Avaliação da influência do uso e ocupação do solo na qualidade da água utilizando bioindicadores

Abstract

Aquatic ecosystems have been significantly altered by several environmental impacts from anthropogenic activities. In this context, an integrated assessment of the ecological effects caused by multiple sources of pollution and benthic macroinvertebrates has proved to be efficient. Thus, the objective of the study was to evaluate the environmental quality of the micro-basins of Lanoso and Mangabeiras (Uberaba-MG) as a function of soil use and occupation using bioindicators. BMWP, functional trophic groups (GTF), indexes of diversity, equitability and dominance, physical-chemical analysis, application of Rapid Assessment Protocol and GIS to map land use and occupation were used for this evaluation. It was observed that less altered places had higher BMWP, greater diversity and equitability, and lower dominance. The most altered presented smaller BMWP, diversity and equitability and, greater dominance of organisms tolerant to the pollution. The GTF assessment was also compatible with water quality, indicating greater diversity and distribution for preserved environments, and the evident dominance of groups tolerant to pollution and less diversity in more altered environments. There was a decrease in water quality from the rainy season to drought, usually accompanied by decay in the biological and statistical indexes of ecological diversity, lower diversity of functional groups and evident predominance of tolerant groups. The progressive decay of water quality observed upstream and downstream in both microbasins presented a moderate negative correlation, by the Spearman coefficient, with an increase in the environmental degradation of the PPAs in the springs and a moderate positive with the percentage of the microcatchment area occupied by Agriculture. Progressive water quality decay observed from L1 to L3 in the Lanoso microbasin and from M1 to M2 in the Mangabeiras microbasin was perceptible. The water quality decay in the upstream-downstream direction is closely related to the state of conservation of the PPAs of the sources that supply the respective tributaries where the macroinvertebrates were collected. Those that had the contribution of springs with good state of conservation had higher biotic indexes and as there was increase in the degradation of the PPPs, a decrease in water quality was registered.