Zooplankton community density in relation to water level fluctuations and inorganic turbidity in an Amazonian lake, "Lago Batata", State of Pará, Brazil

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