NOAA Center for Excellence for Great Lakes and Human Health Center Library - Harmful Algal Bloom Research Articles Archive

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Harmful Algal Bloom Research Articles Archive

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2007

Algal and cyanobacterial secondary metabolites in freshwaters: a comparison of allelopathic compounds and toxins
Authors: Leflaive, Jose’Phine; Ten-Hage, Loïc
Source: Freshwater Biology, February 2007, 52(2): 199-214(16)

Abstract:
1. The photoautotrophic micro-organisms collectively termed `micro-algae' (including micro-eukaryotes and cyanobacteria) are known to produce a wide range of secondary metabolites with various biological actions. A small subset of these compounds has been identified. Some of them, termed allelopathic compounds, have been shown to play a role in allelopathy, defined here as inhibitory effects of secondary metabolites against either competitors or predators. Freshwater cyanobacteria also produce some secondary metabolites, termed toxins, which are highly toxic for animals.
2. While allelopathic compounds play a role in the interactions between the emitter organisms and their direct competitors or predators, toxins are categorised according to their toxic effect on several organisms, including some that may not be present in their immediate environment. However, these two definitions are not mutually exclusive. This review considers the evolutionary, ecological and physiological aspects of the production of allelopathic compounds by micro-algae in freshwaters, and compares the characteristics of allelopathic compounds with those of toxins.
3. Allelopathic compounds include alkaloids, cyclic peptides, terpens and volatile organic compounds. Toxins include alkaloids, cyclic peptides and lipopolysaccharides. No allelopathic compound type is associated with a particular phylogenetic group of algae. In contrast, freshwater toxins are only produced by cyanobacteria belonging to a restricted number of genera. Allelopathic compounds have various modes of action, from inhibition of photosynthesis to oxidative stress or cellular paralysis. Toxins are often enzyme inhibitors, or interfere with cell membrane receptors.
4. The ecological roles of allelopathic compounds have been well identified in several cases, but those of toxins are still debated. In the light of descriptions of negative effects of toxins on both micro-invertebrates and photoautotrophic organisms, we suggest that at least some toxins should actually be considered as allelopathic compounds. Further research on toxic secondary metabolites in freshwaters is now needed, with emphasis on the ecological effects of the compounds in the immediate environment of the emitter algae.

Anatomy of the Recurrent Coastal Sediment Plume in Lake Michigan and its Impacts on Light Climate, Nutrients, and Plankton
Authors: H. A. Vanderploeg, J. R. Liebig, B. J. Eadie, J. F. Cavaletto, T. H. Johengen, G. S. Miller, S. A. Ruberg, M. J. McCormick, P. J. Lavrentyev,C. Chen, G. A. Lang, M. A. Agy, M. H. Bundy
Affiliations: Great Lakes Environmental Research Laboratory, National Oceanic and Atmospheric Administration, Ann Arbor, Michigan, USA, Cooperative Institute for Limnology and Ecosystem Research, Ann Arbor, Michigan, USA, Department of Biology, University of Akron, Akron, Ohio, USA, School of Marine Science and Technology, University of Massachusetts–Dartmouth, Dartmouth, Massachusetts, USA, School of Natural Resources and the Environment, University of Michigan, Ann Arbor, Michigan, USA, Office of Polar Programs, National Science Foundation, Arlington, Virginia, USA
Source: Journal of Geophysical Research, March 6, 2007, 112

Abstract: As part of the Episodic Events Great Lakes Experiment, we sampled total suspended matter (TSM), light climate, nutrients, and plankton along cross-margin transects in southern Lake Michigan during February, March, and April 1998–2000 to capture conditions before, during, and after the occurrence of storm-driven recurrent coastal sediment plumes to define the anatomy of the resuspension events and get insights into their interactions with nutrients and plankton. Variability in timing and strength of winter storms among years led to different timing, intensity, and extent of plumes among years. TSM concentrations in the core of plumes varied between 15 and 30 mg L–1, and photic depth was reduced to 1 to 2 m, thus potentially seriously limiting phytoplankton growth in plume areas. Total P concentration was highly correlated with TSM and river influence. Chlorophyll concentrations were lower in plume regions than in adjacent areas, in contrast to the relatively constant chlorophyll concentration across the plume predicted by a coupled hydrodynamic and nutrient-phytoplankton-zooplankton model. Contrary to expectation, protozoan microzooplankton (MZ) biomass was not more abundant in the plume than adjacent waters, but was highest in nearshore areas receiving river inflow. Storms affected horizontal distribution of zooplankton. Because of the lower concentrations of phytoplankton in the plume, the plume over the short term had a negative impact on zooplankton during this food-limiting season. Our results combined with those of other EEGLE studies lead us to conclude that storms and storm-driven plumes had a negative effect on the planktonic food web.

Antioxidant Enzyme Activities of Microcystis Aeruginosa in Response to Nonylphenols and Degradation of Nonylphenols by M. Aeruginosa
Authors: Wang J, Xie P.
Affiliations: Donghu Experimental Station of the Lake Ecosystems, The State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, P. R. China
Source: Environment Geochemical Health, March 7, 2007

Abstract: The aim of this study was to examine the effects of chemical nonylphenols (NPs) on the antioxidant system of Microcystis aeruginosa strains. The degradation and sorption of NPs by M. aeruginosa were also evaluated. High concentrations of NPs (1 and 2 mg/l) were found to cause increases in superoxidase dismutase (SOD) and glutathione-S-transferase (GST) activities and in glutathione (GSH) levels. These results suggest that toxic stress manifested by elevated SOD and GST levels and GSH contents may be responsible for the toxicity of NPs to M. aeruginosa and that the algal cells could improve their antioxidant and detoxification ability through the enhancement of enzymatic and nonenzymatic prevention substances. The observed elevations in GSH levels and GST activities were relatively higher than those in SOD activities, indicating that GSH and GST contributed more in eliminating toxic effects than SOD. Low concentrations of NPs (0.05-0.2 mg/l) enhanced cell growth and decreased GST activity in algal cells of M. aeruginosa, suggesting that NPs may have acted as a protecting factor, such as an antioxidant. The larger portion of the NPs (›60%) disappeared after 12 days of incubation, indicating the strong ability of M. aeruginosa to degrade the moderate persistent NP compounds. The sorption ratio of M. aeruginosa after a 12-day exposure to low nominal concentrations of NPs (0.02-0.5 mg/l) was relatively high (›30%). The fact that M. aeruginosa effectively resisted the toxic effects of NPs and strongly degraded these pollutants indicate that M. aeruginosa cells have a strong ability to adapt to variations in environmental conditions and that low and moderate concentrations of organic compounds may favor its survival. Further studies are needed to provide detailed information on the fate of persistent organic pollutants and the survival of algae and to determine the possible role of organic pollutants in the occurrence of water blooms in eutrophic lakes.

Biochemical, Morphological, and Genetic Variations in Microcystis Aeruginosa Due to Colony Disaggregation
Authors: Min Zhang^{1, 2}, Fanxiang Kong¹, Xiao Tan^{1, 2}, Zhou Yang^{1, 2, 3}, Huansheng Cao^{1, 2} and Peng Xing1²
Affiliations: Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, People’s Republic of China, Graduate School of Chinese Academy of Sciences, Beijing, 100039, People’s Republic of China, School of Biological Sciences, Nanjing Normal University, Nanjing, 210097, People’s Republic of China
Source: World Journal of Microbiology and Biotechnology, 22 March 2007, 23(5):663-670

Abstract: Microcystis aeruginosa commonly occurs as large colonial morph under natural conditions, but disaggregates and exists as single cells in laboratory cultures. To demonstrate the adaptive changes, differentiation of carbohydrates, pigments, and protein between colonial and disaggregated M. aeruginosa were examined. Their morphological and ultrastructural characteristics were subsequently observed by scanning electron microscopy and transmission electron microscopy. Results showed that chlorophyll a and phycocyanin in cells, soluble carbohydrate produced in the culture medium, and total carbohydrate in cells and sheath of colonial M. aeruginosa are significantly higher (p ‹ 0.05) compared with those in disaggregated cells. No significant change was found in protein concentration per cell (p › 0.05) between them. Their morphological and ultrastructural characteristics were evidently different, and by morphological criteria they could be separated into two morphotypes. In addition, the genetic diversity of 16S–23S internal transcribed spacer of them were examined and compared with reference strains of M. aeruginosa. The alignment of two sequences revealed that genetic identity level was extremely high (96.94%) and no significant difference was found in the nucleotide diversity (0.014 ± 0.008). This suggested that similar genotypes could present distinct morphotypes in M. aeruginosa. The tree topologies and analysis of molecular variance of the two sequences and reference sequences from GenBank database indicated that the genotypes of M. aeruginosa strains were not always related to their localities and exhibit heterogeneity within a species.

Buoyancy Regulation Of Microcystis Flos-Aquae During Phosphorus-Limited And Nitrogen-Limited Growth
Authors: Zhaosheng Chu* and Xiangcan Jin, Bo Yang and Qingru Zeng
Affiliations: State environmental protection key laboratory for lake pollution control/Research Center for Lake Ecology & Environments, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, China, 100012, Department of environmental technology, Hunan agricultural University, Hunan, China, 410128
Source: Journal of Plankton Research, 7 June 2007, fbm054

Abstract: The dominance of gas-vacuolate cyanobacteria is often attributed to their buoyancy and to their ability to regulate buoyancy in response to environmental conditions. Changes in absolute gas vesicles volume, carbohydrate content, protein content, and colony buoyancy of Microcystis flos-aquae were investigated during nitrogen-limited, phosphorus-limited and nutrient-replete growth. When nutrient-replete, M. flos-aquae cells consistently had excess gas vesicles, which provided sufficient buoyancy that the influence of daily carbohydrate changes on cells upon floataton was negligible. However, during nitrogen-limited growth, gas vesicle volume per cell decreased significantly with nitrogen exhaustion. The maximum decrease of gas vesicle volume was up to 84–88 %. At the same time, cellular carbohydrate content had an accumulation trend. The decrease of gas vesicle buoyancy together with the daily increase in carbohydrate are suggested to explain the daily changes in the cell floatation. During phosphorus-limited growth, gas vesicle volume per cell decreased slightly (maximum to 22–32 %), and they still provided sufficient buoyancy that most cells kept floating even though there were significant daily carbohydrate changes. Since nitrogen limitation caused more significant buoyancy loss than phosphorus limitation did, surface water blooms may disappear or appear frequently in nitrogen limited water bodies while they may persist a longer time in phosphorus limited water bodies. The quantitative analysis in buoyancy change by gas vesicles, carbohydrate and protein suggested that long-term buoyancy regulation was mainly determined by changes of gas vesicle volume whereas short-termbuoyancy regulation was mainly determined by carbohydrate accumulation and consumption. Both long-term and short-term buoyancy regulation were influenced by cell nutrient status. Furthermore, gas vesicle volume per cell and protein content changed in the same way in both nitrogen-limited and phosphorus-limited growth, which implied that the decrease of gas vesicles were associated with controls of total protein synthesis.

Cellular Proteins of Microcystis Aeruginosa Inhibiting Coagulation with Polyaluminum Chloride
Authors: Takaara T, Sano D, Konno H, Omura T.
Affiliation: Department of Civil Engineering, Graduate School of Engineering, Tohoku University, Aoba 6-6-06, Sendai 980-8579, Japan.
Source: Water Resource, 13 March 2007, 41(8):1653-8

Abstract: Cyanobacterial growth in semi-closed water areas such as reservoirs brings about a coagulation inhibition in a drinking water treatment system, but the inhibitory substances and mechanisms involved have yet to be elucidated. In this study, proteins having a high affinity with polyaluminum chloride (PACl) were isolated from organic substances produced by Microcystis aeruginosa with the affinity chromatography technique. Both extracellular organic matter (EOM) and cellular organic matter (COM) disturbed the flocculation of suspended kaolin with PACl, but it was likely that nonproteinous substances in EOM cause the reduction of coagulation effciency. In contrast, proteins in COM were obtained as possible inhibitory substances for the coagulation with PACl. These proteins could consume PACl in the coagulation process due to the formation of chelate complexes between these inhibitory proteins and the coagulant. The consumption of PACl by cyanobacterial proteins could be one of the important causes of the increase in coagulant demand.

Competition for Light Between Toxic and Nontoxic Strains of the Harmful Cyanobacterium Microcystis
Authors: Kardinaal WE, Tonk L, Janse I, Hol S, Slot P, Huisman J, Visser PM.
Affiliations: Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Nieuwe Achtergracht 127, 1018 WS Amsterdam, The Netherlands.
Source: Applied Environmental Microbiology, May 2007, 73(9): 2939-46

Abstract: The cyanobacterium Microcystis can produce microcystins, a family of toxins that are of major concern in water management. In several lakes, the average microcystin content per cell gradually declines from high levels at the onset of Microcystis blooms to low levels at the height of the bloom. Such seasonal dynamics might result from a succession of toxic to nontoxic strains. To investigate this hypothesis, we ran competition experiments with two toxic and two nontoxic Microcystis strains using light-limited chemostats. The population dynamics of these closely related strains were monitored by means of characteristic changes in light absorbance spectra and by PCR amplification of the rRNA internal transcribed spacer region in combination with denaturing gradient gel electrophoresis, which allowed identification and semiquantification of the competing strains. In all experiments, the toxic strains lost competition for light from nontoxic strains. As a consequence, the total microcystin concentrations in the competition experiments gradually declined. We did not find evidence for allelopathic interactions, as nontoxic strains became dominant even when toxic strains were given a major initial advantage. These findings show that, in our experiments, nontoxic strains of Microcystis were better competitors for light than toxic strains. The generality of this finding deserves further investigation with other Microcystis strains. The competitive replacement of toxic by nontoxic strains offers a plausible explanation for the gradual decrease in average toxicity per cell during the development of dense Microcystis blooms.

Design and Implementation of a Distributed GIS Portal for Oil Spill and Harmful Algal Bloom Monitoring in the Marine Environment
Authors: Éamonn Ó Tuama^a; Torill Hamre^b
Affiliaitons:^aCoastal & Marine Resources Centre, ERI, University College Cork. Ireland ^bNansen Environmental and Remote Sensing Center. Bergen. Norway
Source: Marine Geodesy, January 2007, 30(1-2): 145 - 168

Abstract: A web-based distributed system for monitoring and forecasting of the marine environment has been developed in line with INfrastructure for SPatial InfoRmation in Europe (INSPIRE) and Global Monitoring for Environment and Security (GMES) recommendations for a European Spatial Data Infrastructure (SDI). This system, called DISPRO, enables integration and distribution of multi-source data from satellites, aircraft, and in situ instruments, as well as results from numerical models. Geographic data and metadata are stored on a set of distributed computer nodes and retrieved and integrated by a web GIS client by means of Open Geospatial Consortium (OGC) Web Map Server (WMS) technologies. A profile of ISO 19115 was developed for metadata handling, using eXtensible Markup Language (XML) as a platform independent encoding mechanism. DISPRO has been demonstrated in six European coastal zone and ocean regions in the spring and summer of 2005. The overall positive experiences of both service providers and end users indicate that the system should be further developed into an operational GMES service.

Detection of Bacteria Associated with Harmful Algal Blooms from Coastal and Microcosm Environments Using Electronic Microarrays
Authors: Edward A. Barlaan, Seiji Furukawa, Kazuhisa Takeuchi (2007)
Afilliations: Nagasaki Industrial Promotion Foundation, Ikeda 2-1303-8, Omura City Nagasaki 856-0026, Japan, Seiji Furukawa22Mitsubishi Heavy Industries, Ltd, Nagasaki Research and Development Center, Fukahori-machi 5-717-1, Nagasaki 851-0392, Japan. and Kazuhisa Takeuchi22Mitsubishi Heavy Industries, Ltd, Nagasaki Research and Development Center, Fukahori-machi 5-717-1, Nagasaki 851-0392, Japan, Mitsubishi Heavy Industries, Ltd, Nagasaki Research and Development Center, Fukahori-machi 5-717-1, Nagasaki 851-0392, Japan.
Source: Environmental Microbiology March 2007, 9(3): 690–702

Abstract: With the global expansion of harmful algal blooms (HABs), several measures, including molecular approaches, have been undertaken to monitor its occurrence. Many reports have indicated the significant roles of bacteria in controlling algal bloom dynamics. Attempts have been made to utilize the bacteria/harmful algae relationship in HAB monitoring. In this study, bacterial assemblages monitored during coastal HABs and bacterial communities in induced microcosm blooms were investigated. Samples were analysed using denaturing gradient gel electrophoresis (DGGE) of the 16S rRNA gene. DGGE bands with peculiar patterns before, during, and after algal blooms were isolated and identified. Probes for six ribotypes representing organisms associated with Chatonella spp., Heterocapsa circularisquama, or Heterosigma akashiwo were used for analysis on NanoChip electronic microarray. In addition, a new approach using cultured bacteria species was developed to detect longer (533 bp) polymerase chain reaction-amplified products on the electronic microarray. The use of fluorescently labelled primers allowed the detection of individual species in single or mixed DNA conditions. The developed approach enabled the detection of the presence or absence and relative abundance of the HAB-related ribotypes in coastal and microcosm blooms. This study indicates the ability of electronic microarray platform to detect or monitor bacteria in natural and induced environments.

Different Competitive Outcomes Among Four Species ff Cladocerans Under Different Alga Combinations of Colonial Microcystis Spp. and Green Alga Scenedesmus Obliquus
Authors: Feizhou Chen1, 2, Ping Xie1 and Boqiang Qin2
Affiliations: Donghu Experimental Station of Lake Ecosystems, State Key Laboratory for Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, P.R. China, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, P.R. China
Source: Hydrobiologia, May 2007, 581(1): 209-215

Abstract: Cyanobacteria blooms (especially Microcystis spp.) are thought to alter dominance of large-sized daphnids into small-sized metazoan zooplankton. However, several field investigations show different phenomena. Laboratory experiments were conducted based on the hypothesis that different Microcystis spp. concentrations would influence competitive outcomes using two algal combinations of different concentrations and four species of cladocerans. In the algal combination of 50 mg l–1 colonial Microcystis spp. + 1 mg l–1 Scenedesmus obliquus (fresh weight), Daphnia carinata was absent during the experiment in competition with other cladocerans. Decreasing colonial Microcystis spp. concentration (10 mg l–1) resulted in a shift from dominance by small-sized cladocerans to dominance by D. carinata. No significant effects of different concentrations of colonial Microcystis spp. on competitive outcomes were shown among three small-sized cladocerans. These results support the idea that cyanobacteria concentration affects the dominance status of large-bodied daphnid.

Dynamics of Microcystin-Producing and Non-Microcystin-Producing Microcystis Populations is Correlated with Nitrate Concentration in a Japanese Lake
Authors: Mitsuhiro Yoshida, Takashi Yoshida, Yukari Takashima, Naohiko Hosoda, Shingo Hiroishi
Affiliations: Takashi Yoshida, Department of Marine Bioscience, Fukui Prefectural University, Obama-City, Fukui, Japan, 1Department of Marine Bioscience, Fukui Prefectural University, Obama-City, Fukui, Japan
Source: FEMS Microbiology Letters, January 2007, 266(1):49-53

Abstract: Temporal changes in hepatotoxin microcystin-producing and non-microcystin-producing Microcystis aeruginosa populations were examined in Lake Mikata, Japan. To monitor the densities of the total M. aeruginosa population and the potential microcystin-producing subpopulation, we used a quantitative real-time PCR assay targeting the phycocyanin intergenic spacer and the microcystin synthetase gene (mcyA), respectively. During the sampling period, the ratio of the mcyA subpopulation to the total M. aeruginosa varied considerably, from 0.5% to 35%. When surface nitrate concentrations increased, there was a rise in the relative abundance of the mcyA subpopulation. This was a positive correlation with the nitrate concentrations (r=0.53, P‹0.05, n=14); whereas temperature and ortho-phosphate had no significant correlation with the presence of mcyA. Our data suggest that high nitrate loading may be a significant factor promoting the growth of the microcystin subpopulations within M. aeruginosa communities in Lake Mikata.

Effect of Chlorination on Microcystis aeruginosa Cell Integrity and Subsequent Microcystin Release and Degradation
Authors: Robert I. Daly, Lionel Ho,* and Justin D. Brookes
Affiliations: CRC for Water Quality and Treatment, Australian Water Quality Centre, SA Water Corporation, PMB 3, Salisbury, SA 5108, Australia, and School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
Source: Environmental Science Technology, 9 May 2007, 41(12):4447

Abstract: The proliferation of cyanobacteria in drinking water sources is problematic for water authorities as they can interfere with water treatment processes. Studies have shown that oxidants such as chlorine can enhance the coagulation of cyanobacteria; however, chlorine can potentially lyse cyanobacterial cells, releasing toxic metabolites. Chlorine also has the potential to effectively degrade these toxins. This study evaluated the effect of chlorine on the cell integrity of toxic Microcystis aeruginosa in reservoir water using flow cytometry. In addition, the effect of chlorine on the subsequent release and degradation of microcystin toxins was systematically assessed. Cell lysis occurred at chlorine exposure values between 7 and 29 mg min/L, which is within the range of normal disinfection practices. Intracellular toxin was shown to be released from damaged cells at a rate three times faster than it was degraded by chlorine. The degradation of extracellular microcystin by chlorine was found to be dependent upon the pH, chlorine exposure, and the presence of cyanobacterial cells.

