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U.S. Environmental Protection Agency Papers United States Environmental Protection Agency

1-1-2008

Cyanobacterial Harmful Algal Blooms: Chapter 3:

Occurrence of Cyanobacterial Harmful Algal

Blooms Workgroup Report

Anthony Fristachi

James Sinclair

Sherwood Hall

Julie Hambrook Berkman

Greg Boyer

See next page for additional authors

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Fristachi, Anthony; Sinclair, James; Hall, Sherwood; Hambrook Berkman, Julie; Boyer, Greg; Burkholder, JoAnn; Burns, John;

Carmichael, Wayne; DuFour, Al; Frazier, William; Morton, Steve; O’Brien, Eric; and Walker, Steven, "Cyanobacterial Harmful Algal

Blooms: Chapter 3: Occurrence of Cyanobacterial Harmful Algal Blooms Workgroup Report" (2008). U.S. Environmental Protection

Agency Papers. Paper 40.

http://digitalcommons.unl.edu/usepapapers/40
Authors

Anthony Fristachi, James Sinclair, Sherwood Hall, Julie Hambrook Berkman, Greg Boyer, JoAnn Burkholder,

John Burns, Wayne Carmichael, Al DuFour, William Frazier, Steve Morton, Eric O’Brien, and Steven Walker

This article is available at DigitalCommons@University of Nebraska - Lincoln: http://digitalcommons.unl.edu/usepapapers/40
Chapter 3: Occurrence of Cyanobacterial Harmful 

Algal Blooms Workgroup Report 

Edited by Anthony Fristachi and James L Sinclair 

Workgroup Co-Chairs: 

James L Sinclair, Sherwood Hall

Workgroup Members1: 

Julie A Hambrook Berkman; Greg Boyer; JoAnn Burkholder; John

Burns; Wayne Carmichael; Al DuFour; William Frazier; Steve L Morton;

Eric O’Brien; Steven Walker 

Acknowledgements 

Appreciation is given to all those whose efforts made the production of 

this book possible. Thanks are due to the editors, Anthony Fristachi, US 

Environmental Protection Agency, Office of Research and Development, 

Cincinnati, Ohio and Jim Sinclair, PhD, US Environmental Protection 

Agency. Thanks are also due to Dr. Jeffrey Johansen of John Carroll University for his review and revisions to the Section 4 discussion of the current status of taxonomy of cyanobacteria. 

Special thanks to the workshop co–chairs: Jim Sinclair, PhD, US Environmental Protection Agency, Office Water, Cincinnati, Ohio and Sherwood Hall, PhD, Food and Drug Administration, CFSAN, Laurel, Maryland, who co–managed the process of preparing the manuscript. 

 

1 See Workgroup members and affiliations in Invited Participants section. 

Published in Cyanobacterial Harmful Algal Blooms: State of the Science and Research Needs,

ed. H. Kenneth Hudnell (Springer, 2008).
Invited Participants 

Occurrence Workgroup 

Workgroup Members 

Sherwood Hall, Co-chair 

US Food & Drug Administration 

shall@cfsan.fda.gov 

301-210-2160 

Jim Sinclair, Co-chair 

USEPA 

Sinclair.james@epa.gov 

Gregory L Boyer 

College of Environmental Science and Forestry 

State University of New York 

glboyer@esf.edu 

315-470-6825 

Julie Berkman 

US Geological Survey 

jberkman@usgs.gov 

614-430-7730 

JoAnn M Burkholder 

Center for Applied Aquatic Ecology, 

NCSU 

joann_burkholder@ncsu.edu 

919-515-3421

John Burns 

PBS&J 

jwburns@pbsj.com 

904-477-7723 

Wayne W. Carmichael

Wright State University 

wayne.carmichael@wright.edu 

937-775-3173

Al DuFour 

USEPA 

dufour.alfred@epa.gov

William Frazier 

City of High Point 

bill.frazier@highpointnc.gov 

336-883-3410 

Tony Fristachi 

NCEA CIN 

fristachi.anthony@epa.gov 

513-569-7144 

Steve Morton 

NOAA 

steve.morton@noaa.gov 

Eric O'Brien 

University of Iowa 

eobrien@igsb.uiowa.edu 

319-560-6128 

Steven Walker 

Nebraska Department of Environmental 

Quality 

steve.walker@ndeq.state.ne.us 

 402-471-4227 

Preface XV 
46 A. Fristachi and J.L. Sinclair

Introduction 

Freshwater cyanobacteria periodically accumulate, or bloom, in water bodies across the United States (US). These blooms, also known as cyanobacterial harmful algal blooms (CHAB), can lead to a reduction in the number 

of individuals who engage in recreational activities in lakes and reservoirs, 

degrade aquatic habitats and potentially impact human health. In 1998, 

Congress passed the 1998 Harmful Algal Bloom and Hypoxia Research 

and Control Act (HABHRCA) to address CHABs that impacted living marine resources, fish and shellfish harvests and recreational and service industries along US coastal waters. In 2004, as part of its reauthorization, 

HABHRCA requires federal agencies to assess CHABs to include freshwater and estuarine environments and develop plans to reduce the likelihood of CHAB formation and to mitigate their damage (NOAA 2004). 

Many federal agencies recognize the potential impacts of CHABs and 

share risk management responsibilities; an interagency task force was established and charged to prepare a scientific assessment of the causes, occurrence, effects and economic costs of freshwater. The United States Environmental Protection Agency (EPA) has included “cyanobacteria (blue–

green algae), other freshwater algae, and their toxins” in its Contaminant 

Candidate List (CCL) as one of the microbial drinking water contaminants 

targeted for additional study, but it does not specify which toxins should be 

targeted for study (EPA 2005b). Based on toxicological, epidemiology 

and occurrence studies, the EPA Office of Ground Water and Drinking 

Water has restricted its efforts to 3 of the over 80 variants of cyanotoxins 

reported, recommending that Microcystin (MC) congeners LR, YR, RR 

and LA, Anatoxin–a (AA) and Cylindrospermopsin (CY) be placed on the 

Unregulated Contaminant Monitoring Rule (UCMR) (EPA 2001). The 

EPA uses the UCMR program to collect data for contaminants suspected 

to be present in drinking water that do not have health–based standards set. 

This monitoring supplies information on the nature and size of populations 

exposed to cyanotoxins through tap water use. 

Various federal agencies are mandated to address CHABs and their impacts, which commonly have been managed on a case–by–case, somewhat 

fragmented basis. A new national US plan, the Harmful Algal Research 

and Response National Environmental Science Strategy (HARNESS), is 

“designed to facilitate coordination by highlighting and justifying the 

needs and priorities of the research and management communities and by 

suggesting strategies or approaches to address them” (HARNESS 2005). 

CHABs cross all four critical areas identified for harmful algal research 

and response: bloom ecology and dynamics; toxins and their effects; food 
Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 47 

webs and fisheries; and public health and socioeconomic impacts. 

HARNESS (2005) also noted that “research on freshwater harmful algal 

blooms [mostly formed by cyanobacteria] has lagged behind efforts to address marine harmful algal blooms [in general], and there is no comprehensive source of information on the occurrence and effects of freshwater 

harmful algal blooms in the US”. This is ironic, considering that CHABs 

have been documented to be highly responsive to nutrient pollution 

(Glibert and Burkholder 2006), and toxic to livestock, wildlife and humans 

in the US and worldwide (Chorus and Bartram 1999). 

This chapter will describe the occurrence of bloom–forming cyanobacteria and their toxins. Cyanobacteria water blooms are defined here as the 

visible coloration of a water body due to the presence of suspended cells, 

filaments and/or colonies and, in some cases, subsequent surface scums 

(surface accumulations of cells resembling clotted mats or paint–like 

slicks). They are a common occurrence in the US and throughout the 

world. Over 2000 species of cyanobacteria, many associated with nuisance 

blooms, are currently known (e.g. Komárek and Anagnostidis 1999, 

Komárek 2003). Freshwater HABs can assume many forms and while 

most are composed of prokaryotic cyanobacteria (blue–green algae), eukaryotic species may be present in blooms. While surface scums are commonly associated with blooms of Microcystis, blooms of other species 

such as Cylindrospermopsis in Arizona, Indiana and Iowa can be characterized by lower cell numbers events. Although not all blooms are characterized by high biomass events, high biomass blooms of toxic species/strains can have significant impacts on ecosystems by adding potentially large amounts of toxins (Glibert and Burkholder 2006). In addition, 

high–biomass blooms, whether of toxic or nontoxic species, also increase 

in oxygen demand during blooms and bloom decline, leading to localized 

hypoxia/anoxia and fish kills. These blooms can also cause habitat loss and 

food web changes. For example, surface blooms can block the light from 

reaching the benthos, leading to changes in attached plant communities 

and increased re–suspension of nutrients from the sediments. High–

biomass blooms also commonly lead to economic loss through their negative impacts on recreation activities, and tourism and their production of 

substances that cause taste–and–odor problems and increased treatment 

costs in potable water supply plants. Blooms of all types can lead to a decreased quality of life by causing a negative perception of the state of 

health of the water body. 

Multiple interacting physical, chemical and biological factors lead to the 

formation of CHABs. Planktonic cyanobacteria are a natural component 

of the phytoplankton in most surface waters of the world. Toxigenic spe- 
48

cies (capable of producing toxins, although not all populations or strains 

do so) are all naturally occurring members of freshwater and sometimes 

brackish water phytoplankton. The toxins that they produce can be compared with other naturally produced toxins (Carmichael 1992). Since the 

first report of toxic cyanobacteria in the late 19th century, all continents 

except Antarctica have reported toxic blooms (Carmichael 1992). Toxic 

blooms can be especially problematic and are characterized by their production of hepatotoxins, neurotoxins and acute dermatotoxic compounds 

(Chorus and Bartram 1999). In the US, blooms of cyanobacteria have 

been associated with the death of both wildlife and domestic animals 

(Carmichael 1998). To date, no human fatalities in the US can unambiguously be attributed to cyanobacterial toxins, though in at least one instance, 

this connection has been made in the popular press (Behm 2003; Campbell 

and Sargent 2004). Human health effects within the US have primarily included gastrointestinal illness in Pennsylvania (Lippy and Erb 1976), 

swimmers itch in Florida and Hawaii (Williams et al. 2001) and skin 

rashes, nausea, and other gastrointestinal disorders in Nebraska (Walker 

2005). In Brazil, a gastroenteritis epidemic was associated with the construction of the Itaparica Dam in Brazil (Teixeira et al. 1993), and the hospitalization of 140 children when supplied with drinking water from a reservoir containing a bloom of Cylindrospermopsis raciborskii in Australia 

(Chorus and Bartram 1999). The use of cyanotoxin–contaminated water in 

dialysis equipment in Brazil accounted for the only reported human fatalities (Carmichael et al. 2001a; Azevedo et al. 2002). 

