Title: Epilithic diatoms as indicators of water quality in Upano River, Ecuador

Authors: Patricio Méndez-Zambrano; Rogelio Ureta; Luis Tierra; Ángel Flores

Addresses: Department of Environmental Engineering, Escuela Superior Politécnica de Chimborazo (ESPOCH), Morona Santiago, 140101, Ecuador; Department of Hydraulic and Environmental Engineering, Universidad Politécnica de Valencia, Valencia, 46022, Spain ' Department of Environmental Engineering, Escuela Superior Politécnica de Chimborazo (ESPOCH), Morona Santiago, 140101, Ecuador ' Department of Environmental Engineering, Escuela Superior Politécnica de Chimborazo (ESPOCH), Morona Santiago, 140101, Ecuador ' Department of Information Technology, Escuela Superior Politécnica de Chimborazo (ESPOCH), Morona Santiago, 140101, Ecuador

Abstract: This study evaluates the impact of urbanisation and agriculture on the water quality of the Upano River, using epilithic diatoms as bioindicators. Six sampling stations were analysed during summer and winter, measuring physicochemical parameters and diatom diversity. Thirty-six species were identified, with dominant genera such as Navicula (34.03%), Ulnaria (9.67%) and Encyonema (8.90%). Water quality index (WQI) values ranged from 72.14 (good quality) to 31.79 (poor quality), evidencing a pollution gradient related to human activities such as cattle ranching and mining. Trophic classification indicated oligotrophic conditions in the higher stations and eutrophication in the lower zones. Principal component analysis showed that phosphorus, nitrates and biological oxygen demand (BOD) were determinants of water quality variation. The results underline the value of biological indices to complement physicochemical measurements and improve water resource management. It is recommended to integrate multidisciplinary approaches for the conservation of aquatic ecosystems.

Keywords: aquatic bioindicators; ecological assessment; freshwater ecosystems; species richness; phytoplankton.

DOI: 10.1504/IJW.2026.153223

International Journal of Water, 2026 Vol.17 No.3, pp.270 - 285

Received: 17 Apr 2024
Accepted: 16 Mar 2025
Published online: 29 Apr 2026 *

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