testing is warranted. Quantitative PCR (qPCR) targeting the mcy genes has emerged as one such tool, but its reliability across lakes and seasons — particularly at low toxin concentrations — remains unclear. In this study, we used passive sampling to detect low concentrations (< 1 µg L− 1 ) of MC-LR and paired this with qPCR monitoring of mcyE to assess whether mcyE alone can serve as a reliable indicator of low-level MC-LR presence over three years across ten lakes (total of n = 893 distinct samples). We developed location- and year-specific hierarchical Bayesian models to estimate the probability of MC-LR detection from mcyE concentrations. We also included environmental covariates to determine if their inclusion improved model performance. Although mcyE was the strongest overall predictor, its relationship with MC-LR varied substantially by location and year, and these hierarchical models were essential in capturing this variability. These findings highlight the promise of mcyE-based early warning systems for low-concentrations of MC-LR but emphasize that interpretation must be tailored to local ecological and seasonal conditions.

Successfully Detecting and Mitigating Algal Blooms and Taste and Odor Compounds

Journal AWWA Cover Story for July/August 2021 Issue

Click here to read the article.

After receiving hundreds of complaints, the City of Wichita Falls, Texas, developed a plan for monitoring harmful algal blooms to detect and mitigate taste and odor (T&O) compounds and cyanotoxins.

The plan uses sensory analysis, genus-level or functional-group identification, gas chromatography–mass spectrometry/electron capture detector, data sondes, and quantitative polymerase chain reaction (qPCR) to monitor blooms for T&O issues and cyanotoxins before they become problems.

When blooms are detected, mitigation efforts include source-switching, pretreatment, oxidation, and adsorption, which have eliminated customer complaints following more than 60 years of unmitigated T&O cycles.

Hunter Adams,  Mark Southard,  Sam Sam Reeder,  Frances Buerkens,  Randal L. Hallford,  Keisuke Ikehata,  Daniel K. Nix

Peer Reviewed Paper Highlight for 2025

In addition to the Interlaboratory Study published in January, these two Phytoxigene customers published papers referencing their work using CyanoDTec.

Genomic Identification and Characterization of Saxitoxin Producing Cyanobacteria in Western Lake Erie Harmful Algal Blooms

The Saxitoxin gene target, sxtA (Phytoxigene-CyanoDTec)  was detected by quantitative polymerase chain reaction during 47 of 76 sampling dates between 2015 and 2019, demonstrating higher sensitivity than metagenomic approaches. sxtA gene abundance was positively correlated with temperature and particulate nitrogen:phosphorus ratio and negatively correlated with ammonium concentration.

Paul A. Den Uyl, E. Anders Kiledal, Reagan M. Errera, Subba Rao Chaganti, Casey M. Godwin, Heather A. Raymond, Gregory J. Dick. Environ.Sci.Technol.2025,59,7600−7612 https://doi.org/10.1021/acs.est.4c10888

Environmental factors driving microcystin contamination of estuarine bivalve populations downstream of freshwater cyanobacterial blooms

The CyanoDTec assay was used to characterize cyanobacteria blooms and microcystin production in freshwater tributaries feeding into estuaries in Long Island, New York.

Marcella Kretz Wallace, Raphael M. Kudela, Marine Pollution Bulletin Volume 214, May 2025 https://doi.org/10.1016/j.marpolbul.2025.117798

New Team Member: Frances Buerkens

Please welcome Frances Buerkens to Phytoxigene! Frances formerly worked with Yokogawa Fluid Imaging Technologies, promoting the FlowCam to drinking water utilities and monitoring agencies around the world. Now she’s wielding her HAB monitoring expertise to help organizations boost their HAB toxin screening and prediction programs.

Frances has an MBA in Operations Management and a BS in Agriculture and Natural Resource Management. Thanks to her agricultural background, she understands how water quality problems are created. She has long collaborated with customers around the world to monitor and manage source water, addressing concerns about the cyanobacteria and algae populations that proliferate largely because of agricultural runoff. 

