Microcystis aeruginosa (M. aeruginosa), a dominant bloom-forming cyanobacterium, performs efficient photosynthetic carbon fixation and in situ aerobic methane (CH4) production simultaneously, playing a significant role in regulating the carbon source-sink in inland waters. However, how CO2 scenarios and nutrient levels interact to regulate the carbon fixation and emission of M. aeruginosa remains unclear. Here, we conducted a fully crossed experiment with three atmospheric CO2 concentrations (ambient 420 ppm, 650 ppm, and 1000 ppm) and three nutrient levels to explore growth, photosynthesis, and carbon metabolism responses in M. aeruginosa. Results showed that algal growth and carbon fixation exhibited nutrient-dependent positive responses to elevated atmospheric CO2. High-nutrient conditions amplified CO2 fertilization effects, whereas nutrient limitation eliminated such benefits and aggravated photoinhibition. Aerobic CH4 production peaked within meso-oligotrophic systems, and elevated atmospheric CO2 further enhanced CH4 emission efflux and dissolved CH4 concentration, weakening the net carbon sink efficiency. We demonstrated that nutrient availability acts as a critical threshold factor governing CO2-driven carbon partitioning and carbon sink contribution, and evaluating carbon sinks merely by carbon fixation flux will lead to overestimation. This study advanced the inland water carbon cycle theory and provided a scientific basis for greenhouse gas accounting, bloom control, and aquatic carbon sink enhancement under global change.

Environmental factors are widely assumed to influence nitrogen (N) cycle processes in lakeside wetlands. However, recent studies suggested that shifts in environmental conditions do not consistently correspond to proportional changes in N-functional potential. To elucidate the contributions of different drivers, multiple influences, including environmental factors, microbial diversity, functional microbial genera, and gene abundance, were examined by integrating a random forest model (RFM), variation partitioning analysis (VPA), network co-occurrence analysis, and structural equation modeling (SEM). Almost 66 % of functional genes in RFM analysis exhibited a preferable R2 fit over 0.6. VPA analysis revealed that functional microbial genes (55.1 %) and genera (35.1 %) accounted for over 90 % of the explanatory contribution rate, surpassing environmental influences (4.3 %) and diversity indices (5.4 %). Network co-occurrence demonstrated that denitrification genes (norB/C/D/E; napA) formed central connective nodes in the network linked to nitrogen-cycle functional potential, and functional genera-gene linkages were closely aligned with variations in N-functional potential. SEM results further revealed that environmental factors did not exhibit a significant direct association with functional genes; instead, their effects were mediated indirectly through the restructuring of microbial community composition. Under long-term hydrological and nutrient fluctuations, microbial communities exhibited internal co-occurrence networks that were associated with N-cycle functional potential. Recognizing these internally structured microbial associations provides new insight into microbial contributions to N-cycle functional potential and may guide the design strategies of sustainable lakeside wetland restoration.

Lakeside wetlands play a critical role in mitigating non-point source nitrogen (N) pollution, yet the mechanisms underlying vertical microbial stratification across the water-sediment interface remain unclear. Based on a single dry-season sampling campaign conducted in February 2023, microbial communities and N-cycling functional genera exhibited a clear depth-dependent stratification under hydrological fluctuation, but their responses were not vertically synchronized. The sediment profile functioned as a three-tier system, shifting from disturbance-buffered surface processes to subsurface-dominated regulation: weak soil-microbe coupling in surface layers (0-10 cm), coupling between soil and microbial indicators strengthened at intermediate depths (10-40 cm), and soil-mediated control became more evident in the lower-profile layer (40-50 cm). Environmental effects emerged at 20-30 cm, whereas microbial network connectivity peaked at 30-40 cm, suggesting a delayed and partially dissociated relationship. Denitrifying taxa showed a weak V-shaped depth distribution, with the highest relative abundance in the top 5 cm (32.5% ± 17.0%) and a minimum at 10-20 cm (23.8% ± 14.1%). Soil parameters explained most of the community variation, while vegetation and hydrological factors contributed less. These findings identified the intermediate layer (10-40 cm) as a critical functional zone for N transformation, while the lower-profile layer (40-50 cm) may retain residual denitrification-related potential under resource-limited conditions. These findings suggested that subsurface soil-microbe interactions should be considered when evaluating dry-season N-cycling potential in the lakeside wetlands, although their temporal stability and actual functional activity require further verification.

