Cyanobacterial Harmful Algal Blooms: State of the Science and Research Needs
Hudnell, H. Kenneth (Ed.)
Interagency ISOC-HAB Symposium Introduction This symposium was held to assess the state-of-the-science and identify research needed to address the increasing risks posed by freshwater harmful algal blooms to human health and ecosystem sustainability. Information obtained through the symposium will help form the scientific basis for developing and implementing strategies to reduce these risks. All chapters in this book are based on platform sessions or draft workgroup reports that were presented at ISOC-HAB. All chapters were completed after the conclusion of ISOC-HAB. Each chapter was critically reviewed by at least two peers with expertise in the subject matter, revised based on those reviews, and reviewed by the editor before being accepted for publication.
Health effects associated with controlled exposures to cyanobacterial toxins
Ian R Falconer
The cyanobacterial toxins of concern as potential human health hazards are those known to occur widely in drinking water sources, and therefore may be present in water for human use. The toxins include a diverse range of chemical compounds, with equally diverse toxic effects. These toxins are not limited to individual cyanobacterial species or genera, and all of the toxins of concern to human health are produced by multiple cyanobacterial species.
Emerging high throughput analyses of cyanobacterial toxins and toxic cyanobacteria
Toxic cyanobacterial mass occurrences (blooms) are commonly found in fresh, brackish, and marine waters (Sivonen and Jones 1999). Cyanobacteria growing in benthic environments have also been shown to contain toxins (Sivonen and Jones 1999; Edwards et al. 1992; Mez et al. 1997; Surakka et al. 2005). The most common cyanobacterial toxins (cyanotoxins) are hepatotoxins (microcystins and nodularins), neurotoxins [anatoxin–a, anatoxin–a(S) and saxitoxins], cytotoxins (cylindrospermopsins), and dermatotoxins (aplysiatoxin and debromoaplysiatoxins) (Sivonen and Jones 1999). Microcystins in freshwaters are most frequently produced by Microcystis, Planktothrix (formerly Oscillatoria) and Anabaena (Sivonen and Jones 1999)....
Over recent years it has become apparent that toxic cyanobacterial blooms are on the increase, presenting a hazard to animal and human health (Appendix A, Table A.1). The importance of algal toxins is reflected in their inclusion of EPA recognised contaminants in water (Richardson and Ternes 2005). Microcystins have been extensively studied and reported over recent years. Despite the number of microcystin variants and lack of standards, a large number of biological and chemical methods have been optimised for a variety of matrices, usually cells, water and tissue. Data on chronic and acute toxicity have led to the WHO to set a guideline maximum of 1 µg per litre in drinking water. Methods developed for microcystins are suitable for the pentapeptide nodularins, although these cyanotoxins usually occur in brackish water. ...
Field methods in the study of toxic cyanobacterial blooms: results and insights from Lake Erie Research
Steven W Wilhelm
Sound field methodologies are an essential prerequisite in the development of a basic understanding of toxic cyanobacteria blooms. Sample collection, on–site processing, storage and transportation, and subsequent analysis and documentation are all critically dependent on a sound field program that allows the researcher to construct, with minimal uncertainty, linkages between bloom events and cyanotoxin production with the ecology of the studied system. Since 1999, we have collected samples in Lake Erie as part of the MELEE (Microbial Ecology of the Lake Erie Ecosystem) and MERHAB–LGL (Monitoring Event Responses for Harmful Algal Blooms in the Lower Great Lakes) research programs to develop appropriate tools and refine methods necessary to characterize the ecology of the reoccurring cyanobacterial blooms in the systems. Satellite imagery, large ship expeditions, classical and novel molecular tools have been combined to provide insight into both the cyanobacteria responsible for these events as well as into some of the environmental cues that may facilitate the formation of toxic blooms. This information, as well new directions in cyano– specific monitoring will be presented to highlight needs for field program monitoring and/or researching toxic freshwater cyanobacteria.
Determining important parameters related to cyanobacterial alkaloid toxin exposure
Adam H Love
The United States is faced with having to address critical issues that have not been addressed in the past, as recent security interests have placed new and more pressing demands on the assessment of risk from exposure to potential threats resulting from deliberate contamination. Such assessments are the basis for decisions about future research priorities, actions taken to prevent intentional contaminant releases, and developing detailed plans for response if such an event was to occur. High fidelity assessments are based on robust knowledge of the numerous parameters that can be used to predict the fate, transport, persistence, and toxicity for contaminants under numerous circumstances. Therefore, identification and determination of these parameters are the primary steps for evaluation of potential threats....
