Quantitative real-time PCR for determination of microcystin synthetase e copy numbers for microcystis and anabaena in lakes

Cyanobacterial mass occurrences in freshwater lakes are generally formed by Anabaena, Microcystis, and Planktothrix, which may produce cyclic heptapeptide hepatotoxins, microcystins. Thus far, identification of the most potent microcystin producer in a lake has not been possible due to a lack of quantitative methods. The aim of this study was to identify the microcystin-producing genera and to determine the copy numbers of microcystin synthetase gene E (mcyE) in Lake Tuusulanj?rvi and Lake Hiidenvesi in Finland by quantitative real-time PCR. The microcystin concentrations and cyanobacterial cell densities of these lakes were also determined. The microcystin concentrations correlated positively with the sum of Microcystis and Anabaena mcyE copy numbers from both Lake Tuusulanj?rvi and Lake Hiidenvesi, indicating that mcyE gene copy numbers can be used as surrogates for hepatotoxic Microcystis and ANABAENA: The main microcystin producer in Lake Tuusulanj?rvi was Microcystis spp., since average Microcystis mcyE copy numbers were >30 times more abundant than those of ANABAENA: Lake Hiidenvesi seemed to contain both nontoxic and toxic Anabaena as well as toxic Microcystis strains. Identifying the most potent microcystin producer in a lake could be valuable for designing lake restoration strategies, among other uses.     

Microcystin mcyA and mcyE Gene Abundances Are Not Appropriate Indicators of Microcystin Concentrations in Lakes

Cyanobacterial harmful algal blooms (cyanoHABs) are a primary source of water quality degradation in eutrophic lakes. The occurrence of cyanoHABs is ubiquitous and expected to increase with current climate and land use change scenarios. However, it is currently unknown what environmental parameters are important for indicating the presence of cyanoHAB toxins making them difficult to predict or even monitor on time-scales relevant to protecting public health. Using qPCR, we aimed to quantify genes within the microcystin operon (mcy) to determine which cyanobacterial taxa, and what percentage of the total cyanobacterial community, were responsible for microcystin production in four eutrophic lakes. We targeted Microcystis-16S, mcyA, and Microcystis, Planktothrix, and Anabaena-specific mcyE genes. We also measured microcystins and several biological, chemical, and physical parameters—such as temperature, lake stability, nutrients, pigments and cyanobacterial community composition (CCC)—to search for possible correlations to gene copy abundance and MC production. All four lakes contained Microcystis-mcyE genes and high percentages of toxic Microcystis, suggesting Microcystis was the dominant microcystin producer. However, all genes were highly variable temporally, and in few cases, correlated with increased temperature and nutrients as the summer progressed. Interestingly, toxin gene abundances (and biomass indicators) were anti-correlated with microcystin in all lakes except the largest lake, Lake Mendota. Similarly, gene abundance and microcystins differentially correlated to CCC in all lakes. Thus, we conclude that the presence of microcystin genes are not a useful tool for eliciting an ecological role for toxins in the environment, nor are microcystin genes (e.g. DNA) a good indicator of toxins in the environment.     

Detection of Microcystin-Producing Cyanobacteria in Finnish Lakes with Genus-Specific Microcystin Synthetase Gene E (mcyE) PCR and Associations with Environmental Factors

We studied the frequency and composition of potential microcystin (MC) producers in 70 Finnish lakes with general and genus-specific microcystin synthetase gene E (mcyE) PCR. Potential MC-producing Microcystis, Planktothrixand Anabaena spp. existed in 70%, 63%, and 37% of the lake samples, respectively. Approximately two-thirds of the lake samples contained one or two potential MC producers, while all three genera existed in 24% of the samples. In oligotrophic lakes, the occurrence of only one MC producer was most common. The combination of Microcystis and Planktothrix was slightly more prevalent than others in mesotrophic lakes, and the cooccurrence of all three MC producers was most widespread in both eutrophic and hypertrophic lakes. The proportion of the three-producer lakes increased with the trophic status of the lakes. In correlation analysis, the presence of multiple MC-producing genera was associated with higher cyanobacterial and phytoplankton biomass, pH, chlorophyll a, total nitrogen, and MC concentrations. Total nitrogen, pH, and the surface area of the lake predicted the occurrence probability of mcyE genes, whereas total phosphorus alone accounted for MC concentrations in the samples by logistic and linear regression analyses. In conclusion, the results suggested that eutrophication increased the cooccurrence of potentially MC-producing cyanobacterial genera, raising the risk of toxic-bloom formation.     

