Abstract
Score-based biotic indices are widely used to evaluate the water quality of streams and rivers. Few adaptations of these indices have been done for South America because there is a lack of knowledge on macroinvertebrate taxonomy, distribution and tolerance to pollution in the region. Several areas in the Andes are densely populated and there is need for methods to assess the impact of increasing human pressures on aquatic ecosystems. Considering the unique ecological and geographical features of the Andes, macroinvertebrate indices used in other regions must be adapted with caution. Here we present a review of the literature on macroinvertebrate distribution and tolerance to pollution in Andean areas above 2,000 masl. Using these data, we propose an Andean Biotic Index (ABI), which is based on the BMWP index. In general, ABI includes fewer macroinvertebrate families than in other regions of the world where the BMWP index has been applied because altitude restricts the distribution of several families. Our review shows that in the high Andes, the tolerance of several macroinvertebrate families to pollution differs from those reported in other areas. We tested the ABI index in two basins in Ecuador and Peru, and compared it to other BMWP adaptations using the reference condition approach. The ABI index is extremely useful for detecting the general impairment of rivers but class quality boundaries should be defined independently for each basin because reference conditions may be different. The ABI is widely used in Ecuador and Peru, with high correlations with land-use pressures in several studies. The ABI index is an integral part of the new multimetric index designed for high Andean streams (IMEERA).
Highlights
Working Party (BMWP) in the United Kingdom (Armitage et al, 1983)
To make the final selection of taxa for our adaptation of the BMWP index, we focused on studies that included macroinvertebrate taxa listed together with data on water quality from the Andean regions of Colombia, Ecuador, Peru and Bolivia
Delimiting a high Andean fauna: In the analysis of published data, we found four versions of the BMWP currently in use in our target region: the original BMWP, the adaptation for the Iberian Peninsula (IBMWP), the adaptation for Antioquia, Colombia (BMWPA), and an adaptation for Chile (CHBWMP)
Summary
Working Party (BMWP) in the United Kingdom (Armitage et al, 1983). This index gives a score to each taxa (mostly families) according to the sensitivity of pollution (mainly organic), being the most sensitive taxa scored with values of 10 and the less sensitive (or more resistant) to pollution a score of 1. Many areas of the Andes are densely populated; as a result, there is an urgent need for methods to assess water quality in these regions in an effective and affordable way In this regard, the BMWP index is useful because of its simplicity. The ABI is already in use as part of the CERA (Calidad Ecológica de Ríos Altoandinos, Ecological Quality of High-Andean rivers; Acosta, Ríos-Touma, Rieradevall & Prat, 2009). This is the first time the index is described and tested
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