Dinâmica de macroinvertebrados em duas classes de àreas úmidas (formação palustre e meandro antigo de rio) de uma planície de inundação da bacia do Rio dos Sinos

Abstract

The objective of this study was to evaluate the effects of floods and drought on the macroinvertebrate richness, density and composition in two wetland classes (palustrine wetland and oxbow lake) associated to a floodplain system of the Sinos River basin over an annual cycle (2003-2004). The studied area was located in Novo Hamburgo city (Lomba Grande), in the South of the Brazil (Rio Grande do Sul). In each wetland class, twelve collections were carried out during an annual cycle (Apr 16/2003 to Mar 12/2004). In each collection, five samples were collected at random along an transect. The collections were developed using a corer (75 mm diameter) inserted 5 cm into the substratum. A total of 1,229 macroinvertebrates representing 50 taxa was observed in the oxbow lake and 1,930 macroinvertebrates distributed in 48 taxa were collected in the palustrine wetland. The majority of the taxa corresponded to aquatic insects (67.3% in the oxbow lake and 69.4% in the palustrine wetland). The macroinvertebrate richness (