Anthropogenic impacts on rivers: use of multiple indicators to assess environmental quality status

The effects of urban growth are multidimensional and therefore they cannot be assessed using only one indicator. The objective of this study was to assess the environmental quality of urbanized rivers through the evaluation of multiple indicators, including water quality, habitat condition, macroinvertebrate assemblages, and anuran amphibians as bioindicators. Twelve sites along three rivers were characterized regarding water quality and habitat condition using a Habitat Model Affinity score, during high-flow and low-flow seasons between 2009 and 2013. Fourteen water quality parameters were assessed at each site. A general Water Quality Index was applied to the physical, chemical, and bacteriological data. Macroinvertebrate taxa richness, Plecoptera–Ephemeroptera–Trichoptera richness, and the Biotic Index of San Luis Sierras were the metrics used to analyze macroinvertebrate assemblage shifts. Species richness and relative abundance of amphibians were estimated from calling and visual encounter surveys, in parallel with all aforementioned parameters. Principal Component Analysis identified that macroinvertebrate-based metrics were superior in reflecting the water quality and habitat condition impairments, whereas amphibian metrics showed a differential sensitivity to specific water quality parameters such as nutrient enrichment. This study contributes to achieve a more comprehensive understanding of the complexity of the chemical and biological processes experienced by urban affected environments.