Toxic 'algal' blooms in Western Australia are common seasonal events that occur in natural waterways and man-made reservoirs such as farm dams. Blooms are more frequent in warmer months following rain events and in shallow water bodies with hard, alkaline water rich in nutrients.
In WA, the main organisms associated with toxic freshwater blooms are cyanobacteria (colloquially known as blue-green algae - a phylum of photosynthetic bacteria).
Cyanobacteria produce toxins collectively referred to as cyanotoxins. Consumption of water containing these toxins may result in poisoning and sudden death in livestock.
Test dam water if any of the following are observed:
- sudden change in water colour
- presence of bloom or floating scum
- foul chemical or sewage-type odour
- refusal of livestock to consume the water.
Prevent access to a waterway when toxic algae poisoning is suspected.
Sample water containing the blue-green 'algae' and send to DAFWA Diagnostic Laboratory Services (DDLS) for microscopic identification.
Courier water samples to:
DAFWA Diagnostic Laboratory Services
Department of Agriculture and Food, Western Australia
3 Baron-Hay Court, South Perth WA 6151
Water sampling procedure
Avoid contact with the suspect water as acute skin and respiratory irritation can occur after short-term exposure to water containing cyanotoxins.
- Wear gloves and wash hands afterwards.
- Collect water in a watertight plastic or glass bottle with a wide mouth. A clean, disposable water bottle is suitable if no other containers are available.
- Clearly identify each sample container.
- Sample surface water where the bloom is most dense (100 millilitres is sufficient, no more than 500mL). Ensure sufficient space is left at the top of the container to allow mixing.
- Thoroughly wash the exterior of the bottle with clean water.
- Samples should reach the laboratory within 24 hours and be kept at approximately 4°C during transport (an ice brick and small esky is usually adequate).
- Do not freeze the water as algal cells may be damaged making identification difficult.
For more information, see the webpage How to avoid poisoning of livestock by blue-green algae [1].