Algae grow almost everywhere in the world. They are a vital part of the aquatic ecosystem, providing food and shelter to other organisms. They play a crucial role in the ability of an aquatic ecosystem to absorb nutrients and heavy metals. In Australia there are at least 3000 freshwater species and we are still counting. One of the major algae problems in Australia is the increasing incidence of blooms of blue green algae. Certain blue-green algal blooms are toxic and algal toxins can seriously affect animals and humans. Toxic blue-green algal blooms cause a rash known as “swimmer's itch”, while powerful neuromuscular toxins released by other