Algal blooms are a common occurrence in Australian waterways and can significantly affect water quality. Blooms typically occur in warmer months when the growth of harmful algae may be favoured over non-harmful algae. Hot, dry conditions can result in limited water movement or lack of turbulence which promotes algae growth. The presence of nutrients such as nitrogen and phosphorus, arising from human activities including agricultural practices and effluent discharges, can enhance blooms.

Algal blooms produce a scum on the surface of waterways which is typically green or reddish brown and often produces an odour. As more algae grow, other algae and plants die off and decay. The subsequent breakdown of this organic matter by bacteria reduces oxygen levels which can cause waterways to become stagnant and cause fish to die. The unsightly nature and smell of algal blooms prevent humans from entering potentially contaminated waterways.

Some forms of algae such as blue-green algae (or cyanobacteria) can produce toxins in water which cause unfavourable health effects to humans and wildlife by damaging the liver or the nervous system. Ingestion may cause symptoms such as diarrhoea, nausea, headaches and cramps. In New South Wales, there have been reports of dogs dying after swimming in contaminated waterways by ingesting toxins when swallowing the water, or when licking the algae from their fur. Post mortems revealed severe liver damage as the cause of death. Blue-green algae blooms are not always toxic but it is still unknown what triggers these algal blooms to release toxins.

Algal blooms frequently occur in water supply reservoirs used to provide potable water and are of particular concern to water authorities. Algae can interfere with the treatment process by physically blocking filters used to remove suspended material from raw water. Treatment systems such as the installation of activated carbon filters are usually required to eliminate any potential toxins.

Blooms in reservoirs or waterways used for recreational purposes, such as swimming or boating, also need to be identified to ensure the public is aware of the bloom and warned not to use the water body. Livestock and other animals should be fenced off from this water body where possible.

Monitoring for algal blooms is therefore an essential component of water quality monitoring programs. Samples are collected in a plastic bottle that inhibits the penetration of light and is preserved with Lugol’s solution. Algae are analysed microscopically by a Phycologist to identify particular algae species. This is a labour intensive process, and may take over an hour to identify and count all of the algae in a particular water sample. Where a high number of a blue-green algal species are detected, the sample is analysed chemically to identify the presence of the toxin that is produced by that particular toxic species.

Symbio Laboratories provides appropriate sample bottles for algae collection and has a team of Phycologists and Chemists who count and identify algae species and toxins. For more information about how Symbio Laboratories can assist you with your algae testing requirements, simply call 1300 703 166 or email

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