A sign in Burlington, VT indicating a closed beach due to cyanobacteria.

Cyanobacteria: All You Need To Know

By Noah Johnson, Museum Educator

Cyanobacteria. It’s one of the most common buzzwords thrown around during the summer surrounding Lake Champlain, but what exactly is it? In this blog, we will break down what exactly cyanobacteria is, how to stay safe, and how you can help.

What is cyanobacteria? Cyanobacteria is a bacteria that produces cytotoxins (a group of toxins). When there is a large quantity of cyanobacteria in the water (known as a bloom), the water can become harmful to the local ecosystem and to us humans. Side effects of swimming in a cyanobacteria bloom can range from minimal skin irritation and, in the worst cases, death. Always check your local news and beaches to see if there is a cyanobacteria bloom in your area before you plan a swimming trip.

You can also check the website https://www.healthvermont.gov/tracking/cyanobacteria-tracker which can lead you to an interactive map to show where blooms are happening so you can stay safe.

A sign in Burlington, VT indicating a closed beach due to cyanobacteria
A sign in Burlington, VT indicating a closed beach due to cyanobacteria. Keep an eye out for signs like these at your local swimming/recreational spots and make sure to listen to them!

If you think you’ve spotted cyanobacteria, it is always better to play it safe. It is better to incorrectly identify cyanobacteria and not go in the water than to dismiss it and get sick from cyanobacteria. Some ways to spot cyanobacteria are large swaths of green with a paint-like sheen or the water looking like pea soup. You can also perform the “stick test.” With this test you take a stick and put it in the water and try to gather the bloom. If the bloom sticks to the stick, you are dealing with algae or some other aquatic plants. If nothing sticks to the stick, it is most likely cyanobacteria.

A major cyanobacteria bloom with a very green, paint-like sheen on the surface of the water
A major cyanobacteria bloom. Note the paint-like sheen on the surface of the water.

Cyanobacteria blooms can also have a significant impact on the local ecosystem. Blooms will take a lot of oxygen out of the water, leading to a mass culling of fish, plants, and many other aquatic creatures. It can also lead to serious dangers to our pets. Dogs and cats don’t know what cyanobacteria is and may drink it. If they ingest cyanobacteria that could lead to serious health complications. If your pet drank from or swam in a cyanobacteria bloom, bring them to the veterinarian.

Cyanobacteria is found in nearly every body of water, but usually in small enough quantities that it is essentially harmless. It is only when there is a cyanobacteria bloom in the water that it starts to cause problems. So what causes a bloom of cyanobacteria in the first place? Before we can answer that, we need to ask another question. What causes the bloom of any bacteria, algae, or any living being in the first place? The answer to that is an excess of resources that allows for the growth of that species. Cyanobacteria blooms are no different. An excess of nutrients in the water and an increase in water temperatures allow for the cyanobacteria to multiply rapidly, creating a bloom.

A pea-soup-like texture cyanobacteria bloom in the Museum's North Harbor
A cyanobacteria bloom in our own North Harbor. Notice how it looks almost like pea soup!
This was taken 7/20/2022, which was an extremely hot day.

So we know that an excess of nutrients creates these blooms, but which nutrients in particular? According to a paper published in 2019, cyanobacteria flourishes on nitrogen and phosphorus. Well how does the cyanobacteria get an excess of nitrogen and phosphorus? Look no further than fertilizer. The Environmental Protection Agency (EPA) says that, “most fertilizers that are commonly used in agriculture contain the three basic plant nutrients: nitrogen, phosphorus, and potassium” (EPA). But how does the fertilizer get into the lake? Our answer is runoff. Runoff is when rainwater that can no longer be drained by the soil flows toward the lowest point, often to lakes, rivers, and streams. This runoff can carry any chemicals left on the surface, including the nutrients used in fertilizer. We can hopefully see now how this is yet another environmental problem. Large scale agriculture and the excess use of fertilizer has been adding nutrients to the water via runoff for many many years at this point, and we’re doing little to stop it.

As much as I would love to tell you there is a simple solution that you can do at home, there isn’t. Change is going to have to come from government regulation, and while we have the Clean Water Act enacted in 1972, runoff isn’t covered in the original or any modifications of the bill. So what you can do is two-fold. The first is you can inform your friends, family, and neighbors about cyanobacteria and its dangers. Rally your community to put pressure on the local, state, and eventually federal government to address this and to keep our waters safe. The second thing you can do is to become a volunteer monitor for Lake Champlain. This would give you the opportunity to help your local community and the wider Lake Champlain community to ensure everyone and everything has a healthy and happy lake.