Abstract
This research concerns the patterns of variations in the zooplankton community density in Batata Lake,
State of Pará, Brazil. Four collections were made during one year at distinct phases of the regional
hydrological cycle. Together with the zooplankton community density, the water temperature, transparency,
pH, concentration of suspended solids, chlorophyll-a and dissolved oxygen were determined. The chief
objectives of the work were the observation of the spatial and temporal variations of the zooplankton
community density and their relationships to the ambient variables measured; and the identification of the
possible influence on these organisms of the fine particulate clays, tailings from bauxite processing, that
have been discarded into the lake for ten years. The temporal fluctuations and the reduction in plankton
density observed in the affected area of the lake are discussed, considering factors such as water level
fluctuation and changes in the quantity of suspended inorganic matter and the direct consequences for the
zooplankton, as well as effects through interactive mechanisms with other ambient variables such as
phytoplankton primary production.