The dynamics of toxic Microcystis strains and microcystin production in two hypertrofic South African reservoirs

The South African impoundments of Hartbeespoort and Roodeplaat experience excessive blooms of Microcystis species each year. Microcystins, produced primarily by strains of cyanobacteria belonging to the genera Microcystis, Anabaena and Planktothrix, are harmful cyanobacterial hepatotoxins. These bloom-forming cyanobacteria form toxic and non-toxic strains that co-occur and are visually indistinguishable, but can be identified and quantified molecularly. We described the relationships between microcystin production and the genotypic composition of the Microcystis community involved together with environmental conditions in both the Roodeplaat and Hartbeespoort reservoirs using quantitative real time PCR. DNA copy number of the Microcystis-specific 16S rRNA and toxin biosynthesis genes, mcyE and mcyB, were measured. Planktothrix spp. occurred in both reservoirs during autumn, but no toxin-producing species was present as measured with mcyE specific primers, whereas both toxic and non-toxic strains of Microcystis were recorded in both reservoirs, with Microcystis spp. dominating in the summer months. Water-surface temperature correlated strongly with microcystin concentration, mcyE and mcyB copy number. Microcystin production was associated by temperatures higher than 23 °C. This suggests that should current environmental trends persist with surface water temperatures continuing to rise and more and more nutrients continued to be loaded into fresh water systems toxic Microcystis may outgrow non-toxic Microcystis and synthesise even more microcystins.     

Phylogenies of Microcystin-Producing Cyanobacteria in the Lower Laurentian Great Lakes Suggest Extensive Genetic Connectivity

Lake St. Clair is the smallest lake in the Laurentian Great Lakes system. MODIS satellite imagery suggests that high algal biomass events have occurred annually along the southern shore during late summer. In this study, we evaluated these events and tested the hypothesis that summer bloom material derived from Lake St. Clair may enter Lake Erie via the Detroit River and represent an overlooked source of potentially toxic Microcystis biomass to the western basin of Lake Erie. We conducted a seasonally and spatially resolved study carried out in the summer of 2013. Our goals were to: 1) track the development of the 2013 summer south-east shore bloom 2) conduct a spatial survey to characterize the extent of toxicity, taxonomic diversity of the total phytoplankton population and the phylogenetic diversity of potential MC-producing cyanobacteria (Microcystis, Planktothrix and Anabaena) during a high biomass event, and 3) compare the strains of potential MC-producers in Lake St. Clair with strains from Lake Erie and Lake Ontario. Our results demonstrated a clear predominance of cyanobacteria during a late August bloom event, primarily dominated by Microcystis, which we traced along the Lake St. Clair coastline downstream to the Detroit River''s outflow at Lake Erie. Microcystin levels exceeded the Province of Ontario Drinking Water Quality Standard (1.5 µg L⁻¹) for safe drinking water at most sites, reaching up to five times this level in some areas. Microcystis was the predominant microcystin producer, and all toxic Microcystis strains found in Lake St. Clair were genetically similar to toxic Microcystis strains found in lakes Erie and Ontario. These findings suggest extensive genetic connectivity among the three systems.     

Molecular Characterization of Potential Microcystin-Producing Cyanobacteria in Lake Ontario Embayments and Nearshore Waters

The distribution and genotypic variation of potential microcystin (MC) producers along the southern and eastern shores of Lake Ontario in 2001 and 2003 were examined using a suite of PCR primers. Cyanobacterial, Microcystis sp., and Microcystis-specific toxin primer sets identified shoreline distribution of cyanobacterial DNA (in 97% of the stations) and MC synthetase genes (in 50% of the stations). Sequence analysis of a partial mcyA amplicon targeting Microcystis, Anabaena, and Planktothrix species indicated that the Microcystis sp. genotype was the dominant MC genotype present and revealed a novel Microcystis-like sequence containing a 6-bp insert. Analysis of the same samples with genus-specific mcyE primers confirmed that the Microcystis sp. genotype was the dominant potential MC producer. Genotype compositions within embayments were relatively homogenous compared to those for shoreline and tributary samples. MC concentrations along the shoreline exhibited both temporal and spatial differences as evidenced by the protein phosphatase inhibition assay, at times exceeding the World Health Organization guideline value for drinking water of 1.0 μg MC-LR_eq liter⁻¹. MC genotypes are widespread along the New York State shoreline of Lake Ontario, appear to originate nearshore, and can be carried through the lake via wind and surface water current patterns.     

