Environmental filtering links zooplankton community assembly and resource-use efficiency in the River Danube

Here, we examined how local environmental conditions and biodiversity jointly shape resource use efficiency (RUE) of zooplankton communities in the middle section of the Danube River (Hungary). We combined four years (2021–2024) of weekly field data on zooplankton abundance, functional traits, and phytoplankton biomass to quantify zooplankton resource use based on both taxonomic and functional diversity measures.

Among environmental variables, water temperature and discharge were the strongest predictors of zooplankton community structure. Zooplankton richness and evenness were positively associated with RUE, suggesting that both community composition and dominance patterns drive resource use efficiency in the Danube plankton. When considering all diversity measures jointly, functional richness remained a systematically positive predictor of RUE, coupled with a positive effect of high dominance by Rotifera during seasonal windows.