The Effect of Temperature on Growth Characteristics and Competitions of Microcystis Aeruginosa and Oscillatoria Mougeotii in A Shallow, Eutrophic Lake Simulator System
Authors: Zhaosheng Chu¹, Xiangcan Jin¹ , Norio Iwami¹ and Yuhei Inamori²
Affiliations: Research Center for Lake Ecology & Environments, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Ibaraki 305-0053, Japan
Source: Hydrobiologia, 16 March 2007, 581(1): 217-223

Abstract: Blue-green algal blooms formed by Microcystis and Oscillatoria often occur in shallow eutrophic lakes, such as Lake Taihu (China) and Lake Kasumigaura (Japan). Growth characteristics and competitions between Microcystis aeruginosa and Oscillatoria mougeotii were investigated using lake simulator systems (microcosms) at various temperatures. Oscillatoria was the superior competitor, which suppressed Microcystis, when temperature was ‹20°C, whereas the opposite phenomenon occurred at 30°C. Oscillatoria had a long exponential phase (20 day) and a low growth rate of 0.22 day–1 and 0.20 day–1 at 15°C and 20°–C, respectively, whereas Microcystis had a shorter exponential phase (2–3 days) at 30°–C and a higher growth rate (0.86 day–1). Interactions between the algae were stronger and more complex in the lake simulator system than flask systems. Algal growth in the lake simulator system was susceptible to light attenuation and pH change, and algae biomasses were lower than those in flasks. The outcome of competition between Microcystis and Oscillatoria at different temperatures agrees with field observations of algal communities in Lake Taihu, indicating that temperature is a significant factor affecting competition between Microcystis and Oscillatoria in shallow, eutrophic lakes.

Effects of Limiting Nutrients and N:P Ratios on the Phytoplankton Growth in a Shallow Hypertrophic Reservoir
Authors: Ho-Sub Kim, Soon-Jin Hwang, Jae-Ki Shin, Kwang-Guk An and Chun Gyeong Yoon1
Affiliations: Han River Environmental Research Laboratory, National Institute of Environmental Research, Gyeonggi, 476-823, Korea, Korea Institute of Water and Environment, Korea Water Resources Corporation, Daejon, 305-730, Korea School of Bioscience and Biotechnology, Chungnam National University, Daejon, 305-764, Korea, Present address: Watershed Management Research Division, National Institute of Environmental Research, Inchon, 404-170, Korea
Source Hydrobiologia, May 2007, 581(1): 255-267

Abstract: The purpose of this study was to evaluate the effects of limiting nutrients and the N:P ratios on the growth of phytoplankton (mainly cyanobacteria) in a shallow hypertrophic reservoir between November 2002 and December 2003. Nutrient enrichment bioassays (NEBs) were conducted, along with analyses of seasonal ambient nutrients and phytoplankton taxa, in the reservoir. The average DIN:TDP and TN:TP mass ratios in the ambient water were 90 (range: 17–187) and 34 (13–60), respectively, during the study period. The dissolved inorganic phosphorus showed seasonal variation, but less than that of inorganic nitrogen. The TN:TP ratios ranged from 13 to 46 (mean: 27 ± 6) during June–December when the cyanobacteria, Microcystis, dominated the phytoplankton composition. The NEBs showed that phytoplankton growth was mainly stimulated by the phosphorus (all of total 17 cases), rather than the nitrogen concentration (8 of 17 cases). The rapid growth rate of cyanobacteria was evident with TN:TP ratios less than 30. According to the results of the NEBs with different N concentrations (0.07, 0.7 and 3.5 mg l–1), but the same N:P ratios and when the nitrogen concentration was highest, the cyanobacterial growth reached a maximum at N:P ratios ‹1. Overall, the response of cyanobacterial growth was a direct function of added phosphorus in the NEBs, and was greater with increased N concentrations. Thus, cyanobacterial blooms favored relatively low N:P ratios in this hypertrophic reservoir system.

Effects of Nonylphenol on the Growth and Microcystin Production of Microcystis Strains
Authors: Wang J, Xie P, Guo N.
Affiliations: Donghu Experimental Station of the Lake Ecosystems, The State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China.
Source: Environment Resource, January 2007, 103(1): 70-78

Abstract: Both organic pollution and eutrophication are prominent environmental issues concerning water pollution in the world. It is important to reveal the effects of organic pollutants on algal growth and toxin production for assessing ecological risk of organic pollution. Since nonylphenol (NP) is a kind of persistent organic pollutant with endocrine disruptive effect which exists ubiquitously in environments, NP was selected as test compound in our study to study the relationship between NP stress and Microcystis growth and microcystin production. Our study showed that responses of toxic and nontoxic Microcystis aeruginosa to NP stress were obviously different. The growth inhibition test with NP on M. aeruginosa yielded effect concentrations E(b)C(50) values within this range of 0.67-2.96 mg/L. The nontoxic M.aeruginosa strains were more resistant to NP than toxic strains at concentration above 1mg/L. Cell growth was enhanced by 0.02-0.2 mg/L NP for both toxic and nontoxic strains, suggesting a hormesis effect of NP on M. aeruginosa. Both toxic and nontoxic strains tended to be smaller with increasing NP. But with the increased duration of the experiment, both the cell size and the growth rate began to resume, suggesting a quick adaptation of M. aeruginosa to adverse stress. NP of 0.05-0.5 mg/L significantly promoted microcystin production of toxic strain PCC7820, suggesting that NP might affect microcystin production of some toxic M. aeruginosa in the field. Our study showed that microcystin excretion was species specific that up to 75% of microcystins in PCC7820 were released into solution, whereas ›99% of microcystins in 562 remained in algal cells after 12 days' incubation. NP also significantly influenced microcystin release into cultural media. The fact that NP enhanced growth and toxin production of M. aeruginosa at low concentrations of 0.02-0.5 mg/L that might be possibly found in natural freshwaters implies that low concentration of NP may favor survival of M. aeruginosa in the field and may play a subtle role in affecting cyanobacterial blooms and microcystin production in natural waters.

Functional Analysis of Pilt From the Toxic Cyanobacterium Microcystis Aeruginosa PCC 7806
Authors: Kenlee Nakasugi, Ralitza Alexova, Charles J. Svenson, and Brett A. Neilan*
Affiliations: School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
Source: Journal of Bacteriology, March 2007, 189(5), 1689-1697

Abstract: The evolution of the microcystin toxin gene cluster in phylogenetically distant cyanobacteria has been attributed to recombination, inactivation, and deletion events, although gene transfer may also be involved. Since the microcystin-producing Microcystis aeruginosa PCC 7806 is naturally transformable, we have initiated the characterization of its type IV pilus system, involved in DNA uptake in many bacteria, to provide a physiological focus for the influence of gene transfer in microcystin evolution. The type IV pilus genes pilA, pilB, pilC, and pilT were shown to be expressed in M. aeruginosa PCC 7806. The purified PilT protein yielded a maximal ATPase activity of 37.5 ± 1.8 nmol Pi min–1 mg protein–1, with a requirement for Mg2+. Heterologous expression indicated that it could complement the pilT mutant of Pseudomonas aeruginosa, but not that of the cyanobacterium Synechocystis sp. strain PCC 6803, which was unexpected. Differences in two critical residues between the M. aeruginosa PCC 7806 PilT (7806 PilT) and the Synechocystis sp. strain PCC 6803 PilT proteins affected their theoretical structural models, which may explain the nonfunctionality of 7806 PilT in its cyanobacterial counterpart. Screening of the pilT gene in toxic and nontoxic strains of Microcystis was also performed.

Impacts of Cultivation of Marine Diatoms on the Associated Bacterial Community
Authors: Melanie Sapp, Antje Wichels, and Gunnar Gerdts
Affiliation: Alfred Wegener Institute Foundation for Polar and Marine Research, Biologische Anstalt Helgoland, P.O. Box 180, 27483 Helgoland, Germany
Source: Applied and Environmental Microbiology, March 7, 2007, 73(9):3117-3120

Abstract: The composition of bacterial communities associated with four diatom species was monitored during isolation and cultivation of algal cells. Strong shifts in the associated communities, linked with an increase in the numbers of phylotypes belonging to members of the Gammaproteobacteria, were observed during cultivation.

Intracellular Phosphorus Metabolism and Growth of Microcystis Aeruginosa in Dark/Light Cycles Under Various Redox Potential Difference Conditions
Authors: Xiaoli Shi, Liuyan Yang , Lijuan Jiang, Fanxiang Kong, Boqiang Qin and Guang Gao
Affiliations: Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, P.R. China, State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210093, P.R. China
Source: Hydrobiologia, March 16, 2007, 581(1): 167-176

Abstract Phosphorus metabolism and growth of M. aeruginosa were studied under three different conditions of diel fluctuation in redox potential. Redox potential in the culture increased in light and decreased in dark in all treatments except one, when cysteine was added in darkness. Total phosphorus content in M. aeruginosa decreased in darkness and increased in light during exponential growth but increased continuously in the stationary phase. Conversely, polyphosphate (PolyP) accumulated in darkness but was lost in the light. Low redox potential in darkness promoted PolyP accumulation. Polyglucose and soluble orthophosphate may provide energy and phosphorus, respectively, for PolyP synthesis. PolyP was important to M. aeruginosa survival during poor growth conditions. If the redox potential difference in the dark/light cycle was large, M. aeruginosa initially grew faster, but soon lost viability.

loning and Characterization of a New Hetero-Gene Cluster of Nonribosomal Peptide Synthetase and Polyketide Synthase from the Cyanobacterium Microcystis Aeruginosa K-139.
Authors: Nishizawa A, Arshad AB, Nishizawa T, Asayama M, Fujii K, Nakano T, Harada K, Shirai M.
Affiliation: Laboratory of Molecular Genetics, College of Agriculture, Ibaraki University, Ibaraki, Japan.
Source: Journal of General and Applied Microbiology, February 2007, 53(1):17-27

Abstract: Two nonribosomal peptide synthetase genes responsible for the biosynthesis of microcystin and micropeptin in Microcystis aeruginosa K-139 have been identified. A new nonribosomal peptide synthetase gene, psm3, was identified in M. aeruginosa K-139. The gene is a cluster extending 30 kb and comprising 13 bidirectionally transcribed open reading frames arranged in two putative operons. psm3 encodes four adenylation proteins, one polyketide synthase, and several unique proteins, especially Psm3L consisting of halogenase, acyl-CoA binding protein-like protein, and acyl carrier protein. Alignment of the binding pocket of the adenylation domain and an ATP-PPi exchange analysis using a recombinant protein with the adenylation domain of Psm3B showed that Psm3G and Psm3B activate aspartic acid and tyrosine, respectively. Although disruption of psm3 did not reveal the product produced by Psm3, we identified microviridin B and aeruginosin K139 in the cells of M. aeruginosa K-139. The above-mentioned results indicated that M. aeruginosa possesses at least five nonribosomal peptide synthetase gene clusters.

Laboratory Tests of Ammonium and Barley Straw Extract as Agents to Suppress Abundance of the Harmful Alga Prymnesium Parvum and its Toxicity to Fish
Authors: James P. Grover, Jason W. Baker, Fabiola Ureña-Boeck, Bryan W. Brooks , Reagan M. Errera, Daniel L. Roelkeand Richard L. Kiesling
Affiliations: Department of Biology, Program in Environmental and Earth Sciences, Box 19498, The University of Texas at Arlington, Arlington, TX 76019, USA Department of Environmental Studies, Center for Reservoir and Aquatic Systems Research, Baylor University, One Bear Place #97266, Waco, TX 76798-7266, USAcSection of Ecology and Evolutionary Biology, Departments of Wildlife and Fisheries Sciences, and Oceanography, Texas A&M University, 2258 TAMUS, College Station, TX 77843-2258 USA, Environmental Sciences Institute, 1 University Station, C-1100, University of Texas at Austin, TX 78712-0254, USA
Source: Water Resource, March 9, 2007, 41(12): 2503-2512

Abstract: Prymnesium parvum is a harmful alga whose blooms can cause fish kills in brackish waters. Two potential suppressants of this alga were tested, ammonium and barley straw extract (BSE), at temperatures of 10, 20 and 30 °C. Laboratory batch cultures were grown for 3 weeks at each temperature, with weekly doses of ammonium or BSE at either low or high levels, or a no-dose control treatment. The growth rate of P. parvum during exponential phase was highest at 20 °C and lowest at 10 °C, and was stimulated by the highest ammonium dose. Only cultures grown at 20 °C were toxic to fish. The highest ammonium dose abolished such toxicity and reduced the endpoint population density of P. parvum. BSE did not reduce the exponential growth rate, endpoint density, or toxicity to fish of P. parvum. The results support the use of ammonium additions, but not BSE, to suppress harmful blooms of P. parvum in those circumstances where the possible disadvantages can be managed.

The Microbial Community Structure in Petroleum-Contaminated Sediments Corresponds to Geophysical Signatures
Authors: Jonathan P. Allen, Estella A. Atekwana, Eliot A. Atekwana, Joseph W. Duris, D. Dale Werkema, and Silvia Rossbach
Affiliations: Department of Biological Sciences, Western Michigan University, Kalamazoo, Michigan 49008-5410, T. Boone Pickens School of Geology, Oklahoma State University, 105 Noble Research Center, Stillwater, Oklahoma 74078-3031, Characterization and Monitoring Branch, Environmental Sciences Division, National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Las Vegas, Nevada 89119
Source: Applied and Environmental Microbiology, February 24, 2007, 73(9): 2860-2870

Abstract: The interdependence between geoelectrical signatures at underground petroleum plumes and the structures of subsurface microbial communities was investigated. For sediments contaminated with light non-aqueous-phase liquids, anomalous high conductivity values have been observed. Vertical changes in the geoelectrical properties of the sediments were concomitant with significant changes in the microbial community structures as determined by the construction and evaluation of 16S rRNA gene libraries. DNA sequencing of clones from four 16S rRNA gene libraries from different depths of a contaminated field site and two libraries from an uncontaminated background site revealed spatial heterogeneity in the microbial community structures. Correspondence analysis showed that the presence of distinct microbial populations, including the various hydrocarbon-degrading, syntrophic, sulfate-reducing, and dissimilatory-iron-reducing populations, was a contributing factor to the elevated geoelectrical measurements. Thus, through their growth and metabolic activities, microbial populations that have adapted to the use of petroleum as a carbon source can strongly influence their geophysical surroundings. Since changes in the geophysical properties of contaminated sediments parallel changes in the microbial community compositions, it is suggested that geoelectrical measurements can be a cost-efficient tool to guide microbiological sampling for microbial ecology studies during the monitoring of natural or engineered bioremediation processes.

A Molecular Fingerprint Technique to Detect Pollution-Related Changes in River Cyanobacterial Diversity
Authors: Virginia Rodríguez, Daniel Aguirre de Cárcer, Virginia Loza, Elvira Perona and Pilar Mateo
Affilliation: Departamento de Biología, Universidad Autónoma de Madrid, Spain
Source: Journal of Environmental Quality, January 27, 2007, 36: 464-468

Abstract: Humans now have a strong influence on almost every major aquatic ecosystem, and our activities have dramatically altered the quality of receiving waters worldwide. Thus, there is a continuous need to develop and apply novel and effective technologies to detect, manage, and correct human-induced degradation of aquatic systems. In the present work, we evaluated the molecular approach using polymerase chain reaction (PCR)-temperature gradient gel electrophoresis (TGGE) to measure changes in cyanobacterial diversity along a pollution gradient in a river and compared it with that of using microscopic observations of field-fixed and cultured samples. The different 16S rDNA genes present in the cyanobacterial community of each sampling point of the river were separated by TGGE, giving a characteristic pattern of bands for each site. This pattern represents a “fingerprint” of the community, allowing direct comparisons of the different samples. The TGGE results revealed that the structure of the cyanobacterial community differed along the pollution gradient of the river. Microscopic and molecular approaches showed that cyanobacterial diversity decreased in a downstream direction. Similar results were obtained by the two methods, as indicated by the high correlation between them. We suggest PCR-TGGE could be a useful and rapidly applied technique for the routine analysis of changes in cyanobacterial diversity in response to pollution, which would allow us to monitor rivers in surveillance networks of watercourse quality.

Molecular Techniques for the Early Warning of Toxic Cyanobacteria Blooms in Freshwater Lakes and Rivers
Authors: Saker ML, Vale M, Kramer D, Vasconcelos VM.
Affiliations: Centro Interdisciplinar de Investigacao Marinha e Ambiental, Rua dos Bragas 289, 4050, Porto, Portugal,
Source: Applied Microbiology Biotechnology January 13, 2007

Abstract: The aim of this work was to test the efficacy of molecular techniques for detecting toxigenic cyanobacteria in environmental water samples collected from freshwater lakes, rivers and reservoirs in Portugal. Of 26 environmental samples tested, 21 were found to contain Microcystis using a genus-specific polymerase chain reaction (PCR). Another primer pair was applied to the same DNA template to test for the presence of microcystin synthetase genes. This primer pair resulted in the formation of a PCR product in 15 of the samples containing Microcystis and one sample that did not give a positive result in the Microcystis genus-specific PCR. A restriction assay using the enzyme EcoRV was then applied to show that in most cases, the gene fragment was from toxigenic strains of Microcystis and, in one above-mentioned case, from a microcystin-producing strain of Planktothrix. All environmental samples were examined microscopically to confirm the presence of cyanobacteria species. Samples were also tested for the presence of microcystins using the ELISA plate assay. There was good agreement between the results obtained with molecular techniques and those obtained from microscopy and chemical methods. The PCR techniques applied in this paper were found to be useful, particularly when the concentration of the target organism was very low compared with other organisms. This technique can be used to detect inocula for cyanobacterial populations and therefore provide a useful tool for assessing under which conditions particular species can grow into bloom populations.

Nutrient Limitation of Benthic Algae In Lake Michigan: The Role of Silica
Authors: Hunter J. Carrick, Rex L. Lowe
Affiliations: Hunter J. Carrick School of Forest Resources, Pennsylvania State University, University Park, Pensylvania 16802, USA2, and Rex L. LowebbDepartment of Biological Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA aSchool of Forest Resources, Pennsylvania State University, University Park, Pennsylvania 16802, USA, bDepartment of Biological Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA
Source: Journal of Phycology, April 2007, 43(2): 228

Abstract: In the Laurentian Great Lakes, phytoplankton growth and biomass are secondarily limited by silica (Si), as a result of phosphorus (P) enrichment. Even modest levels of P enrichment can induce secondary Silimitation, which, in turn, promotes a shift from the native diatom phytoplankton flora to chlorophyte and cyanobacteria species. However, very little is known about the nutritional status of benthic populations and their response to nutrient enrichment. Two experiments were performed in the littoral zone of Lake Michigan where nutrients were delivered to in situ benthic algal (episammic and epilithic) assemblages using nutrient-diffusing substrata. In order to test the hypothesis that benthic algae in Lake Michigan are Si limited, a 2 × 3 factorial experiment was used to deliver all combinations of Si, N, and P to resident assemblages growing on artificial substrata composed of natural (Si rich) versus calcium carbonate (Si poor) sand. A second experiment utilized a serial enrichment to evaluate the role of Si in mediating changes in taxonomic composition. These findings indicate that benthic algae in Lake Michigan exhibit signs of secondary Si limitation, and that their response to enrichment is similar to the phytoplankton. Moreover, natural sand substrata may provide a source of Si to resident benthic algae.

Nutrient Limitation of Benthic Algae In Lake Michigan: The Role of Silica
Authors: Hunter J. Carrick, Rex L. Lowe
Affiliations: Hunter J. CarrickaaSchool of Forest Resources, Pennsylvania State University, University Park, Pensylvania 16802, USA2, and Rex L. LowebbDepartment of Biological Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA aSchool of Forest Resources, Pennsylvania State University, University Park, Pennsylvania 16802, USA, bDepartment of Biological Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA
Source: Journal of Phycology, April 2007, 43(2): 228

Quantitative Studies on Phosphorus Transference Occuring Between Microcystis Aeruginosa and its Attached Bacterium (Pseudomonas Sp.)
Authors: Lijuan Jiang, Liuyan Yang , Lin Xiao, Xiaoli Shi, Guang Gao and Boqiang Qin
Affiliations: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 22 Hankou Road, Nanjing, 210093, P. R. China Nanjing Institute of Geography and Limnology, CAS, 73 East Beijing Road, Nanjing, 210008, P. R. China
Source: Hydrobiologia, May 2007, 581(1): 161-165

Abstract: Phosphorus release from Microcystis aeruginosa and attached bacterium (Pseudomonas sp.) isolated from Lake Taihu was examined using a phosphorus isotope tracer in order to investigate the phosphorus transference between the two species. Our results reveal that the amount of phosphorus released form 32P-saturated M. aeruginosa is determined by its growth phase and most of phosphorus is assimilated by Pseudomonas finally while the amount of phosphorus released from 32P-saturated Pseudomonas is also determined by the growth phase of M. aeruginosa and most of them are assimilated by M. aeruginosa. The results suggest that phosphorus transference occurs between M. aeruginosa and its attached Pseudomonas . This process makes microenvironment of mucilage of M. aeruginosa attached bacteria maintain relative high amounts of phosphorus. Attached bacteria may be a temporary phosphorus bank to the growth of M. aeruginosa, and assimilation of phosphorus by M. aeruginosa becomes easy when M. aeruginosa is in lag growth phase. Thus, the phosphorus exchange between M. aeruginosa and attached Pseudomonas in microenvironment may be important to microfood web and cyanobacteria bloom.

