Uso de macroinvertebrados bentônicos como bioindicadores de qualidade da água da microbacia do córrego dos Palmitos, Orlândia-SP

Abstract

Aquatic ecosystems are impacted by diverse anthropogenic activities. In view of their preservation, it is necessary to monitor the quality of these ecosystems. In this sense, the objective of this study was to evaluate the water quality of the microbasin of the Palmitos stream by means of biomonitoring with benthic macroinvertebrates. The region accounts for 40% of the city's Orlândia-SP public water supply and is characterized by the absence of environmental studies. The environmental diagnosis of the stream of Palmitos and tributaries was carried out through the application of a Rapid Assessment Protocol (RAP), analysis of the metrics of the benthic macroinvertebrate communities, as well as physical and chemical analyzes of the water and sediment analyzes. The results of the RAP characterized the stream of the Palmitos ranging from altered to impacted and the tributaries from natural to altered. The biomonitoring, interpreted according to the BMWP, Shannon-Wiener, Pielou and Berger-Parker indices, characterize the water quality of the microbasin at different levels, from very poor to good, noting in the points closest to the urban area a high dominance of chironomids, mosquito larvae extremely resistant to environmental stresses. Most physico-chemical parameters did not present a strong correlation with the diversity of benthic macroinvertebrates. The high level of eutrophication of water bodies is highlighted due to the high concentrations of phosphorus from local agricultural activities, which cover about 60% of the area of the microbasin according to the study of land use and occupation. The analysis of the sediments showed that sites with more heterogeneity present a greater diversity of macroinvertebrates. In addition, the morphological characteristics of the microbasin contributed to the discussion of other analyzes, such as the granulometric analysis of the sediments. The protocol of functional feeding groups reveals an unstructured microbasin in the middle / low part, the predominance of collecting macroinvertebrates and the absence of fragmenters. These results, together, demonstrate the high degradability of the microbasin of the Palmitos stream in the region covered by the urban area, evidenced by the release of domestic effluents, the channeling of stretches of watercourses, among others. The results are expected to contribute to the strengthening of proposals for the monitoring and control of water pollution, serving as a subsidy for programs to recover degraded areas.