Harmful Algal Blooms- Cover Page

Harmful Algal Blooms (HABs) are of national concern because they adversely

affect not only the health of people and marine organisms, but also the "health"

of local and regional economies. Health effects range from cell damage to

organism mortality through such mechanisms as toxin production and localized

conditions of low oxygen. For the past several decades, harmful algal blooms

have caused more than $1 billion in losses in the United States, with resources

diverted to monitoring programs, closures of shellfish beds and coastal

fisheries, severe reductions in local and regional tourism and associated service

industries, public illness, and medical treatments and advisories. Harmful algal

blooms occur in almost every U.S. coastal state; examples include

toxin-producing dinoflagellates in New England, the mid-Atlantic, the Gulf of

Mexico, the entire West Coast including Alaska, and tropical and subtropical

states and possessions; toxic diatoms in the Gulf and along the West Coast; and

toxin-producing flagellates and gill-clogging diatoms in the Pacific Northwest.

Research, monitoring, and education efforts focus on ways to mitigate and

prevent future outbreaks of harmful algal blooms.

To cite this material. This material has been produced by the Government of

the United States of America and holds no copyright.

The following reference format is suggested:

Bushaw-Newton, K.L. and Sellner, K.G. 1999 (on-line). Harmful Algal

Blooms. In: NOAA's State of the Coast Report. Silver Spring, MD: National

Oceanic and Atmospheric Administration. http://state-of-coast.noaa.gov/

bulletins/html/hab_14/hab.html

For questions on figures or photographs used in this essay, contact Kevin

Sellner, Center for Sponsored Coastal Ocean Research, National Oceanic and

Atmospheric Administration, Silver Spring, MD 20910
Harmful Algal Blooms - Introduction

Photo 1. A bloom of Noctiluca colors the

seawater in a phenomenon commonly known as

"red tide." At about two millimeters in

Throughout the world's coastal oceans, observations of harmful algal

blooms (HABs) are being reported with increasing frequency. Often, these

events are accompanied by severe impacts to coastal resources, local

economies, and public health. Harmful algal blooms -- accumulations of

microscopic species of algae or the larger, multicellular species -- appear to

be more devastating than ever before, and may be increasing over time.

Some species recur in the same geographic regions each year, while others

are episodic, leading to the unexpected deaths of local fish, shellfish,

mammals, and birds. While the impacts appear to be both obvious and on

the rise, only about 50 of the thousands of known algal species actually

produce toxins. Some of these toxins have direct and deleterious effects on

local plants and animals; others have indirect affects on organisms by

changing local environmental conditions.

In general, most harmful algal blooms are caused by plants

(photosynthetic organisms) that form the "base" of the food chain. These

include both microscopic species of algae, referred to scientifically as

phytoplankton and the microphytobenthos, as well as the larger

macroalgae. Other HABs are caused by accumulations of

nonchlorophyll-containing cells (heterotrophs) that are similar in form to

microscopic algae. A bloom occurs when an alga or heterotroph rapidly

increases in numbers to the extent that it dominates the local planktonic or

benthic community. Such high abundance can result from explosive

growth, caused, for example, by a metabolic response to a particular

stimulus (e.g., nutrients or some environmental condition like a change in

water temperature), or from the physical concentration of a species in a

certain area due to local patterns in water circulation. The similarity of

these alga and heterotrophs often makes it difficult to identify the precise

cause of a harmful algal bloom, and to predict its impact on the affected

ecosystem.

It is a challenge to define a harmful algal bloom and to characterize the

species that causes it. All HABs were once referred to as "red tides"

because of the color imparted by algae suspended in the water, but the

description has since become a misnomer because not all HABs are red

(some may be brown, yellow, or green), and some may not discolor the

water at all. Color is imparted through cellular concentrations of pigments

like chlorophyll or lower abundance pigments. Examples of HABs that are

readily associated with water discoloration are blooms of many species of

cyanobacteria, generally visible as floating green scums or colonies in

coastal environments; two "brown tide" species (Aureococcus and

Aureoumbra ) that turn coastal lagoons dark chocolate brown; the

dinoflagellates Alexandrium spp., Gymnodinium breve, and

Noctiluca spp., that cause red water; and blooms of macroalgae.

However, no color is visible in other harmful species, such as the

chlorophyll-free dinoflagellate Pfiesteria piscicida , several

Dinophysis species, and benthic microalgae (e.g., Gambierdiscus ) that

grow on the surfaces of larger macoroalgae in tropical waters. Both

Pfiesteria and Dinophysis also impart toxicity at very low densities,

generally less than 1,000 cells per liter (Burkholder and Glasgow 1997,

Smayda 1997). In comparison, macroalgae are considered harmful due to

dense overgrowth that can occur in localized areas, such as coral reefs of

the tropics or coastal embayments receiving excessive nutrient loading

(LaPointe 1997, Valiella et al. 1997). Accumulations can be so high as to

cover the bottom of a region, excluding other biota as well as creating an

environment in which high oxygen consumption and the associated anoxic

conditions accompany decomposition of the accumulated or displaced

biomass.

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Detrimental Effects of Harmful Algal Blooms
Harmful Algal Blooms - Introduction

diameter, Noctiluca is the largest of the

dinoflagellates. The detrimental effects of a harmful algal bloom can range from cell and

tissue damage to organism mortality, and can be caused by a number of

mechanisms, including toxin production, predation, particle irritation,

induced starvation, and localized anoxic conditions. As a result, a bloom

may affect many living organisms of the coastal ecosystem, from

zooplankton to fish larvae to people.

Toxins. As noted above, only a few HAB species actually produce

toxins that are poisonous to people and marine animals. The most well

known HAB toxins are generically referred to as ciguatera fish poisoning

(CFP), neurotoxic shellfish poisoning NSP), paralytic shellfish poisoning

(PSP), diarrheic shellfish poisoning (DSP), and amnesic shellfish

poisoning (ASP). Pfiesteria piscicida also produces two toxic

fractions, dermonecrotic and neurologic toxins that impact fishes and

humans (Bever et al. 1998, Grattan et al. 1998) (Lowitt and Kauffman

1998) (Noga et al. 1996). Cyanobacteria also produce similar toxins that

overlap with several of these general categories, including neurotoxins and

hepatoxins.

Symptoms of exposure to these toxins include gastrointestinal,

neurological, cardiovascular, and hepatological symptoms. The algae that

produce these toxins, and the specific symptoms they cause, are

summarized in Appendix A. The terms "fish" and "shellfish" are

associated with these illnesses because the toxins concentrate in the fish

and shellfish that ingest the harmful algae; people and marine mammals

may be poisoned when they consume the affected seafoods.

Other harmful algal blooms produce toxins with no identifiable effects on

humans but devastating impacts on coastal living resources. For example,

the flagellate Heterosigma akashiwo is thought to produce an

ichthyotoxin that kills fish (Taylor and Horner 1994), resulting in

significant threats to penned fish in mariculture operations.

Predation. Predation is another way that several HAB species can impact

coastal biota. Predation occurs when one organism captures or feeds on

another organism. One example of a predatory HAB is Pfiesteria

piscicida. There is accumulating evidence that this dinoflagellate

produces several toxic "fractions" that assist in prey capture. Two of these

toxic fractions are produced after the P. piscicida is exposed to fish

secretions. The first fraction has neurotoxin-like properties that affect the

fish's neurological system. The second has skin-killing (dermonecrotic)

characteristics. The neurotoxin-like materials cause lethargy in the fish,

and, when present in sufficient quantities, death. The dermonecrotic

compounds apparently cause sloughing of the external skin layers, leading

to lesions and perhaps secondary infections from fungi and other

pathogens in the surrounding water. Fish kills coincident with Pfiesteria

are likely to be a result of direct exposure to toxic compounds produced by

the dinoflagellate, secondary infections associated with lesions, or a

combination of both (Noga et al. 1996, USEPA 1998). Fish mortality is

then followed by dinoflagellate ingestion of fish tissue.
Harmful Algal Blooms - Introduction

Photo 3. This algae species of the genus

Chaetoceros kills with its spiny, serrated

filaments, which clog the gills of fish that feed

on them.

Photo 2. These lesions, believed to be caused by toxins produced by

the dinoflagellate Pfiesteria piscicida , make fish such as these

menhaden vulnerable to secondary infections.

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Particle Irritation. Several HAB species, specifically two

spine-forming diatoms (Chaetoceros cavicornis and C. convolutus ),

also cause significant problems for coastal fish that are commonly

produced in mariculture operations. The deaths of fish and crustaceans

occur because large numbers of these spiny phytoplankton become trapped

in the animals' gills, resulting in mucus accumulation and respiratory

failure, hemorrhaging, and bacterial infection (Rensel 1993b).

Induced Starvation. HABs can cause organisms to starve through

nutritional and size mismatch (Smayda 1997). Organisms that ingest

HABs are often unable to ingest enough high-quality food to survive. The

brown tide organism Aureococcus reduced ingestion of nutritious algae

in bay scallop larvae by interfering in the scallops' ciliated esophagus

(Gallager et al. 1989). In adult suspension-feeding bivalves, the alga

inhibits the activity of lateral cilia in the gill, the main organ of particle

capture (Gainey and Shumway 1991), ultimately reducing growth (Bricelj

et al. 1999). Other HAB species may be too small, too big, taste badly, or,

as in the ingestion of Prorocentrum minimum by oyster larvae or spat,

alter the absorption capabilities of the organism's digestive system

(Wikfors et al. 1995). Bloom densities of P. minimum actually kill

juvenile oysters (Luckenbach et al. 1993) and bay scallops, possibly by

interfering in the shellfishes' ability to produce digestive enzymes or by

causing atrophy of the digestive tissue (Wikfors and Smolowitz 1993,

1995).

Localized Anoxic Conditions. Excessive accumulations of algae,

whether as a micro- or macroalgal bloom, are often followed by high

decomposition rates of the accumulated material. The decomposition is

accompanied by oxygen consumption, stripping local waters of available

oxygen and leading to hypoxia (low oxygen) or anoxia (no oxygen).

Without oxygen, most marine biota cannot survive, resulting in mass

mortalities of fish and shellfish. Crustacean deaths occur because large

numbers of algal cells become trapped in the creatures' gills, causing

respiratory failure, hemorrhaging, or bacterial infection (Smayda 1997).

Species of the diatom genus Chaetoceros, for example, become lodged

in the gills, where their spiny filaments destroy the hosts' tissue.

