Avaliação biológica e ambiental de nascentes da bacia hidrográfica do Ribeirão da Onça em Elói Mendes, Minas Gerais, Brasil

Abstract

Although the research carried out in the Ribeirão da Onça hydrographic sub-basin has been reporting degrading activities in spring areas since 2003, but there is no record of aquatic fauna done so far. Considering the accelerated context of degradation, knowledge of the species for biodiversity records is urgent, so that, for exemple, biomonitoring activities can happen. In this dissertation we aimed to assess the biodiversity and conservation status of the Ribeirão da Onça sub-basin and region, and the results are divided in two scientific manuscripts. The first manuscript aims to evaluate the degree of preservation and water quality of ten springs in the sub-basin using the Environmental Impact Index of Springs (IIAN) and the biotic indices BMWP' and ASPT. The results reveal that none of the springs observed is in an excellent state of preservation and that their water is polluted or heavily polluted. At the second manuscript we performed a survey of zooplankton and benthonic macroinvertebrates in the same ten springs, and verified which spatial and environmental factors influenced the composition of organisms in these environments. A total of 4,197 individuals belonging to 7 classes were sampled. The taxa that showed the highest abundance and were sampled at all collection points were Diptera/Chironomidae, Copepoda/Cyclopoida and Ostracoda/Candonidae. The results showed that the composition of the zoobenthic communities is mainly determined by environmental characteristics, but for organisms such as zooplankton, which are poor dispersers, spatial variables werealso decisive. Based on the results presented, we indicate the need to increase efforts to preserve springs, in order to guarantee the quantity and quality of water and to maintain the region's biodiversity.