Removal of Heavy Metals by the Nuisance Cyanobacteria Microcystis in Continuous Cultures: An Eco-Sustainable Technology
Authors: Prabhat Kumar Rai, B. D. Tripathi
Affiliations: Mizoram Central University. India, Centre of Environmental Science and Technology, Banaras Hindu University. India
Source: Environmental Sciences, January 2007, 4(1): 53-59

Abstract: The blue - green alga Microcystis was grown under continuous culture in the presence of chromium (VI), cadmium (II) and copper (II), as single metal species and as mixtures of two or three metals in a laboratory-scale system. The present work used artificial wastewater with low free ion activities due to the presence of a strong chelating agent EDTA but with total concentrations not appropriate for acceptable environments. Chromium (VI) and cadmium (II) had a positive interaction that increased the removal percentages of both these metals; the work, however, could not detect any interaction with copper (II). Microcystis was able to remove all the tested metals to some extent (24 - 76%), but bivalent metals were not removed as efficiently as reported in batch cultures. Chromium (VI) was more efficiently removed in continuous cultures than in batch culture, because the uptake of chromate could be favoured by actively growing algae. The work demonstrated the efficiency of Microcystis in metal removal from single bimetallic as well as multimetallic conditions. Since Microcystis is a nuisance and bloom-forming cyanobacteria, its biotechnological exploitation in metal removal at the field scale should follow an eco-sustainable approach.

Resistance to Glyphosate in the Cyanobacterium Microcystis Aeruginosa as Result of Pre-Selective Mutations
Authors: Victoria Lõpez-Rodas¹, Antonio Flores-Moya², Emilia Maneiro¹, Nieves Perdigones¹, Fernando Marva1, Marta E. García³ and Eduardo Costas¹
Affilliations: Genética (Producción Animal), Facultad de Veterinaria, Universidad Complutense, E-28040 Madrid, Spain, Biología Vegetal (Botánica), Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos s/n, E-29071 Málaga, Spain, Sanidad Animal (Microbiología), Facultad de Veterinaria, Universidad Complutense, E-28040 Madrid, Spain
Source: Evolutionary Ecology, July 2007, 21(4):535-547

Abstract: Adaptation of Microcystis aeruginosa (Cyanobacteria) to resist the herbicide glyphosate was analysed by using an experimental model. Growth of wild-type, glyphosate-sensitive (Gs) cells was inhibited when they were cultured with 120 ppm glyphosate, but after further incubation for several weeks, occasionally the growth of rare cells resistant (Gr) to the herbicide was found. A fluctuation analysis was carried out to distinguish between resistant cells arising from rare spontaneous mutations and resistant cells arising from other mechanisms of adaptation. Resistant cells arose by rare spontaneous mutations prior to the addition of glyphosate, with a rate ranging from 3.1 × 10–7 to 3.6 × 10–7 mutants per cell per generation in two strains of M. aeruginosa; the frequency of the Gr allele ranged from 6.14 × 10–4 to 6.54 × 10–4. The Gr mutants are slightly elliptical in outline, whereas the Gs cells are spherical. Since Gr mutants have a diminished growth rate, they may be maintained in uncontaminated waters as the result of a balance between new resistants arising from spontaneous mutation and resistants eliminated by natural selection. Thus, rare spontaneous pre-selective mutations may allow the survival of M. aeruginosa in glyphosate-polluted waters via Gr clone selection.

Role of Bipolar Pulsed DBD on the Growth of Microcystis Aeruginosa In Three-Phase Discharge Plasma Reactor
Authors: Cui-Hua Wang , Guo-Feng Li, Yan Wu, Yu Wan, Jie Li, Duan Li and Ning-Hui Wang
Affiliations: Institute of Electrostatic and Special Power, Dalian University of Technology, Dalian, 116024, Liaoning, P. R. China
Source: Plasma Chemistry and Plasma Processing and Springer Netherlands, February 2007, 27(1): 65-83

Abstract: Algae in drinking water supplies often bring about impact on the water treatment. In this study, a bipolar pulsed dielectric barrier discharge system in three-phase discharge plasma reactor was constructed for investigating its ability to control excessive growth of cyanobacteria, Microcystis aeruginosa. Experimental results show there was almost no change in optical density immediately after the interruption of electrical discharge, but the decreasing trend of optical density, cell density and chlorophyll-a content was obvious during the incubation period, indicating a significant residual effect of electrical discharge process on the algal growth inhibition. Scanning electron microscopy investigation of algae revealed surface damage, apparent leakage of intracellular contents and pores formed after electrical discharge process, which showed that algal cells had no potential to survive and grow. Compared with the control sample, it was observed that electrical discharge on the algal extracellular products has almost no residual effect and the growth rate of algae slightly decreased before three days storage. Hydrogen peroxide was produced by electrical discharge in the µM level and showed a first-order decay. But at such level, the external addition of hydrogen peroxide alone is not likely to cause the residual effect. These results implicated that the growth inhibition of M. aeruginosa was mainly caused by electrical discharge process, and it made the algal cells lose ability to survive, demonstrating the considerable potential of such an alternative process for efficient water purification.

Seasonal Occurrence and Toxicity of Microcystis in Impoundments of the Huron River, Michigan, USA.
Author: Lehman EM
Affiliations: Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA.
Source: Water Research, January 8, 2007, 41(4): 795-802

Abstract: Occurrence and toxicity of Microcystis spp. were measured by ELISA in three impoundments of the Huron River in southeast Michigan, USA. Assays were conducted weekly from June through October 2005. Additional samples were collected to assess microcystin concentrations throughout the drinking water treatment process at the Ann Arbor Water Treatment Facility. Water column stability, nutrient concentrations, and N:P ratios were examined as potential predictors of phycocyanin and microcystin. Microcystin was found in two of the impoundments at seasonally varying concentrations. Microcystis presence was associated with N:P ratios between 40 and 80 by moles, and toxin levels typically peaked one to two weeks after a peak in phycocyanin. The toxin was also detected at low levels at all stages of the drinking water treatment process. Freezing and thawing water samples prior to analysis yielded maximum microcystin assay concentrations. Experiments indicated that the competitive ELISA method is susceptible to false negative reporting. This is the first report of algal toxins in this catchment, and results demonstrate that sensitive and rapid analytical methods offer the chance to link the dynamics of toxin production with environmental conditions.

Seasonal Shifts in Chemotype Composition of Microcystis Sp. Communities in the Pelagial and the Sediment of a Shallow Reservoir
Authors: Martin Welker, Lenka Sejnohova, Danka Nemethova, Hans von Dohren, Jir Jarkovsky, Blahoslav Marsalek
Affiliations: Technische Universita t Berlin, Inst. Chemie-Biochem. und Mol. Biol., Franklinstr. 29, 10587 Berlin, Germany, Czech Academy of Sciences, Inst. Botany, Kvetna 8, 6036 Brno, Czech Republic, Masaryk University, Research Centre for Environmental Chemistry and Ecotoxicology and Centre of Biostatistics and Analyses, Kamenice 126/3, 625 00 Brno, Czech Republic, Technische Universita t Berlin, Inst. Chemie-Biochem. und Mol. Biol., Franklinstr. 29, 10587 Berlin, Germany, Masaryk University, Research Centre for Environmental Chemistry and Ecotoxicology and Centre of Biostatistics and Analyses, Kamenice 126/3, 625 00 Brno, Czech Republic, Czech Academy of Sciences, Inst. Botany; Kvetna 8, 6036 Brno, Czech Republic; Masaryk University, Research Centre for Environmental Chemistry and Ecotoxicology, Kamenice 126/3, 625 00 Brno, Czech Republic
Source: American Society of Limnology and Oceanography;Limnology Oceanography, 2007, 52(2):609–619

Abstract: The various oligopeptides produced by individual Microcystis clones enable the classification of individual colonies of Microcystis in distinct peptide chemotypes. The dynamics and diversity of coexisting chemotypes are regarded as major factors influencing the microcystin-content of blooms of this potentially toxic cyanobacterial genus. We compared the chemotype composition in planktonic and benthic Microcystis communities in Brno reservoir (Czech Republic) from July to November 2004 by single colony mass spectrometry (n 5 783). Ninetytwo peptides were selected to characterize 37 chemotypes as revealed by K-means clustering. In the course of the season the Microcystis community became significantly less diverse (linear regression of Shannon indices, p , 0.001) in the pelagic, and in November two chemotypes–both of which did not contain microcystins–accounted for nearly 80% of the colonies. In contrast, other chemotypes that were dominant in the pelagic in July were no longer encountered after August, whereas some chemotypes that never accounted for high relative abundances were encountered throughout the season. The shift to some few dominant chemotypes in the pelagic was also reflected by changes in the benthic community where the same chemotypes increased in relative abundances. Nonetheless, chemotypes were identified in the sediment in July and November that were never found in plankton samples. A principal component analysis revealed that communities in the pelagial and the benthal were very different in July but converged during the season because of the deposition of dominant planktonic chemotypes in the sediment. In accordance with the declining percentage of toxin-producing Microcystis colonies, the microcystin content of seston samples decreased significantly from 0.9 mg g21 dry weight to levels below the detection limit (linear regression, p › 0.001).

Towards Clarification of the Biological Role of Microcystins, A Family of Cyanobacterial Toxins
Authors: Schatz D, Keren Y, Vardi A, Sukenik A, Carmeli S, Borner T, Dittmann E, Kaplan A.
Affiliations Department of Plant and Environmental Sciences, The Hebrew University, 91904 Jerusalem, Israel
Source: Environmental Microbiology, April 2007, 9(4): 965-70

Abstract: Microcystins constitute a serious threat to the quality of drinking water worldwide. These protein phosphatase inhibitors are formed by various cyanobacterial species, including Microcystis sp. Microcystins are produced by a complex microcystin synthetase, composed of peptide synthetases and polyketide synthases, encoded by the mcyA-J gene cluster. Recent phylogenetic analysis suggested that the microcystin synthetase predated the metazoan lineage, thus dismissing the possibility that microcystins emerged as a means of defence against grazing, and their original biological role is not clear. We show that lysis of Microcystis cells, either mechanically or because of various stress conditions, induced massive accumulation of McyB and enhanced the production of microcystins in the remaining Microcystis cells. A rise in McyB content was also observed following exposure to microcystin or the protease inhibitors micropeptin and microginin, also produced by Microcystis. The extent of the stimulation by cell extract was strongly affected by the age of the treated Microcystis culture. Older cultures, or those recently diluted from stock cultures, hardly responded to the components in the cell extract. We propose that lysis of a fraction of the Microcystis population is sensed by the rest of the cells because of the release of non-ribosomal peptides. The remaining cells respond by raising their ability to produce microcystins thereby enhancing their fitness in their ecological niche, because of their toxicity.

Vitamins, Phytoplankton and Bacteria: Symbiosis or Scavenging?
Author: M. R. Droop
Affiliations: Scottish Association For Marine Science, Dunstaffnage Marine Research Laboratory, Oban, Argyll, PA37 1QA, Scotland
Source: Journal of Plankton Research January 19, 2007 29(2):107-113

Abstract: The conclusion that over 25% of global primary production depends on direct algal/bacterial symbiosis involving vitamin B12 [Croft et al., (2005) Algae acquire vitamin B12 through a symbiotic relationship with bacteria. Nature, 438, 90–93] is patently false, for it is based on a misconception of the probable level of the vitamin B12 requirement in marine pelagic algae. A review of the various published attempts at measuring this requirement suggests that it is likely to be so low that oceanic and coastal concentrations of the vitamin would usually be sufficient to sustain the populations that occur without the assistance of direct algal/bacterial symbiosis. The levels measured are discussed in relation to method (batch or continuous culture) and protocols used. Requirement values considered by the author to be acceptable range from 0.1 to 0.3 pM for the vitamin growth saturation constant (KS) and from 30 to 100 µL algal biomass pmol–1 vitamin for the yield.

2006

Assessment of Phosphorus-microbe Interactions in Lake Ontario by Multiple Techniques
Authors: Sandra P. Gouvêa, Christyanne Melendez, Matthew J. Carberry, George S. Bullerjahn, Steven W. Wilhelm, Tom A. Langen and Michael R. Twiss
Sources: Journal of Great Lakes Research, International Association of Great Lakes Research, 2006, 32(3): 455-470

Abstract Conventional and newly-developed techniques to determine the phosphorus (P) status of Lake Ontario phytoplankton were employed in September 2003, immediately after the passage of the storm system associated with Hurricane Isabel. Surface water (1–5 m) was collected at 29 stations, with selected stations sampled throughout the water column. Chemical estimates of total P concentrations were compared with proxies of P bioavailability: P enrichment bioassays of lake water, alkaline phosphatase activity (APA), and P-dependent bioreporter assays. Average total P (314 nM) and total chlorophyll-a (2.12 xg/L) concentrations measured in pelagic surface waters from throughout Lake Ontario suggest an oligotrophic status prevailed across much of this lake during the sample period. Autotrophic picoplankton (0.22 xm) displayed the highest growth rates and were grazed at the highest rate, whereas P-enrichment bioassays favored the production of autotrophic nanoplankton (2–20 xm) and autotrophic microplankton (› 20 xm) biomass. Average concentrations of bacteria (2.61 x 1010 cells/L) were higher than those measured during summer in a similar lake (Erie), whereas the average viral density (1.38 x 1010 virus particles/L) was similar. Pelagic stations exhibited higher APA than coastal stations; cyanobacterial bioreporter responses did not show high correlation with APA suggesting that proxies of P-demand based on residual effects (e.g., enzyme production) were not indicative of shorter-term biological responses related to planktonic growth (bioreporter genetic response). The combination of traditional chemical, biochemical (APA), and cutting-edge biological methods (bioreporter) provided information on nutrient concentrations and primary productivity throughout Lake Ontario, while concurrently allowing real-time assessment of P bioavailability.

Development of Single-cell PCR Methods for the Raphidophyceae
Authors: A.K.L. Kai, Y.K. Cheung, P.K.K. Yeung and J.T.Y. Wong
Source: Harmful Algae, December 2006, 5(6): 649-657

Abstract: Many Raphidophytes are important algal bloom-forming species. Morphology-based identification of these species is often ambiguous, however, as many species are very similar in shape and size. To accurately detect the presence of these species in pre-bloom conditions, single-cell PCR is probably the most rapid and convenient method. However, direct single-cell PCRs with conserved primers are apparently not effective, probably due to the impermeability of the cell wall. We report here an effective detergent-based pre-PCR cell lysis method, which turned out to be a critical step for effective single-cell PCR of the Raphidophytes. Two PCR-based methods, nested SC-PCR and SC-RAPD, were evaluated. The nested SC-PCR involves two consecutive PCRs, the first of which is performed with the D1 and D2 primers (external primers) resulting in an amplification of a partial LSU rRNA gene. The second amplification is performed with primers targeting the LSU domain and specifically annealing to Chattonella ovata and Chattonella marina only. The SC-RAPD performed with the established random primers, RP1–RP4, produced unique haplotypes that could be exploited to differentiate the two Chattonella species. The assay was demonstrated to be sensitive, with the lowest detection limit of a single Raphidophyceae cell. The method developed is a valuable tool for the study of intra-specific variations of the Raphidophytes and represents a platform for further development of species-specific SC-RAPD for all members of the Raphidophyceae.

Development of Tolerance Against Toxic Microcystis aeruginosa in Three Cladocerans and the Ecological Implications
Author Nichun Guo and Ping Xie
Source: Environmental Pollution, October 2006, 143(3): 513-518

Abstract: This is the first experimental study to compare difference in the development of tolerance against toxic Microcystis among multi-species of cladocerans (Daphnia, Moina and Ceriodaphnia) pre-exposed to two M. aeruginosa PCC7820 strains (MC-containing and MC-free). Zooplankton were divided into S population (fed Scenedesmus), M-F population (fed Scenedesmus + MC-free Microcystis), and M-C population (fed Scenedesmus + MC-containing Microcystis). M-F and M-C populations were pre-exposed to Microcystis strains for 4 weeks, and their newborns were collected for experiments. A pre-exposure to MC-containing or MC-free Microcystis increased tolerance against toxic Microcystis. The marked increases in survival rate and median lethal time (LT50, 100–194% increase) in the M-C population of Ceriodaphnia suggest that small-sized cladocerans may develop stronger tolerance against Microcystis than large-sized ones when both groups are exposed to toxic Microcystis. This may explain why dominant Daphnia is usually replaced by small-sized cladocerans when cyanobacteria bloomed in summer in eutrophic lakes. Three cladocerans pre-exposed to Microcystis developed different tolerance against toxic Microcystis, explaining zooplankton succession with blooms.

Effects of Nutrients, Salinity, Ph and Light:Dark Cycle on the Production of Reactive Oxygen Species in the Alga Chattonella Marina
Authors: Wenhua Liua, Doris W.T. Au^a, Donald M. Anderson^b, Paul K.S. Lam^a and Rudolf S.S. Wu^a
Affiliations: ^aCentre for Coastal Pollution and Conservation, City University of Hong Kong, Kowloon, Hong Kong SAR, China, ^bBiology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, United States
Source: Journal of Experimental Marine Biology and Ecology, 3 August 2007, 346(1-2):76-86

Abstract: Experiments were carried out to investigate the effects of nutrients, salinity, pH and light:dark cycle on growth rate and production of reactive oxygen species (ROS) by Chattonella marina, a harmful algal bloom (HAB) species that often causes fish kills. Different nitrogen forms (organic-N and inorganic-N), N:P ratios, light:dark cycles and salinity significantly influenced algal growth, but not ROS production. However, iron concentration and pH significantly affected both growth and ROS production in C. marina. KCN (an inhibitor of mitochondrial respiration) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (an inhibitor of photosynthesis) had no significant effects on ROS production. Vitamin K3 (a plasma membrane electron shuttle) enhanced ROS production while its antagonist, dicumarol, decreased ROS production. Taken together, our results suggest that ROS production by C. marina is related to a plasma membrane enzyme system regulated by iron availability but is independent of growth, photosynthesis, availability of macronutrients, salinity and irradiance.

Environmental Controls of Cladophora Growth Dynamics in Eastern Lake Erie: Application of the Cladophora Growth Model (CGM)
Authors: Scott N. Higgins, Robert E. Hecky and Stephanie J. Guildford
Source: Journal of Great Lakes Research, International Association of Great Lakes Research, 2006, 32(3): 629-644

Abstract The Cladophora growth model (CGM) was used to estimate the importance of light, temperature, phosphorus, and self-shading on the spatial and temporal variability of Cladophora growth rates and biomass accrual in eastern Lake Erie during 2002. The CGM predicted that Cladophora growth was highly sensitive to spatial and temporal variations in soluble phosphorous concentration (SRP). Specifically the CGM predicted that: 1) Site-to-site differences in SRP concentration resulted in a 2x difference in depth-integrated biomass; 2) maximum growth rates were strongly influenced by SRP concentrations during periods of rapid biomass accrual (mid-June to mid-July); 3) inter-annual differences in SRP concentration during the spring period (~ 1 µ g/L) could result in up to a 3.5x difference in depth integrated biomass; 4) Spatial variations in water clarity could result in a 2x difference in depth-integrated biomass between sites, with variations betweens sites occurring primarily between 2–6 m depth; 5) the mid-summer sloughing phenomenon likely resulted from self-shading by the algal canopy; and 6) the seasonal growth pattern of Cladophora was strongly regulated by temperature.

