Downstream impact of Mogi-Guaçu River damming on the benthic invertebrates (São Paulo State, Brazil)

BRANDIMARTE¹, A.L., ANAYA², M. & SHIMIZU¹, G.Y.

¹ Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo – Rua do Matão, Travessa 14, 321. CEP 05508-900 - Cidade Universitária, São Paulo/SP. anabrand@ib.usp.br and yuka@ib.usp.br

² Universidade Cidade de São Paulo - Rua Cesário Galeno, 432/483. CEP 03071-000- Tatuapé, São Paulo/SP. manaya@mandic.com.br

ABSTRACT: Effects of damming the Mogi-Guaçu River (São Paulo State, Brazil) on the downstream invertebrate community were examined. Samplings were conducted at a site downstream of the dam prior to, during and after reservoir filling. In the pre and postfilling phases, taxa richness tended to increase during periods of low surface current velocity. This fact could be associated with higher organic matter availability and/or a lower remotion of organisms. Density and richness values remained in the range observed before damming whereas taxa composition changed after filling. However, the impact over taxa composition was not severe because extreme changes of similarity were not observed between pre and post-filling periods.

Key-words: benthic invertebrates; reservoir filling; post-filling phase, downstream impact.