Browsing by Author "Vimos Lojano, Diego José"

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Community structure and functional feeding groups of macroinvertebrates in pristine andean streams under different vegetation cover
(2020) Vimos Lojano, Diego José; Hampel, Henrietta; Vázquez Zambrano, Raúl Fernando; Martinez Capel, Francisco
© 2020 European Regional Centre for Ecohydrology of the Polish Academy of Sciences As a function of the dominant vegetation cover, patterns of variation in the structure and composition of both, the aquatic macroinvertebrate communities and their functional feeding groups (FFG) were examined at pristine streams of two high Andean micro-catchments of southern Ecuador. Ten sampling segments were defined in the study streams surrounded by either Tussock grass (TG), Quinua forest (QF) or high mountain forest (HMF). In each segment, environmental and biological samples were collected. Different statistical analyses were implemented for assessing possible relationships between biological and environmental variables. TG and QF streams were found to share many physical and biological characteristics. HMF ecosystems, which are characterised by greater total hardness, water velocity, temperature, pH and nitrite/nitrate concentrations exhibited low values of diversity, richness, relative abundance of non-insects, piercer and parasites. Further, high values of relative abundance of Plecoptera (predators) were observed in HMF, apparently due to higher water velocities and their resistance to these flow conditions. The composition of the macroinvertebrate community showed similarity in TG and QF. It was observed at the three study sites a dominance of organisms generally tolerant to lower availability of oxygen (Chironomidae and non-insect class) and, curiously, to higher concentrations of nutrients. It was found some taxa associated with the presence of organic matter in the sediment because they use allochthonous resources (Phylloecus).
Riparian and microhabitat factors determine the structure of the EPT community in Andean headwater rivers of Ecuador
(2017) Vimos Lojano, Diego José; Martínez Capel, Francisco; Hampel, Henrietta
This research was conducted in the high‐Andean basin of the Zhurucay River in southern Ecuador. In 4 river reaches, 19 sampling campaigns were conducted per reach spread over a period of 35 months. The biotic samples were selected in the periods with greatest flow stability. Parallel to each sampling, 37 environmental variables grouped into 3 factors (riparian corridor, hydromorphology, and water quality) were recorded. The study aimed to analyse during periods of stable flow the influence of these environmental factors on the structure and density of the EPT community (Ephemeroptera, Plecoptera, Trichoptera) in a quasi‐pristine aquatic ecosystem. Multivariate statistical analysis revealed that the Froude number, gravel type, and width/depth ratio are the most relevant hydromorphological variables explaining variations in EPT density. Xiphocentronidae, Contulma, and Helicopsyche were observed to have a relationship with the order of the river, while Ochrotrichia, Nectopsyche, and Phylloicus varied with the type of riparian vegetation. Phylloicus, Ochrotrichia, and Nectopsyche were common in lentic sites, while the proportion of gravel and the width/depth ratio restricted the genus Helicopsyche. The only relevant water quality factor was the total phosphorus, which was related with 2 taxa. In conclusion, although macroinvertebrates are currently employed in water quality studies, riparian vegetation and hydromorphological factors are determinant for their communities in pristine Andean rivers. Such factors are therefore crucial in the study of environmental flows and the assessment of the ecological integrity.