Castillejo, PabloOrtiz, SofiaJijón, GabrielaLobo, Eduardo A.Heinrich, CarlaBallesteros Redondo, María IsabelRíos Touma, Blanca2025-05-052025-05-052023-07-12Castillejo, P., Ortiz, S., Jijón, G., Lobo, E. A., Heinrich, C., Ballesteros, I., & Rios-Touma, B. (2024). Response of macroinvertebrate and epilithic diatom communities to pollution gradients in Ecuadorian Andean rivers. Hydrobiologia, 851(2), 431-446. https://doi.org/10.1007/S10750-023-05276-60018-815810.1007/s10750-023-05276-6https://hdl.handle.net/20.500.14352/119802This study was performed under project numbers IBR.BIO.19.05 and AMB.BRT.22.01, financed by Universidad de Las Américas, Ecuador.Population growth and increasing production demands threaten the highly diverse Andean freshwater ecosystems. Biological indicators constitute a valuable tool for evaluating the ecological quality of freshwater ecosystems under different pressures. Diatom and macroinvertebrate assemblages are the most used bioindicators to assess water pollution, whereby these biotic groups occupy the first and second trophic levels and respond to habitat pollution. Several studies have explored the response of these communities to water pollution in other regions, but no studies have examined their performance in Andean rivers. In this context, this research aimed to evaluate the responses and relationships of both groups of bioindicators in the Upper Guayllabamba basin. We collected macroinvertebrate and diatom samples from nine sites in this basin during the dry and wet seasons, calculated trophic indices for both groups, and related them to environmental characteristics. The results indicated that both bioindicators were sensitive to changes in land use and nutrients. Epilithic diatoms were more sensitive to changes in water chemistry and macroinvertebrates to changes in fluvial habitat and land use. The index based on macroinvertebrates better-detected changes in quality classes between sites and seasons. Therefore, both indices gave complementary information, and their joint use seems suitable in Andean streams.engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/journal article1573-5117https://doi.org/10.1007/s10750-023-05276-6https://link.springer.com/article/10.1007/s10750-023-05276-6open access574.5591.524:592502.51504.5Biotic indexesAndean streamsPeriphytonAquatic insectsEcología (Biología)InvertebradosMedio ambiente natural2508.05 Hidrobiología2401.06 Ecología Animal2401 Biología Animal (Zoología)2401.17 Invertebrados3106.01 Conservación