Distribution of CHABs across the US 

Blooms in freshwater environments 

Freshwater CHABs are ubiquitous throughout the US and Canada (Fig. 1). 

Cyanobacteria perform many roles that are vital for the health of ecosystems, especially as photosynthetic organisms, but they may also cause 

harm through either excessively dense growth or release of toxins or other 

harmful metabolites. CHABs span habitats ranging from smaller eutrophic 

prairie ponds to larger more oligotrophic regions of the Great Lakes. This

ad distribution of potential

broad distribution is expected given the considerable diversity in habitats

occupied by cyanobacteria and the widespre

toxicity in the more common genera. 

A. Fristachi and J.L. Sinclair
Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 49 

Blooms in estuarine and marine environments 

While toxigenic cyanobacteria are generally associated with freshwater 

blooms, there is increasing recognition that, in certain regions of the world, 

blooms in estuarine and marine environments may also have an important 

impact on human health. The Baltic Sea and the Gulf of Finland often sustain massive blooms of toxic Nodularia spumigena that are easily visible 

in satellite images of the region (Sivonen et al. 1989). These blooms affect 

the natural biota and can spoil recreational opportunities on the coastline. 

Similarly, large blooms of benthic cyanobacterium Lyngbya majuscule in 

Moreton Bay, Australia (Albert et al. 2005), and off the Hawaiian Islands 

(Moikeha and Chu 1971; Moikeha et al. 1971) have caused skin, eye and 

respiratory effects on recreational users of these waters. Not all detrimental effects are directly associated with toxins; for example, increased 

cyanobacterial biomass in Florida Bay and other estuaries has been associated with sea grass die–offs and the decline of the adjacent coral reef systems (Williams et al. 2001). 

Both Microcystis aeruginosa and Cylindrospermopsis raciborskii have 

only limited tolerance to salinity (< 2–7 ppt) and this may limit the growth 

of these common toxic species in brackish waters environments (Barron et 

al. 2002). Increasing salinity in oligohaline and mesohaline estuaries results in increased osmotic stress and aggregation of cyanobacterial cells 

(Sellner et al. 1988). Many cyanobacterial species rapidly drop out from 

phytoplankton assemblages as salinity concentrations exceed their thresholds and thus are limited to freshwater tidal portions of these major rivers 

(Sellner et al. 1988). Nevertheless, increased freshwater inputs into rivers 

from increased runoff dilute the estuarine environment and can promote 

blooms of these toxic cyanobacterial (Sellner et al. 1988). For example, 

Lehman et al. (2005) recently documented a large bloom of M. aeruginosa 

in the upper San Francisco Bay Estuary. The bloom was widespread 

throughout 180 km of waterways; microcystins were detected at all stations sampled, and were also found in zooplankton and clam tissues. 

Other species of toxigenic cyanobacteria readily bloom in full salinity 

conditions and can dominate these environments. Non–toxic Aphanizomenon flos–aquae and toxic Nodularia spumigena form high biomass blooms 

in the Baltic Sea, and have increased in abundance (Sivonen et al. 1989; 

Finn et al. 2001). Anabaena (Aphanizomenon) aphanizomenoides occasionally has been reported to be abundant in the Neuse Estuary in North 

Carolina (Lung and Paerl 1988). 
50

Changes in the Distribution of Toxic Cyanobacteria 

In considering long–term trends of both the frequency of occurrence and 

distribution of cyanobacterial toxins in the US and Canada, it is important 

to recognize the remarkable advances that increased interest and awareness 

that has brought to the discipline over the last few decades. Both the number of known cyanobacterial toxins and toxigenic species has dramatically 

increased with the increased focus. While few, if any, states had monitoring programs for cyanobacterial toxins in the mid 1970’s in most cases, 

toxic cyanobacteria were identified as being responsible for livestock or 

wildlife fatalities. By 2005, a number of states had monitoring programs 

in place, resulting in an increase in the number of CHABs reported. It is 

difficult to determine if this increasing number of reports represents an increased incidence of CHABS, or is simply a reflection of increasing 

awareness and monitoring efforts. 

Several geographical regions have recently introduced “regional” surveys for the occurrence of cyanobacterial toxins. These regional studies 

have documented that the occurrence of cyanobacterial toxins has expanded outside of the midwestern prairie states (Fig. 3, see Color Plate 1). 

Studies in New York, Nebraska, New Hampshire and Florida have shown 

an increase in the abundance of cyanobacterial blooms. Sasner et al. studied 50 New Hampshire lakes and reported that all had detectable levels of 

microcystins (Sasner Jr. et al. 1981). Particulate concentrations of microcystins in the bloom spanned over four orders of magnitude and ranged 

from 0.8 to 31,470 ng/g-1 wet weight; concentrations were generally higher 

in the summer than in the spring. In a similar study of 180 New York 

lakes and rivers, over 50% of the samples contained easily detectable levels of particulate microcystins in the water column, ranging from 0 to over 

1000 μg/L (Boyer et al. 2004). Results of a short–term occurrence study 

by Carmichael et al. (unpublished 2006) in the Pacific Northwest states of 

Washington, Oregon and Northern California (Fig. 4, see Color Plate 1), for 

the years 2002–2005, show that producers of microcystin and anatoxin–a 

occur on regular basis. 

In warmer climates, both the intensity and duration of these bloom 

events increase. For example, cyanobacterial blooms are common in Florida lakes, rivers, streams and ponds; data has been collected on a limited 

basis since 1999. Approximately 20 bloom–forming cyanobacteria, including Microcystis, Cylindrospermopsis, Anabaena, Aphanizomenon, 

Lyngbya and Planktothrix, are found distributed throughout the state with 

cyanotoxins detected in surface waters and post–treated drinking water 

(Williams et al. 2001). 

A. Fristachi and J.L. Sinclair
Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 51 

Microcystin concentration was most often detected within the 0.1 to 10 

g L-1 range with a maximum concentration of 107 μg L-1; detected in 

post–treated drinking water at a maximum concentration of ~10 μg L-1 

(Burns 2005). Anatoxin–A was not detected in most samples collected, 

but a maximum concentration of 156 μg L-1 was detected in one sample; 

detected in post–treated drinking water at ~10 μg L-1. Cylindrospermopsin 

was detected between 10 and 100 μg L-1 (Burns 2005). The maximum cylindrospermopsin concentration detected in surface waters was 202 μg L-1. 

The maximum concentration of cylindrospermopsin detected in post–

treated drinking water was ~100 μg L–1 (Burns 2005). The first report of 

cylindrospermopsi in North America is mapped in Fig. 5. 

While there is some evidence for seasonal changes in CHABS occurrence (Graham et al. 2004), overall there is a paucity of data related to the 

temporal distribution of CHABs. 

Do invasive species change the occurrence of toxic species? 

Zebra mussels and Lake Erie (Vanderploeg et al. 2001)

The Great Lakes and especially Lake Erie have experienced many 

problems with invasive species over the past 100 years. The dreissenid zebra mussel, Dreissena polymorpha established itself in

Lake Erie in the late 1980’s and by 1995 blooms of the toxic cyanobacterium, Microcystis aeruginosa had become a problem. Studies

done since the late 90’s have led to the conclusion that zebra mussel 

selectively filtrate toxic Microcystis aeruginosa, promoting toxic

Microcystis blooms. This has resulted in new efforts to understand 

and control CHABs in the Great Lakes. 

s

μ
52

Fig. 1. Distribution of Documented CHAB outbreaks in North America. Unpublished data (Carmichael 2006). 

A. Fristachi and J.L. Sinclair
Fig. 2. Countries Reporting One or More CHAB Outbreaks. Unpublished data (Carmichael 2006). 

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 53 
Fig. 3. Trends in Microcystin Occurrence in Midwestern Lakes. Taken from

Graham et al. 2004. (See Color Plate 1). 

Fig. 4. Cyanotoxin Events in the Pacific Northwest (2001–2005). Taken from 

Carmichael 2006. (See Color Plate 1). 

54 A. Fristachi and J.L. Sinclair
Fig. 3 (Chapter 3). Trends in Microcystin Occurrence in Midwestern Lakes. 

Taken from Graham et al. 2004. (See page 54). 

Fig. 4 (Chapter 3). Cyanotoxin Events in the Pacific Northwest (2001–2005). 

Taken from Carmichael 2006. (See page 54). 

Color Plate 1 
Fig. 5. Florida Distribution of Cylindrospermopsin. (Williams et al. 2001). 

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 55 
Cyanotoxin Production 

The taxonomy of cyanobacteria, often imprecise, is currently under a state 

of revision. In general, cyanobacteria cells may be unicellular or filaments, existing singularly or in colonies. Morphological features can be 

distinct or variable, which has lead to considerable uncertainty when using 

the botanical taxonomic system that is based on morphological characteristics. For example, an early guide by Geitler (1932) and others listed more 

than 2000 species of cyanobacteria. Drouet and Daily, in a series of 

monograms published in the 1950s and 1960s (e.g. Drouet and Daily 1956; 

l957; Drouet l968), revised this flora using only the simplest of markers to 

lump everything together in only 62 species. Other taxonomists such as 

Stanier (1971), Castenholz (1992) and others proposed a taxonomic 

scheme for cyanobacteria based not on the botanical system, but using the 

provisions of the International Code of Nomenclature for Bacteria 

(Lapage et al. 1992). This system uses axenic clonal cultures and morphology as well as modern molecular and biochemical techniques to define 

the species. Despite the age of these proposals, only one taxon of cyanobacteria is currently described under the International Code of Nomenclature of Prokaryotes or ICNP (Euzeby 2004). Bergey’s Manual of Systematic Bacteriology contains only a few of the many described cyanobacterial 

genera, and no species. Recently, Castenholz (2001) reversed his earlier 

position and stated “I believe that the current rules of Nomenclature (botanical and bacteriological) should be mostly disregarded” and indicated 

that he preferred a moratorium on naming any species or undertaking any 

taxonomic revisions for 50 years or more so that molecular data sets could 

accrue (Hoffmann 2005). 

