Abstract

A healthy body of freshwater can provide numerous benefits to the society, although currently, the degradation of such ecosystems has been increased due to the establishment of urban areas along its riverbanks. In this study we analyzed the spatial effect of these zones on the water quality, using the benthonic macroinvertebrate communities as bioindicators of fluvial contamination in the Gibbs channel of the Temuco commune (38°46°'S 72°38°'W). The samplings were performed in spring, in six sites. The macrozoobentos was composed by a total of 15 taxa, corresponding to organisms tolerant to anoxic conditions and high concentrations of organic matter, such as amphipods (Hyalella), dipterans (Quironomidae), and oligochaetes (Oligochaeta). There was a marked difference in the composition and abundance of taxa between the pre-urban, urban, and post-urban areas (ANOSIM Global R = 0.882, p = 0.001) tendency that was also recorded by the physicochemical parameters (ANOSIM Global R = 0.498, p = 0.001), of which pH, total suspended solids, and dissolved oxygen are those that best explained the patterns observed in the macrozoobentos. The results obtained with the biotic family index (ChIBF) were similar to those registered in the lower parts of the basins of southern Chile and the invertebrate community was shown to be sensitive to anthropogenic disturbances. © Asociación Ibérica de Limnología, Madrid.