Hongos y algas como indicadores de la calidad del agua de un arroyo urbano.

This study evaluated the response of anamorphic fungi and biofilm algae to changes in physicochemical variables of water quality. Samples were taken at five sites of the Gutiérrez stream, located in the vicinity of Luján city (Buenos Aires Province, Argentina), a system affected by effluents from textile industries. The samples were taken at five sampling sites: two upstream sites and three sites downstream the effluent. Samples for the study of physicochemical variables (dissolved oxygen, temperature, pH, conductivity, nitrates, ammonium, chlorides, BOD, COD), as well as samples of algal biofilms developing on submerged substrates, and fungi developing on litter were collected from each site. In the case of the algae, fluorometric measurements were done to estimate biomass, production and photosynthetic efficiency. The relative and total abundances of the groups present were evaluated through microscopic observations. Regarding fungi, the species present in the different sites were determined and the sporulation rate and activities of three enzymes were evaluated. These indicators were useful to point out polluted areas, and in particular the biological indicators also showed recovery areas. The most important chemical variables indicating contaminated areas were ammonia, phosphates and COD concentration. The species of aquatic fungi were very indicative, particularly the abundance of species compared to the first site. Regarding algae, the highest sensitivity to contamination was detected through chlorophyll and minimum fluorescence (Fo). Other indicators such as sporulation rates, enzymatic activities and algae groups, provided complementary information to evaluate the state of the stream, and were sensitive to diffuse and point contamination. The application of chemical and biological indicators is recommended to increase the sensitivity of water quality analyses and to evaluate the effects of pollution. [ABSTRACT FROM AUTHOR]