Historical Context

Harmful algal blooms are not new phenomena, with written references

dating back to Biblical times. Dinoflagellates have been found in the fossil

record for millions of years, and cyanobacteria were the first

photosynthetic life forms on Earth. According to Dr. Don Anderson, who

researches algal species at the Woods Hole Oceanographic Institute in

Massachusetts, "There are more toxic algal species, more algal toxins,

more fisheries resources affected, more food-web disruption, and more

economic losses from harmful algal blooms than ever before" (Anderson

et al. 1993) (Figure 1). The interest in HABs stems, in large part, from

increased public awareness of the negative impacts to marine resources,

e.g., strandings and deaths of marine mammals, birds, and sea turtles;

increased monitoring efforts and improved methods of detection; and the

establishment of linkages between initial exposure and subsequent

symptoms displayed by organisms exposed to a HAB species.

Understanding the ecology and oceanography of these species, and how

they affect other organisms, including people, continues to be a challenge

for researchers. In 1995, a federal interagency program known as
Harmful Algal Blooms - Introduction

, g yp g

ECOHAB (Ecology and Oceanography of HABs) was initiated to support

HAB research in the United States (Anderson 1995).

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Harmful Algal Blooms - National Picture

Harmful algal blooms are having significant impacts on coastal areas of the

United States and the rest of the world, affecting the health of both humans

and marine organisms and the vitality of local and regional economies.

Their presence and persistence represent a significant and expanding threat

to human health and marine resources across the nation (Anderson et al.

1993). The numbers and diversity of reported HAB incidents have

increased during the past 25 years (Figure 2) to include almost every U.S.

coastal state. Understanding the causes of these phenomena, and mitigating

and preventing their consequences, are national concerns.

Most harmful algal blooms result from the transport of offshore

populations to inshore regions, i.e., physical relocation independent of

human activities. Examples of the importance of water circulation and

bloom events abound. The largest blooms observed, those of

Trichodesmium in the open ocean, occur far from any coastal inputs

(Sellner 1992, 1997). In the Baltic Sea, summer blooms of Nodularia

and Aphanizomenon have occurred since late in the last century, likely

due to the mixing of regenerated nutrients from depths below the seasonal

and permanent pycnoclines during meteorological events, or from mixing

events induced by North Sea inflows (Sellner 1992, 1997, Kononen and

Nommann 1992). The organisms responsible for diarrheic shellfish

poisoning, Dinophysis spp., are often swept into coastal rias and river

mouths through wind-induced upwelling (Pazos et al. 1995). Blooms of

Alexandrium tamarense, responsible for paralytic shellfish poisoning

(PSP) in people, are often initiated when cells are transported into the Gulf

of Maine from the eastern provinces of Canada, and then further south into

Massachusetts Bay (Anderson 1997). Blooms of Gymnodinium breve,

responsible for neurotoxic shellfish poisoning, occur when cells from

small, offshore populations in the open Gulf of Mexico are advected onto

the west Florida shelf and into the coastal waters of other states bordering

the Gulf of Mexico, and even into North Carolina estuaries (Tester and

Steidinger 1997, Dortch et al. 1998). The dinoflagellate Gyrodinium

aureolum, producing compounds that narcotize fish gills and congest

bronchial blood vessels, is transported into Norwegian fjords from

offshore populations (Lindahl 1986, Dahl and Tangen 1990). This

consistent delivery of many HABs from offshore to inshore regions

produces an aperiodic infusion of potentially dangerous HABs into most

areas of the world's coastal oceans, even those that are independent of

human actions on shore or coastal watershed activities. As a result,

attempts to prevent HAB events are somewhat impractical, because people

cannot control general oceanic ciruclation or even localized coastal currents.

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Photo 4. The "Gulf Stream" (dark blue) from the Gulf of Mexico to

the Atlantic Ocean can transport large populations of the

dinoflagellate Gymnodinium breve to near-coastal waters such as

here off the outer banks of North Carolina.
Harmful Algal Blooms - National Picture

The Consequences of Harmful Algal Blooms

The expansion of harmful algal blooms during the past 20 years is

responsible for losses approximating $100 million per year nationwide

(Turgeon et al. 1998). After an outbreak, not only are health issues a major

concern, but many industries also are affected (Figure 3). Closures of

shellfish beds, lost production in fisheries (both aquaculture and wild),

severe reductions in local/regional tourism and associated service

industries, public illness, and medical treatments and advisories result in

the loss of millions of dollars per outbreak. For fisheries-related

businesses, insurance rates increase, unemployment and bankruptcies rise,

and retail sales typically decline for all seafood species; at the same time,

public resources are diverted to monitoring programs.

Photo 5. Outbreaks of harmful algal blooms can kill thousands of

fish and cost millions of dollars in lost fisheries revenues.

The direct and indirect losses attributed to HAB events are staggering to the

local areas in which they occur. A single outbreak of paralytic shellfish

poisoning in the Northeast was estimated to cost $6 million (Shumway

1988). The 4- to 6-month red tide in North Carolina during 1987-1988 was

estimated to have cost the community $25 million (Tester and Fowler

1990). The 1991 outbreak of domoic acid/amnesic shellfish poisoning in

Washington had a negative impact on the entire community, from the

tourism industry to unaffected fisheries (oysters), with losses estimated

between $15 and $20 million. In North Carolina, recent outbreaks (1995

and 1996) of Pfiesteria piscicida and Pfiesteria -like dinoflagellates

have resulted in the deaths of millions of fish, including the commercial

menhaden, due to secondary infections and/or toxins (Burkholder and

Glasgow 1997). In addition, a recent outbreak of Pfiesteria or

Pfiesteria -like organisms in the Chesapeake Bay resulted in a public

outcry, an estimated $43 million loss for the seafood industry, and several

reported incidents of illness in people (Sieling and Lipton 1998).

Even a nontoxic harmful algal bloom can have devastating effects on a

natural community. In South Florida, blooms of macroalgae are

overwhelming sections of coral reef ecosystems and seagrass beds

(LaPointe 1997). Besides being one of the most productive and diverse

marine ecosystems, coral reefs are a vital component of the South Florida

economy, attracting thousands of visitors each year. Seagrass beds are

important nursery habitat for pink shrimp, spiny lobster, and finfish.

Continued overgrowth of algae could eliminate these refuges of

biodiversity and lead to severe economic losses for the recreation and

tourism industries. In Long Island, brown tide severely impacted the bay

scallop industry (Nuzzi and Waters 1989) with the collapse and permanent

loss of the $2 million per year industry. In Washington, Heterosigma

akashiwo blooms have caused losses of $4 to $5 million per year to

harvesters of wild and penned fish (Horner et al. 1997). Finally, in the

same region, economic losses due to blooms of Chaetoceros, which

mainly affect penned fisheries, are estimated to result in losses of about

$500,000 per episode (Rensel 1993a).

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Harmful Algal Blooms - National Picture

Photo 7. Improved methods of detection have

helped scientists determine that harmful algal

blooms occur over a greater area in some parts

of the country than was previously observed.

Photo 6. Blooms of macroalgae, like this outbreak of Codium

isthmocladum that washed ashore in Florida, choke the seagrass

beds, cause oxygen depletion in the water, and result in losses to the

recreation and tourism industries.

Possible Causes of the Increase in Harmful Algal

Blooms

The frequency, duration, and intensity of algal blooms are related to a

number of biological, chemical, and physical factors, although, many of

these complex relationships have not yet been identified. Four possible

reasons have been advanced for the increased frequency and expanding

geographic occurrence of HABs. First are improved methods of detection

and greater monitoring efforts. These increase the probability that a HAB

species will be recorded. Second is the introduction of exotic species via

ballast water exchange or aquaculture practices (Hallegraeff 1993). A third

possibility is that blooms result when grazers fail to control the algal

species' growth (Smayda 1990). Fourth, blooms may result from climate

changes, as well as human activities, such as increased pollution and

nutrient inputs, habitat degradation including dredging, resource

harvesting, and the regulation of water flows. All of these reasons are

possible explanations for increasing HABs, and one or any combination of

them may apply to a particular species.

Improved Methods of Detection and Greater Monitoring

Efforts. Outbreaks of paralytic shellfish poisoning caused by species of

Alexandrium have occurred in the Northeast and Pacific Northwest for

hundreds of years. Scientists do not believe that their frequency has

increased, but rather, that the extent of these outbreaks occurs over a

greater area than previously recorded (Boesch et al. 1996). Similarly, there

is no evidence of an increased frequency of G. breve blooms in Florida,

but the blooms seem to be more extensive and last longer (Boesch et al.

1996). On the other hand, HABs are being recorded today in coastal areas

that had not experienced the problem two decades ago. For instance, North

Carolina, Louisiana, Mississippi, and Alabama have all recently

experienced G. breve blooms (Tester et al. 1991, Dortch et al. 1998). In

addition, brown tides, caused by Aureococcus anophagefferens and

Aureoumbra lagunensis, have become recurrent problems along the coast

of Long Island and in the Laguna Madre of Texas within the last 15 years

(Cosper et al. 1987, Buskey and Stockwell 1993). Finally, outbreaks of

amnesic shellfish poisoning have only been known to science since 1987

(Bates, 1998). Recently, domoic acid-induced mortalities in sea lions and

possibly birds and sea otters have plagued Southern California waters in

the summer of 1998 and late spring of 1999 otters (Scholin et al. in

review).

Introduction of Exotic Species via Ballast Water Exchange and

Aquaculture. Currently, there is some evidence that ballast water may

have introduced harmful algal blooms into Australian waters (Hallegraeff

1993), although recent information suggests that more local populations

from Australian waters may be the actual source material for the blooms

(Bolch et al. 1998). Ballast delivery has not been definitely shown in the

United States (Boesch et al. 1996). Although circumstantial evidence

suggests that HABs may have been introduced in the United States, current

methods cannot determine when the dispersal occurred (i.e., over a few

years versus millions of years) (Scholin and Anderson 1993). Genetically

similar populations of several HAB species exist both in the United States

and in other parts of the world, indicating that a dispersal has occurred, but

the time and mode remain to be determined (Scholin and Anderson 1993).

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Failure of Control by Grazers. Grazers' ability to regulate an algae

population depends on timing as well as biological, chemical, and physical

factors. Interactions between grazers (zooplankton in the case of

phytoplankton, and larger crustaceans and mammals in the case of

macroalgae) and HAB species appear to be specific. Apparently, toxins do

not affect all consumers. Some zooplankton are able to eat the toxic algae
Harmful Algal Blooms - National Picture

without any effects, while other grazing zooplankton experience decreases

in motility or fecundity, or die (Turner and Tester 1997). For example,

Brachionus plicatilis, a rotifer, can feed on Pfiesteria piscicida

without any deleterious effects (Burkholder and Glasgow 1995), but

exhibits reduced feeding when Heterosigma carterae is ingested

(Chotiyaputta and Hirayama 1978). In the case of another HAB

(Aureococcus anophageefferens ), it has been proposed that reduced

grazing by protozoa resulted in the 1985 brown tide in Narragansett Bay

(Smayda and Villareal 1989). The suite of results indicate that grazing

losses are HAB-specific, leading to poor elucidation of the importance of

grazing control in most areas (Turner and Tester 1997).

