Litter production and aquatic macroinvertebrates on a headwater subtropical stream in Rio Grande do Sul State, Brazil - DOI: 10.4025/actascibiolsci.v31i3.355

Abstract

The aim of the study was to verify the temporal variation of allochthonous material input into a stream, and which structures contribute to the organic material pool, as well as to analyze the occurrence of macroinvertebrates associated with the litter. Samples were taken from October, 2004 to October, 2005 in two transects along the riparian zone. At each transect, three sampling stations were chosen. At each one, submersed and suspended collectors (1.5 m above bottom) were installed. Input and retention of coarse benthic organic material were analyzed and classified as flowers and diaspores, (seeds and fruits) and vegetative structures (leaves and branches). There were no statistical differences between input of material in suspended and submersed collectors. Therefore, no statistical differences were verified for exposure time for both the suspended and submersed collectors. Vegetative and seeds and fruits and flowers structures differed in relation to their vegetal composition input for total exposure times for both collectors. Leaves were the most important structure for biomass. Aquatics insects, crustaceans, mussels and worms were the most common macroinvertebrates associated with litter. Insecta-Diptera, mainly Chironomidae – and Oligochaeta were the most abundant taxa associated with the submerged and suspended collectors. The major taxa richness was found in submerged collectors.