The Influence of Bauxite Tailings on the Cladoceran Populations of Lake Batata,Amazonia, Brazil

Lake Batata receive tailings from bauxite mining for ten years (1979-1989). This material, with 7-9% of solid particles, changed some ecological conditions of part of the lake. In order to study the influence of this material on the cladoceran populations, seasonal and intensive studies were made of abundance and brood size of the animals and of some environmental parameters such as transparency, suspended material, POC (<30pm), total bacteria and chlorophyll a. Reduced transparency and high suspended matter attested to the greater quantity of tailings in the water column, in the area impacted by tailings. Greater oscillations of density and brood size at stations in the impacted area appear to indicate less stable conditions in this part of the lake.