1 Grupo Ecologia de Rios do Semiárido,

Benthic invertebrates and the habitat structure in an intermittent river of the semi-arid region of Brazil Macroinvertebrados bentônicos e a estrutura do habitat em um rio intermitente do semiárido brasileiro Interactions between the habitat structure and physical and chemical parameters generate environmental conditions that influence the distribution and abundance of macroinverte-brate species and their assemblages. This study describes the habitat structure and its ef-fects on macroinvertebrate composition in an intermittent stream in the Brazilian semi-arid. Collections of benthic invertebrates were performed in three reaches along the Ipanema River during the dry and wet seasons using a “D ” shaped net (40 cm wide and 250 μm mesh). A total of 23 taxa was recorded, Insecta being the most representative with 12 fami-lies and an average density of 168.1 ind/m. Correlations between environmental variables and CCA axes showed that substrate composition (sand and mud), macrophytes, litter and altitude were the main variables explaining benthic macroinvertebrate composition in th