Aquatic entomofauna and biotic index along the Pindo Grande River, Montano Bajo Forest, in Pastaza Province, Ecuador

Maria Alexandra Endara,Demián Hinojosa-Garró

doi:10.4136/ambi-agua.2563

Abstract

Pindo Grande River water quality was analyzed during rainy seasons of 2014 and 2017 and dry seasons of 2015 and 2016. Specimens were collected using surber net, kick net and manual stone collection, from five different sites along the river. In the laboratory, specimens were identified to the lowest possible taxonomic level. Taxon richness, abundance, diversity, trophic niches, and Biological Monitoring Working Party for Colombia (BMWP/Col) index were assessed. A total of 1,695 specimens belonging to 95 taxa were collected, including 57 taxa in rainy seasons and 38 taxa in dry seasons. Class Insecta was the most abundant (98.6%). Richness was highest (3,427) at M1000 collection sites in rainy and dry seasons and varied from moderate to high (13–35) at other sites. All sampling sites had medium diversity, and organisms belonged to three trophic categories: herbivores, detritivores, and predators. Environmental water quality was medium at most sites (BMWP/Col = 102–150). All sites exhibited good conservation status (BMWP/Col = 192–152) in the rainy season; only two sites presented medium conservation status (BMWP/col = 93–67) in the dry season. Principal component analysis indicated that main variables associated with sites were NO3 and COD in upstream areas in the rainy season and O2 in the dry season. Downstream areas were grouped based on depth and width of the river in the rainy season and on pH, PO4, and conductivity in the dry season. According to analysis, the Pindo Grande River has preserved epibenthic communities; it is an oxygenated stream, but its habitats have been gradually affected by anthropogenic activities.

Highlights

Benthic macroinvertebrates represent one of the most suitable groups for the purposes of evaluating the quality of aquatic ecosystems, due to their ubiquity as a functional feeding group and the ability of some groups to withstand hypoxic conditions (López-López and Sedeño-Díaz, 2015)
NO3 and Chemical oxygen demand (COD) were associated with upstream areas in the rainy season, while O2 in the dry season
The downstream areas were grouped based on the depth and width of the river in the rainy season, and on pH, PO4, and conductivity variations in the dry season (Figure 2)

Summary

Introduction

Benthic macroinvertebrates represent one of the most suitable groups for the purposes of evaluating the quality of aquatic ecosystems, due to their ubiquity as a functional feeding group and the ability of some groups to withstand hypoxic conditions (López-López and Sedeño-Díaz, 2015). They may be powerful indicators of water quality, as they are not difficult to distinguish in the laboratory, are present throughout all seasons, frequently live for more than one year, have restricted mobility, and are integrators of ecological conditions (Plafkin et al, 1989; Khatri and Tyagi, 2015). Bojsen and Jacobsen (2003) found that the total macroinvertebrate density generally differed between wet and dry seasons

Methods

Results

Discussion

Conclusion