The botanical system for cyanobacteria has recently been revised using 

traditional morphological characters resulting in a major revision of species, especially for the non–heterocystous filamentous forms such as Oscillatoria (Komárek and Anagnostidis 1999, 2005). The revised system resurrects many of the older botanical names for genera. While cell structure 

and ultrastructure (thylakoids, cell wall formation, cellular dimensions) 

and molecular data have been congruent, sheath characteristics, which are 

critical in definition of both species and genera, are not always congruent 

with the molecular data. Unfortunately, ultrastructure, biochemical, and 

molecular studies, such as RAPD fingerprinting and 16S rRNA gene sequences are only available for a small portion of cyanobacterial taxa. 

56 A. Fristachi and J.L. Sinclair
The ecological diversity observed in cyanobacteria is grossly underestimated if one looks only at those taxa in culture collections (the taxa which 

are the source of the molecular and biochemical data). In some cases, molecular sequencing produces similar phylogenies. However, it is also quite 

easy to generate quite distinct phylogenetic lineages, depending on the particular part of the genome or trait that was used to generate the phylogeny. 

Most field taxonomists still rely on the traditional morphology–based botanical approach because molecular data have not yet been available for 

many species (Burkholder 2002), although the use of molecular based 

techniques is rapidly increasing, especially in those species that lack or 

contain confusing morphological features. Fortunately, toxic cyanobacteria have received concentrated attention, and so the taxonomy of these taxa 

may be among the first to be revised based on polyphasic character sets. 

Toxic cyanobacteria blooms are associated with a wide diversity of species and environments. Chorus and Bartram (1999) (1999), in their classic 

monogram for the World Health Organization, Toxic Cyanobacteria in 

Water: a Guide to Their Public Health Consequences, Monitoring and 

Management, reviewed which species of cyanobacteria have been associated with the production of toxins based on observations and reports since 

the mid 1980’s. Since that time, there have numerous new observations, 

including new toxigenic species such as the unknown Stigonematales species responsible for avian vacuolar myelinopathy (AVM) and new toxins 

such as

of species. Phormidium sp., which produces microcystin, has been found 

in shallows of reservoirs. Microcystin LA is reported to account for the 

protein phosphatase inhibitory activity of the terrestrial cyanobacterium, 

Hapalosiphon hibernicus. Other terrestrial isolates produce the toxin β–

methylamino alanine (BMAA). With the recent report of microcystins 

from lichen–associated Nostoc, it becomes apparent that non–aquatic environments must also be considered when discussing cyanobacterial toxicity. 

Table 1 lists 22 genera and 42 species associated with toxin formation. 

Most of the data was obtained from planktonic environments, although 

there are a number of toxic benthic species. Where appropriate, we 

have updated the nomenclature to the taxonomic scheme of Komárek 

and Anagnostidis (Komárek and Anagnostidis 1999, 2005). 

β–N–methylamino alanine (BMAA) produced by a wide number 

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 57 
Table 1. Major Toxigenic Cyanobacteria Species, their Toxins and Distribution. 

Organism Toxin Location Reference 

Anabaena spp. microcystins 

anatoxin–a 

Denmark, Egypt, Finland, Germany, Ireland, Japan, US

A. circinalis microcystins 

saxitoxins 

Finland, France, Australia 

A. flos–aquae microcystins 

anatoxin–a 

Canada, Finland, Norway, Canada 

A. lemmermannii microcystins 

saxitoxins 

Finland 

A. planktonica anatoxin–a Italy A. variabilis BMAA US Aphanizomenon spp. anatoxin–a Finland, Germany A. (flos–aquae) issatschenkoi saxitoxins US A. flos–aquae anatoxin–a(s) Canada A. gracile LPS endotoxins US A. lemmermannii saxitoxins 

anatoxin–a(s) 

Portugal, Denmark 

A. ovalisporum cylindrospermopsin Israel Arthrospira fusiformis microcystins Africa, Spain Anabaenopsis millerii microcystins Greece 

58

A.FristachiandJ.L.Sinclair
Organism Toxin Location Reference 

Cylindrospermum spp. anatoxin–a Finland Cylindrospermospis raciborskii, C. phillipinensis saxitoxins cylindrospermopsin 

BMAA 

Brazil, Australia, Hungary, US, Australia 

Haphalosiphon hibernicus microcystins US Ly

n

gbya spp. pahayokolide–a US 

L. majuscula BMAA Africa, Australia, US, Pacific Is. L. wollei (Plectonema wollei) Farlowe ex 

Gomont

dermatotoxins saxitoxins 

US 

Microcystis spp. microcystins 

anatoxin–a BMAA 

Worldwide 

M. aeruginosa microcystins Worldwide M. viridis microcystins Japan M. botrys microcystins Denmark Nodularia spumigena nodularins Canada N. spumigena nodularins Australia, New Zealand, 

Baltic Sea 

Nostoc spp. microcystins Finland, England and US 

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 59 
Organism Toxin Location Reference 

BMAA 

Oscillatoria spp. anatoxin–a Finland, Scotland, Ireland 

and US 

O. brevis (Phormidium breve) (Kützing ex Gomont) Agnostidis et Komárek 

LPS endotoxins Switzerland 

O. limosa Agardh ex Gomont microcystins US O. nigroviridis (O. nigro–viridis) Twaites ex. Gomont sensu Parakutty 

dermatotoxins US 

O. tenuis LPS endotoxins US Phormidium spp. microcystins 

BMAA saxitoxins 

US and Italy 

Planktothrix P. agardhii 

microcystins, anatoxin–a Microcystins BMAA 

US, Finland Denmark, Finland, Norway, Ireland 

P. flavosum anatoxin–a France P. formosa* homoanatoxin–a 

Norway 

P. mougeotii* (P. isothrix) (Skuja) Komárek and Komarkova 

microcystins Denmark 

Plectonema sp. BMAA Unknown origin Prochlorococcus marinus BMAA Sargasso Sea 

60 A. Fristachi and J.L. Sinclair
Organism Toxin Location Reference 

Raphidiopsis spp. R. curvata cylindrospermopsin 

anatoxin–a, 

R. mediterranea homoanatoxin–a 

Japan 

Schizothrix calcicola aplysiatoxins 

LPS (nontoxic) 

Pacific Islands and US 

Stigonematales sp. avm US Synechococcus sp. BMAA US Trichodesmium thiebautii BMAA 

saxitoxin 

Sargasso Sea 

Umezakia natans cylindrospermopsin Japan *denotes a species designation that is considered invalid using the current classification scheme 

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 61 
Cyanobacteria toxicity is very common in natural blooms with estimates of 

toxicity approaching as high as 50% (WHO 2003). In the late 1990s, in an 

attempt to systematically estimate the abundance of toxic cyanobacteria, 

approximately 200 strains of the Pasteur Collection of Cyanobacteria 

(PCC) were screened for microcystins using ELISA and HPLC–PDA 

techniques. G. Codd and R Rippka (unpublished) confirmed that more 

than 20 species produce cyanobacterial toxins, of which 11 strains of Microcystis and 1 strain of Nostoc produced concentrations of more than 100 

μg microcystins per gram dry weight (Boyer 2006). Many of the strains in 

the PCC have also been screened for the genetic potential for microcystin 

production using PCR techniques (Dittmann and Borner 2005). Similar 

results were also obtained from the NIVA culture collection in Norway, 

where a large percentage of the nearly 500 strains of cyanobacteria in the 

collection appeared to produce toxins or other bioactive substances 

(Skulberg 1984). Microcystin and harmful hepatotoxic peptides were produced by many, but not all strains of the cyanobacteria belonging to the 

genera Anabaena, Microcystis, Planktothrix and Nostoc (Hisbergues et al. 

2003). 

Toxigenic cyanobacteria are generally defined as species that have toxic 

strains (populations), which are capable of producing neurotoxic, hepatotoxic or dermatotoxic compounds (Burkholder and Glibert 2006). This 

term is important to note, since within a given species of toxigenic cyanobacteria, there commonly occur both toxic and nontoxic strains (Chorus 

and Bartram 1999; Burkholder and Glibert 2006). If one expands the definition of toxins to include bioactive peptides with protease inhibition activity such as the micropeptins, cyanopeptolins, microviridins, oscillapeptins, oscillamides, nostopeptins, aeruginosins, aeuginopeptins anabaenopeptilides, anabaenopepins and the cytotoxic compounds from marine 

origin, then the list of toxin–producing cyanobacteria species becomes 

quite large. Recently, the PCC were screened for the presence of non–

ribosomal peptide synthetase (NRPS) genes, those genes responsible for 

the synthesis of many bioactive peptides such as the microcystins, microveridins and anabaenapeptins (Christiansen et al. 2001). This biosynthetic activity is widespread throughout the cyanobacteria taxa, with NRPS 

activity found in over 75% of the 146 strains tested. While the presence of 

this gene activity does not directly correlate to toxicity, it indicates the potential for production of bioactive peptides. The non–ribosomal peptide 

synthetases used for microcystin toxin biosynthesis in cyanobacteria allow 

for considerable structural diversity (Christiansen et al. 2001). More than 

400 individual peptides have been identified, mostly from Anabaena, 

Lyngbya, Nostoc and Microcystis species (Krishnamurthy et al. 1986; 

62 A. Fristachi and J.L. Sinclair
Luesch et al. 2000; Pluotno and Carmeli 2005). Many of these peptides 

have protease inhibition activity and can lead to detrimental effects if consumed as part of the food web. 

In addition to the production of toxins, cyanobacteria have often been 

associated with the production of taste and odor compounds in with drinking water; the two most are geosmin and 2–methylisoborneol (MIB), although a number of different hydroxyketones and

also add to the off–flavors associated with freshwater cyanobacteria 

(Izaguirre and Taylor 2004). While these taste and odor compounds are 

not actually toxic, they are of concern to the consuming public when their 

drinking water has an “off” flavor, resulting in considerable monitoring 

and treatment costs to water supply providers. Taste and odor issues are 

complex and need not be associated solely with the presence of cyanobacteria. Many actinomycetes bacteria such as Actinomyces and Streptomyces

species, aquatic fungi such as Basidiobolus ranarum, and myxobacteria 

such as Nannocystis exedens can also produce these compounds (Niemi et 

al. 1982). Table 2 illustrates the large number of species associated with 

the production of compounds that affect taste and odor. These species may 

or may not be the same species reported to produce toxins. The biosynthetic pathways for taste and odor compounds are separate and unrelated to 

the toxin biosynthetic pathways (Carmichael 2001). 