Human Activities. Strong relationships appear to exist between several

algal groups and nutrient enrichment in certain localities. These few

observations have resulted, perhaps erroneously, in a refrain that coastal

eutrophication is responsible for global increases in HABs. The two algal

groups that appear to bloom in response to increasing nutrient loadings

include cyanobacteria (formerly known as blue-green algae) (Anderson et

al. 1995) and macroalgae (Valiela et al. 1997). Nutrients may also be

responsible for the proliferation of specific species. Higher densities of the

nontoxic life stages of Pfiesteria piscicida have been reported in

nutrient-rich waters resulting from hog farm overflows and sewage

discharge, as well as from growth stimulation in laboratory cultures

enriched with nitrogen or phosphorus (Burkholder and Glasgow 1997). In

the North Sea, Phaeocystis may be increasing because both nitrogen and

phosphorus inputs are on the rise, while silicon inputs remain low, the

latter limiting the duration of a typical diatom bloom, leaving the excess

nitrogen and phosphorus available for the Phaeocystis population

(Lancelot et al. 1987). Localized nutrient enrichment resulting from human

activities has resulted in serious HAB problems for two locales in Asia, the

Seto Inland Sea in Japan (Okaichi 1989) and Hong Kong Harbor (Lam and

Ho 1989), now considered the "classic examples" of human-induced HAB

proliferation. Finally, river discharge and enhanced nutrient enrichment

availability have been suggested as potential reasons for both past and

recent blooms of toxic Pseudo-nitzschia, leading to amnesic shellfish

poisoning and fatalities in mammals, including people (Smith et al. 1990;

Scholin et al. in review).

Prevention, Control, and Mitigation 

Because of the large impacts of coastal HABs, the control and prevention

of problem species are of major interest to many groups. Control,

mitigation, and prevention, however, are not straightforward matters, due

to the complexities and current knowledge of bloom dynamics and the

secondary effects that arise from intervention procedures. Federal and state

agencies are working closely with local governments, academic

institutions, and nonprofit groups to mitigate the effects of HABs and to

develop prevention technologies for the future. Current research focuses on

(1) identifying toxins, (2) developing routine tests for field monitoring of

the nutritional and life-cycle characteristics of HAB species, (3) developing

rapid and inexpensive tests for detecting the presence of HABs in coastal

waters, (4) evaluation of specific flocculation procedures to strip HABs

from coastal waters, and (5) isolation and characterization of natural viral

and bacterial populations that might be used in biological control of HABs.

Water-quality monitoring programs are accumulating baseline data about

the status of water quality preceding and coincident with harmful algal

blooms. These data will prove useful in the future development of HAB

forecasting capabilities and predictive models. Information is widely

available to the public from federal and state agencies, Web sites, and the

National Office of Marine Toxins and Harmful Algae at Woods Hole

Oceanographic Institute.

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Harmful Algal Blooms - Regional Contrasts

Photo 8. Members of the genus Alexandrium

Harmful algal blooms occur in all coastal regions of the United States.

Figures 4-7 illustrate the general distribution of HABs that result in known

diseases. Although many of the same algae species appear in different

regions, bloom conditions are not necessarily similar, nor are they fully

understood. While the same species cause the same types of HAB

problems in different regions, they may affect different organisms. Table 1,

and the region-by-region discussion that follows, demonstrate the diversity

of HABs in U.S. coastal areas.

Northeast

The chief HAB in the Northeast, Alexandrium tamarense, is responsible

for annual outbreaks of paralytic shellfish poisoning. Alexandrium cells

are entrained in two coastal currents in the region. One of these currents

flows to the southwest, coinciding with river outflows in late May and

early June, and creating an annual north-to-south toxicity pattern. In

addition, dynamics of the currents and river-generated plumes are highly

influenced by freshwater inflow, wind, and depth, which strongly govern

the distribution of toxic cells and, therefore, their impacts.

Northeast and Mid-Atlantic

From the Northeast through the Mid-Atlantic region, specifically in

lagoonal systems of eastern Long Island, New Jersey, Delaware, and

Maryland, brown tide is a recurring HAB problem. The first recorded

outbreak was in 1985 in Long Island. Several have occurred since then, the

most recent along Maryland's Eastern shore in 1999. Impacts include the

loss of submerged aquatic vegetation and the collapse of several

shellfisheries, such as the bay scallops of eastern Long Island. The

outbreaks occur from late spring to early summer and last from one to four

months.

Another HAB group common to the Mid-Atlantic region is Pfiesteria

piscicida and similar-looking cells known as Pfiesteria -complex

organisms. In many environments, P. piscicida and P. -complex

organisms have co-occurred with high numbers of fish with epidermal

lesions, which, over time, may cause death due to secondary infections.

Further, some evidence suggests that the fish secretions that accumulate in

dense fish aggregations induce toxicity in some life stages of P. piscicida,

resulting in the production of two toxic "fractions," one that is neurotoxic

to the surrounding fish, and one that is dermonecrotic (i.e., causes the skin

to slough and die). This combination of toxins from P. piscicida and the

secondary infections resulting from pathogenic bacteria, fungi, and

protozoa is probably responsible for the recent fish kills in several systems

of Maryland's Eastern Shore and in coastal North Carolina.

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The mechanisms responsible for the expression of Pfiesteria -related

health problems in fish are not yet understood, although increasing

information points to the importance of inorganic and organic nutrient

enrichment as favorable growth conditions for the troublesome organism.

Burkholder and Glasgow (1997) documented increasing numbers of

nontoxic P. piscicida cells in hog-pond effluents and waters immediately

downstream of sewage treatment discharge, as well as elevated cell

numbers in cultures enriched with inorganic and organic nitrogen and

phosphorus. Magnien et al. (1998) have suggested that the coincidence of

several factors could explain the Pfiesteria -associated fish kills along
Harmful Algal Blooms - Regional Contrasts

are responsible for outbreaks of paralytic shellfish

poisoning in the Northeast and the Northwest.

Maryland's Eastern Shore in the late summer of 1997. These include

resident low levels of P. piscicida, long residence times of nutrient-rich

waters in shallow, chlorophyll-rich brackish waters of poorly flushed river

mouths, and high densities of coastal menhaden. If these same factors were

to coincide in other systems, they might be explored as potentially

responsible agents for recurrent fish kills and other health problems in the

Mid- and South Atlantic regions.

Photo 9. The amoeboid stage of Pfiesteria piscicida shown here

has been magnified several hundred times.

Southeast

Southeastern states experience the same problems with Pfiesteria blooms

as those in the Mid-Atlantic. In 1995 and 1996, the deaths of thousands,

and in a single incident, millions, of fish from the coastal waters of North

Carolina were attributed to Pfiesteria or Pfiesteria -like species

(Burkholder and Glasgow 1997). Another HAB that has had an impact on

southeastern states is Gymnodinium breve, which produces the toxin

responsible for neurotoxic shellfish poisoning (NSP). Blooms are usually

seasonal, starting in the late summer to early fall and lasting about three to

four months. They appear to derive from offshore Gulf of Mexico

populations, to increase over the west Florida shelf, and may later be

transported to the South Atlantic Bight via the Loop Current and the Gulf

Stream (Tester and Steidinger 1997).

Gulf of Mexico

In the Gulf of Mexico, the major HAB problems are brown tides and

outbreaks of NSP caused by G. breve. In the Laguna Madre system of

Texas, a dense bloom of the brown tide species Aureoumbra lagunensis

persisted for more than seven years after its appearance in 1990 (Buskey et

al. 1997). The bloom may have resulted from an unusual weather event

during which subfreezing temperatures caused a massive fish kill, which,

in turn, provided a pulse of nutrients to the hypersaline lagoonal waters.

Additionally, resident grazer populations (e.g., microzooplankton, benthic

organisms) were low prior to the bloom, suggesting that grazing losses

may have allowed the initial development of A. lagunensis. The only

demonstrable impact from the 7-year event was a loss of submerged aquatic

vegetation in the deeper depths of the lagoon, due to light attenuation

(Dunton 1994, Onuf 1996); fish densities remained the same.

The term "red tide" is now part of the common language and is associated

with G. breve blooms that have occurred along Florida's western shelf

since the 1950s. These blooms have been recorded since the Spanish

explorations of the late 16th century, and have been reported in 23 of the

last 24 years. The organism produces brevetoxin, which is the cause of

neurotoxic shellfish poisoning in people and other mammals. This toxin

causes huge problems nearly every year, including fish and mammal

mortalities and mass closures of shellfish beds from Florida through Texas.

A bloom of G. breve just south of Tampa Bay killed more than 150

manatees in 1996, and another killed more than 21 million fish along the

Texas coast in 1997-1998. Some single events have been estimated to cost

$20 million in lost revenues. People can become ill after eating affected

shellfish, but more commonly, respiratory distress occurs in compromised

individuals, such as older citizens and asthmatics, who have inhaled the

toxin while in or near the water.

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Pacific
Harmful Algal Blooms - Regional Contrasts

On the Pacific Coast, paralytic shellfish poisoning (PSP), amnesic shellfish

poisoning (ASP), and finfish mortalities from blooms of the Heterosigma

and Chaetoceros species are major HAB problems. Outbreaks of PSP are

recurrent, although the bloom dynamics are not well understood. Off the

coast of California, the first major outbreak of ASP was reported in the

summer of 1991. Since that time, domoic acid has been found in both

autumn and spring plankton communities. In Monterey Bay, blooms of the

domoic acid-producing diatom Pseudo-nitzschia are most common in the

summer and autumn months, whereas in southern California, blooms are

most common in the late spring to early summer. In late May through June

1998, the deaths of more than 50 sea lions, and illnesses in several other

sea lions, birds, and sea otters, were attributed to domoic-acid poisoning

caused by a bloom of the diatom P. australis off the coast of California

near Santa Cruz (Scholin et al. in review). Although domoic acid was not

detected in the tissues of many of the sea lions, it was found in the urine of

several. Furthermore, investigating scientists from state, university, and

federal labs detected high levels of domoic acid in sardines and anchovies,

which are common foods of sea lions (Scholin et al. in review). Lesions of

the hippocampus portion of the brain, characteristic of domoic-acid

exposure in mammals, were also observed in several of the dead animals.

