Spacial distribution of aquatic insects (Ephemeroptera, Plecoptera and Trichoptera) in cerrado streams of the Parque Ecológico de Goiânia, Goiás State

Abstract

The aim of this research was to make a faunistic survey of the immature forms of benthic insects of the orders Ephemeroptera, Plecoptera and Trichoptera at the Parque Ecológico de Goiânia, Goiás State. An area of 1 m² was sampled in 14 sites in the dry (Seplember/1994) and rainy (January/1995) seasons. Some abiotic factors -- temperature, velocity, flow, conductivity, oxy-reduction and pH were recorded in some sites. The faunistic cornposition in the dry period was 73% Ephemeroptera, 1% Plecoptera and 26% Trichoptera, and in the rainy period 57%, 1% and 42%, respectively. A reduction in the density of immature forms in rainy period was noted, when only 2.129 specimens were collected, while the number for the dry period was 16.220. The data were analyzed by cluster techniques (UPGMA). They showed a distinct spatial pattern in the dry season, but a less clear one in the rainy season.