Fiber-Optic Microarray for Simultaneous Detection of Multiple Harmful Algal Bloom Species
Authors: Ahn, Soohyoun; Kulis, David M.; Erdner, Deana L.; Anderson, Donald M.; Walt, David R.
Source: Applied and Environmental Microbiology, September 2006, 72(9): 5742-5749

Abstract: Harmful algal blooms (HABs) are a serious threat to coastal resources, causing a variety of impacts on public health, regional economies, and ecosystems. Plankton analysis is a valuable component of many HAB monitoring and research programs, but the diversity of plankton poses a problem in discriminating toxic from nontoxic species using conventional detection methods. Here we describe a sensitive and specific sandwich hybridization assay that combines fiber-optic microarrays with oligonucleotide probes to detect and enumerate the HAB species Alexandrium fundyense, Alexandrium ostenfeldii, and Pseudo-nitzschia australis. Microarrays were prepared by loading oligonucleotide probe-coupled microspheres (diameter, 3 µm) onto the distal ends of chemically etched imaging fiber bundles. Hybridization of target rRNA from HAB cells to immobilized probes on the microspheres was visualized using Cy3-labeled secondary probes in a sandwich-type assay format. We applied these microarrays to the detection and enumeration of HAB cells in both cultured and field samples. Our study demonstrated a detection limit of approximately 5 cells for all three target organisms within 45 min, without a separate amplification step, in both sample types. We also developed a multiplexed microarray to detect the three HAB species simultaneously, which successfully detected the target organisms, alone and in combination, without cross-reactivity. Our study suggests that fiber-optic microarrays can be used for rapid and sensitive detection and potential enumeration of HAB species in the environment

Hydrodynamic and Water Quality Modeling Study of Spatial and Temporal Patterns of Phytoplankton Growth in a Stratified Lake with Buoyant Incoming Flow, A
Authors: Eun Hye Na and Seok Soon Park
Source: Ecological Modeling, December 1, 2006, 199(3): 298-314

Abstract: A three-dimensional hydrodynamic and water quality model was applied to Lake Paldang, a lake in South Korea that is stratified by incoming flows. The spatial and temporal patterns of phytoplankton growth in this lake were determined from the model. The model was calibrated and verified using data measured under different hydrological conditions. The model results were in reasonable agreement with the field measurements, in both the calibration and verification phases. The distributions of water quality and residence time in the lake and phytoplankton response to changes in nutrient loads were examined with the model, and the influence of the hydrodynamics on phytoplankton response was analyzed. The simulation results indicated that Lake Paldang is an essentially phosphorus-limited system, but that phytoplankton growth is limited by low water temperature and short residence time during the winter and the summer monsoon period, respectively. The results of sensitivity analyses also suggested that the hydrodynamics within the lake may have an indirect influence on phytoplankton responses to changes in the limiting nutrient loads, and that reducing phosphorus loading from Kyoungan Stream should be a high priority policy for controlling algal blooms during the pre- and post-monsoon periods. From this study, it was concluded that the three-dimensional water quality model incorporating hydrodynamic processes could successfully simulate phytoplankton response to changes in nutrient loads and that it could become a useful tool for identifying the essential factors determining phytoplankton growth and for developing the best management policy for algal blooms in Lake Paldang.

Improved monitoring of HABs using autonomous underwater vehicles (AUV)
Authors: I.C. Robbins, G.J. Kirkpatrick, S.M. Blackwell, J. Hillier, C.A. Knight and M.A. Moline
Source: Harmful Algae, December 2006, 5(6): 749-761

Abstract Blooms of toxic algae are increasing in magnitude and frequency around the globe, causing extensive economic and environmental impacts. On the west coast of Florida, blooms of the toxic dinoflagellate Karenia brevis (Davis) have been documented annually for the last 30 years causing respiratory irritation in humans, fish kills, and toxin bioaccumulation in shellfish beds. As a result, methods need to be established to monitor and predict bloom formation and transport to mitigate their harmful effects on the surrounding ecosystems and local communities. In the past, monitoring and mitigation efforts have relied on visual confirmation of water discoloration, fish kills, and laborious cell counts, but recently satellite remote sensing has been used to track harmful algal blooms (HABs) along the Florida coast. Unfortunately satellite ocean color is limited by cloud cover, lack of detection below one optical depth, and revisit frequency, all of which can lead to extended periods without data. To address these shortcomings, an optical phytoplankton discriminator (OPD) was developed to detect K. brevis cells in mixed phytoplankton assemblages. The OPD was integrated into autonomous underwater vehicle (AUV) platforms to gather spatially and temporally relevant data that can be used in collaboration with satellite imagery to provide a 3D picture of bloom dynamics over time. In January 2005, a Remote Environmental Monitoring UnitS (REMUS) AUV with an OPD payload was deployed on the west coast of Florida to retrieve a similarity index (SI), which indicates when K. brevis dominates the phytoplankton community. SI was used to monitor a K. brevis bloom in relation to temperature, salinity, chlorophyll, and ocean currents. Current speed, SI, temperature, salinity, and chlorophyll a from the AUV were used to quantify a 1 km displacement of the K. brevis bloom front that was observed over the deployment period. The ability to monitor short term bloom movement will improve monitoring and predictive efforts that are used to provide warnings for local tourism and fishing industries. In addition, understanding the fine scale environmental conditions associated with bloom formation will increase our ability to predict the location and timing of K. brevis bloom formation. This study demonstrates the use of one autonomous platform and provides evidence that a nested array of AUVs and moorings equipped with new sensors, combined with remote sensing, can provide an early warning and monitoring system to reduce the impact of HABs.

Ingestion of the Dinoflagellate, Pfiesteria piscicida, by the Calanoid Copepod, Acartia tonsa
Authors: Roman, Michael R. {a}; Reaugh, Matthew L.; Zhang, Xinsheng
Source: Harmful Algae, September 2006, 5(4): 435-441.

Abstract The dinoflagellate, Pfiesteria piscicida, can form harmful algal blooms in estuarine environments. The dominant copepod species usually found in these waters is Acartia tonsa. We tested the ability of A. tonsa to graze the non-toxic zoospore stage of P. piscicida and thus serve as a potential biological control of blooms of this algal species. A. tonsa grazed the non-toxic zoospore stages of both a non-inducible P. piscicida strain (FDEPMDR23) and a potentially toxic strain (Tox-B101156) at approximately equal rates. Ingestion of P. piscicida increased with cell concentration and exhibited a saturated feeding response. Both the maximum number of cells ingested (Imax) and the slope of the ingestion curve (a) of A. tonsa feeding on P. piscicida were comparable to these ingestion parameters for A. tonsa fed similar-sized phytoplankton and protozoan species. When these laboratory ingestion rates were combined with abundance estimates of A. tonsa from the Pocomoke Estuary and Chesapeake Bay, we found that significant grazing control of the non-toxic zoospore stage of P. piscicida by A. tonsa would only occur at high copepod abundances (›é10 copepods L-1). We conclude that under most in situ conditions the potential biological control of blooms of P. piscicida is exerted by microzooplankton grazers. However, in the less saline portions of estuaries where maximum concentrations of copepods often occur with low abundances of microzooplankton, copepod grazing coefficients can be similar to the growth rates of P. piscicida.

Interactive Influences of Nutrient Loading, Zooplankton Grazing, and Microcystin Synthetase Gene Expression on Cyanobacterial Bloom Dynamics in a Eutrophic New York Lake
Authors:C.J. Gobler_a,, T.W. Davis^a, K.J. Coyne^b and G.L. Boyer^c
Affiliations: ^aMarine Sciences Research Center, Stony Brook University, Southampton, NY, United States, ^bCollege of Marine and Earth Studies, University of Delaware, Lewes, DE, United States, ^cChemistry Department, State University of New York, College of Environmental Science and Forestry, Syracuse, NY, United States
Source: Harmful Algae, January 2007, 6(1):119-133

Abstract: We investigated the dynamics and toxicity of cyanobacteria populations in Lake Agawam, a eutrophic New York lake, and concurrently conducted experiments to evaluate the contrasting effects of zooplankton (mesozooplankton and microzooplankton) grazing and nutrient loading on the abundance and toxin content of cyanobacteria populations. Molecular techniques were used to assess the presence and expression of the microcystin synthetase gene. Lake Agawam hosted dense blooms (›105 cells mL–1) of Microcystis sp. and Anabaena sp. with consistently elevated levels of microcystin (1.0–25 µg L–1) and lower levels of anatoxin-a ( 1.0 µg L–1 during late summer only). Polymerase chain reaction (PCR) analysis targeting the microcystin synthetase gene (mcyE) indicated that Microcystis sp., and not Anabaena sp., was responsible for microcystin production in this system. Moreover, reverse transcriptase PCR (RT-PCR) indicated that the Microcystis population expressed the mcyE gene during summer months, but that gene expression declined to undetectable levels during the fall as in situ cell densities in the lake declined. During summer, when there was elevated Microcystis densities (›8 × 104 cells mL–1) expressing mcyE, experimental Daphnia sp. enrichment did not alter algal biomass (100% of experiments; n = 6). However, during fall months when the mcyE gene expression was not detected and Microcystis densities were lower and declining (4 × 103 to 5 × 104 cells mL–1), zooplankton enrichment yielded significantly reduced (p ‹ 0.05) cyanobacteria biomass relative to control treatments in most experiments (80%; n = 4). In contrast to mesozooplankton, microzooplankton actively grazed algal biomass at significant rates (1.2 ± 0.3 day–1) throughout the study. Microcystis and other cyanobacterial populations did not respond to nutrient amendments during early summer but experienced significantly increased growth rates and toxin concentrations (microcystin and anatoxin-a) during late summer and early fall nitrogen enrichment experiments. As such, the dominance of Microcystis sp. blooms during the summer was linked to nutrient replete conditions and the suppression of mesozooplankton (but not microzooplankton) grazing which itself appeared to be influenced by cellular toxin synthesis by Microcystis. The demise of the bloom was associated with N-limitation which reduced growth rates and toxin production by Microcystis and in turn may have permitted zooplankton to graze cells.

Methodology and Evaluation of a Highly Sensitive Algae Toxicity Test Based on Multiwell Chlorophyll Fluorescence Imaging
Authors: Ulrich Schreiber, Pamela Quayle, Sven Schmidt, Beate I. Escher and Jochen F. Mueller
Source: Biosensors and Bioelectronics, November 20, 2006

Abstract A new phytotoxicity bioassay based on chlorophyll fluorescence imaging of algae suspensions in multiwell plates is introduced. Phytotoxicity is quantified via inhibition of photosystem II quantum yield, Y(II), assessed with the saturation pulse method. The basics of this approach as well as the factors enhancing and limiting its performance are outlined. Compared to other established techniques the new system allows exceptionally rapid and accurate measurements of phytotoxicity using pulse-amplitude-modulation (PAM) fluorometry. While instrument related errors are negligibly small, optimal performance depends on appropriate choice of algae and illumination conditions. Illustrative examples for the response of Phaeodactylum tricornutum to diuron are presented. The standard deviation involved in the Y(II) determination of a single well amounts to the equivalent of 44 ng/L diuron. A decisive role is played by the light (measuring light, saturation pulses, actinic light) to which samples are exposed during the bioassay: (1) the inhibitor response is enhanced at high measuring light intensity. (2) Saturation pulses may be considered non-invasive only, if applied at low frequency and as long as physiologically healthy algae cultures are used. (3) Continuous actinic light may be problematic, as it induces complex physiological reactions that limit the performance of the approach; it is not required for assessment of diuron-type inhibitors at high measuring light intensity.

Occurrence of the Toxin-producing Cyanobacterium Cylindrospermopsis raciborskii in Mona and Muskegon Lakes, Michigan
Authors: Ying Hong, Alan Steinman, Bopaiah Biddanda, Richard Rediske and Gary Fahnenstiel
Source: Journal of Great Lakes Research, International Association of Great Lakes Research, 2006, 32 (3): 645-652

Abstract The bloom-forming and toxin-producing cyanobacterium Cylindrospermopsis raciborskii was observed in Muskegon and Mona lakes, drowned river-mouth tributaries of Lake Michigan. Morphological features of the taxon were similar to those described elsewhere. The species was observed only in late summer; elevated bottom water temperature, and perhaps phosphorus concentration, appears to be implicated in its appearance. Maximum abundances at any given site reached 393 and 0.9 trichomes/mL in Mona Lake and Muskegon Lake, respectively. Although these concentrations are low relative to other reports, the presence of this species in these two lakes from adjacent watersheds adds to a growing body of literature that suggests the distribution of C. raciborskii is on the increase in northern latitudes.

Phytoplankton Vertical Distributions and Composition in Baltic Sea Cyanobacterial Blooms
Authors: Susanna Hajdu^a,, Helena Höglander^a and Ulf Larsson^a
Affiliations: aDepartment of Systems Ecology, Marine and Brackish Water Ecology, Stockholm University, SE-106 91 Stockholm, Sweden
Source: Harmful Algae, February 2007, 6(2):189-205

Abstract: We studied the vertical structure of the phytoplankton community in two toxic cyanobacterial blooms in the offshore Baltic Sea. In 1994, vertically separated potentially toxic, diazotrophic and mixotrophic species (belonging to Cyanophyceae, Dinophyceae and Prymnesiophyceae) dominated. In 1997, picocyanobacteria, mainly in colonies, made up 40–50% of the total phytoplankton carbon biomass in the top 20 m both day and night. Colony-forming species of picocyanobacteria seem to be occasionally important and hitherto underestimated in the Baltic Sea.

We found species-specific depth distribution patterns. Nodularia spumigena and Anabaena spp. were observed mainly above 10 m depth, while Aphanizomenon sp. was mostly found deeper, especially at night. Dinophysis norvegica was only abundant near the seasonal pycnocline and showed very limited diurnal migration. Other flagellates, including small Cryptophyceae and 10 identified Chrysochromulina species, occurred down to 40 m depth. Their vertical migration may help to retrieve nutrients from below the summer pycnocline.

We conclude that considerable differences in dominating functional groups may occur between years/bloom stages, and that the vertical distribution pattern of many species is recurring at similar environmental conditions, suggesting species-specific niche-separation.

The Potential Causes of Cyanobacterial Blooms in Baltic Sea Estuaries
Authors: Marcin Pliñski ^A1, Hanna Mazur-Marzec ^A1, Tomasz Józwiak ^A1, Justyna Kobos ^A1
Affiliations: ^A1 Department of Marine Biology and Ecology, Institute of Oceanography Gdansk University, Al. Marszaika Piisudskiego 46 81-378 Gdynia, Poland
Source: Oceanological and Hydrobiological Studies, March 2007, 36(1): 134 – 137 NOAA Seattle Journals

Abstract: Nodularia spumigena Mertens, Aphanizomenon flos-aquae (L.) Ralfs and some species of the genus Anabaena are the dominant cyanobacterial taxa occurring in the Gulf of Gdansk. The heterocystous cyanobacteria use dissolved molecular N2 as an additional nitrogen source, and this allows them to bloom during the summer when growth of other phytoplankton species is normally nitrogen-limited. Although cyanobacterial blooms have been reported in the Baltic Sea since the mid-19th century, the extent and intensity of blooms have recently increased due to anthropogenic sources of eutrophication. Increased river phosphorus input and changes in the phosphorus to nitrogen ratio are implicated as causal factors. After us the initial cause of the cyanobacterial bloom is a low N:P ratio, which indicates phosphorus excess, i.e. favourable nutrient conditions for nitrogen-fixing algae. An N:P ratio of 10 has been considered an approximate value for the N:P requirements of Baltic phytoplankton. For several years this ratio has been lower than 10.

The mean annual value of the N:P ratio for the water of the Gulf of Gdansk ranged from 3 to 7. Differences in the intensity of blooms observed in different years could be linked to temperature. During hot summers, when the seawater temperature increased to 20°C, large blooms were noted. For the cyanobacterial blooms in the Baltic Sea, the low N:P ratio is the primary factor and high temperature is a starting point.

Promotion of Harmful Algal Blooms by Zooplankton Predatory Activity
Authors: Mitra, Aditee; Flynn, Kevin J
Source: Biology Letters, June 2006, 2(2): 194-197

Abstract The relationship between algae and their zooplanktonic predators typically involves consumption of nutrients by algae, grazing of the algae by zooplankton, which in turn enhances predator biomass, controls algal growth and regenerates nutrients. Eutrophication raises nutrient levels, but does not simply increase normal predator-prey activity; rather, harmful algal bloom (HAB) events develop often with serious ecological and aesthetic implications. Generally, HAB species are outwardly poor competitors for nutrients, while their development of grazing deterrents during nutrient stress ostensibly occurs too late, after the nutrients have largely been consumed already by fast-growing non-HAB species. A new mechanism is presented to explain HAB dynamics under these circumstances. Using a multi-nutrient predator-prey model, it is demonstrated that these blooms can develop through the self-propagating failure of normal predator-prey activity, resulting in the transfer of nutrients into HAB growth at the expense of competing algal species. Rate limitation of this transfer provides a continual level of nutrient stress that results in HAB species exhibiting grazing deterrents protecting them from top-down control. This process is self- stabilizing as long as nutrient demand exceeds supply, maintaining the unpalatable status of HABs; such events are most.

Reflections on the Ballast Water Dispersal–Harmful Algal Bloom Paradigm
Author:Theodore J. Smayda^a
Affiliation: ^aGraduate School of Oceanography, University of Rhode Island, Kingston, RI 02281, United States
Source: Harmful Algae, August 2007, 6(4):601-622

Abstract:The ballast water dispersal–HAB paradigm, increasingly invoked circumstantially to explain puzzling and unaccountable HAB species outbreaks when lacking the multiple tests of confirmation recommended by Bolch and de Salas (2007), is evaluated. The types and examples of natural dispersions and taxon cycles are compared to exotic species bloom behavior linked to ballast water vectoring. The regional spreading, bloom behavior and disjunct distributions of the brown tide pelagophyte Aureococcus anophagefferens and the toxic dinoflagellate Gymnodinium catenatum, attributed to ballast water vectoring, are used as representative examples to evaluate the general application of the ballast water–HAB paradigm and associated interpretative problems. Human-aided emigration has a seeding and colonization ecology that differs from bloom ecology. For self-sustaining blooms to occur, these two ecologies must be accommodated by habitat growth conditions. The three stages that a non-native species must pass through (pioneering, persistence, community entry) to achieve colonization, community maintenance, and to bloom, and the niche-related factors and role of habitat disturbance are discussed. The relevance of cryptic occurrences, cyst deposits, dormancy periods and bloom rhythms of HAB species to their blooms attributed to ballast water-assisted introductions is also sketched. The different forms of HAB species rarity, their impact on the ballast water dispersal–HAB paradigm, and the dispersion and blooms of specialist and generalist HAB species are discussed. The remarkable novel and, often, monospecific blooms of dinoflagellate HAB species are being paralleled by similar eruptive bloom behavior cutting across phylogenetic lines, and being found also in raphidophytes, haptophytes, diatoms, silicoflagellates, etc. These blooms cannot be explained only as seeding events. An ecological release of ‘old barriers’ appears to be occurring generally at coastal bloom sites, i.e. something significant is happening ecologically and embedded within the ballast water–HAB paradigm. There may be a relationship between Life Form type [Smayda, T.J., Reynolds, C.S., 2001. Community assembly in marine phytoplankton: application of recent models to harmful dinoflagellate blooms. J. Plankton Res. 23, 447–461] and mode of expatriation; HAB dinoflagellate species commonly reported to produce ballast water-assisted toxic blooms invariably are members of cyst-producing Life Forms IV, V, VI. Ballast water vectoring of Life Forms I, II, III is rarely reported, even though many produce cysts, and where their novel introductions do occur they are more likely to be ichthyotoxic and vectored in shellfish stock consignments. The relevance of, and need to distinguish between morphospecies and their geographic/ribotype clades are discussed based on the Alexandrium tamarense/catenella/fundyense complex. Morphospecies-level ballast water dispersions are probably minor compared to the dispersal of the different ribotypes (toxic/non-toxic clades) making up HAB morphospecies; the redistribution and admixture of genotypes should be the focus. Ballast water-assisted expatriations impact the global occurrence of HABs through the direct transfer of previously absent species or introduction of genetic strains from the donor habitat that are ecologically favored over resident strains. The hybridization of species may be of potentially greater impact, resulting from the (1) mating of individuals from the donor and recipient habitats, or (2) through the interbreeding of strains introduced from two different donor sites into the recipient site, and whose progeny have greater ecological fitness than indigenous strains. Exceptional ecological changes of some sort appear to be occurring globally which, in combination with the genetically altered ecophysiological behavior of HAB species linked to ballast water dispersion and admixture, underpins the global HAB phenomenon. The impact of ballast water and shellfish transplantation on HABs and phytoplankton community ecology, generally, is considerably greater than the current focus on HAB species distributions, vectoring, and blooms. The methodological, investigative and conceptual potential of the ballast water–HAB paradigm should be exploited by developing a GEOHAB type intiative to advance quantification of global HAB ecology.

Regional Climate Change and Harmful Algal Blooms in the Northeast Atlantic
Authors: Edwards, M. {a}; Johns, D.G.; Leterme, S.C.; Svendsen, E.; Richardson, A.J.
Source: Limnology and Oceanography, March 2006, 51(2): 820-829.