β–ionone derivatives can

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 63
Table 2. Major Cyanobacterial Taste and Odor Producing Species. 

Organism

Com

pou

n

d

Anabaena spp. 

A. circinalis A. laxa A. macrospora A. scheremetievi A. spiroides A. viguieri

Geosmin 

Aphanizomenon 

flos–aquae Geosmin 

Calothrix sp. (C. parietina) Ketones, Ionones 

Fischerella muscicola Geosmin Jaaginema geminatum (Oscillatoria geminata) (Menehgnin ex Gomont Komárek and Anagnostidis 

MIB 

Ly

n

gbya spp. 

L. aestuarii (Lyngbya aestuarii) Liebman ex Gomont L. cryptovaginata (Planktothrix cryptovaginalt) (Škorbatov) Anagnostidis et Komárek

MIB Geosmin 

Oscillatoria spp. 

O. chalybea (Phormidium chalybeum) (Mertens ex Gomont) Anagnostidis  et Komárek O. raciborskii (Planktothrix raciborskii) (Woloszyńska) Anagnostidis et Komárek 

MIB 

O. agardii (Planktothrix agardhii) (Gomont) Anagnostidis et Komárek O. amoena (Phormidium amoenum) (Kützing 1843) Anagnostidis et Komárek O. amphibia (Geitlerinema amphibium) (Agardh ex Gomont) Anagnostidis O. bornetii (Tychonema bornetii) (Zuka) Anagnostidis et Komárek 

Geosmin 

64 A. Fristachi and J.L. Sinclair
Organism

Com

pou

n

d

O. brevis (Phormidium breve) (Kützing ex Gomont) Anagnostidis et Komárek O. variabilis (Oscillatoria variabilis) (Rao) O. prolifica (Planktothrix prolifica ([Grevelle] Gomont) Anagnostidis et Komárek 

O. simplicissima (Phormidium simplicissimum) (Gomont) Anagnostidis et Komárek O. splendida (Geitlerinema splendidum) (Greville ex Gomont) Anagnostidis 

O. cortiana (Phormidium cortiamum) (Meneghini ex Gomont) Anagnostidis  et Komárek O. curviceps Agardh ex Gomont O. limosa Agardh ex Gomont O. tenuis Agardh ex Gomont

Geosmin, MIB 

Phormidium sp. 

P. autumnale (Phormidium autumnale) [Agardh] Trevisan ex Gomont P. calcicola (Phormidium calcicola) Gardner P. tenue (Phormidium tergestinum) (Kützing) Anagnostidis et Komárek

Geosmin Geosmin, MIB MIB 

Plectonema sp. 

P. notatum (Leptolyngbya notata) (Schmidle) Anagnostidis et Komárek 

Ketones, Ionones 

Pseudanabaena catenata 

P. catenata P. limnetica (Oscillatoria limnetica) (Lemmermann) Komárek and Anagnostidis

MIB 

Rivularia spp. Ketones, Ionones Schizothrix muelleri

(Symplocastrum muelliri) (Nägeli ex Gomont) Anagnostidis 

Geosmin 

Symploca muscorum Gomont ex Gomont Geosmin Tolypothrix distorta Ketones, Ionones 

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 65 
Cyanotoxin Occurrence and Distribution 

Cyanobacterial toxins fall into several diverse categories and are usually 

divided based on their biological activity (hepatotoxins versus neurotoxins) 

or chemical structure (peptide toxins versus alkaloids) (Table 3). This division is becoming more complicated as new toxins are being identified. 

For example, in 1988, there were 10 reported microcystins; as of 1998, 

there are over 60 different chemically identified microcystins (Chorus and 

Bartram 1999). In the sections below, we summarize the basic classes of 

cyanobacterial toxins, their source organisms and their biological effects. 

Microcystins 

As shown in Table 1, microcystins have been reported in Microcystis, 

Anabaena, Oscillatoria, Planktothrix, Nostoc, Hapalosiphon and Anabaenopsis with new sources appearing yearly (Huisman and Hulot 2005). 

Microcystins (Fig. 6) contain 7 amino acids in their cyclic peptide ring system, are closely related to nodularin (Fig. 7) or nodulapeptins, which have 

5 amino acids in the ring system, as well as anabaenopeptins, aeruginopeptin and other bioactive peptides (Sivonen and Rapala 1998; Harada 

2004). Most of these peptides are hepatotoxins, though their LD–50 depends on the specific amino acids present. 

66 A. Fristachi and J.L. Sinclair
Adda

Arginine MeAsp (iso)

Leu

D-Glu (iso) Methyl dehydroAla (Mdha)

O D-Ala

NH

NH

O

NH

CH3

CO2H

H3C

CO2H

CH3 CH3

N

O NH

O

CH3

O

O NH

NH

NH2

NH

CH3

CH3

CH2

OCH3

CH3

S S

R

R

R

S

S

2

1

Fig. 6. The generic structure of a microcystin. 

Variations occur primarily at positions 1 and 2. For example, microcystin–LR contains the amino acids leucine (L) and arginine (R) at positions 1 and 2 respectively; microcystin–RR has arginine at both positions. 

Nodularins are similar with the five amino acids Adda–γGlu–Mdhb–

βMeAsp–Arg making up the core ring system (Harada et al. 1996). 

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 67
Table 3. Commonly observed cyanotoxins in US fresh, estuarine and marine waters. (adapted from Codd et al. 2005). 

Toxin Type and (# congeners) Mode of Action Hepatotoxins Microcystins Cyclic heptapaptides (>70) Protein phosphatase inhibitor, tumor promoter Nodularins Cyclic penta–peptide (9) Protein phosphatase inhibitor, 

Cylindrospermopsin Guanidine alkaloid (3) Protein synthesis inhibitor, genotoxic and necrotic injury to liver and other organelles. Neurotoxins 

Anatoxin–a azobicyclic alkaloid (5) Postsynaptic neuromuscular blocking agent and Acetylcholinesterase agonist Anatoxin–a(S) Guanidine organophosphate (1) Acetylcholinesterase inhibitor Saxitoxin Carbamate alkaloid (>20) Sodium channel blocker Β–methylamino alanine Modified amino acid 

Neurodegenerative agent

Dermatotoxins 

Lyngbyatoxin–a Indole Alkaloid (1) Inflammatory agent and Protein Kinase C activator Aplysiatoxin Polyacetate Alkaloid (2) Inflammatory agent and Protein Kinase C activator Endotoxins Lipopolysaccharides Lipopolysaccharides Gastrointestinal irritants 

68 A. Fristachi and J.L. Sinclair
Fig. 7. The generic structure of a Nodularin. 

Cylindrospermopsin 

Anatoxin–a 

The neurotoxic cyanobacterial toxins consist of anatoxin, anatoxin–a(S), 

saxitoxin and related analogs. The most important of these compounds 

Separate from the hepatotoxic cyclic peptides is the hepatotoxic alkaloid 

cylindrospermopsin (Fig. 8a). This toxin is usually produced by Cylindrospermopsis raciborskii and an outbreak of this organism in the drinking 

water supply on Palm Island, Queensland Australia led to a severe outbreak of hepatoenteritis among the inhabitants of the island (WHO 2002). 

Cylindrospermopsin has also been reported from Umezakia natans in 

Japan, Aphanizomenon ovalisporum in Israel (Sivonen and Jones 1999), and

Raphidiopsis Curuata in China (Li et al., 2001). It was generally assumed 

that the toxigenic cylindrospermopsin–forming species only bloomed in 

tropical and arid environments and Cylindrospermopsis raciborskii blooms 

are commonplace in the warmer Florida drinking water reservoirs. Increasing reports of C. raciborskii occurring in temperate zones of Europe and 

the U.S have been documented (Padisak 1997). Cylindrospermopsin–

producing blooms can be both high and low–biomass events, leading to 

difficulties in identifying the source of this toxin. 

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 69 
from an environmental health aspect is probably anatoxin–a (Fig. 8b) 

(Carmichael et al. 1975). Anatoxin–a was originally isolated from Anabaena flos–aquae (Devlin et al. 1977), but is also reported in A. planktonica, Oscillatoria spp., Planktothrix spp., and Cylindrosperum. Homoanatoxin–a, a toxic homologue with a propyl group replacing the acetyl 

group, was isolated from Phormidium (Oscillatoria) formosa. Both are 

potent nicotinic agonists and act as neuromuscular blocking agents. 

Anatoxin–a(S) 

Anatoxin–a(S) (Fig. 8c) is a naturally occurring organophosphate, with no 

reported structural variants, produced by Anabaena flos–aquae strain NRC 

525–17 and more recently by Anabaena lemmermannii (Henriksen et al. 

1997; Onodera et al. 1997). It is distinct from the neurotoxic anatoxin–a in 

both its chemical structure and biological mode of action (Mahmood and 

Carmichael 1986b). Anatoxin–a(S) acts as an acetyl–cholinesterase inhibitor and its name was derived from the fact that the intoxicated animals often suffered from extreme salivation (Matsunaga et al. 1989). Anatoxin–

a(S) is commonly reported in the prairie states of the US (Kenefick et al. 

1992); this may lead to an underestimate of its occurrence since, lacking a 

clear cyanobacterial source, death of livestock or pets from anatoxin–a(S) 

would likely be attributed to pesticide intoxication. 

Saxitoxins and related analogs 

Saxitoxins (STX) (Fig. 8d) are representative of a large toxin family referred to as the Paralytic Shellfish Poisoning (PSP) toxins. These include 

the N–1 hydroxysaxitoxin or neosaxitoxin (NeoSTX), 11–sulfate analogs 

of STX and NeoSTX called gonyautoxins (GTX) and 6 N21 sulfo derivatives of STX, neoSTX and GTX toxins B1, B2, C1 to C4 (Mahmood and 

Carmichael 1986a; Chorus and Bartram 1999). Not all of these 18 PSP 

analogs have been identified in marine dinoflagellates and shellfish. These 

toxins are identical to those produced by some toxigenic marine dinoflagellates that accumulate in shellfish that feed on those algae (Anderson 

1994). STX, neoSTX, C1, C2 and GTX have all been reported in freshwater cyanobacteria including Aphanizomenon spp., (Pereira et al. 2004, Li 

and Carmichael, 2003, Li et al. 2000) Anabaena circinalis,

wollei and a Brazilian isolate of Cylindrospermopsis raciborskii (Lagos

et al. 1999). 

