Under certain environmental conditions (light, temperature,
pH), and the eutrophication due to the abundance of nutrients, particularly
phosphorus and nitrogen, these organisms can grow on a
large scale to produce blooms. Although these blooms can appear
in any season, most of the studies carried out have concluded that
environmental conditions are best for growth at the end of summer
and the beginning of autumn. Their life-span ranges between
2 and 4 months, although they can persist for a long time in some
warm and subtropical regions (Chorus and Bartram, 1999). Sometimes,
blooms produce toxins (cyanotoxins) from the secondary
metabolism (Duy et al., 2000).