Zooplankton Temporal, Longitudinal, and Vertical Diversity Patterns in the Floodplains of the Western Amazon

Abstract

The Western Amazon is a highly biodiverse area. Zooplankton diversity studies in the region have been primarily conducted in Peru and Colombia, with limited research in the Ecuadorian Amazon. To address this gap, our research aimed to enhance taxonomic knowledge and understand zooplankton diversity patterns in the Napo and Pastaza lower basins at different spatial and temporal scales. Two sampling expeditions were conducted in the high waters of 2021 and rising waters of 2022. Dry conditions in 2021 led to lower-than-expected water levels. The study identified 107 zooplankton species, revealing variations in richness and composition between years, lakes, and depth strata. Grande Lake, deeper and wider than Delfincocha, exhibited significant turnover variations across strata in both seasons. Despite a relative longitudinal homogenization between channels and floodplains during high waters, beta diversity across vertical and temporal gradients highlighted complex dynamic zooplankton communities in both lakes. In addition, we include the first records of 44 taxa for the Ecuadorian Amazon and 36 for Ecuador. These findings emphasize the need for targeted research and conservation efforts in the face of escalating environmental threats to the Western Amazon.