Harmful cyanobacterial blooms represent one of the most serious ecological stressors in lakes, rivers, estuaries and marine environments. When there are persistent or frequent blooms with high biomass of cyanobacterial cells, colonies or filaments in the water, a wide range of impacts on the ecosystem may occur. These are well established in the scientific literature and are summarized in Paerl et al. (2001). Blooms may shade the water and thereby inhibit growth of other primary producers including phytoplankton, benthic algae and vascular plants and may elevate pH, particularly in poorly buffered waters. High population densities of large cyanobacteria interfere with food collection by filter–feeding zooplankton. The senescence and subsequent microbial decomposition of blooms may impact benthic macro–invertebrate community structure, as well as fish and other biota, due to increased organic loading and resulting anoxia of sediments, accumulation of NH4 in the water and accompanying increases in pH. Blooms of toxic cyanobacteria have been implicated in mass mortalities of birds and fish (e.g., Matsunaga et al. 1999; Rodger et al. 1994) ...
The genetics and genomics of cyanobacterial toxicity
Brett A Neilan, Pearson LA, Moffitt MC, Mihali KT, Kaebernick M, Kellmann R, Pomati F
The past ten years has witnessed major advances in our understanding of natural product biosynthesis, including the genetic basis for toxin production by a number of groups of cyanobacteria. Cyanobacteria produce an unparalleled array of bioactive secondary metabolites; including alkaloids, polyketides and non–ribosomal peptides, some of which are potent toxins. This paper addresses the molecular genetics underlying cyanotoxin production in fresh and brackish water environments. The major toxins that have been investigated include microcystin, cylindrospermopsin, nodularin, the paralytic shellfish poisons (PSP), including saxitoxin, and the anatoxins. ...
Cyanobacterial toxins: a qualitative meta–analysis of concentrations, dosage and effects in freshwater, estuarine and marine biota
Bas W Ibelings1 , Karl E Havens2
This paper reviews the rapidly expanding literature on the ecological effects of cyanobacterial toxins. The study employs a qualitative meta– analysis from the literature examining results from a large number of independent studies and extracts general patterns from the literature or signals contradictions. The meta–analysis is set up by putting together two large tables – embodying a large and representative part of the literature (see Appendix A). The first table (Table A.1) reviews the presence (concentrations) of different cyanobacterial toxins in the tissues of various groups of aquatic biota after exposure via different routes, experimentally in the lab or via natural routes in the environment. The second table (Table A.2) reviews the dose dependent effect of toxins on biota. The great majority of studies deal with the presence and effects of microcystin, especially of the MC–LR congener. Although this may partly be justified – MC–LR is an abundant and highly toxic protein – our review also emphasizes what is known about (i) other MC congeners (a number of studies showed a preferred accumulation of the less toxic variant MC–RR in animal tissues), (ii) nodularin (data on a range of biota from studies on the Baltic Sea), (iii) neurotoxins like anatoxin–a(s), which are conspicuously often present at times when mass mortalities of birds occur, (iv) a few studies on the presence and effects of cylindrospermposin, as well as (v) the first examples of ...
Cyanobacteria blooms: effects on aquatic ecosystems
Karl E Havens
Lakes, rivers and estuaries that experience frequent and/or prolonged blooms of cyanobacteria display an array of ecosystem properties that may have impacts on water quality, biological communities and ecosystem services. Some impacts of blooms may be direct, including possible effects of toxins on fish, invertebrates, and other aquatic fauna, or indirect, including: a reduction of submerged plants when plankton biomass becomes very high; and changes in fish community structure if summer cold water refuges are lost due to hypolimnetic anoxia. This paper is a concise overview of cyanobacteria blooms, focusing on their relationship to trophic state, their temporal dynamics, and their potential impacts on ecosystem structure and function.
