ARE BLUE-GREEN ALGAE AND CYANOBACTERIA THE SAME THING?

Cyanobacteria were previously grouped with algae but are now classified as bacteria after analysis of cell structure and cell division. They differ from other bacteria in that they contain photosynthetic pigments similar to those found in algae and plants. Although they are predominantly photosynthetic (light-dependent) organisms, they are also capable of a using organic compounds as a source of energy. Some cyanobacteria have a specialized structure called a heterocyst that can fix molecular nitrogen. The ability to fix nitrogen gives these species a competitive advantage over other algae. Many cyanobacteria have gas vacuoles that allow them to remain in suspension and migrate to surface waters where there is plenty of light for photosynthesis. On the surface, colonies may clump together and form a scum which can cause water quality problems in lakes.

Can cyanobacteria make you sick? Yes. People may develop allergic reactions such as skin rash, hives, itchy eyes and throat if they come in contact with water containing cyanobacteria that are producing toxins. Swimming, water-skiing, and wind surfing are examples of recreational activities during which dermal exposure to toxins may occur. Some symptoms caused by cyanobacteria exposure may be similar to those caused by swimmers itch, a condition that has been reported among bathers in many Washington lakes. Swimmers itch may occur on any exposed skin and can cause a sharp burning and itching in affected areas. Small reddish bumps surrounded by a zone of redness may appear within twelve hours after swimming. Itching due to swimmers itch is intense.

If you come in contact with water containing blue-green algae toxins or swimmers itch, rinse off your body as soon as possible. Long-term exposure to water with microcystins has been shown to promote liver tumors in animals. For this reason, people and animals should not drink water from a source with a cyanobacterial bloom. It is possible for more severe illness to occur if cyanobacterial toxins are swallowed. Consult a physician if someone ingests water with cyanobacteria and has any of the following symptoms: stomach cramps, vomiting, diarrhea, fever, headache, and severe muscle or joint pain. If someone shows signs of seizure or convulsions after swimming or drinking water where cyanobacteria are present, they should seek immediate medical attention.

Although the term blue-green algae is still in common use, these organisms are no longer classified as algae at all, but as a type of photosynthetic bacteria (cyanobacteria) that rely on sunlight for energy. They are one of the oldest forms of life still thriving on earth. There are a number of questions and answers in this database that refer to both blue-green algae and cyanobacteria.