Prediction & Detoxification Tactics on CyanoHABs
INTRODUCTION
No US state is safe from cyanobacterial harmful algal blooms (cyanoHABs). CyanoHABs pose a major threat to public health, wildlife, communities, businesses, and the general ecological integrity of all 50 states. Therefore, it is crucial to analyze methods of early detection and detoxification to better prevent and mitigate the damage done by cyanoHABs.
What are cyanoHABs?
CyanoHABs refers to the Harmful Algal Blooms caused by cyanobacteria. Its previous misnomer "blue-green algae" has brought confusion, but in fact, cyanobacteria is NOT algae.(Washington State Department of Health, n.d.)
Main factors of cyano-blooming/proliferation:
warm water: blooms peak around late summer,
eutrophication: the overabundance of nutrients in the water, particularly phosphorus) (Indiana University Purdue University Indianapolis (IUPUI), n.d.).
What's so bad about cyanoHABs?
No US state is safe.
While large in the Great Lakes and other neighboring fresh bodies of water, all 50 US states have reported cyanoHABs (U.S. National Office for Harmful Algal Blooms, n.d.).
Worse with Climate Change.
Due to their proliferation factors favoring warmer waters, cyanoHABs are expected to worsen in severity and duration due to climate change (U.S. Environmental Protection Agency (EPA), 2024a).
Toxins and Taste & Odor Compounds
Not only do their blooms create deadly hypoxic conditions, but certain strains can produce taste-and-odor (T&O) compounds and cyanotoxins. These toxins are poisonous to consume and will lead to illness in wild and domestic animals. Cyanotoxins can be:
neurotoxins: damage to the nervous system
dermatoxins: damage to the skin
hepatotoxins: damage to the liver
endotoxins: damage to the immune system
Notoriously found at Lake Erie, the cyanotoxin microcystin is a possible carcinogen, with a potency more lethal than cyanide, botulinum, or DDT (Ohio Environmental Council (OEC), 2015; U.S. National Office for Harmful Algal Blooms, n.d.-b; Indiana University Purdue University Indianapolis (IUPUI), n.d.-a; n.d.-b).
RESEARCH QUESTION
How can prediction and detoxification tactics be utilized in tandem to reduce the negative impacts of cyanotoxins from cyanoHABs in the Great Lakes?
LITERATURE REVIEW
Physically
(wind, abrasion, bead beating, etc.)
Virally
(cyanophages)
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).
Chemically
(strong acids, algicides with hydrogen peroxide and/or copper sulfate, etc.)
Naturally
(apoptosis)
PREDICTING
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).
DETOXIFYING
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/
METHODOLOGY
Note: The red asterisks (*) is used after verbs that can show up in alternative conjugations. For example “model*” will bring up “model”, “models”, “modeling” so on and so forth in the keywords of articles.
meta-analysis of these 3 databases were used:
Utilizing the advanced search option, only the following parameters were included:
open-access
peer-reviewed
available in English
01 January 2000 - 31 December 2023
Not included: meta-analyses, books, and other reviews.
In the advanced search, the Boolean operators AND, OR, as well as the asterisk (*) were used in the query as seen in the flow chart to the left.
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