The influence of land use on water quality and macroinvertebrate biotic indices in rivers within Castilla-La Mancha (Spain)

With the objective to determine the influence of land use on the quality of the fluvial ecosistms within Castilla-La Mancha, Spain, physicochemical variables (conductivity, concentrations of ammonium, nitrite, nitrate, phosphate) and various benthic invertebrates indices (IBMWP, BMWQ and MCLM) Were Measured. In total, 82 stretches of rivers belonging to the Tajo, Guadiana, Jucar and Segura watersheds were sampled during the summer of 2001. The percentage of every land use type on a regional scale (drainage area) was calculated, obtained from the CORINE Land Cover and tools from ArcGIS 9.0 software. The correlation analysis results showed it significantly strong relationship between nutrients and biotic indices and the urban. forested and dry agriculture uses. For irrigated agriculture. low Correlations were found for nutrients (nitrate and phosphate) and biotic indices. Given the importance of agriculture in the Castilla-La Mancha Region (53 % of the area) and the effects on the fluvial ecosystems, this Study highlights the need for improved wastewater treatment, its well its good agricultural management practices and the maintenance of the riparian corridor.