The water of high Andean lakes is strongly affected by anthropic activities. However, due to its complexity this ecosystem is poorly researched. This study analyzes water quality using Sentinel-2 (S2) images in high Andean lakes with apparent different eutrophication states. Spatial and temporal patterns are assessed for biophysical water variables from automatic products as obtained from versions of C2RCC (Case 2 Regional Coast Color) processor (i.e., C2RCC, C2X, and C2X-COMPLEX) to observe water characteristics and eutrophication states in detail. These results were validated using in situ water sampling. C2X-COMPLEX appeared to be an appropriate option to study bodies of water with a complex dynamic of water composition. C2RCC was adequate for lakes with high transparency, typical for lakes of highlands with excellent water quality. The Yambo lake, with chlorophyll-a concentration (CHL) values of 79.6 ± 5 mg/m³, was in the eutrophic to hyper-eutrophic state. The Colta lake, with variable values of CHL, was between the oligotrophic to mesotrophic state, and the Atillo lakes, with values of 0.16 ± 0.1 mg/m³, were oligotrophic and even ultra-oligotrophic, which remained stable in the last few years. Automatic S2 water products give information about water quality, which in turn makes it possible to analyze its causes.

This study assessed the water quality and ecological integrity of the Columbe River micro-watershed in the Ecuadorian Andes through a multidimensional approach incorporating biotic, physicochemical, and structural indices. Indices such as the Andean Biotic Index (ABI), Biological Monitoring Working Party index adapted for Colombian conditions (BMWP-Col), Fluvial Habitat Index (IHF), Riparian Quality Index adapted for Andean conditions (QBR-And), and Water Quality Index (WQI) characterized environmental quality gradients and evaluated the impact of human activities across 11 monitoring sites. Hierarchical cluster analysis classified sampling sites into three groups: less polluted (LP), moderately polluted (MP), and highly polluted (HP). HP sites showed elevated levels of biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), electrical conductivity (EC), and turbidity, alongside low biotic and structural scores, indicating advanced ecological degradation. Conversely, LP sites demonstrated greater ecological integrity, despite elevated BOD₅ and COD levels across the watershed, suggesting widespread diffuse contamination. The findings identify anthropogenic activities such as livestock, agriculture, and domestic discharges as major pressures on water quality and macroinvertebrate biodiversity. Significant correlations between physicochemical parameters—including BOD₅ and EC—and declining biotic indices underscore the link between chemical water degradation and ecological fragmentation. In this context, this study highlights the critical need for comprehensive management and restoration strategies to combat pollution, safeguard relatively pristine areas, and rehabilitate the ecological integrity and connectivity of high-altitude Andean aquatic ecosystems under anthropogenic pressure.

Identifying the SOC levels and revealing the potential of SOC storage of ecosystems difficult to sample and study are necessary contributions to the understanding of the global reserves of SOC. Wetlands store large amounts of SOC within their soils. They have an important role in water regulation and have great biological and floristic diversity. Therefore, this study aimed to assess the SOC stock in Atillo micro-watershed in the Ecuadorian Andean wetlands at two soil depths (0–30 cm and 30–60 cm below ground) and to assess the importance of the ecosystem and its conservation in favor of reducing emissions due to degradation processes. For that, we sampled the study zone with 101 composite samples of soil to obtain the SOC storage for each sample point in Mg/ha. A SOC estimation to evaluate its spatial distribution was performed using the geostatistical method Kriging. The results show a high storage capacity of the study zone with SOC values of 126 to 454 Mg/ha in the 0–30 cm soil profile and 148 to 350 Mg/ha in the 30–60 cm soil profile. The preservation and protection mechanisms of high SOC reserves should be taken into account to prevent the emission of CO₂.