Microcystis aeruginosa (M. aeruginosa) blooms threaten aquatic ecosystems and drinking water safety. Algicidal bacteria offer an eco-friendly approach to control Microcystis blooms, yet few strains can simultaneously inhibit algae growth and reduce microcystin production. Herein, we isolated an efficient algicidal bacterium Pseudomonas fulva EH5 and explored its inhibitory effects and underlying mechanisms against M. aeruginosa. Strain EH5 exerted prominent algicidal activity mainly via secreted active substances, with a 97.33% inhibition rate at a 4% inoculation ratio on day 5. EH5 displayed high algicidal activity against harmful cyanobacteria, while exerting limited adverse impacts on non-target algae and zebrafish. Rather than causing widespread lysis of M. aeruginosa cells, EH5 inflicted severe damage to intracellular thylakoid structures. In addition, EH5 markedly repressed the expression of microcystin synthesis genes and reduced microcystin contents. The algicidal substances of EH5 were presumed to be intracellular-targeting polypeptides with strong acid‑base stability. The algicidal effect of EH5 against M. aeruginosa might be primarily attributed to its impairment of the photosynthetic system. Meanwhile, mild oxidative stress induced by EH5 might serve as a synergistic factor to accelerate algal suppression. Collectively, strain EH5 is a promising candidate for the ecological control of Microcystis blooms and microcystin pollution.

Algae play an important role in lake ecosystems, and algal succession is vital to studying the mechanism of algal bloom outbreaks. This paper provides a comprehensive review of algae blooms development, bloom-forming algae succession, the diversity of common blooms-forming algae, and key drivers for algae succession in Chinese lakes, based on an extensive literature survey and data sets. Furthermore, it summarizes the influencing factors for algae blooms and bloom-forming algae succession in five lake zones of China. The results indicated that the number of research publications on algal blooms in China constituted the largest share of global research, representing 41.9 %. The predominant types of algae blooms in all publications were cyanobacterial blooms, followed by dinoflagellate blooms. The blooms-forming algae in China's lakes have experienced a clear succession pattern: Bacillariophyta, Chlorophyta and Pyrrophyta were dominated in the initial investigations; dominance of Microcystis, Anabaena, dinoflagellates and diatoms increased significantly since1960s; in the past decade, Cylindrospermopsis and dinoflagellates expanded. Current research on algae blooms in Chinese lakes mainly focuses on cyanobacterial blooms, especially Microcystis blooms, while researches on filamentous cyanobacterial blooms and other algae blooms is still insufficient. This systematic review will help researchers to understand the basic features such as the occurrence, the diversity, the physio-ecology and the driving factors of common blooms-forming algae, will further provide a scientific basis for their control in various lake regions.

Qionghai Lake is an important freshwater source in the Yunnan–Guizhou Plateau. However, cyanobacterial blooms have been observed recently in Qionghai Lake, but their formation mechanism and control management are not well understood. Herein, phytoplankton, zooplankton, eutrophication, nutrients, and biochemical indices were measured in Qionghai Lake from May 2022 to April 2023. The results showed that cyanobacterial blooms in Qionghai Lake predominated in Anabaena sp. with a density of 1.11 × 107–18.87 × 107 cells/L. Anabaena blooms started in the northwestern area of Qionghai Lake in November 2022 and then expanded to the entire lake until it peaked and subsided in February 2023. Protozoa dominated in zooplankton while having no significant relationship with Anabaena blooms in Qionghai Lake. The trophic level index and chlorophyll a showed similar spatiotemporal trends with Anabaena sp. density, and water quality in the northwest of the Qionghai Lake was worse than in other parts. Total nitrogen (TN) and total phosphorus (TP) were 0.41–0.54 and 0.021–0.045 mg/L from November 2022 to February 2023. TN and TP were positively correlated with Anabaena sp. density, but TP was the most significant environmental factor affecting Anabaena bloom in Qionghai Lake. These findings might provide essential information for improving bloom control and water quality remediation in Qionghai Lake.

