Richness and distribution of Ephemeroptera, Plecoptera and Trichoptera in Atlantic forest streams

Abstract

Knowledge about the distribution of aquatic insects in different types of mesohabitats is very important for conservation of benthic macrofauna. This study evaluated the composition and spatial distribution of the fauna of Ephemeroptera, Plecoptera and Trichoptera (EPT) in eight streams in forested areas in the southeastern region of Minas Gerais state, Brazil. The collections were carried out in the dry season, obtaining 10 litter samples from riffles and 10 from pools in each stream, using a Surber sampler. We identified 5,631 organisms of 49 EPT genera. The abundance and fauna composition values differed between the streams and mesohabitats, while the richness only differed between the streams. Eleven taxa were recorded with greatest abundance and frequency in riffles and six in pools. The results suggest that the abiotic characteristics at the stream scale (e.g., water temperature) and mesohabitat scale (water speed) are the main determinants of the variation in the structure and composition of the EPT assemblages, reinforcing the importance of separately evaluating samples from different types of mesohabitats.