Finally, HABs are not always produced by dinoflagellates and diatoms. Cyanobacteria, or blue-green algae, another group of single-celled organism, but one that is prokaryotic rather than eukaryotic, is also known to produce extremely potent toxins that can cause illness in fish, birds, and mammals including humans. Because of their potential to be harmful, this group is known as CyanoHABs.
Samples of CyanoHABsClick the images above to see full-size versions and complete source information.
Although the full scale of health effects of CyanoHABs on humans is not yet determined, the toxins may have gastrointestinal, respiratory, allergic and neurological responses, and potentially lead to liver damage. In addition, prolific growth of cyanobacteria can block sunlight, which can harm other organisms, and use up oxygen which can lead to hypoxia and anoxia. As in the case of the HAB dinoflagellates, the growth of CyanoHABs may be stimulated by nitrogen loading from agricultural industrial runoff, as well as sewage disposal.