The spatiotemporal distribution of potential saxitoxin-producing cyanobacteria in western Lake Erie

Callie Nauman, Keara Stanislawczyk, Laura A. Reitz, Justin D. Chaffin

Abstract

Cyanobacterial blooms in the western basin of Lake Erie have been well studied with a focus on planktonic Microcystis and the cyanotoxin microcystin, but recent research has shown that blooms are not entirely Microcystis. Previous studies have documented other taxa in blooms capable of producing other cyanotoxins. Furthermore, benthic cyanobacteria have historically been overlooked in Lake Erie. Saxitoxin is a cyanotoxin of emerging concern in freshwater, and the sxtA gene which encodes its production has been found in the Maumee River and central basin of Lake Erie. Collectively, these points indicated that saxitoxin-producing cyanobacteria may also occur in the western basin. We utilized three sources of data to determine the spatial and temporal distribution of potential saxitoxin-producing cyanobacteria in the water column (years 2018–2022) and deployed nutrient diffusing substrata (NDS) to determine the impact of nutrients, depth, and season on potential-STX producing benthic cyanobacteria (years 2018 & 2019). The water column datasets showed that “hotspots” of sxtA lasted only a few weeks. sxtA gene copies per mL did not correlate with Dolichospermum or Aphanizomenon biovolume, which have been associated with sxtA elsewhere. In the NDS, saxitoxin (ng/cm2) and cyanobacteria chlorophyll were inversely correlated with the highest saxitoxin in September and at the deeper depth, whereas cyanobacteria chlorophyll was highest during June and at the shallower depth. This research suggests continued monitoring is needed to determine drivers of saxitoxin in the western basin, and we recommend that future Lake Erie cyanobacteria research should not solely focus on microcystins and planktonic blooms.

Risk assessment of toxic cyanobacterial blooms in recreational waters: A comparative study of monitoring methods

Quirijn J.F. Schürmann a,c , Petra M. Visser a , Susan Sollie b , W. Edwin A. Kardinaal c , Elisabeth J. Faassen d,e

Click here to read the paper.

Quirijn J.F. Schürmann a,c , Petra M. Visser a , Susan Sollie b , W. Edwin A. Kardinaal c , Elisabeth J. Faassen d,e , Ridouan Lokmani f , Ron van der Oost g , Dedmer B. Van de Waal

Harmful Algae 138 (2024) 102683

Abstract

Toxic cyanobacterial blooms impose a health risk to recreational users, and monitoring of cyanobacteria and associated toxins is required to assess this risk. Traditionally, monitoring for risk assessment is based on cyanobacterial biomass, which assumes that all cyanobacteria potentially produce toxins. While these methods may be cost effective, relatively fast, and more widely accessible, they often lead to an overestimation of the health risk induced by cyanotoxins. Monitoring methods that more directly target toxins, or toxin producing genes, may provide a better risk assessment, yet these methods may be more costly, usually take longer, or are not widely accessible. In this study, we compared six monitoring methods (fluorometry, microscopy, qPCR of 16S and mcyE, ELISA assays, and LC-MS/MS), of which the last three focussed on the most abundant cyanotoxin microcystins, across 11 lakes in the Netherlands during the bathing water season (May-October) of 2019. Results of all monitoring methods significantly correlated with LC-MS/MS obtained microcystin levels (the assumed ‘golden standard’), with stronger correlations for methods targeting microcystins (ELISA) and microcystin genes (mcyE). The estimated risk levels differed substantially between methods, with 78 % and 56 % of alert level exceedances in the total number of collected samples for fluorometry and microscopy-based methods, respectively, while this was only 16 % and 6 % when the risk assessment was based on ELISA and LC-MS/MS obtained toxin concentrations, respectively. Integrating our results with earlier findings confirmed a strong association between microcystin concentration and the biovolume of potential microcystin-producing genera. Moreover, using an extended database consisting of 4265 observations from 461 locations across the Netherlands in the bathing water seasons of 2015 – 2019, we showed a strong association between fluorescence and the biovolume of potentially toxin-producing genera. Our results indicate that a two-tiered approach may be an effective risk assessment strategy, with first a biomass-based method (fluorometry, biovolume) until the first alert level is exceeded, after which the risk level can be confirmed or adjusted based on follow-up toxin or toxin gene analyses.

Microcystin contamination of estuarine bivalves downstream of freshwater cyanobacterial blooms

Click here to read the full paper.

