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Monitoring and Management Strategies for Harmful Algal Blooms in Coastal Waters

Front cover photographs:
Middle: Noctiluca bloom, Hai Ha Wan, Hong Kong. Photo by K. D. Wilson
Bottom: Fish kill following a high biomass Ceratium furca and Prorocentrum micans
bloom leading to oxygen depletion, South Africa. Photo by G. Pitcher.
Monitoring and Management Strategies for Harmful Algal
Blooms in Coastal Waters
Donald M. Anderson
Biology Department
Woods Hole Oceanographic Institution
Woods Hole MA 02543
Per Andersen
Bio/consult as
8230 Åbyhøj Denmark
V. Monica Bricelj
Institute of Marine Biosciences
National Research Council of Canada
Halifax NS Canada B3H 3Z1
John J. Cullen
Department of Oceanography
Dalhousie University
Halifax NS Canada B3H 4J1
J. E. Jack Rensel
Rensel Associates Aquatic Science Consultants
Arlington WA 98223
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 2
This report to be cited as:
Anderson, D.M., P. Andersen, V.M. Bricelj, J.J. Cullen, and J.E. Rensel. 2001. Monitoring and
Management Strategies for Harmful Algal Blooms in Coastal Waters, APEC #201-MR-01.1, Asia Pacific
Economic Program, Singapore, and Intergovernmental Oceanographic Commission Technical Series No.
59, Paris.
The designations employed and the presentations of the material in this publication do not imply the
expression of any opinion whatsoever on the part of the Secretariats of UNESCO and IOC concerning the
legal status of any country or territory, or its authorities, or concerning the delimitations of the frontiers of
any country or territory.
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 3
1.1 HAB Impacts 21
2.1 General issues 25
2.2 Basic elements 25
3.1 Methods of Toxin Analysis 29
3.1.1 General Considerations 29
3.1.2 Paralytic Shellfish Poisoning (PSP) Toxins 31 Emerging technologies. 35
3.1.3 Amnesic Shellfish Poisoning (ASP) Toxin 37
3.1.4 Diarrhetic Shellfish Poisoning (DSP) Toxins 39
3.1.5 Neurotoxic Shellfish Poisoning (NSP) Toxins 41
3.1.6 Other algal toxins 41
3.1.7 Ciguatera Fish Poisoning (CFP) Toxins 42
3.1.8 Toxin in Finfish and Consumption by Humans 45
3.2 Action or Regulatory Limits for Toxins and Cells 47
3.2.1 Shellfish 47
3.2.2 Finfish 52
3.3 Phytoplankton Cell Detection 54
3.3.1 Sampling of planktonic algae 54
3.3.2 Sampling of benthic microalgae 55
3.3.3 Fixation/preservation of algal samples 55
3.3.4 Labeling and storage 56
3.3.5 Volunteer plankton monitoring programs 56
3.3.6 New Cell Detection Methods 57 Antibodies 57 Nucelotide probes 58 Lectins 60 Application of molecular probes to natural populations 60 Use of molecular probes in new areas 61
3.3.7 Fish Indicators 62
3.4 Early Warning, Detection and Prediction of Blooms 63
3.4.1 Observing algal distributions in relation to environmental variability 64 Secchi disk 64 Chlorophyll a65 Fluorescence of chlorophyll in vivo 65 Spectral fluorescence excitation and emission in situ 66 Spectral attenuation and absorption 67
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 4 Ocean color 70 Flow cytometry 71
3.4.2 Characterizing Environmental Variability Relevant to Algal Blooms 72 Profiling systems 72 Underway sampling on ferries 73 Bio-optical moorings 74 Moored profiler 77
3.4.3 SEAWATCH™ system 77 Estimated costs and requirements for support 78 Monitoring algal blooms with SEAWATCHTM 78 Forecasting algal blooms with SEAWATCHTM 79 A general assessment of SEAWATCH for monitoring and predicting algal blooms
3.4.4 Observations from Aircraft 80 Visual detection of blooms 80 Quantitative observations of ocean color from aircraft 80 Imaging spectroradiometer 82 Satellite remote sensing 83 Remote sensing and forecasts of bloom dynamics 83 Remote sensing and research on algal blooms 83
3.4.5 Modeling 84
4.1 Fish Mariculture Monitoring 86
4.1.1 Norway 86
4.1.2 Pacific Northwest (North America) 91 Background and causative species 91 Chaetoceros subgroup Phaeoceros 93 Heterosigma akashiwo 94 Ceratium fusus 96 British Columbia (Canada) 97 Washington State (US) 98
4.1.3 Japan 99 Background and Causative Species 99
4.1.4 Chile 102 Background and causative species 102 Heterosigma akashiwo 102 Chilean fish farms and phytoplankton monitoring 104
4.2 Ciguatera 104
4.3 Shellfish Monitoring 105
4.3.1 United States 105 Atlantic US: State of Maine 105 Pacific US 113
4.3.2 Canada 118
4.3.3 Galicia, NW Spain 126
4.3.4 Denmark 132
4.3.5 New Zealand 137
4.3.6 France 149
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 5
4.3.7 Control of Imported and Exported Seafood Products 152 US: the NSSP/ISSC program 153 Canadian import program 155 The European Economic Community (EEC) 155
4.4 Monitoring for Pfiesteria-like Organisms 156
4.5 HAB Impacts on Beaches and Recreational Waters 157
4.5.1 Recreational use of beaches/coastal waters 157
4.5.2 Species toxic to humans through inhalation of sea spray, etc. 158
