In the 1977 site, Pyrocystis sp., Cladophora sp., and Coscinodiscus lacustrisnin were the least abundant while Placodem desmid, and Histioneis remora (in the 1988 site), and Spirogyra longata, Euglena sp. and Ulothrix sp. (in the 2004 site) were the least abundant species in those sites. The most frequent species were Nitzschia seriata, Chlorella sp. and Cyclotella menghirians, present in the 1975 and 1977 sites. Euglena sp. was more frequent in the 1977 and 2004 sites, and Peridium sp. is present in the 1988 and 2004 sites. The least frequent species were Ulothrix sp. and Podolampas sp. which were present only in the 2004 site.