A brief primer on blue-green algae
By Jeff St. Clair, WKSU
They’re probably the oldest living organisms on earth.
Fossils containing cyanobacteria, or blue-green algae, are more than 3.5 billion years old. Long before plants evolved, cyanobacteria perfected the energy producing process of photosynthesis, over time adding the oxygen to earth that made other life forms possible.
Scientists are still trying to figure out exactly how to classify them, but they are more closely related to bacteria than algae, hence the name cyanobacteria.
Not all blue-green algae is blue, green -- or toxic. The Red Sea gets its name from occasional blooms of a reddish species of Oscillatoria, and African flamingos get their pink color from eating Spirulina, which is also a dietary supplement for humans.
More than a dozen types of cyanobacteria produce chemicals that are toxic to humans and animals.
The best known is microcystis which produces its namesake microcystins. There have been approximately 60 different microcystins and all of the chemicals attack the liver in humans and animals.
The World Health Organization recommends levels of mycrocytins of less than 1 ppb, that’s part per billion of drinking water, or 1 ug/L (microgram per liter), but toxicity depends on the person. For example adults can probably handle more of the toxin than children, sick people or pregnant women.
The symptoms of microcystin poisoning include, skin irritation, stomach cramps, vomiting, nausea, diarrhoea, fever, sore throat, headache, muscle and joint pain, blisters of the mouth and liver damage.
Swimmers in water containing cyanobacterial toxins may suffer allergic reactions, such as asthma, eye irritation, rashes, and blisters around the mouth and nose.
The main cause of the current blue-green algae blooms is believed to be nutrient runoff from farm fields, lawns, gardens and septic tanks.
Phosphorus runoff is the main cause of concern for outbreaks of cyanobacteria. The shallow western end of Lake Erie is especially prone to toxic algae blooms because of the nutrients flowing from farms in western Ohio and Indiana.
Local, state and federal environmental groups are looking at ways to reduce farm runoff but these long-term solutions do little to prevent the toxic brew in the short term.
Researchers are learning more about the causes of toxic algae blooms, and some results point to a complex mix of ecology and pollution.
Blooms of cyanobacteria tend to reoccur in the same waters once they’re established and it’s difficult, if not impossible to eliminate them entirely.
Other research shows that invasives like zebra mussels contribute to cyanobacteria growth by releasing nutrients into the water column.A wet spring and summer have made conditions worse this year as nutrients flow off farm fields, down streams, rivers, and into Lake Erie.