Spring dinoflagellate blooms are always severe in the Three Gorges Reservoir (TGR), China, threatening water ecological health. Many dinoflagellates are capable of mixotrophism, yet the influence of dissolved organic matter (DOM) on their growth and blooms in spring remains unclear. This study characterized the source and composition of DOM from sediment, soil, and plant, and assessed their effects on the growth of bloom-forming algal species (Peridiniopsis sp. and Microcystis aeruginosa) under different temperatures. The results showed that sediment and soil DOM promoted Peridiniopsis sp. growth, plant DOM slightly inhibited it. However, DOM had no significant effect on M. aeruginosa growth. The promotion of sediment and soil DOM on Peridiniopsis sp. growth was higher at 15 °C and 20 °C than at 25 °C. Moreover, the effect of DOM on Peridiniopsis sp. growth was more significant than that of high nitrogen and phosphorus. Fulvic acid-like, humic-like and tyrosine-like substances of DOM in sediment and soil might be the effective components promoting the Peridiniopsis sp. growth, while tryptophan-like substance of plant DOM might hinder it. Sediment and soil DOM might promote the Peridiniopsis sp. growth mainly by providing adequate organic carbon, increasing protein content, and improving photosynthesis. The findings will provide important information for the formation and control of dinoflagellate blooms in TGR.

Cyanobacterial blooms pose one of the most severe ecological challenges in aquatic systems. However, the mechanism through which bacterial dissolved organic matter influences the formation of algal blooms remains unclear. In this study, extracellular organic matter (EOM) was extracted from Flavobacterium sp., a common bacterial group in bloom, and the impacts of this EOM on the growth, physiology, photosynthesis, and transcriptome of Anabaena sp. were investigated. The results indicated that flavobacterium-derived EOM (F-EOM) inhibited Anabaena sp. growth, physiological activity, and photosynthesis, with greater inhibition at higher concentrations. Meanwhile, transcriptome analysis showed that 803 genes in Anabaena sp. were differentially expressed after being exposed to 10 mg/L F-EOM, with simultaneously the majority being down-regulated. The down-regulation of genes in photochemical reactions, the synthesis of photosynthetic pigment, and light-trapping antenna protein inhibited photosynthesis. While ATP synthesis was reduced due to the genes related to oxidative phosphorylation and the tricarboxylic acid cycle was downregulated. Moreover, the down-regulated genes in amino acid synthesis affected the synthesis of proteins and metabolic regulatory factors. This may be the main reason why F-EOM could hinder the growth and metabolism of Anabaena sp. These results provide scientific insights into the formation and control of cyanobacteria blooms.

The landscape configuration of lakeside wetlands plays a pivotal role in mediating water purification, making it essential to investigate how ecological restoration in the wetlands around lakeshore reshapes these patterns to improve water quality. In this study, the effectiveness of a restored plateau lakeside wetland in water purification capacity was evaluated by analyzing the geographical variation of contaminant concentrations from inlets to outlets and identifying potential key landscape factors affecting purification capacity. The results showed that the average removal efficiencies of total nitrogen, total phosphorus, and permanganate index were 63.76 %, 71.10 %, and 28.74 %, respectively, demonstrating the significant capability of the restored lakeside wetland in nutrient removal and water purification. Redundancy analysis and variation partitioning analysis indicated that interface properties had the greatest impact on purification capacity (28.1 %), followed by the synergistic effect of structural parameters and habitat elements for land use (16.3 %), and the independent effect of habitat elements for land use (13.2 %) and structural parameters (12.2 %). Among them, gentle slopes were found to significantly enhance nitrogen retention (p < 0.05). The vegetated interface areas with complex community structures significantly enhanced nutrient removal, justifying the strategic construction of grassland-water and forest-water interfaces in lakeside wetlands to maximize contaminant mitigation. These findings established actionable frameworks for optimizing lakeside wetland restoration through targeted landscape configuration and management, thereby significantly enhancing long-term water quality protection in lake ecosystems.