Abstract We investigated long-term spatial variability in a number of Harmful Algal Blooms (HABs) in the northeast Atlantic and North Sea using data from the Continuous Plankton Recorder. Over the last four decades. Some Dinoflagellate taxa showed pronounced variation in the south and east of the North Sea, with the most significant increases being restricted to the adjacent waters off Norway. There was also a general decrease along the eastern coast of the United Kingdom. The most prominent feature in the interannual bloom frequencies over the last four decades was the anomalously high values recorded in the late 1980s in the northern and central North Sea areas. The only mesoscale area in the northeast Atlantic to show a significant increase in bloom formation over the last decade was the Norwegian coastal region. The changing spatial patterns of HAB taxa and the frequency of bloom formation are discussed in relation to regional climate change, in particular, changes in temperature, salinity, and the North Atlantic Oscillation (NAO). Areas highly vulnerable to the effects of regional climate change on HABs are Norwegian coastal waters and the Skagerrak. Other vulnerable areas include Danish coastal waters, and to a lesser extent, the German and Dutch Bight and the northern Irish Sea. Quite apart from eutrophication, our results give a preview of what might happen to certain HAB genera under changing climatic conditions in temperate environments and their responses to variability of climate oscillations Such as the NAO.

Resistance to Burial of Cyanobacteria in Stromatolites
Authors: Jacco C. Kromkamp^1,*, Rupert Perkins², Nicole Dijkman¹, Mireille Consalvey³, Miriam Andres⁴, R. Pamela Reid⁴
Affiliations: ¹Netherlands Institute of Ecology, Centre for Estuarine and Marine Ecology (NIOO-CEME), PO Box 140, 4400 AC Yerseke, The Netherlands, ²School of Earth, Ocean and Planetary Sciences, Cardiff University, Cardiff CF10 3YE, UK , ³National Institute of Water & Atmospheric Research (NIWA), Greta Point, Private Bag 14-901, Kilbirnie, Wellington, New Zealand , ⁴University of Miami/RSMAS-MGG, 4600 Rickenbacker Causeway, Miami, Florida 33149, USA
Source: Aquatic Microbial Ecology, 10 July 2007, 48(2):123-130

Abstract: Stromatolites are complex lithified structures with a well-defined layered structure thought to have been formed by trapping and binding of sediment particles by micro-organisms, especially cyanobacteria. Modern marine stromatolites in the Bahamas live in a high-energy environment (surf zone) and are regularly buried by moving sands. We investigated stromatolite cyanobacterial photophysiology ex situ, during and after sand burial using variable fluorescence studies. Buried samples inactivated their photosynthetic electron transport, but only when oxygen concentrations decreased to low levels. Post-burial, the stromatolite cyanobacterial community reactivated its photosynthetic activity within 1 to 2 h, but this activation was light dependent. It is therefore speculated that the redox state of the plastoquinone pool determines the inactivation/reactivation processes. The ability of cyanobacteria to survive and recover from burial by sediment could be a fundamental attribute that has contributed to the success of cyanobacteria as stromatolite builders and for the actual existence of stromatolites as organo-sedimentary structures with a putative presence spanning 3500 million yr.

Role of Selective Predation in Harmful Algal Blooms, The
Authors: Jordi Solé, Emilio Garcia-Ladona and Marta Estrada
Source: Aquatic Sciences and Fisheries, 2006

Abstract A feature of marine plankton communities is the occurrence of rapid population explosions. When the blooming species are directly or indirectly noxious for humans, these proliferations are denoted as harmful algal blooms (HAB). The importance of biological interactions for the appearance of HABs, in particular when the proliferating microalgae produce toxins that affect other organisms in the food web, remains still poorly understood. Here we analyse the role of toxins produced by a microalgal species and affecting its predators, in determining the success of that species as a bloom former. A three-species predator–prey model is used to define a criterion that determines whether a toxic microalga will be able to initiate a bloom in competition against a non-toxic one with higher growth rate. Dominance of the toxic species depends on a critical parameter that defines the degree of feeding selectivity by grazers. The criterion is applied to a particular simplified model and to numerical simulations of a full marine ecosystem model. The results suggest that the release of toxic compounds affecting predators may be a plausible biological factor in allowing the development of HABs.

Remote Sensing Reflectance and Inherent Optical Properties in the Mid-Chesapeake Bay
Authors: Maria Tzortziou, Ajit Subramaniam, Jay R. Herman, Charles L. Gallegos, Patrick J. Neale and Lawrence W. Harding, Jr.
Source: Estuarine, Coastal and Shelf Science, November 13, 2006

Abstract We used an extensive set of bio-optical data to examine the relationships between inherent optical properties and remotely sensed quantities in an optically complex and biologically productive region of the Chesapeake Bay. Field observations showed that the chlorophyll algorithms used by the MODIS (MODerate resolution Imaging Spectroradiometer) ocean color sensor (i.e. Chlor_a, chlor_MODIS, chlor_a_3 products) do not perform accurately in these Case 2 waters. This is because, at high concentrations of chlorophyll, all MODIS algorithms are based on empirical relationships between chlorophyll concentration and blue:green wavelength remote sensing reflectance (Rrs) ratios that do not account for the typically strong blue-wavelength absorption by non-covarying, dissolved and non-algal particulate components. We found stronger correlation between chlorophyll concentration and red:green Rrs ratios (i.e. Rrs(677)/Rrs(554)). Regionally-specific algorithms that are based on the phytoplankton optical properties in the red wavelength region provide a better basis for satellite monitoring of phytoplankton blooms in these Case 2 waters. Our estimates of f/Q (proportionality factor in the relationship between Rrs and the ratio of water backscattering, bb, and absorption, a, coefficients, bb/(a + bb)) were not considerably different from f/Q previously estimated for same measurement geometry but Case 1 waters. Variation in surface bb significantly affected Rrs magnitude across the visible spectrum and was most strongly correlated (R2 = 0.88) with observed variability in Rrs at 670 nm. Surface values of particulate backscattering were strongly correlated with non-algal particulate absorption, anap (R2 = 0.83). These results, along with the measured backscattering fraction and non-algal particulate absorption spectral slope, indicate that suspended non-algal particles with high inorganic content are the major water constituents regulating bb variability in the studied region of the Chesapeake Bay. Remote retrieval of surface anap from Rrs(670) could be used in conjunction with inversion of UV-blue wavelengths to separate contribution by non-algal particles and colored dissolved organic matter to total light absorption, and monitor non-algal suspended particle concentration and distribution in these Case 2 waters.

Responses of the Toxic Cyanobacterium Microcystis Aeruginosa to Iron and Humic Substances
Authors: Alicja Kosakowska^a, , Marcin Nedzi^b and Janusz Pempkowiak^a
Affilliations: ^aInstitute of Oceanology, Polish Academy of Sciences, Powstanców Warszawy 55, 81-712 Sopot, Poland, ^bInstitute of Oceanography, University of Gdansk, Pilsudskiego 46, 81-378 Gdynia, Poland
Source: Plant Physiology and Biochemistry, May 2007, 45(5):365-370
Iron nutrition and Interactions in Plants, XIII International Symposium on Iron Nutrition and Interactions in Plants (ISINIP)

Abstract: Iron is an essential element to marine biota. Different types of dissolved organic matter (DOM), such as humic substances have impacts on the marine coastal waters iron chemistry. The aim of the study was to examine how the presence of humic substances (both aquatic and sedimentary) may affect iron bioavailability to the bloom-forming cyanobacterium Microcystis aeruginosa Kutzing incubated on standard and modified mineral BG-11 media. The final iron concentrations in the growth media ranged from 0.1 to 100 µM. The results demonstrate that both the growth rate and the concentration of chlorophyll a in cultures of M. aeruginosa are limited by insufficient (‹10 µM) Fe concentrations. The addition of aquatic humic substances in the presence of iron in concentrations ‹0.1 µM increased the optical density 25-fold, and the production of chlorophyll a 15-fold as compared with the cultures exposed to iron only at the same concentration. Sedimentary humic acids in the presence of iron at a concentration of 10 µM reduced the growth and production of chlorophyll a by 50% as compared to the cultures exposed to iron only at the same concentration. Possible mechanisms of humic substances – metal ion – alga interactions are discussed. It is suggested that aquatic humic substances could be of great importance in the formation of cyanobacteria blooms.

Satellite Remote Sensing of Harmful Algal Blooms at the University of Miami Center for Oceans and Human Health
Authors: * Minnett, P J, Carvalho, G, Baringer, W, Banzon, V
Affilliations: University of Miami, Meteorology and Physical Oceanography Rosenstiel School of Marine and Atmospheric Science University of Miami 4600 Rickenbacker Causeway, Miami, FL 33149, United States
Source: American Geophysical Union, Summer 2007, 1400h AN: OS23A-04

Abstract: As part of the NSF-NIEHS Center for Oceans and Human Health at the University of Miami, research is being conducted into the remote sensing of ocean color signatures associated with the occurrence of Harmful Algal Blooms (HABs). Data from the MODerate-resolution Imaging Spectroradiometer (MODIS) are down-linked at the University of Miami's Center for Southeastern Tropical Advanced Remote Sensing (CSTARS) and processed in near-real time to produce mapped fields of water leaving radiance in the ocean color bands, derived quantities including inherent optical properties (IOPs) of seawater, chlorophyll concentration, and sea-surface temperature. Images of these fields are available in near-real time on a web-server. The server also provides access to the data files themselves. One of the applications currently being researched using these data is the identification of HABs over the Central West Florida Shelf where blooms of the toxic dinoflagellate Karenia brevis have a nearly annual occurance. Since chlorophyll concentration alone cannot be used as a unique variable to determine algal taxonomy, other spectral features or optical properties must be brought into play to discriminate among different phytoplankton types. A published technique developed for SeaWiFS (Sea-viewing Wide Field-of-view Sensor) to detect K. brevis (based on high concentration of chlorophyll and low particulate backscatter) was transitioned to measurements of Terra MODIS and replicated the results. These were confirmed by comparisons with in situ measurements. This technique is currently being applied to a multi-year time series of remote measurements from the Aqua MODIS and tested against ship-based data.

The University of Miami Center for Oceans and Human Health
Authors: Fleming, L E, Smith, S L, * Minnett, P J
Affiliations: University of Miami, Center for Oceans and Human Health Rosenstiel School of Marine and Atmospheric Science University of Miami 4600 Rickenbacker Causeway Miami, FL 33149-1098, USA, Miami, FL 33149, United States
Source: American Geophysical Union, Summer 2007, OS23A-04

Abstract: Two recent major reports on the health of the oceans in the United States have warned that coastal development and population pressures are responsible for the dramatic degradation of U.S. ocean and coastal environments. The significant consequences of this increased population density, particularly in sub/tropical coastal regions, can be seen in recent weather events: Hurricanes Andrew, Ivan, and Katrina in the US Gulf of Mexico states, and the Tsunami in Southeast Asia in December 2004, all causing significant deaths and destruction. Microbial contamination, man-made chemicals, and a variety of harmful algal blooms and their toxins are increasingly affecting the health of coastal human populations via the seafood supply, as well as the commercial and recreational use of coastal marine waters. At the same time, there has been the realization that the oceans are a source of unexplored biological diversity able to provide medicinal, as well as nutritional, benefits. Therefore, the exploration and preservation of the earth's oceans have significant worldwide public health implications for current and future generations. The NSF/NIEHS Center for Oceans and Human Health Center (COHH) at the University of Miami Rosenstiel School and its collaborators builds on several decades of collaborative and interdisciplinary research, education, and training to address the NIEHS-NSF research initiative in Oceans and Human Health. The COHH focuses on issues relevant to the Southeastern US and Caribbean, as well as global Sub/Tropical areas worldwide, to integrate interdisciplinary research between biomedical and oceanographic scientists. The Center includes three Research Projects: (1) research into the application of toxic algal culture, toxin analysis, remote sensing, oceanography, and genomics to subtropical/tropical Harmful Algal Bloom (HAB) organism and toxin distribution; (2) exploring the interaction between functional genomics and oceanography of the subtropical/tropical HAB organism, Karenia brevis, and its environmental interactions; and (3) exploring the relationship between microbial indicators and human health effects in sub/tropical recreational marine waters. There are three Facilities Cores supporting this research in Genomics, Remote Sensing, and Toxic Algal Culture. To accomplish this research program in subtropical/tropical oceans and human health, the University of Miami Oceans & Human Health Center collaborates with interdisciplinary scientists at Florida International University (FIU), the Centers for Disease Control and Prevention (CDC), the Miami Dade County Dept of Health, the University of Florida, and other institutions, as well as other Oceans and Human Health Centers and researchers.

Use of the FlowCAM for Semi-automated Recognition and Enumeration of Red Tide Cells (Karenia brevis) in Natural Plankton Samples
Authors: Edward J. Buskey and Cammie J. Hyatt
Source: Harmful Algae, December 2006, 5(6): 685-692

Abstracts Early detection is the most effective way to mitigate the effects of harmful algal blooms (HAB). Cell counts based on examination of microplankton samples using settling chambers and visual inspection with an inverted microscope are tedious and time consuming, and counting precision is generally poor at low cell densities. The FlowCAM is a continuous imaging flow cytometer designed to characterize particles in the microplankton size range (20–200 µm diameter). In this study we examined the ability of the FlowCAM to improve routine monitoring protocols for HAB species by automatically recording information on size and fluorescence per cell. This will eliminate the need to examine cells outside the ranges of these measurements for our target species, Karenia brevis. We also tested the ability of image comparison software to match images of cells in mixed assemblages to images of the target species. For simple mixtures of cultured dinoflagellates, the ability of the image matching software to discriminate target cells varied greatly depending on how similar the two species were in size and shape. When target cells were added to natural plankton samples, the image recognition software correctly identified 80–90% of the target cells, but misidentified 20–50% of non-target cells in the size range of the target species. We conclude that the FlowCAM is less tedious and time-consuming than microscopy, allowing for examination of more cells for greater counting precision. The cell recognition software helps reduce the numbers of cells that must be screened, but images must still be examined by a trained operator to identify the HAB species of interest.

2005

Acute symptoms of cyanobacteria toxins
Author: Hoppu, K
Affiliation: Poison Information Centre, Helsinki University Central Hospital, Helsinki, Finland
Source: Journal of Toxicology: Clinical Toxicology. Vol. 43, no. 5, p. 410. 2005.

Abstract: Cyanobacteria, also commonly called blue-green algae are organisms exhibiting a combination of properties found in algae and bacteria. The cyanobacteria provide a wide-ranging contribution to human affairs in everyday life with both beneficial and detrimental features. Abundant growth of cyanobacteria in water reservoirs creates problems for water suppliers. The growth of strains containing toxins is an increasingly common experience in polluted inland water systems all over the world, and also in some coastal waters. Eutrophication, the enhancement of the natural process of biological production in rivers, lakes and reservoirs caused by increases in levels of nutrients, usually phosphorous and nitrogen compounds, can result in visible cyanobacterial or algal blooms. Cyanotoxins are usually contained within cyanobacterial cells and only rarely occur dissolved in water. Cyanotoxins belong to diverse groups of chemicals showing specific toxic mechanisms in vertebrates. Some are strong neurotoxins (anatoxin-a, anatoxin a(s), saxitoxins), others are primarily hepatotoxic (microcystins, nodularin and cylindrospemopsin), yet others (like lipopolysaccharides) appear to cause health effects (such as gastroenteritis) through mechanisms which are not yet well understood. Although experimental toxicological information clearly indicates health hazards for humans, and cyanobacteria occurrence is widespread there are only few documented cases of human illness unequivocally attributed to cyanotoxins. The symptoms attributed to cyanotoxins are not specific, the diagnosis often is not considered, until other etiologies have proved negative and the delay makes it difficult to demonstrate causal relationship to cyanobacteria and cyanotoxins. Epidemiological evidence for adverse human health effects of cyanotoxins includes studies of human populations that have shown symptoms of poisoning attributed to presence of cyanotoxins in drinking water or other sources of water. Gastrointestinal and hepatic illness attributable to cyanobacterial toxins in water supplies have been coincident with either the breakdown of natural cyanobacterial bloom or with the artificial lysis of a bloom leading to release of toxins from decomposing cells.

Cyanobacterial toxins: risk management for health protection
Author: Codd, GA; Morrison, LF; Metcalf, JS
Affiliation: Division of Environmental and Applied Biology, School of Life Sciences, University of Dundee, DD1 4HN, Dundee, UK
Source: Toxicology and Applied Pharmacology Vol. 203, no. 3, pp. 264-272. 15 Mar 2005.

Abstract: This paper reviews the occurrence and properties of cyanobacterial toxins, with reference to the recognition and management of the human health risks which they may present. Mass populations of toxin-producing cyanobacteria in natural and controlled waterbodies include blooms and scums of planktonic species, and mats and biofilms of benthic species. Toxic cyanobacterial populations have been reported in freshwaters in over 45 countries, and in numerous brackish, coastal, and marine environments. The principal toxigenic genera are listed. Known sources of the families of cyanobacterial toxins (hepato-, neuro-, and cytotoxins, irritants, and gastrointestinal toxins) are briefly discussed. Key procedures in the risk management of cyanobacterial toxins and cells are reviewed, including derivations (where sufficient data are available) of tolerable daily intakes (TDIs) and guideline values (GVs) with reference to the toxins in drinking water, and guideline levels for toxigenic cyanobacteria in bathing waters. Uncertainties and some gaps in knowledge are also discussed, including the importance of exposure media (animal and plant foods), in addition to potable and recreational waters. Finally, we present an outline of steps to develop and implement risk management strategies for cyanobacterial cells and toxins in waterbodies, with recent applications and the integration of Hazard Assessment Critical Control Point (HACCP) principles.

Decision-making framework for ecological impacts associated with the accumulation of cyanotoxins (cylindrospermopsin and microcystin), A
Author: White, Susan H; Duivenvoorden, LeoJ; Fabbro, Larelle D
Affiliation: Freshwater Ecology Group, Centre for Environmental Management, Central Queensland University
Source: Lakes & Reservoirs: Research and Management Vol. 10, no. 1, pp. 25-37. Mar 2005.

Abstract: Toxins produced by cyanoprokaryotes are a key issue in aquatic management because of their potential to exert adverse effects on humans and aquatic biota. The information gap regarding bioaccumulation and biomagnification processes associated with cyanotoxins, however, has resulted in inadequacies in the management and maintenance of biological diversity in lakes and reservoirs affected by toxic cyanoprokaryote blooms. This paper examines the potential for, and effects of, bioaccumulation of two common cyanotoxins, Discussed in the context of the challenges associated with understanding and managing toxin accumulation. Based on the characteristics of cyanotoxin bioavailability, exposure and uptake routes, a theoretical, predictive model for cyanotoxin bioaccumulation is proposed. Key concepts include monitoring changes in toxin availability throughout the progression of a toxic bloom and the prediction of ecological effects based on internal tissue concentrations. The model explores the minimum requirements that managers must undertake in order to properly assess bioaccumulation risk in terms of frequency of toxin testing, toxin fraction determination and assessment of aquatic organisms.

Detection of the cyanobacterial hepatotoxins microcystins
Author: McElhiney, J; Lawton, LA
Affiliation: School of Life Sciences, The Robert Gordon University, Scotland
Source: Toxicology and Applied Pharmacology Vol. 203, no. 3, pp. 219-230. 15 Mar 2005.

Abstract: Concern regarding the presence of microcystins in drinking water and their possible contamination in food (e.g., salad vegetables, fish, shellfish) has resulted in the need for reliable methods for the detection and accurate quantification of this class of toxins. Currently, routine analysis of microcystins is most commonly carried out using high-performance liquid chromatography with photodiode array detection (HPLC-PDA), although more sensitive biological assays such as antibody-based ELISAs and protein phosphatase inhibition assays have also proven useful. However, many of these methods have been hindered by the availability of a wide range of purified microcystins. Although over 60 variants have now been reported, only a very small number are commercially available and calibrated standards are not yet obtainable. This has led to the common practice of reporting microcystin-LR equivalence regardless of which variant is present. The increased availability of HPLC with online mass spectral analysis (HPLC-MS) may facilitate more accurate detection of toxin variants but as several microcystins share the same molecular mass, definitive identification can be difficult. A further difficulty in analyzing microcystins is the requirement for sample processing before analysis. Solid phase extraction (SPE) is typically used to enrich environmental concentrations of microcystins, or to eliminate contaminants from complex samples such as animal and plant tissues. Recently, new technologies employing recombinant antibodies and molecularly imprinted polymers have been exploited to develop assays and biosensors for microcystins. These novel detection systems are highly sensitive, often do not require sample processing, and offer a simpler, less expensive alternative to analytical techniques. They have also been successfully employed in solid phase extraction formats for the concentration and clean up of environmental samples before HPLC analysis.

Empirical study of cyanobacterial toxicity along a trophic gradient of lakes
Author: Giani, A; Bird, DF; Prairie, YT; Lawrence, JF
Source: Canadian Journal of Fisheries and Aquatic Sciences Vol. 62, no. 9, pp. 2100-2109. Sep 2005.

Abstract: A series of 22 lakes in southern Quebec spanning a wide trophic range were sampled to develop models of changes in cyanobacterial abundance and toxicity. All lakes contained toxic cyanobacteria, and epilimnetic toxin content, expressed as microcystin equivalents, was best predicted by total nitrogen concentration and total phosphorus concentration (TP). Although phytoplankton biomass increased linearly with increases in TP among lakes, toxigenic biomass increased as greater than the squared power of TP. The only potentially toxigenic genera whose biomass was correlated with microcystin concentration were Microcystis and Anabaena. Surprisingly, the best model for toxic- species biomass was based on epilimnetic nitrogen. The level of the hepatotoxin microcystin per unit biomass in these organisms did not vary markedly among lakes, supporting the idea that environmental factors control the occurrence, but have only a limited effect on the toxicity, of potentially toxic species.

