Comparison of three flocculants for heavy cyanobacterial bloom mitigation and subsequent environmental impact

Cyanobacteria can accumulate as a heavy biomass on the leeward side of large eutrophic lakes,posing a potential threat to public health.The mitigating capacity of three flocculants and their potential impacts on the major environmental features of water and sediments was evaluated.Results indicate that polyaluminum chloride(PAC)and ferric chloride(FeCl)are efficient flocculants that can rapidly mitigate cyanobacterial blooms with chlorophyll-a concentrations higher tnan 1500 ug/L within 15 min.In comparison,cationic starch with chitosan could only treat cyanobacterial blooms in chlorophyll-a concentrations of less than 200μg/L.The addition of FeClcaused a decline in the pH value,while dissolved oxygen in the water column dropped to 2 mg/L during cationic starch with chitosan treatment for a high cyanobacterial biomass group.Thus,a combination of flocculants and oxygenators should be considered when treating high-concentration cyanobacterial blooms for emergency purposes.Additionally,the cell lysis of cyanobacteria caused by cationic starch with chitosan can result in an increase in total dissolved phosphorus and total dissolved nitrogen.Furthermore,the high accumlation of nutrients in sediments after the settling of cyanobacteria can cause high internal phosphorus pollution.The increase in the total organic carbon of the sediments can threaten lake restoration achieved by planting submerged macrophytes.

Bioremediation of Acetochlor in Soil and Water Systems by Cyanobacterial Mat

This study investigated the bioremediation of organic pollution in soil and water systems by cyanobacterial mats collected from Wadi Gaza. Acetochlor, a model compound of herbicide, was used as a standard organic pollutant. Various concentrations of acetochlor were injected in soil and water samples pre-treated with cyanobacterial mat for several periods of time. Percentage of growth of wheat as a test plant was taken as indicator of bioremediation of acetochlor. Results showed that acetochlor was degraded in both soil and water systems. Degradation was?much?faster in the water system than in the soil system. Concentrations of acetochlor above the field rate did not affect the bioremediation process in the water system whereas it did in soil pots. Furthermore, bioremediation in water system was nearly completed in 15 days whereas it did not reach high percentage?in the soil system. These encouraging results are new contribution in field of bioremediation of pesticide by cyanobacterial mats and suggest that application of cyanobacterial mat could be a fast and suitable methodology for bioremediation of organic pollutant in the ecosystem.

Tidal water exchanges can shape the phytoplankton community structure and reduce the risk of harmful cyanobacterial blooms in a semi-closed lake

For estuaries,inland lakes play a vital role in the ecological balance under the impact of tide s.The effect of tides-induced water exchange on phytoplankton community in a semi-closed lake was studied and compared with that of an adjacent closed lake in the Oujiang River mouth in Zhejiang,East China Sea,from June 29,2020 to June 14,2021.Results show that the dominant species,abundance,dominance,and diversity of the phytoplankton species between the two lakes were significantly different.In the closed lake,cyanobacteria were the dominant species during the study period.However.in the semi-closed lake,the diversification of the dominant species was greater,and some species of diatoms and green algae became dominant.The average phytoplankton abundance in the closed lake was 6 times of that in the semi-closed lake.The average dominance of cyanobacteria in the closed lake was 0.96,and those in the semi-closed lake and the Oujiang River were 0.51 and 0.22,respectively.Cyanobacterial blooms occurred throughout the study time in the closed lake but not in the semi-closed one.Furthermore,the species diversity richness of the phytoplankton in the semi-closed lake was higher than that of the closed one,and the phytoplankton community between the closed lake and semi-closed lake could be divided into distinctly different groups based on non-metic multidimensional scaling analysis(NMDS)and analysis of similarities(ANOSIM)analysis.The salinity of the water was significantly greater and the transparency significantly smaller in the semi-closed lake than those in the closed lake.Therefore,water exchange driven by local tidal movement increased salinity and decreased transparency of water,which consequently shaped the community structures of different phytoplankton and reduced the risk of a cyanobacterial bloom outbreak in the semi-closed lake.