Co–chairs: Joyce Donohue and Jennifer Orme–Zavaleta
Risk assessment is a four–stage process used in evaluating the impact of contaminants on the well being of individuals, populations and/or the physical environment. As defined by the National Academy of Sciences (1983), the four components are as follows: hazard identification, dose– response assessment, exposure assessment and risk characterization. The goal of a risk assessment is to utilize existing information coupled with site specific data to quantitatively characterize the potential risk of a stressor to an identified receptor(s). Quantitative, risk–based estimates of dose–response relationships integrated with exposure scenarios and information on environmental conditions often become the basis for regulatory measures or management policies to protect the population or physical environment from harm. The precision of the guideline value is impacted by the quantity and quality of scientific data available because uncertainty factors are applied in its derivation to compensate for deficiencies in the database. The more comprehensive the database, the lower the uncertainty in the risk assessment and the more precise the value generated....
Cyanobacterial blooms impact upon the water quality, environmental and ecological status of water bodies and affect most of the uses we make of water. The extent of the impact depends upon the type, size and frequency of the blooms, the size of the water body affected, the uses made of the water and the treatment options available to respond to the blooms. The impacts therefore vary considerably from place to place. Overall costs should also account for the planning and remedial actions taken to prevent future blooms.
Toxin mixture in cyanobacterial blooms – a critical comparison of reality with current procedures employed in human health risk assessment
Daniel R Dietrich, Fischer A, Michel C, Hoeger SJ
Cyanobacteria are the oldest life forms on earth known to produce a broad spectrum of secondary metabolites. The functions/advantages of most of these secondary metabolites (peptides and alkaloids) are unknown, however, some of them have adverse effects in humans and wildlife, especially when ingested, inhaled or upon dermal exposure. Surprisingly, some of these cyanobacteria are ingested voluntarily. Indeed, for centuries mankind has used cyanobacteria as a protein source, primarily Spirulina species. However, recently also Aphanizomenon flos–aquae are used for the production of so called blue green algae supplements (BGAS), supposedly efficacious for treatment of various diseases and afflictions. Unfortunately, traces of neurotoxins and protein phosphatases (inhibiting compounds) have been detected in BGAS, making these health supplements a good example for human exposure to a mixture of cyanobacterial toxins in a complex matrix. The discussion of this and other possible exposure scenarios, e.g. drinking water, contact during recreational activity, or consumption of contaminated food, can provide insight into the question of whether or not our current risk assessment schemes for cyanobacterial blooms and the toxins contained therein suffice for protection of human health.
Integrating human and ecological risk assessment: application to the cyanobacterial harmful algal bloom problem
Jennifer Orme-Zavaleta, Wayne R Munns Jr
Environmental and public health policy continues to evolve in response to new and complex social, economic and environmental drivers. Globalization and centralization of commerce, evolving patterns of land use (e.g., urbanization, deforestation), and technological advances in such areas as manufacturing and development of genetically modified foods have created new and complex classes of stressors and risks (e.g., climate change, emergent and opportunist disease, sprawl, genomic change). In recognition of these changes, environmental risk assessment and its use are changing from stressor-endpoint specific assessments used in command and control types of decisions to an integrated approach for application in communitybased decisions. As a result, the process of risk assessment and supporting risk analyses are evolving to characterize the human-environment relationship. Integrating risk paradigms combine the process of risk estimation for humans, biota, and natural resources into one assessment to improve the information used in environmental decisions (Suter et al. 2003b). A benefit to this approach includes a broader, system-wide evaluation that considers the interacting effects of stressors on humans and the environment, as well the interactions between these entities. To improve our understanding of the linkages within complex systems, risk assessors will need to rely on a suite of techniques for conducting rigorous analyses characterizing the exposure and effects relationships between stressors and biological receptors. Many of the analytical techniques routinely employed are narrowly focused and unable to address the complexities of an integrated assessment. In this paper, we describe an approach to integrated risk assessment, and discuss qualitative community modeling and Probabilistic Relational Modeling techniques that address these limitations and evaluate their potential for use in an integrated risk assessment of cyanobacteria.
Cyanotoxins: sampling, sample processing and toxin uptake
Jussi AO Meriluoto, Lisa EM Spoof
There are several cyanobacterial (blue–green algal) toxin groups which have been implicated in human and animal illnesses and mortalities. Sampling and sample processing of cyanotoxins will be discussed as well as toxin uptake in different organisms.