4.5.3 Species toxic to humans through dermal contact 159
4.5.4 Species toxic to animals (including humans) through oral intake while swimming
4.5.5 Non-toxic phytoplankton 160
4.5.6 Mitigation/precautionary measures 160
4.6 HAB Impacts on Ecosystems 162
4.7 Monitoring Program Costs 163
5.1 National/regional HAB Monitoring Programs 167
5.2 Public Education and Communication 168
6.1 Impact Prevention 174
6.1.1 Monitoring Programs 174
6.1.2 Nutrient Reductions 175
6.1.3 Ballast Water Introductions 177
6.1.4 Species Introductions via Mariculture Operations 178
6.1.5 Prediction 178 Models 178 Remote sensing 178
6.2 Bloom Control 179
6.2.1 Chemical Control 179
6.2.2 Flocculants (clays and long-chain polymers) 182
6.2.3 Physical Control 186 Skimming of Surface Water 186 Ultrasonic destruction of HAB cells 186
6.2.4 Biological Control 186 Grazing by zooplankton and suspension-feeding benthos. 186 Viruses 187 Parasites 188 Bacteria 189 Other algae 189
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 6
6.3 The Arguments Against Controlling HABs 190
6.4 In Situ Bloom Mitigation Methods for Fish Mariculture 191
6.4.1 Aeration 191
6.4.2 Oxygenation 198
6.4.3 Airlift Pumping 199
6.4.4 Moving Pens from Blooms 200
6.4.5 Perimeter Skirts 201
6.4.6 Ozone 203
6.4.7 Site Selection 204
6.4.8 Alternative Fish Culture Systems 205
6.4.9 Filter Systems 208
6.4.10 Dietary or Chemical Treatments 209
6.4.11 Miscellaneous Mitigation Practices 209
6.4.12 Survey of Mitigation Used Worldwide 210
6.5 Impact Prevention, Mitigation and Control Strategies – Shellfish 211
6.5.1 Species Selection 212
6.5.2 Detoxification 212
6.5.3 Tissue-Compartmentalization of Toxins (product selection) 217
6.5.4 Vertical Placement in the Water Column 217
6.5.5 Processing of Seafood 218
6.5.6 Detoxification by chemical agents 220
6.5.7 Biological control 220
6.6 Ciguatera Therapy 221
7.1 General Monitoring Issues 223
7.2 Finfish Mariculture and Monitoring 224
7.3 Finfish Mariculture: Mitigation of Fish Kills 225
7.4 Fish Mortality and Toxic Blooms 226
7.5 Effects of Harmful Algae on Shellfish 226
7.6 Biotoxins 227
7.7 Early Warning and Prediction 229
7.8 Control and Mitigation of Algal Blooms 231
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 7
FIGURE 1.1. Generalized pathways of human intoxication with molluscan shellfish toxins via filter-
feeding bivalves and carnivorous and scavenging gastropods. 24
FIGURE 2.1. Theoretical monitoring network for HABs. 26
FIGURE 3.1. Records of water transparency (i.e., Secchi depth, 5-year running mean) and the reported
frequency of blooms in the Seto Inland Sea, Japan, before and after the imposition of pollution controls in
1973. 65
FIGURE 3.2. Estimates of chlorophyll concentration based on measurements obtained with moored
spectral absorption meters in the southeast Bering Sea, 1993. 68
FIGURE 3.3. Detection of a dinoflagellate bloom with a radiometer buoy measuring ocean color, Aug. 18,
1993, during patchy discoloration of surface waters by high concentrations of the non-toxic dinoflagellate
Gonyaulax digitale. 70
FIGURE 3.4. Measurements of spectral diffuse attenuation coefficients [Kd(λ), m-1] in coastal waters off
Oregon (US). 71
FIGURE 3.5. Diffuse attenuation coefficient at 490 nm (Kd(490); m-1) in the upper 6 m, summer to fall
1997, Mahone Bay, Nova Scotia, Canada measured with a Tethered Attenuation Coefficient Chain Sensor.
FIGURE 3.6. The different origins of light received by a remote sensor pointed to the ocean surface. 81
FIGURE 4.1. Sources of information in the Norwegian HAB monitoring program. 87
FIGURE 4.2. Scenario showing how information about HAB situations is collected, evaluated and
communicated to fish farmers and insurance companies in Norway. 90
FIGURE 4.3. Information collection and distribution system for red tide/HAB information in the Seto
Inland Sea, Japan. 101
FIGURE 4.4. Information exchange and red HAB investigations in the Seto Inland Sea, Japan. 101
FIGURE 4.5. Sources of shellfish for routine biotoxin monitoring. 106
FIGURE 4.6. Structure and responsibilities for the shellfish biotoxin monitoring program in the State of
Maine (ME), Atlantic US. 108
FIGURE 4.7. Distribution of primary sampling stations for shellfish biotoxin monitoring within 18 coastal
regions in Maine, Atlantic, US. 110
FIGURE 4.8. Action plan for the shellfish monitoring program in the State of Maine, Atlantic, US. 112
FIGURE 4.9. Regions on the Atlantic coast of Canada in which PSP, ASP and DSP toxins have been
identified in molluscan shellfish. 119
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 8
FIGURE 4.10. Temporal changes in the phytoplankton and shellfish toxin monitoring programs in the
Maritimes, Atlantic Canada (New Brunswick, Prince Edward Island and eastern Nova Scotia), 1987/88-
1997. 124
FIGURE 4.11. Predictive relationships established from HAB monitoring data from the Gulf of St.
