Interactive effects of warming, nutrient enrichment, and substrate type on zooplankton communities associated with submerged macrophyte

Abstract Warming and eutrophication can alter the structure of aquatic communities. In shallow lakes, zooplankton associated with submerged macrophytes exhibit high species richness and play a key role in maintaining clear-water conditions and enhancing water quality. However, their responses to warming and eutrophication remain poorly understood. We conducted a 65-day mesocosm experiment to evaluate the effects of temperature (ambient vs . warmed), nutrient concentration (oligotrophic vs . eutrophic), and substrate type (natural vs . artificial macrophytes) on the richness, density, biomass, and mean body size of the zooplankton community associated with Egeria densa . Temperature negatively affected density but positively affected mean community body size, likely reflecting shifts in species dominance under warming, despite reductions in body size at the individual species level. In natural macrophytes, temperature influenced species richness under eutrophic conditions, whereas in artificial macrophytes, temperature effects on richness were observed under oligotrophic conditions. These results demonstrate that warming and eutrophication can strongly modify the structure of the zooplankton communities associated with macrophytes. Such sensitivity suggests that, under ongoing climate change, the capacity of these communities to contribute to the maintenance of clear water may be substantially reduced.