Bioremediation of Diuron in Soil Environment: Influence of Cyanobacterial Mat

Diuron is a herbicide widely used in the Middle East;its field application creates many environmental problems. This study investigated the bioremediation of Diuron in soil environment by Cyanobacterial mats collected from Gaza Wadi. Various concentrations of Diuron were injected in water saturated soil samples pre-treated with Cyanobacterial mat for several periods. Percent growth of Jews mallow as a test plant was taken as indicator of biodegradation of Diuron. Results showed that Diuron was degraded in soil and degradation was more pronounced when Diuron was incubated with Cyanobacterial in the irrigation water. Larger applied rate of Cyanobacterial mat did not affect the biodegradation of Diuron. These encouraging results suggest that application of Cyanobacterial mat could be a suitable method to remediate soil pollution.

Snowpack shifts cyanobacterial community in biological soil crusts

Winter snowpack is an important source of moisture that influences the development ofbiological soil crusts(BSCs)in desert ecosystems.Cyanobacteria are important photosynthetic organismsin BSCs.However,the responses of the cyanobacterial community in BSCs to snowpack,snow depth andmelting snow are still unknown.In this study,we investigated the cyanobacterial community compositionand diversity in BSCs under different snow treatments(doubled snow,ambient snow and removed snow)and three snow stages(stage 1,snowpack;stage 2,melting snow;and stage 3,melted snow)in theGurbantunggut Desert in China.In stages 1 and 2,Cyanobacteria were the dominant phylum in the bacterialcommunity in the removed snow treatment,whereas Proteobacteria and Bacteroidetes were abundant inthe bacterial communities in the ambient snow and doubled snow treatments.The relative abundances ofProteobacteria and Bacteroidetes increased with increasing snow depth.The relative abundances ofCyanobacteria and other bacterial taxa were affected mainly by soil temperature and irradiance.In stages 2and 3,the relative abundance of Cyanobacteria increased quickly due to the suitable soil moisture andirradiance conditions.Oscillatoriales,Chroococcales,Nostocales,Synechococcales and unclassifiedCyanobacteria were detected in all the snow treatments,and the most dominant taxa were Oscillatorialesand Chroococcales.Various cyanobacterial taxa showed different responses to snowpack.Soil moisture andirradiance were the two critical factors shaping the cyanobacterial community structure.The snowpackdepth and duration altered the soil surface irradiance,soil moisture and other soil properties,whichconsequently were selected for different cyanobacterial communities.Thus,local microenvironmentalfiltering(niche selection)caused by snow conditions may be a dominant process driving shifts in thecyanobacterial community in BSCs.

Dynamic behavior of the cyanobacterial circadian clock with regulation of CikA

Cyanobacteria are the simplest organisms to have circadian clocks.The central oscillator in cyanobacteria is composed by a transcriptional/translational feedback loop(TTFL)and a post-translational oscillator(PTO).The PTO is a core pacemaker which consists of three proteins KaiA,KaiB and KaiC.KaiA stimulates the phosphorylation of KaiC,while KaiB inhibits the activity of KaiA.The cyanobacterial circadian clock is an interesting topic for researchers and many mathematical models have been constructed.However,the current mathematical models of the cyanobacterial circadian clock have been made only considering the interactions between Kai proteins.CikA,as an input pathway component,plays an essential role in the circadian clock,whose mutation results in abnormal rhythms.The regulation mechanism of CikA remains unclear.In this paper,we develop a detailed mathematical model for the cyanobacterial circadian clock with incorporation CikA-regulation.Based on numerical simulations,we explore the dynamic properties of the circadian clock regulated by CikA.The results show that the regulation of CikA makes the system more sensitive.In detail,CikA strengthens the central role of PTO and improves the adaptability of the circadian clock against the change of environment.With CikA,the system is able to modulate its period more easily to face environmental perturbation.CikA also enhances slightly the fitness of cyanobacteria.The findings of this paper can supplement the biological research and may help us more clearly understand the cyanobacterial circadian clock regulated by other proteins.

Entrainment mechanism of the cyanobacterial circadian clock induced by oxidized quinone

The circadian clock is a self-sustained biological oscillator which can be entrained by environmental signals.The cyanobacteria circadian clock is the simplest one,which is composed of the proteins KaiA,KaiB and KaiC.The phosphorylation/dephosphorylation state of KaiC exhibits a circadian oscillator.KaiA and KaiB activate KaiC phosphorylation and dephosphorylation respectively.CikA competing with KaiA for the same binding site on KaiB affects the phosphorylation state of KaiC.Quinone is a signaling molecule for entraining the cyanobacterial circadian clock which is oxidized at the onset of darkness and reduced at the onset of light,reflecting the environmental light-dark cycle.KaiA and CikA can sense external signals by detecting the oxidation state of quinone.However,the entrainment mechanism is far from clear.We develop an enhanced mathematical model including oxidized quinone sensed by KaiA and CikA,with which we present a detailed study on the entrainment of the cyanobacteria circadian clock induced by quinone signals.We find that KaiA and CikA sensing oxidized quinone pulse are related to phase advance and delay,respectively.The time of oxidized quinone pulse addition plays a key role in the phase shifts.The combination of KaiA and CikA is beneficial to the generation of entrainment,and the increase of signal intensity reduces the entrainment phase.This study provides a theoretical reference for biological research and helps us understand the dynamical mechanisms of cyanobacteria circadian clock.

