Toxic blue-green algal blooms commonly occur in rivers and lakes throughout Australia. Blooms are most frequent when the weather is warm, which is also the time of year when many of us want to go for a swim in the outdoors. The public is notified of algal blooms at popular swimming holes, both on the managing authority's website and local signage. However, many people ignore the signs and jump in the water anyway. So how dangerous is it?
New research into blue-green algae suggests that they are more harmful than previously thought. Around 90% of cases of motor neurone disease have no known cause. Researchers at the University of Technology in Sydney have for the first time in 2013 established a clear link between blue green algae toxins and motor neurone disease. The breakthrough they achieved was to unlock the mechanism by which the toxins affect the human brain. It turns out to be a case of mistaken identity, with the toxins given access to our central nervous system because they have a similar structure to a healthy amino acid used to build essential proteins. More details about the research can be found at the university's website.
A blue green algae slick on the edge of Lysterfield Lake Park, Melbourne, a popular swimming venue
Motor neurone disease, sometimes also known as Lou Gehrig's disease, causes nerve damage that results in gradual muscle wasting, difficulties speaking and swallowing, and eventual death from respiratory failure within 1 to 5 years after diagnosis . It is not a disease that you want to take your chances with.
The level of exposure to blue-green algae that is required to trigger motor neurone disease is not currently known, and further research is needed. This health risk adds to the previously known risks of skin rashes, swollen lips, eye irritation and redness, ear ache and itchiness, sore throat, hayfever symptoms, asthma and possibly promotion of skin tumours, as per the Queensland Government Fact Sheet.
Pykes Creek Reservoir, west of Melbourne, looks inviting on a hot day, but is also an algal bloom hot spot
My advice is that if you see the algal bloom warning signs at a lake or river, stay out of the water and find another way to keep cool or exercise. Even better, head up to the mountains away from farmland and into a national park. There you can enjoy a swim in pristine waters where the only blooms you have to take notice of are the beautiful native wildflowers on the banks of the river.
The pristine waters of Moroka Gorge in the Great Dividing Range. No algal blooms here.