ABSTRACT
In this paper the spatial distribution of Plecoptera nymphs in the Almas' River basin, Pirenópolis, GO, was studied. Two Surber samples, each comprising 20 sampling units and totalling 2 m², were taken in each of the 13 stations, one during the rainy season (January 1994) and the second during the dry season (July 1994). In 5 of these stations, monthly samplings were made from June 1993 to July 1994; in these, temperature, velocity, discharge, electrical conductivity and pH were measured. Regional rainfall was also obtained. To ascertain the distribution of nymphs in the habitat, a separate sample was taken. Of the factors considered, the most important affecting the spatial distribution of the stonefly nymphs were altitude, stream order, and anthropic influence. Locally, the genera Anacroneuria and Kempnyia showed clumped distributions, but the data for Gripopteryx and Tupiperla were inconclusive due to low numbers
Subject(s)
Animals , Insecta , Brazil , Insecta , Nymph , Population Density , SeasonsABSTRACT
Tupiperla illiesi fly along the year in the coastal mountains of southeastern Brazil, with larger numbers during the warmer rainy season. In the seasonal tropical climate of Central Brazil and Serra do Cipó, MG, T. oliveirai and T. gracilis, respectively, fly along the year but the pattern is still not known. In the higher elevation (ca. 1600 m a.s.l.) of Campos do Jordão, SP, species of Tupiperla may not fly during the colder months. Seasonal size variation, a phenomenon still little understood, occurred both in tropical and subtropical climates of the states of Goiás and São Paulo