The Correlation between the Variation of Dissolved Inorganic Carbon Content and Cyanobacterial Blooms in Fubao Bay of Dianchi Lake

To explore variation of dissolved inorganic carbon content( DIC) caused by cyanobacterial blooms and provide a basis for formulating effective preventive and control measures of cyanobacterial blooms,the concentration of inorganic carbon and the concentration of planktonic algae were studied by sampling method,and the distribution and variation of the DIC and physicochemical factors in the ecological restoration area of Fubao Bay of Dianchi Lake were analyzed. Results indicated that the distribution of chlorophyll-a was significantly positive correlated with CO_3^(2-)( P < 0. 01) and pH values( P < 0. 05); and the distribution of chlorophyll-a was significantly negative correlated with CO_2( P <0. 01),DIC and HCO_3^-( P < 0. 05). In conclusion,the outbreak and extinction of cyanobacterial blooms is one of the important reasons for the variation of inorganic carbon form and concentration.

Green Liver Systems for Water Purification:Using the Phytoremediation Potential of Aquatic Macrophytes for the Removal of Different Cyanobacterial Toxins from Water

The protection and reasonable use of freshwater is one of the main goals for our future, as water is most important for all organisms on earth including humans. Due to pollution, not only with xenobiotics, but also with nutrients, the status of our water bodies has changed drastically. Excess nutrient load induces eutrophication processes and, as a result, massive cyanobacterial blooms during the summer times. As cyanobacteria are known to produce several toxic secondary metabolites, the so-called cyanotoxins, exhibiting hepato-, neuro- and cell-toxicity, a potential risk is given, when using this water. There is an urgent need to have a water purification system, which is able to cope with these natural toxins. Using aquatic plants as a Green Liver, the Green Liver System?, was developed, able to remove these natural pollutants. To test the ability of the Green Liver System?, several cyanobacterial toxins including artificial and natural mixtures were tested in a small-scale laboratory system. The results showed that within 7 - 14 days a combination of different aquatic macrophytes was able to remove a given toxin amount (10 μg·L-1) by 100%. The phytoremediation technology behind the Green Liver Systems? uses the simple ability of submerged aquatic plants to uptake, detoxify and store the toxins, without formation and release of further metabolites to the surrounding water.

The Pichia pastoris enzyme production platform:From combinatorial library screening to bench-top fermentation on residual cyanobacterial biomass

The demand for industrial enzymes is continually rising,fueled by the growing need to shift towards more sustainable industrial processes.However,making efficient enzyme production strains and identifying optimal enzyme expression conditions remains a challenge.Moreover,the production of the enzymes themselves comes with unavoidable impacts,e.g.,the need to utilize secondary feedstocks.Here,we take a more holistic view of bioprocess development and report an integrative approach that allows us to rapidly identify improved enzyme expression and secretion conditions and make use of cyanobacterial waste biomass as feed for supporting Pichia pastoris fermentation.We demonstrate these capabilities by producing a phytase secreted by P.pastoris that is grown on cyanobacterium hydrolysate and buffered glycerol-complex(BMGY)medium,with genetic expression conditions identified by high-throughput screening of a randomized se-cretion library.When our best-performing strain is grown in a fed-batch fermentation on BMGY,we reach over 7000 U/mL in three days.