Lawrence region, Quebec, Canada (1986 to 1994). 127
FIGURE 4.12. Location of sampling sites in Galicia, Spain. 130
FIGURE 4.13. Action plan for the biotoxin monitoring program in Galicia, NW Spain. 131
FIGURE 4.14. Areas of the Danish coastal waters and fjords where monitoring of harmful algae and algal
toxins in mussels is conducted. 133
FIGURE 4.15. Flow of communication through the Danish monitoring program for toxic algae and algal
toxins in mussels. 137
FIGURE 4.16. Map showing the many different toxic or potentially harmful phytoplankton species in
New Zealand waters. 139
FIGURE 4.17. Network used for shellfish poisoning monitoring in French coastal waters. 150
FIGURE 4.18. Location of IFREMER laboratories and REPHY sampling stations. 152
FIGURE 4.19. Cost of the harmful algae monitoring program in Galicia, NW Spain within the context of
overall environmental quality monitoring. 165
FIGURE 5.1. Worldwide status of HAB monitoring programs in 1966. 167
FIGURE 5.2. Organization of red tide/HAB monitoring in the Philippines. 169
FIGURE 5.3. A Danish brochure presenting information on the risk of collecting and eating shellfish in
relation to algal toxins. 171
FIGURE 5.4. Danish information material for the public about the risk of swimming during algal
blooms/red tides. 172
FIGURE 5.5. Philippine poster informing the public about safe handling of seafood, and which seafoods
are safe to eat during a red tide. 173
FIGURE 6.1. Electrical powered regenerative blower (left) and diffused airstone (right). 193
FIGURE 6.2. Typical pond application of a propeller-driven, electrically powered air aspiration system.
FIGURE 6.3. Underwater view of a propeller-driven, electrically powered air aspiration system, showing
the hollow tube and prop wash from the propeller. 194
FIGURE 6.4. Schematic diagram of a venturi nozzle system using pumped seawater from any source and
a rigid airline to allow suction of air. 195
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 9
FIGURE 6.5. A series of Ocean Spar pens showing the corner spars and supporting anchoring structures.
FIGURE 6.6. Upper: Maximum PSP toxicities historically recorded in field-toxified North American
bivalves. Lower: Toxicity maxima in molluscan shellfish from southern China, Guangdong, recorded in
1990-1992. 213
FIGURE 6.7. Flow chart of steps involved in chemical detoxification of mussels contaminated with PSP
toxins and resulting decrease in toxicity. 221
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 10
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 11
TABLE 1.1 Human illnesses associated with harmful algal blooms. 23
TABLE 2.1. Examples of environmental parameters that could be included in a HAB monitoring program.
TABLE 3.1. A comparison of whole animal and in vitro assay techniques, and the high performance liquid
chromatography – fluorescence detection (HPLC-FD) method, for PSP toxin determination in shellfish
samples. 33
TABLE 3.2. Categorization of phytoplankton toxins according to their cellular targets and identified toxin.
TABLE 3.3. Examples of specific HAB species, associated toxin or chemical, category of toxins, and
organ or tissue in fish primarily targeted by that toxin. 46
TABLE 3.4. ASP toxin detection methods and action limits. 47
TABLE 3.5. DSP toxin detection methods and action limits. 48
TABLE 3.6. PSP toxin detection methods and action limits. 49
TABLE 3.7. Cell concentrations of HAB species that result in implementation of restrictions on
shellfisheries. 50
TABLE 3.8. Harmful phytoplankton species known or suspected of causing fish losses in mariculture,
recommended action concentrations and a few pertinent references. 52
TABLE 3.9. Antibody probes developed for HAB species. 58
TABLE 3.10. Compact profiling systems. 73
TABLE 4.1. Harmful algae of concern to Norwegian fish and shellfish industries. 87
TABLE 4.2. Norwegian guidelines to fish farmers. 89
TABLE 4.3. Fish-killing phytoplankton species known to be present in Puget Sound, Washington State,
US. 92
TABLE 4.4. HAB species known to cause mass fish mortalities in Japanese coastal waters. 100
TABLE 4.5. Fish-killing phytoplankton species known to be present in coastal waters of Chile. 103
TABLE 4.6. A chronology of events for the 1987 ASP/domoic acid crisis in Atlantic Canada. 121
TABLE 4.7. Summary of guidelines for monitoring algal toxins in the Danish mussel-fisheries. 135
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 12
TABLE 4.8. Toxic and potentially toxic algae reported from Danish waters. 135
TABLE 4.9. Recommended action limits for toxic and potentially toxic algae in relation to the Danish
mussel fisheries. 136
TABLE 4.10. Conditions required for determination of safe consumption of non-commercial shellfish in
New Zealand. 143
TABLE 4.11. Methods used for HAB toxin detection in New Zealand. 145
TABLE 4.12. Number of shellfish samples tested for toxicity in New Zealand for 1999-2000. 146
TABLE 4.13. New Zealand National Marine Biotoxin Plan – phytoplankton action levels. 147
TABLE 4.14. Toxic and potential toxic algae recorded in French waters. 150
TABLE 4.15. Methods used for detection of algal toxins as well as the action limits of toxins and the
resulting action. 151
TABLE 4.16. Summary of toxic phytoplankton species involved in human intoxications through
inhalation or direct contact. 158
TABLE 4.17. Diatoms and dinoflagellates responsible for HABs on the upper Adriatic coast. 162
TABLE 4.18. Approximate annual production value for finfish (F) and shellfish (S) versus the
approximate cost of monitoring HABs (in US$). 164
TABLE 4.19. Estimated annual cost of PSP, DSP and CFP outbreaks in Canada, broken into societal,
private and industry-related. 166
