Environmental factors related to anuran assemblage composition, richness and distribution at four large rivers under varied impact levels in southeastern Brazil
2011
De Souza, A. M. | Eterovick, P. C.
The margins of large rivers are usually impacted by human settlements and activities, which may affect the occupancy and use of riparian habitats by many organisms. Among vertebrates, amphibians are likely the most sensitive to environmental changes, and they can be used as a model to identify attributes of the riparian habitats that are important for the maintenance of high species richness and functional diversity. We studied anuran assemblages in four large rivers of the Velhas River basin in southeastern Brazil during one year, focusing on features of the rivers and riparian habitats that influence species distribution. We tested whether a river under greater anthropogenic impact would shelter less species compared to three rivers of equivalent size under lower impact level, and whether lower species richness related to lower availability of preferred microhabitats. We found soil type at river margin and riparian vegetation structure to be the main factors influencing anuran distribution. Species richness was positively related to microhabitat diversity and availability of preferred microhabitats, which were the lowest in the most impacted river. Most species recorded at the rivers were not breeding there, and were present in larger numbers during the dry season, when temporary bodies of water dry at the vicinities of the large rivers. Conservation of a broad extension of the riparian habitat (200 m or more) would be efficient both to provide appropriate microhabitats for anurans and to maintain connectivity between breeding sites and large, permanent rivers used by several species during the dry season.
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