Cyanobacteria Occurrence in Photosynthetic Stabilization Ponds

Photoautotrophic organisms, particularly cyanobacteria, have great ecological importance due to their photosynthetic capacity, and biosynthetic versatility in diverse and extreme environments. However, photosynthetic ponds, they may be serious and dangerous producers of potentially toxic toxins. Their release and bloom in treated effluent receiving bodies are a major concern because of the negative consequences on aquatic biota and the risks to public health. The aim of this study is to analyze the occurrence, composition, density and spatio-temporal distribution of cyanobacteria in sewage treatment plants by photosynthetic ponds in ten cities located in the central region of the São Paulo State, Brazil. The results recorded high densities of Microcystis sp. with a maximum average of 9.4x105 cells per millilitre (cells/mL); Synechococcus sp., with an average of 7.8x105; Synechocystis aquatilis with 7.2x105; Merismopedia tenuissima with 4.8x105; and Phormidium sp. with 1.9x105. Among these species found, the highest occurrence was M. tenuissima. The high densities show that these ponds are an aquatic environment conducive to the development of cyanobacteria and, potentially, an important source of cyanotoxin production. Therefore, studies and monitoring of the effects on the receiving water bodies are recommended by determining their cyanobacteria densities and investigating the possible presence of cyanotoxins.