Different factors influence blue-green algae growth in different areas, including nutrients, temperature and flow. Blue-green algae blooms are common in the Gippsland Lakes due to this, and some major blooms have grown in recent years.
Some species of blue-green algae produce harmful toxins. Toxins can accumulate in aquatic organisms like shellfish, prawns and fish, passing the toxins along the food chain. This can make it unsafe to eat seafood from these areas during a bloom.
Seafood health risk assessment
Levels and types of algae in the Gippsland Lakes are monitored regularly by government agencies. The area is monitored monthly in winter, fortnightly in spring and autumn, and weekly during the summer.
The Chief Health Officer advises PrimeSafe on potential health risks. The article ‘Health risk assessment for cyanobacterial toxins in seafood’ estimates risk from seafood contaminated by cyanobacterial toxins, and provides guidelines for safe human consumption.
Toxins in seafood
Toxins in fish are concentrated in the internal organs. Fish should not be cooked with their guts intact, as this will just redistribute the toxin to the flesh. Fish that have been either filleted or gilled and gutted should be safe to eat or sell.
It is advised that other seafood (such as prawns, mussels and crabs) are not eaten during a bloom.
Health risk assessment - 2011-2012
The following table summarises the nodularin toxin guideline values for Gippsland Lakes seafood.
||Nodularin toxin guideline (micrograms per kilogram of whole organism)
Seafood samples are regularly collected from the Gippsland Lakes and tested for toxins. The following test results were obtained in 2011–12.