Invertebrados associados a pedras em córregos da Mata Atlântica

Abstract

Knowing the organization patterns of the benthic fauna in streams helps on the comprehension of the relations between habitat diversity and the invertebrates’ richness and abundance. Stones make up important microhabitats for the stream’s benthic invertebrates, usually hosting a great diversity of taxa. On this study, we tested the existence of a positive relation between the size of stones and the abundance and richness of invertebrate families, as well as if the fauna composition on smaller stones represents a subset present on bigger stones (nested pattern). We also tested if fragments within a same stream would be more similar regarding fauna composition and structure. This study was carried out in the dry season of 2014 in three different first order streams located in an Atlantic Rainforest fragment in the Southeastern region of the Minas Gerais state. In three segments of each stream, 100m away from each other, we sampled 180 stones (20 per segment) and measured environmental variables. We found a total 751 individuals distributed in 44 taxa, with a predominance of Chironomidae larvae in all streams, followes by Elmidae (stream I), Amphipoda (stream II) and Simuliidae (stream III). Low invertebrate abundance was related to low medium speed of the stream flow in the studied segemnts. Taxa composition on the stones of streams I and III showed nested organization pattern, which can be explained by the higher frequency of generalist taxa in the occupation of the habitat, represented in most of the stones. No relation was recorded between stone size and taxa abundance and richness. Taxa composition differed among streams and among adjacent segments within each stream. Such results represent important aspects that must be taken in consideration for studies on conservation and management of these ecosystems.