ECOLOGICAL ASPECTS of Cochliopidae And Lithoglyphidae ( Mollusca, Gastropoda) of ARROIO FELIZARDO, BASIN OF THE MIDDLE URUGUAY river, BRAZILIAN PAMPA (preliminary data).

Abstract

Among living organisms considered as bioindicators are the mollusks, which due to its potential of adaptation, may be found in almost all the environments, acting in a significantly way at the food web and energy flow of the aquatic ecosystems. Among the families of the gastropoda class of greater representativity of the dulciaquícola environment are the Cochliopidae and Lithoglyphidae, widely distributed in inland waters or seawater. In this context, the study aims to determine the populational density and analyse ecological aspects of the Cochliopidae and Lithoglyphidae famlies (Mollusca, Gastropoda) of the stream Felizardo, Uruguay river basin, Brazilian Pampas. Seasonal samples were collected in two seasons, spring and summer at four sampling points. So far it was possible verify that the Cochliopidae family, represented by Heleobia genus demonstrated higher density of individuals in the Felizardo stream during spring and with a reduction in summer, possibly because the stream was with a reduction in its flow. The results reveal higher adaptive potential of the family Cochliopidae in this stream compared to the Lithoglyphidae family, Potamolilthus genus, which was found lower density of individuals.