The coupling control of biological precursors and environmental factors onβ-carotane enrichment in alkaline lacustrine source rocks:A case study from the Fengcheng formation in the western Junggar Basin,NW China

The organic-rich mudstones and dolostones of the Permian Fengcheng Formation(Fm.)are typically alkaline lacustrine source rocks,which are typified by impressively abundantβ-carotane.Abundant β-carotane has been well acknowledged as an effective indicator of biological sources or depositional environments.However,the specific biological sources of β-carotane and the coupling control of biological sources and environmental factors on the enrichment of β-carotane in the Fengcheng Fm.remains obscure.Based on a comprehensive investigation of the bulk,molecular geochemistry,and organic petrology of sedimentary rocks and the biochemistry of phytoplankton in modern alkaline lakes,we proposed a new understanding of the biological precursors of β-carotane and elucidated the enrichment mechanism of β-carotane in the Fengcheng Fm.The results show that the biological precursors crucially control the enrichment of β-carotane in the Fengcheng Fm.The haloalkaliphilic cyanobacteria are the primary biological sources of β-carotane,which is suggested by a good positive correlation between the 2-methylhopane index,7-+8-methyl heptadecanes/C_(max),C_(29%),and β-carotane/C_(max)in sedimentary rocks and the predominance of cyanobacteria with abundantβ-carotene in modern alkaline lakes.The enrichment of β-carotane requires the reducing condition,and the paleoredox state that affects the enrichment of β-carotane appears to have a threshold.The paleoclimate conditions do not considerably impact the enrichment of β-carotane,but they have some influence on the water's paleosalinity by affecting evaporation and precipitation.While it does not directly affect the enrichment of β-carotane in the Fengcheng Fm.,paleosalinity does have an impact on the cyanobacterial precursor supply and the preservation conditions.

Effects of sand burial on biomass, chlorophyll fluores-cence and extracellular polysaccharides of man-made cyanobacterial crusts under experimental conditions

Soil cyanobacterial crusts occur throughout the world, especially in the semiarid and arid regions. It always encounters sand burial, which is an important feature of mobile sand dunes. A greenhouse study was conducted to determine the effects of sand burial on biomass, chlorophyll fluorescence and extracellular polysaccharides of man-made cyanobacterial crusts in six periods of time (0, 5, 10, 15, 20 and 30 d after burying) and at five depths (0, 0.2, 0.5, 1 and 2cm). The results indicated that with the increase of the burial time and burial depth extracellular polysaccharides content and Fv/Fm decreased correspondingly and there were no significant differences between 20 and 30 burial days under dif-ferent burial depths. The degradation of chlorophyll a content appeared only at 20 and 30 burial days and there was also no significant difference between them under different burial depths. It was also observed a simultaneous decrease of the values of the Fv/Fm and the content of extracellular poly-saccharides happened in the crusted cyanobacterium Microcoleus vaginatus Gom. It may suggest that there exists a relationship between extracellular polysaccharides and recovery of the activity of pho-tosystem II (PS II) after rehydration.

Remote sensing of cyanobacterial blooms in inland waters: present knowledge and future challenges

Timely monitoring, detection and quantification of cyanobacterial blooms are especially important for controlling public health risks and understanding aquatic ecosystem dynamics. Due to the advantages of simultaneous data acquisition over large geographical areas and high temporal coverage, remote sensing strongly facilitates cyanobacterial bloom monitoring in inland waters. We provide a comprehensive review regarding cyanobacterial bloom remote sensing in inland waters including cyanobacterial optical characteristics, operational remote sensing algorithms of chlorophyll, phycocyanin and cyanobacterial bloom areas, and satellite imaging applications. We conclude that there have many significant progresses in the remote sensing algorithm of cyanobacterial pigments over the past 30 years. The band ratio algorithms in the red and near-infrared(NIR) spectral regions have great potential for the remote estimation of chlorophyll a in eutrophic and hypereutrophic inland waters, and the floating algae index(FAI) is the most widely used spectral index for detecting dense cyanobacterial blooms. Landsat, MODIS(Moderate Resolution Imaging Spectroradiometer) and MERIS(MEdium Resolution Imaging Spectrometer) are the most widely used products for monitoring the spatial and temporal dynamics of cyanobacteria in inland waters due to the appropriate temporal, spatial and spectral resolutions. Future work should primarily focus on the development of universal algorithms, remote retrievals of cyanobacterial blooms in oligotrophic waters, and the algorithm applicability to mapping phycocyanin at a large spatial-temporal scale. The applications of satellite images will greatly improve our understanding of the driving mechanism of cyanobacterial blooms by combining numerical and ecosystem dynamics models.

