The impact of climate warming on biomanipulation effectiveness in mitigating eutrophication in shallow small water ecosystems

• Biomanipulation continues to effectively mitigate eutrophication under climate warming. • Lake ecosystem model includes zooplankton groups: rotifer, cladoceran, and copepod. • Macrophyte re-establishment is nearly twice as effective as fish removal in mitigation. • Rising temperature inhibit zooplankton, accelerating eutrophication. • Theoretical basis of biomanipulation aids lake management and restoration under climate warming. Climate change and eutrophication jointly accelerate food web simplification. They also lead to water quality deterioration, especially in shallow small water ecosystems (SWE). Manipulating fish and macrophytes to control food webs is a feasible way to mitigate eutrophication effects. However, climate warming may significantly alter the efficacy of such biomanipulation, potentially undermining or reversing management outcomes, so clarifying their interaction is critical for lake management. Existing studies have not systematically explored how climate warming might stimulate biomanipulation’s ability to mitigate eutrophication under a scientific hypothesis framework. Thus, this study utilizes a calibrated one-dimensional lake ecosystem model, the Water Ecosystems Tool (WET), which includes three freshwater zooplankton groups, rotifers, cladocerans, and copepods to represent a SWE, the Sutla River oxbow lake in Croatia. Using IPCC future climate projections, we ran a set of warming scenarios to analyze how climate warming affects zooplankton dynamics and biomanipulation success, and to determine which of the two biomanipulation methods better mitigates eutrophication. The modeled results showed that when the temperature was increased by 1°C, 1.8°C, 2.3°C, and 3.7°C, reducing the fish biomass by 50 % would result in a 8 %, 20 %, 23 % and 23 % decrease in Chl a , respectively, while increasing the macrophyte coverage by 50 % would result in a 24 %, 41 %, 42 % and 48 % decrease in Chl a , respectively. Generally, due to the advantage in trophic transfer efficiency of the food webs, macrophyte re-establishment is nearly twice as effective compared to fish removal under climate warming conditions. However, the effectiveness of macrophyte re-establishment compared to fish removal decreases as the temperature rises due to the indirect inhibitory effect of rising temperatures on zooplankton community dynamics via the food webs. Our study quantitatively predicts the trophic cascade effect of biomanipulation under four temperature-increase climate scenarios, supports macrophyte re-establishment as a viable eutrophication mitigation method for lakes under warming, guides protection strategies amid global climate change, and inspires follow-up research on related mechanisms.