TABLE 6.1. Evaluation of the clay flocculation method by Japanese fishermen during a Cochlodinium
bloom. 184
TABLE 6.2. Comparison of diffuser air systems estimated capital costs versus venturi nozzle systems,
assuming depth of placement at 2 m. 197
TABLE 6.3. Hypothetical example of oxygen supersaturation as a method for harmful microalgal bloom
mitigation for salmon net-pen systems. 199
TABLE 6.4. Summary of mitigation measures used in fish mariculture facilities. 211
TABLE 6.5. Detoxification of PSP toxins by bivalve molluscs (adults unless indicated), as measured by
the time required to attain the regulatory level 214
TABLE 6.6. Detoxification of domoic acid in bivalve molluscs (whole tissues unless specified). 216
TABLE 6.7. Detoxification rate of DSP toxins from bivalve molluscs (viscera). 216
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 13
TABLE 6.8. Annex to the Commission Decision 97/77/EC of 18 January 1996, published in the Official
Journal of the European Communities of January 20 1996. 219
TABLE 7.1. Summary of HAB monitoring and management technologies. 232
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 14
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 15
ADEC Alaska Department of Environmental Conservation
AFCD Agriculture and Fisheries Conservation Department (Hong Kong)
AOAC Association of Official Analytical Chemists
APEC Asia Pacific Economic Cooperation Program
APHA American Public Health Association
ASP amnesic shellfish poisoning
ATS Aquaculture Technology Section
AVIRIS Airborne Visible/Infrared Imaging Spectrometer
AZA azaspiracid
AZP azaspiracid shellfish poisoning
CDOM colored dissolved organic matter
CEC Commission of European Communities
CFIA Canadian Food Inspection Agency
CFP ciguatera fish poisoning
COIS Coastal Ocean Imaging Spectrometer
CSSP Canadian Shellfish Sanitation Program
CTD conductivity, temperature, depth
CTX ciguatoxin
CV coefficient of variation
CWC Chemical Weapons Convention
CZCS Coastal Zone Color Scanner
DA domoic acid
DEC Department of Environmental Conservation (Alaska, US)
DFO Department of Fisheries and Oceans (Canada)
DMR Department of Marine Resources (Maine, US)
DO dissolved oxygen
DOC dissolved organic carbon
DON dissolved organic nitrogen
DOP dissolved organic phosphorus
DSP diarrhetic shellfish poisoning
DTX dinophysistoxin
ELISA enzyme-linked immunosorbent assay
EC Environment Canada
ECOHAB Ecology and Oceanography of Harmful Algal Blooms (US)
EEC European Economic Community
EPA Environmental Protection Agency (US)
EU European Union
FAQ frequently asked questions
FCZ fish culture zone
FDA Food and Drug Administration (US)
FISH fluorescent in situ hybridization
GEOHAB Global Ecology and Oceanography of Harmful Algal Blooms
GIS geographic information system
GOOS Coastal Global Ocean Observing System
GTX gonyautoxin
HAB harmful algal bloom
HACCP Hazard Analysis Critical Point Control Program (US)
HFS hydrodynamic filtration system
HMA heteroduplex mobility assay
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 16
HPLC high performance liquid chromatography
IANZ International Accreditation New Zealand
IFREMER Institut Français pour la Recherche et l’Exploitation de la Mer
IMO International Maritime Organization
IOC International Oceanographic Commission
ISSC Interstate Shellfish Sanitation Conference (US)
IUPAC International Union for Pure and Applied Chemistry
LBA light-beam attenuation
LC liquid chromatography
LDPE low-density polyethylene
MAb monoclonal antibody
MAF Ministry of Agriculture and Forestry (New Zealand)
MBMB Marine Biotoxin Management Board (New Zealand)
MoH Ministry of Health (New Zealand)
MOU Memorandum of Understanding
MS mass spectrometry
MU mouse units
NEO neosaxitoxin
NERI National Environmental Research Institute (Denmark)
NMFS National Marine Fisheries Service (US)
NRC National Research Council (Canada)
NSP neurotoxic shellfish poisoning
NSSP National Shellfish Sanitation Program (US)
OA okadaic acid
OBS optical backscatter
ORHAB Olympic Region Harmful Algal Blooms
PAb polyclonal antibody
PAC polyhydroxy aluminum chloride
PbTx brevetoxin
PCR polymerase chain reaction
PIC Panchromatic Imaging Camera
PSP paralytic shellfish poisoning
PUFA polyunsaturated fatty acid
PTX pectenotoxin
QMPI Quality Management Program for Importers (Canada)
REOS Remote Electro-Optical Sensor
REPHY French Phytoplankton Monitoring Network
RIA radioimmunoassay
RL regulatory level
RT red tide
RT/HAB red tide/HAB
SAX strong anion exchange
SCOR The Scientific Committee on Oceanic Research
SDE sediment oxygen demand
SeaWIFS Sea-viewing Wide Field-of-view Sensor
SPIA solid phase immunobed assay
SQAPDC Shellfish Quality Assurance Program Delivery Center (New Zealand)
SST sea surface temperature
STX saxitoxin
TOC total organic carbon
TSP toxic shellfish poisoning
UK United Kingdom
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 17
US United States
WHO World Health Organization
WWW World Wide Web
YTX yessotoxin
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 18
The authors wish to acknowledge and thank the many individuals and agencies who assisted in the
compilation of information and in the preparation of this report. In particular, we thank the Agriculture
and Fisheries Conservation Department (AFCD) of the Hong Kong Special Administrative Region (SAR)
government for allowing us to modify a report prepared for them and to publish it for general distribution,
as well as members of the AFCD staff who assisted in the preparation of that report and others. This
includes Man-kwong Cheung, Patsy Wong, Jim Chu, and Minna Wong. Many other members of the
Study Management Group were also of great assistance.
