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Species of the Month: Microcystis aeruginosa

Sep 2023

As average temperatures increase each year across the globe, surface waters are seeing a surge in Microcystis aeruginosa, aka blue-green algae. This toxic phototropic bacterium is one of the most common bloom-forming cyanobacteria found in freshwater. If not treated right away, these harmful algae reproduce uncontrollably and go on to create environmental and public health concerns.

Algae blooms with Microcystis aeruginosa can deplete oxygen from the water and block out sunlight, wreaking havoc on aquatic ecosystems and drinking water processes. Once the algae die and the cells break open, microcystin toxins are released into the water source. The toxins can be lethal to dogs, cats, fish, wildlife and livestock. Humans exposed to Microcystis blooms have experienced skin irritation, burns, blisters, vomiting, fever, pneumonia and nausea. Prolonged exposure to the toxin can cause liver and kidney damage in humans.

While most strains of the bacteria are found in warm freshwater, there have been reports of Microcystis aeruginosa in brackish waters such as swamps or estuaries. The thick swaths of Microcystis typically show up in early summer through late fall in slow-moving waters with high nitrogen or phosphorous levels. Ideal water temperatures for the bacteria to proliferate are between 75 and 93 degrees Fahrenheit.

When viewing the bacteria in question, look for small pin-sized particles in the beginning stages. As it grows, the large patches of bacteria resemble pea soup or a blue-green paint spill on the surface. Microcystis aeruginosa blooms let off a pungent odor as well. If left untreated, the bacteria can cover the entire body of water.  

If you suspect you’re looking at Microcystis aeruginosa, don’t swim or boat in the water. And don’t allow pets or livestock to go near the water either. 

Contact your local UPL Aquatics representative to discuss SYMMETRY® NXG aquatic algaecide and HYDROTHOL® 191 aquatic algaecide and herbicide as two options for combatting Microcystis aeruginosa.

SYMMETRY NXG aquatic algaecide works quickly, and there are no water use restrictions. It can be tank-mixed with HYDROTHOL 191 or other aquatic herbicides to improve efficacy on algae. HYDROTHOL 191 works relatively quickly, providing algae control in just a few days, with no water use restrictions either.

Microcystis aeruginosa may be a growing issue, but with the proper solutions it doesn’t have to impact the surface water and ecology on your property for long.