The diversity of benthic macroinvertebrates as an indicator of water quality and ecosystem health: a case study for Brazil

Abstract

The state of Minas Gerais still has some nearly pristine aquatic ecosystems, thus representing strategic aquatic resources for Brazil. Rivers and creeks of Serra do Cipó (19° -20°S, 43° -44°W) constitute an example of natural ecosystems in preserved conditions where a broad research project was initiated in 1996 aimed at the assessment of aquatic biodiversity and water quality characterisation. This area is the natural water division between the hydrographic basins of Doce and São Francisco rivers, two of the most important watersheds of Minas Gerais. The main goal of this study was to assess the diversity of benthic macroinvertebrate communities and use them as bioindicators of water quality. A secondary goal was to classify the benthic communities into three categories: 1) non-affected communities: those preserving a pristine structure, which are significant for fragile ecosystems, 2) median-affected communities: those receiving some degree of impacts, formed by a mixture of stenotopic and euritopic populations capable of adapting to new conditions thus reflecting the ecosystem's resilience, and 3) heavily-affected communities: those with very poor diversity, generally subject to severe human impact with destructive effects, but that are still important for the functioning of these degraded ecosystems.