The following individuals provided information, and in some cases, contributed graphics to this report: in
Canada, D. Richard (CFIA, Moncton, NB), J. Martin (DFO, St. Andrews, NB), S. Hancock (CFIA,
Dartmouth), M. Levasseur and D. Blasco (Maurice-Lamontagne Institute, DFO, Quebec), G. Sauvé
(CFIA, Quebec), S. Bates (DFO, Moncton, NB), M. Laycock (IMB, NRC), and especially M. Quilliam
(IMB, NRC, Halifax, NS), who shared literature sources, contributed to valuable discussions and reviewed
an early draft of sec. 3.1; L. Bean, J. Hurst, P. Anderson (State of Maine Department of Marine Resources,
USA), S. Shumway (Long Island University, New York, USA), S. Hall (US FDA), B. Reguera, (Instituto
Español de Oceanografía, Vigo, Spain), J. Blanco (Centro de Investigaciones Marinas, Vilanova de
Arousa, Spain) and J. Maneiro (Centro de Control de Calidade do Medio Mariño, Vilagarcía de Arousa,
Spain), Helen Smale (Marlborough Shellfish Quality Assurance Program, New Zealand), Kirsten Todd
(Cawthron Institute, New Zealand), and J. Ebesu of Oceanit Test Systems, Inc. We especially
acknowledge Catherine Seamer, Technical Advisor of the MAF Food Assurance Authority, Wellington,
New Zealand, for her invaluable help and contributed text on the current New Zealand monitoring
program (sec. 4.3.5.) and P. Busby (MAF Regulatory Authority) for providing access to this information.
Steve MacKenna and Scott MacQuarrie (IMB, NRC) assisted with graphics preparation.
Thanks also to J. Forster (Forster Consulting, Inc., Port Angeles WA), B. Hicks, (International
Aquafoods), G. Robinson (Stolt Sea Farm), Ian Whyte (Fisheries and Oceans, Canada), A. Clement
(INTESAL, Puerto Montt, Chile), F.H. Chang (National Institute of Water and Atmospheric Research
Ltd., New Zealand), T. Thorsen (Vesta Insurance, Norway), J. Morris (Roberts Morris Bray Insurance
Brokers, London), G. Smart (Culmarex, Spain, Y. Karakassis, (Greece), N. Hopkins, (SBJ Nielson
Steavenson Ltd., London), R. Murell (Brouwer Claims, Canada), A. Bringsvor (Hydro Seafood, Norway),
B. Smith (Bruce Smith and Associates, Scotland), M. Beveridge (University of Stirling, Scotland), J.
Halstead (Research Nets Inc., Bothell, Washington), S. Christensen (Christensen Net Works, Ferndale,
Washington), and R. Lewis (University of Queensland, Australia).
Special thanks also to Dr. John Hodgkiss and the administrative staff at the Department of Ecology and
Biodiversity, Hong Kong University who provided expert graphic and clerical support, including Leo
Chan, Flora Chan and Eva Tam. We are also extraordinarily grateful to Judy Kleindinst (Woods Hole
Oceanographic Institution) for her assistance on all aspects of this effort, especially for her hard and
tedious work collating changes and additions from the multiple authors involved in both versions of this
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 19
In early 1998, a toxic red tide devastated the fish farming industry in Hong Kong. In response to the
attention given to this event by the general public and the fisheries industry, the government
commissioned a study of the existing red tide monitoring management program in Hong Kong, which
included recommendations on ways to update and change it. One element of that study involved a
compilation of existing monitoring, management, and mitigation technologies used on red tides and
harmful algal blooms throughout the world. The resulting report: Technical Report No. 2: Red Tide
Monitoring and Management Strategies (Anderson et al., 1999) was only available to officials within the
Hong Kong government. The authors felt that the information that had been compiled would be of interest
and use to many others faced with harmful algal bloom problems globally. Accordingly, upon the authors’
request, the Hong Kong Agriculture and Fisheries Conservation Department kindly granted permission to
publish an edited version of this report. Specific references to Hong Kong were removed at the AFCD’s
request to make the report more useful globally. The editing and printing of the report were facilitated by
the Project on Management of Red Tides and Harmful Algal Blooms of the Asia Pacific Economic
Cooperation Program (APEC) Marine Resource Conservation Working Group. The distribution and
mailing of the edited report outside of the APEC region was supported by the Harmful Algal Bloom
Program of the Intergovernmental Oceanographic Commission (IOC) of UNESCO.