Ecological Dynamics of Toxic Microcystis spp. and Microcystin-Degrading Bacteria in Dianchi Lake,China

Toxic cyanobacterial blooms directly threaten both human safety and the ecosystem of surface waters. The widespread occurrence of these organisms, coupled with the tumor-promoting properties of the microcystin toxins that they produce, demands action to mitigate their potential impacts and, thus, a robust understanding of their ecological dynamics. In the present work, the abundance of toxic Microcystis spp. and microcystin (MC)-degrading bacteria in Dianchi Lake, located in Yunnan Province, China, was studied using quantitative PCR. Samples were taken at monthly intervals from June 2010 to December 2011 at three sampling stations within this freshwater lake. Results revealed that variation in the abundance of both total Microcystis spp. and toxic Microcystis spp. exhibited similar trends during the period of the algal bloom, including the reinvasion, pelagic growth, sedimentation, and overwintering periods, and that the proportion of toxic Microcystis was highest during the bloom and lowest in winter. Importantly, we observed that peaks in mlrA gene copy numbers of MC-degrading bacteria occurred in the months following observed peaks in MC concentrations. To understand this phenomenon, we added MCs to the MC-degrading bacteria (designated strains HW and SW in this study) and found that MCs significantly enhanced mlrA gene copy numbers over the number for the control by a factor of 5.2 for the microcystin-RR treatment and a factor of 3.7 for the microcystin-LR treatment. These results indicate that toxic Microcystis and MC-degrading bacteria exert both direct and indirect effects on each other and that MC-degrading bacteria also mediate a shift from toxic to nontoxic populations of Microcystis.     

The rise of potentially toxin producing cyanobacteria in Lake Naivasha,Great African Rift Valley,Kenya

Lake Naivasha, an important inland water ecosystem and a crucial freshwater resource in the Great African Rift Valley, has displayed clear signals of degradation in recent decades. We studied the phytoplankton composition and biomass levels in the period 2001–2013 and noted a progressive increase in the occurrence of potentially toxic cyanobacteria. Analyses for the presence of cyanotoxins such as microcystins (MC), cylindrospermopsin (CYN) and anatoxin-a (ATX-a) were carried out on samples collected in 2008–2013. Among the cyanotoxins tested, low concentrations of MC were detected in the lake. This is the first record of the occurrence of MC in Lake Naivasha. For the first time, molecular phylogenetic investigations of field clones of cyanobacteria from Lake Naivasha were carried out to establish the taxa of the dominant species. Amplification of the aminotrasferase (AMT) domain responsible for cyanotoxin production confirmed the presence of the mcyE gene belonging to the microcystin synthesis gene cluster in field samples containing Microcystis and Planktothrix species. These findings suggest that toxin producing cyanobacteria could become a threat to users of this over-exploited tropical lake in the near future.     

Cyanobacteria dynamics in a restored Finnish lake: a long term simulation study

Several explanations have been presented for the formation of lacustrine cyanobacteria blooms. These include elevated water temperature, nutrient enrichment, low N/P ratios, low light energy requirements, high pH and/or low carbon dioxide concentration, selective zooplankton grazing, excretion of compounds which suppress the growth of competing algae, and migration. The impact of the first four were studied in Lake Tuusulanjärvi, a eutrophic Finnish lake, using deterministic simulation. The study, which covered 15 years, included a sequence of cases on the recovery of the lake after the implementation of two restoration measures: aeration of the hypolimnion, and termination of municipal waste discharge, both of which were done during the study period. The focus was on Microcystis and Oscillatoria, and on the N-fixing cyanobacteria, Anabaena and Aphanizomenon. Eukaryotic phytoplankton were also included in the study. Monitoring data were used. The roles of the hypotheses were discussed, from the point of view of the utility of the information in water resources management.     

