Expansion of alien and invasive cyanobacteria

Biological invasion is a broadly debated phenomenon, but a unified model or concept for the invasion processes of microorganisms and macroorganisms has not been defined. There are many terms associated with biological invasions, including "invasive," "exotic," "nonindigenous," "alien," or "non-native" species, sometimes used synonymously, to signify that a species is outside of its native range. Several definitions related to biological invasions and the invasive species concept in cyanobacteria are proposed in this chapter. Examples of invasive and alien cyanobacteria, including Cylindrospermopsis raciborskii, Chrysosporum ovalisporum, Sphaerospermopsis aphanizomenoides, Chrysosporum bergii, Dolichospermum lemmermannii, Nodularia spumigena, and Raphidiopsis mediterranea, are discussed. This chapter also summarizes key information on physiological and environmental factors enhancing the expansion of alien cyanobacteria and the impact of their invasion on ecosystems.