Cyanobacteria 101: Solving A Dangerous Problem

The final and ultimate stage of eutrophication is when cyanobacteria dominance becomes permanent in a lake. Cyanobacteria are often thought of as algae, but they are not. They are photosynthetic bacteria with chlorophyll-a and bluish accessory pigments called phycobilins, hence the colloquial name “blue-green algae.” These prokaryotic bacteria are a dead-end ecologically and aesthetically, and perhaps worst of all, they can produce potent toxins such as:

• Neurotoxins (anatoxins and saxitoxins) – cause rapid paralysis of skeletal and respiratory muscles (minutes).
• Hepatotoxins (microcystin, cylindrospermopsin, nodularins) – disrupt proteins that keep the liver functioning, may act slowly (days to weeks).
• Dermatotoxins (lyngbyatoxin, aplysiatoxin, debromoaplysiatoxin) produce rashes and other skin reactions, usually within a day (hours).

Each year, acute toxicity of cyanobacteria toxins can be directly related to fish, livestock, waterfowl, and dog deaths worldwide. Acute toxicity of cyanobacteria toxin exposure to humans results in many becoming ill each year and, in some cases, causes death. The low-dose, long-term exposure to cyanobacteria toxins by people consuming fish, drinking water, or even living near lakes (aerosolized toxins) with cyanobacteria has resulted in increased health risks of Amyotrophic Lateral Sclerosis (ALS), Alzheimer’s, Parkinson’s disease, liver cancers, and tumor production (Caller et al. 2009; Bradley et al. 2013). These health implications have led organizations like the World Health Organization (WHO) to establish public health guidelines as outlined in Table 1 (Christoffersen and Kaas 2000; Zanchett and Oliveira-Filho 2013; Chorus and Welker 2021).

Major Problematic Freshwater Cyanobacteria

Of the thousands of cyanobacteria that have been identified, only a few (~100) major culprit species exist in three classes and six orders when using modern taxonomic classification.

Class Synechococcineae

Order Pseudanabaenales (e.g. Pseudanabaena, Schizothrix, Spirulina)

Fig 2. Spirulina

Class Oscillatoriineae

Order Oscillatoriales (e.g. Lyngbya, Oscillatoria)

Fig. 5 Lyngbya

Class Nostocineae

Order Nostocales (e.g. Anabaena, Cylindrospermopsis, Scytonema, Stigonema)

Fig. 7 Scytonema

What Makes Cyanobacteria So Competitive?

• Superior growth and photosynthesis at higher temperatures (>86ºF). Store sugars as food reserves—they are best metabolized at higher temperatures.
• High affinity for nitrogen and phosphorus when nutrient limitation is most severe. Can perform luxury nutrient uptake and storage.
• Ability to regulate their position in the water column by gas vacuoles to take advantage of areas richer in nutrients and/or light.
• Superior light-capturing abilities when self-shading is the greatest.
• Reduced zooplankton grazing via toxin production and having poor nutritional value.
• Superior uptake kinetics for inorganic carbon (low CO₂ / high pH waters).
• Can fix atmospheric nitrogen.

Key Management Thresholds

Based on decades of research, almost all freshwater cyanobacteria blooms are driven by nutrients, primarily phosphorus and nitrogen. Phosphorus tells us how severe a cyanobacteria bloom can be (the number of algae and toxins present), while nitrogen tells us the type of species present (toxic vs. non-toxic). In general, it is recommended that total phosphorus levels be maintained at < 24 µg/L P and total nitrogen at < 850 µg/L N for swimming recreation waters. The ideal total phosphorus and nitrogen level for fisheries management is < 48 µg/L P and <1,200 µg/L N. Maintaining these thresholds will significantly reduce the chances of cyanobacteria blooms. While these are helpful starting thresholds, developing a lake-specific nutrient criterion based on individual lake characteristics is best.

Management Solutions

Typically, treatment for cyanobacteria blooms takes a reactive approach by using algaecides. There are many different algaecide formulations, and selecting the right one will depend on your lake goals and the type of cyanobacteria present. Incorporating biocatalysts such as Pondzilla Pro and AquaSticker with your algaecide treatments will improve efficacy and degradation dramatically. Then, adding Temperature Driven Solutions post-treatment will counter many of the negative impacts of algaecides (bacterial sterilization) and prolong treatments 2-3 folds.

A more proactive approach to permanently stop cyanobacteria blooms from forming is by incorporating nutrient removal products to your regular pond maintenance. Natural Lake Biosciences’ nutrient mitigation products allow lake managers to set specific nutrient criteria for phosphorus and nitrogen. Products like MuckBiotics, MetaFloc, and Water Column Clarifier can not only address these specific nutrient concerns but can help aid in creating a healthier environment for your water body. Product selection and dosing will depend on the sources and forms of nutrient loading. Contact a certified Natural Lake applicator for more information regarding cyanobacteria management solutions.