were the dominant species. While no significant short-term variation was observed in hydrological or biological parameters, fluctuations related to tidal height were recorded in abiotic parameters and the density of the principal zooplankton taxa. The temporal variation in copepod populations tended to reflect that of total zooplankton abundance. Mean zooplankton density varied from 509.1 ind.m-3 (ebb tide, at 16:30 h) to 25,514.3 ind.m-3 (flood tide, at 10:30 h), with an overall mean of 5,872.1±8,286.4 ind.m-3. Oscillations in the density of P. quasimodo, L. fluviatilis, and P. marshi were influenced by the morphological and morphodynamic characteristics of the Taperaçu estuary, associated with the recruitment of individuals from the adjacent Caeté estuary, which constitutes an important factor determining the structure of the zooplankton community recorded in the present study.