Lyngbya

70 A. Fristachi and J.L. Sinclair
(a) cylindrospermopsin (b) Anatoxin–a 

(c) Anatoxin–a(S) (d) saxitoxin 

Fig. 8a–d. Structures of the alkaloid cyanobacterial toxins. 

–methylamino alanine (BMAA) 

A recently discovered cyanobacterial neurotoxin is non–protein amino acid 

β–N–methylamino–L–alanine (BMAA). BMAA, originally isolated from 

a Guam cycad, Cycas circinalis, has been implicated as the causative agent 

of amyotrophic lateral sclerosis or Parkinsonism dementia (Murch et al. 

2004b). Symbiotic Nostoc species associated with the roots of cycads produce BMAA and it accumulates in the seeds of the plant. The indigenous 

Chamorro people of Guam feed on the flying foxes, which consume these 

seeds, and are subject to a classic biomagnification of the toxin up through 

the higher trophic levels (Cox et al. 2005). BMAA may also be incorporated into peptides or proteins, both increasing its biomagnification and 

acting as a reservoir to slowly releasing toxins upon peptide hydrolysis 

(Murch et al. 2004a). 

Cox et al. (2005) surveyed 30 different strains of cyanobacteria obtained from culture collections that spanned the entire spectrum of cyanobacterial morphology and taxonomy for the presence of BMAA. Although 

BMAA is most common in Nostoc species, with 7 out of 10 isolates conβ

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 71 
taining high levels of either the free or protein–bound amino acid, it is 

ubiquitous in its distribution, being found in freshwater, marine, brackish 

and terrestrial environments. Only 1 of the 3 species tested, a freshwater 

Synechocystis species, lacked BMAA. Algal strains in culture often produce much lower levels of toxins than found in situ suggesting that there is 

potential for widespread human exposure to this toxin (Cox et al. 2005). 

BMAA was recently detected in the brains of nine Canadian Alzheimer patients, but was not found in the brains of 14 other Canadians that died from 

causes unrelated to neuro–degeneration (Murch et al. 2004a, 2004b). 

Since cycads are not part of the normal Canadian flora, cyanobacteria may 

be the source of BMAA in these patients. Drinking water contaminated by 

cyanobacterial blooms has been suggested as a potential pathway for human exposure to BMAA and a topic of future data needs. 

Lyngbyatoxins, Aplysiatoxin and Debromaplysiatoxin. 

Lyngbyatoxins, contact irritants, are mainly marine water toxins but their 

occurrence in freshwaters has not been fully assessed. Lyngbya, an aggressive genus capable of widespread growth, has been found in freshwater supplies in the US. Lyngbya blooms are common in Florida, forming

mats in freshwater springs and overgrowing some coastal reefs, where low 

levels of Lyngbya–toxin–A, debromoaplysiatoxin and saxitoxin have been 

detected (Williams et al. 2001). More data are needed to determine its 

health effects and occurrence in freshwater supplies. The inflammatory activity of Lyngbya is caused by aplysiatoxin and debromoaplysiatoxin, 

which are tumor promoters and protein kinase–C activators (Berry et al. 

2004). Debromoaplysiatoxin along with other toxic compounds has also 

been isolated from other members of the family Oscillatoriaceae such as 

Schizothrix calcicola and Oscillatoria nigroviridis (Chorus and Bartram 

1999). 

Other Bioactive Compounds 

Many cyanobacteria including Microcystis, Planktothrix and Anabaena

species have the ability to produce cyclic and linear peptide protease inhibitors that are potentially toxic (Harada 2004). Examples of these compounds include the micropeptins, cyanopeptolins, microviridin, oscillapeptin, oscillamide, nostopeptin, aeruginosins, aeruginopeptins, anabaenaopeptilides, anabaenopeptins and circinamide (papain inhibitor). 

Two such compounds isolated from Microcystis aeruginosa, aeruginopept72 A. Fristachi and J.L. Sinclair
ins and cyanopeptolins, are shown in Fig. 9. The effects of these compounds on the toxicity of cyanotoxins is not well known. 

aeruginopeptin 228–a

cyanopeptolin–a

Fig. 9. Structures of two bioactive peptides isolated from Microcystis aeruginosa. 

Impacts on Waterbody Health and Ecosystem Viability 

The factors that lead to CHAB formation and induce toxin production are 

not well known (Chorus and Bartram 1999). Although multiple studies 

have examined the empirical relationship between environmental variables 

and toxin concentrations, few have measured the many different variables 

necessary to compile a comprehensive data set for analysis, (Kneale and 

Howard 1997). Even fewer have analyzed the data based on sound statistical methods recommended by EPA and other agencies (EPA 2003). Temporal and spatial patterns of CHAB formation are often complex, and the 

mechanisms of bloom progression are largely unexplained. Additionally, 

CHABs can include both toxic and non–toxic strains, and many strains can 

be present during CHABs in specific lakes (Vezie et al. 1998; Jacoby et al. 

2000; Pawlik–Skowronska et al. 2004). A major source of variation in 

toxin concentration appears to be the strain–dependant influence of enviChapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 73 
ronmental factors on toxin release (Rapala and Sivonen 1998; Vezie et al. 

2002) and successive replacement of toxic and non–toxic species 

(Kardinal and Visser 2005). No single modeling study has attempted to 

predict the dynamics of toxin releases and/or toxin levels, reflecting a limited understanding of factors influencing toxin release. 

Several recent reviews (Paerl 1996; Soranno 1997; Carmichael et al. 

2001b; Saker and Griffiths 2001; Landsberg 2002; Codd et al. 2005; Huisman and Hulot 2005). provide a comprehensive discussion of individual 

environmental factors that may be responsible for CHABs and their correlated effects on ecosystem health. Physical factors include temperature, 

light availability and meteorological conditions. Hydrologic factors include 

alteration of water flow, turbidity and vertical mixing. Chemical factors include nutrient loading (principally nitrogen [N] and phosphorous [P]), pH 

changes and trace metals, such as copper, iron and zinc. 

Freshwater Habitats 

Most of the world’s population relies on surface freshwaters as their primary source for drinking water. The drinking water industry is constantly 

challenged with surface water contaminants that must be removed to protect public health. Recent reports suggest that CHABs are an emerging issue in the US because of increased source–water nutrient pollution causing 

eutrophication. Although CHABs historically have been strongly correlated with nutrient over–enrichment in many freshwater lakes with low 

abiotic turbidity (e.g Schindler 1987, Whitton and Potts 2000), flowing 

waters can also develop planktonic CHABs in slowly flowing segments 

(e.g Pinckney et al. 1997). Intermediate systems – run–of–river impoundments or reservoirs – generally have faster flushing and higher abiotic turbidity from suspended sediment loads than natural lakes (Wetzel 2001). In 

these systems light, rather than nutrients, often is the most important resource limiting cyanobacteria growth (Cuker et al. 1990). In addition, because of the surface characteristics of their cells, cyanobacteria can be especially susceptible to being attracted to sediment particles (Avnimelech et 

al. 1982, Søballe and Threlkeld 1988, Burkholder 1992). When that occurs, they become too heavy to remain in the water column and settle out 

of the water column (Burkholder and Cuker 1991). Nevertheless, during 

intervals between episodic sediment loading events from land erosion and 

runoff, dense cyanobacteria blooms can develop in reservoir systems, and 

nutrients – both nitrogen and phosphorus – can become important in controlling their production (Touchette et al. (submitted), Cuker et al. 1990, 

Burkholder and Cuker 1991); Fig. 10. 

74 A. Fristachi and J.L. Sinclair
Many eutrophic lakes and impoundments (reservoirs) have documented 

CHAB problems, for example: The Metropolitan Water District of Southern California (MWDSC) has a long history of algal problems, in the form 

of planktonic blooms and benthic proliferations (Izaguirre 2005). The 

main concern is taste and odor, specifically the compounds geosmin and 

MIB. All of the reservoirs listed below have experienced algal blooms of 

one kind or another, including in some cases known toxigenic species. In 

addition, Lakes Mathews, Skinner, Perris and Diamond Valley have developed benthic mats that have resulted in severe off–flavor problems 

(Izaguirre 2005). MWDSC, is composed of 26 member agencies and supplies drinking water to about 18 million people in six counties in the 

coastal plain of southern California; its two sources of water are the Colorado River and water from northern California delivered through the California aqueduct feeding into three reservoirs in Riverside County: Lake 

Mathews, Lake Skinner and Diamond Valley Lake (Izaguirre 2005). In 

North Carolina, a large, previously undetected, sewer spill that occurred 

over several months was positively correlated with Lyngbya blooms 

(Frazier 2006). 

As research progresses, new toxins from cyanobacteria in freshwater 

systems are being discovered (Codd et al. 2001; Huisman and Hulot 2005), 

as well as new potential roles in their impacts on food webs. For example, 

avian vacuolar myelopathy (AVM), a neurological disease in waterfowl 

and their predators, was first described in the mid–1990s, with unknown 

cause (Thomas et al. 1998). AVM causes characteristic lesions in the myelin of the brain and spinal cord. Affected birds have abnormal flying and 

swimming because their muscle coordination is compromised. The causative agent of AVM is associated with submersed aquatic vegetation such as 

the aquatic weed hydrilla (Birrenkott et al. 2004). At present, the prime 

“suspect” is a toxin producing, yet unnamed cyanobacterium within the 

order Stigonematales that colonizes the leaves of hydrilla and other submersed plants (Wilde et al. 2005). Thus, the working hypothesis being examined is that waterfowl such as coots consume submersed vegetation 

covered with the toxic cyanobacteria, bioaccumulate the toxin(s), and are 

impaired in their ability to escape from predators. The affected waterfowl 

are caught and consumed by higher predators such as bald eagles, which 

then also develop AVM. 

