IT STARTS SMALL, just a few cells cycling through the water column, invisible to the casual observer. But it’s not long before the proliferating blue-green algae, or cyanobacteria, become a bright green quagmire of deadly toxins.
Using gas-filled bags, the cyanobacteria - the oldest forms of life on Earth and the ancestor to modern plants - float towards sunlight to photosynthesise until the sugar-heavy cells sink back to the watery depths.
But at some point, usually between February and April, favourable conditions cause the cells to proliferate until those on top can’t sink and those beneath can’t surface. This internal war on the water surface manifests as a thick scum of cells resembling green sawdust or paint. With prolonged UV exposure, the cells die, releasing toxins, sucking oxygen from the water and killing any animal life unlucky enough to be in the vicinity.
This natural scourge afflicts every mainland state in Australia and causes an estimated $200 million of damage yearly. In an endless struggle against nature, scientists and water managers are developing better tools of detection, treatment and management of blooms, which experts predict will become even worse with the world’s changing climate.