Cyanobacterial poisoning in livestock, wild mammals and birds – an overview
Ian Stewart1,2, Alan A. Seawright1 , Glen R. Shaw2,3
Poisoning of livestock by toxic cyanobacteria was first reported in the 19th century, and throughout the 20th century cyanobacteria–related poisonings of livestock and wildlife in all continents have been described. Some mass mortality events involving unrelated fauna in prehistoric times have also been attributed to cyanotoxin poisoning; if correct, this serves as a reminder that toxic cyanobacteria blooms predate anthropogenic manipulation of the environment, though there is probably general agreement that human intervention has led to increases in the frequency and extent of cyanobacteria blooms. Many of the early reports of cyanobacteria poisoning were anecdotal and circumstantial, albeit with good descriptions of the appearance and behaviour of cyanobacteria blooms that preceded or coincided with illness and death in exposed animals. Early necropsy findings of hepatotoxicity were subsequently confirmed by experimental investigations. More recent reports supplement clinical and post–mortem findings with investigative chemistry techniques to identify cyanotoxins in stomach contents and tissue fluids.
The Cyanotoxins Workgroup was charged with the identification and prioritization of research needs associated with: the identification of cyanotoxins; toxicokinetics and toxicodynamics of cyanotoxins; human susceptibility to the toxins; cyanobacterial genetics/omics and factors for inclusion in predictive models of toxin production; and risk reduction from an intentional or accidental release of cyanotoxins. Papers presented for the Cyanotoxins Session of the symposium on toxin types, toxicokinetics, and toxicodyamics (See Humpage this volume), cyanobacterial genetics of toxin production (See Neilan this volume), and parameters related to human risks from cyanobacterial exposure (See Love this volume) set the stage for Cyanotoxins Workgroup discussions.
Cyanobacteria produce a wide array of bioactive secondary metabolites (see Table A.1 in Appendix A), some which are toxic (Namikoshi and Rinehart 1996; Skulberg 2000). Those toxic to mammals include the microcystins, cylindrospermopsins, saxitoxins, nodularins, anatoxin-a, homoanatoxin-a, and anatoxin-a(s). It has been recently suggested that β- methylamino alanine (BMAA) may be a new cyanobacterial toxin (Cox et al. 2003; Cox et al. 2005). The public health risks of cyanotoxins in drinking water have recently been reviewed (Falconer and Humpage 2005b). The aim of this paper is to concisely review our current knowledge of their acute toxicity, mechanisms of action, toxicokinetics and toxicodynamics.
Epidemiology is defined as the study of the distribution and determinants of health–related states or events in specified populations, and the application of this study to the control of health problems (Last 2001). In this context, "study" includes observation, hypothesis testing, analytic research, and experiments. In turn, each of these methods has an increasing level of sophistication that provides results with differing strength of evidence linking human exposure and health outcome. The World Health Organisation and other agencies, including the National Health and Medical Research Council (NHMRC) in Australia, have developed a classification system for these levels of evidence based on rigor, quality and the minimisation of bias. The NHMRC’s new pilot classification allows for studies about aetiology. ...
A world overview — One-hundredtwenty-seven years of research on toxic cyanobacteria — Where do we go from here?
Both marine and freshwater Harmful Algal Blooms (HABs) have been observed throughout history. The first literature reference for toxic cyanobacteria (CyanoHABs) was in 1878. George Francis issued a report on sheep and cattle deaths from the brackish water cyanobacteria Nodularia spumigena in Nature called ”Poisonous Australian Lake”. For the marine HABs, a 1928 report in the Journal of Preventive Medicine described human intoxication from mussel poisoning cases in the San Francisco area during July of 1927. This led to work that described the first phycotoxin group, Saxitoxins, by Edward Schantz in the 1950’s. In response the occurrence of red tides in New England during 1972, the First International Conference on Toxic Dinoflagellate Blooms was held in 1974. Currently there are twelve international marine HAB conferences. The First International Conference on Toxic Cyanobacteria proceedings, “The Water Environment Algal Toxins and Health”, was published in 1981. The 7th such conference is scheduled to be held in Brazil in 2007. United States (U.S.) HAB response resulted in the development of a U.S. National Plan for Marine Biotoxins and Harmful Algae (Anderson et al. 1993), which led to “The Harmful Algal Bloom and Hypoxia Research and Control Act of 1998 written by the U.S. Senate-Subcommittee on Oceans and Fisheries. In the 2003 revision of this act the U.S. house of representatives included fresh-water algae especially the harmful cyanobacteria. The current national plan is called Harmful Algal Research and Response; a National Environmental Science Strategy 2005-2015 (HARRNESS) (Ramsdell et al. (eds) 2005). This CyanoHAB Overview will focus on occurrences of cyanobacteria and cyanotoxins that have been observed in freshwater, drinking water, recreational water, estuaries and marine water, as well as the impacts on health and/or ecosystem viability in the U.S. and worldwide.
