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Ecological or quality status is an integral concept that reflects the degree of deterioration of aquatic environments. To measure it, protocols have been designed that demonstrate changes in the structure and functioning of biotic communities in response to anthropogenic pressures. The ecological status of the Ánimas River was evaluated along its longitudinal axis, using the IMEERA, IMARBO, and BMWP-Col indices. The samplings were carried out in dry and rainy seasons, in four sections of the longitudinal axis. Physicochemical data of the water and hydromorphological data were taken. Macroinvertebrates were collected using a Surber net. The ions dissolved in the water were the most relevant factors of the set of physicochemical variables. The hydromorphological index indicated that the points at lower elevations in the basin presented a deficient score. Regarding the abundance and composition of macroinvertebrates, a greater abundance was reflected in the dry season and a greater richness in the rainy season. The IMEERA and BMWP-Col indices had a similar behavior with lower values in the dry season, while in the rainy phase they reached the highest records, revealing clear differences in the ecological status of the studied points. The IMARBO index presented a different behavior according to which the lowest elevation points (one and two) reflected a condition of greater deterioration compared to the highest points (three and four). In this last point, the three indices showed the best quality condition. This study contributes to the knowledge of the behavior of Andean rivers in relation to ecological quality indices. [ABSTRACT FROM AUTHOR]

Aquatic macroinvertebrates are recognized as bioindicators of water quality. In Colombia, the studies have mainly been addressed by the family taxonomic level. This work analyzes the responses in abundance, richness, and diversity of the Diptera at the genus level in high Andean rivers (Bogotá River and Fucha River), in periods of low and high waters. The specimens were collected with three methods: Surber net, hand net, and rock washing. The average temperature was 12.9 ºC and oxygen saturation was close to 100 % or more, except for the lower section of the Bogotá River, before the Villapinzón town. 13 690 Diptera were collected from ten families and 40 genera. Taxonomic richness was high with the greatest variation in the lower sections of the two streams. The Chironomidae subfamilies were the most abundant. Canonical correspondence analysis (CCA) showed that Orthocladiinae were associated with water conductivity; the Gigantodax genus (Simuliidae) did not show a clear relationship with any variable; conversely, the genus Simulium was linked to the caudal. In general terms, the association between taxa and environmental variables was clearer for genera than for families, but it was not robust enough. It is suggested that to find a higher degree of biota-environment association, it is necessary to carry out analyzes at the species level, considering local and temporal variations. [ABSTRACT FROM AUTHOR]