Genetic Variation of the Bloom-Forming Cyanobacterium Microcystis aeruginosa within and among Lakes: Implications for Harmful Algal Blooms
Author: Wilson, Alan E; Sarnelle, Orlando; Neilan, Brett A; Salmon, Tim P; Gehringer, Michelle M; Hay, Mark E
Affiliation: School of Biology, Georgia Institute of Technology,. Department of Fisheries and Wildlife, Natural Resources Building, Michigan State University, School of Biotechnology and Biomolecular Sciences, University of New South Wales
Source: Applied and Environmental Microbiology Vol. 71, no. 10, pp. 6126-6133. Oct 2005.

Abstract: To measure genetic variation within and among populations of the bloom-forming cyanobacterium Microcystis aeruginosa, we surveyed a suite of lakes in the southern peninsula of Michigan that vary in productivity (total phosphorus concentrations of similar to 10 to 100 mu g liter super(-1)). Survival of M. aeruginosa isolates from lakes was relatively low (i.e., mean of 7% and maximum of 30%) and positively related to lake total phosphorus concentration (P = 0.014, r super(2) = 0.407, n = 14). In another study (D. F. Raikow, O. Sarnelle, A. E. Wilson, and S. K. Hamilton, Limnol. Oceanogr. 49:482-487, 2004), survival rates of M. aeruginosa isolates collected from an oligotrophic lake (total phosphorus of similar to 10 mu g liter super(-1) and dissolved inorganic nitrogen:total phosphorus ratio of 12.75) differed among five different medium types (G test, P of ‹0.001), with higher survival (P = 0.003) in low-nutrient media (28 to 37% survival) than in high-nutrient media. Even with the relatively low isolate survivorship that could select against detecting the full range of genetic variation, populations of M. aeruginosa were genetically diverse within and among lakes (by analysis of molecular variance, Phi sub(sc) = 0.412 [ Phi sub(sc) is an F-statistic derivative which evaluates the correlation of haplotypic diversity within populations relative to the haplotypic diversity among all sampled populations], P = 0.001), with most clones being distantly related to clones collected from lakes directly attached to Lake Michigan (a Laurentian Great Lake) and culture collection strains collected from Canada, Scotland, and South Africa. Ninety-one percent of the 53 genetically unique M. aeruginosa clones contained the microcystin toxin gene (mcyA). Genotypes with the toxin gene were found in all lakes, while four lakes harbored both genotypes possessing and genotypes lacking the toxin gene.

Guidance values for microcystins in water and cyanobacterial supplement products (blue-green algal supplements): a reasonable or misguided approach?
Author: Dietrich, D; Hoeger, S
Affiliation: University of Konstanz, Environmental Toxicology, Germany
Source: Toxicology and Applied Pharmacology Vol. 203, no. 3, pp. 273-289. 15 Mar 2005.

Abstract: This article reviews current scientific knowledge on the toxicity and carcinogenicity of microcystins and compares this to the guidance values proposed for microcystins in water by the World Health Organization, and for blue-green algal food supplements by the Oregon State Department of Health. The basis of the risk assessment underlying these guidance values is viewed as being critical due to overt deficiencies in the data used for its generation: (i) use of one microcystin congener only (microcystin-LR), while the other presently known nearly 80 congeners are largely disregarded, (ii) new knowledge regarding potential neuro and renal toxicity of microcystins in humans and (iii) the inadequacies of assessing realistic microcystin exposures in humans and especially in children via blue-green algal food supplements. In reiterating the state-of-the-art toxicology database on microcystins and in the light of new data on the high degree of toxin contamination of algal food supplements, this review clearly demonstrates the need for improved kinetic data of microcystins in humans and for discussion concerning uncertainty factors, which may result in a lowering of the present guidance values and an increased routine control of water bodies and food supplements for toxin contamination. Similar to the approach taken previously by authorities for dioxin or PCB risk assessment, the use of a toxin equivalent approach to the risk assessment of microcystins is proposed.

Hepatotoxic cyanobacterial peptides in Estonian freshwater bodies and inshore marine water
Author: Tanner, R; Kangur, K; Spoof, L; Meriluoto, J
Affiliation: National Institute Chemical Physics and Biophysics, Akadeemia Estonia
Source: Proceedings of the Estonian Academy of Sciences. Biology, Ecology Vol. 54, no. 1, pp. 40-52. 2005.

Abstract: Mass growths of cyanobacteria (blue-green algae), leading to the production of scums and mats, occur sometimes in nutrient-enriched waterbodies throughout the world, including Estonia. This paper shortly summarizes information about cyanobacterial toxins, reports first results of liquid chromatographic-mass spectrometric analyses of cyanobacterial toxins in some waterbodies in Estonia, and attempts to assess possible risk of associated local health problems by drawing some parallels with the situation in neighbouring Finland. The risk of drinking toxin-containing water by the population of Narva in connection with some toxic cyanobacterial bloom in northern Lake Peipsi is outlined. The need for regular monitoring of toxicity of cyanobacterial blooms as well as deeper research of ecological consequences of blooms of toxic cyanobacteria is emphasized in this connection.

Identification of potentially toxic environmental Microcystis by individual and multiple PCR amplification of specific microcystin synthetase gene regions
Author: Ouahid, Youness; Perez-Silva, Gonzalo; Del Campo, Francisca F
Affiliation: Plant Physiology Laboratory, Department of Biology, Universidad Autonoma de Madrid
Source: Environmental Toxicology Vol. 20, no. 3, pp. 235-242. 2005.

Abstract: Reliable cyanotoxin monitoring in water reservoirs is difficult because of, among other reasons, unpredictable changes in cyanobacteria biomass, toxin production, and inadequate sampling frequency. Therefore, it would be useful to identify potentially microcystin-producing strains of cyanobacterial populations in field samples. With this aim, we developed a methodology to distinguish microcystin-producing from non-producing Microcystis strains by amplifying six characteristic segments of the microcystin synthetase mcy cluster, three corresponding to the nonribosomal peptide synthetase, genes mcyA, mcyB, and mcyC, and three to the polyketide synthase, genes mcyD, mcyE, and mcyG. For this purpose five new primer sets were designed and tested using purified DNA, cultured cells, and field colonies as DNA sources. Simultaneous amplification of several genes in multipex PCR reactions was performed in this study. The results obtained showed that: (i) the expected specific amplicons were obtained with all microcystin-producing strains but not with nonproducing strains; (ii) cells could be directly used as DNA templates, 2000 cells being a sufficient number in most cases; (iii) simultaneous amplification of several gene regions is feasible both with cultured cells and with field colonies. Our data support the idea that the presence of various mcy genes in Microcystis could be used as a criterion for ascribing potential toxigenicity to field strains, and the possibility of applying whole-cell assays for the simultaneous amplification of various genes may contribute significantly to simplifying toxigenicity testing.

Investigating the use of zebra mussels, Dreissena polymorpha , as a biomonitoring tool of toxic cyanobacterial blooms
Author: Szprygada, Kristy Ann
Source: Masters Abstracts International Vol. 43, no. 2, p. 491. Apr 2005.

Abstract: Zebra mussels have invaded the United States and out-competed many native unionids for food and space. A series of laboratory feeding experiments were conducted with Chlorella vulgaris (non-toxic) and Microcystis aeruginosa, a microcystin producing cyanobacterium. Mussel tissues were collected from the laboratory feeding experiments, as well as Oneida Lake, Lake Champlain and the Hudson River. Tissues were analyzed for microcystin using a protein phosphatase inhibition assay, high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS). Zebra mussels filtered and ingested both species of algae. Clearance and grazing rates were slower in the presence of the toxic Microcystis . Microcystin accumulation in the zebra mussel tissue was detected in a few of the laboratory and field samples. The glutathione conjugate was not detected by HPLC or LC-MS techniques. Additional research is needed to determine if zebra mussels can be used as biomonitors of toxic cyanobacterial blooms with modification of the analytical techniques.

Investigations into the taxonomy, toxicity and ecology of benthic cyanobacterial accumulations in Myall Lake, Australia
Author: Dasey, M; Ryan, N; Wilson, J; McGregor, G; Fabbro, L; Neilan, BA; Burns, BP; Kankaanpaeae, H; Morrison, LF; Codd, GA; Rissik, D; Bowling, L
Affiliation: NSW Department of Infrastructure, Planning and Natural Resources, Centre for Natural Resources, Australia
Source: Marine & Freshwater Research Vol. 56, no. 1, pp. 45-55. 2005

Abstract: Large benthic accumulations of cyanobacteria occur in sheltered embayments within Myall Lake, New South Wales, Australia. The lake is shallow, with the entire bottom within the euphotic zone, and it is generally considered pristine, having low nutrient concentrations. The accumulations are highly organic and contain a mix of species mainly from the order Chroococcales, with two forms of Aphanothece being dominant. However polymerase chain reaction (PCR) analysis indicates a close similarity to Microcystis flos-aquae. The cells appear to lack aerotopes and form sticky mucilaginous amalgamations, which may enhance their benthic habit. Although Chroococcales also dominate the planktonic cyanobacterial community, the benthic species are seldom, if ever, found entrained within the water column. Some hepatotoxicity was indicated by mouse bioassay, protein phosphatase inhibition assay, enzyme-linked immuno-sorbent assay (ELISA) for microcystins, PCR and by chromatographic evidence for a microcystin. Ecological aspects of the distribution, gross morphology of the organisms and management implications for recreational water-users are discussed.

Method for detecting classes of microcystins by combination of protein phosphatase inhibition assay and ELISA: comparison with LC-MS
Author: Mountfort, D; Holland, P; Sprosen, J
Affiliation: Cawthron Institute, Private Bag 2, Nelson, New Zealand
Source: Toxicon Vol. 45, no. 2, pp. 199-206. Feb 2005.

Abstract: Depending on the class of microcystin the protein phosphatase inhibition assay shows different sensitivities to different classes of toxin. We have determined that the IC sub(50) values obtained from dose-response curves for the inhibition of the enzyme by microcystin LR, nodularin, YR, and RR were 2.2, 1.8, 9 and 175 nM, respectively. When equimolar amounts of these toxins were determined by the ELISA assay with microcystin LR as the standard, the assay showed equivalence in toxin responses. However, when the toxins were determined by the protein phosphatase inhibition assay using microcystin LR as the standard, the ratios of the values determined by PP-2A to ELISA decreased in the order: nodularin (2.23) microcystin LR (1.1)› microcystin YR (0.63)› microcystin RR (0.06). When the ratios for each standard were plotted against the IC sub(50) values, the log-log plot was negative linear, and the lowest value for the IC sub(50) corresponded with the lowest ratio. The differential sensitivity of the PP-2A assay to the various standards was used to establish an indicative toxicity ranking (ITR) where a ranking of 1 (the highest) was assigned to ratios of 0.8 or greater, and 3 (the lowest) to values [precedesorequalto]0.2. The three ranking classes corresponded to toxin equivalence represented by the four standards. The new method allows not only the determination of microcystin toxins in terms of stoichiometry (ELISA) but also in terms of indicative toxicity. The method can be performed using the same instrument (e.g. multiwell fluorimeter with absorbance capability) and offers an advantage to methods presently used to determine microcystins (e.g. ELISA or LC-MS). The former has the propencity to overestimate toxicity because it measures equivalence to microcystin LR and is a stoichiometric measurement and the latter has the disadvantage in that relatively few of the microcystins that occur naturally are available as standards. The new method was applied to the analysis of sample from lakes and streams from temperate locations and to extracts of cyanobacterial mats from ponds and streams in cold temperature locations.

Microcystin Composition of the Cyanobacterium Planktothrix agardhii Changes toward a More Toxic Variant with Increasing Light Intensity, The
Author: Tonk, Linda; Visser, Petra M; Christiansen, Guntram; Dittmann, Elke; Snelder, Eveline OFM; Wiedner, Claudia; Mur, Luuc R; Huisman, Jef
Affiliation: Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, Institute for Biology, Molecular Ecology, Humboldt University of Berlin
Source: Applied and Environmental Microbiology Vol. 71, no. 9, pp. 5177-5181. Sep 2005.

Abstract: The cyanobacterium Planktothrix agardhii, which is dominant in many shallow eutrophic lakes, can produce hepatotoxic microcystins. Currently, more than 70 different microcystin variants have been described, which differ in toxicity. In this study, the effect of photon irradiance on the production of different microcystin variants by P. agardhii was investigated using light-limited turbidostats. Both the amount of the mRNA transcript of the mcyA gene and the total microcystin production rate increased with photon irradiance up to 60 mu mol m super(-2) s super(-1), but they started to decrease with irradiance greater than 100 mu mol m super(-2) s super(-1). The cellular content of total microcystin remained constant, independent of the irradiance. However, of the two main microcystin variants detected in P. agardhii, the microcystin-DeRR content decreased twofold with increased photon irradiance, whereas the microcystin-DeLR content increased threefold. Since microcystin-DeLR is considerably more toxic than microcystin-DeRR, this implies that P. agardhii becomes more toxic at high light intensities.

Occurrence and elimination of cyanobacterial toxins in drinking water treatment plants
Author: Hoeger, SJ; Hitzfeld, BC; Dietrich, DR
Affiliation: Environmental Toxicology, University of Konstanz, Konstanz, Germany
Source: Toxicology and Applied Pharmacology Vol. 203, no. 3, pp. 231-242. 15 Mar 2005.

Abstract: Toxin-producing cyanobacteria (blue-green algae) are abundant in surface waters used as drinking water resources. The toxicity of one group of these toxins, the microcystins, and their presence in surface waters used for drinking water production has prompted the World Health Organization (WHO) to publish a provisional guideline value of 1.0 mu g microcystin (MC)-LR/l drinking water. To verify the efficiency of two different water treatment systems with respect to reduction of cyanobacterial toxins, the concentrations of MC in water samples from surface waters and their associated water treatment plants in Switzerland and Germany were investigated. Toxin concentrations in samples from drinking water treatment plants ranged from below 1.0 mu g MC-LR equiv./l to more than 8.0 mu g/l in raw water and were distinctly below 1.0 mu g/l after treatment. In addition, data to the worldwide occurrence of cyanobacteria in raw and final water of water works and the corresponding guidelines for cyanobacterial toxins in drinking water worldwide are summarized.

Overview of key phytoplankton toxins and their recent occurrence in the North and Baltic Seas
Author: Dahlmann, Erler; Gerdts, Wasmund; Hummert, Hansen P
Affiliation: Institute of Nutrition, University of Jena
Source: Environmental Toxicology Vol. 20, no. 1, pp. 1-17. 2005.

Abstract: The frequency and intensity of harmful algal blooms (HABs) appear to be on the rise globally. There is also evidence of the geographic spreading of toxic strains of these algae. Consequently, methods had to be established and new ones are still needed for the evaluation of possible hazards caused by increased algal toxin production in the marine food chain. Different clinical effects of algae-related poisoning have attracted scientific attention; paralytic shellfish poisoning, diarrhetic shellfish poisoning, and amnesic shellfish poisoning are among the most common. Additionally, cyanobacteria (blue-green algae) in brackish waters often produce neurotoxic and hepatotoxic substances. Bioassays with mice or rats are common methods to determine algal and cyanobacterial toxins. However, biological tests are not really satisfactory because of their low sensitivity. In addition, there is growing public opposition to animal testing. Therefore, there has been increasing effort to determine algal toxins by chemical methods. Plankton samples from different European marine and brackish waters were taken during research cruises and analyzed on board directly. The ship routes covered marine areas in the northwest Atlantic, Orkney Islands, east coast of Scotland, and the North and Baltic seas. The first results on the occurrence and frequency of harmful algal species were obtained in 1997 and 1998. During the 2000 cruise an HPLC/MS coupling was established on board, and algal toxins were measured directly after extraction of the plankton samples. In contrast to earlier cruises, the sampling areas were changed in 2000 to focusing on coastal zones. The occurrence of toxic algae in these areas was compared to toxin formation during HABs in the open sea. It was found that the toxicity of the algal blooms depended on the prevailing local conditions. This observation was also confirmed by monitoring cyanobacterial blooms in the Baltic Sea. Optimal weather conditions, for example, during the summers of 1997 and 2003, favored blooms of cyanobacteria in all regions of the Baltic. The dominant species regarding the HABs in the Baltic was Nodularia spumigena. However, in addition to high concentrations of Nodularia spumigena in coastal zones, other blue-green algae are involved in bloom formation, with changes in plankton communities influencing both toxin profiles and toxicity.

Quantification of Toxic Microcystis spp. during the 2003 and 2004 Blooms in Western Lake Erie using Quantitative Real-Time PCR
Author: Rinta-Kanto, JM; Ouellette, AJA; Boyer, GL; Twiss, MR; Bridgeman, TB; Wilhelm, SW
Affiliation: Department of Microbiology, The University of Tennessee
Source: Environmental Science & Technology Vol. 39, no. 11, pp. 4198-4205. 1 Jun 2005.

Abstract: In August of 2003 and August of 2004, blooms of potentially toxic cyanobacteria Microcystis spp. persisted in western Lake Erie. Samples collected from the bloom were analyzed for the cyanobacterial toxin microcystin and the presence of Microcystis spp. cells. Estimates of microcystin toxicity exceeding 1 mu g L super(-1) (microcystin-LR activity equivalents), the safety limit set by the World Health Organization, were found from the samples in both 2003 and 2004. The presence of Microcystis spp. in water samples was confirmed through standard polymerase chain reaction (PCR) using a combination of four primer sets. Quantification of Microcystis was accomplished by a real-time PCR assay utilizing specific primer-Taq-man probe sets targeted on a conserved, Microcystis-specific 16S rDNA fragment and a microcystin toxin synthetase gene mcyD. This approach allowed us to specifically study the distribution and abundance of toxic Microcystis in the lake in contrast to previous studies that have assessed Microcystis populations with less refined methods. On the basis of quantification by quantitative real-time PCR analysis, the total abundance of Microcystis cells in the bloom area varied from 4 x 10 super(8) to 2 x 10 super(3) cells L super(-1). The results of this study provide novel insight regarding the distribution and abundance of Microcystis spp. in the western basin of Lake Erie, a region plagued in recent years by large-scale (›20 km super(2)) blooms. Our results suggest that the Maumee River and Bay may serve as a source for Microcystis to western and central Lake Erie.

Seasonal changes in composition of the cyanobacterial community and the occurrence of hepatotoxic blooms in the eastern townships, Quebec, Canada
Author: Rolland, A; Bird, DF; Giani, A
Affiliation: Departement des Sciences Biologiques, Universite Du Quebec A Montreal
Source: Journal of Plankton Research Vol. 27, no. 7, pp. 683-694. Jul 2005.

Abstract: Four eutrophic lakes in the eastern townships (Quebec, Canada) were sampled on a biweekly basis between May and October 2001 to examine seasonal changes, and to study the role of taxonomic and environmental factors in cyanobacterial toxin production. Microcystin-LR (MC-LR) equivalent content was determined using a protein phosphatase inhibition assay on extracts of lyophilized plankton. Three of the lakes showed a similar pattern of maximum water column toxicity in late summer, while in the fourth, toxicity was highest in spring and then declined over the year. Variations in water toxicity level could be attributed to the abundance of two potentially toxigenic genera, Microcystis and Anabaena. rogen concentration (TN) and the biomass of these two genera. Microcystis and Anabaena genera appeared to be similarly toxic in all lakes. Increased water column stability, higher light extinction coefficient and a lack of dissolved nutrients were all associated with increased total biomass of toxigenic cyanobacterial genera.

Selective control of toxic Microcystis water blooms using lysine and malonic acid: An enclosure experiment
Author: Kaya, Kunimitsu; Liu, Yong-Ding; Shen, Yin-Wu; Xiao, Bang-Ding; Sano, Tomoharu
Affiliation: Graduate School of Environmental Studies, Tohoku University
Source: Environmental Toxicology Vol. 20, no. 2, pp. 170-178. 2005

Abstract: Three enclosures (10 X 10 X 1.5-1.3 m in depth) were set beside Dianch Lake, Kunming, People's Republic of China, for the period from July 28 to August 26, 2002. The enclosures were filled with cyanobacterial (Microcystis aeruginosa) water bloom-containing lake water. Lake sediment that contained macrophytes and water chestnut seeds was spread over the entire bottom of each enclosure. Initially, 10 g/m super(2) of lysine was sprayed in Enclosure B, and 10 g/m super(2) each of lysine and malonic acid were sprayed together in Enclosure C. Enclosure A remained untreated and was used as a control. The concentrations of lysine, malonic acid, chlorophyll a, and microcystin as well as the cell numbers of phytoplankton such as cyanobacteria, diatom, and euglena were monitored. On day 1 of the treatment, formation of cyanobacterial blooms almost ceased in Enclosures B and C, although Microcystis cells in the control still formed blooms. On day 7 Microcystis cells in Enclosure B that had been treated with lysine started growing again, whereas growth was not observed in Microcystis cells in Enclosure C, which had been treated with lysine and malonic acid. On day 28 the surface of Enclosure B was covered with water chestnut (Trapa spp.) and the Microcystis blooms again increased. In contrast, growth of macrophytes (Myriophllum spicatum and Potamogeton crispus) was observed in Enclosure C; however, no cyanobacterial blooms were observed. Lysine and malonic acid had completely decomposed. The microcystin concentration on day 28 decreased to 25% of the initial value, and the pH shifted from the initial value of 9.2 to 7.8. We concluded that combined treatment with lysine and malonic acid selectively controlled toxic Microcystis water blooms and induced the growth of macrophytes.