Several issues should be noted with respect to the information compiled in this report. These relate mostly
to rapid changes in technology and policy as well as the occurrence of new toxic events since the report
was initially written in early 1999. First, prices for the various instruments described here are estimates
made in 1999 and many new products or pricings are not listed. It was simply not possible to update many
of the figures and product descriptions in this edited report given the limited resources available for the
editing and publication process. Second, web site addresses are provided throughout the text, though the
addresses or sites are expected to change or to become inactive through time. Readers are encouraged to
use an appropriate search engine to find equivalent sites if the addresses given here are no longer valid.
Third, species names have not been changed to reflect a very recent publication (Daugbjerg et al., 2000)
that proposed sweeping changes to the genera Gymnodinium and Gyrodinium. Finally, we emphasize that
although this is an extensive compilation of monitoring and management methods, it is far from complete
or even up-to-date. Specific national monitoring programs were selected as case studies, but many
countries with excellent programs are not included. We apologize to individuals, companies, programs or
countries who are not mentioned or whose recent studies, results, or policy changes are not included. We
hope all realize that our objective is to provide a broad but necessarily incomplete overview of the many
different technologies, methods and approaches that were being used in early 1999 to monitor and manage
HABs in coastal waters worldwide.
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 20
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 21
The world’s oceans teem with countless single-celled algae called phytoplankton. Among the thousands of
living species are a few dozen that produce potent neurotoxins or that cause harm in other ways. Impacts
from “blooms” or “red tides” of these tiny organisms are many and diverse, ranging from the death or
illness of humans, whales, manatees, or other marine animals to discoloration of the water and fouling of
beaches with foam and dead fish. Ecosystem effects also occur, as toxins are transferred through the food
chain, affecting larval as well as adult forms of many marine organisms.
In some areas the term “red tide” is used to describe all phenomena in which the water is discolored by
high algal biomass. This term is potentially misleading, however, because it includes many blooms which
discolor the water but cause no harm, and ignores blooms of highly toxic cells, which cause problems at
very low (and essentially invisible), cell densities. As a result, many bloom events which are harmless end
up having negative impacts because skittish consumers avoid purchasing or eating seafood which is
perfectly safe, or tourists and residents avoid using beaches because of a mistaken concern over swimming
safety. Because of this confusion, the term harmful algal bloom (HAB) is now used by scientists and
government officials in most countries to describe the subset of these phenomena which are toxic or cause
harm. In this report, the term “harmful algal bloom” or HAB will be used in its most general or
inclusive sense – it will refer to blooms of toxic and non-toxic algae which discolor the water, as well
as to blooms which are not sufficiently dense to change water color but which are dangerous because
of the algal toxins they contain or the physical damage they cause to other biota. We do recommend
that an effort be made to alter the usage of “red tide” in those countries that still use this term. It should be
possible to decrease negative impacts by ensuring that negative public reactions are confined to only those
events that are toxic or potentially harmful.
HABs are truly global phenomena, and evidence is mounting that the nature and extent of the problem has
been expanding over the last several decades (Anderson 1989; Smayda 1989). Formerly only a few
regions were affected in scattered locations, but now virtually every coastal country is threatened, in many
cases over large geographic areas and by more than one harmful or toxic species. It is still a matter of
debate as to the causes behind this expansion, with possible explanations ranging from natural mechanisms
of species dispersal to a host of human-related activities such as nutrient enrichment, climatic shifts, or
transport of algal species via ship ballast water. Whatever the reasons, we are now subject to a bewildering
array of toxic or harmful species and impacts, and are faced with disturbing trends of increasing incidence
throughout the world.
Given this significant problem and an increasing reliance on the coastal zone for habitation, food,
recreation, commerce, and even waste disposal, how can we achieve the balance between these needs and
the effect they may have on nearshore waters, and in particular, on coastal ecosystems? What actions are
necessary to manage resources affected by HABs, and what research is needed to provide the scientific
basis for policy decisions? Perhaps most importantly, can anything be done to reverse the trend in bloom
incidence – will improvements in coastal water quality lead to fewer or smaller blooms of toxic species or
can strategies be employed to directly intervene in the bloom process, to destroy the bloom organisms?
