Blooms of toxic cyanobacteria in freshwater in algeria

Abstract

When water temperature and irradiance as well as meteorological conditions and nutrient supply are favourable, cyanobacteria can flourish in lakes and rivers where they can produce blooms usually in summer to late autumn, in both subtropical and temperate latitudes. Several of which are toxic and produce specifically hepatotoxins type microcyst ins. Studies undertaken in dams and natural lakes, particularly in the lake Oubeira and the dam Cheffia (East-Algeria), showed that these media evolve quickly to eutrophication, following an increased productivity stimulated continuously by the fertilizer contributions and a change of increasingly dry climate. The appearance of toxic cyanobacteria in these water bodies either used as drinking water or for recreational purposes may present serious health risks for the human population. The biodiversity of toxic cyanobacteria and their toxins, undertaken in the lake Oubeira and the dam Cheffia, showed that the Microcystic is the most implied genus in the formation of cyanobacterial blooms. The concentrations of microcyst ins, estimated by the PP2A method, are very high (28 mg/L) during the period of cyanobacterial blooms in summer and at the beginning of autumn. The MC-LR, MC-YR, and MC-RR are the most common microcyst in congeners identified in these water bodies.