Cyanobacteria that produce algal blooms have become increasingly toxic to fish and plants according to research published in the Oct. 25, 2013, issue of the journal Science by scientists from Oregon State University and the University of North Carolina at Chapel Hill.
Cyanobacteria that produce toxins populate about 33 percent of all the lakes in the United States that are larger than 10 acres in size according to the last EPA National Lakes Assessment. Cyanobacteria of many species form the green scum on lakes and in the ocean. Toxic species of cyanobacteria are replacing species that are not toxic.
One of the most common toxins produced by cyanobacteria that are toxic is a potent liver toxin and may be carcinogenic. Toxicity is conferred by the amino acid microcystin. The majority of known species of cyanobacteria are capable of increasing levels of microcystin as a protection against oxidative stress.
Dams, rising global temperatures, rising carbon dioxide concentrations, droughts, and increased runoff of nutrients from urban and agricultural lands are causing Cyanobacteria to develop increasing toxicity to other life over time in order to survive. Cyanobacteria are extremely adaptive and almost impossible to eradicate.
Cyanobacteria are one of the oldest known life forms on Earth dating back about 3.5 billion years. There was minimal oxygen available at that time and the researchers conclude that cyanobacteria were not originally toxic to other life forms.