Off the coast of Washington, little is known about bloom dynamics for any

of the HAB species, but parts of the coast have to be closed to bivalve

harvesting on a year-round basis. Mass mortalities of penned fish have

been recorded in fjords of the region, due to the flagellate Heterosigma

and two diatom species of Chaetoceros. The former likely produces an

ichthytoxin, while the spiny diatoms clog the gills of fish, leading to

excessive mucus production and suffocation. In Alaska, recurrent blooms

of the PSP-producing Alexandrium species -- also seen in the Gulf of

Maine -- during nearly every month of the year has eliminated the

development of any shellfishery, and has caused the deaths of several

native people.

Tropical Regions

Ciguatera fish poisoning is a major problem in tropical regions, and may be

the most widespread HAB-generated problem in the world. Caused by

benthic dinoflagellates, toxicity results from bioaccumulation of the toxin in

the food chain. An example can be seen in the benthic dinoflagellate

Gamberdiscus toxicus. The dinoflagellate does not form blooms in the

water column, but lives on the surface of red and brown macroalgae

associated with coral reefs. Herbivorous fish that eat the macroalgae are

eaten by larger fish and so on, until the toxin accumulates in the tissues of

top-predator species that are often the primary foods of local island

inhabitants.

Regional Summary

In conclusion, harmful algal blooms of cyanobacteria, other phytoplankton,

microphytobenthos, some protozoa, and macroalgae are affecting all U.S.

coastal areas. Cyanobacteria and macroalgae are stimulated by excessive

nutrient loading. Although these two HAB groups displace the existing

flora, cyanobacterial blooms are highly sensitive to temperature shifts and

low sunlight, which cause a bloom's rapid demise. On the other hand,

macroalgal blooms are more persistent, and may actually replace seagrass

beds and coral reef systems over the long term.

Photo 10. A bloom of cyanobacteria, formerly known as blue-green

algae, colors this section of the Potomac River bright green.

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Harmful Algal Blooms - Case Studies

Photo 11. The Gymnodinium breve cells shown

here have been magnified 400 times. Blooms of

G. breve are some of the largest ever recorded.

In the Gulf of Mexico they appear to occur

The following are descriptions of two algal genera that form harmful

blooms. One of these species, Gymnodinium breve, is typical of the

Gulf Coast, while the other, Pseudo-nitszchia sp., was only recently

linked to harmful blooms on the West Coast. G. breve has been

intensively investigated for several decades, while information about toxic

Pseudo-nitzschia only began to appear in 1987.

Gymnodinium breve

Gymnodinium breve, unlike some of the other HAB species, has been

well documented in maritime and coastal history, especially in the Gulf of

Mexico region. The earliest recorded fish kill, later attributed to a G.

breve bloom, was in 1844 off the west coast of Florida. Since that time,

recurrent outbreaks have characterized the west Florida and Texas coasts.

In the late 1940s, scientists noticed a number of linkages associated with

this toxic species and derived primarily from effects produced by the

bloom. High cell densities of this toxic dinoflagellate discolor surface

waters with a typical red coloration, producing what has commonly been

referred to as "red tide." However, prior to actually seeing a "red tide,"

beach-goers may experience respiratory problems because cells and

released toxins are inhaled as an aerosol. The toxic aerosol can affect

humans at much lower concentrations than are required for the human eye

to actually see discoloration in the water. G. breve produces brevetoxin,

which is lethal to fish and results in massive fish kills that wash up and

decompose on local beaches. Fish kills can occur before the water is

visibly discolored, at concentrations of ~0.5 million cells per liter.

Exposure to brevetoxin can also cause marine mammal mortalities; in

1996, more than 150 manatees were killed just south of Tampa Bay.

Within the Gulf of Mexico region, these blooms are considered a natural

phenomenon, and have not been attributed to any human factors. It

appears that G. breve bloom dynamics are most closely coupled to

physical processes (Tester and Steidinger 1997). A resident population

exists in the Gulf of Mexico at all times, with background concentrations

of 1 to 1,000 cells per liter. Bloom initiation, transport, and retention are

all strongly affected by the extent of the northward penetration of an

offshore, clockwise current known as the Loop Current, its spinoff

eddies, and its intrusions onto the west Florida shelf. Blooms may

originate around the fronts caused by the flow of the Loop Current along

the outer southwest Florida shelf, approximately 40 to 80 miles offshore

(Mote Marine Laboratory 1998 on-line, Tester and Steidinger 1997).

These fronts are characterized by various nutrient (organic and inorganic)

and light regimes conducive to the growth of G. breve (Steidinger et al.

1998).

Once growth of the algae has been initiated, it may take up to 8 weeks for

the cells (and toxins) to develop in concentrations high enough to kill fish

(Tester and Steidinger 1997). G. breve blooms are some of the largest

recorded, spanning areas of hundreds to thousands of square miles. For

example, a bloom off the coast of Florida in 1964 covered an area of

14,000 square kilometers, from Apalachee Bay to Piney Point. The timing

of G. breve blooms along Florida's western coast is well known, with

occurrences possible throughout the year but most probable in late summer

and fall (Tester and Steidinger 1997). The persistence of a bloom depends

on physical, biological, and chemical conditions and can range from a few

months to more than a year; the longest bloom ever recorded began in

September 1994 and ended in April 1996 in an area from Tarpon Springs

to the Florida Keys (Mote Marine Lab 1998 on-line). Blooms are more

frequent along the west coast of Florida, which has reported blooms

during 23 of the last 24 years, than along the coast of Texas, which has
Harmful Algal Blooms - Case Studies

In the Gu f of Mexico, they appea to occu

naturally and have not been attributed to any

human activities or influences.

experienced only three major blooms, in 1935, 1986, and 1997-1998

(Pinkerton 1998).

The results of these blooms can be both physically and economically

devastating to a region. In April 1963, a bloom that occurred from Tampa

Bay to Marco Island resulted in the deaths of more than 150 tons of fish,

including a 700-pound grouper (Mote Marine Lab 1998 on-line). The red

tide off the coast of Texas and Mexico between October 1997 and January

1998 was responsible for killing more than 14 million fish (Pinkerton

1998); the estimate was later increased to 21 million. These incidents and

others like them have had severe impacts on several industries, including

fisheries (fish and shellfish) and tourism. Blooms have also affected

several other wildlife species, including manatees and birds. Besides the

1996 bloom that killed the manatees, a bloom in the Caloosahatchee River

area of Florida in 1982 resulted in the deaths of 39 manatees (Landsberg

and Steidinger 1998), illustrating the serious impact that these recurrent

natural events can have on an endangered species. To emphasize this, a

red tide now in progress (Fall 1999) off the coast of the Florida panhandle

is believed to be responsible for more than 65 bottlenose dolphin

mortalities since August 1999, when normally one or two are observed

(Rowles 1999).

In Florida, there is strong community awareness and a commitment to

reduce the impacts of these nearly annual events on the western coast.

Researchers from academic, federal, state, and local organizations, as well

as industry and citizen groups, all work to monitor and mitigate the

potential effects of harmful algal blooms. Using remote sensing as well as

sampling cruises, researchers have been able to chart the progression of a

bloom from initiation to senescence. These observations are being used to

develop a forecasting ability for the transport of offshore blooms into

coastal regions (NOAA Coastal Services Center 1998). With this

information, coastal communities will be able to proactively limit the

potential impacts of landfall of these toxic populations and the associated

fish kills that are deposited on recreational beaches.

Pseudo-nitzschia spp.

Pseudo-nitzschia is a long, slender diatom that may produce domoic

acid, the toxin responsible for amnesic shellfish poisoning (ASP).

Members of this diatom genus were first identified as a toxic HAB species

in 1987 in Prince Edward Island, Canada, when 150 people became ill and

three died as a result of eating blue mussels, rich in domoic acid, that had

been harvested locally from Cardigan Bay. In 1988, researchers grew

cultures of the diatom in the lab and measured the production of domoic

acid, thereby making a connection between the toxin found in the poisoned

mussels and a Pseudo-nitzschia multiseries bloom that occurred in the

Cardigan River at the same time (Wright et al. 1989). As a direct result of

this research, Canada began an intense monitoring program to decrease the

harmful effects of Pseudo-nitzschia, and provided the global community

with important information for safeguarding public health.

Photo 12. Blooms of Pseudo-nitzschia produce

domoic acid, a gastrointestinal and neurological poison

that causes amnesic shellfish poisoning and can be

lethal. Because the diatoms do not change the color of

seawater, they are difficult to detect.

While Pseudo-nitzschia blooms and domoic acid have been considered

potential threats to New England waters since the event in Prince Edward

Island in 1987, they were not observed in the United States prior to 1991,

when they appeared on the West Coast. In September 1991, domoic acid

was identified as the causative agent for the deaths of brown pelicans and

cormorants in Monterey Bay, California (Work et al., 1993), and in

November, the toxin was detected in razor clams harvested along the
Harmful Algal Blooms - Case Studies

Oregon and Washington coasts. After the shellfish beds were closed to

harvesting, domoic acid was detected in dungeness crabs, leading to

harvest closures for this species. Similarly high levels of domoic acid,

simultaneous to a bloom of Pseudo-nitzschia pungens, P. multiseries,

and P. australis, were noted in 1994 in mussels sampled from Hood

Canal, Washington (Horner et al. 1997). Poisonings are also highly

probable for coastal Alaskan waters because potentially toxic

Pseudo-nitzschia spp. have been identified and are fairly common in the

region (Horner et al. 1997).

Photo 13. Shellfish that consume Pseudo-nitzschia,

such as these mussels, can accumulate domoic acid in

their viscera and flesh. In turn, the birds, mammals, and

people that eat them may fall ill with amnesic shellfish

poisoning (ASP). Some human victims never fully

recover from the short-term memory loss that is a

classic symptom of ASP.

A recent outbreak of domoic-acid poisoning occurred in May 1998, when

many apparently well fed sea lions washed ashore along the coast of

California from San Luis Obispo to Santa Cruz (Northwest Fisheries

Science Center 1998 on-line). The animals exhibited signs of physical

distress, including frothing at the mouth, violent seizures, and vomiting.

By the end of June, more than 40 of the sick animals had died.

Postmortem analyses revealed microscopic lesions in the hippocampus

region of the brain, previously identified as characteristic of domoic-acid

poisoning; domoic acid was also detected in the urine of some of the

affected animals. The incident has been postulated to be the result of a

Pseudo-nitzschia australis bloom that was first observed off Santa Cruz

on May 11, 1998 (NWFSC 1998 on-line).