The effects of temperature and nutrients on the growth and dynamics of toxic and non-toxic strains of Microcystis during cyanobacteria blooms

In temperate latitudes, toxic cyanobacteria blooms often occur in eutrophied ecosystems during warm months. Many common bloom-forming cyanobacteria have toxic and non-toxic strains which co-occur and are visually indistinguishable but can be quantified molecularly. Toxic Microcystis cells possess a suite of microcystin synthesis genes (mcyA–mcyJ), while non-toxic strains do not. For this study, we assessed the temporal dynamics of toxic and non-toxic strains of Microcystis by quantifying the microcystin synthetase gene (mcyD) and the small subunit ribosomal RNA gene, 16S (an indicator of total Microcystis), from samples collected from four lakes across the Northeast US over a two-year period. Nutrient concentrations and water quality were measured and experiments were conducted which examined the effects of elevated levels of temperatures (+4 °C), nitrogen, and phosphorus on the growth rates of toxic and non-toxic strains of Microcystis. During the study, toxic Microcystis cells comprised between 12% and 100% of the total Microcystis population in Lake Ronkonkoma, NY, and between 0.01% and 6% in three other systems. In all lakes, molecular quantification of toxic (mcyD-possessing) Microcystis was a better predictor of in situ microcystin levels than total cyanobacteria, total Microcystis, chlorophyll a, or other factors, being significantly correlated with the toxin in every lake studied. Experimentally enhanced temperatures yielded significantly increased growth rates of toxic Microcystis in 83% of experiments conducted, but did so for non-toxic Microcystis in only 33% of experiments, suggesting that elevated temperatures yield more toxic Microcystis cells and/or cells with more mcyD copies per cell, with either scenario potentially yielding more toxic blooms. Furthermore, concurrent increases in temperature and P concentrations yielded the highest growth rates of toxic Microcystis cells in most experiments suggesting that future eutrophication and climatic warming may additively promote the growth of toxic, rather than non-toxic, populations of Microcystis, leading to blooms with higher microcystin content.     

Lake Erie Microcystis: Relationship between microcystin production, dynamics of genotypes and environmental parameters in a large lake

Cyanobacteria of genus Microcystis sp. have been commonly found in Lake Erie waters during recent summer seasons. In an effort to elucidate relationships between microcystin production, genotypic composition of Microcystis community and environmental parameters in a large lake ecosystem, we collected DNA samples and environmental data during a three-year (2003–2005) survey within Lake Erie and used the data to perform a series of correlation analyses. Cyanobacteria and Microcystis genotypes were quantified using quantitative real-time PCR (qPCR). Our data show that Microcystis in Lake Erie forms up to 42% of all cyanobacteria, and that Microcystis exists as a mixed population of potentially toxic and (primarily) non-toxic genotypes. In the entire lake, the total abundance of Microcystis as well as the abundance of microcystin-producing Microcystis is strongly correlated with the abundance of cyanobacteria suggesting that Microcystis is a significant component of the cyanobacterial community in Lake Erie during summer seasons. The proportion of total Microcystis of all cyanobacteria was strongly linked to the microcystin concentrations, while the percentage of microcystin-producing genotypes within Microcystis population showed no correlation with microcystin concentrations. Correlation analysis indicated that increasing total phosphorus concentrations correlate strongly with increasing microcystin concentrations as well as with the total abundance of Microcystis and microcystin-producing Microcystis.     

Dynamics and short-term survival of toxic cyanobacteria species in ballast water from NOBOB vessels transiting the Great Lakes—implications for HAB invasions

We measured the presence, viability and potential toxicity of cyanobacteria in ships’ ballast tanks during three domestic voyages through the North American Great Lakes. Using molecular methods, the toxin-producing forms of Microcystis and Anabaena were monitored in ballast water after ships’ ballast tanks were filled at their first port of call, and at subsequent ports as ships transited the Great Lakes. Microcystis was detected in ballast water at intermediate and final ports of call in all three experiments, but the presence of Anabaena was more variable, suggesting low abundance or patchy distribution in ballast tanks. Both species were detected in ballast water up to 11 days old. Detection of the microcystin synthetase gene, mcyE, in ballast tanks indicated entrained cells were capable of producing microcystin, and further analyses of RNA indicated the toxin was being expressed by Microcystis, even after 11 days in dark transit. These data demonstrate within-basin transport and delivery of planktonic harmful algal bloom (HAB) species to distant ports in the world's largest freshwater reservoir, with potential implications for drinking water quality. These implications are discussed with respect to management of microbial invasions and the fate of introduced phytoplankton in their receiving environment.     

