BENTHIC COMMUNITY IN AMAZONIAN LAKE 397 INFLUENCE OF BAUXITE TAILINGS ON THE STRUCTURE OF THE BENTHIC MACROINVERTEBRATE COMMUNITY IN

This research was developed between 1993 and 1996, aiming to study the structure of the benthic macroin-vertebrate community, relating it to some abiotic variables, in an amazonian lake (lago Batata), that received for ten years a great amount of bauxite tailings. The benthic macroinvertebrates were collected with a core and the abiotic variables that were measured were: dissolved oxygen, suspended material, depth, transparency (secchi disc), temperature of the water column and total nitrogen, available phosphorus and organic matter in the sediment. With the use of a Principal Components Analysis (PCA), we were able to show that the sampling sites differed regarding the abiotic variables, especially total-N, available-P and organic matter in the sediment, all of which were found in greater concentrations in the natural areas. The PCA concerning the benthic macroinvertebrate community also distinguished the natural sites from the impacted one. The impacted site was positively grouped with the Ephemeroptera (Campsurus sp.) and the natural sites were grouped together with the Chironomidae, Chaoboridae, Oligochaeta and Bivalvia. The results achieved in this research made clear that the sites under influence of the bauxite tailings had alterations of their abiotic characteristics and of their benthic macroinvertebrate structure