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 75
0 50 100 150 200 250

0

8040

120 D. Old

(r2 = 0.81)

0 20 40 60 80

0

80604020

C. Mod.

(r2 = 0.48)

(μg/L) a Chl

TP (μg/L) TP (μg/L) 

0

80604020

140120100

200 400 600 800 1000 1200

0

80

604020

(μg/L) a Chl

A. Mod

(r2 = 0.65)

TN (μg/L) TN (μg/L) 

0 1000 2000 3000 4000 5000 

B. Old

(r2 = 0.48)

0 50 100 150 200 250

0

8040

120 D. Old

(r2 = 0.81)

0 20 40 60 80

0

80604020

C. Mod.

(r2 = 0.48)

(μg/L) a Chl

TP (μg/L) TP (μg/L) 

0

80604020

140120100

200 400 600 800 1000 1200

0

80

604020

(μg/L) a Chl

A. Mod

(r2 = 0.65)

TN (μg/L) TN (μg/L) 

0 1000 2000 3000 4000 5000 

B. Old

(r2 = 0.48)

Fig. 10. Relationship between chlorophyll a (chla) and total nitrogen (TN, upper panels) or total phosphorus (TP, lower panels). (A, 

C) moderate–age reservoirs (mod., Group 1, 20–30 years post–fill, n = 5) and (B, D) old reservoirs (Group 2, 60–85 years post–fill, n = 6) during summer months when cyanobacteria were dominant (Touchette et al. (submitted)). 

76 A. Fristachi and J.L. Sinclair
Estuarine Habitats 

Estuaries are comprised of high population densities of microbes, plankton, benthic flora and fauna. These organisms tend to be highly vulnerable 

to human activities and a wide array of human impacts that can compromise their ecological integrity. Many of the factors responsible for CHABS 

as well as the CHABs themselves affect estuarine habitat health. Anthropogenic stress in the form of increased nutrient input significantly impacts 

estuaries as well as other water bodies. Modeling studies suggest the importance of nutrient loading to water quality and CHAB probability and 

severity. Nitrogen (N) and phosphorus (P) enrichment are considered 

cyanobacteria bloom precursors. Many cyanobacteria are nitrogen–fixers, 

making N a limiting factor in competition over other phytoplankton species (Burkholder 2002). Although nutrient influences are widely studied 

factor linked to stimulation of CHABs, the nutrient(s) that are most important in limiting cyanobacteria growth are still in debate, and likely depend 

upon the habitat and history of nutrition (e.g. Lenes et al. 2001; Glibert et 

al. 2005, 2006). 

Cyanobacteria blooms were noted in the Potomac River and the upper 

Chesapeake Bay during the 1950s and 1960s coincident with the invasion 

of water milfoil. Since 1985, cyanobacteria blooms have been documented 

in the tidal tributaries of Chesapeake Bay almost annually during summer 

months by the Maryland Department of Natural Resources (MD–DNR) 

long–term comprehensive water–quality monitoring program. During September 2000, an extensive late summer bloom of Microcystis on the Sassafras River, however, was among the first blooms tested for cyanotoxins in 

Maryland and results were positive for elevated concentrations of microcystin. The microcystin levels (591.4–1041 g g-1 dry wt) led to the Kent 

County Health Department closing a public beach in the bloom area for the 

remainder of the year, the first beach closure in the history of the state due 

to detected levels of cyanotoxins (Tango et al. 2005). Dr. Harold Marshall, a renowned phytoplankton specialist in the Chesapeake Bay area, has 

also documented significant increases in cyanobacteria biomass, mostly as 

Microcystis aeruginosa, from long–term datasets in tributaries of lower 

Chesapeake Bay (Fig. 11). 

μ

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 77
Fig. 11. Long–term datasets (1987–2005) show increasing cyanobacteria biomass in tributaries of lower Chesapeake Bay. 

78

A.FristachiandJ.L.Sinclair
Marine Habitats 

In comparison to fresh and estuarine waters, relatively little is known about 

harmful cyanobacteria in marine ecosystems, except for their negative effects on coral reefs. For example, the toxigenic, benthic cyanobacterium 

Lyngbya majuscula proliferates in warm marine waters enriched with nutrients (especially phosphorus or iron) (e.g., Watkinson et al. 2005). Nicknamed “stinging seaweed” (Sims and Zandee Van Rilland 1981), L. majuscula produces an array of toxins that adversely affect human health

(Osborne et al. 2001) and have been implicated as causes of tumors and 

other diseases in marine fauna (e.g. Arthur et al. 2006). It also has caused 

serious ecological impacts in smothering coral reefs and seagrass meadows. For example, a recently described bloom expanded to 8 km2

 of coverage within 55 days, and its dense accumulation (average biomass 210 

grams dry weight · m–2) led to declines in beneficial seagrasses 

(Watkinson et al. 2005). As another example, the cyanobacterium Phormidium corallyticum is a member of a microbial consortium that causes 

black band disease and death of corals (Richardson 2005). 

Although cyanobacteria in many saltwater ecosystems have not been rigorously examined for toxicity, limited available evidence suggests that 

cryptic toxigenic species can be abundant in these habitats. For example, a 

survey of the landlocked, brackish to hypersaline, Salton Sea revealed that 

85% of all water samples tested from areas with high incidence of grebe 

deaths contained low but detectable levels of microcystins produced by picoplanktonic Synechococcus and benthic Oscillatoria (Carmichael and Li 

2006). Moreover, the livers of affected grebes contained microcystins at 

potentially lethal levels. 

Possible interactions between cyanobacteria and marine harmful algal blooms: Trichodesmum spp. are marine cyanobacteria that fix

nitrogen gas into inorganic nitrogen forms that are used to make proteins not only by the cyanobacteria, but by other organisms as nitrogen leaks from the cyanobacteria cells. The impacts are currently 

being explored and are not necessarily bad, but the added available 

nitrogen has been hypothesized to help support blooms of harmful 

algae such as Karenia brevis, the toxic ‘red tide’ organism of the 

Gulf of Mexico (Lenes et al. 2001, Glibert et al. 2006). This hypothesis is presently under debate (Hu et al. 2006). 

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 79 
Potential Chronic, Insidious Impacts on Human Health 

Present understanding about the effects of toxigenic cyanobacteria on human health are mostly limited to obvious, acute impacts, and thus do not 

include chronic, subtle or insidious impacts that are happening but not yet 

detected, and potential impacts where hazards exist in remote areas where 

health impacts have not yet been sustained. It is expected that the risk from 

cyanobacterial CHABs to drinking and recreational waters will increase 

with increased stress and demand on those systems (Glibert and 

Burkholder 2006) (e.g. Fig. 12, see Color late and Fig. 13, see Color

cluding the increase in population and its exposure to toxins, the requirement for new drinking water and recreational sources and the speed and 

extent with which effective management strategies are implemented. 

It is expected that the demand for drinking water in the US will increase 

dramatically in the future. Although many utilities in the US use underground water supplies, many also use surface water and that proportion is 

expected to increase in many areas (e.g. Martin 2001). Increasing population has placed increased demand on surface water supplies, either through 

their anthropogenic inputs or through their increased demand for drinking 

water. Conventional water treatment appears to be ineffective in removing 

cyanotoxins from drinking water (Hoeger et al. 2004, 2005); cyanobacterial cells lyse during filtration and chlorine does not appear to readily oxidize the resulting MC (Wannemacher Jr. et al. 1993; Hitzfeld et al. 2000). 

To control HABS, algaecides, especially copper sulfate, are commonly 

added to surface drinking water sources (Chorus and Bartram 1999), but 

this leads to cell lysis and a substantial release of cyanotoxins into the water, as well as potential copper toxicity (Kenefick et al. 1993). Powdered 

and granular activated carbon adsorption, with reported removal efficiencies of greater than 90%, removes toxins as well as intact cells and appears 

to be a more effective and reliable methods for removing cyanotoxins than 

Cl (Hamann et al. 1990; Donati et al. 1994). A similar increased in risk is 

also expected for recreational waters where, for humans, the primary route 

of exposure is oral from accidental or deliberate ingestion of recreational 

water, inhalation of aerosolized cells or from dermal contact. 

P 2

Plate 2). The magnitude of the threat will depend on many variables in80 A. Fristachi and J.L. Sinclair
OCCURRENCE OF CYANOBACTERIAL BLOOMS IN THE 

LAKE PONTCHARTRAIN ESTUARY, LOUISIANA 

Toxic cyanobacterial blooms have been reported in Lake Pontchartrain, an oligohaline lake bordering New Orleans, Louisiana. Lake Pontchartrain is a tidally influenced estuary that connects to the Mississippi River via the Bonnet Carré Spillway and to the Gulf of Mexico by the Rigolets strait, Chef Menteur Pass, and Lake Borgne. It represents the second largest salt–water lake in the US (1630 km2), after the Great Salt Lake in Utah, and the largest lake in Louisiana. 

Toxic cyanobacterial blooms (e.g., 

Microcystis & 

A

n

a

b

aen

a) have occurred on Lake Pontchartrain following the discharge of water from the Mississippi River to the estuary via the Bonnet Carré Bonnet Spillway. The spillway was constructed to divert floodwater through the lake before it reaches the city of New Orleans. The floodgate between the 

spillway and the river is only opened during severe flood events, but water can seep into the spillway through the closed gate (Lane et al. 2001). The seeping river water leaks brown clouds of sediment and nutrients into Lake Pontchartrain. When the floodgates have been opened in the past, the influx of fresh, nutrient–rich water has been followed by fish kills and toxic cyanobacterial blooms. 

The 1997 opening of the Bonnet Carré Spillway is one of the better–documented events where toxic cyanobacterial 

booms occurred on the lake following the release of water from the river to the lake (Dortch et al. 1998). The algal bloom became apparent over large parts of the lake during May and produced high levels of hepatotoxins, prompting health advisories by the Louisiana Department of Health and Hospitals. Fig. 12. Anabaena bloom on Lake Pontchartrain. 

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 81 
Fig. 12.

5 km N

~2.2 miles

Falls Lake, North Carolina

~16 miles

~16 miles

5 km N

~2.2 miles

Falls Lake, North Carolina

~16 miles

~16 miles

Fig. 13. Map of Falls Lake, NC, indicating six sampling stations and the location

of the intake for the water treatment plant of the capital city, Raleigh. 

is sustaining rapid human population growth and associated increased nutrient

runoff into receiving waters. From Burkholder (2006b). (See Color Plate 2).

The watershed

)

Burns. See Color Plate 2). 