The linkages of distributed ponds are utilized in conjunction with one another to remediate non-point source (NPS) pollution in a water-scarce basin. This study provides an overview of a state-of-the-art thorough evaluation of ponds, which offers insight into the majority of topics covered by the ongoing scientific studies, including their various functions and factors affecting their functioning on the hydrological, physicochemical, and biological processes, such as environmental climate factors and basin-specific landscape configuration parameters, as well as process parameters for design, operation and management aspects. The linkages of ponds provide a variety of sustainable services (6R functions), such as resources, restoration, reduction, reuse, recycling, and recovery. The significance of regional environmental geochemical substrates in the ponds, such as red soil, as a hotspot for microbial reaction is emphasized to demonstrate the significant contribution of the migration and transformation of Fe/N cycles to the pollution removal process. In this review, 178 original research publications were thoroughly analyzed to improve our knowledge of the iron-nitrogen cycle in wetlands. From a molecular biology standpoint, the identification of functional microbe species and genes linked to microbially driven iron-nitrogen cycle activities is delved. Reliable data and homogeneous datasets from 42 studies were collected. The correlation analysis results demonstrated Feammox rates contributed to the N loss amount (r = 0.871; p < 0.01), and they had a positive correlation with Fe(III) concentration (r = 0.965; p < 0.01). The proposal for the treatment of NPS pollution by large-scale linkages of ponds in a basin involves optimizing Fe/N microbial processes to promote iron crystallization and efficient circulation of Fe(II) and Fe(III). The co-benefits of geochemistry, biotechnology, and environmental science should be considered when managing contamination in engineering applications. The linkages framework for integrated ponds, which incorporates macro (watershed management) and micro (biogeochemical cycle mechanism) investigations, provides a systematic approach to the application of integrated ponds and sustainable water management for NPS pollution control.

The phytoplankton population of Qionghai Lake was surveyed in December 2015, March 2016, June 2016, September 2016, and March 2017. A total of 196 species (including varieties) belonging to 77 genera of 7 phyla were identified. The phytoplankton communities were dominated by Chlorophyta and diatoms, and there were significant differences across the five sampling sites. The phytoplankton abundance, which ranged between 13.85 × 104 and 335.54 × 104 cells·L−1, was significantly higher in spring and summer than in autumn and winter. Chlorella sp. and Cyclotella sp. were the dominant populations, and their dominance degree reached as high as 0.54 and 0.33, respectively. The diversity of the phytoplankton populations was significantly higher in spring and summer than in autumn and winter, and the Shannon–Wiener index and Margalef index ranged from 2.49–3.65 and 2.47–3.10, respectively. The water quality of Qionghai Lake was generally good. The trophic level index was between 30 and 60, showing that the water body was overall in a mesotrophic to slightly eutrophic state. The Spearman correlation analyses revealed that ammonium nitrogen (NH4+-N), water temperature (WT), permanganate index (CODMn), and transparency (SD) were the most important environmental factors that influenced the phytoplankton communities. For example, NH4+-N was significantly correlated with Chroococcus sp. (r = 0.41, p < 0.05) and Cryptomonas ovata Ehrenberg (r = 0.45, p < 0.05), and WT was significantly correlated with Cryptomonas marssonii Skuja (r = 0.43, p < 0.05) and Cryptomonas ovata (r = 0.53, p < 0.01).

Polychlorinated biphenyls (PCBs) were continuously receiving attention after their ban for use and production, owing to significant persistence, transport, and toxicity at trace level. Due to the field data gap of all 209 PCB congeners in previous studies, the source and environmental migration of lacustrine PCBs were not comprehensively understood. In this study, 209 PCB congeners in 277 water and 155 sediment samples collected from China’s 23 large lakes across a longitudinal transect (18–45 °N) were analyzed. Results showed that the concentrations of Σ209PCBs were 0.03–41.04 ng/L and 0.26–163.82 ng/g dry weight in lake water and sediment, respectively. In lake water, the dominant PCB congeners, detected in over 50% of all samples, were PCB 11, PCB 28+31, PCB 41+64+68, PCB 47+48+75, and PCB 51, with contributions to Σ209PCBs as 39.8%, 6.6%, 3.5%, 18.4%, and 6.4%, respectively. Source apportionment revealed that major contributions of PCB 11, 41+64+68, 47+48+75, 51, and 209, were mainly from unintentionally produced PCBs (UP-PCBs) while PCB 28+31 and the other congeners from historical PCB commercials. Therefore, the selective congener analysis (excluding UP-PCBs) common in previous lake studies was an omission. Simultaneously, the longitudinal fractionation of PCBs was also found in lake waters, likely caused by the East Asian monsoon. Moreover, fugacity fractions of PCBs between water and sediment indicated their overall equilibrium or net sorption. Overall, PCB 28+31 can be well indicative of PCB migration. This study provides basic information for the migration and transformation of trace toxic persistent organic pollutants.

