Areas with minimal anthropogenic influences are frequently used as reference sites and represent the best ecological state available in a region. Streams in such conditions are necessary for evaluating the conservation status of aquatic ecosystems of a region and to monitor them, taking natural environmental variability into consideration. Therefore, the aim of the present study was to analyse whether hydrological units are reliable regional units for aggregating reference sites. To this end, reference sites were studied in three different landscape units of the same hydrological unit. The study tested the hypothesis that water quality, physical habitat structure and the composition and structure of macroinvertebrate assemblages will be more similar for sites in the same landscape unit than for sites located in different landscape units in the same hydrological unit. The study showed that taxonomic richness and composition of the macroinvertebrate assemblages were negatively affected by site slope and positively affected by the presence of leaf packs on the streambed. The three landscape units supported significantly different macroinvertebrate assemblages and indicator taxa. Therefore, a hydrological unit does not constitute a homogeneous entity in terms of environmental variables and biological composition if it incorporates high landscape heterogeneity. These results should improve and facilitate the selection of reference sites for biomonitoring programs and for managing tropical headwater streams.

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Reservoirs are artificial ecosystems with multiple functions having direct and indirect benefits to humans; however, they also cause ecological changes and influence the composition and structure of aquatic biota. Our objectives were to: (1) assess the environmental condition of Nova Ponte Reservoir, Minas Gerais state, southeastern Brazil; and (2) determine how the aquatic biota respond to disturbances. A total of 40 sites in the littoral zone of the reservoir were sampled to characterize physical and chemical habitat, land use, and benthic macroinvertebrate and fish assemblages. The predominant type of land cover near the reservoir was natural vegetation. A total of 29 fish species and 39 macroinvertebrate taxa were collected, including eight alien species. Most sites had intermediate levels of human disturbance, however, high levels of degradation were associated with high proportions of alien species. Disturbances at multiple scales may alter natural patterns and processes, leading to environmental changes and damaging biological communities. Our results reinforce the importance of assessing reservoir ecological conditions at several scales. The study of land use, littoral zone physical habitat characteristics, water quality, and assemblage structure set the ground for proposing actions to rehabilitate and conserve aquatic ecosystems. Keywords: reservoirs, water quality, bioindicators, physical habitat, environmental quality.MARTINS, I., SANCHES, B., KAUFMANN, P.R., HUGHES, R.M., SANTOS, G.B., MOLOZZI, J., CALLISTO, M. Avaliação Ecológica de um reservatório no sudeste do Brasil.http://dx.doi.org/10.1590/1676-06032015006114Resumo: Reservató rios sã o ecossistemas artificiais com mú ltiplas funçõ es e que oferecem benefícios diretos e indiretos ao homem; no entanto, também causam mudanças ecoló gicas e influenciam a composiçã o e estrutura da biota aquá tica. Os objetivos deste estudo foram: (1) avaliar a condição ambiental do reservató rio de Nova Ponte, Estado de Minas Gerais, sudeste do Brasil; e (2) verificar se a biota aquá tica responde aos distú rbios. No total, 40 sítios amostrais na regiã o litorâ nea do reservató rio foram amostrados para caracterizar os habitats físicos e químicos, cobertura e uso do solo, assembleias de macroinvertebrados e peixes. Vegetaçã o natural de cerrado foi o tipo predominante de cobertura do solo no entorno do reservató rio. 29 espécies de peixes e 39 taxa de macroinvertebrados bentô nicos foram coletadas, incluindo oito espécies exó ticas. A maioria dos sítios amostrais possui níveis intermediá rios de distú rbio antró pico, porém o aumento de alteraçõ es antró picas foi associado ao aumento do nú mero e abundâ ncia de espécies exó ticas. Distú rbios em mú ltiplas escalas podem alterar os padrõ es e processos naturais, levando a mudanças ambientais e nas comunidades bioló gicas. Nossos resultados reforçam a importâ ncia de avaliar as condiçõ es ecoló gicas do reservató rio em vá rias escalas. O estudo do uso e cobertura do solo, características de habitats físic...

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This book is dedicated to the memory of our friend Volney Vono. We miss him, his funny stories, and his ecological knowledges.

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