The study of Ephemeroptera, Plecoptera and Trichoptera associated with litter in southeastern Brazil streams aimed to answer the following questions: 1) Does richness and composition of EPT fauna differ between riffle and pool mesohabitats despite being associated to the same substratum, litter? 2) Does the similarity of the EPT fauna between both mesohabitats change with time? 3) Does the EPT functional feeding structure differ between both mesohabitats (riffles-pools)? In order to answer these questions, monthly collections, from November 1999 to June 2000, were done in Ribeirão (Stream) Bocaina with a D-net (10 litter patches in riffles and 10 in pools). The EPT fauna at Ribeirão Bocaina was more diversified and more abundant in the litter in riffles than in the litter in pools, although, when richness was standardized for the same number of individuals it became similar in both conditions. EPT fauna was very different between both mesohabitats in terms of faunal composition as well as in terms of function. Probably it was due to differences in water speed, in the time of litter residence and in the concentration of dissolved oxygen between both mesohabitats.
Aquatic insects; aquatic macroinvertebrates; EPT; lotic environments
