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As bacias hidrográficas no Brasil têm sido fortemente degradadas pelo crescimento desordenado das cidades, que somadas ao crescimento populacional potencializam os impactos existentes nesses ambientes. Desse modo, considerando os impactos ambientais causados pela urbanização e atividades agropecuárias sobre os recursos hídricos, este estudo teve por objetivo avaliar a qualidade ambiental de corpos hídricos da Bacia do rio Pirapó, em dois períodos hidrológicos distintos. Foram coletadas amostras de água em 14 pontos ao longo do rio Pirapó e seus principais tributários, localizados no estado do Paraná, Brasil. Os resultados dos parâmetros analisados apresentaram valores dentro da legislação para recursos hídricos, nas diferentes classes analisadas. Em relação ao índice de qualidade de água (IQA), os resultados mostram que a maioria dos pontos, em ambos os períodos, estão dentro da faixa de qualidade considerada razoável ou boa. Para o Índice de Estado Trófico (IET), devido aos valores pouco variáveis, todos os ambientes analisados foram classificados como mesotróficos. Portanto, os resultados obtidos nesse estudo apontam que a qualidade da água do rio Pirapó, bem como de seus tributários, pode ser, de modo geral, considerada regular. Assim, torna-se essencial um incremento no número de estudos de monitoramento em relação ao impacto em rios, riachos e córregos urbanos dessa bacia, uma vez que esse importante corpo de água abastece inúmeros municípios da região Norte do Estado do Paraná.

Many plants may accumulate rainwater, forming phytotelmata, aquatic microhabitats inhabited by various organisms. The aim of this study was to conduct an inventory of heterotrophic flagellates associated with phytotelmata of the bromeliad Aechmea distichantha Lem., found in rocky cliffs on the Upper Paraná River. The bromeliads were removed manually from the rocky wall, the water was removed and cultures of organisms of each plant were mounted in Petri dishes. Sixteen species of heterotrophic flagellate were recorded, drawn and described, among them one species belonging to the Amorpha Domain and 15 species to the Diaphoretiches Domain. The groups with most species were Euglenida and Kinetoplastea. The low diversity of heterotrophic flagellates recorded in this study, compared to the plankton of lakes and reservoirs, is probably related to the fact that phytotelmata are habitats with extreme environmental conditions, thus selecting organisms tolerant to these environments.

Most changes in water bodies are result of human activities that have the potential to undermine the environmental integrity of aquatic ecosystems. Changes in genetic material can be evidenced by the frequency of nuclear abnormalities in fish blood cells, in response to genotoxic agents even at low concentrations. Thus, we aimed at comparing the frequencies of nuclear abnormalities of fish kept in acclimation, with fish collected in Timbó river (Santa Cruz do Timbó, Santa Catarina State), under low anthropogenic interference, and fish collected in Iguaçu river (União da Vitória, Paraná State), a polluted river. The highest frequency of changes in nuclear morphology of fish erythrocytes was found in the urbanized area around the Iguaçu river, while, the fish collected in areas with preserved riparian forest surrounding the Timbó river and acclimated fish showed no morphological changes. Our results suggest that genotoxic compounds in the Iguaçu river are acting as stressors to aquatic communities, especially fish. In addition, the absence of nuclear abnormalities in fish from the Timbó river suggests that rivers without significant environmental changes can serve as reference point for comparative studies of genetic modifications for the species studied.

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