EVOLUCIóN DE LA CALIDAD DEL AGUA EN EL RíO NEGRO Y SUS PRINCIPALES TRIBUTARIOS EMPLEANDO COMO INDICADORES LOS íNDICES ICA, EL BMWP/COL Y EL ASPT

the aim of this study is to compare the results obtained in the study of negro river conducted in 2002 with those of 2007, using the bmwp / col, aspt, diversity (h') index and ica index, to reflect the evolution of the system over time, to understand the degree of change faced by different sections of the river as well as how the association structure of aquatic macroinvertebrates changes along the longitudinal gradient of the river associated with pollution. physicochemical variables show a trend towards improved conditions for water quality during the second sampling in each survey and longitudinal level is evidence of the resilience of the river. the variables with greater influence over the others were turbidity, total solids, nutrients, water temperature, and dissolved oxygen; however, they did not show relationship with the evaluated biological and chemical indices. the ica presented significant differences in the horizontal gradient, presenting a decline in the quality and macroinvertebrates biodiversity although an improvement in the conditions of the river between 2002 and 2007 was observed.