Marcella Kretz Wallace, Raphael M. Kudela b Marine Pollution Bulletin Volume 214, May 2025

Abstract

Estuaries are dynamic environments that provide vital habitat to ecologically and commercially important bivalves. In some cases, freshwater tributaries can introduce cyanobacteria and associated cyanotoxins into estuaries that may subsequently accumulate in estuarine bivalves. Temporarily open/closed estuaries (TOCEs), which only experience tidal input for limited periods of time, may be particularly vulnerable to the accumulation of cyanotoxins in bivalves as they can be subject to freshwater input without tidal flushing and may experience lower salinities and cyanobacterial blooms. This study quantified levels of microcystin in bivalves collected as a time series over a five-year period (2017–2021) from Mecox Bay, a TOCE on Long Island, NY, USA, that hosts a productive oyster fishery and is downstream of a freshwater body that hosts microcystin-producing cyanobacterial blooms. During the study, microcystin was detected in all bivalves monitored including Eastern oysters (Crassostrea virginica), blue mussels (Mytilus edulis), and soft-shell clams (Mya arenaria), with levels in oysters exceeding those in other species and frequently exceeding 10 ng g−1, the California regulatory action level for microcystin in tissue. While oysters were capable of depurating 60–90 % of microcystin after four-to-six weeks during summer, microcystin loads in bivalves often peaked in cooler months after water column cyanobacteria and microcystin levels had seasonally declined, suggesting toxin depuration slowed at colder temperatures. Multiple linear regression models established that time-integrated measurements of pelagic microcystin concentrations in freshwater and estuarine locations, water temperature (inverse correlation), and salinity had highly significant (r2 = 0.71; p < 0.001) predictive power of the microcystin content in oysters. These findings demonstrate that bivalves, particularly oysters, in TOCEs located downstream of microcystin-producing cyanobacterial blooms are vulnerable to microcystin contamination, especially during fall months when temperature-dependent toxin depuration rates are likely slow.

On-Farm Workflow for Predictive Management of Paralytic Shellfish Toxin

Click here to read the paper….

Rendy Ruvindy, Penelope A. Ajani, Sereena Ashlin, Gustaaf Hallegraeff, Kerstin Klemm, Christopher J. Bolch, Sarah Ugalde, Mark Van Asten, Stephen Woodcock, Matthew Tesoriero, Shauna A. Murray*

Abstract

Paralytic shellfish toxins (PSTs) produced by marine dinoflagellates significantly impact shellfish industries worldwide. Early detection on-farm and with minimal training would allow additional time for management decisions to minimize economic losses. Here, we describe and test a standardized workflow based on the detection of sxtA4, an initial gene in the biosynthesis of PSTs. The workflow is simple and inexpensive and does not require a specialized laboratory. It consists of (1) water collection and filtration using a custom gravity sampler, (2) buffer selection for sample preservation and cell lysis for DNA, and (3) an assay based on a region of sxtA, DinoDtec lyophilized quantitative polymerase chain reaction (qPCR) assay. Water samples spiked with Alexandrium catenella showed a cell recovery of >90% when compared to light microscopy counts. The performance of the lysis method (90.3% efficient), Longmire’s buffer, and the DinoDtec qPCR assay (tested across a range of Alexandrium species (90.7–106.9% efficiency; r2 > 0.99)) was found to be specific, sensitive, and efficient. We tested the application of this workflow weekly from May 2016 to 30th October 2017 to compare the relationship between sxtA4 copies L–1 in seawater and PSTs in mussel tissue (Mytilus galloprovincialis) on-farm and spatially (across multiple sites), effectively demonstrating an ∼2 week early warning of two A. catenella HABs (r = 0.95). Our tool provides an early, accurate, and efficient method for the identification of PST risk in shellfish aquaculture.

An innovative passive sampling approach for the detection of cyanobacterial gene targets in freshwater sources.

Science of The Total Environment

Volume 892, 20 September 2023, 164593

David J. Redden, Toni Stanhope, Lindsay E. Anderson a, Jessica Campbell b, Wendy H. Krkošek b, Graham A. Gagnon

Abstract

Cyanotoxins pose significant human health risks, but traditional monitoring approaches can be expensive, time consuming, and require analytical equipment or expertise that may not be readily available. Quantitative polymerase polymerase Quantitative polymerase chain reaction reaction (qPCR) is becoming an increasingly common monitoring strategy as detection of the genes responsible for cyanotoxin synthesis can be used as an early warning signal. Here we tested passive sampling of cyanobacterial DNA as an alternative to grab sampling in a freshwater drinking supply lake with a known history of microcystin-LR. DNA extracted from grab and passive samples was analyzed via a multiplex qPCR assay that included gene targets for four common cyanotoxins. Passive samples captured similar trends in total cyanobacteria and the mcyE/ndaF gene responsible for microcystin production when compared to traditional grab samples. Passive samples also detected genes associated with the production of cylindrospermopsin and saxitoxin that were not detected in grab samples. This sampling approach proved a viable alternative to grab sampling when used as an early warning monitoring tool. In addition to the logistical benefits of passive sampling, the detection of gene targets not detected by grab samples indicates that passive sampling may allow for a more complete profile of potential cyanotoxin risk.

