Biogeographic patterns and environmental drivers of cladocerans in surface lake sediments across China

Aquatic biodiversity is essential for maintaining lake ecosystem health, yet large-scale studies linking zooplankton communities, particularly cladocerans to environmental gradients remain limited in the world's most populous heartland (Asia). Probing cladocerans as indicators of lake ecological vitality, we surveyed 215 lakes spanning China's vast environmental mosaic. Cladocerans were found in 157 lakes, and a subset of 97 lakes with complete environmental data included in advanced statistical modeling to decode biogeographic and community-environment relationships. Water depth, electrical conductivity, and mean annual temperature emerged as dominant shapers of community structure, with southern lakes exhibit the highest alpha diversity, while lakes on the Qinghai-Tibet Plateau show the greatest beta diversity. Cladoceran community similarity exhibited statistically significant distance-decay relationships across regions. Structural equation modeling revealed climate-related variables as the overriding force on composition and diversity, further amplified by local habitat conditions and nutrient factors, exerting secondary regulatory effects. Overall, our findings enhance our understanding of how environmental gradients structure freshwater biogeography at a national scale, highlighting regionally divergent cladoceran patterns and providing a conceptual basis for biodiversity conservation and sustainable lake management. • A national-scale spatial analysis of cladoceran distributions across lakes in China and their environmental implications. • Cladoceran diversity patterns differ regionally among lakes in NC, SC, and QTP. • Cladoceran community similarity exhibited statistically significant distance–decay relationships across regions. • A multi-approach analysis elucidates the environmental drivers of cladoceran community biodiversity.