This chapter is an introduction to the cyanobacterial (blue-green algae) ecology, with the main aim of better understanding the design of cyanobacterial blooms and cyanotoxins in the natural environments. Cyanobacteria are a diverse group of photoautotrophic organisms where their dominance represents a significant indicator of water quality. Several genera have the potential to produce toxins—hepatotoxins (microcystins, nodularins), cytotoxins (cylindrospermopsin), neurotoxins (saxitoxins, anatoxins, BMAA), dermatotoxins (lyngbyatoxin), and irritant toxins (lipopolysaccharide endotoxins). This chapter provides a concise and achievable summary of their negative impact on health and the environment, supplemented with tables and schemes that illustrate the ecology of cyanobacteria, the different types of cyanotoxins, and their health issues. The exposure routes are also discussed, which is particularly important due to the increasing eutrophication of water. It is emphasized that climate change, global warming, and increased eutrophication are responsible for cyanobacterial blooms. As a consequence, the risk they pose is likely to grow; accompanied by their ability to produce toxins, cyanobacteria represent an imminent danger to human and animal health. One of the primary goals of future research should be to share knowledge about cyanobacteria and cyanotoxins and to develop solutions for early detection and prevention of cyanobacterial bloom occurrence.

Cyanobacteria (blue-green algae) are a diverse group of photo-autotrophic organisms where their higher dominance, in favorable conditions, represents a significant indicator of water quality. Some of the cyanobacterial genera are toxigenic and can produce toxins—cyanotoxins, which influence animals and humans’ health, and also plants. Commonly known and studded cyanotoxin groups include hepatotoxins (microcystins, nodularins), cytotoxins (cylindrospermopsin), neurotoxins (saxitoxins, anatoxins, BMAA), dermatotoxins (lyngbyatoxin), and irritant toxins (lipopolysaccharide endotoxins). This chapter provides guideline values for the cyanotoxins in drinking water supply and in water for recreational purposes. This chapter focuses on a critical evaluation of the efficacy of water treatment procedures essential for cyanotoxin control. Such knowledge is extremely important in the future expansion of cyanobacterial toxic compounds from aquatic ecosystems, and according to the newest data, from terrestrial environments, especially due to climate change (global warming) and anthropogenic eutrophication. Here are introduced schemes of cyanobacterial ecology and infiltration of cyanotoxins through the biological cycle jeopardizing human health, and tables of the drinking water treatment, along with proposed therapy and limitations, setting the strong foundation for all future research, which are of outstanding scientific importance.