This study analyzed the spatiotemporal distribution characteristics, ecological risks, biological toxicity, and sources of Cu, Zn, Pb, Cd, Hg, and As in the surface sediments of Dongting Lake, as well as the response of benthic macroinvertebrates to these pollutants. Among the three lake regions, the concentration of Cu, Zn, Pb, Cd, and As fell in the order of South Dongting Lake (SD) > East Dongting Lake (ED) > West Dongting Lake (WD), whereas the concentration of Hg fell in the order of WD > SD > ED. The concentrations of Cu, Zn, Pb, and As were 1.69-2.02 times the background values recorded in 1986, whereas the concentrations of Cd and Hg were 8.97 and 5.32 times the background values, respectively. The ecological risk was low for Cu, Zn, Pb, As but high for Hg and Cd. For Dongting Lake in aggregate, the heavy metals caused considerable ecological risk and high biotoxicity, although the situation was improving in recent years. Cd, As, Cu, Pb, Hg were mainly from agricultural sources, mining sources, tire wear and agricultural sources, industrial smelting and mining sources, industrial processing and smelting sources, respectively, and Zn was from mixed sources. A total of 66 species of benthic macroinvertebrates were identified from the sediments. From 2018 to 2022, the dominant benthic macroinvertebrates gradually shifted from the pollution-resistant in Tubificidae to those in Gammarus, Bellamya, Valvatidae, etc. Oligochaetes and Stictochironomus spp. exhibited extremely high response to heavy metals and could serve as indicator organisms of heavy metal pollution.

Understanding the occurrence, sources, and ecological risks of polychlorinated biphenyls (PCBs), which are universal persistent organic pollutants, is critical for improving the sustainability and ecological safety of lake systems. Herein, to determine PCB contamination levels and formulate control strategies in lake sediments, 210 sediment samples were collected from 21 lakes along a latitudinal gradient (18-45 degrees N, similar to 3000 km) across eastern China and were analyzed for all 209 PCB congeners. The results showed that the total PCB concentration varied greatly from 0.26 to 163.82 ng/g dry weight and exhibited a latitudinal trend of central > north/south. Spatial variations were affected mainly by the organic carbon fraction and local population density. Most lakes had similar PCB profiles, with lower chlorinated PCBs dominating. Notably, non-Aroclor PCB 11 was the most abundant congener. Moreover, unintentionally produced PCBs (UP-PCBs) accounted for similar to 31 % of all PCBs. These findings highlight that the significance of UP-PCBs has been overlooked in past studies and that full-congener analysis is necessary for future monitoring. According to the ecological risk assessment of PCBs, zero to moderate risk existed in lake sediments. Therefore, effective strategies are needed to mitigate the impact of PCBs (especially UP-PCBs) from multiple sources on lakes.

Lake Qionghai,the second largest lake in Sichuan,is located＜5 km away from Xichang City,with an important ecolog-ical meaning.Based on continuous monitoring data over the past 20 years,this work studied the historical changes of the water eco-logical environment,and established the spatiotemporal correspondence of water quality parameters and nutritional status indicators in Lake Qionghai.The results showed:(1)The water quality was the worst during the period of 1980s-2000,with total nitrogen(TN)and total phosphorus(TP)concentrations far exceeding the Class Ⅲ standard for surface water.(2)Since 2003,the intera-nnual variation of ammonia nitrogen(NH3-N)and CODMn concentrations in the Lake Qionghai had shown an overall downward trend,while the interannual variation trend of TN,TP,transparency,and dissolved oxygen values was generally insignificant.The concentrations of CODMn,TN,and TP showed a series of significant changes.(3)Since 2003,the trophic status of Lake Qionghai had been at a moderate level,with trophic state index(TLI(∑))of 33.82±6.88 and chlorophyll-a(Chl.a)concentration of(4.234±3.903)μg/L.There was no significant trend in the interannual variation of TLI(∑)and Chl.a.(4)The water quality in the area around Qionghai Hotel was the worst,and the water quality in the center of Lake Qionghai was the best.Since 2003,the maximum monthly concentrations of CODMn,TP and other indicators had allappeared in the water area where Qionghai Hotel was located.(5)The concentrations of CODMn in the dry season was significant lower than that in the wet season,and the concentration of NH3-N in the dry season was significant higher than that in the wet season.High and low concentrations of TP occurred during the dry season,and there was no significant difference in monthly concentrations of TN.Chl:a concentration had a significant posi-tive correlation with TP concentration,but there was no significant correlation with TN.Phosphorus was the first controlling factor that restricts algae growth in Lake Qionghai.(6)Pollution from non-point source pollution entered in Lake Qionghai mainly through tributaries.The reduction effect of the wetland around the Lake Qionghai on the non-point source pollution was limited.There would be a high risk of water blooms in the Lake Qionghai in the future.It is recommended to promote the control of land-based pollution in small watersheds,layout tourism development according to the concept of"tourism in the Lake Qionghai,eating and living in Xichang urban areas",and explore the use of a"physical+ecological"approach to regulate and prevent the imbalance of the Lake Qionghai ecosystem.

