waters. Factors including light, nutrients, and temperature can cause cyanobacteria to proliferate and form harmful blooms. Cyanobacteria blooms can cause hypoxia and produce high levels of toxins, impacting other aquatic organisms as well as causing illnesses in humans.

Some Cyanobacteria are capable of nitrogen fixation. The genus Anabaena uses specialized cells called heterocysts to physically separate nitrogen fixation and photosynthesis. Trichodesmium