82 A. Fristachi and J.L. Sinclair

(cont. Anabaena bloom on Lake Pontchartrain (Photo courtesy of John
Fig. 12 (Chapter 3). Anabaena bloom on Lake Pontchartrain (Photo courtesy of 

John Burns. See page 8 2). 

5 km N

~2.2 miles

Falls Lake, North Carolina

~16 miles

~16 miles

5 km N

~2.2 miles

Falls Lake, North Carolina

~16 miles

~16 miles

Fig. 13 (Chapter 3). Map of Falls Lake, NC, indicating six sampling stations and 

the location of the intake for the water treatment plant of the capital city, Raleigh. 

The watershed is sustaining rapid human population growth and associated 

increased nutrient runoff into receiving waters. From Burkholder (2006b). 

(See page 8 2). 

Color Plate 2 
Fig. 14. Total N, total P, chlorophyll a (indicator of algal/cyanobacterial biomass), 

and total N : total P ratios in Falls Lake plotted against distance downstream from 

the headwaters to the dam. 

The last station (intake) is the location of the intake for the City of Raleigh water treatment plant. About 75% of the phytoplankton cells in this reservoir during 

summer months are cyanobacteria, including various toxigenic species based on 

data from 2002–2005 (Burkholder 2006). The lower end of the reservoir where 

the water treatment plant is located presently has good water quality, but there is 

concern that as nutrient loading to the reservoir continues to increase, water 

quality will become more degraded throughout the reservoir and cyanobacteria 

will be further stimulated. 

Frequency and Severity Ranking. 

Both our exposure and our knowledge follow the hierarchy of frequency 

and severity freshwater > estuarine (brackish) > marine. While adverse impacts of cyanobacteria in eutrophic freshwaters and (less so) estuaries are known worldwide (Whitton and Potts 2000), impacts on marine 

ecosystems have only recently begun to be recognized. Thus, the indicated 

rankings may change as additional information becomes available. 

Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 83 
Data Needs 

To improve our ability to measure the incidence and predict the occurrence 

of CHABS, we need to make full use of existing information that is currently available through a variety of sources. State and regional investigators have conducted a number of surveys of cyanotoxins that needs to be 

compiled into a readily accessible database. Information that has been collected on the factors related to bloom occurrence should be compiled so 

that it can be related to toxin occurrence. This includes land use data, nutrient concentration in water, and weather conditions. Information on robust analytical methods for cyanobacteria and toxin quantification in environmental waters needs also needs to be compiled. 

Short—term Objectives 

Research Needs 

There is currently a lack of agreement on species level taxonomy for 

cyanobacteria. Because of this lack of agreement, cyanobacteria can only 

be identified easily to the genus level, which means that information may 

be lost in surveys when only genera are identified. Additionally, changing 

taxonomy can be a confounding factor for older surveys. Modern molecular techniques offer one solution to this problem but even these techniques 

require a consensus on the definition of toxigenic cyanobacterial species.

Considerable information on cyanobacterial species and their toxins is 

also available in non–traditional literature sources. A comprehensive literature survey, including the grey literature, is needed. Both planktonic 

and benthic cyanobacteria should be included in this survey. These and 

newer references need to be reviewed and summarized for occurrence of 

toxigenic species. A working bibliography on cyanobacteria compiled by 

the EPA can be found at http://www.epa.gov/safewater/ucmr/ucmr1/docs/ 

meetings_umcr1_cyanobacteria_references.doc. 

An improved understanding is needed of the environmental factors that 

are responsible for cyanobacterial growth and bloom formation. Additionally, a better understanding is needed of when cyanobacteria do and do not 

produce toxins, and factors responsible for production of toxins. This information can be obtained from both field studies and supporting laboratory experiments. Perhaps the best information currently available is for 

Microcystis aeruginosa; the genes involved in toxin production have been 

identified, and various environmental factors including light, nitrogen, 

84 A. Fristachi and J.L. Sinclair
Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 85 

phosphorus, and iron nutrient supplies have been shown to influence toxin 

production (Zurawell et al. 2005). 

Research is needed to determine the importance of very small (picoplanktonic) cyanobacterial species in the production of cyanobacterial 

toxins. Similar research is needed for many benthic species. Among the 

many questions that remain unanswered are: how significant are levels of 

toxins produced by planktonic and benthic species? How does their toxin 

production vary over time as compared to historically recognized bloom 

species? What kinds of toxins are produced by these cyanobacteria? 

BMAA originating from cyanobacteria on the roots of cycads has been 

reported to be associated with Alzheimer's disease in patients who have 

been exposed to BMAA from the food chain. Additional studies have detected BMAA in cyanobacteria from a variety of geographical locations 

(Cox et al. 2005). Because of the seriousness of Alzheimer's disease, plus 

the apparent widespread distribution of BMAA, research is needed to determine the occurrence of BMAA in water in the US, including the fate of 

this toxin during water treatment for drinking water production. 

The conventional wisdom for cyanobacteria is that cylindrospermopsin 

is released extracellularly from healthy cells, whereas other commonly occurring cyanotoxins are contained in healthy cells, and only released if 

cells are damaged or dying. Recent evidence suggests that this generalization may not hold in some situations; thus, research is needed to verify that 

how toxins typically are distributed in commonly occurring species. These 

studies should use more than one strain of each species, because as mentioned, within a given species of cyanobacteria are many nontoxic as well 

as toxic strains (Burkholder and Glibert 2006). 

Research is also needed to determine whether cyanotoxins are accumulated in the tissues of fish and shellfish. These studies should be done for 

the most important cyanotoxins which fish and shellfish are likely to be 

exposed to in both natural bodies of water as well as in aquaculture (e.g. 

nodularin in some estuarine/marine environments). The exposure of people to cyanotoxins originating from spray or aerosols should be investigated. 

Analytical Needs 

There is an immediate need for rapid techniques for both screening and 

confirmatory methods for the cyanotoxin analyses, including simple, inexpensive methods for rapid screening of samples during sampling of 

blooms. Different types of methods are needed for different applications 

and each must be targeted towards its end users. Several ELISA screening 
86

In addition to identifying the toxins, there is a need for additional tools 

targeted towards identifying a potentially toxigenic organism. Species–

specific and toxin–specific molecular probes, microarrays and other technology are needed for studies to determine the occurrence and distribution 

of potentially toxigenic cyanobacteria. To be most useful, these detection 

methods should be cost–effective, rapid and reliable. 

Standardized methods for quantifying cells and estimating biomass are 

also needed. These methods should be developed in conjunction with 

taxonomic identification methods, since identification of species may depend on characteristics that may be altered in some cell quantification 

schemes. When developed, these methods should be validated. Since cell 

count methods using microscopy generally are tedious and labor–intensive, 

alternate, accurate methods to determine cell density or biomass are 

needed, such as improved techniques to quantify photosynthetic pigments, 

total suspended solids or particulate organic carbon. Unfortunately, these 

methods at present all fall short of accurately estimating cyanobacteria 

biomass, and cannot provide information about toxicity or the dominant 

taxa involved. Improvements in technology are needed to rapidly track 

toxigenic species and formation of blooms. These technologies include 

remote sensing, remote–operated vehicles (ROVs) and automated sampling stations located on vulnerable bodies of water (Glasgow et al. 2004). 

Monitoring Needs 

There is an immediate need for a nation–wide survey(s) on the occurrence 

and distribution of toxigenic cyanobacteria and their toxins throughout the 

US. Some surveys of cyanobacterial toxins have been conducted; however, 

information on cyanotoxin occurrence is still fragmented and limited. Any 

information of cyanotoxin occurrence is useful, but in particular, national 

A. Fristachi and J.L. Sinclair

methods are available for microcystins, but none are currently manufactured for cylindrospermopsin and other toxins anatoxin–a. On–line detectors would be useful for water utilities for continuous monitoring; instrumental methods are needed for use where quantitation and specificity are 

important. Methods including LC/MS and LC/MS/MS have been developed, but none have been accepted as validated US EPA methods or 

consensus organization methods. There is a need for standardized instrumental methods that can be run by commercial labs. Many of the instrumental methods for cyanotoxins are dependent on sample cleanup methods 

that remove interfering substances. To be successful, these methods must 

perform in a wide variety of water types, including those with high levels 

of total organic carbon. 
Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 87 

surveys, consistently conducted, are needed to assess cyanotoxin occurrence on a larger scale. 

The US EPA is planning to conduct a national survey of drinking water 

for cyanotoxins, under its Unregulated Contaminant Monitoring Rule 

(UCMR) when the suite of analytical methods needed becomes available. 

Monitoring will occur for one year at approximately 2,800 large public water systems (PWS) and a representative sample of 800 (out of 66,000) 

small PWS. Transient water systems are not required to monitor nor are 

systems that purchase 100% of their water (EPA 2005a). The monitoring 

results from these systems will be used to form an initial nationally representative occurrence assessment of the most commonly occurring 

cyanotoxins in the US. A similar survey is needed for ambient water 

sources, including recreational and agricultural water. Currently, no program exists for conducting this kind of survey, which should include both 

randomly selected locations as well as targeted locations where blooms 

historically have been reported, or are reported to be in progress. This design would assure that both typical occurrences and unusual bloom events 

would be considered and could be used to determine risk to exposed people or animals. 

In many locations in the US, cyanobacterial blooms are common events. 

Nevertheless, they can be sporadic in occurrence and difficult to predict. 

Even targeting locations that recently have experienced blooms may not 

mean that blooms will occur in these areas in the future; on the other hand, 

in developing watersheds blooms may begin to develop in previously 

“bloom–free” locations. Undetected or missed blooms would result in an 

underestimate of the risk of exposure. A central reporting website needs to 

be established to assist in documenting blooms. This website needs to be 

publicized to utility operators, state department of environmental quality 

officials and others who would be aware of blooms as they occur. These 

reports would allow researchers who have the ability to analyze water 

samples for cyanotoxins to sample these events while they are occurring. 

Long—term Objectives 

Research Needs 

As a longer–term project, an easily accessed database (i.e. website) on the 

historic occurrence of toxigenic strains is critically needed, including user–

friendly summaries for the general citizenry. This could be incorporated 

into a national database of toxin occurrence data that can be routinely updated. Currently, there is no central location for cyanotoxin data produced 
88

by states or other organizations. Long–term monitoring needs to be done 

to determine how cyanotoxins occur over time. This monitoring should 

also be done over a wide geographical area to determine how cyanotoxins 

are distributed spatially and to establish baseline information for assessing 

how blooms and cyanotoxin distribution are changing over time. This research would clarify how commonly blooms resulting in high concentrations of cyanotoxins occur, and how this is related to geographical location. It is well known that not all cyanotoxins have been described, so the 

distribution of known cyanotoxins may be greater presently understood. 

