Abstract
The aim of this work is to evaluate the ecological quality of waters along an environmentally heterogeneous basin, using macroinvertebrate biotic indices (BI). Twelve sampling sites were selected in the Río Grande basin, following an altitudinal gradient across the Puna, Monte and Yungas ecoregions. Sampling was conducted in the dry and rainy seasons, during three consecutive years (2012 to 2014). At each site, physico-chemical parameters were measured and benthic macroinvertebrates were collected. Principal component analysis (PCA) was applied to explore environmental variability in terms of physico-chemical parameters. The water quality of the basin was assessed by means of different biotic indices. Correlation analyses were performed between the biotic indices and the physicochemical parameters. Altitude, NaCl, total dissolved solids (TDS) and electrical conductivity were higher at the Puna and Monte sites, while river discharge, width and depth were higher at the Yungas sites. Biotic indices suggested good water quality. The BMWP (Biomonitoring Working Party) and family richness were the most suitable indices to simultaneously compare the rivers of the different ecoregions. The change in the composition of macroinvertebrate assemblages was observed at an altitude of 1500 m a. s. l., separating arid and humid zones and coinciding with inflection points of conductivity, NaCl and TDS.
Highlights
Aquatic insects and other benthic invertebrates are the most widely used organisms in freshwater biomonitoring (Bonada et al 2006) due to their high ubiquity and species richness, high susceptibility to disturbance and limited mobility, and because they require little sampling effort (Resh 2008)
Despite the importance of this basin, the most populated of the province of Jujuy, its macroinvertebrate diversity has been little studied, and ecological quality assessments are limited to one survey carried out using biotic indices (BI) based on aquatic organisms from a short section around the foothills (Fernández et al 2006)
The Puna ecoregion is located above 3000 m a. s. l., its relief is more or less flat crossed by some mountain ranges
Summary
The Río Grande basin in the province of Jujuy has an extension of ~240 km, an average width of 50 km and drains a region of 7250 km, with channels totaling about 1900 km. In the six sites of the main channel (Río Grande), invertebrate quantitative samples were taken in rapids or streams [3 replicates using a Surber net (0.09 m2, pore 250 μm)] in dry and wet periods of 2012 and 2013 (n=72 samples). At each of these sites, qualitative samples were collected with a D net (pore 250 μm, n=24 samples), standardizing by time (15 minutes) and covering all the microhabitats present in each site (e.g., margins, pools, submerged vegetation, etc.). The invertebrates were preserved in alcohol 70% and identified at the lowest possible taxonomic level using available keys
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