Controlling cyanobacterial blooms by managing nutrient ratio and limitation in a large hypereutrophic lake: Lake Taihu, China

Excessive nitrogen（N） and phosphorus（P） loading of aquatic ecosystems is a leading cause of eutrophication and harmful algal blooms worldwide, and reducing nutrient levels in water has been a primary management objective. To provide a rational protection strategy and predict future trends of eutrophication in eutrophic lakes, we need to understand the relationships between nutrient ratios and nutrient limitations. We conducted a set of outdoor bioassays at the shore of Lake Taihu. It showed that N only additions induced phytoplankton growth but adding only P did not. Combined N plus P additions promoted higher phytoplankton biomass than N only additions, which suggested that both N and P were deficient for maximum phytoplankton growth in this lake（TN：TP = 18.9）. When nutrients are present at less than 7.75–13.95 mg/L TN and 0.41–0.74 mg/L TP, the deficiency of either N or P or both limits the growth of phytoplankton. N limitation then takes place when the TN：TP ratio is less than 21.5–24.7（TDN：TDP was 34.2–44.3）, and P limitation occurs above this. Therefore, according to this ratio, controlling N when N limitation exists and controlling P when P deficiency is present will prevent algal blooms effectively in the short term. But for the long term, a persistent dual nutrient（N and P） management strategy is necessary.

Decrease of NH_4^+-N by bacterioplankton accelerated the removal of cyanobacterial blooms in aerated aquatic ecosystem

We used aerated systems to assess the influence of the bacterioplankton community on cyanobacterial blooms in algae/post-bloom of Lake Taihu, China. Bacterioplankton community diversity was evaluated by polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE） fingerprinting. Chemical analysis and nitrogen dynamic changes illustrated that NH4＋-N was nitrified to NO2^--N and NO3^--N by bacterioplankton. Finally, NHa^＋-N was exhausted and NO3^--N was denitrified to NO2^--N, while the accumulation of NO2^--N indicated that bacterioplankton with completely aerobic denitrification ability were lacking in the water samples collected from Lake Taihu. We suggested that adding completely aerobic denitrification bacteria （to denitrify NO2^--N to N2） would improve the water quality. PCR-DGGE and sequencing results showed that more than 1/3 of the bacterial species were associated with the removal of nitrogen, and Acidovorax temperans was the dominant one. PCR-DGGE, variation of nitrogen, removal efficiencies of chlorophyll-a and canonical correspondence analysis indicated that the bacterioplankton significantly influenced the physiological and biochemical changes of cyanobacteria. Additionally, the unweighted pair-group method with arithmetic means revealed there was no obvious harm to the microecosystem from aeration. The present study demonstrated that bacterioplankton can play crucial roles in aerated ecosystems, which could control the impact of cyanobacterial blooms in eutrophicated fresh water systems.

Off-flavor compounds from decaying cyanobacterial blooms of Lake Taihu

The effect of cyanobacterial bloom decay on water quality and the complete degradation of cyanobacterial blooms in a short period were examined by an enclosure experiment in Gonghu Bay of Lake Taihu,China.Water quality parameters as well as taste and odor compounds during the breakdown of cyanobacterial blooms were measured.Results showed that the decay of cyanobacterial blooms caused anoxic water conditions,decreased pH,and increased nutrient loading to the lake water.The highest concentrations of dimethyl sulfide （DMS）,dimethyl trisulfide （DMTS）,and β-cyclocitral were observed in the anoxic water,at 62331.8,12413.3,and 1374.9 ng/L,respectively.2-Methylisoborneol was dominant during the live growth phase of cyanobacterial blooms,whereas DMS and DMTS were dominant during the decomposition phase.Dissolved oxygen,pH,and chlorophyll a were negatively correlated with DMS,DMTS,and β-cyclocitral,whereas total phosphorus,total nitrogen,and ammonium （NH4＋-N） were positively correlated with DMS,DMTS,β-cyclocitral,and β-ionone.The experimental results suggested that preventing the anaerobic decomposition of cyanobacterial blooms is an important strategy against the recurrence of a malodor crisis in Lake Taihu.

Influence of sunlight on the proliferation of cyanobacterial blooms and its potential applications in Lake Taihu, China

To learn the relationship between sunlight intensity and cyanobacterial proliferations for the further control of the heavy blooms, enclosure experiment were conducted in Meiliang Bay, Lake Taihu by regulating the natural light intensities with different shading ratio （0% （full sunlight）, 10%, 25%, 50% and 75% of original natural sunlight intensities） from September to November in 2010. The results indicated that phytoplankton biomass （mean） decreased significantly when the shading ratios reached 50% or more. Higher shading ratios （e.g. 75%） were very efficient in controlling the average and total cyanobacterialbloom biomass, while 50% shading ratio was proven very effective either in controlling the peak value of phytoplankton biomass or postponing the occurrence of cyanobacterial blooms in Lake Talhu. In addition, phytoplankton composition and photosynthesis efficiency were also affected by altering the shading ratios, and in turn, they might also act on phytoplankton growth. Based on the results from the present study, intermediate shading strategies such as regulation of water level or turbidity through the hydrology regulations would probably be an effective and efficient method in controlling cyanobacterial blooms in large and shallow lakes.