Simple colorimetric method to detect biological evidence of human exposure to microcystins, A
Author: Hilborn, Elizabeth D; Carmichael, Wayne W; Yuan, Moucun; Azevedo, Sandra MFO
Affiliation: United States Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory
Source: Toxicon Vol. 46, no. 2, pp. 218-221. Aug 2005.

Abstract: Toxic cyanobacteria are contaminants of surface waters worldwide. Microcystins are some of the most commonly detected cyanotoxins. Biological evidence of human exposure may be difficult to obtain due to limitations associated with cost, laboratory capacity, analytic support, and expertise. We investigated the application of an enzyme-linked immunosorbant assay (ELISA) to detect microcystins in human serum. We analyzed ten serum samples collected from dialysis patients who were known to be exposed to a mixture of microcystins during a 1996 outbreak in Brazil. We applied a commercially available ELISA method to detect microcystins in serum, and we compared the ELISA results to a more specific method, liquid chromatography/mass spectrometry (LC/MS) that was also used to detect microcystins in serum. The Spearman correlation coefficient was calculated using serum microcystin concentrations in split samples obtained by the two methods. Serum microcystin concentrations were similar, and we found good correlation of microcystin concentrations between the two methods. The ELISA detected total microcystins, median=19.9 ng/ml; LC/MS detected microcystin-LR equivalents, median=21.2 ng/ml; Spearman r=0.96, p‹0.0001. We found that ELISA is a simple, accessible method to screen human serum for evidence of microcystin exposure.

2004

Assimilation and depuration of microcystin-LR by the zebra mussel, Dreissena polymorpha
Author: Pires, LMDionisio; Karlsson, KM; Meriluoto, JAO; Kardinaal, E; Visser, PM;
Affiliation: Department of Foodweb Studies, Centre for Limnology, Netherlands
Source: Aquatic Toxicology Vol. 69, no. 4, pp. 385-396. 20 Sep 2004

Abstract: Zebra mussels (Dreissena polymorpha) are an important component of the foodweb of shallow lakes in the Netherlands, amongst others in Lake IJsselmeer, an international important wetland. Large numbers of ducks feed on these mussels in autumn and winter. The mussels are filter feeders and are exposed to high densities of cyanobacteria in summer and autumn. Mussels and cyanobacteria both thrive in Lake IJsselmeer. Apparently the mussels are somehow protected against accumulation of harmful quantities of cyanobacterial toxins. In this study, we investigated the assimilation of the cyanobacterial toxin microcystin-LR (MC-LR) in zebra mussels when fed the toxic cyanobacterium Microcystis aeruginosa as sole food or in a mixture with the eustigmatophyte Nannochloropsis limnetica. After 3 weeks of assimilation we studied the depuration of MC-LR during 3 weeks when the food of the mussels was free of cyanobacteria. These assimilation/depuration experiments were combined with grazing experiments, using the same food treatments. Microcystins were analyzed using liquid chromatography-mass spectrometry (LC-MS); in addition, covalently bound MC were analyzed using the MMPB method. The mussels showed higher clearance rates on Microcystis than on Nannochloropsis. No selective rejection of either phytoplankton species was observed in the excretion products of the mussels. Zebra mussels fed Microcystis as single food, assimilated microcystin-LR relatively fast, and after 1 week the maximum value of free unbound microcystin assimilation (ca. 11 mu ggDW super(-) super(1)) was attained. For mussels, fed with the mixed food, a maximum of only 3.9 mu ggDW super(-) super(1) was recorded after 3 weeks. Covalently bound MC never reached high values, with a maximum of ~62% of free MC in the 2nd week of the experiment. In the depuration period microcystin decreased rapidly to low values and after 3 weeks only very low amounts of microcystin were detectable.The amount of toxin that accumulated in the mussels would appear to be high enough to cause (liver) damage in diving ducks. However, death by exposure to microcystin seems unlikely. Mussels seem efficient in minimizing the assimilation of microcystin. If it were not for this, mass mortalities of ducks in shallow lakes in the Netherlands would presumably occur on a much more widespread scale than is currently observed.

Comparison of 17 biotests for detection of cyanobacterial toxicity
Author: Marsalek, Blahoslav; Blaha, Ludek
Affiliation: Institute of Botany, Czech Academy of Sciences
Source: Environmental Toxicology Vol. 19, no. 4, pp. 310-317. 2004.

Abstract: The aim of the present study was to compare the sensitivity of 17 acute bioassays of cyanobacterial toxicity by assessment of crude extracts of three cyanobacterial samples (all dominated by Microcystis sp. but substantially differing in microcystin-LR content). Toxicity of the fractions prepared by solid-phase extraction (SPE) for microcystins was also determined. The most sensitive bioassay was the 24-h test with crustacean Thamnocephalus platyurus, which elicited high lethality in the samples and also in fractions without microcystins. The fruit fly Drosophila melanogaster, protozoans Spirostomum ambiguum and Tetrahymena termophyla, and the crustacean Daphnia pulex formed the second group of sensitive bioassays. Good selective toxicity response to microcystins also was observed in the weakly sensitive biotests with the oligochaete Tubifex tubifex and the rotifer Brachionus calyciflorus. Preconcentration of microcystins by SPE substantially decreased variation of the results in bioassays and improved the discriminating potential of most assays employed.

Effects of Nitrogen Forms on the Production of Cyanobacterial Toxin Microcystin-LR by an Isolated Microcystis aeruginosa
Author: Yan, Hai; Pan, Gang; Zou, Hua; Song, Lirong; Zhang, Mingming
Affiliation: Research Center for Eco-environmental Sciences, Chinese Academy of Sciences
Source: Journal of Environmental Science and Health, Part A: Toxic/Hazardous Substances & Environmental Engineering Vol. A39, no. 11-12, pp. 2993-3003. 2004.

Abstract: A cyanobacterial strain, which produced high content of microcystin-LR (MC-LR) but no microcystin-RR (MC-RR), was isolated from the hypertrophic Dianchi Lake in China and identified as Microcystis aeruginosa DC-1. Effects of nitrogen containing chemicals and trace elements on the growth and the production of MC-LR by this strain were studied. In the presence of bicine, compared with urea and ammonium, nitrate greatly promoted the growth and the production of MC-LR. However, leucine and arginine, which were the constitutional components in the molecular structure of MC-LR or RR, inhibited the production of MC-LR. Iron and silicon up to 10 mg/L had little effects on the growth of M. aeruginosa DC-1, but the production of MC-LR was apparently enhanced. Under all conditions studied here, only MC-LR but no RR was detected within the cells of M. aeruginosa DC-1. Thus, chemical forms of nitrogen, rather than the usually concerned the total nitrogen, and trace elements played important roles in the production of MC toxins during cyanobacterial blooms.

Environmental factors influencing microcystin distribution and concentration in the Midwestern United States
Author: Graham, JL; Jones, JR; Jones, SB; Downing, JA; Clevenger, TE
Affiliation: Department of Fisheries and Wildlife Sciences, University of Missouri
Source: Water Research Vol. 38, no. 20, pp. 4395-4404. Dec 2004.

Abstract: During May-September 2000-2001, physicochemical data were collected from 241 lakes in Missouri, Iowa, northeastern Kansas, and southern Minnesota U.S.A. to determine the environmental variables associated with high concentrations of the cyanobacterial hepatotoxin microcystin (MC). The study region represents a south-north latitudinal gradient in increasing trophic status, with total phosphorus (TP) and total nitrogen (TN) values ranging between 2-995 and 90- 15870 mu g/L, respectively. Particulate MC values, measured by ELISA, ranged from undetectable to 4500 ng/L and increased with increasing latitude. Despite latitudinal trends, environmental variables explained ‹50% of the variation in MC values. Inspection of MC-TN and MC-Secchi bivariate plots revealed distinctly nonlinear trends, suggesting optima for maximum MC values. Nonlinear interval maxima regression indicated that MC-TN maxima were characterized by a unimodal curve, with maximal (›2000 ng/L) MC values occurring between 1500 and 4000 mu g/L TN. Above 8000 mu g/L TN all MC values were ‹150 ng/L. MC-Secchi maxima were characterized by exponential decline, with maximal MC values occurring at Secchi depths ‹2.5 m. The development of empirical relationships between environmental variables and MC values is critical to effective lake management and minimization of human health risks associated with the toxin. This study indicates MC values are linked to the physicochemical environment; however, the relationships are not traditional linear models.

Identification of an Na super(+)-Dependent Transporter Associated with Saxitoxin-Producing Strains of the Cyanobacterium Anabaena circinalis
Author: Pomati, Francesco; Burns, Brendan P; Neilan, Brett A
Affiliation: Cyanobacteria and Astrobiology Research Laboratory, School of Biotechnology and Biomolecular Sciences, The University of New South Wales
Source: Applied and Environmental Microbiology Vol. 70, no. 8, pp. 4711-4719. Aug 2004.

Abstract: Blooms of the freshwater cyanobacterium Anabaena circinalis are recognized as an important health risk worldwide due to the production of a range of toxins such as saxitoxin (STX) and its derivatives. In this study we used HIP1 octameric-palindrome repeated-sequence PCR to compare the genomic structure of phylogenetically similar Australian isolates of A. circinalis. STX-producing and nontoxic cyanobacterial strains showed different HIP1 (highly iterated octameric palindrome 1) DNA patterns, and characteristic interrepeat amplicons for each group were identified. Suppression subtractive hybridization (SSH) was performed using HIP1 PCR-generated libraries to further identify toxic-strain-specific genes. An STX-producing strain and a nontoxic strain of A. circinalis were chosen as testers in two distinct experiments. The two categories of SSH putative tester-specific sequences were characterized by different families of encoded proteins that may be representative of the differences in metabolism between STX-producing and nontoxic A. circinalis strains. DNA-microarray hybridization and genomic screening revealed a toxic-strain-specific HIP1 fragment coding for a putative Na super(+)-dependent transporter. Analysis of this gene demonstrated analogy to the mrpF gene of Bacillus subtilis, whose encoded protein is involved in Na super(+)-specific pH homeostasis. The application of this gene as a molecular probe in laboratory and environmental screening for STX- producing A. circinalis strains was demonstrated. The possible role of this putative Na super(+)-dependent transporter in the toxic cyanobacterial phenotype is also discussed, in light of recent physiological studies of STX-producing cyanobacteria.

Microcystin-producing blooms-a serious global public health issue
Author: de Figueiredo, DR; Azeiteiro, UM; Esteves, SM; Goncalves, FJ;
Affiliation: Departamento de Biologia, Universidade de Aveiro
Source: Ecotoxicology and Environmental Safety Vol. 59, no. 2, pp. 151-163. Oct 2004.

Abstract: The investigation on microcystin topics is increasing due to the related ecological and public health risks. Recent investigation confirms a gap in establishing global patterns relating a particular environment to the bloom occurrence of a species and the production of certain microcystin variants. All the results concerning the environmental effects on the microcystin synthesis of one species must be checked in the light of genome diversity. Thus, the poisoning risks of a bloom depend on the strain causing toxicity. To be more effective, specific water treatment methods are required for blooms of different microcystin producing species (such as colonial and filamentous cyanobacteria found in stratified and unstratified water bodies, respectively). With the increasing number of new microcystin variants discovered, the development of new rapid, inexpensive and sensitive enough monitoring methods to promptly screen simultaneously a great diversity of toxins and also check their toxic effects is becoming necessary.

Phormidium and Musty odor in a reservoir
Author: Kudo, Katsuhiro; Kawakami, Tomoyuki; Yamada, Tadashi
Affiliation: Research and Training Institute, Japan Water Agency
Source: Journal of the Japan Society of Hydrology & Water Resources Vol. 17, no. 4, pp. 331-342. 2004.

Abstract: Eutrophication in reservoirs is one of worldwide environmental issues. Eutrophication causes deterioration of landscape due to blooming of blue green algae and red tide, foul smell of drinking water and deterioration of water quality due to water-bloom. In particular, the problem of musty odor of tap water is serious. Severe problems of musty odor occurred since 1984 to 1990 in four dam reservoirs, which are managed by Water Resources Development Public Corporation. The cause of musty odor was 2-MIB derived from Phormidium. The water quality in four reservoirs was observed around 2 times a week for the period when Phormidium grew in those reservoirs. As a result, we obtained valuable information on the relation between 2-MIB and musty odor, and found that most of the produced 2-MIB are dissolved in the water.

Primary research of the microcystin's fate in natural aquatic system
Author: Zhang, W-H; Song, L-R; Xu, X-Q; Liu, Y-D; Zhang, X-H
Affiliation: Research Center for Environmental Engineering & Management, Shenzhen Graduate School of Tsinghua University
Source: Resources and Environment in the Yangtze Basin Vol. 13, no. 1, pp. 84-88. 2004.

Abstract: Microcystins are hepatotoxin released by harmful toxic cyanobacterial bloom, are the potential risk factor of natural environment and human health. MC-LR has been listed as the special examining item in the newly published Environmental Quality Standard for the surface water. The paper investigated the seasonal variation of microcystin concentrations in lake Dianchi, where serious bloom has occurred in recent years. The concentration of microcystins has a range of 0.17-0.82 mu g/L, which is far less than the amount in the cyanobacteria mass. The fate of microcystin in the lake was put forward on the base of absorption, photodegradation, and biodegradation experiments in site or in the laboratory. The results showed that the photodegradation was the main approach of the microcystins elimination, while biodegradation, bioaccumulation, and adsorption had also contribution in reducing the concentration of microcystins in water.

Review of Microcystin Algal Toxin Treatment and Microcystin Levels in 33 North American Surface Water Supplies
Source: 2004 AWWA Annual Conference Proceedings

Abstract: Cyanobacteria, also called blue-green algae, are photosynthetic bacteria found primarily in surface waters. Eutrophic surface waters are at highest risk for cyanobacterial blooms; these include ponds, lakes, and water treatment plant reservoirs under the influence of extraneous nutrients from agricultural runoff or sewage. Cyanobacteria are of interest to the water treatment community because they produce compounds which are toxic to humans and animals. This work reviews the current state of water treatment for cyanotoxins and presents the results of a summer 2003 survey plants are made in view of the treatment options and extent of toxin contamination. A commercially available immunoassay kit detected microcystins in 87% of 40fold concentrated raw samples and 30% of concentrated effluent samples. The remainder in each case was below the enhanced assay detection limit of 0.031 ppb for raw samples and 0.080 ppb for effluent samples. Raw water microcystin levels, expressed as the mean of six measurements, can be considered background when compared to the I ppb World Health Organization (WHO) guideline. However, two raw water sources consistently showed high microcystin concentrations. One of these was inactive, and the other was removed from service during testing due to odor problems. Plant effluent levels, expressed as the mean of two measurements, were only detectable at five of 28 sampling sites.

Toxicity of microcystin from cyanobacteria growing in a source of drinking water
Author: Majsterek, I; Sicinska, P; Tarczynska, M; Zalewski, M; Walter, Z
Affiliation: Department of Molecular Genetics, University of Lodz
Source: Comparative Biochemistry and Physiology, Part C: Toxicology & Pharmacology Vol. 139, no. 1-3, pp. 175-179. Oct 2004.

Abstract: fMicrocystin-LR (MC-LR) is a cyanobacterial heptapeptide that presents acute and chronic hazards to animal and human health. The morphological changes in mitochondria are the primary effect induced by MC-LR leading to cell death. We investigated the toxicity of cyanobacterial microcystin-containing extract (CEM) on the respiratory complex of mammalian mitochondria from Bos taurus. Cyanobacterial blooms of Microcystis aeruginosa were harvested from Sulejow Reservoir, a source of drinking water in central Poland. The concentration of microcystin-LR (MC-LR super(CEM)) in CEM extract was determined by high-performance liquid chromatography (HPLC). Commercially available microcystin-LR (Sigma) was used as a standard (MC-LR ); both standard and CEM extract were incubated with mitochondria in different doses and time of exposure. MC-RL super(CEM) at 1 nM, maximal acceptable dose of microcystin (WHO) in drinking water, provoked activation of cytochrome c oxidase complex in mitochondria. We suggest that it might be considered as a defensive signal of mitochondria against low concentration of a toxic compound. In contrast 1 iM MC-RL super(CME) inhibited the activity of mitochondrial oxidase complex much stronger than the same concentration of standard MC-RL (58% vs. 87% of control activity, P‹0.05), and this may cause a similar effect to long-term consumption of water. In conclusion, we affirm that CEM extract is highly toxic, and mitochondria could be used as an indicator of this toxicity in vivo, especially during long-term consumption of water from reservoirs where microcystin is produced.

Uptake kinetics and immunotoxic effects of microcystin-LR in human and chicken peripheral blood lymphocytes in vitro, The
Author: Lankoff, A; Carmichael, WW; Grasman, KA; Yuan, M
Affiliation: Department of Radiobiology and Immunology, Institute of Biology, Pedagogical University, Poland
Source: Toxicology Vol. 204, no. 1, pp. 23-40. Nov 2004

Abstract: Microcystin-LR is a cyanobacterial heptapeptide that presents acute and chronic hazards to animal and human health. We investigated the influence of this toxin on human and chicken immune system modulation in vitro. Peripheral blood lymphocytes were treated with microcystin-LR at environmentally relevant doses of 1, 10 and 25 as apoptosis and necrosis were determined in human and chicken samples. IL-2 and IL-6 production by human lymphocytes also was measured. In addition, uptake kinetics of microcystin-LR into human and chicken peripheral blood lymphocytes were calculated by Liquid Chromatography (LS) /Mass Spectrometry (MS) analysis. At the highest dose microcystin-LR decreased T-cell proliferation and all doses of microcystin-LR inhibited B-cell proliferation. The frequency of apoptotic and necrotic cells increased in a dose and time-dependent manner. Human lymphocytes responded to stimulation with microcystin-LR by increased production of IL-6 and decreased production of IL-2. Human lymphocytes were able to uptake from 0.014 to 1.663 mu g/ml and chicken lymphocytes from 0.035 to 1.733 mu g/ml of the microcystin-LR added to the cultures, depending on the treatment time and dose. In conclusion, microcystin-LR acted as an immunomodulator in cytokine production and down-regulated lymphocyte functions by induction of apoptosis and necrosis. However, further studies dealing with the influence of microcystin-LR on expression cytokine genes and transcription factors are necessary to confirm these hypotheses.

Water treatment options for dissolved cyanotoxins
Author: Newcombe, G; Nicholson, B
Affiliation: Australian Water Quality Centre, a partner in the CRC for Water Quality and Treatment, Australia
Source: Aqua - Journal of Water Supply: Research and Technology Vol. 53, no. 4, pp. 227-239. Jun 2004.

Abstract: When treating water subject to a cyanobacterial bloom the first priority should be removal of intact cells using separation techniques such as coagulation or membrane filtration. Chlorination and ozonation are effective for the destruction of residual dissolved microcystins and cylindrospermopsin. Anatoxin-a can be effectively removed using ozone, although chlorine is relatively ineffective. Oxidation techniques do not appear to be the best method for the treatment of saxitoxins under normal treatment plant operating conditions. Powdered activated carbon can be effective for the removal of all toxins, except, perhaps, microcystin LA, provided the appropriate carbon and the correct dose is applied. Granular activated carbon filters show a limited lifetime for the adsorption of most microcontaminants, including cyanotoxins. The biodegradation of cyanotoxins across GAC filters shows great potential as a treatment process.

2003

Biotoxins in freshwaters of Greece as a hazard: The case of Microcystins.
Author: Vardaka, E; Gkelis, S; Moustaka, M; Lanaras, T
Affiliation: Department of Botany, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
Source: 7th Hellenic Symposium on Oceanography and Fisheries. Chersonissos, Greece, 6-9 May 2003.

