Abstract
Despite the importance of Oligochaeta to the dynamics of aquatic ecosystems and to studies of the biology of pollution, there is currently a dearth of information on this group's ecology in Brazil. The aim of this study was to describe the Oligochaeta fauna in four watercourses - three urban and one rural - in the state of São Paulo: the Pinheirinho stream, the Água Branca stream, the Monjolinho River and the Gouveia stream, respectively. Sediment samples were taken with a Van Veen grab in two areas from each watercourse, during the summer and winter of 2001. In all collection areas, measurements of the pH, electrical conductivity, dissolved oxygen and turbidity of the water were made with a Horiba U-10 device. Principal component analysis showed that axes 1 and 2 explained 68.18% of the results' variability, with the first axis predominantly associated with the granulometric data and the second one with the limnological data. Cluster analysis indicated that area II of the Monjolinho River differed from the other collection sites. In the present study, the Oligochaeta group was represented by Tubificidae, Naididae, Alluroididae, Narapidae and Enchytraeidae. Among the three species of Tubificidae, Limnodrilus hoffmeisteri Claparede, 1862, was the most abundant and most frequent species. The results provided important information on the ecology and distribution of limnic Oligochaeta.
Highlights
Despite the importance of Oligochaeta to the dynamics of aquatic ecosystems (FISHER & BEETON, 1975; LOTESTE & MARCHESE, 1994) and to studies of the biology of pollution (MILBRINK, 1983; MARCHESE & DRAGO, 1999, PRYGIEL et al, 2000; NIJBOER et al, 2004), the small number of researchers focusing on this group means there is much less knowledge on their distribution and preferred habitats than for other groups which make up the benthic macroinvertebrate communities of the Brazilian continental environments
The isolation of M2, detected in the cluster analysis (Fig. 1), indicates that this area differs from the others, because the electrical conductivity and turbidity values are considerably higher than those in the other areas studied
The results indicated the presence of four species of Tubificidae, eleven of Naididae, one of Narapidae and one of Alluroididae
Summary
O objetivo do estudo foi caracterizar a fauna de Oligochaeta em três córregos urbanos e um córrego rural, localizados na região central do Estado de São Paulo, sendo estes o córrego do Pinheirinho, Água Branca, rio Monjolinho e o córrego do Gouveia, respectivamente. Despite the importance of Oligochaeta to the dynamics of aquatic ecosystems (FISHER & BEETON, 1975; LOTESTE & MARCHESE, 1994) and to studies of the biology of pollution (MILBRINK, 1983; MARCHESE & DRAGO, 1999, PRYGIEL et al, 2000; NIJBOER et al, 2004), the small number of researchers focusing on this group means there is much less knowledge on their distribution and preferred habitats than for other groups which make up the benthic macroinvertebrate communities of the Brazilian continental environments Even though they are present in samples of benthic macroinvertebrates, Oligochaeta worms are generally referred to at the class or family level, or are omitted from any analysis of the faunistic structure and composition of lotic environments. The aim of this study was to describe the Oligochaeta fauna in four streams (three urban and one rural) in the central region of the state of São Paulo, Brazil, and to try to establish a relationship with abiotic variables that can explain the occurrence and abundance of the most representative species
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