Applicability of borrowed diatom-based water quality assessment indices in streams around São Carlos-SP,Brazil

Diatom-based indices are increasingly becoming important tools for the assessment of ecological conditions in lotic systems. The applicability of regional and foreign diatom-based water quality assessment indices to streams around São Carlos-SP, Brazil, is discussed. The relationship between measured water quality variables and diatom index scores was assessed. The indices, when compared to chemical analyses, proved useful in providing an indication of the quality of the investigated waters. Though all borrowed indices were applicable to the study area because many widely distributed diatom species have similar environmental tolerances to those recorded for these species elsewhere, ecological requirements of some diatom species from Brazil need to be clarified and incorporated in a diatom-based water quality assessment protocol unique to the region.