EVALUACIÓN DE LA CALIDAD DEL AGUA Y DE LA RIBERA EN DOS CUENCAS TRIBUTARIAS DEL RÍO TUXCACUESCO, JALISCO, MÉXICO

Abstract

It has been documented that in Mexico 80% of aquatic ecosystems, including water bodies such as rivers, are under some degree of contamination. It has been detected that the main pollutants are organic matter, nutrients (nitrogen and phosphorous) and microorganisms (faecal coliforms). Addressing this problem is of vital importance for the conservation of aquatic ecosystems and for improving the quality of life of the inhabitants of the surroundings. In this sense the lack information on the quality status of aquatic ecosystems in the Tuxcacuesco river basin, in the satate of Jalisco, is very scarce and non-existent for its tributary basins. Therefore, in the present study the objective was to infer the quality of the aquatic ecosystems of two tributary basins (Tonaya and Apulco) of the Tuxcacuesco river, in Jalisco, Mexico, by using two indices. The first an index of biotic integrity based on the presence or absence of families of aquatic macroinvertebrates, and the second an index to assess the ecological status and quality of riverbanks, the riverbank quality index (RQI). Two samplings were carried out at four sites, in the month of October 2015 (end of the rainy season) and February of the year 2016 (beginning of the dry season), in which aquatic macroinvertebrates were collected and the RQI index was applied. In addition, physical and chemical parameters (pH, electrical conductivity and flow rate) were evaluated and the total nitrogen content was determinated in each site. By means of a canonical correspondence analysis, it was evidenced that the flow and the electrical conductivity are the environmental variables that have the greater relation with the order of the families of macroinvertebrates found. In general, the ecological status of the banks is poor in the two tributary basins, and the nitrogen content in the waters exceeds the permissible limits for potable use and agricultural irrigation. Regarding the application of the biotic integrity index, it was found that in most of the sites there is the presence of organic contamination.