Biomonitoramento da qualidade de água dos rios Leãozinho e Ligeirinho, Erechim,RS: abordagem integrada através de parâmetros biológicos, físico-químicos e microbiológicos,

Abstract

Aquatic ecosystems have been altered as a result of environmental impacts caused by human activities. In this sense, the preservation of water bodies is an alternative to ensure the sustainability of natural resources. Studies on the limnic ecosystems are important in the development of actions to preserve aquatic biodiversity and maintain the ecological integrity of these water bodies. This study aimed to evaluate the water quality of the Leãozinho and Ligeirinho Rivers, used for public supply. The works that make up this thesis are divided into two chapters. The evaluation carried out in the rivers by biomonitoring with benthic macroinvertebrates, physicochemical and microbiological parameters showed good quality water in most of the results, fitting in Classes 1 or 2 of Resolution number 357/05 of CONAMA. The analysis made through the organic index BMWP’ showed that the Leãozinho and Ligeirinho Rivers basins have reduced water quality, suffering from impacts such as the removal of riparian vegetation, agriculture practice on its banks and contribution of urban and animal waste. The evaluation by the protocol proposed by Callisto et al. (2002) allowed to relate disturbed habitats with the greatest abundance of the trophic group gatherers-collector, especially on stretches with no riparian vegetation. The results of the structure index of the benthic community showed decrement in the environmental quality of streams, given the representativeness of dominant and tolerant families to moderate pollution. The Ephemeroptera, Plecoptera and Trichoptera groups were representative in the stretches of Leãozinho and Ligeirinho Rivers, being related to environments with stream and bedrock. Biological monitoring of water is an essential factor to determine the quality and the treatment to be done aiming a more efficient management, recovery of degraded environments and preservation of the least changed locations. The insertion of geological and climate studies are suggested, aiming the building of regional evaluation parameters. Such actions are necessary in order to guarantee the environmental quality and the water quality of these watersheds, preventing public health problems and enabling the maintenance of the aquatic biota.