Selection of macroinvertebrate metrics for rapid assessment of the human impact by biotic conditions of Bolivian Altiplano streams

We developed a rapid multimetric index using macroinvertebrates as bioindicators of ecological conditions for the Bolivian Altiplano streams. A total of 64 taxa and 30 environmental variables were collected from 29 sampled sites. After identifying redundant metrics through Principal Components Analysis (PCA) and considering practical application criteria, four biological attributes were selected to compose the Altiplano Integrity Benthic Index (AIBI): Genus richness, Filter-Collector, Gatherer-Collector, and Swimmer groups. The sensitivity of the index was tested in 17 rivers using a Co-Inertia Analysis (CoIA), and its first axis of analysis was strongly correlated to the new AIBI scores (r = 0.8, p < 0.001). At Pacajes Rivers, the macroinvertebrate Gatherers-Collector group was common in organic pollution sites and the Swimmer group with hydraulic disturbance sites. In contrast, the Scraper group becomes a specific group for the reference conditions. The AIBI responded to environmental variables associated with a gradient of human disturbance affecting the running freshwater's ecological condition. The proposed index could allow the structuration a biomonitoring program.