Using regular cruises for monitoring and sampling, scientists are

attempting to understand the environmental, chemical, and physical factors

that trigger the accumulation of the domoic acid-producing species, as well

as the factors that induce their toxicity. To date, five species found on the

U.S. West Coast have been shown to produce domoic acid: P.

multiseries, P. australis, P. pseudodelicatissima, P. pungens, and P.

seriata (Horner et al. 1997). To the dismay of coastal managers

everywhere, these species have global distributions, and pose potentially

deadly threats to coastal living resources and the people who live, work,

and recreate in coastal regions.

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Harmful Algal Blooms - Expert Interpretation

The three individuals below are experts in the topic of harmful algal blooms.

Here they voice their opinions on two questions relevant to that topic.

Question 1. Are there significant linkages between land-based

activities and harmful algal blooms?

Question 2. Are there strategies to control, mitigate, and

ultimately eliminate the outbreaks and health impacts of

harmful algal blooms?

Experts

Donald M.

Anderson

Fran Van Dolah Jonathan Sharp
Harmful Algal Blooms - Expert Interpretation

Donald M. Anderson

Senior Scientist, Biology Department,

Woods Hole Oceanographic

Institution

Since the late 1970s, Dr. Anderson has been studying the physiology and

genetic regulation of toxicity in dinoflagellates, their bloom dynamics and

ecology, and the global biogeography of toxic Alexandrium species. He is

heavily involved in national and international program development for

research and training on red tides, marine biotoxins, and harmful algae. He

serves as the Director of the U.S. National Office for Marine Biotoxins and

Harmful Algae, located at the Woods Hole Oceanographic Institution.

Response to Question 1

Response to Question 2

(top)

Question 1. Are there significant linkages between land-based

activities and harmful algal blooms?

Click here for audio response

There are some very clear linkages between land-based activities and harmful

algal blooms (HABs). Many HABs occur in relatively pristine waters, and

show no influence from pollution or other human activities. On the other

hand, some of these phenomena show strong linkages to activities such as

pollution, which provides nitrogen and phosphorus to the algal cells which

use these nutrients to become more abundant. HAB scientists generally

accept that enrichment of coastal waters results in an enhancement of many

algal species, only some of which are harmful or toxic. The most recent

example of the linkage between pollution and a HAB event is with the

Pfiesteria outbreaks in North Carolina and Maryland, where the causative

species is found predominantly in areas receiving runoff from hog and

chicken farms. Other human activities which have been linked to HABs

include ballast water introduction of species as a result of international

shipping. Another example is aquaculture, which tends to put farmed

fisheries resources in locations which then become the sites of HAB

outbreaks--either because those resources are carefully monitored for toxins,

or because, in some instances, the aquaculture facilities enrich the

surrounding waters with nutrients through over-feeding and waste that then

stimulate HABs.

(top)

Question 2. Are there strategies to control, mitigate, and

ultimately eliminate the outbreaks and health impacts of

harmful algal blooms?

Click here for audio response

There are a number of strategies that are either used, or are under

investigation that can reduce the impacts from harmful algal blooms (HABs).

Some of these are practical and widely accepted, while other are highly

controversial and untested. An example of the former would be the routine

monitoring programs for toxins in shellfish that keep dangerous products off

the market. Another would be strategies to tow fish (aquaculture) cages out

of the path of approaching toxic blooms. Long-term mitigation strategies

include the reduction of pollution inputs to coastal waters, one effect of

which is likely to be a reduction in the number and severity of HAB

outbreaks. A more controversial approach to mitigation involves efforts to

directly intervene in the bloom process-i.e., to target the HAB organism

itself. This approach is quite common on land in the fight against terrestrial

pests, but is seldom used in the ocean against "marine pests" because of

concerns about environmental impacts. Nevertheless, scientists are now

exploring direct control strategies along several lines. One is biological

control, whereby bacteria, viruses, parasites, and other pathogens might be

used to control a particular HAB species. Another approach involves the use

of chemicals or natural materials such as clays which can alter the abundance

of cells in a HAB population. This area of HAB research is in its infancy.

(top)
Harmful Algal Blooms - Expert Interpretation

Fran Van Dolah

Research Biochemist, Center for

Coastal Environmental Health and

Biomolecular Research, National

Ocean Service, NOAA

Dr. Van Dolah has been with NOAA's Marine Biotoxins Program for eight

years, where her research has focused in two areas. First is the development

of rapid assays for a variety of marine biotoxins in seawater, algae, seafood,

and marine mammals. The second is research on cellular and molecular

mechanisms regulating growth and cell division in toxic dinoflagellates.

Response to Question 1

Response to Question 2

(top)

Question 1. Are there significant linkages between land based

activities and harmful algal blooms?

Click here for audio response

Anthropogenic impacts on coastal waters do appear in some instances to

contribute to the occurrence of algal blooms. However, the diversity of

organisms collectively termed "harmful algae", and the diversity of life

history strategies these organisms have evolved, make broad generalizations

inappropriate. For example, blooms of two of the most problematic

dinoflagellates in U.S. coastal waters, Alexandrium spp. , responsible for

paralytic shellfish poisoning on the northeast and west coasts, and

Gymnodinium breve , responsible for neurotoxic shellfish poisoning in the

Gulf of Mexico, initiate offshore in oligotrophic waters. These species are

well adapted for growth in low nutrient conditions and there is no

compelling evidence to suggest that nutrient input into coastal waters

contributes to their bloom formation. However, in other cases increased

nutrient loading clearly does correlate with increases in the incidence of

HABs. Between 1965 and 1976, a 6-fold increase in the population of Hong

Kong was accompanied by a 2.5-fold increase in nutrient loading and an

8-fold increase in the frequency of HABs. Agricultural runoff of phosphorus

is known to stimulate cyanobacterial blooms. However, a more complex

picture is emerging which suggests that changes in chemical forms of

nutrients and nutrient ratios may be equally important as total nutrient

loading in coastal waters. Increases in phosphate, for example, may result in

silica-limited conditions that favor nuisance flagellates over diatoms. Coastal

development may also cause shifts in phytoplankton communities by altering

concentrations of natural organic chelators present in drainage from forested

areas, as these areas become urbanized or cleared for agricultural use.

(top)

Question 2. Are there strategies to control, mitigate, and

ultimately eliminate the outbreaks and health impacts of

harmful algal blooms?

Click here for audio response

Harmful algal blooms are currently not managed sufficiently. Management

options include prevention, control, and mitigation. Prevention is directed at

minimizing anthropogenic impacts that may contribute to bloom formation.

Legislated reductions in chemical and nutrient inputs, for example, have

successfully reduced algal growth in certain cases. However, these strategies

do not address all HABs, including those that initiate offshore. Control

strategies include chemical or biological agents that target a bloom, once

initiated. These are not currently employed in the U.S., and have been

approached with caution for a number of reasons. Most important is the

potential for adverse effects such strategies may have on coastal ecosystems.

We currently lack sufficient insight into mechanisms regulating blooms of

any HAB species to implement effective species-specific controls. In the

case of dinoflagellates which historically form episodic blooms, it is not

clear that control of blooms is even desirable, since the role these blooms

play in their respective ecosystems is not known. Thus, while control

strategies may hold great potential, insight into the ecophysiology of HAB

species is necessary to support their design and rigorous testing for adverse

effects is essential prior to implementation. Mitigation encompasses diverse

efforts to minimize HAB impacts, and is currently the major management

strategy employed. Among these, shellfish and phytoplankton monitoring

programs have been highly successful in protecting public health. A

promising new approach, to which significant research is currently directed,

is development of forecasting capabilities. Forecasting holds promise as a

strategy to mitigate economic and environmental impacts of HABs.
Harmful Algal Blooms - Expert Interpretation

Jonathan Sharp

Professor, The Graduate College of

Marine Studies, University of

Delaware

Professor Sharp joined the faculty of the University of Delaware in 1973.

For the past 25 years, he has conducted fieldwork primarily in mid-Atlantic

coastal waters and in the Delaware Estuary. His research emphasis is in

biogeochemical studies of the dynamics of plant nutrients, dissolved and

particulate organic matter, and microbial (phytoplankton and bacteria)

interactions. He also conducts research in measuring dissolved organic

carbon and nitrogen in the ocean. Professor Sharp served as Chair of the

Scientific and Technical Advisory Committee for the Delaware Estuary

Program and currently is Vice-chairman of the Board of Directors of the

non-profit Partnership for the Delaware Estuary. 

Question 1. Are there significant linkages between land based

activities and harmful algal blooms?

Click here for audio response

My answer is a qualified "No". There is evidence of massive harmful algal

blooms (HABs) occurring long before human land-based activities altered

the coastal oceans. In addition, the HABs often occur slightly distant from

the areas of maximum land-based inputs. While there are suggestions that

the frequency and intensity of HABs have increased in recent years, these

are based on circumstantial evidence, not on significant causal evidence. On

the other hand, land-based activities have increased loadings to estuaries and

coastal oceans of nutrients and other excess materials from agricultural,

industrial, and municipal activities. Human activities have also greatly altered

the physical nature of estuarine and coastal habitats. As a consequence, the

chemical composition of the coastal environment has been changed. Since

inputs have greatly increased concentrations of nitrogen and phosphorus

nutrients, there is reason to expect associations between nutrients and algal

populations. However, we must recognize that there are changes not only in

overall concentrations, but also in ratios of nitrogen to phosphorus, to

silicon, and to numerous trace elements. In addition, trace metal and organic

chemical compounds serve as contaminants with potential negative impacts

on coastal ecosystems. Overall, the chemistry of nearshore ocean waters has

changed from land-based activities and these changes probably contribute to

ecosystem nature and function being altered. However, we do not

sufficiently understand the complex ecosystem responses (including algal

growth, species changes, and food web transfer) to link inputs from

land-based activities to specific responses, such as HABs.

(top)

Question 2. Are there strategies to control, mitigate, and

ultimately eliminate the outbreaks and health impacts of

harmful algal blooms?

Click here for audio response

I am aware of some actions have been taken to minimize health impacts of

HABs that appear to be appropriate. However, I do not feel that adequate

strategies to control, mitigate, and eliminate outbreaks are in place. It is not

feasible to develop accurate strategies for a problem when the problem is

inadequately described. Far more attention must be addressed on why HAB

outbreaks do not occur in some areas when they do in others. For many

years, we have recognized HAB problems, including numerous human

deaths; but we have dedicated very little research to understanding HABs.

Recently, public and political concern has directed some funding toward

HAB monitoring, research, and mitigation. Much of this concern has been

stimulated by publicity on Pfiesteria , a relatively minor HAB problem.

