Phytophilous chironomidae (Diptera) and other macroinvertebrates in the ox-bow Infernão Lake (Jatai Ecological Station, Luiz Antonio, SP, Brazil).

Abstract

Infernão Lake, located within the Jataí Ecological Station in Luiz Ant nio Municipal district (São Paulo State, Brazil), is one of the most typical ox-bow lake of the Mogi-Guaçu River, and it presents, as the main feature, its great quantity of aquatic macrophytes, whose intensive development, in the last years practically covered the whole mirror of water. With the purpose to point out the composition and to establish the relative participation of the phytophilic zoocoenosis that inhabits the different macrophytes of that lake, a collection program of the main vegetation stands was established. The collections, were carried out randomly, during dry season (1994), in stands of Salvinia auriculata, Utricularia sp., Cabomba piauhyensis, Eichhornia azurea and Scirpus cubensis being used specific methodology for each vegetable type. The analysis of the different macrophytes showed the presence of 4,130 macroinvertebrates of 28 families, in which Chironomidae (Diptera) and Naididae (Oligochaeta) were the most representative, contributing on the average with 51% and 25% of the total fauna. Asheum, Beardius, Chironomus, Goeldichironomus, Parachironomus and Polypedilum were the most abundant Chironomidae genera. Species of the genus Dero (Dero) and D. (Aulophorus) represented the most typical Naididac of the phytofauna. With clear faunistic gradient from the shore to the center of the lake, the taxocoenosis indicated low similarity (PSc < 50%), evidencing its own characteristics of each biotope. On the contrary, there was a high similarity (PSc > 60%) among the associated communities on different vegetables, when grouped into feeding guilds, with expressive participation, in most of the macrophytes, of the collector-gatherers category, except on S. auriculata, whose predators (> 50%) and collector-filterers (> 20%) dominance turned that zoocoenosis distinct from the others.