Thus, studies are also needed to identify new cyanotoxins. 

Analytical Needs 

For continual monitoring and development of research tools, there is a 

long–term need for a stable supply of toxic organisms and toxins. Toxic 

strains of many species commonly have lost their ability to make toxins 

over time in the highly artificial conditions represented by laboratory cultures. To avoid the loss of these sources of toxins, culture collections are 

needed which can supply a continuing source of toxin–producing strains of 

cyanobacteria recently isolated from natural habitats. Similarly, the development of analytical methods and other studies have been hampered by 

lack of availability of analytical chemistry standards for cyanotoxins. Information on concentration or purity of available standards is unavailable

Monitoring Needs 

For long–term priorities, the same types of surveys are needed that were 

described for short–term needs. These surveys would include sampling at 

locations with typical levels of cyanobacteria as well as targeted surveys 

that sample blooms in progress. To respond to the appearance of cyanobacterial toxins in a manner that will minimize public health risk, rapid 

analyses are needed which will permit a response before drinking water 

consumers or recreational water users are exposed to the toxins. Rapid assays or screening methods are needed for this purpose. Data on long–term 

occurrence of cyanotoxins and cyanobacteria that produce the toxins are 

needed to assess how commonly cyanotoxins occur, at what levels, and 

whether there are any long–term changes in their occurrence. 

or ambiguous. Manufacturers need to produce larger supplies of at least the

more common toxins, and to certify their purity. These toxins should be

made commercially available. 

A. Fristachi and J.L. Sinclair
Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 89 

Summary 

Distribution of CHABs across the US 

• Freshwater blooms are ubiquitous across the US and Canada. 

• Most cyanobacterial blooms are in freshwater, but some are found in 

estuarine or marine waters. 

• More detections of cyanotoxins have been reported recently, however, 

increased awareness had led to more monitoring programs. 

• Blooms of cyanobacteria tend to be greater and last longer in warmer 

climates. 

• Detections in ambient waters have been observed to vary from no

rmopsin. Detec-

• Few data are available on temporal changes in cyanotoxin occurrence. 

Cyanotoxin production 

• Determination of taxonomic groups which produce toxins has been 

hampered by uncertainty in the taxonomic definitions for cyanobacteria. 

• Table 1 lists 22 genera and 42 species of cyanobacteria associated with 

toxin formation. 

• Table 2 lists taste and odor–producing species of cyanobacteria. 

detection to 31,470 μg/L for microcystin, no detection to 156 μg/L for

anatoxin–a, and no detection to 202 μg/L for cylindrospe

tions occurred in treated water but concentrations were lower. 

• Table 3 lists the commonly produced types of cyanotoxins in freshwater. 

• Microcystin has been reported to be produced by Microcystis,

Anabaena, Oscillatoria (Planktothrix), Nostoc, Hapalosiphon and Anabaenopsis

• Cylindrospermopsin is produced by Cylindrospermopsis raciborskii,

Aphanizomenon ovalisporum, and Uzmekia natans. 

• Anatoxin–a is produced by Anabaena flos–aquae, A. planktonica, Oscillatoria species, and Cylindrosperum. Homoanatoxin–a, was isolated 

from Phormidium Formosa

. 

. 
• Anatoxin–a(s) was reported from A. flos–aquae strain NRC 525–17 and 

more recently by A. lemmermannii

• Saxitoxin and related toxins are made by Aphanizomenon flos–aquae, 

Anabaena circinalis, Lyngbya wollei and a Brazilian isolate of Cylindrospermopsis raciborskii

• BMAA is produced by Nostoc species and many others. 

• Lyngbyatoxins aplysiatoxin and debromoaplysiatoxin are made by 

Lyngbya, Oscillatoriaceae such as Schizothrix calcicola and Oscillatoria

nigroviridis

• Cyanobacteria also produce other bioactive compounds. 

Impacts on waterbody health and ecosystem viability 

• The factors that lead to bloom formation and toxin production are not 

well understood. Light, temperature, hydrological and chemical factors 

may be involved. 

• In freshwater, blooms in Metropolitan Water District’s reservoirs have 

led to taste and odor problems. A sewage spill in North Carolina led to 

a Lyngbya bloom. 

• In estuarine habitats including the upper Chesapeake Bay, cyanobacterial blooms occurred with an invasion of water milfoil. Cyanobacterial blooms with fish kills have occurred in brackish Lake Ponchartrain, Louisana from freshwater or nutrient influxes. 

• Ecological effects have occurred as a result of cyanobacterial blooms 

that are caused by effects other than toxin production. 

Data Needs 

• A consensus is needed for species level taxonomy for cyanobacteria. 

• Existing information needs to be compiled into an accessible form. 

• New surveys should be conducted (including UCMR monitoring of 

drinking water), especially for newly emerging toxins in raw water and 

drinking water. 

• A national monitoring program is needed for recreational water. 

. 

. 

. 

90 A. Fristachi and J.L. Sinclair
Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 91 

• Analytical methods are needed including screening methods, 

instrumental methods, and online and remote detection. Sample 

preparation methods and analytical chemistry standards are needed to 

support analytical methods. 

• A better understanding is needed of what factors lead to bloom 

formation and cyanotoxin production. 

• The relation between toxin retention and release for different toxins 

needs to be clarified. 

• Accumulation of cyanotoxins in the tissues of fish and shellfish needs 

study. 

• A website is needed for reporting of cyanotoxin occurrence information. 
92

Glossary 

Akinete – thick–walled, often enlarged cell that can survive adverse conditions 

and form a new filament; often refractive under light microscopy because it is 

filled with food reserve (cyanophycean starch); also often orangish in color from 

abundant, protective carotenoid pigments. This specialized cell is found in some 

members of the Order Nostocales. 

Anaerobic – Without oxygen. 

Anoxic – Referring to habitats with little or no oxygen, such as the bottom waters 

of many eutrophic lakes in summer 

Avian vacuolar myelinopathy [AVM] – a recently discovered neurological disease affecting water birds and their predators, primarily American coots and bald 

eagles, in the southern US. AVM causes characteristic lesions in the myelin of the 

brain and spinal cord. 

Benthic – Living in or on the bottom of a body of water, or growing attached to 

various substrata including other organisms (e.g. the noxious aquatic weed, hydrilla), but not free–floating in the water column. Note: Many benthic cyanobacteria can be moved into the plankton by wind/waves or other disturbance, and can 

thrive in the water column. 

Brackish – Somewhat salty, as in brackish (estuarine) water.

Buoyant – Floats easily, and is less dense than water.

Chlorophyll a – The “universal plant pigment”, found in all organisms that undergo plant–like photosynthesis with production of oxygen. The concentration of 

this pigment is often used as an indicator or surrogate measure for algal biomass 

or production. 

Cyanobacteria – Formerly (and sometimes still) called blue–green algae, cyanophytes or mixophytes (means “slime plants”). In present–day taxonomy, considered a type of bacteria (“blue bacteria”) because of their primitive cell structure 

and other features, although they have the “universal plant pigment” that is directly involved in “higher plant” photosynthesis, chlorophyll a.

Estuary – A semi–enclosed body of water where saltwater mixes with freshwater. 

A. Fristachi and J.L. Sinclair
Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 93 

Eutrophic – Referring to aquatic freshwater and/or estuarine/coastal ecosystems 

that are nutrient–enriched and highly productive.

Filamentous – Group of cells aligned in a row; very thin, threadlike. 

Freshwater – Aquatic ecosystem with salinity lower than 0.1 ppt (see below). 

Genus (plural: genera) – A taxonomic group below family and above species 

Habitats – The places where plants and animals live. 

Harmful algal bloom – A proliferation of microscopic or macroscopic algae that 

are capable of causing disease or death of humans or beneficial aquatic life 

through production of toxins, or that adversely affect aquatic ecosystems through 

other mechanisms (e.g. by depleting oxygen needed to sustain fish, or by reducing 

light that is essential for growth of beneficial submersed plants). 

Heterocyte (formerly heterocyst) – thick–walled cell, usually pale in color compared to the other cells, used for nitrogen fixation in some cyanobacteria. This 

specialized cell is found in some members of the Order Nostocales. 

Heterotroph – An organism that depends on consumption of other organisms and 

organic material for energy. 

Hypersaline – referring to water with salinity higher than average seawater salinity.

Indicator species – A species whose status provides information on the overall 

health of the ecosystem and of other species in that ecosystem. Indicator species 

reflect the quality and changes in environmental conditions as well as aspects of 

community composition. 

Macrophyte – Usually referring to a rooted submersed aquatic plant.

Mesohaline – Moderately salty water (salinity range 5–18 ppt). 

Mixotroph – An organism that uses both photosynthesis and particulate or dissolved organic substances made by other organisms for its energy. Many cyanobacteria are mixotrophs. 

Oligohaline – Low salinity (0.5–5 ppt).
94

Phytoplankton– Microscopic algae that live and reproduce suspended in the water column of freshwater, estuarine, and marine ecosystems. Phytoplankton form 

the base of the food web in many aquatic ecosystems. 

Picoplankton – Very small phytoplankton in aquatic ecosystems, including 

cyanobacteria (diameter 0.2 – 2 μm). 

Polyhaline – Referring to waters that are variable in salinity, often highly brackish 

water with a salinity of 18–30 ppt. 

Ppt – Parts per thousand, a measure of salinity. For example, the salinity of the 

open ocean is generally about 35 ppt; freshwaters are < 0.1 ppt. 

Reservoir (impoundment) – an artificial (man–made) lake, formed by damming a 

river. 

Specialized cell – akinete, heterocyte (see above). 

Strain – A population within a given species of cyanobacteria or microscopic algae. 

Terrestrial – Living or growing on land or in the soil.

Tidal freshwater – Freshwater (0–0.5 ppt) that is tidally influenced. 

Toxigenic – potentially toxic; referring to a species of cyanobacteria that is known 

to have some toxic strains. (Note: toxigenic algae have both nontoxic and toxic 

strains.) 

A. Fristachi and J.L. Sinclair
Chapter 3: Cyanobacterial Harmful Algal Blooms Workgroup Report 95 

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