Unfortunately, some of the monitoring and most of the mitigation is

predicated on the assumption that we understand more about the problem

than we actually do. Also, emphasis on Pfiesteria has been

disproportionate when compared to other HAB problems. A main target has

been nutrient runoff controls. In attempts to control nutrient runoff, we will

also control other chemical runoff into estuarine and coastal waters and this

may be a beneficial action. However, if a specific nutrient (i.e., nitrogen or

phosphorus) is not the specific cause of a HAB outbreak, unrealistic

expectations will be made for the impact from such controls. If we really

wish to control HABs, we must invest more funding in research that is not

constrained by preconceived ideas.

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Harmful Algal Blooms - References

Text References

On-line References

Text References

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the northwestern United States. Limnology and Oceanography

42:1009-1022.

Anderson, D.M. 1995. ECOHAB, the ecology and oceanography of

harmful algal blooms: A national research agenda. Woods Hole, MA:

Woods Hole Oceanographic Institution. 66 pp.

Anderson, D.M., S.B. Galloway, and J.D. Joseph. 1993. Marine

biotoxins and harmful algae: A national plan. Woods Hole Oceanographic

Institution technical report WHOI 93-02. Woods Hole, MA: Woods Hole

Oceanographic Institution. 59 pp.

Baden, D.G. 1998. Center for Marine Science Research, University of

North Carolina Wilmington, Wilmington, NC. Personal communication.

Boesch, D.F., D.A. Anderson, R.A. Horner, S.E. Shumway, P.A.

Tester, and T.E. Whitledge. 1997. Harmful algal blooms in coastal waters:

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National Fish and Wildlife Federation. Silver Spring, MD: NOAA, Coastal

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Carmichael, W. 1997. The cyanotoxins. Advances in Botanical Research

27:211-256.

Caron, D.A., E.L. Lim, J. Kunze, E.M. Cosper, and D.M. Anderson.

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phytoplankton blooms: Causes and impacts of recurrent brown tides and

other unusual blooms. Berlin: Springer-Verlag. pp. 265-294.

Chotiyaputta, C. and K. Hirayama. 1978. Food selectivity of the rotifer

Brachionus plicatilis feeding on phytoplankton. Marine Biology

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Dahl, E. and K. Tangen. 1990. Gyrodinium aureolum bloom along the

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Press. pp. 123-127.
Harmful Algal Blooms - References

Hallengraeff, G.M. 1993. A review of harmful algal blooms and their

apparent global increase. Phycologia 32:79-99.

Horner, R.A., D.L. Garrison, and F.G. Plumley. 1997. Harmful algal

blooms and red tide problems on the U.S. West Coast. Limnology and

Oceanography 42:1076-1088.

Kononen, K. and S. Nommann. 1992. Spatio-temporal dynamics of the

cyanobacterial bloom in the Gulf of Finland. In: Carpenter, E.J., D.G.

Capone, and J.G. Rueter (eds.), Marine pelagic cyanobacteria:

Trichodesmium and other diazotrophs. The Netherlands: Kluwer Academic

Publishing. pp. 95-114.

Lam, C.W.Y. and K.C. Ho. 1989. Red tides in Tolo Harbour, Hong

Kong. In: Okaichi, T., D.M. Anderson, and T. Nemato (eds.), Red tides:

Biology, environmental science, and toxicology, proceedings of the first

international symposium on red tides. New York: Elsevier Press. pp.

49-52.

LaPointe, B.E. 1997. Nutrient thresholds for bottom-up control of

macroalgal blooms on coral reefs in Jamaica and southeast Florida.

Limnology and Oceanography 42:1119-1131.

Lindahl, O. 1986. Offshore growth of Gyrodinium

aureolum (Dinophyceae)--The cause of coastal blooms in the Skagerrak

area? Sarsia 71:27-33.

Okaichi, T. 1989. Red tide problems in the Seto Inland Sea, Japan. In:

Okaichi, T., D.M. Anderson, and T. Nemato (eds.), Red tides: Biology,

environmental science, and toxicology, proceedings of the first

international symposium on red tides. New York: Elsevier Press. pp.

137-144.

Pazos, Y., F.G. Figueiras, X.A. Alvarez-Salgado, and G. Roson. 1995.

Hydrographic situations and species associated with the appearance of

Dinophysis acuta and their probable cysts in the Ria de Arousa. In:

Lassus, P. et al. (eds.), Harmful algal blooms. Paris: Lavoisier. pp.

651-656.

Pinkerton, J. 1998 (on-line). Red tide may be a killer we must learn to live

with: Detection, warning may be most we can hope for in fighting algal

blooms. The Houston Chronicle.

http://www.redtide.whoi.edu/hab/notedevents/Texas/Texasbreve1-5.html

Rowles, T. 1999. National Marine Fisheries Service, National Oceaninc

and Atmospheric Administration. Silver Spring, MD. Personal

communication.

Scholin, C.A. and D.A. Anderson. 1993. Population analysis of toxic and

nontoxic Alexandrium species using ribosomal RNA signature sequences.

In: Smayda, T.J. and Y. Shimizu (eds.), Toxic phytoplankton blooms in

the sea. Amsterdam: Elsevier Press. pp. 95-102.

Sellner, K.G. 1992. Trophodynamics of marine cyanobacteria blooms. In:

Carpenter, E.J., D.G. Capone, and J.G. Rueter (eds.), Marine pelagic

cyanobacteria: Trichodesmium and other diazotrophs. The Netherlands:

Kluwer Academic Publishing. pp. 75-94.

Shumway, S.E. 1988. A review of the effects of algal blooms on shellfish

and aquaculture. Journal of the World Aquaculture Society 21:65-104.

Sieling, W. and D. Lipton. 1998 (on-line). Pfiesteria's impact on

seafood industry sales.

http://www.mdsg.umd.edu/fishhealth/pfiesteria/pfeconomics/index.html.

Smayda, T.J. 1997. What is a bloom? A commentary. Limnology and

Oceanography 42:1132-1136.

Smayda, T.J. 1990. Novel and nuisance phytoplankton blooms in the sea:

Evidence for a global epidemic. In: Graneli, E., B. Sundstrom, L. Edler,

and D.M. Anderson (eds.), Toxic marine phytoplankton. New York:

Elsevier Press. pp. 29-40.

Smayda, T.J. and T. Villareal. 1989. An extraordinary, noxious brown

tide in Narragansett Bay. 1. The organism and its dynamics. In: Okaichi,

T. et al. (eds.), Red tides: Biology, environmental science, and toxicology,

proceedings of the first international symposium on red tides. New York:

Elsevier Press. pp. 129-132.

Subba Rao, D.V., M.A. Quilliam, and R. Pocklington. 1988. Domoic
Harmful Algal Blooms - References

acid--a neurotoxic amino acid produced by the marine diatom Nitzschia

pungens in culture. Canadian Journal of Fisheries and Aquatic Sciences

45:2076-2079.

Taylor, F.J.R. 1987. The biology of dinoflagellates. Oxford: Blackwell

Scientific Publications.

Tester, P.A. and P.K. Fowler. 1990. Brevetoxin contamination of

Mercenaria mercenaria and Crassostrea virginica: A management

issue. In: Graneli, E., B. Sundstrom, L. Edler, and D.M. Anderson (eds.),

Toxic marine phytoplankton. New York: Elsevier Press. pp. 499-503.

Tester, P.A. and K.A. Steidinger. 1997. Gymnodinium breve red tide

blooms: Initiation, transport, and consequences of surface circulation.

Limnology and Oceanography 42:1052-1075.

Turgeon, D.D., K.G. Sellner, D. Scavia, and D. Anderson. 1998. Status

of U.S. harmful algal blooms: Progress towards a national program. Silver

Spring, MD: NOAA, National Ocean Service, Centers for Coastal Ocean

Science, Center for Monitoring and Assessment. 22 pp.

Turner, J.T. and P.A. Tester. 1997. Toxic marine phytoplankton,

zooplankton grazers, and pelagic food webs. Limnology and

Oceanography 42:1203-1214.

U.S. Environmental Protection Agency. 1998. What you should know

about Pfiesteria piscicida. Washington, DC: U.S. Government Printing

Office.

Valiela, I., J. McClelland, J. Hauxwell, P.J. Behr, D. Hersh, and K.

Foreman. 1997. Macroalgal blooms in shallow estuaries: Controls and

ecophysiological and ecosystem consequences. Limnology and

Oceanography 42:1105-1118.

Whitton, B.A. 1982. The biology of cyanobacteria. Berkeley: University

of California Press.

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On-line References

The following references were accessed via URL on the World Wide Web

during 1998 and 1999.

Note: Harmful algal blooms (HABs) are a topic of national concern. The

Web references presented here are intended to provide supplementary

information related to the text of this essay. These references also supply

links to many additional sites.

Algal Species

Alg@line Data Base.

http://meri.fimr.fi/Algaline/eng/EnAlgaline.nsf?OpenDatabase

Includes a database of harmful algal blooms in the Baltic, Bothnian, Åland,

and Archipelago seas and the Gulf of Finland along with a photo gallery of

hundreds of species of phytoplankton. The Web site is produced in

cooperation with various Finnish and Estonian research and scientific

institutes.

Congressional Research Service. Pfiesteria and related harmful blooms:

Natural resource and human health concerns.

http://www.cnie.org/nle/mar-23.html#Federal Response

Provides detailed information on what Pfiesteria is, water quality

conditions related to blooms, interactions with the environment, and effects

on human health and living aquatic resources. Also discusses state and
Harmful Algal Blooms - References

federal agencies' responses to the problem.

Florida Marine Research Institute. ECOHAB: Florida. HAB species.

http://www.fmri.usf.edu/ecohab/subsalsa.htm

Discusses in detail eight separate algal species, including information about

distribution, habitat, toxins, ecological impacts, impacts on animals, human

health, and associated types of shellfish poisoning.

North Carolina State University. Aquatic Botany Laboratory, Pfiesteria

piscicida page.

http://www2.ncsu.edu/unity/lockers/project/aquatic_botany/pfiest.html

Provides detailed information on Pfiesteria piscicida, including life

cycle, effects on fish and shellfish, and impacts on human health.

University of Calgary. Dinoflagellates.

http://www.geo.ucalgary.ca/~macrae/palynology/dinoflagellates/

dinoflagellates.html

Provides general information on several dinoflagellate species, including

basic anatomy; includes diagrams and scanning electron microscope

images.

University of California at Berkley. Introduction to the Bacillariophyta

(diatoms).

http://www.ucmp.berkeley.edu/chromista/bacillariophyta.html

Provides detailed information on the life history, ecology, morphology,

and systematics of the diatoms.

