In eutrophic shallow lakes,cyanobacterial blooms will occur frequently and then settle into sediment,leading the formation of fluid sediment.Several factors including temperature can influence surface sediment propert...In eutrophic shallow lakes,cyanobacterial blooms will occur frequently and then settle into sediment,leading the formation of fluid sediment.Several factors including temperature can influence surface sediment properties.In this study,the influence of temperatures on surface sediment properties was determined in microcosm experiments through monitoring sediment physicochemical and rheological properties.During one-month incubation,it was found that surface sediment density and water content varied exponentially with increase in temperatures from 10 to 35℃.The results of particle size distribution indicated that cyanobacterial blooms biomass(CBB)degradation in sediment led to sediment flocculation and agglomeration.In themeantime,therewere high ratios polysaccharide/protein in extracellular polymeric substances(EPSs),which enhanced the sediment particle agglomeration.Further,the yield stress in rheological test for sediment with(R^(2)=0.97)and without(R^(2)=0.85)CBB presented an exponential decay with increase in temperatures.And a threshold value at 20℃ for sediment critical shear stress(τ_(cr))indicated that sediment could be resuspended easier when temperature was more than 20℃.Altogether,this study showed that the increase in temperatures with a threshold at 20℃,can cause sediment particle flocculation,resulting in a loose and fragile structure.And the results would be helpful to sediment management considering environmental effects of sediment suspension for eutrophication shallow lakes.展开更多
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 ob...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.展开更多
In aquatic ecosystems, macrophytes and phytoplankton are main primary producers, in which macrophyte plays an important role in maintaining clear water state, while phytoplankton often dominates in turbid waterbodies....In aquatic ecosystems, macrophytes and phytoplankton are main primary producers, in which macrophyte plays an important role in maintaining clear water state, while phytoplankton often dominates in turbid waterbodies. In the present study, the growth and photosynthetic activity of the submerged aquatic plant Ceratophyllum oryzetorum Kom. in different cell densities of cyanobacterial bloom are studied. The results show that the plant length and fresh mass of C. oryzetorum are promoted by low cyanobacterial cell densities. Medium and high cyanobacterial cell densities, on the contrary, act as inhibitory. Furthermore, the photosynthetic activity of C. oryzetorum is strongly inhibited by high cyanobacterial cell densities. To a certain extent, the growth of cyanobacteria is inhibited by C. oryzetorurn, but no significant effect is found in this study.展开更多
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 cha...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.展开更多
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 wi...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.展开更多
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 nat...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.展开更多
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 qualit...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.展开更多
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 m...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.展开更多
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 poll...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.展开更多
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...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.展开更多
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 wate...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.展开更多
We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population （M. aeruginosa） and their correlation with environmental factors in the water source area of Chaohu City, China ...We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population （M. aeruginosa） and their correlation with environmental factors in the water source area of Chaohu City, China from December 2011 to October 2012. The results show that species belonging to the phylum Cyanophyta occupied the maximum proportion of phytoplankton biomass, and that the dominant population in the water source area of Chaohu City was M. aeruginosa. The variation in cyanobacterial biomass from March to August 2012 was well fitted to the logistic growth model. The growth rate of cyanobacteria was the highest in June, and the biomass of cyanobacteria reached a maximum in August. From February to March 2012, the main form of M. aeruginosa was the single-cell form; M. aeruginosa colonies began to appear from April, and blooms appeared on the water surface in May. The maximum diameter of the colonies was recorded in July, and then gradually decreased from August. The diameter range ofM. aeruginosa colonies was 18.37-237.77μm, and most of the colonies were distributed in the range 20-200μm, comprising 95.5% of the total number of samples. Temperature and photosynthetically active radiation may be the most important factors that influenced the annual variation in M. aeruginosa biomass and forms. The suitable temperature for cyanobaeterial growth was in the range of 15-30℃. In natural water bodies, photosynthetically active radiation had a significant positive influence on the colonial diameter of M. aeruginosa （P〈0.01）.展开更多
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 o...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.展开更多
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 ...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.展开更多
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 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.展开更多
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...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.展开更多