CLICK HERE TO READ THE PAPER

Use an Integrated Approach to Monitor Algal Blooms

A Texas drinking water utility found a comprehensive, cost-effective strategy for monitoring toxin-producing cyanobacteria that can harm water quality.

OpFlow is an award-winning magazine featuring how-to articles and case studies on water treatment and distribution. It is written primarily for water operators.

To read the OpFlow article, please click here.

Authors: Hunter Adams, Frances Buerkens, Ashley Cottrell, Sam Reeder, Mark Southard

December 2018

https://doi.org/10.1002/opfl.1113

Citations: 6

Alliance of Coastal Technologies (ACT) releases technical demonstration report for CyanoDTec and DinoDTec

Alliance of Coastal Technologies (ACT) releases technical demonstration report for the Phytoxigene™ DinoDTec and CyanoDTec quantitative real-time PCR (qPCR) kits. ACT is a partnership of research institutions, resource managers, and private sector companies dedicated to fostering the development and adoption of effective and reliable sensors and platforms for use in coastal, freshwater and ocean environments. ACT conducts two levels of Technology Evaluations: Verifications and Demonstrations. Technology Verifications focus on classes of commercially available instruments to provide confirmation that each technology meets the manufacturer's performance specifications or claims and/or provides verified data on those operational parameters that stakeholders require to make a use decision. The report is available here.

Click here to learn more about ACT.

Patent Filed for Novel Method to Detect Toxin in Fresh Water

Phytoxigene licenses guanitoxin gene technology from University of California - San Diego and now have launched a multiplex assay for the detection of anatoxin and guanitoxin production genes.

A new freshwater monitoring tool, which can detect a lethal toxin called guanitoxin in freshwater sources, is now available to public health officials thanks to technology developed at Scripps Institution of Oceanography at UC San Diego and the University of São Paulo. 

This novel technology has been licensed to the Australian company Diagnostic Technology, which is now offering guanitoxin monitoring kits under the brand Phytoxigene.

“It was really gratifying to be able to unlock how nature has solved this ability to make this toxin,” Scripps Oceanography marine chemical biologist Bradley Moore said about the research that led to the kits.

Guanitoxin is one of several neurotoxins produced by cyanobacteria, which proliferate to form harmful cyanobacterial blooms (cyanoHABs) in lakes and ponds. 

Harmful algal blooms (HABs) and cyanoHABs can contaminate tap water reservoirs and have caused significant public health emergencies. In 2014, Toledo, Ohio issued a “do not drink” advisory after a HAB outbreak led to toxins other than guanitoxin entering the city’s tap water supply. Essential healthcare treatments such as dialysis and surgery had to be halted. Additionally, people who swim in waters with HABs have suffered adverse health effects, ranging from vomiting to neurological impairment. These toxins have also been responsible for a number of dog deaths.

To continue reading the article, please click here.

CyanoDTec Now in Standard Methods!

The Standard Methods Committee (SMC) and Joint Task Groups (JTGs) have published the publication of Standard Method 10120: Quantitative PCR for Cyanobacteria and Cyanotoxin-Producing Genes, now available through Standard Methods for the Examination of Water and Wastewater. Jointly published by the American Public Health Association (APHA), American Water Works Association (AWWA), and the Water Environment Federation (WEF), SM 10120 provides a scientifically validated approach for detecting cyanobacteria and toxin-producing genes in environmental samples using quantitative PCR (qPCR). This method enables water utilities to make faster, more informed decisions when monitoring for harmful algal bloom events.

The method was validated through an international interlaboratory study involving 14 laboratories across Canada, Australia, New Zealand, France, and the United States. It demonstrated that qPCR technology can reach high levels of accuracy and reproducibility when combined with standardised reagents and characterised reference material. (AWWA Water Science, 2025 https://doi.org/10.1002/aws2.70018 ).

Cyanobacterial blooms are a growing global challenge, threatening drinking water supplies and public health. SM 10120 equips utilities with a rapid, reliable tool for early detection, enabling proactive management and reducing risks associated with cyanotoxins. 

Standard Method 10120 includes Detecting Cyanobacteria 16S rRNA and Microcystin/Nodularin-, Cylindrospermopsin-, and Saxitoxin-Producing Genes by qPCR – A detailed protocol for using a commercial qPCR assay to identify cyanobacteria and toxin genes.

