Blue-green algae

Did you know, blue-green algae are not algae at all.

They are photosynthetic bacteria (also called ‘cyanobacteria’) that rely on sunlight for energy.

Blue-green algae are present in almost all aquatic ecosystems, including creeks, rivers, lakes and wetlands.

Individual cells are very small, so blue green algae can be present in a water body without being visible.

These cyanobacteria are an important part of a healthy ecosystem. They perform functions like photosynthesis, nitrogen fixation and nutrient cycling in the food chain.

Health Risks

Blooms of blue-green algae can pose significant risks to wildlife, pets, and human health by producing toxins.

Blooms also cause water discolouration, scum and odorous compounds.

Blue-green algae toxins can affect us in three main ways:

  • Hepatotoxins damage the liver and may also increase the risk of certain types of cancer.
  • Neurotoxins damage nerves and can cause numbness and muscle tremors
  • Allergens are thought to produce a range of reactions like:
    • skin rashes
    • irritation of the eyes, and
    • gastroenteritis.

Blue-green algal toxins are colourless, odourless, and can remain present in the water weeks after the algae have disappeared.

They are not destroyed by boiling the water.

Blue-green algae blooms

Blue-green algae can bloom quickly under the right environmental conditions. These include:

  • abundant sunlight
  • warm temperatures
  • still water, and
  • sufficient levels of nutrients (especially nitrogen and phosphorus).

Nutrients are either naturally present in sediments or wash from the surrounding catchment (agriculture, sewage effluent and stormwater run-off).

Helping prevent blue-green algae blooms

We can help prevent blue-green algal blooms by limiting the amount of nutrients in the water and promoting ecological health.

Detergents and fertilisers contain a high concentration of nitrogen and phosphorus, so we can all play our part by:

  • preventing nutrients from washing into roadside drains (e.g. by washing the car on the lawn rather than on the road)
  • using phosphorus-free detergents
  • reducing the use of fertilisers
  • helping to rehabilitate waterways, and
  • preventing land erosion, where possible, to stop soil washing into waterways.

Reporting blue-green algae blooms

For any algal bloom outbreaks in ornamental or recreational lakes and reservoirs in Logan, please:

To report other algal bloom outbreaks, please visit the Queensland Government website for a list of contacts.

Helpful links

You can visit the below websites for more information: