Unpredictable poisonings of livestock and wildlife by waterblooms or scums of freshwater cyanophytes occvir when toxic strains of the common specie? dominate composition sufficiently to provide above-threshold levels of toxins by susceptible animals.Known toxins produced from freshwater cy?.nopKytes are alkaloids, polypeptides ^pteridines or lipopolysaccharide-New toxins produced by new strains have, been described recently.Freshwater cyanophyte waterblooms can cause allergic reactions and, in water supplies, are suspected of causing outbreaks of human gastroenteritis.