An Overview of the Interagency, International Symposium on Cyanobacterial Harmful Algal Blooms (ISOC-HAB): Advancing the Scientific Understanding of Freshwater Harmful Algal Blooms
H Kenneth Hudnell, Quay Dortch, Harold Zenick
There is growing evidence that the spatial and temporal incidence of harmful algal blooms is increasing, posing potential risks to human health and ecosystem sustainability. Currently there are no US Federal guidelines, Water Quality Criteria and Standards, or regulations concerning the management of harmful algal blooms. Algal blooms in freshwater are predominantly cyanobacteria, some of which produce highly potent cyanotoxins. The US Congress mandated a Scientific Assessment of Freshwater Harmful Algal Blooms in the 2004 reauthorization of the Harmful Algal Blooms and Hypoxia Research and Control Act. To further the scientific understanding of freshwater harmful algal blooms, the US Environmental Protection Agency (EPA) established an interagency committee to organize the Interagency, International Symposium on Cyanobacterial Harmful Algal Blooms (ISOC-HAB). A theoretical framework to define scientific issues and a systems approach to implement the assessment and management of cyanobacterial harmful algal blooms were developed as organizing themes for the symposium. Seven major topic areas and 23 subtopics were addressed in Workgroups and platform sessions during the symposium. The primary charge given to platform presenters was to describe the state of the science in the subtopic areas, whereas the Workgroups were charged with identifying research that could be accomplished in the short- and long-term to reduce scientific uncertainties. The proceedings of the symposium, published in this monograph, are intended to inform policy determinations and the mandated Scienific Assessment by describing the scientific knowledge and areas of uncertainty concerning freshwater harmful algal blooms.
Cyanobacteria are an important ecological component of all freshwater, estuarine and marine ecosystems worldwide. They contribute significantly to ecosystem productivity – sometimes excessively. When this occurs they also form water ‘blooms’ which are now recognised as a serious water quality problem with our use of water both for drinking water supply, recreational amenity and for agricultural use. Blooms are a symptom of eutrophication and are evidence of the deterioration of our water resources as a result of effluent discharge, poor land and catchment management, and often also of poor water allocation practices in rivers. This is now becoming better understood and acknowledged both in the United States and worldwide (Burns 2005, Chorus and Bartram, 1999).
The conditions which favour the growth of cyanobacteria and lead to blooms are nutrient enrichment (largely phosphorus but also nitrogen), warm temperatures, and calm stable water conditions such as those occurring in thermally stratified lakes and slow-flowing rivers. The latter may be the result of hydrology altered by abstraction practices. These conditions are often caused by human actions and activities, but can also be associated with natural climatic cycles such as droughts.
There is an international consensus that there has been an increase in frequency and severity of harmful algal blooms in both the marine and freshwater environments. In the case of the fresh water environment, the occurrence of toxic cyanobacterial blooms (CyanoHABs) presents problems for treatment, management and regulation of the quality of drinking water supplies. In regard to cyanotoxins a number of countries however have developed regulations or guidelines for cyanotoxins and cyanobacteria in drinking water, and in some cases in water used for recreation and agriculture. There are currently no federal regulations or guidelines in the US for protecting human health and ecosystem viability from cyanobacterial harmful algal blooms (CyanoHABs) that occur in fresh, estuary, and marine water environments. This paper will explore the regulations and guidelines that have been developed around the world, identify others that may be needed, identify research needed to support their development, and identify factors that would be needed in a model to predict the need for revised and/or additional regulations or guidelines concerning CHABs.