These are important questions, made all the more compelling by the expansion of the problem through
1.1 HAB Impacts
HAB phenomena take a variety of forms and have multiple impacts. One major category of impact occurs
when toxic phytoplankton are filtered from the water as food by shellfish such as clams, mussels, oysters,
or scallops, which pump large volumes of water and hence can rapidly accumulate the algal toxins to
Monitoring and Management Strategies forHarmful Algal Blooms in Coastal Waters 22
levels which can be lethal to humans or other consumers (reviewed in Shumway 1990). These poisoning
syndromes have been given the names paralytic, diarrhetic, neurotoxic, amnesic and azaspiracid shellfish
poisoning (PSP, DSP, NSP, ASP and AZP respectively; Table 1.1). Carnivorous gastropods (snails,
whelks), either predatory species (e.g. Nassarius succinctus and Babylonia areolata) which consume live
bivalve prey, or scavengers which consume dead bivalve prey, can also act as important vectors of PSP
toxins (Shumway et al. 1995). For example, the large snail, N. succinctus, is a popular food item in some
Asian countries, and has been frequently implicated as a vector of PSP in mainland China (Chen and Gu
1993, Qiu 1990 in Lin et al. 1993). These two main vectors for the food web transfer of PSP toxins to
humans are illustrated in Fig. 1.1. A sixth human illness, ciguatera fish poisoning (CFP) is caused by
biotoxins produced by dinoflagellates attached to surfaces in many coral reef communities (reviewed in
Anderson and Lobel 1987). Ciguatera toxins are transferred through the food chain from herbivorous reef
fishes to larger carnivorous, commercially valuable finfish. In a similar manner, the viscera of other
important fish such as herring or sardines can contain PSP toxins, endangering human health following
consumption of whole fish. Whales, dolphins, seabirds, and other animals can be victims as well, receiving
toxins through the food chain via contaminated zooplankton or fish (e.g., Geraci et al. 1989).
Another type of HAB impact occurs when marine fauna are killed by algal species that produce exogenous
toxins associated with the cell surface, release toxins and other compounds into the water, or that kill
without toxins by physically damaging gills, by creating low oxygen conditions as bloom biomass decays
or by causing light attenuation as thus affecting submerged aquatic vegetation. Some algae (including but
not restricted to those that produce chemically well-characterized toxins known to affect humans), can
adversely affect growth and survival of larvae or adults of commercially important shellfish populations.
For example, red tides of the dinoflagellate Heterocapsa circularisquama in Japan are not a public health
concern and do not appear to affect finfish, but have caused mass mortalities of valuable cultured pearl
oysters (Pinctada fucata) as well as edible bivalves including Pacific oysters (Crassostrea gigas ), clams
(Tapes philippinarum) and mussels (Mytilus galloprovincialis) (Matsuyama et al. 1996). Similarly, brown
tides of the picoplanktonic alga Aureococcus anophagefferens (Pelagophycea) have caused mass
mortalities (not linked to hypoxia) of mussels, and devastated bay scallop fisheries in the mid-Atlantic
USA, but are not known to affect finfish or humans (Bricelj and Lonsdale 1997). Finally, some algal
toxins that are of human health concern also have direct negative effects on shellfish populations. For
example, PSP toxins produced by Alexandrium spp. also were shown in laboratory studies to cause
burrowing and feeding incapacitation, and even mortalities of softshell clams, Mya arenaria (MacQuarrie
and Bricelj 2000). Farmed fish mortalities from HABs have increased considerably in recent years, and are
now a major concern to fish farmers and their insurance companies. The list of finfish, shellfish and
wildlife affected by algal toxins is long and diverse (Anderson 1995) and accentuates the magnitude and
complexity of the red tide phenomena. In some ways, however, this list does not adequately document the
scale of red tide effects, as adverse impacts can occur throughout coastal ecosystems in subtle ways that
are difficult to detect. In virtually all trophic compartments of the marine food web, there can be impacts
from toxic or harmful blooms.
Finally, economic impacts can also result from the so-called “halo effect”, or avoidance of safe,
uncontaminated seafood because of mistaken public perceptions that the red tide has affected all fish and
shellfish and that toxins that kill these organisms are retained within their tissues. Management strategies
must address this public overreaction and devise strategies (e.g. via public education) to reduce these
TABLE 1.1 Human illnesses associated with harmful algal blooms. (Modified from Morris 1999.)
Syndrome Causative organisms Toxins produced Route of acquisition Clinical manifestations
Ciguatera fish
poisoning (CFP)
Gambierdiscus toxicus
(benthic) and others
Ciguatoxins Toxin transfer up the
marine food chain;
illness generally results
from eating large,
carnivorous reef fish
Acute gastroenteritis, paresthesias and
other neurological symptoms
poisoning (PSP)
Alexandrium spp,
catenatum, Pyrodinium
bahamense var.
compressum and others
Saxitoxin family Eating shellfish
harvested from affected
Acute paresthesias and other neurological
manifestations; may progress rapidly to
respiratory distress, muscular paralysis
and death
poisoning (NSP)
Gymnodinium breve,
G. brevisulcatum and
Brevetoxins Eating shellfish
harvested from affected
areas; toxins may be
aerosolized by wave
Gastrointestinal and neurological
symptoms; respiratory and eye irritation
with aerosols
poisoning (DSP)
Dinophysis spp. Okadaic acid and
Eating shellfish
harvested from affected
Acute gastroenteritis
poisoning (AZP)
Azaspiracids Eating shellfish
harvested from affected
Neurotoxic effects with severe damage to
the intestine, spleen, and liver tissues in
animal tests
poisoning (ASP)
Pseudo-nitzchia spp. Domoic acid and
Eating shellfish (or,
possibly, fish)
harvested from affected
Gastroenteritis, neurological
manifestations, leading in severe cases to
amnesia (permanent short-term memory
loss), coma, and death
Possible estuary-
Pfiesteria piscicida and
other Pfiesteria spp.
