Abstract
AIM: the aim of this study was to determine the ecological valence of benthic macroinvertebrates at different pollution levels in highland rivers and streams of Rio Grande do Sul; METHODS: the dataset proceeds from samplings performed between 2002-2011 in 35 lotic ecosystems. The Chemical Index was used to determine pollution levels. Indices of richness and Shannon diversity were applied to characterize the structure of benthic communities. The descriptors used to determine taxa's ecological valence were selected according to Coefficient of Variation and regression analyses. Groups of tolerance were identified using Interquartile range and cluster analysis; RESULTS: Conductivity and Chemical Index were the descriptors best related with diversity of benthic macroinvertebrate community. These metrics were used to determine the tolerance range of 38 taxa. Interquartile range and cluster analysis revealed three groups of taxa, according to their occurrence in different levels of pollution: taxa with narrow amplitudes, present at sites with very low or very high load of organic enrichment; taxa with moderate amplitude, found until moderately polluted sites; and taxa with occurrence in widespread environmental conditions. The results, when compared to other studies in Brazil, showed differences in some taxa's tolerance. This observation indicates the need to assess the bioindication potential of these taxa in genus and species level; CONCLUSION: the present study contributes to increase knowledge about the bioindicator potential of benthic macroinvertebrates. Therefore, the study supports an advanced biomonitoring of ecological quality in mountain streams of southern Brazil.
Highlights
The use of biological methods in monitoring lotic ecosystems has been increasing over the last three decades, and becoming a valuable complementary tool to chemical and bacteriological analysis (Segnini, 2003)
Physicochemical measurements are routinely performed in watercourses monitoring, and these analyses are standardized and regulated (Brasil, 2005)
The survey of Rio Grande do Sul highland streams provides information on the tolerance range to the habitat physicochemical conditions of 38 benthic macroinvertebrate taxa
Summary
The use of biological methods in monitoring lotic ecosystems has been increasing over the last three decades, and becoming a valuable complementary tool to chemical and bacteriological analysis (Segnini, 2003). To lerancevaluesbasedonbenthic macroinvertebrates are one of the most widely used tools for monitoring biological impacts of water pollution, in streams and rivers (Chang et al, 2014). In Brazil, benthic macroinvertebrate communities have emerged as an important component to assess freshwater ecosystems biological integrity (Baptista, 2008; König et al, 2008; Copatti et al, 2010; Hepp et al, 2010). The development or adaptation of biological indices using these invertebrates is recent in our country (Monteiro et al, 2008; Mugnai et al, 2008; Junqueira et al, 2010; Couceiro et al, 2012). The efficient application of indices demands an expansion of knowledge about macroinvertebrate communities’ distribution patterns on different habitat conditions (Bagatini et al, 2012), in order to modify or assign tolerance values to indicator species
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