Application of the biological indices Biological Monitoring Working Party and Average Score per Taxon to assess the water quality of Ouricuri river in the Municipality of Capanema, Pará State, Brazil

Abstract

Environmental problems related to water quality in continental ecosystems have conducted studies aimed at the protection and conservation of these environments. The current study aimed to evaluate the water quality in five points of Ouricuri river, located inside and outside of the urban area of the Municipality of Capanema, Pará State, Brazil, using the biological indices of Biological Monitoring Working Party and Average Score per Taxon. The result of the biological indices identified a pattern of water quality that was presented as doubtful (P1), critical (P2, P3 and P4) and very critical (P5), polluted water in moderate and severe form. The values of taxonomic richness tend to decrease downstream from point P2, with increased levels of turbidity, organic matter and total phosphorus and these last two are measured at substrate level. In the five sampled points, 1,039 individuals were identified which belong to 14 families with the main groups identified as Chironomidae, Oligochaeta and Thiaridae. The change in macroinvertebrate community composition along the Ouricuri river appears as a result of the combination of human factors associated with it, such as: loss of riparian forest, margin erosion, substrate change, domestic wastewater flows and proliferation of macrophytes.