Electrochemical inactivation of cyanobacteria and microcystin degradation using a boron-doped diamond anode-A potential tool for cyanobacterial bloom control

Cyanobacterial blooms are global phenomena that can occur in calm and nutrient-rich （eutrophic） fresh and marine waters. Human exposure to cyanobacteria and their biologically active products is possible during water sports and various water activities, or by ingestion of contaminated water. Although the vast majority of harmful cyanobacterial products are confined to the interior of the cells, these are eventually released into the surrounding water following natural or artificially induced cell death. Electrochemical oxidation has been used here to damage cyanobacteria to halt their proliferation, and for microcystin degradation under in-vitro conditions. Partially spent Jaworski growth medium with no addition of supporting electrolytes was used. Electrochemical treatment resulted in the cyanobacterial loss of cell-buoyancy regulation, cell proliferation arrest, and eventual cell death. Microcystin degradation was studied separately in two basic modes of treatment： batch-wise flow, and constant flow, for electrolytic-cell exposure. Batch-wise exposure simulates treatment under environmental conditions, while constant flow is more appropriate for the study of boron-doped diamond electrode efficacy under laboratory conditions. The effectiveness of microcystin degradation was established using high-performance liquid chromatography-photodiode array detector analysis, while the biological activities of the products were estimated using a colorimetric protein phosphatase-1 inhibition assay. The results indicate potential for the application of electro-oxidation methods for the control of bloom events by taking advantage of specific intrinsic ecological characteristics of bloom-forming cyanobacteria. The applicability of the use of boron-doped diamond electrodes in remediation of water exposed to cyanobacteria bloom events is discussed.

Simultaneous elimination of cyanotoxins and PCBs via mechanical collection of cyanobacterial blooms:An application of“green-bioadsorption concept”

In this study,the distribution,transfer and fate of both polychlorinated biphenyls（PCBs）and cyanotoxins via phytoplankton routes were systematically investigated in two Chinese lakes.Results indicated that PCB adsorption/bioaccumulation dynamics has significantly positive correlations with the biomass of green alga and diatoms.Total lipid content of phytoplankton is the major factor that influences PCB adsorption/bioaccumulation.Cyanobacterial blooms with relatively lower lipid content could also absorb high amount of PCBs due to their high cell density in the water columns,and this process was proposed as major route for the transfer of PCBs in Chinese eutrophic freshwater.According to these findings,a novel route on fates of PCBs via phytoplankton and a green bioadsorption concept were proposed and confirmed.In the practice of mechanical collections of bloom biomass from Lake Taihu,cyanotoxin/cyanobacteria and PCBs were found to be removed simultaneously very efficiently followed this theory.

Succession of Aphanizomenon flos-aquae and Microcystis aeruginosa in direct co-culture experiments at different temperatures and biomasses

Cyanobacterial blooms have become a serious global environmental issue due to their potential risk for releasing detrimental secondary metabolites into aquatic ecosystems,posing a great threat to water quality management for public health authorities.Aphanizomenon,a common filamentous cyanobacterial genus belonging to Nostocales,is under particular concern because its several members are able to form harmful blooms.Furthermore,succession of bloom between A.flos-aquae and Microcystis occurs in many natural lakes.To evaluate the competitiveness of A.flos-aquae vs.M.aeruginosa,two sets of experiments at different ratios of biomass at 15℃and 25℃were conducted.Results show that at 15℃,the two species were able to coexist,and A.flos-aquae showed a specific higher growth rate,and its growth was promoted by the presence of M.aeruginosa.At 25℃,the growth of A.flos-aquae was inhibited by the biomass of M.aeruginosa,and M.aeruginosa suppressed A.flos-aquae in competition.Additionally,the vegetative cell size of A.flos-aquae was significantly influenced by the co-culture with M.aeruginosa,whereas the filament length of A.flos-aquae was not significantly affected.This study confirms that temperature is the dominating factor on the succession of A.flos-aquae and M.aeruginosa of a different biomass.