Integrated Hydrobiological Monitoring of Water Quality in the Oued Guigou River (Timahdite, Ifrane, Morocco): Application of Multi-Indicator Approaches and Multivariate Statistical Analysis

The present study assessed the ecological status and water quality of the Oued Guigou River (Timahdite, Ifrane, Morocco) using an integrated approach combining physicochemical, hydrobiological indicators, and multivariate statistical analyses. Five sampling stations were monitored from June 2025 to May 2026 to evaluate the spatial and temporal variability of river water quality. Physicochemical parameters, including temperature, pH, conductivity, dissolved oxygen, biological oxygen demand, nitrates, phosphates, and water quality index were analyzed in conjunction with biological indicators such as taxonomic richness, Shannon–Wiener index, Evenness index, and Biological Global Normalized Index. Multivariate statistical approaches, particularly Principal Component Analysis and Hierarchical Cluster Analysis, were applied to explore the relationships between environmental variables and macroinvertebrate assemblages. The results revealed a clear longitudinal degradation of water quality from upstream to downstream stations. Upstream stations exhibited good to excellent ecological status, characterized by elevated dissolved oxygen concentrations and higher macroinvertebrate diversity, as evidenced by increased values of biological indices, with communities dominated by pollution-sensitive taxa. In contrast, downstream stations showed elevated nutrient concentration, reduced biological diversity and increasing dominance of pollution-tolerant taxa, reflecting poor to very poor ecological quality. These patterns were attributed to agricultural runoff and cumulative anthropogenic pressures. Multivariate analyses demonstrated strong correlations between hydrobiological indices and physicochemical parameters, confirming the sensitivity of macroinvertebrate assemblages to organic pollution. Furthermore, biotypological classification identified five major ecological groups based on environmental variables and seasonal characteristics. Overall, the study demonstrates the effectiveness of integrated biomonitoring approaches for detecting ecological zonation and water quality in river ecosystems.