The effects of a cyanobacterial extract （CE） on Helicobacter pylori biofilm formation onto hydrophobic and hydrophilic abiotic surfaces and the expression of luxS, flaA, omp18, lpxD and ureA genes associated to biof...The effects of a cyanobacterial extract （CE） on Helicobacter pylori biofilm formation onto hydrophobic and hydrophilic abiotic surfaces and the expression of luxS, flaA, omp18, lpxD and ureA genes associated to biofilm were studied. NCTC11638 reference strain and HP796, a resistant clinical isolate, were grown in Mueller-Hinton broth supplemented with 5% fetal calf serum （FCS） or 1% CE. The ability to form biofilm, viability, morphological changes and gene expression of adhered H. pylori cells were determined. The strains were able to form biofilm on both surfaces with the nutritional supplements analyzed. H. pylori conserved a characteristic bacillary morphology and viability with CE. Cells attachment was higher with CE than FCS regardless of strains and surfaces. The most remarkable increase in gene expression was observed with the ompl8 gene using the CE supplement, indicating the important participation of outer membrane proteins in biofilm establishment. The clinical isolate showed similar and even greater gene expression than the reference strain. The results obtained indicated that the nutrients provided by CE favored biofilm formation with retained pathogenicity that under certain conditions can occur in natural aquatic environments.展开更多
Lake Erhai,a lake in the early stage of eutrophication,has been threatened by algal blooms(particularly the overproliferation of blue-green algae),which can have an impact on drinking water safety and the lake's e...Lake Erhai,a lake in the early stage of eutrophication,has been threatened by algal blooms(particularly the overproliferation of blue-green algae),which can have an impact on drinking water safety and the lake's ecosystem.Understanding the governing factors of cyanobacterial blooms is critical for taking timely and effective action during this key eutrophication-transition period.However,long-term records of cyanobacterial bloom and its key dominating factors remain unclear.It is,therefore,essential to understand the bloom dynamics and the driving forces before any control strategies can be determined.We investigated the cyanobacterial phycocyanin concentration variability based on satellite observations from 2003 to 2019,by using the empirical orthogonal function analysis.We observed a decrease in the coverage of the dominant mode of variability in phycocyanin magnitudes compared to the period 2003 to 2011,with variations primarily occurring in the northern bays.The largest variability was identified to be predominant in July,and an apparent timing shift in variability was observed in December 2016 and 2017.The 95%quantile regression model indicated a distinct upper boundary response in cyanobacteria proliferation to the joint Total Nitrogen(TN)and Total Phosphorus(TP)concentrations,which occurred in summer from 2003 to 2011.An apparent response of cyanobacterial bloom to TP was observed during the winters from 2016 to 2019.Additionally,water level and TN:TP ratio played a central role in summer from 2003 to 2011,while from 2016 to 2019,TN:TP ratio was found to dominate in the summer months.In winter,air temperature turned out to be a significant modulating factor compared to water level.Our results suggest that implementing a phosphorus reduction strategy,while controlling TN:TP ratio and suitable water level manipulation,should be considered to ensure the sustainability of Lake Erhai,especially under a consistent global warming scenario.展开更多
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 adsor...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.展开更多
Cyanobacteria blooms and their secondary hazards(cyanotoxins,taste and odor compounds)continue to harm the ecological environment of natural and semi-artificially regulated water bodies in the world,thus affecting the...Cyanobacteria blooms and their secondary hazards(cyanotoxins,taste and odor compounds)continue to harm the ecological environment of natural and semi-artificially regulated water bodies in the world,thus affecting the safety of water supply and aquatic product quality.The 8 th National Cyanobacteria Bloom Forum was successfully held on July 14-16,2023,in Tianjin,China.The forum established an academic exchange platform for nearly 300 water ecology experts,reservoir managers,and aquaculture technicians.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52209102 and U2240208)the Doctoral Program of Entrepreneurship and Innovation in Jiangsu Province(No.JSSCBS20211393)+1 种基金the Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.YJKYYQ20190050)the Science and Technology Innovation Project of Jiang Province,China(No.BK20220043).
文摘In eutrophic shallow lakes,cyanobacterial blooms will occur frequently and then settle into sediment,leading the formation of fluid sediment.Several factors including temperature can influence surface sediment properties.In this study,the influence of temperatures on surface sediment properties was determined in microcosm experiments through monitoring sediment physicochemical and rheological properties.During one-month incubation,it was found that surface sediment density and water content varied exponentially with increase in temperatures from 10 to 35℃.The results of particle size distribution indicated that cyanobacterial blooms biomass(CBB)degradation in sediment led to sediment flocculation and agglomeration.In themeantime,therewere high ratios polysaccharide/protein in extracellular polymeric substances(EPSs),which enhanced the sediment particle agglomeration.Further,the yield stress in rheological test for sediment with(R^(2)=0.97)and without(R^(2)=0.85)CBB presented an exponential decay with increase in temperatures.And a threshold value at 20℃ for sediment critical shear stress(τ_(cr))indicated that sediment could be resuspended easier when temperature was more than 20℃.Altogether,this study showed that the increase in temperatures with a threshold at 20℃,can cause sediment particle flocculation,resulting in a loose and fragile structure.And the results would be helpful to sediment management considering environmental effects of sediment suspension for eutrophication shallow lakes.