A Synopsis of Research Needs Identified at the Interagency, International Symposium on Cyanobacterial Harmful Algal Blooms (ISOC-HAB)
H Kenneth Hudnell and Quay Dortch
Evidence indicates that the incidence of cyanobacterial harmful algal blooms (CHABs) is increasing in spatial extent and temporal frequency worldwide. Cyanobacterial blooms produce highly potent toxins and huge, noxious biomasses in surface waters used for recreation, commerce, and as drinking water sources. The Interagency, International Symposium on Cyanobacterial Harmful Algal Blooms (ISOC-HAB) characterized the state of the science and identified research needed to address the risks posed by CHABs to human health and ecosystem sustainability. This chapter provides a synopsis of CHAB research needs that were identified by workgroups that addressed charges in major topic areas. The research and infrastructure needed are listed under nine categories: 1) Analytical Methods; 2) CHAB Occurrence; 3) CHAB Causes; 4) Human Health; 5) Ecosystem Sustainability; 6) CHAB Prevention; 7) CHAB Control and Mitigation; 8) Risk Assessment and; 9) Infrastructure. A number of important issues must be addressed to successfully confront the health, ecologic, and economic challenges presented by CHABs. Near-term research goals include the development of field-ready tests to identify and quantify cells and toxins, the production of certified reference standards and bulk toxins, formal assessments of CHAB incidence, improved understanding of toxin effects, therapeutic interventions, ecologically benign means to prevent and control CHABs, supplemental drinking water treatment techniques, and the development of risk assessment and management strategies. Longterm goals include the assimilation of CHAB databases into emerging U.S. and international observing systems, the development of quantitative models to predict CHAB occurrence, effects, and management outcomes, and economic analyses of CAHB costs and management benefits. Accomplishing further infrastructure development and freshwater HAB research is discussed in relationship to the Harmful Algal Blooms and Hypoxia Research and Control Act and existing HAB research programs. A sound scientific basis, the integration of CHAB infrastructure with that of the marine HAB community, and a systems approach to risk assessment and management will minimize the impact of this growing challenge to society.
The topic of exposure assessment overlaps with other topic areas of this workshop. It includes considerations of establishment of long term monitoring and event response, sampling protocols, development and standardization of organism and toxin assays, funding mechanisms, and public outreach. The development of a coordinated infrastructure (funding, human resources, and facilities, materials and equipment) is key to successfully addressing the threat posed by CHABs. The establishment of validated standardized protocols to detect cyanobacteria and cyanotoxins is of considerable importance given the increased occurrence of CHABs worldwide. Standardized methods are needed for studies assessing occurrence, monitoring and toxicity studies which are essential aspects of risk assessment and management and the development of guidance and regulation.
Nebraska agencies and public health organizations collaboratively addressed cyanobacterial issues for the first time after two dogs died within hours of drinking water from a small private lake south of Omaha on May 4, 2004. A necropsy on one of the dogs revealed that the cause of death was due to ingestion of Microcystin toxins. Within two weeks after the dog deaths, state and local officials jointly developed strategies for monitoring cyanobacterial blooms and issuing public health alerts and advisories. Weekly sampling of public lakes for microcystin toxins and cyanobacteria was initiated during the week of May 17, 2004. ELISA laboratory equipment and supplies were purchased to achieve a quick turnaround time for measuring weekly lake samples for total microcystins so that public health advisories and alerts could be issued prior to each weekend’s recreational activities. A conservative approach was selected to protect human health, pets, and livestock, which included collecting worst-case samples from cyanobacterial blooms; freezing and thawing of samples to lyse algal cells and release toxins prior to laboratory analysis; and using action levels of 15 ppb and 2 ppb of total microcystins, respectively, for issuing health alerts and health advisories. During 2004, five dog deaths, numerous wildlife and livestock deaths, and more than 50 accounts of human skin rashes, lesions, or gastrointestinal illnesses were reported at Nebraska lakes. Health alerts were issued for 26 lakes and health advisories for 69 lakes. Four lakes were on health alert for 12 or more weeks. The primary cyanobacterial bloomforming genera identified in Nebraska lakes were Anabaena, Aphanizomenon, and Microcystis. Preliminary assessments of lake water quality data indicated that lower lake levels from the recent drought and low nitrogen to phosphorus ratios may have contributed, in part, to the increased numbers of cyanobacterial complaints and problems that occurred in 2004.
Cyanobacterial Toxins in New York and the Lower Great Lakes Ecosystems
Gregory L Boyer
Toxic cyanobacterial blooms are an increasing problem in the lower Laurentian Great Lakes. To better understand their occurrence and distribution, samples for particulate toxin analysis were collected from more than 140 New York Lakes including Lakes Erie, Champlain and Ontario. Microcystins were of most importance and were detected in nearly 50% of the samples. Anatoxin-a, cylindrospermopsin and the paralytic shellfish toxins occurred much less frequently (0-4%). The implications for the management of cyanobacterial harmful algal blooms are discussed.
