Structure of aquatic macroinvertebrate communities in streams of a sub-basin in the Pampa Biome, Southern Brazil

Abstract

The Piratinim River is located in the northwest of Rio Grande do Sul, and represents an important effluent from the Uruguay River, with streams located far from urbanized areas, in conditions similar to those of environmental integrity, but under the influence of agricultural activities. In this study, we aim at investigating the structure of the aquatic macroinvertebrate community in streams of the Piratinim river basin by observing both spatial and local scales. The sampling was carried out in six streams distributed in three regions (upper, middle and lower) of the basin, thus exploring its upstream, intermediate and downstream stretches, during spring and autumn. Macroinvertebrates were collected using aquatic dipnets and were identified at the family level; trophic-functional categories were established according to the classification adapted to the state of Paraná. The spatial and temporal variations of the groups and of the biotic attributes (density, richness, diversity and equitability) were subjected to Kruskal-Wallis non-parametric tests and a posteriori Dunn’s tests. The abiotic variables were obtained to verify possible influence on the composition of the macroinvertebrate community, evaluated through a Canonical Correspondence Analysis. We sampled 11,564 macroinvertebrate individuals from 72 taxa, and found a predominance of the collector-filter trophic group. Abundance and richness were different between streams; the highest densities were found in the streams located in the upper region of the watershed (Chuní and Itú). The highest taxon richness was found in the lower region of the watershed (Guaracapa stream), and the lowest richness was found in the two streams for the intermediate region (Santana and Ximbocu). Diversity and equitability did not vary; temporal variations were not found. Canonical correspondence analysis explained 31.7% of the data variability. The main environmental variables that influenced macroinvertebrates distribution were temperature, electrical conductivity, dissolved oxygen, altitude and extension of the riparian forest. Seasonality and the longitudinal gradient along the basin represented determining factors for the structure and distribution of the macroinvertebrate community in the tributary streams of the Piratinim River.

Assessing the taxonomic sufficiency of macroinvertebrate communities and their potential to distinguish the impacts of land use on lowland streams in Uruguay

“…In this study, the use of a taxonomic resolution at the family level or even coarser (order level) proved to be useful and sufficient in significantly distinguishing between different land uses, consistent with previous studies (Ruellet & Dauvin, 2007;Springer, 2010;Hentges et al, 2021). It is worth noting that for our study sites, some orders (i.e., Amphipoda, Littorinimorpha, and Rhynchobdellida) typically had only one family present, which increases the efficiency of work at the order level.…”

Spatio-temporal distribution of preimaginal black flies (Diptera: Simuliidae) in streams of a sub-basin of the Uruguay river basin, southern Brazil

“…These results, obtained in Comandaí river sub-basin, may be related to the greater environmental homogeneity caused by anthropogenic actions. Hentges et al (2021) state that in the Piratinim river basin, environmental conditions close to biological integrity predominate.…”

Potencial Uso De Los Macroinvertebrados Como Indicadores De La Calidad Del Agua en Cuencas Altas De Bajo Impacto: Caso De La Cuenca Del Arroyo San Francisco, Uruguay

“…Structural variables, such as taxonomic density and richness, and the proportion of different indicator taxa, such as the percentage of Ephemeroptera, Plecoptera, Trichoptera (EPT), or the percentage of Oligochaeta individuals, are usually strong predictors of water quality (Miserendino, 2009;Hussain, 2012). If no major land use alterations occur, the taxonomic richness of macroinvertebrates is expected to be high in mid-order streams and in intermediate positions along a river network (Miserendino, 2009;Doretto, Piano y Larson, 2020), often being influenced by stream width (Chaves, Chainho, Costa, Prat y Costa, 2005), and the width of the riparian forest (Hentges et al, 2021). However, a decrease of macroinvertebrate richness and density in streams is generally a consequence of intensification in land use or spatially localized impacts (Chavez et al, 2005;Miserendino, 2009;Hentges et al, 2021;Sargac et al, 2021).…”

“…If no major land use alterations occur, the taxonomic richness of macroinvertebrates is expected to be high in mid-order streams and in intermediate positions along a river network (Miserendino, 2009;Doretto, Piano y Larson, 2020), often being influenced by stream width (Chaves, Chainho, Costa, Prat y Costa, 2005), and the width of the riparian forest (Hentges et al, 2021). However, a decrease of macroinvertebrate richness and density in streams is generally a consequence of intensification in land use or spatially localized impacts (Chavez et al, 2005;Miserendino, 2009;Hentges et al, 2021;Sargac et al, 2021). Species richness of the EPT group sometimes decreases from upstream to mouth of the riverine system, responding to changes in land use in the basins (Miserendino and Pizzolon, 2003).…”