基金supported by the National Natural Science Foundation of China (Nos. 41230744, 51279194, 41271355, 41325001)
文摘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.
基金Supported by the Innovation Project of CAS (No.KZCX2-YW-426)a Provincial Project of Hubei (No. 2006AA305A0402)the National Basic Research Program of China (973 Program, No. 2002CB 412306)
文摘In aquatic ecosystems, macrophytes and phytoplankton are main primary producers, in which macrophyte plays an important role in maintaining clear water state, while phytoplankton often dominates in turbid waterbodies. In the present study, the growth and photosynthetic activity of the submerged aquatic plant Ceratophyllum oryzetorum Kom. in different cell densities of cyanobacterial bloom are studied. The results show that the plant length and fresh mass of C. oryzetorum are promoted by low cyanobacterial cell densities. Medium and high cyanobacterial cell densities, on the contrary, act as inhibitory. Furthermore, the photosynthetic activity of C. oryzetorum is strongly inhibited by high cyanobacterial cell densities. To a certain extent, the growth of cyanobacteria is inhibited by C. oryzetorurn, but no significant effect is found in this study.
基金supported by the National Basic Research Program (973) of China (No. 2008CB418101)the State Key Laboratory of Freshwater Ecology and Biotechnology (No. 2008FBZ01)
文摘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.
基金Supported by the National Key R&D Program of China(No.2018YFE0103700)the National Natural Science Foundation(Nos.41876124,61871293,42007372)the Zhejiang Provincial Natural Science Foundation of China(Nos.LZ21C030001,LD21C030001,LQ20C030008)。
文摘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.
基金supported by the National Major Science and Technology Program for Water Pollution Control and Treatment(No.2009ZX07101-013)the National High Technology Research and Development Program(863)of China(No.2009AA063005)
文摘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.
基金supported by the National Water Pollution Control and Management Technology Major Project(No.2012ZX07101-010)the State Key Laboratory of Freshwater Ecology and Biotechnology(No.2011FBZ07)
文摘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.
基金Supported by the National Science Foundation of China(Nos.32071573,41877544)the Science and Technology Service Network Initiative of Chinese Academy of Sciences(No.KFJ-STS-QYZD-2021-01-002)the Science and Technology Achievement Transformation Foundation of Inner Mongolia Autonomous Region(No.2021CG0013)。
文摘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.
文摘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.
文摘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.
基金supported by the Slovenian Research Agency(Research Programme P1-0245ARRS:Ecotoxicology,Toxicogenomics and Carcinogenesis)Research Project L1-5456(Control of harmful cyanobacterial bloom in freshwater bodies),with co-funding from the Ministry of Defence,Administration for Civil Protection and Disaster Relief(Contract No URSZR 4300-1117/2009-1)the framework of the Life+Project(LIFE12ENV/SI/783 LIFE Stop Cyanobloom)
文摘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.
基金Supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China(Nos.2012ZX07103-005-01,2012ZX07103-004-02)the National Natural Science Foundation of China(Nos.41171366,41471075)the Science Foundation of Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences(No.NIGLAS2012135013)
文摘We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population （M. aeruginosa） and their correlation with environmental factors in the water source area of Chaohu City, China from December 2011 to October 2012. The results show that species belonging to the phylum Cyanophyta occupied the maximum proportion of phytoplankton biomass, and that the dominant population in the water source area of Chaohu City was M. aeruginosa. The variation in cyanobacterial biomass from March to August 2012 was well fitted to the logistic growth model. The growth rate of cyanobacteria was the highest in June, and the biomass of cyanobacteria reached a maximum in August. From February to March 2012, the main form of M. aeruginosa was the single-cell form; M. aeruginosa colonies began to appear from April, and blooms appeared on the water surface in May. The maximum diameter of the colonies was recorded in July, and then gradually decreased from August. The diameter range ofM. aeruginosa colonies was 18.37-237.77μm, and most of the colonies were distributed in the range 20-200μm, comprising 95.5% of the total number of samples. Temperature and photosynthetically active radiation may be the most important factors that influenced the annual variation in M. aeruginosa biomass and forms. The suitable temperature for cyanobaeterial growth was in the range of 15-30℃. In natural water bodies, photosynthetically active radiation had a significant positive influence on the colonial diameter of M. aeruginosa （P〈0.01）.