This study evaluated the physicochemical characteristics, organic matter content, and heavy metal accumulation in the sediments of four Andean lakes in central Ecuador, considering their trophic states and protection status. A total of 96 sediment samples were collected and analyzed for electrical conductivity, pH, organic carbon, phosphorus, and heavy metal concentrations (Fe, Mn, Ni, Zn, Cu, Pb). The ecological risk was assessed using the potential ecological risk index (PERI) and pollution load index (PLI), and significant environmental predictors were identified using a classification and regression tree (CART) model. The results showed that protected lakes (Atillo and Magdalena) exhibited higher concentrations of Fe, Mn, and Ni, predominantly from natural sources, while unprotected lakes (Colta and Yambo) had greater Pb and Cu enrichment, associated with anthropogenic inputs. The PERI and PLI indices confirmed a low ecological risk across all lakes, although localized contamination was detected in Yambo and Magdalena. The CART model identified pH and phosphorus as the most significant predictors in protected lakes, whereas heavy metals and phosphate were more influential in unprotected lakes. These findings underscore the role of conservation status in shaping sediment composition and emphasize the need for targeted management strategies to mitigate anthropogenic impacts on Andean aquatic ecosystems.

Zantedeschia aethiopica L. (Lirio de agua) es una planta vascular ornamental, protectora de humedales y sistemas fluviales con alta distribución en la zona Andina del Ecuador. El objetivo de este trabajo fue evaluar el efecto tóxico del cromo VI (Cr+6) en esta planta, reconociendo sus limitaciones como bioindicadora, para lo cual se determinaron los efectos fisiológicos específicos y no específicos, entre ellos: germinación relativa de semillas (GRS), elongación radicular relativa (ERR) e índice de germinación, en unidades experimentales consistentes en concentraciones de 0, 50, 100, 200 y 300 mg/kg de Cr+6 durante 168 h. Las observaciones fueron realizadas durante 20 semanas en la etapa de germinación en plantas cultivadas en suelo contaminado en condiciones semicontroladas de temperatura, humedad y capacidad de campo. Para determinar el Factor de Bioconcentración (FBC), en poscosecha se utilizaron los índices de traslocación (IT) como concentraciones del metal en la parte aérea de la planta (tallo, hojas y flores) y en el suelo. Los resultados mostraron toxicidad similar de Cr+6 en concentraciones de 100, 200 y 300 mg/kg en la etapa de germinación y con efectos fisiológicos no específicos en el crecimiento de la planta en concentraciones de 200 y 300 mg/kg presentando ausencia de floración, enanismo y marchitamiento. Los resultados mostraron un límite CL50 de 118.96 mg/kg-de Cr+6 en el cual la planta es una especie bioacumuladora y bioindicadora de este metal.

This study evaluated the influence of soil health in riparian and ecotone zones on water quality in four high-Andean rivers (Atillo, Ozogoche, Yasepan, and Cebadas) within the Cebadas River sub-basin, Ecuador. Soil and water samples were collected from 20 sites during three field campaigns (2022–2024). Soil properties included organic carbon concentration, soil organic carbon stock (SOC), bulk density, moisture, and potential microbial activity estimated through laboratory CO₂–C efflux. Water quality parameters were integrated into the National Sanitation Foundation Water Quality Index (NSF-WQI), and riparian condition was assessed using the QBR-And index. Multivariate statistical approaches, including Random Forest and Classification and Regression Trees (CART), were used to identify the most influential predictors of ecosystem quality. Results revealed marked spatial contrasts. Riparian SOC stocks ranged from 22.8 to 32.8 Mg C/ha in the more disturbed Cebadas and Yasepan rivers to 91.4–133.6 Mg C/ha in the better-conserved Atillo and Ozogoche systems. Sites with higher SOC and lower bulk density consistently exhibited better water quality, with NSF-WQI values classified as “good”, whereas more degraded sites showed lower riparian quality and “fair” water quality. Riparian forest quality was strongly correlated with water quality (r = 0.81). Random Forest models identified ammoniacal nitrogen, fecal coliforms, and altitude as the most influential predictors of riparian ecosystem condition. These findings demonstrate that soil health and riparian integrity are tightly linked to water quality patterns in high-Andean fluvial systems and support their integration into ecosystem-based watershed management.