Multiple Scenarios for Fisheries to Increase Potentially Toxin Producing Cyanobacteria Populations in Selected Oregon Lakes
Eilers JM,1 St. Amand A2
The dominance of cyanobacteria, many of which produce toxins, in lakes is often associated with external loads of phosphorus from activities in the watersheds. However, we have identified multiple pathways in selected Oregon lakes whereby fisheries management activities play a crucial role in promoting cyanobacteria populations.
Cyanobacterial toxin removal in drinking water treatment processes and recreational waters
Judy A Westrick
Although federal drinking water regulations determine the quality of potable water, many specifics influence how each utility chooses to treatment water. Some of the specifics include source water quality, storage capacity, existing unit process, and space. An overview of the US recreational and drinking water regulations were discussed in context of cyanobacterial toxin removal and inactivation by ancillary as well as auxiliary treatment practices. Ancillary practice refers to the removal or inactivation of algal toxins by standard daily operational procedures where auxiliary treatment practice refers to intentional treatment. An example of auxiliary treatment would be the addition of powder activated carbon to remove taste and odor compounds. The implementation of new technologies as such ultraviolet disinfection and membrane filtration, to meet current and purposed regulations, can greatly affect the algal toxin removal and inactivation efficiencies. A discussion on meeting the current regulations by altering chemical disinfection, ozone, chlorine, chloramines and chlorine dioxide included their ancillary effects on the protection against algal toxins. Although much of the research has been on the efficiency of the removal and inactivation of microcystin LR and several microcystin variants, the discussion included other algal toxins: anatoxin–a, saxitoxins, and cyclindrospermopsin.
Watershed management strategies to prevent and control cyanobacterial harmful algal blooms
Michael F Piehler
The tenets of watershed management – a focus on the land area linked to the water body, the incorporation of sound scientific information into the decision-making process and stakeholder involvement throughout the process – are well-suited for the management of cyanobacterial harmful algal blooms (C-HABs). The management of C-HABs can be viewed as having two main areas of focus. First, there is mitigation – control and/or removal of the bloom. This type of crisis response is an important component to managing active C-HABs and there are several techniques that have been successfully utilized, including the application of algicides, physical removal of surface scums and the mechanical mixing of the water column. While these methods are valuable because they address the immediate problem, they do not address the conditions that exist in the system that promote and maintain C-HABs. Thus, the second component of a successful C-HAB management strategy would include a focus on prevention. C-HABs require nutrients to fuel their growth and are often favored in longer-residence time systems with vertical stratification of the water column. Consequently, nutrients and hydrology are the two factors most commonly identified as the targets for prevention of C-HABs. Management strategies to control the sources, transformation and delivery of the primary growth-limiting nutrients have been applied with success in many areas. The most effective of these include controlling land use, maintaining the integrity of the landscape and applying best management practices.
In the past, notable successes in managing C-HABs have relied on the reduction of nutrients from point-sources. Because many point sources are now well-managed, current efforts are focused on non-point source nutrient reduction, such as runoff from agricultural and urban areas. Non-point sources present significant challenges due to their diffuse nature. Regardless of which techniques are utilized, effective watershed management programs for decreasing the prevalence of C-HABs will require continuing efforts to integrate science and management activities. Ultimately, it is increased coordination among stakeholders and scientists that will lead to the development of the decision-making tools that managers require to effectively weigh the costs and benefits of these programs.
Global warming and cyanobacterial harmful algal blooms
Valerie J Paul
The Earth and the oceans have warmed significantly over the past four decades, providing evidence that the Earth is undergoing long-term climate change. Increasing temperatures and changing rainfall patterns have been documented. Cyanobacteria have a long evolutionary history, with their first occurrence dating back at least 2.7 billion years ago. Cyanobacteria often dominated the oceans after past mass extinction events. They evolved under anoxic conditions and are well adapted to environmental stress including exposure to UV, high solar radiation and temperatures, scarce and abundant nutrients. These environmental conditions favor the dominance of cyanobacteria in many aquatic habitats, from freshwater to marine ecosystems. A few studies have examined the ecological consequences of global warming on cyanobacteria and other phytoplankton over the past decades in freshwater, estuarine, and marine environments, with varying results. The responses of cyanobacteria to changing environmental patterns associated with global climate change are important subjects for future research. Results of this research will have ecological and biogeochemical significance as well as management implications.
