Benthic macroinvertebrate dynamics in a shallow floodplain lake in the South of Brazil
MALTCHIK, L.1; FLORES, M.L.T. & STENERT, C.
1 Laboratório de Ecologia e Conservação de Ecossistemas Aquáticos, Universidade do Vale do Rio dos Sinos, 93022-000, São Leopoldo, RS, Brasil; e-mail: maltchik@unisinos.br
ABSTRACT: The objective of this study was to analyze the effects of the floods on the macroinvertebrate richness, density and composition in a shallow lake associated to a floodplain system over one year (from May 2001 to April 2002) in the South of Brazil. A total of 1.292 macroinvertebrates representing 25 morphotypes distributed in 20 families and one class (Oligochaeta) was obtained. The majority of the morphotypes was aquatic insects (76.2%). From the total of the organisms found, 53.6% belonged to Leptoceridae, which dominated over the period with floods, and 31.3% belonged to Oligochaeta, which dominated over the period without floods. The richness and density of macroinvertebrates varied during the studied year and they were greater in the period without floods than the period with floods. Floods of brief duration were enough to diminish the richness and density of macroinvertebrates. The macroinvertebrate richness, density and composition were not influenced by the water depth and temperature and lake area. These results showed that flood events, even of brief duration, influence the macroinvertebrate dynamics in riverfloodplain systems of the Neotropical region.
Key-words: macroinvertebrates, river-floodplain system, flood pulse, Neotropical Region.