Biological quality of waters from an impacted tropical watershed (middle Rio Doce basin, southeast Brazil), using benthic macroinvertebrate communities as an indicator

Taking the watershed as the unit for intervention and conservation, in this study we assess water quality along a stretch of impacted watershed of considerable economic importance, the middle Rio Doce basin, using the benthic macroinvertebrate community, along with physical and chemical characteristics as parameters, for the classification of 20 sampling stations. The results showed that parameters often used in temperate regions are also useful to assess water quality in tropical ecosystems, where no specific methodology has yet been developed. In spite of a clear distinction between stations of good and bad quality, the multimetric biological analysis alone was not sensitive enough to identify intermediate conditions. Grouping similar and dissimilar stations by Cluster analysis of physical and chemical variables and biological data, however, it was possible to distinguish three categories based on the biological quality of the water: (1) stations With poor quality waters (2) stations with high quality water, and (3) stations with water of intermediate quality. Classifications of water quality of this sort will hopefully assist decision-makers in defining restoration/conservation strategies, and will provide an important tool for monitoring biodiversity and water quality in tropical watersheds.