Cyanobacteria (cyano=blue-green) are a type of algae found naturally in aquatic and terrestrial environments. Under the right conditions, cyanobacteria can grow rapidly resulting in an algal bloom. Environmental factors such as light, temperature, and nutrients contribute to bloom formation. Some of Florida's lakes, rivers, and estuaries have experienced cyanobacteria blooms, including Lake Okeechobee, Lake Apopka, and some parts of the St. Johns River. An algae bloom may appear green, red, purple, or rust-colored, sometimes resembling spilled paint. A bloom may be found on the water surface, below the surface, or mixed throughout the water column.
Health risks associated with cyanobacteria occur when people or animals are exposed to toxins that are sometimes produced by certain kinds of these organisms. Exposure can happen through unintentionally swallowing lake or river water, breathing water spray or coming into direct contact with the blooms. At high levels, these can affect the gastrointestinal tract, liver, nervous system, and skin. It is not possible to tell if a bloom is toxic by looking at or smelling the water. Therefore, it is recommended that people avoid contact with all algal blooms. Children and pets are especially vulnerable, so keeping them away from the water during a bloom is especially important.