University of California at Berkley. Introduction to the Dinoflagellata.

http://www.ucmp.berkeley.edu/protista/dinoflagellata.html

Provides detailed information on the life history, ecology, morphology,

and systematics of the dinoflagellates.

Woods Hole Oceanographic Institution. Species responsible for harmful

algal blooms.

http://habserv1.whoi.edu/hab/species/species.html

Briefly describes various HAB species; includes detailed photos.

Bloom Detection.

National Aeronautics and Space Administration. Plankton blooms: The

good, the bad, and the shiny.

http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/OCDST/classic_scenes/

12_classics_blooms.html

Contains general information on detecting blooms using ocean color data

from the Coastal Zone Color Scanner satellite.

Region-specific Information

National Marine Fisheries Service, Northwest Fisheries Science Center.

Harmful algal bloom and marine biotoxin pages.

http://www.nwfsc.noaa.gov/hab/

Provides information on HAB biology, including the mechanisms that

cause them to spread, toxin detection, and protection of public health. HAB

issues for the West Coast and Alaska are highlighted, with details on

paralytic shellfish poisoning, domoic acid poisoning, heterosigma

problems, and diarrheic shellfish poisoning. Also includes an on-line
Harmful Algal Blooms - References

version of The West Coast Marine Biotoxin and Harmful Algal Bloom

Newsletter.

Mote Marine Laboratory. About red tide.

http://www.marinelab.sarasota.fl.us/~mhenry/rtchrono.phtml

Offers information about red tide in Florida, including updates on current

blooms and closed shellfish areas. Also includes a historical chronology of

red tide along Florida's Gulf Coast.

Texas Parks and Wildlife. Frequently asked questions about red tide.

http://www.tpwd.state.tx.us/fish/recreat/redtide.htm

Offers general information on red tide in Texas, including information on

Gymnodinium breve blooms and associated shellfish-area closures.

Woods Hole Oceanographic Institution. ECOHAB: Gulf of Maine.

http://crusty.er.usgs.gov/ecohab/

Offers information about HABs in the Gulf of Maine, including data and

the locations of toxicity monitoring stations.

Status and Trends

Anderson, D.M.1995. Toxic red tides and HABs, a practical challenge in

coastal oceanography. U.S. national report to IUGG, 1991-1994. Review

of Geophysics, vol. 33 supplement, American Geophysical Union.

http://www.agu.org/revgeophys/anders01/anders01.html

Discusses recent trends, causative factors, nutrient dynamics, emerging

technologies, and management and policy issues. Includes an extensive

bibliography of published literature.

U.S. Environmental Protection Agency. National harmful algal bloom

research and monitoring strategy: An initial focus on Pfiesteria, fish

lesions, fish kills and public health.

http://www.epa.gov/nep/pfiesteria/fish2.html

Describes federal agencies' efforts to develop and coordinate a long-term

national strategy for federally supported research and monitoring on

problems associated with HABs, particularly Pfiesteria and

Pfiesteria -like species.

Woods Hole Oceanographic Institution. The harmful algae page.

http://habserv1.whoi.edu/hab/

Contains maps of current HAB locations and trends; provides information

on HABs, including introductory material on what algal blooms are and

how they form, characteristics of various harmful species, and the adverse

impacts of blooms. Includes recent news coverage about current HAB

outbreaks.

Toxins

Florida Marine Research Institute. ECOHAB: Florida. Seafood poisonings.

http://www.fmri.usf.edu/ecohab/poison.htm

Provides detailed information on the various toxins produced by HABs, the

factors affecting toxicity, the symptoms and diagnosis of human illnesses,

and the types of seafood that cause illness.

U.S. Food and Drug Administration, Center for Food Safety and Applied

Nutrition. Various shellfish-associated toxins.

http://vm.cfsan.fda.gov/~mow/chap37.html
Harmful Algal Blooms - References

Briefly discusses shellfish-associated algal toxins, detection of toxicity in

shellfish, the symptoms, effects and diagnosis of shellfish poisoning, and

past outbreaks.

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Harmful Algal Blooms - Appendices

Appendix A Known HAB Toxins and Effects
Harmful Algal Blooms - Appendix A

Appendix A

Return to Appendices

Return to Introduction

Known HAB Toxins and Effects

Type of Poisoning Symptoms Course of Disease

 

Ciguatera Fish Poisoning (CFP) is caused by several

different toxins, including ciguatoxin, scaritoxin,

maitotoxin, and okadaic acid. Some of these toxins are

known to be produced by the dinoflagellate

Gamberdiscus toxicus, which is naturally found in

subtropical and tropical regions and is eaten by herbivorous

fish.

Gastrointestinal: diarrhea, vomiting,

abdominal pain

Neurological: headache, reversal of hot and

cold sensations, vertigo, muscular weakness,

numbness

Cardiovascular: irregular heart rhythm,

lowered blood pressure

There is no antidote for this type of poisoning.

It is usually self-limiting and symptoms

subside within several days, usually without

lasting side effects. Initial signs of poisoning

occur within six hours after ingestion.

Paralytic Shellfish Poisoning (PSP) is caused by

more than 20 different saxitoxins, which are produced by

members of the genus Alexandrium. Saxitoxins

accumulate in shellfish (primarily mussels, clams, cockles,

and scallops), which are filter feeders. In turn, people and

animals may be affected after consuming the shellfish.

Neurological: respiratory paralysis, tingling,

burning, numbness, drowsiness, incoherent

speech, rash)

There is no antidote for PSP, which may be

considered life threatening if the victim does

not receive proper medical support. Recovery

usually occurs within 24 hours of onset

without lasting side effects. The onset of

symptoms is rapid (one-half to two hours after

ingestion) and depends on the amount of toxin

consumed. Death can occur if the victim has

consumed a large amount of the toxin and if

respiratory paralysis occurs. With medical

support, the victim usually recovers within 12

hours.

Diarrheic Shellfish Poisoning (DSP) is thought to be

caused by several toxins, including yessotoxin, dinophysis

toxins, pectenotoxins, and okadaic acid. Some of these

toxins are known to be produced by Dinophysis

sp., which is filtered by shellfish (primarily oysters,

scallops and mussels). DSP is prevalent in Europe and has

been seen in eastern Canada; it has not been reported in the

United States.

Gastrointestinal: nausea, vomiting, diarrhea,

abdominal pain, chills, headache, fever

There is no antidote, but recovery normally

occurs within three days of onset without

lasting side effects. Onset is rapid, occurring

one-half to two hours after ingestion.

Amnesic Shellfish Poisoning (ASP) is caused by

domoic acid, which is produced by several members of the

diatom genus Pseudo-nitzschia. Domoic acid accumulates

in the animal's viscera; in some cases (e.g., razor clams), it

also accumulates in the flesh.

Gastrointestinal: nausea, vomiting, abdominal

cramps, diarrhea)

Neurological: dizziness, headache, seizures,

disorientation, short-term memory loss,

respiratory difficulty, coma

There is no antidote, and the disease may be

considered life threatening. The onset of

gastrointestinal symptoms begins within 24

hours of ingestion, and neurological symptoms

occur within 48 hours. In many cases,

recovery from ASP is never complete, because

many victims suffer short-term memory loss.

Neurotoxic Shellfish Poisoning (NSP) is caused by

brevetoxins produced by the dinoflagellate Gymnodinium

breve. It has been found to be associated with shellfish

harvested along Florida and in the Gulf of Mexico.

Gastrointestinal: diarrhea, vomiting

Neurological: tingling and numbness of lips,

tongue, and throat, muscle aches, dizziness,

reversal of hot and cold sensations

There is no antidote, but recovery normally

occurs within hours to several days of onset

with few aftereffects. Onset is rapid, occurring

within minutes to a few hours after ingestion.

Cyanobacterial poisoning is caused by a variety of

toxins, including microcystins and anatoxins. They are

produced by different species of cyanobacteria, including

Anabaena sp., Aphanizomenon sp., and Microcystis sp.

Neurological: derangement, staggering,

tremors

Hepatological: induced liver failure, abdominal

pain

There are no known antidotes for

cyanobacterial poisoning. Currently, it is not

known which dosages trigger certain responses

(Carmichael 1997). Death may occur due to

liver failure (Carmichael 1997).

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Return to Appendices

Return to Introduction
Harmful Algal Blooms - Glossary

algae: a diverse group of chiefly aquatic plants (e.g., seaweed, pond

scum, stonewort) that contain chlorophyll but lack roots, stems, leaves,

and vascular tissues, and may passively drift, weakly swim, grow on a

substrate, or take root in a water body.

anoxic: devoid of dissolved oxygen.

benthic: pertaining to organisms living in or on the bottom of aquatic

environments (e.g., polychaetes, clams, snails).

biodiversity (species diversity): the variety of species found in a

particular habitat.

cyanobacteria (also blue-green algae): bacteria that contain

chlorophyll a (a pigment used for photosynthesis) and are able to

photosynthesize.

diatom: any of numerous microscopic, one-celled, marine and freshwater

algae having cell walls that contain silica; diatoms are a food source for all

kinds of marine life.

dinoflagellates: an order of protozoans that are members of the order

Dinoflagellida. They typically have two flagella, one that propels water to

the rear and another that rotates the body. Some dinoflagellates can

photosynthesize, while others are strictly heterotrophic.

domoic acid: a naturally occurring neurotoxic amino acid that can disrupt

the transmission of impulses from cell to cell.

embayment (bay): an inlet of the sea or other water body, usually

smaller than a gulf, that has reduced or restricted water exchange with the

larger body of water to which it is connected.

flagellate: a cell or organism capable of motion through flagellar

(whiplike) activity.

genetically similar populations: populations of organisms that

contain DNA sequences that are similar to one another.

genus (pl. genera): one of the major taxonomic groups used to

scientifically classify plants and animals. Several closely related species

make up a genus; several genera make up a family.

grazer: organisms that eat primary producers (e.g., phytoplankton).

habitat: the living place or "home" of a particular organism or biological

community.

heterotrophic: an organism capable of sustained growth on an organic

substrate in the dark.

hypoxia: low concentrations of dissolved oxygen in the water, usually

ranging between 0 and 2 milligrams per liter.

invertebrates: animals lacking a spinal column (e.g., crabs, lobsters,

shrimp).

loop current: the dominant circulating water mass in the Gulf of Mexico,

which enters through the Yucatan Strait (between the Yucatan Peninsula

and Cuba) and extends northward, eastward, and then southward, where it

exits through the Straits of Florida (between the Dry Tortugas and Cuba,

where it is known as the Florida current). The loop current is known to

extend far to the north and occasionally to intrude on the continental shelf

of the north-central Gulf, at speeds of 127 to 177 centimeters per second.

