Deforestation and monoculture expansion restructure zooplankton communities in neotropical reservoirs

Abstract Deforestation and monoculture expansion in tropical watersheds represent important pressures on aquatic ecosystems, yet their associations with zooplankton communities in Neotropical reservoirs remain poorly understood. We evaluated how land use and land cover are associated with the distribution, diversity, composition, and structure of zooplankton communities in six tropical reservoirs with contrasting landscape configurations and trophic conditions. Samples were collected at 12 points per reservoir during dry and rainy periods by filtering 100 L of water. A total of 112 zooplankton species were recorded, comprising 60 Rotifera, 41 Cladocera, and 11 Copepoda, with the highest species richness occurring in the oligotrophic Siriji reservoir. Zooplankton diversity varied among reservoirs, while abundance-weighted diversity showed no consistent pattern between oligotrophic and hypereutrophic conditions. Rotifers, particularly representatives of Brachionidae, showed greater numerical dominance in hypereutrophic reservoirs. A total of 28 indicator species were identified (IndVal > 70%; p < 0.05), showing associations with land use and land cover, seasonality, trophic state, and limnological conditions. Zooplankton community composition differed significantly among reservoirs (permutational multivariate analysis of variance [PERMANOVA]: F = 57.611; p = 0.001), between seasonal periods ( F = 172.245; p = 0.001), and for their interaction ( F = 65.999; p = 0.001). Partial RDA explained 54.44% of the variation in zooplankton density, with limnological variables accounting for 24.1%, land use and land cover for 17.1%, and their shared fraction for 13.1%. Overall, zooplankton community structure was strongly associated with landscape configuration and related limnological conditions, highlighting the importance of riparian vegetation conservation for maintaining aquatic biodiversity.