Prediction & Detoxification Tactics on CyanoHABs

Although the common strains in the Great Lakes can produce toxins, this does not directly translate to the toxicity level. Cyanotoxins and T&O compounds are both predominantly produced intracellularly, so the more cells intact, the fewer potent compounds outside (EPA, 2024b). Unfortunately, this calculation gets complex with the wide range of variables impacting the rupture rate of cells. The 4 categories of variables that impact the release of intracellular cyanotoxins are seen in the diagram (EPA, 2024b; Mehdizadeh et al., 2023).

Trying to accurately forecast future algal blooms, including their potential toxicity levels is not without its nuance. Aerial monitoring is commonly used today to keep watch on the Great Lakes, but the forecasting piece is more difficult. Current research into the possible predicitve tools in order to forecast HABs are below:

• machine learning and artificial intelligence models like XGBoost, Random Forest, and Support Vector Machine.

• remote sensing and satellite-based monitoring rely heavily on Envisat-MERIS and current Sentinel-OLCI observations.

• monitoring the release/fluorescence of free/unbound phycocyanin pigments can reveal cells are about to lyse.

• (Percival & Williams, 2013; National Oceanic and Atmospheric Administration (NOAA), n.d.; U.S. National Office for Harmful Algal Blooms, n.d.-b; EPA, 2024b). 

46 of cyanobacteria's 2000 species are toxin-producing. Table 1 and its corresponding colored pie chart, show the taxa and toxins of the 5 most commonly reported toxin-producing strains found in the Great Lakes. Because the strains can vary greatly in shape, size, cellular structure, toxin production, and other physiological characteristics that make them strong competitors, detoxification strategies need to be varied and ready to go. 

Current detoxification and upcoming methods are as follows: 

• Removal of intact cells: 

  • coagulation/flocculation/filtration: adding a chemical coagulant to bind with the selected particles, creating larger aggregates easier to filter out.

• Detoxification of free toxins:

  •  algicides containing hydrogen peroxide and/or copper sulfate, chlorine; 

  • utilizng bioagents: sophorolipids (SLs) biosurfactants made by Starmerella bombicola, Penicillium sp. GF3 a fungus, ciliate Paramecium jenningsi as a bioagent to eat the raciborskii strain;

  • utilizing iron-based methods: the oxidation of magnetic zero-valent iron nanoparticles (nZVI) and ferrate ion ((FeO42-)-O-VI,Fe(VI)) leads to the degradation of cyanobacteria along with reducing the amount of phosphate available aqueously.

  • (Percival & Williams, 2013; National Oceanic and Atmospheric Administration (NOAA), n.d.; U.S. National Office for Harmful Algal Blooms, n.d.-b; EPA, 2024b). 

 Note: Identified toxins during environmental testing of HAB events, 2021. Retrieved from: https://www.cdc.gov/habs/data/2021-ohhabs-data-summary.html 

Table 1. Taxa & Toxins of The most common species of toxic cyanobacteria in the Great Lakes. Note: Adapted from U.S. National Office for Harmful Algal Blooms. (n.d.-b). HAB Species by  Name. Harmful Algae. Retrieved March 20, 2024, from https://hab.whoi.edu/species/species-by-name/