Nutrient and other environmental controls of harmful cyanobacterial blooms along the freshwater–marine continuum
Nutrient and hydrologic conditions strongly influence harmful planktonic and benthic cyanobacterial bloom (CHAB) dynamics in aquatic ecosystems ranging from streams and lakes to coastal ecosystems. Urbanization, agricultural and industrial development have led to increased nitrogen (N) and phosphorus (P) discharge, which affect CHAB potentials of receiving waters. The amounts, proportions and chemical composition of N and P sources can influence the composition, magnitude and duration of blooms. This, in turn, has ramifications for food web dynamics (toxic or inedible CHABs), nutrient and oxygen cycling and nutrient budgets. Some CHABs are capable of N2 fixation, a process that can influence N availability and budgets. Certain invasive N2 fixing taxa (e.g., Cylindrospermopsis, Lyngbya) also effectively compete for fixed N during spring, N–enriched runoff periods, while they use N2 fixation to supplant their N needs during N– deplete summer months. Control of these taxa is strongly dependent on P supply. However, additional factors, such as molar N:P supply ratios, organic matter availability, light attenuation, freshwater discharge, flushing rates (residence time) and water column stability play interactive roles in determining CHAB composition (i.e. N2 fixing vs. non–N2 fixing taxa) and biomass. Bloom potentials of nutrient–impacted waters are sensitive to water residence (or flushing) time, temperatures (preference for >15 o C), vertical mixing and turbidity. These physical forcing features can control absolute growth rates of bloom taxa. Human activities may affect “bottom up” physical–chemical modulators either directly, by controlling hydrologic, nutrient, sediment and toxic discharges, or indirectly, by influencing climate. Control and management of cyanobacterial and other phytoplankton blooms invariably includes nutrient input constraints, most often focused on N and/or P. While single nutrient input constraints may be effective in some water bodies, dual N and P input reductions are usually required for effective long–term control and management of blooms. In some systems where hydrologic manipulations (i.e., plentiful water supplies) are possible, reducing the water residence time by flushing and artificial mixing (along with nutrient input constraints) can be effective alternatives. Blooms that are not readily consumed and transferred up the food web will form a relatively large proportion of sedimented organic matter. This, in turn, will exacerbate sediment oxygen demand, and enhance the potential for oxygen depletion and release of nutrients back to the water column. This scenario is particularly problematic in long–residence time (i.e., months) systems, where blooms may exert a strong positive feedback on future events. Implications of these scenarios and the confounding issues of climatic (hydrologic) variability, including droughts, tropical storms, hurricanes and floods, will be discussed in the context of developing effective CHAB control strategies along the freshwater–marine continuum
СИСТЕМЫ РЕГУЛЯЦИИ СТРЕССОВЫХ ОТВЕТОВ У ЦИАНОБАКТЕРИЙ
А. А. Зорина*, К. С. Миронов*, Н. С. Степанченко*, М. А. Синетова*,
Н. В. Коробан**, В. В. Зинченко**, Е. В. Куприянова*, С. И. Аллахвердиев*,***,
Д. А. Лось*
Журнал "Физиология растений" Т.58,№ 5,г.2011,С.643-663 СИСТЕМЫ РЕГУЛЯЦИИ СТРЕССОВЫХ ОТВЕТОВ У ЦИАНОБАКТЕРИЙ
В обзоре рассмотрены основные системы регуляции генной экспрессии у цианобактерий в ответ на стрессовые воздействия: низкие и высокие температуры, солевой, гиперосмотический, окислительный стресс. Описаны системы восприятия клетками света. Представлена функциональная характеристика известных двухкомпонентных систем регуляции, серин-треониновых протеинкиназ эукариотического типа, -субъединиц РНК-полимеразы, ДНК-связывающих транскрипционных факторов. Проанализированы разные механизмы восприятия стрессовых сигналов, включая изменения степени сверхспирализации ДНК при различных стрессовых воздействиях.
Исследование количественных характеристик цианобактерий перифитона литорали Кольского залива Баренцева моря
Луценко Е.С., Москвина М.И.
Изучение численности и биомассы цианобактерий перифитона станций южного и среднего колен Кольского залива Баренцева моря проведено на трех горизонтах литорали в периоды с декабря 2011 по апрель 2012 и октябрь - ноябрь 2012 гг. Максимумы и минимумы численности и биомассы цианобактерий выявлены на станциях соответственно наиболее и наименее подверженных антропогенному воздействию.