Macrophytes' presence alters zooplankton composition and abiotic conditions in a reservoir in Northeastern Brazil

Plankton Dam Diversity Aquatic ecosystems

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May 13, 2026

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Our objective was to analyze the composition of zooplankton in areas with and without macrophytes in the Rio Preto do Criciúma Reservoir, Jequié-BA, and to associate it with different water conditions (physical and chemical parameters) and changes in zooplankton species composition. The physical-chemical parameters of water (water temperature, pH, electrical conductivity, redox potential, turbidity, dissolved oxygen and dissolved solids, water transparency, chlorophyll-a, and suspended material) and the zooplankton community were sampled at four points in a single campaign in June 2022 at the Rio Preto do Criciúma Reservoir, in the municipality of Jequié, Bahia, Brazil. Two samples were collected in the central region (without macrophytes), and one sample was collected on each of the left and right margins of the reservoir (with macrophyte banks). We observed that the presence of macrophytes on reservoir margins was associated with distinct water parameters and altered zooplankton composition. We observed five species exclusive to the limnetic region (without macrophytes) and seven exclusives to the littoral region (with macrophytes). Chlorophyll-a and temperature were associated with the presence of macrophytes, while dissolved oxygen, electrical conductivity, pH, and redox potential were associated with the absence of macrophytes. The Rio Preto do Criciúma Reservoir is suffering from uncontrolled anthropic activities on its margins, activities that have the potential to alter water conditions, species establishment, and biological interactions. Therefore, our study contributes to a better understanding of the relationships among macrophytes, water conditions, and zooplankton composition in reservoirs before these activities worsen and alter these relationships.