Posted By: Clare Suggett

Have you heard of cyanobacteria? How about blue-green algae? These are both terms referring to a microscopic organism found in water, which in nutrient-rich environments can cause an algae bloom! An algae bloom is concerning in aquatic environments as the rapid increase of algae alters the quality of the water. 

What is Cyanobacteria?

Cyanobacteria is a microscopic organism that occurs naturally in most water systems and uses sunlight to make their own food. However, when a water system is nutrient-rich (high in phosphorus and nitrogen) they will reproduce more quickly resulting in a bloom. 

There are two main ways humans can be exposed to cyanobacteria during a bloom:

  1. Through drinking water or foods that were contaminated with the bacteria
  2. Swimming in water during an active bloom 

Cyanobacteria blooms can be in many forms such as foam, scum, or a mat across the surface and can be different colours ranging from blue, bright green, brown, or red. If you are unsure about the quality of the water, it is better to avoid coming into contact with it and checking with your local health authority. It is important to keep dogs and young children away from suspected blooms as they may be less cautious and less aware of the danger. Boiling water will not remove cyanobacteria from the water, so you should never drink from a contaminated source. 

Cyanobacteria blooms are not a big concern for Lake Windermere as they typically form when water is shallow, warm and slow-moving or still. Since Lake Windermere is a widening of the Columbia River, there is a high volume of water entering and leaving the lake on a regular basis. This results in the lake having a quick flushing rate of 47 days which means nutrients are removed fairly often. Additionally, Lake Windermere is generally considered oligotrophic which means that it contains low levels of nutrients like phosphorus and nitrogen that are required for blooms. 

Although cyanobacteria cause toxic algae blooms, it isn’t all bad! Cyanobacteria has been around for an estimated 3.5 million years and due to that has played a large role in why the Earth has evolved to its current state. Firstly, the oxygen that we depend on today was created by cyanobacteria during the Archean and Proterozoic Eras, which completely altered the composition of the atmosphere. The other significant role cyanobacteria have played was the creation of plants. Plants are made up of chloroplast which at a microscopic level has cyanobacterium living within the plant’s cells. 

What is an Algae Bloom? 

Algae blooms are identified by discoloration of water caused by phytoplankton species such as cyanobacteria. These blooms are most common in late summer to early fall and can last days, weeks, or even months! Impacts of algae blooms vary but one concern is that as the number of bacteria increases, so does their need for dissolved oxygen, taking away from fish and aquatic insects. Algae blooms are a natural occurrence but may still be harmful to fish species and humans, so if you suspect one is occurring it is vital to report it to your local health authority so it can be investigated further.

Algae blooms are naturally occurring but can be amplified by humans adding excess nutrients that provide more food for bacteria. Three things you can do to prevent cyanobacteria blooms include:

  1. Use only the required amount of fertilizers so any excess isn’t running off into the water source
  2. Ensure your septic system has no leaks
  3. Maintain natural shoreline vegetation so it can filter out any nutrients before entering the water.

Although cyanobacteria are naturally occurring, there are steps we can take to reduce the chances of having algae blooms in our local waters. It’s important to protect our lakes not only for our enjoyment but for the aquatic species that rely on clean water as well.