Development and application of a multiplex qPCR technique to detect multiple microcystin-producing cyanobacterial genera in a Canadian freshwater lake

The emergence and persistence of complex blooms comprising multiple toxigenic cyanobacteria genera pose significant challenges for water quality management worldwide. The co-occurrence of morphologically indistinguishable toxic and non-toxic strains makes monitoring and control of these noxious organisms particularly challenging. Conventional monitoring approaches are not only incapable of discriminating toxic from non-toxic strains but also have proven to be less sensitive and specific. In this study, a multiplex quantitative real-time polymerase chain reaction (qPCR) approach was developed and tested for its sensitivity and specificity at detecting, differentiating and estimating potentially toxic Anabaena, Microcystis and Planktothrix genotype compositions in environmental samples. The oligonucleotide primers and probes utilized were designed to target portions of the microcystin synthetase (mcy) E gene that encode synthesis of the unique 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid (ADDA) moiety of microcystins in the three target genera. Laboratory evaluation showed the developed assay to be highly sensitive and specific at detecting and quantifying targeted genera. Indeed, the assay standards for the Anabaena, Microcystis and Planktothrix reactions attained efficiencies above 90 %, with coefficients of determination consistently above 0.99. Analysis of water samples from Missisquoi Bay, Quebec, Canada, resulted in successful detection and quantification of target toxigenic cyanobacteria even when cell numbers were below the detection limit for the conventional microscopy methods. Furthermore, toxigenic Microcystis spp. were found to be the main putative microcystin-producing cyanobacteria in the study lake. The qPCR technique developed in this study therefore offers simultaneous detection, differentiation and quantification of multiple toxigenic cyanobacteria that otherwise cannot be accomplished by current monitoring approaches.     

太湖水华期间有毒和无毒微囊藻种群丰度的动态变化

采用荧光定量PCR技术分析太湖3个湖区(梅梁湾、贡湖湾和湖心)水体中有毒和无毒微囊藻基因型丰度及有毒微囊藻比例的季节变化(2010年4-9月),并与环境因子进行统计分析。结果表明,有毒微囊藻基因型丰度及所占比例存在季节和空间差异:从4-8月,有毒微囊藻基因型丰度及其比例呈逐渐增加趋势,到9月开始下降;梅梁湾水体中有毒微囊藻基因型丰度及其比例高于贡湖湾和湖心。梅梁湾、贡湖湾和湖心有毒微囊藻在微囊藻种群中的比例变化范围分别为(26.2±0.8)%-(64.3±2.2)%、(4.4±0.2)%-(22.1±1.8)%和(10.4±0.4)%-(20.6±1.5)%。相关分析结果表明,有毒微囊藻丰度、总微囊藻丰度和叶绿素a浓度呈极显著正相关(P<0.01),均与温度呈显著正相关(P<0.05);有毒微囊藻比例与磷浓度呈显著正相关(P<0.05),与温度呈极显著正相关(P<0.01)。研究结果表明,温度和磷浓度是决定太湖有毒微囊藻种群丰度及其比例的关键因子。     

广东省水库微囊藻的产毒特征和ITS序列的遗传多样性分析

为了解广东省水库微囊藻的产毒特征和ITS 序列的遗传多样性,从广东省供水水库中分离得到28 株微囊藻(Microcystisspp.),对它们的产毒特征和15 株微囊藻的ITS 序列进行了分析.高效液相色谱(HPLC)和微囊藻毒素合成酶基因mcyE 的检测结果表明,广东省水库中的微囊藻以产毒藻株占优势,微囊藻毒素的主要类型为MC-RR.广东省15 株藻株的ITS 序列相似性大于93.2%,在用相邻法(NJ)构建的系统树上,不同形态的种和不同地理区域的藻株没有区分开,产毒和非产毒藻株没有形成独立分支.这说明微囊藻ITS 序列的遗传多样性较低,ITS 序列和mcyE 存在没有相关性,表型不能够反映藻株的进化关系.因此,有必要将藻类传统分类方法与分子方法结合起来对蓝藻进行重新分类.     

