Spatio-temporal variation of hydrobiological communities (Animalia: Invertebrata) downstream of the El Quimbo dam, Huila, Colombia

Objective: To analyze preliminarily the hydrobiological communities of macroinvertebrates downstream of the El Quimbo dam, Huila, Colombia, to establish possible changes from the dam construction date to the second year of commissioning, in a period of seven years of samplings (2011-2017). Scope: To establish possible changes in space-time based on the analysis of diversity parameters and the BMWP and ASPT index. Methodology: Aquaticinvertebrates were collected during seven years at six sampling stations using Surber traps in 10 sites along 100 m; the specimens were preserved in ethanol 70%. The diversity parameters (abundance, richness of species, density and Hill numbers) and the BMWP and ASTP indexes were analyzed throughout the sampling period to relate them to some environmental factors. Main results: 36,490 specimens that belong to 11 classes, 26 orders, 79 families and 168 taxa were analyzed. Decreases in the BMWP/Col and ASTP indices were observed in the MGE1, MGE2 and MGE3 sampling stations, during the first phases of the project. Abundance increased significantly in mid 2013, during the river diversion stage, as well as during the operation years, while richness of species and potential richness of species increased at the beginning of 2012, 2015 and 2017, possibly synchronizing with the start of the rainy season. Conclusions: Reductions in the biodiversity indices and parameters were observed in the MGE1, MGE2 and MGE3 stations, in the river diversion and filling phases, which normalized towards the second year of operation of the dam.