# Evaluation of Algal Control Measures in Eutrophic Reservoir Based on Aquatic Ecosystem Models
###### Abstract  
The frequency of freshwater cyanobacterial blooms is increasing globally due to climate change and eutrophication, particularly in reservoirs. Reservoir ecosystems exhibit unique characteristics, and there is a complex relationship between factors such as light, temperature, nutrient salts, hydrology, and algal growth. The impact of the other factors on algal growth varies significantly among different reservoirs. Thus, it is crucial to assess the effectiveness of various algal control measures implemented in different reservoirs. This study conducted a comprehensive assessment by establishing a eutrophication model for the Shanzi Reservoir in Fuzhou City. The model incorporated meteorology, hydrology, carbon dynamics, nutrient cycling, and biological communities. The effectiveness of diverse management measures was systematically evaluated. The findings demonstrate that increasing the water level, reducing nutrient salts in sediments, and implementing ecological fish stocking effectively suppressed algal growth to varying degrees and improved nitrogen and phosphorus levels. Lower water levels and ecological fish stocking had a significant impact on algal reproduction, while sediment reduction had a minimal effect. Conversely, lower water levels and ecological fish stocking did not significantly improve nitrogen and phosphorus concentrations in the reservoir, whereas sediment reduction had a noticeable effect. Consequently, the management strategies for the Shanzi Reservoir should prioritize external control measures and the implementation of ecological fish stocking. eurmable: cyanobacteria blooms; MIKE 21 Ecolab; measures assess Article  
2024/16  
Water resource managers employ various strategies to minimize the effects of eutrophication, including the diversion of excess nutrients, altering nutrient ratios, physical mixing, and shading water bodies [6]. Additionally, sustainable management practices, such as ecological engineering and biomanipulation, have been developed to mitigate eutrophication and improve water quality in lakes and reservoirs [7]. The overabundance of nutrients, primarily nitrogen and phosphorus, in water starts a process called eutrophication. Algae feed on nutrients, leading to enhanced vegetation growth. This poses significant environmental, economic, and social threats around the world. Good monitoring practices and active management methods are essential to prevent or limit eutrophication in water bodies [8]. In the research on the mechanism of eutrophication in lakes and reservoirs and the direction of pollution control, scholars have conducted extensive and detailed studies on the evaluation of eutrophication levels, analyses of eutrophication influencing factors (nutrient salts, light, hydrology, etc. ), and various physical, chemical, and biological means of algae control [6; 9; 10]. External factors affecting algae growth include not only physical, chemical, and biological factors such as sunlight, nutrient salts, transparency, water temperature, and pH, but also hydrodynamic conditions in the water such as flow velocity, flow rate, and water disturbance [11; 12; 13]. Given the complexity of eutrophication under the influence of multiple ecological environmental factors, people have used the method of establishing mathematical models to assess and manage lake eutrophication [14; 15]. With the development of regression statistical models, total phosphorus mass balance models, phytoplankton mass balance models, as well as ecological dynamic models, the comprehensiveness and systematisms of lake eutrophication models have been gradually improved [16; 17; 18]. The complexity and multi-factor nature of the eutrophication model of lakes and reservoirs have gradually been improved, as well as the related systemic research.