Blue-green algae is not actually algae, but a type of bacteria called cyanobacteria. It is harmful to livestock and humans when it produces toxins, which happens as the cyanobacteria dies off. These toxins can attack the liver and nervous system and cause sickness or even death. Some common signs that an animal has ingested these toxins include staggering, gastroenteritis, convulsions and difficulty breathing.
Blue-green algae typically forms in nutrient-rich fresh water sources when daytime temperatures are warm or hot. It can start forming in June and can occur throughout the summer.
There are many species of blue-green algae that can take on different appearances. It can look like a blue-green shimmering paint across the water’s surface, it may look like pea soup or it could also look like grass clippings floating in the water (among other forms). One way to help identify if it is blue-green algae is to do the “finger test”: if you scoop your hand through the water and the algae does not clump up on your hand (meaning it is filamentous or strand like) but instead it flows through your fingers, it is likely blue-green algae.
It is difficult to get a lab test to confirm the presence of blue-green algae in a water body so controlling the growth becomes very important. This can be done through the treatment of a water body with existing blue-green algae growth or through prevention of growth in the first place.