Produ o de folhi o e fauna associada de macroinvertebrados aqu芍ticos em curso d＊芍gua de cabeceira em Floresta Ombr車fila do Estado do Rio Grande do Sul, Brasil = Litter production and aquatic macroinvertebrates on a headwater subtropical stream in Rio Grande do Sul State, Brazil

作者：Cecilia Schuler Nin; Eduardo Luiz Ruppenthal; Gilberto Gonalves Rodrigues

来源：Acta Scientiarum - Biological Sciences, 2009.

• materia organica aloctone
• produ o primaria
• riachos
• macroinvertebrados aquaticos
• allocthonous organic material
• litter input
• headwater stream
• aquatic macroinvertebrates

Os objetivos deste estudo foram verificar a entrada sazonal de material al車ctone e a composi o de suas estruturas vegetais e da fauna de macroinvertebrados aqu芍ticos associados ao material al車ctone em um riacho de cabeceira em clima subtropical. Foram analisadas, trimestralmente, duas transec es longitudinais no curso d＊芍gua, onde foram instalados coletores submersos e suspensos (1,5 m acima da calha) de outubro de 2004 a outubro de 2005. Em ambos os coletores, n o se verificou diferen a para a entrada de material al車ctone entre os per赤odos de coletas, o que sugere aus那ncia definida de sazonalidade. Tamb谷m n o foram verificadas, temporalmente, diferen as para os componentes, flores, frutos e sementes (di芍sporos), folhas e galhos (vegetativas). O componente foliar foi o item com maior biomassa na forma o do material al車ctone em ambos os coletores. Larvas de insetos aqu芍ticos, crust芍ceos, moluscos e vermes oligoquetoscorrespondem aos grupos com maior representatividade. Chironomidae (Insecta, Diptera) e Oligochaeta foram os taxa mais abundantes em ambos os coletores, por谷m a maior riqueza foi observada nos coletores submersos. The aim of the study was to verify the temporal variation of allochthonous material input into a stream, and which structurescontribute 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 mostimportant structure for biomass. Aquatics insects, crustaceans, mussels and worms were the most common macroinvertebrates associated with litter. Insecta-Diptera, mainly Chironomidae 每 and Oligochaeta were the most abundant taxa associated with the submerged and suspended collectors. The major taxa richness was found in submerged collectors.