READ THE PAPER HERE: https://www.standardmethods.org/doi/abs/10.2105/SMWW.2882.266

Abstract: 10120 A:2025 INTRODUCTION TO DETECTING CYANOBACTERIA AND TOXINS WITH qPCR

Quantitative polymerase chain reaction (qPCR or real-time PCR) is a molecular technique used for amplifying and detecting specific DNA molecules. In qPCR, the accumulation and amplification of DNA molecules are measured as the reaction progresses in a thermal cycler. DNA amplification is detected by fluorescence emitted from DNA-binding fluorescent dyes or fluorescently labelled specific oligonucleotides. Fluorescence measurements are proportional to the total amount of molecules produced and are used to calculate the initial amount of DNA molecules present in the reaction. qPCR reactions are highly sensitive over a wide dynamic range of DNA concentrations.

Significant efforts have been made to establish guidelines and protocols for qPCR assay development and validation.1 As a result, qPCR has been adopted for the microbial risk assessment of drinking water.2,3,4 Unlike microbiological culture methods that may take days to produce results, samples for qPCR can be prepared and analyzed in a few hours.5 For example, several environmental samples can be tested for cyanobacteria in a single run of qPCR assays. The savings in time includes the expertise, physical resources, and classification efforts required for the microscopic identification and quantification of the samples’ nontoxic and toxic cyanobacteria species.

Phytoxigene CyanoDTec is a molecular assay for cyanobacteria and toxin-producing genes based on qPCR. Other assays that meet the performance criteria in this method are considered equivalent and may also be used. The assay designed for aquatic environmental samples detects and quantifies the presence of cyanobacteria and their genes encoding toxin-production.6,7 Not all cyanobacteria species produce toxins; therefore, the presence of cyanobacteria does not immediately indicate the presence of toxins. With a high degree of reproducibility, this qPCR test quantifies both the amount of overall cyanobacteria present in a sample along with the number of genes that are responsible for the production of certain toxins.8 Toxins associated with cyanobacteria can be hepatotoxins or neurotoxins. The hepatotoxins include microcystin, nodularin, and cylindrospermopsin, while saxitoxin, anatoxin, and guanitoxin are the primary neurotoxins produced by cyanobacteria.

Abstract: Citation

Standard Methods Committee of the American Public Health Association, American Water Works Association, Water Environment Federation. Baxter TE, Lipps WC, eds. Assessment of Aquatic Biology: 10120 Quantitative PCR of Cyanobacteria and Cyanotoxin-Producing Genes. Standard Methods for the Examination of Water and Wastewater. 25th edition. APHA Press, 2028, p. x-x.

Interlaboratory Performance Study of Cyanobacteria DNA Reference Materials Using a qPCR for Monitoring Blooms

Leonardo B. Pinheiro, Mark Van Asten, Luminita Antin, Hunter Adams, Judy Y. Qiu, Mary Robinson, Suzane DeLorenzo, Robert Holmes, Megan Hurd, Rueyjing Tang, Kale Clausen, Justin Seikel, Rahana Sudhi, Paul Wright, Konstanze Steiner, Anne Gérard, Somanath Bhat, Anna Baoutina, Kerry Emslie

ABSTRACT

Digital PCR (dPCR) has increasingly been used as a primary measurement method for the characterization of nucleic acid reference materials. Nucleic acid reference materials are particularly useful when used for the validation and calibration of quantitative PCR (qPCR). In this study, we describe the development and characterization of Cyanobacteria DNA reference materials (RM) using dPCR. An international interlaboratory study involving 14 laboratories was conducted using the Cyanobacteria DNA RM in combination with a lyophilized PCR reagent designed for the monitoring of Cyanobacteria bloom events. Of the 55 scored study results obtained using qPCR-based techniques, 62% were within the 8% relative expanded uncertainty based on dPCR measurements, while 100% of the study results returned satisfactory z scores calculated using a set performance coefficient of variation equivalent to one Ct value. The study participants' results indicate that the cyanobacteria DNA RM is fit for the purpose of method validation and quality control of the qPCR format used for monitoring toxic cyanobacteria algae bloom events. Most importantly, the study results demonstrated that the use of standardized reagents combined with highly characterized nucleic acid RMs allows qPCR-based DNA quantification technology to reach levels of accuracy and reproducibility comparable to those achieved with digital PCR technology.

READ THE PAPER HERE: https://awwa.onlinelibrary.wiley.com/doi/10.1002/aws2.70018