Blue-Green Cyanobacteria: Not such a pretty color


I like the color teal or aquamarine or whatever you want to call it but…

What shut down the water supply system in Toledo, Ohio in 2014?

What causes off-flavor issues in commercial aquaculture fish, both tilapia and catfish?

What kills wildlife and pets randomly when swimming in or drinking from ponds?

What kills the fish in your pond when you are trying to control algae in your pond?

What makes an unpleasant odor on your neighborhood while walking around the pond or lake?

All of these problems are caused by cyanobacteria, otherwise known as blue-green algae, which makes blue-green not such a pretty color. This is not a true algae, but a type of bacteria that uses photosynthesis like a plant. It is not very efficient at photosynthesis and doesn’t produce a large increase of oxygen in comparison to a green algae population. The appearance is a grainy collection of particles in the water column with very small clumps of cells that you can see when you get only a few feet away. When it piles up on an edge or in a corner or cove from wind action it floats and is a bright forest green color, giving the appearance of green paint floating on the surface. If you see this with the previous description in mind, you will recognize it, and it will likely have a bad odor.

Infestations are becoming more common in our area, be it weather conditions or nutrient levels. When it populates a pond or lake there are several negative effects. First, it tends to dominate and will outcompete your healthy green phytoplankton (desired in fish production ponds and healthy biology). Secondly and more important, this alien creature makes toxic byproducts: 1. residual chemical compounds that reside in the mud giving fish bad flavor, and 2. Neurotoxins, hepatotoxins, and dermotoxins (brain, liver, and skin toxins respectively)… sometimes. When it does, it then is classed as an HAB, harmful algae bloom.,

The randomness of these toxic effects lulls most people into a casual attitude about it, and then they bloom toxic and create an issue. Toledo, OH did in fact, have to shut down their entire water supply system in the summer of 2014 and truck in water for 400,000 citizens for 3 days. The challenge of this algae in a water system is that when it is killed by traditional algaecides, the toxins remain and release. The toxins are more difficult to filter and remove than the algal cells.

Blue-green algal toxins are directly responsible for the death of many dogs that swim in a pond, then lick their fur after swimming. Wildlife is also affected and blue-green toxins in 2005 are directly responsible for the death of over 160 bald eagles in the southern United States.

Some scientists are quick to point directly to pollution, specifically phosphorus, then they point to nitrogen. This is an easy target and they point to farms, then lawns. It is all easy talking points and traditional targets however, it just doesn’t always fit the model. Since blue-green algae can fix nitrogen from the air, they don’t need nitrogen from a polluting source.

What should you do if you have blue-green algae in your pond?

Keep the pets, and kids out of the pond until it is diminished from rain or treatment.

Consider having the pond treated by a professional. Even if you have treated other algae successfully, this is different. Treated with traditional algaecide, it can release toxins and kill fish. We have bacteria applications that can help to settle and outcompete blue-greens and control them while avoiding toxin release.

Consider aerating the pond or lake. Blue-greens need to dominate the top of the water column since they need a longer photoperiod with longer exposure to sunlight to out compete healthy green phytoplankton. With mixing of the water with properly selected and installed aeration, the water is mixed from top to bottom and the algae is not able to control its place in the otherwise stagnant water and then the population begins to retreat. We provided aeration design and equipment for a water reservoir in Syracuse, New York in 2017. The first year the copper algaecide was reduced by 75% and in 2019 they were at 5% of 2016 algaecide usage. Aeration doesn’t always work this well but it has many benefits for ponds with mixing and cooling as well as helping cycle and process nutrients in a healthy fashion.

Control obvious pollutants. Nutrients can play a part and it is not a good idea to dump grass clippings in a pond or blow them in with a directional mower. Keep livestock access to specific areas of the pond to avoid manure. Avoid feeding and attracting large numbers of waterfowl. For more urban locations, consider pet waste, and storm drains where pollutants can enter – yard waste on the curb, a messy dumpster location.

Don’t freak out. Just be aware. Blue-green algae is common. Heavy blue-green algae and repeated/persistent infestations increasing over time are something to be concerned about enough to consider addressing. If you have a suspected infestation, don’t hesitate to contact us at (225) 308-4145. We would be glad to help identify if for you!

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