This breakdown process requires oxygen and can create a biological oxygen demand.Increases in biological oxygen demand result in decreases in oxygen concentration in the water, and this can adversely affect fish and other aquatic life, and can even result in fish kills.
The Wisconsin Department of Natural Resources is not currently conducting any routine monitoring for blue-green algae or blue-green algal toxins.
Blue-green algae, also known as Cyanobacteria, are a group of photosynthetic bacteria that many people refer to as "pond scum." Blue-green algae are most often blue-green in color, but can also be blue, green, reddish-purple, or brown.
Most algae are microscopic and serve as the main supply of "high energy" food for larger organisms like zooplankton, which in turn are eaten by small fish.
Small fish are then eaten by larger fish, and both small and large fish are eaten by mammals, raptors, and people.
Recent reviews of archived samples by DNR scientists have shown that Cylindro has been present in some southern Wisconsin lakes dating back to the early 1980s.
It is likely that migratory waterfowl brought this algae to Wisconsin and other Midwestern states.Scientists have recorded blue-green algae blooms dating back to the 12th century and they have documented the toxic effects to livestock for more than 100 years.However, it is possible that the frequency and duration of blooms are increasing in some Wisconsin waters as a result of increased nutrient concentrations.Cells may also be broken open when the water is treated with chemicals meant to kill algae, and when cells are swallowed and mixed with digestive acids in the stomachs of people or animals.The only way to be sure if the toxins are present is to have water samples analyzed in a laboratory using sophisticated equipment. Fossil evidence suggests that blue-green algae have been around for millions of years.When the cells are broken open, the toxins may be released.