Linking environmental uniqueness, local physicochemical variables, and human disturbance to zooplankton functional uniqueness in tropical ponds and streams

Abstract Human activities are reshaping tropical freshwater ecosystems into heterogeneous land-use mosaics, profoundly altering environmental conditions, species distributions, and ecosystem functioning. We assessed how environmental uniqueness, physicochemical conditions, land use, and spatial structure drive zooplankton functional uniqueness (local contribution to beta diversity) in Amazonian ponds and streams. Across 68 sites in Pará, Brazil, we identified 149 zooplankton taxa classified into eight functional traits. In streams, abundance-based functional uniqueness increased with environmental uniqueness but decreased with dissolved oxygen and spatial structure, whereas presence/absence-based uniqueness was positively associated with mining intensity. In ponds, landscapes dominated by forest and pasture showed reduced abundance-based uniqueness, whereas presence/absence-based uniqueness increased with temperature. These patterns reveal that distinct local and landscape factors shape zooplankton functional uniqueness depending on ecosystem type (pond or stream) and diversity metric. By integrating trait-based and landscape perspectives, our findings show that zooplankton functional uniqueness is not inherently linked to habitat conservation status and does not respond uniformly to environmental gradients, emphasizing the need for ecosystem-specific and metric-sensitive approaches to biodiversity conservation in heterogeneous tropical landscapes under escalating anthropogenic pressures.