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Cyanobacteria (blue-green algae): What's All the Fuss About?

Cyanobacteria (aka blue-green algae) has been making the national headlines in recent weeks particularly in conjunction with pet deaths and other health implications. This has raised a number of questions about water safety and if blooms are occurring in the Pomperaug River. The short answer is no - we have not seen or heard reports of cyanobacteria blooms in the Pomperaug. Nonetheless, we decided to create this blog post to help you better understand what the fuss is all about and what to watch out for.
About Cyanobacteria

Cyanobacteria (a.k.a. Blue-green Algae), What is It? Cyanobacteria are bacteria. They occur naturally in freshwater lakes, rivers, and ponds. Like plants, they use the process of photosynthesis to convert sunlight into food and energy, but with pigments other than green. Unlike plants, the color pigment of cyanobacteria is blue-green and it has other unique properties. Due to these properties it is referred to as "blue-green algae". Typically blue-green algae cannot be seen by the naked eye however, under certain conditions it can grow abundantly and appear as a bloom.

Why are Cyanobacteria toxic? Cyanobacteria can become toxic in high abundance. Over billions of years, they evolved the process of producing toxins to ward off predators. When cyanobacteria populations become over-abundant the toxins they release can become dangerous to human and animal health. To learn more about health concerns please visit CT DEEP's website by clicking here. What Causes the Blooms? Blooms usually occur when there is an imbalance of certain factors in the water column. Excess nutrients and warm water temperatures increase the likelihood of blooms. Shallow and slower flowing bodies of water are easily impacted by Cyanobacteria. Shallow waters allow the sunlight to reach most of the bottom of the water column, which mobilizes the nutrients found in the sediments, which feeds the cyanobacteria. Not all blooms are caused by the exact same factors. Humans also contribute to nutrient loading in bodies of water by improperly using fertilizers, ineffectively controlling storm-water runoff, and poor septic system maintenance.

Factors that Influence Blooms (Lake Champlain Basin Program, 2015).

What do Blooms look like?

Cyanobacteria blooms frequently appear as a pea-soup green or blue-green color. Coloration may vary depending on the abundance and species preset. Indications of a bloom include increased cloudiness and blue-green pigments throughout the water column, thereby making it hard to see the bottom of the water column. Cyanobacteria can control where they are in the water column by changing their buoyancy. When certain conditions occur, cyanobacteria will rise up to the water's surface. Wind blowing across a water's surface concentrates the cyanobacteria in localized areas. These conditions produce a scum on the water's surface that resembles green paint. Thick scums are potentially more toxic due the high concentrations of cyanobacteria and contact should be avoided.

A Blue-Green Algae Bloom at Kettletown State Park (H John Voorhees III / Hearst CT Media, 2019).

Cyanobacteria Health Risks

What health risks do Cyanobacteria pose to humans?

Short-term and long-term exposure to Cyanobacteria toxins can lead to adverse health effects. Health reactions vary depending on the toxin concentrations in the water, the pathway of exposure, and previous health status of patient. Take extra precaution if you suffer from: liver disease, kidney disease, cancer, asthma or other lung ailments, or are immunocompromised. Young children and the elderly face a higher risk of symptoms following exposure.

Exposure to Cyanobacteria toxins can cause skin and mucous membrane irritations as well as damage to vital organs and nerves. The most common effect is a skin reaction after direct contact, but GI and respiratory effects are also possible.

The more direct contact someone or an animal has with the water during a cyanobacteria bloom, the higher the possible risk of exposure to their toxins. If you are someone that enjoys aquatic recreational activities especially in the summer months, your level of exposure is something to keep in mind.

Please read CT Department of Public Health's Guidance to Local Health Departments for Blue-Green Algae Blooms in Recreational Waters document to learn specifics.

Potential Exposures to Blue-green Algae Blooms (CT DPH, 2019).

Concerns for Domestic Pets, Livestock, and Wildlife Animals can also suffer from the harmful effects of toxic cyanobacteria blooms. In fact, Lake Champlain in Vermont had such bad algal blooms in the summers of 1999 and 2000 that two dogs died from ingesting the cyanotoxins in the water. The precautions are similar for human and domestic animals. For more information on animal safety please visit the CDC's Animal Safety Alert document. Some of the resources above also have animal health information.

What should you do if you or your pet has been exposed to a bloom? Recommendations from the CDC:

  • Rinse off skin and pets with fresh water as soon as possible, do not let pets lick cyanobacteria off their fur.

  • If you or your pet swallow water with a bloom, call your doctor, Poison Center, or a veterinarian.

  • Call a veterinarian if your animal shows any of the following symptoms of cyanobacteria poisoning: loss of appetite, loss of energy, vomiting, stumbling and falling, foaming at the mouth, diarrhea, convulsions, excessive drooling, tremors and seizures, or any other unexplained sickness after being in contact with water.

Fish Consumption Advisory

Fish caught in waters that have experienced recent blooms can accumulate toxins in their bodies, primarily internal organs and not muscle. The CT DPH advises eating fish from water bodies with blooms in moderation (1 - 2 meals/week). Remove skin and internal organs before cooking and wash fillets before cooking and freezing.

Additional Health Resources

How to Report a Bloom

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