Evaluation of cyanobacteria toxicity in tropical reservoirs using crude extracts bioassay with cladocerans.

During a cyanobacterial bloom in a eutrophic environment, particularly at the end when decomposition occurs, toxic compounds such as the cyanotoxins and the lipopolysaccharides can be released in high concentrations into the water column damaging aquatic organisms. In this work, the effects of this release of toxic compounds during a cyanobacterial bloom were investigated. The acute and chronic toxicity of cyanobacterial crude extracts from two natural blooms in the Barra Bonita and Ibitinga reservoirs (Middle Tietê River, São Paulo State, Brazil) and of a toxic strain cultured in the laboratory were tested.

Water quality assessment by ecotoxicological and limnological methods in water supplies, southeast Brazil.

The quality of the water supplied to Araraquara city (São Paulo State, Brazil) was analyzed at four points: two reservoirs from which water is pumped and the water incoming and exiting a drinking-water treatment plant. Physical and chemical analyses of water were performed, as well as acute and chronic toxicity tests of the water from all four points, using Ceriodaphnia silvestrii (Cladocera, Crustacea) as test-organism. The study was carried out monthly in the period between December 2000 and November 2001.