Abstract: Microcystins (MCs) are a group of hepatotoxic cyclic heptapeptides produced by several genera of cyanobacteria. Exposure of animals and humans to these toxins has been related worldwide to episodes of illness and death via drinking water and recreationally used water. MCs were first reported in Greek freshwaters in 1987. MC-LR was identified as the major MC in waterbloom samples. More recently, the occurrence of MC-LR was studied from 1994 to 1997 in Lake Kastoria. MC-LR concentration values were maximal in September and October and correlated with the biovolume of Microcystis species and abiotic factors. In 1999 to 2001 a total of 34 freshwaters of mainland Greece (22 natural lakes and 12 dams) were investigated for the occurrence of MCs. MCs were detected by HPLC in all waterbloom samples tested. The MCs identified were MC-LR, [D-Asp super( 3 )] MC-LR, MC-RR, [Dha super( 7 )]MC-RR, MC-YR and MC-LA. The total MC concentrations ranged from 40 to 2400 mu g g super( -1 ) dry weight waterbloom. In samples with low cyanobacterial biovolume (‹1 mm super( -3 ) L super( -1 )) MCs were detected by PP1 assay and ELISA. The presence of MCs in Greek freshwaters tested is a potential hazard for humans and animals when elevated MC concentrations prevail in the water (›1 mu g L super( -1 ) for MC-LR). There is an obvious need for biomonitoring and if necessary appropriate action to protect water quality and human health.

Depth profiles of cyanobacterial hepatotoxins (microcystins) in three Turkish freshwater lakes
Author: Albay, M; Akcaalan, R; Tufekci, H; Metcalf, JS; Beattie, KA; Codd, GA
Affiliation: University of Istanbul, Faculty of Fisheries, Ordu Cad. No: 200 34470 Laleli, Istanbul, Turkey
Source: Hydrobiologia [Hydrobiologia]. Vol. 505, no. 1-3, pp. 89-95. Sep 2003.

Abstract: The Turkish freshwater lakes, Sapanca, Iznik and Taskisi (Calticak) have been enriched with nutrients from agriculture and domestic sources for many years. A major bloom of cyanobacteria (blue-green algae) in Lake Sapanca was recorded in May 1997, closely followed by a fish kill. Investigations were subsequently made on the cyanobacteria and water quality of the lakes, including analysis for cyanobacterial hepatotoxins (microcystins) in the filtered particulate fraction. Samples, taken from the beginning of May to end of August 1998, were ana lysed for microcystins by high-performance liquid chromatography with photodiode array detection (HPLC-PDA), protein phosphatase inhibition assay (PPIA) and an enzyme-linked immunosorbent assay (ELISA). No microcystins were detected in the water column in Lake Sapanca above 10 m, but toxins were found in filtered cyanobacterial samples from 20 m depth at a concentration of 3.65 mu g l super(-1) microcystin-LR equivalents. Ninety percent of the microcystin pool detected in L. Sapanca was found between depths of 15 and 25 m. The principal microcystin detected by HPLC-PDA was similar to microcystin-RR. Two unidentified microcystin variants were found in Lake Taskisi surface samples at a concentration of 2.43 mu g l super(-1) microcystin-LR equivalents in the filtered cyanobacterial cell fraction. Although 10 water samples (10 x 5 l) were taken from Lake Iznik (surface to 20 m, 5 m intervals), no microcystins were detected by HPLC-PDA (limit of detection 10 ng). The depth at which microcystins were detected in L. Sapanca coincided with the draw-off depth for the drinking water supply for the city of Sakarya.

New microcystin concerns in the lower Great Lakes.
Author: Murphy, TP; Irvine, K; Guo, J; Davies, J; Murkin, H; Charlton, M; Watson, SB
Affiliation National Water Research Institute
Source: Theme issue -- Drinking water: from source to tap. Vol. 38, no. 1, pp. 127-140. 2003.

Abstract: Water samples were collected in the summer of 2001 for microcystin analysis, nutrients and algal enumeration from Hamilton Harbour (Lake Ontario), Wendt Beach (Lake Erie) and Presque Isle (Lake Erie). Microcystin concentrations varied largely and were present at acute toxicity levels only in some wind-concentrated scums of blue-green algae in Hamilton Harbour. In Hamilton Harbour, microcystin-RR was the main microcystin with microcystin-YR and -LR also present. The two samples of August 17 and September 7, taken during the peak of the cyanobacterial bloom, contained 60 and 400 upsilon g/L, respectively. A few dying birds were seen in the Hamilton scums. The concentrations of microcystins at the Lake Erie sites were less than 1 upsilon g/L, yet dead birds were common. The major limitation with this approach is that current analysis methods are unable to measure covalently bound micro-cystins, the form that is assimilated into the food chain.

Toxin production of cyanobacteria is increased by exposure to zooplankton
Author: Jang, M; Ha, K; Joo, G*; Takamura, N
Affiliation: Department of Biology, Pusan National University, Busan, South Korea
Source: Freshwater Biology Vol. 48, no. 9, pp. 1540-1550. Sep 2003

Abstract: Cyanobacterial toxin production in response to direct and indirect zooplankton feeding activity was examined using four strains of Microcystis aeruginosa, of which three were previously reported to be toxic to zooplankton and one non-toxic. Direct (Microcystis cultured with zooplankton) and indirect effects (Microcystis cultured with filtered zooplankton culture media, ZCMF) were tested for the zooplankton species, Moina macrocopa, Daphnia magna or D. pulex.With direct exposure to zooplankton, increased mass-specific microcystin productions occurred in all Microcystis strains, with mean microcystin concentrations up to five times greater (61.5-177.3 mu g g super(-1) dry cell) than the controls.With indirect exposure, mass-specific microcystin production increased over controls in three strains of M. aeruginosa. Mean maximum concentrations of microcystin during the experiment were 92.6-125.7 mu g g super(-1) dry cell.These results suggest that several strains of Microcystis aeruginosa increased toxin production in response to direct and indirect exposure to herbivorous zooplankton of several species, and support the hypothesis that this response is an induced defence mediated by the release of info-chemicals from zooplankton.

2002

Blue green algal (cyanobacterial) toxins, surface drinking water, and liver cancer in Florida
Author: Fleming, LE; Rivero, C; Burns, J; Williams, C; Bean, JA; Shea, KA; Stinn, J
Affiliation: NIEHS Marine and Freshwater Biomedical Sciences Center, University of Miami Rosenstiel School of Marine and Atmospheric Studies, Miami, FL, USA
Source: Harmful Algae Vol. 1, no. 2, pp. 157-168. Jun 2002.

Abstract: The blue green algae or cyanobacteria represent a diverse group of organisms that produce potent natural toxins. There have been case reports of severe morbidity and mortality in domestic animals through drinking water contaminated by these toxins. Microcystins, in particular, have been associated with acute liver damage and possibly liver cancer in laboratory animals. Although, there has been little epidemiologic research on toxin effects in humans, a study by Yu (1995) found an association between primary liver cancer and surface water. Surface water drinking supplies are particularly vulnerable to the growth of these organisms; current US drinking water treatment practices do not monitor or actively treat for blue green algal toxins including the microcystins. After a monitoring survey in Florida found organisms and microcystins (among other cyanobacterial toxins) in surface water drinking sources, a pilot ecological study was performed using a Geographic Information System (GIS) to evaluate the risk of primary hepatocellular carcinoma (HCC) and proximity to a surface water treatment plant at cancer diagnosis. The study linked all HCC cancers diagnosed in Florida from 1981 to 1998 with environmental databases. A significantly increased risk for HCC with residence within the service area of a surface water treatment plant was found compared to persons living in areas contiguous to the surface water treatment plants. However, this increased risk was not seen in comparison to persons living in randomly selected ground water treatment service areas or compared to the Florida cumulative incidence rate for the study period, using various comparison and GIS methodologies. Furthermore, these findings must be interpreted in light of significant issues of latency, high population mobility, and the lack of individual exposure information. Nevertheless, the issue of acute and chronic human health effects associated with the consumption of surface waters possibly contaminated by blue green algal toxins merits further investigation.

Cyanobacterial Harmful Algal Blooms (CyanoHABs): Developing a Public Health Response
Author: Backer, LC
Affiliation: National Center for Environmental Health, 1600 Clifton Rd., NE, MS E-23, Atlanta, GA 30333, USA
Source: Lake and Reservoir Management Vol. 18, no. 1, pp. 20-31. Mar 2002.

Abstract: Cyanobacteria, or blue-green algae, are ancient photosynthetic organisms that grow in brackish or fresh water. Species within several genera and some strains within these species produce potent toxins that can induce severe illness in animals and people. Although cyanobacterial toxins (cyanotoxins) are important environmental contaminants, public health activities are limited to emergency responses to specific poisoning events. However, more long-term public health issues, such as cyanotoxins in drinking water, have also been identified. The potential for human exposure to cyanobacterial toxins through their drinking water has been inadequately evaluated, and the public health impact from exposure to these toxins remains unknown. The response to this emerging issue will include assessing exposure, conducting epidemiologic research, and providing public health interventions.

Human intoxication by microcystins during renal dialysis treatment in Caruaru - Brazil
Author: Azevedo, SMFO; Carmichael, WW; Jochimsen, EM; Rinehart, KL; Lau, S; Shaw, GR; Eaglesham, GK
Affiliation: Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro
Source: Toxicology Vol. 181-182, pp. 441-446. 27 Dec 2002.

Abstract: In February 1996, an outbreak of illness occurred at a hemodialysis clinic in Caruaru, Pernambuco State--Brazil. At this clinic 116 (89%) of 131 patients experienced visual disturbances, nausea, vomiting, and muscle weakness, following routine haemodialysis treatment. Subsequently, 100 patients developed acute liver failure. As of December 1996, 52 of the deaths could be attributed to a common syndrome now called 'Caruaru Syndrome'. Examination of previous years' phytoplankton counts showed that cyanobacteria were dominant in the water supply reservoir since 1990. Analyses of carbon and other resins from the clinic's water treatment system plus serum and liver tissue of patients led to the identification of two groups of hepatotoxic cyanotoxins: microcystins (cyclic heptapeptides) in all of these samples and cylindrospermopsin (alkaloid hepatotoxic) in the carbon and resins. Comparison of victims symptoms and pathology with animal studies on these two cyanotoxins, leads us to conclude that the major contributing factor to death of the dialysis patients was intravenous exposure to microcystins, specifically microcystin-YR, -LR and -AR. In 2000, a review of the Brazilian regulation for drinking water quality, promoted by Brazilian Health Ministry with collaboration of PAHO, incorporated cyanobacteria and cyanotoxins into this new regulation as parameters that must to be monitored for water quality control.

Public Outreach Materials Regarding Harmful Algal Blooms and Their Possible Effects on Human Health
Author: Kirkpatrick, B; Fleming, LE; Stephan, WB; Backer, L; Clark, R; Squicciarini, D; Weisman, R; Van De Bogart, G
Affiliation: Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA
Source: Journal of PhycologyVol. 38, no. S1, pp. 18-19. Jun 2002.

Abstract: The potential interactions between marine and freshwater harmful algal blooms (HABs) and humans are increasing. Humans are exposed through food, drinking water, and recreational and occupational water use to an increasing number of organisms and their toxins. Nevertheless, the amount of clinical and epidemiologic research concerning acute and chronic human health effects from the HAB organisms and their toxins is relatively sparse. At the same time, the public is increasingly aware of and interested in the potential dangers associated with exposure to HABs. Public health authorities and researchers must respond to these public health concerns. The development of appropriate educational and outreach materials based on limited scientific databases is the challenge of informing the public concerning the possible human health effects of HAB organisms and their toxins, and their prevention. Educational meterials developed by a group of researchers and public health personnel for general HABs, Florida Red Tide Toxins (brevetoxins), Cyanobacteria, and Ciguatera are discussed, as well as methods for their dissemination.

Toxins and bioactive compounds from cyanobacteria and their implications on human health
Author: Rao, PVL; Gupta, N; Bhaskar, ASB; Jayaraj, R
Affiliation: Division of Pharmacology and Toxicology, Defence Research and Development Establishment
Source: Journal of Environmental Biology Vol. 23, no. 3, pp. 215-224. Jul 2002.

Abstract: Many species of cyanobacteria (blue-green algae) produce secondary metabolites with potent biotoxic or cytotoxic properties. These metabolites differ from the intermediates and cofactor compounds that are essential for cell structural synthesis and energy transduction. The mass growth of cyanobacteria which develop in fresh, brackish and marine waters commonly contain potent toxins. Cyanobacterial toxins or cyanotoxins are responsible for or implicated in animal poisoning, human gastroenteritis, dermal contact irritations and primary liver cancer in humans. These toxins (microcystins, nodularins, saxitoxins, anatoxin-a, anatoxin-a(s), cylindrospermopsin) are structurally diverse and their effects range from liver damage, including liver cancer to neurotoxicity. Several incidents of human illness and more recently, the death of 60 haemodialysis patients in Caruaru, Brazil, have been linked to the presence of microcystins in water. In response to the growing concern about the non-lethal acute and chronic effects of microcystins, World Health Organization has recently set a new provisional guideline value for microcystin-LR of 1.0 mu g/L in drinking water. Cyanobacteria including microcystin-producing strains produce a large number of peptide compounds, e.g. micropeptins, cyanopeptolins, microviridin, circinamide, aeruginosin, with varying bioactivities and potential pharmacological application. This article discusses briefly cyanobacterial toxins and their implications on human health.

Treatment of taste and odor material by oxidation and adsorption
Author: Jung, S-W; Baek, K-H; Yu, M-J
Affiliation: Korea Water Resources Corporation, Korea
Source: Off-Flavours in the Aquatic Environment VI. pp. 289-295. Water Science & Technology Vol. 49, no. 9. 2002

Abstract: Massive blooms of blue-green algae in reservoirs produce the musty-earthy taste and odor, which are caused by compounds such as 2-MIB and geosmin. 2-MIB and geosmin are rarely removed by conventional water treatment. Their presence in the drinking water, even at low levels (ng/L), can be detected and it creates consumer complaints. So those concentrations have to be controlled as low as possible in the drinking water. The removals by oxidation (O sub(3), Cl sub(2), ClO sub(2)) and adsorption (PAC, filter/adsorber) were studied at laboratory and pilot plant (50 m3/d) to select suitable 2-MIB and geosmin treatment processes. The following conclusions were derived from the study. Both of the threshold odor levels for 2-MIB and geosmin appeared to be 30 ng/L as a consequence of a lab test. For any given PAC dosage in a jar-test, removal efficiencies of 2-MIB and geosmin were increased in proportion to PAC dosage and were independent of their initial concentration in raw water for the tested PAC dosages. In comparison of geosmin with 2-MIB, the adsorption efficiency of geosmin by PAC was superior to that of 2-MIB. The required PAC dosages to control below the threshold odor level were 30 mg/L for geosmin and 50 mg/L for 2-MIB at 100 ng/L of initial concentration. Removal efficiencies of odor materials by Cl sub(2), ClO sub(2), and O sub(3) were very weak under the limited dosage (1.5 mg/L), however increased ozone dosage (3.8 mg O sub(3)/L) showed high removal efficiency (84.8% for 2-MIB) at contact time 6.4 minutes. According to the initial concentrations of 2-MIB and geosmin, their removal efficiencies by filter/adsorber differed from 25.7% to 88.4%. For all those, however, remaining concentrations of target materials in finished waters were maintained below 30 ng/L. The longer run-time given for the filter/adsorber, the higher the effluent concentration generated. So it is necessary that the run-time of the filter/adsorber be decreased, when 2-MIB or geosmin occurs in raw water.

2001

Health Effects of Toxin-Producing Cyanobacteria: “The CyanoHABs”
Author: Carmichael, WW
Affiliation: Wright State University, Department of Biological Sciences
Source: Human and Ecological Risk Assessment.]. Vol. 7, no. 5, pp. 1393-1407. Oct 2001

Abstract: Increasingly, harmful algal blooms (HABs) are being reported worldwide due to several factors, primarily eutrophication, climate change and more scientific monitoring. All but cyanobacteria toxin poisonings (CTPs) are mainly a marine occurrence. CTPs occur in fresh (lakes, ponds, rivers and reservoirs) and brackish (seas, estuaries, and lakes) waters throughout the world. Organisms responsible include an estimated 40 genera but the main ones are Anabaena, Aphanizomenon, Cylindrospermopsis, Lyngbya, Microcystis, Nostoc, and Oscillatoria (Planktothrix). Cyanobacteria toxins (cyanotoxins) include cytotoxins and biotoxins with biotoxins being responsible for acute lethal, acute, chronic and sub-chronic poisonings of wild/domestic animals and humans. The biotoxins include the neurotoxins; anatoxin-a, anatoxin-a (s) and saxitoxins plus the hepatotoxins; microcystins, nodularins and cylindrospermopsins. Confirmations of human deaths from cyanotoxins are limited to exposure through renal dialysis at a haemodialysis center in Caruaru, Brazil, in 1996. A major effort to compile all available information on toxic cyanobacteria including issues of human health, safe water practices, management, prevention and remediation have been published by the World Health Organization. This paper will review our current understanding of CTP's including their risk to human health.

Microcystin algal toxins in source and finished drinking water
Author: Karner, DA; Standridge, JH; Harrington, GW; Barnum, RP
Affiliation: Wisconsin State Laboratory of Hygiene, Madison, Wis, USA
Source: Journal of the American Water Works Association Vol. 93, no. 8, pp. 72-81. Aug 2001.

Abstract: Blue-green algae (cyanobacteria) occurrence in surface waters is on the increase worldwide. Certain species of cyanobacteria may produce potent toxins such as microcystins, i.e., hepatotoxins that can cause liver damage, shock, and in some cases, death to those ingesting contaminated water. Conflicting literature about the efficacy of conventional drinking water treatment to remove algal toxins sparked a two-year research project examining surface waters in Wisconsin. A 1998 study evaluated the occurrence of microcystins in raw and finished drinking water at five water treatment plants. A 1999 study monitored microcystin levels at different points in the water treatment train to determine which steps effectively removed the toxins. The studies found that microcystin toxins commonly occurred in untreated surface waters and could, under appropriate conditions, exceed levels deemed safe for human consumption by the World Health Organization. Addition of pretreatment chemicals reduced microcystin concentrations by an average of 61%. Alum coagulation followed by sedimentation or lime softening followed by sedimentation increased toxin reduction to an average of 96%. Further studies are needed to address both other classes of toxins and other treatment processes. Nevertheless, these findings indicate that conventional treatment processes and in particular the use of pretreatment chemicals can help water suppliers successfully deal w ith the emerging threat of algal toxins.

Using coagulation, flocculation, and settling to remove toxic cyanobacteria
Author: Drikas, M
Affiliation: Australian Water Quality Centre, Hodgson Road, Private Mail Bag 3, Bolivar, South Australia 5108
Source: Journal of the American Water Works Association Vol. 93, no. 2, pp. 100-111. Feb 2001.

Abstract: Cyanobacteria (blue-green algae) produce toxins and tastes and odors that can significantly impair water quality. The removal of cyanobacterial cells without cell damage could significantly reduce the concentration of tastes, odors, and toxic cell metabolites present in treated water. Cultured cyanobacterium, hepatotoxic Microcystis aeruginosa, was mixed with reservoir water to simulate water entering a treatment plant during an algal bloom. A bench-top jar-test apparatus (flocculation) and a full-scale pilot plant (flocculation-sedimentation-filtration) rated at 600 mL/min were used to evaluate the effectiveness of conventional water treatment processes in removing cyanobacterial cells. Removal of cells by flocculation using a jar-test apparatus with aluminum sulfate dosed at concentrations used in water treatment practice varied between 70 and 83%. Results obtained from the pilot experiment indicated 99.9% of the cells were removed. More important, no additional release of microcystin (toxin) was found in the finished water.

Zebra mussel (Dreissena polymorpha) selective filtration promoted toxic Microcystis blooms in Saginaw Bay (Lake Huron) and Lake Erie
Author: Vanderploeg, HA; Liebig, JR; Carmichael, WW; Agy, MA; Johengen, TH; Fahnenstiel, GL; Nalepa, TF
Source: Canadian Journal of Fisheries and Aquatic Sciences Vol. 58, no. 6, pp. 1208-1221. Jun 2001.

Abstract: Microcystis aeruginosa, a planktonic colonial cyanobacterium, was not abundant in the 2-year period before zebra mussel (Dreissena polymorpha) establishment in Saginaw Bay ( Lake Huron) but became abundant in three of five summers subsequent of mussel establishment. Using novel methods, we determined clearance, capture, and assimilation rates for zebra mussels feeding on natural and laboratory M. aeruginosa strains offered alone or in combination with other algae. Results were consistent with the hypothesis that zebra mussels promoted blooms of toxic M. aeruginosa in Saginaw Bay, western Lake Erie, and other lakes through selective rejection in pseudofeces. Mussels exhibited high feeding rates similar to those seen for a highly desirable food alga (Cryptomonas) with both large (›53 mu m) and small (‹53 mu m) colonies of a nontoxic and a toxic laboratory strain of M. aeruginosa known to cause blockage of feeding in zooplankton. In experiments with naturally occurring toxic M. aeruginosa from Saginaw Bay and Lake Erie and a toxic isolate from Lake Erie, mussels exhibited lowered or normal filtering rates with rejection of M. aeruginosa in pseudofeces. Selective rejection depended on “unpalatable” toxic strains of M. aeruginosa occurring as large colonies that could be rejected efficiently while small desirable algae were ingested.