基金This study was supported by the National Natural Science Foundation of China(U2003014,41977099,419901134)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA2005020402)+1 种基金the 13th Fiveyear Informatization Plan of the Chinese Academy of Sciences(XXH13503-03-106)the China Biodiversity Observation Networks(Sino BON).
文摘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.
基金supported by the National Natural Science Foundation of China(Grant No.11672177).
文摘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.
基金Project supported by the National Natural Science Foundation of China(Grant No.11672177).
文摘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.
基金Supported by the National Major Science and Technology Program for Water Pollution Control and Treatment(2012ZX07103-003 and 2012ZX07103-004)
文摘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.
文摘The effects of a cyanobacterial extract （CE） on Helicobacter pylori biofilm formation onto hydrophobic and hydrophilic abiotic surfaces and the expression of luxS, flaA, omp18, lpxD and ureA genes associated to biofilm were studied. NCTC11638 reference strain and HP796, a resistant clinical isolate, were grown in Mueller-Hinton broth supplemented with 5% fetal calf serum （FCS） or 1% CE. The ability to form biofilm, viability, morphological changes and gene expression of adhered H. pylori cells were determined. The strains were able to form biofilm on both surfaces with the nutritional supplements analyzed. H. pylori conserved a characteristic bacillary morphology and viability with CE. Cells attachment was higher with CE than FCS regardless of strains and surfaces. The most remarkable increase in gene expression was observed with the ompl8 gene using the CE supplement, indicating the important participation of outer membrane proteins in biofilm establishment. The clinical isolate showed similar and even greater gene expression than the reference strain. The results obtained indicated that the nutrients provided by CE favored biofilm formation with retained pathogenicity that under certain conditions can occur in natural aquatic environments.
基金supported by the National Natural Science Foundation of China[grant number 41971402]the Central Fund Supporting Nonprofit Scientific Institutes for Basic Research and Development[grant number PM-zx703-202104-051]+2 种基金the Science and Technology Project of Department of Natural Resources of Hubei Province[grant number ZRZY2023KJ41]the Science and Technology Program of Guangzhou,China[grant number 202102080268]the ESA-MOST Dragon Program,and the LIESMARS Special Research Funding.
文摘Lake Erhai,a lake in the early stage of eutrophication,has been threatened by algal blooms(particularly the overproliferation of blue-green algae),which can have an impact on drinking water safety and the lake's ecosystem.Understanding the governing factors of cyanobacterial blooms is critical for taking timely and effective action during this key eutrophication-transition period.However,long-term records of cyanobacterial bloom and its key dominating factors remain unclear.It is,therefore,essential to understand the bloom dynamics and the driving forces before any control strategies can be determined.We investigated the cyanobacterial phycocyanin concentration variability based on satellite observations from 2003 to 2019,by using the empirical orthogonal function analysis.We observed a decrease in the coverage of the dominant mode of variability in phycocyanin magnitudes compared to the period 2003 to 2011,with variations primarily occurring in the northern bays.The largest variability was identified to be predominant in July,and an apparent timing shift in variability was observed in December 2016 and 2017.The 95%quantile regression model indicated a distinct upper boundary response in cyanobacteria proliferation to the joint Total Nitrogen(TN)and Total Phosphorus(TP)concentrations,which occurred in summer from 2003 to 2011.An apparent response of cyanobacterial bloom to TP was observed during the winters from 2016 to 2019.Additionally,water level and TN:TP ratio played a central role in summer from 2003 to 2011,while from 2016 to 2019,TN:TP ratio was found to dominate in the summer months.In winter,air temperature turned out to be a significant modulating factor compared to water level.Our results suggest that implementing a phosphorus reduction strategy,while controlling TN:TP ratio and suitable water level manipulation,should be considered to ensure the sustainability of Lake Erhai,especially under a consistent global warming scenario.
基金supported by the National Natural Science Foundation of China(Nos.41276150,51679169 and 40971249)
文摘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.
基金Supported by the National Natural Science Foundation of China(Nos.32172978,31772857)the Natural Science Foundation of Tianjin(No.22JCYBJC00430)。
文摘Cyanobacteria blooms and their secondary hazards(cyanotoxins,taste and odor compounds)continue to harm the ecological environment of natural and semi-artificially regulated water bodies in the world,thus affecting the safety of water supply and aquatic product quality.The 8 th National Cyanobacteria Bloom Forum was successfully held on July 14-16,2023,in Tianjin,China.The forum established an academic exchange platform for nearly 300 water ecology experts,reservoir managers,and aquaculture technicians.