Molecular confirmation of Planktothrix rubescens as the cause of intense,microcystin—Synthesizing cyanobacterial bloom in Lake Ziros,Greece

Cyanobacterial blooms occur increasingly often and raise ecological concerns worldwide. In Mediterranean freshwater ecosystems algal blooms are commonly attributed to Microcystis, Anabaena, and Aphanizomenon genera while Planktothrix is the most common bloom forming cyanobacterium in deep Northern and prealpine European oligotrophic to mesotrophic lakes. In the framework of an undertaken study of cyanobacterial species in lakes of Northwestern Greece we investigated the cyanobacterial diversity in Lake Ziros throughout a 15-month period (January 2006–March 2007) by using molecular methods. Surprisingly, a severe cyanobacterial bloom occurred during the study period, which upon microscopic examination and detailed molecular characterization found to be caused by Planktothrix rubescens species. The appearance of P. rubescens from November 2006 coincided with poor cyanobacterial diversity and resulted in a thick epilimnetic bloom in March 2007 (3.1 × 10⁸ cells/l and microcystin concentration 199 μg/l). Genotype composition of the total cyanobacterial community of the lake was analyzed by using denaturing gradient gel electrophoresis (DGGE) profiling of the intergenic transcribed spacer region of the rnn operon (rRNA-ITS). A P. rubescens strain closely related to Kpr strain from Lake Klinckenberg, The Netherlands, was found to dominate. The importance of this observation is expanded by the fact that microcystin concentrations recorded in Lake Ziros were the highest measured ever in Greek aquatic ecosystems examined so far and also found amongst the highest recorded worldwide.     

Poor nutritional quality of primary producers and zooplankton driven by eutrophication is mitigated at upper trophic levels

Eutrophication and rising water temperature in freshwaters may increase the total production of a lake while simultaneously reducing the nutritional quality of food web components. We evaluated how cyanobacteria blooms, driven by agricultural eutrophication (in eutrophic Lake Köyliöjärvi) or global warming (in mesotrophic Lake Pyhäjärvi), influence the biomass and structure of phytoplankton, zooplankton, and fish communities. In terms of the nutritional value of food web components, we evaluated changes in the ω‐3 and ω‐6 polyunsaturated fatty acids (PUFA) of phytoplankton and consumers at different trophic levels. Meanwhile, the lakes did not differ in their biomasses of phytoplankton, zooplankton, and fish communities, lake trophic status greatly influenced the community structures. The eutrophic lake, with agricultural eutrophication, had cyanobacteria bloom throughout the summer months whereas cyanobacteria were abundant only occasionally in the mesotrophic lake, mainly in early summer. Phytoplankton community differences at genus level resulted in higher arachidonic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) content of seston in the mesotrophic than in the eutrophic lake. This was also reflected in the EPA and DHA content of herbivorous zooplankton (Daphnia and Bosmina) despite more efficient trophic retention of these biomolecules in a eutrophic lake than in the mesotrophic lake zooplankton. Planktivorous juvenile fish (perch and roach) in a eutrophic lake overcame the lower availability of DHA in their prey by more efficient trophic retention and biosynthesis from the precursors. However, the most efficient trophic retention of DHA was found with benthivorous perch which prey contained only a low amount of DHA. Long‐term cyanobacterial blooming decreased the nutritional quality of piscivorous perch; however, the difference was much less than previously anticipated. Our result shows that long‐term cyanobacteria blooming impacts the structure of plankton and fish communities and lowers the nutritional quality of seston and zooplankton, which, however, is mitigated at upper trophic levels.     

Analysis of environmental drivers influencing interspecific variations and associations among bloom-forming cyanobacteria in large,shallow eutrophic lakes

Non-diazotrophic Microcystis and filamentous N₂-fixing Aphanizomenon and Dolichospermum (formerly Anabaena) co-occur or successively dominate freshwaters globally. Previous studies indicate that dual nitrogen (N) and phosphorus (P) reduction is needed to control cyanobacterial blooms; however, N limitation may cause replacement of non-N₂-fixing by N₂-fixing taxa. To evaluate potentially counterproductive scenarios, the effects of temperature, nutrients, and zooplankton on the spatio-temporal variations of cyanobacteria were investigated in three large, shallow eutrophic lakes in China. The results illustrate that the community composition of cyanobacteria is primarily driven by physical factors and the zooplankton community, and their interactions. Niche differentiation between Microcystis and two N₂-fixing taxa in Lake Taihu and Lake Chaohu was observed, whereas small temperature fluctuations in Lake Dianchi supported co-dominance. Through structural equation modelling, predictor variables were aggregated into ‘composites’ representing their combined effects on species-specific biomass. The model results showed that Microcystis biomass was affected by water temperature and P concentrations across the studied lakes. The biomass of two filamentous taxa, by contrast, exhibited lake-specific responses. Understanding of driving forces of the succession and competition among bloom-forming cyanobacteria will help to guide lake restoration in the context of climate warming and N:P stoichiometry imbalances.