Large, clockwise-rotating portions of the loop current, called "eddies,"
Harmful Algal Blooms - Glossary

occasionally break off from the main current. These eddies spin westward

toward the Texas coast, carrying vast amounts of water and marine life into

the western Gulf.

monitoring: periodic measurements of the same parameters, physical or

biological, designed to detect changes over time.

nutrient enrichment: an increase in the amount of nutrients added to an

ecosystem, above normal levels; pollution occurs when damaging amounts

of nutrients are added.

nutrients: inorganic chemicals (particularly nitrogen, phosphorus and

silicon) required for the growth of phytoplankton.

photosynthesis: the transformation of carbon dioxide and water to

organic compounds (e.g., sugars) using sunlight as energy.

phytoplankton: minute aquatic plants and animals (e.g., algae), usually

containing chlorophyll, that passively drift or weakly swim in a water

body. Although zooplankton and other filter feeders eat phytoplankton,

huge populations, called blooms, sometimes build up and can damage

marine life and the environment.

planktonic: pertaining to plankton, minute aquatic plants and animals

(e.g., algae) that passively drift or weakly swim in a water body.

predation: feeding upon other organisms.

protozoa: one-celled organisms.

pycnocline: the region of the water column characterized by the strongest

vertical gradient in density, attributable to temperature, salinity, or both.

runoff: water that travels along impervious surfaces (e.g., streets, parking

lots), usually after rain events, and empties into streams and nearshore

environments. Runoff can contain substantial amounts of contaminants

from urban and agricultural land uses (e.g., sewage pollution, fertilizer

from lawns and agriculture, pesticides.)

nonpoint urban runoff: precipitation-related discharge of septic

leachate, animal wastes, etc. from impervious surfaces, lawns, and other

urban land uses.

sediment: particulate material lying on the sea floor (e.g., sand, gravel,

silt, mud).

toxin (also biotoxin): a poisonous substance that is specifically

produced by the metabolic activities of a living organism.

zooplankton: very small animals that drift or float passively with the

current in water bodies.

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Harmful Algal Blooms - Credits

Acknowledgements

Photo Credits

About the Authors

Acknowledgements

There are several individuals that made this report a reality. First, we would

like to thank the people of the National Ocean Service, Special Projects

Office, for their tireless efforts in creating this web series. Second, we

would like to thank the Coastal Ocean Program within the National Ocean

Service where one of the authors, Karen Bushaw-Newton, served her

fellowship term. Finally, we would like to thank all the individuals who

provided their expertise, photos, diagrams, and/or other types of input to

this report. These include: D. Anderson, F. Van Dolah, T. Smayda, J.

Sharp, P. Tester, D. Turgeon, D. Baden, V. Trainer, K. Steidinger, and S.

Hällfors.

(top)

Photo Credits

Many of the photos were gathered from NOAA archives or were

generously provided from personal collections of NOAA staff members.

Others were contributed from outside of NOAA, and we gratefully thank

the following institutions and individuals:

Photo 1. Peter Franks

Photo 2. Joann Burkholder

Photo 3. Baltic Sea Alg@Line Web site

Photo 4. Woods Hole Oceanographic Institute, The Harmful Algal Page

Web site

Photo 6. Brian LaPointe

Photo 7. S. Hall

Photo 8. U.S. Geological Survey

Photo 9. Dr. Pat Tester, NOAA and Dr. Wayne Litaker, University of

North Carolina, Chapel Hill

Photo 10. W. Bennett, U.S. Geological Survey

Photo 12. Carla Stehr

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Harmful Algal Blooms - Credits

About the Authors

Karen L. Bushaw-Newton was a 1998 Knauss Sea Grant Fellow with NOAA's

Center for Sponsored Coastal Ocean Research. She has a bachelor's of science in

microbiology and a PhD in ecology from the University of Georgia. Dr.

Bushaw-Newton has many research interests, including the biogeochemical

cycling of organic matter in both freshwater and marine wetlands; the delineation,

mitigation, and restoration of wetland habitats; and the use of wetlands as natural

filtering systems for the control of excess nutrients and pollutants.

After 20 years as an active member of the plankton research community, Kevin

Sellner recently joined NOAA's Center for Sponsored Coastal Ocean Research.

He has focused his research over the last decade on the ecology of harmful algal

blooms, and specifically on the fate of bloom production in coastal and oceanic

systems. His primary interest has been to determine the importance of

zooplankton grazing in blooms, but has also addressed the roles of sedimentation

and microbial heterotrophy in bloom dissipation. Kevin has studied blooms from

the Peruvian upwelling system, to the subestuaries of the Chesapeake Bay, to the

enclosed Baltic Sea/Gulf of Finland. In his role at NOAA, he serves as the

coordinator for the interagency research program known as ECOHAB (Ecology

and Oceanography of Harmful Algal Blooms).

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Harmful Algal Blooms - Figure 1

Return to Introduction

Figure 1. Worldwide HABs distribution, 1544-1997

Source: D.G. Baden, 1998

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Return to Introduction
Harmful Algal Blooms - Figure 2

Return to National Picture

Figure 2. Location of HAB-related events in U.S. coastal waters before and after

1972

Source: National Office for Marine Biotoxins and Harmful Algal Blooms, 

Woods Hole Oceanographic Institute; Turgeon et al. 1998.

Abbreviations: NSP, neurotoxic shellfish poisoning; PSP, paralytic shellfish poisoning;

ASP, amnesic shellfish poisoning; DSP, diarrheic shellfish poisoning

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Return to National Picture
Harmful Algal Blooms - Figure 3

Return to National Picture

Figure 3. Effects of HABs

(top)

Return to National Picture
Harmful Algal Blooms - Figures 4-7 Index

Figure 4-7 Index

Return to Regional Contrasts

Click on the image or the figure title to view the full size image.

Figure 4. Ciguatera fish poisoning (CFP) in the coastal

United States, 1988-1998

Figure 5. Paralytic shellfish poisoning (PSP) in the

coastal United States, 1988-1998

Figure 6. Amnesic shellfish poisoning (ASP) in the coastal

United States, 1988-1998

Figure 7. Neurotoxic shellfish poisoning (NSP) in the

coastal United States, 1988-1998

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Return to Regional Contrasts
Harmful Algal Blooms - Figure 4

Figure 4.

Return to Figure 4-7 Index | Figure 4 | Figure 5 | Figure 6 | Figure 7

Return to Regional Contrasts

Figure 4. Ciguatera fish poisoning (CFP) in the coastal United States, 1988-1998

Source: National Office for Marine Biotoxins and Harmful Algal Blooms,

Woods Hole Oceanographic Institute; Turgeon et al. 1998.

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Return to Figure 4-7 Index | Figure 4 | Figure 5 | Figure 6 | Figure 7

Return to Regional Contrasts
Harmful Algal Blooms - Figure 5

Figure 5.

Return to Figure 4-7 Index | Figure 4 | Figure 5 | Figure 6 | Figure 7

Return to Regional Contrasts

Figure 5. Paralytic shellfish poisoning (PSP) in the coastal United States, 1988-1998

Source: National Office for Marine Biotoxins and Harmful Algal Blooms,

Woods Hole Oceanographic Institute; Turgeon et al. 1998.

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Return to Figure 4-7 Index | Figure 4 | Figure 5 | Figure 6 | Figure 7

Return to Regional Contrasts
Harmful Algal Blooms - Figure 6

Figure 6.

Return to Figure 4-7 Index | Figure 4 | Figure 5 | Figure 6 | Figure 7

Return to Regional Contrasts

Figure 6. Amnesic shellfish poisoning (ASP) in the coastal United States, 1988-1998

Source: National Office for Marine Biotoxins and Harmful Algal Blooms,

Woods Hole Oceanographic Institute; Turgeon et al. 1998.

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Return to Figure 4-7 Index | Figure 4 | Figure 5 | Figure 6 | Figure 7

Return to Regional Contrasts
Harmful Algal Blooms - Figure 7

Figure 7.

Return to Figure 4-7 Index | Figure 4 | Figure 5 | Figure 6 | Figure 7

Return to Regional Contrasts

Figure 7. Neurotoxic shellfish poisoning (NSP) in the coastal United States, 1988-1998

Source: National Office for Marine Biotoxins and Harmful Algal Blooms,

Woods Hole Oceanographic Institute; Turgeon et al. 1998.

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Return to Figure 4-7 Index | Figure 4 | Figure 5 | Figure 6 | Figure 7

Return to Regional Contrasts
Harmful Algal Blooms - Table 1

Return to Regional Contrasts

Table 1. HABs by species and coastal region

Coastal Geographic

Area

Documented HAB Problem Responsible HAB Species

 

Northeast (ME, NH,

MA, CT, NY)

PSP Alexandrium spp. 

Mid-Atlantic (NY,

NJ, RI, MA)

brown tide (reduced light penetration, severe

scallop mortalities, recruitment failure, growth

inhibition in scallops, adversely affects feeding of

bivalves)

Aureococcus anophagefferens

DE, MD, VA, NC,

SC, GA, FL

fish lesions Pfiesteria piscidaPfiesteria complex

Southeast and Gulf

of Mexico (TX, AL,

FL, SC, NC)

NSP Gymnodinium breve

Gulf of Mexico (TX) brown tide (see above for associated effects) Aureocoumbra lagune

Pacific Coast (CA,

OR)

PSP Alexandrium cantenella

ASP Pseudo-nitzschia australis

Pacific Coast (WA) PSP Alexandrium cantenella Alexandrium acatenella

Alexandrium tamarense

ASP Pseudo-nitzschia pungens P. australis P. pungens f.

multiseries Pseudo-nitzschia pseudodelicatissima

finfish mortalities Heterosigma carterae (akashiwo) Chaetoceros

concavicornis Chaetoceros convolutus

Pacific Coast (AK) PSP Alexandrium cantenella

Tropical (HI, FL,

Puerto Rico, US

Virgin Islands)

ciguatera fish poisoning Gamberdiscus toxicus

General to US

Coasts East

Coast/US (from FL

to ME)

cyanobacterial blooms (varying degrees of

toxicity in different organisms, negative aesthetic

values, odor and taste problems, anoxia, toxins)

Anabaena sp. Aphanizomenon sp. Microcystis sp. 

Southeast/US (FL as

well as many other

coastal areas of US)

macroalgae (seaweeds) (decreased seagrass

productivity, coral reef decline, hypoxic/anoxic

conditions)

red -Laurencia intricata, Spyridia filamentosa

brown - Dictyota sp., Sargassum filipendula

green -Enteromorpha sp. Colium isthmocladum

Halimeda sp. 

 

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