Initial flush management is an effective measure to control non-point source pollution (NPSP) in storm runoff. However, determining the parameter of the initial flush in different areas may pose challenges in storm runoff management strategies. To address this issue, Erhai Lake in China, Yunnan-Guizhou Plateau, was selected as an example for the study. Erhai Lake is a typical mesotrophic lake with the profound influence of NPSP. The NPSP control strategy in this area will provide a valuable reference for other lakes. In 2021, 289 storm events and 190 ditchwater samples were detected around Erhai Lake. The average flow in the ditches ranged from 0.004 to 0.147 m3/s, the instant total nitrogen (TN) concentration ranged from 0.28 to 91.43 mg/L, and the instant total phosphorus (TP) concentration ranged from 0.26 to 7.35 mg/L in the storm events. It was found that the concentration of pollutants was lower than expected in the initial flush period. Instead, the event mean concentrations of TN and TP were 9.3 and 2.1 times higher than in the wet seasons, showing high nutrient concentration levels throughout the entire rainfall period. To manage storm runoff effectively, a flow-processes-division method was proposed to analyze the inflow condition and pollutant removal rate in different runoff periods. The peak flow interception strategy was recommended as the optimal stormwater management plan, as it showed the highest inflow conditions and 50% pollutant removal rate. Considering the need to reduce the constant flush of stormwater runoff, it is essential to establish a healthy water cycle system to alleviate NPSP and raise the Erhai water level. The storm runoff management method can serve as a practical tool for lake areas that do not exhibit initial flush characteristics.

Organophosphates(OPEs)are widely used as flame retardants and additives and thus are commonly detected in the environment.In order to explore their environmental behavior,the concentrations of 13 OPEs in the surface water and sediment of Dongting Lake were analyzed using UPLC-MS/MS.The results showed that 11 OPEs were detected,with detection frequencies of 5.26%-100%and 58.3%-100%,and the concentrations of OPEs were 2.06-2028 ng·L-1 and 19.6-2232 ng·g-1 in water and sediment,respectively.Overall,contamination concentrations were ranked in descending order as follows:inflowing rivers,lake area,and outlet,whereas the spatial distribution of concentrations in sediment was inversely proportional to hydrodynamics.The concentration of OPEs in Dongting Lake was at a high level compared with that of domestic and foreign lakes.Among the detected 11 OPEs,tri-iso-butyl phosphate(TnBP)and(TiBP)were dominant in water,accounting for 52.3%and 22.4%of ∑OPEs,respectively.TPhP was the dominant OPEs in sediment,accounting for 31.2%of ∑OPEs.The correlation and principal component analysis indicated that OPEs pollution in Dongting Lake was mainly affected by industrial production emissions,fishery aquaculture,and atmospheric deposition.The assessment results of the risk entropy showed that most of the detected OPEs in water had relatively low ecological risks,whereas the ecological risk of 2-ethylhexyl diphenyl phosphate(EHDPP)at some sampling points requires further attention.

This study carried out an investigation on macrophytes of Lake Qionghai in July and December 2021, and May and September 2022. Based on the investigation results and previous publications, this study examined the species compositions, community structure, spatial distribution, and causes of degradation of macrophytes. The investigation revealed that there were 23 species of macrophytes in Lake Qionghai, mainly found in water area less than 2 m deep, covering an area of about 1.3 km2. The distribution of macrophytes was mainly in the north, with patchy distribution in the west and south, and scattered in the east. However, the areas had decreased to less than 5% of the lake from 20% before the 1990s. The community structure of submerged plants had become simplified, while the distribution ranges of floating plants and emergent plants expanded. The disappearance of submerged vegetation in Gaojian Bay was caused by a flood from the mouth of the Hai River in 1998. Additionally, higher water-level operations and lower transparency in the last ten years had resulted in the decreased distribution areas and simplified communities of macrophytes in Lake Qionghai. To restore the macrophytes in Lake Qionghai, we recommend implementing measures to restore the natural rhythm of the water level and reduce pollution load input to improve water transparency. At the same time, artificial ecological restoration is also needed to restore the ecosystem's health.