AIM: This work presents the results of the first water quality assessment using the biotic index Índice Biótico Estendido - Instituto Oswaldo Cruz (IBE-IOC) for 1st to 4th order streams in the Serra dos Órgãos region, Rio de Janeiro State, Brazil. The aims were to evaluate the sensitivity of IBE-IOC, verifying its ability to assess anthropogenic impacts over the stream gradient and along the year; METHODS: The sensitivity of the index was evaluated according to the degree of interquartile overlap in Box-and-Whisker plots; RESULTS: The index is able to distinguish different types of environmental integrity and different impacts by deforestation and organic pollution; CONCLUSIONS: Our results supported the recommendation of IBE-IOC as a useful tool for water quality assessment of wadeable streams in this region.
bioindicators; macroinvertebrates; River Guandu; Atlantic Forest; Rio de Janeiro