Unidentified Exposure to water or
aerosols containing
Deficiencies in learning and memory;
acute respiratory and eye irritation, acute
confusional syndrome
Monitoring and Management Strategies for Harmful Algal Blooms in Coastal Waters 24
FIGURE 1.1. Generalized pathways of human intoxication with molluscan shellfish toxins via filter-
feeding bivalves and carnivorous and scavenging gastropods. (Modified from Shumway et al. 1995.)
Toxic Dinoflagellates
(eg. Alexandrium sp.)
Carnivorous & scavenging
Filter - feeding bivalve mollusks
(clams, scallops, etc.)
Human death
and/or illness
Nassarius sp.
Euspira sp.
Busycon sp.
Monitoring and Management Strategies for Harmful Algal Blooms in Coastal Waters 25
2.1 General issues
The goal of all HAB research and monitoring efforts is to protect public health, fisheries resources,
ecosystem structure and function, and coastal aesthetics. This requires an understanding of the many
factors that regulate the dynamics of HABs and the manner in which they cause harm, but by itself, that
knowledge does not provide protection. Management and mitigation strategies of many different types are
needed. An effective management system for HABs therefore must have a variety of elements. At the core
of those programs are the monitoring programs needed to detect cells or toxins sufficiently early to take
management actions. Those management actions should be clearly defined for each of the many different
types of HAB impacts (e.g., shellfish toxicity, fish mortalities).
The following section provides background on basic or generic components of HAB monitoring programs.
More detail will be provided in Section 4 in the form of case studies highlighting specific programs in a
number of different countries.
The design elements of HAB monitoring programs must reflect the goals of those programs, the facilities
and resources available, and the specific demands of the end-users of the data, as well as the rules and
regulations imposed by the responsible national or regional authorities. Monitoring programs must be
adapted to local conditions and circumstances, and wherever possible, should be interfaced with other
monitoring efforts, such as those for general water quality, taking into account the physical and biological
regime, available technology, expertise and competence of the staff to carry out the monitoring and
management procedure, as well as local administrative tradition (Andersen 1996).
2.2 Basic elements
The basic or generic elements of a HAB monitoring program (Figure 2.1) are:
Environmental observations including plankton observations, fish kills and anomalous animal
Sampling of plankton, shellfish or fish
Analysis of the samples (identification of harmful algae, quantification of harmful algae, measuring
toxicity in shellfish or fish)
Evaluation of results
Dissemination of information and implementation of regulatory action
Action plans /Mitigation measures
The structure of a monitoring program can be complex depending upon the number of institutions
involved in the procedures at each level in the network. Some involve a single agency that collects the
samples and analyzes them for toxins. Others split the responsibilities, sometimes with private industry or
user groups. For example, in Denmark the sampling of algae and mussels is carried out by the fishermen,
but the analysis of those samples is conducted by private consultancy companies. Those companies report
to the Ministry of Fisheries, which is ultimately responsible for management decisions.
The structure of the HAB monitoring program must be kept as simple as possible to facilitate fast and
uncomplicated flow of information. It must be clear to everyone involved who is responsible for the
different parts of the program. The operational structure should be well documented in the form of a report
distributed to all users, containing information on which institutions are involved, the responsible persons
in the different institutions (addresses, phone and fax numbers, e-mail addresses etc.) and a clear
Monitoring and Management Strategies for Harmful Algal Blooms in Coastal Waters 26
description of the tasks for which each institution/person is responsible. It is also useful to have flow
charts or action plans outlining the steps to be taken in different circumstances, such as a human poisoning
or fish mortality episode, the detection of high levels of a known toxin, or the identification of a new toxin.
In preparing these plans, it is useful to assume that the individual faced with management decision has
little or no prior experience with HABs or their toxins. This helps to insure that a suitable level of detail is
provided in the written documentation. Some examples of action plans developed by individual countries
and regions are presented in Section 4.
FIGURE 2.1. Theoretical monitoring network for HABs. (Source: Andersen 1996.)
Monitoring marine environmental conditions in relation to red tides/HABs can be carried out at different
levels of detail, that is with different levels of temporal and geographical as well as vertical and horizontal
resolution, depending upon which kind of HAB is to be monitored. Furthermore, depending upon the goal
of the monitoring program, it can include a range of environmental parameters (Table 2.1). This list is
meant only as a general guideline. Specific programs may find that only a subset of these parameters is
appropriate for the goal of the program. Others may add many other parameters to the list.
Monitoring and Management Strategies for Harmful Algal Blooms in Coastal Waters 27
TABLE 2.1. Examples of environmental parameters that could be included in a HAB monitoring
Physical Chemical Biological
Wind speed and direction
Light attenuation/turbidity
- Nitrogen
- Phosphorous
- Silicate
- Toxic species
- Other species
Data acquisition. When monitoring data are collected in the field, it is important that the staff responsible
for sampling have detailed guidance on what and how to sample. The information should be available in
an official manual that defines:
which kinds of samples should be collected and analyzed
which forms are to be used
the methods used for sampling, the analyses to be performed, and units used
the institution/individual responsible for collecting the samples
the institution/individual responsible for working up the samples
how the data are to be archived and analyzed.
Preprinted forms should be filled in with the monitoring data as well as additional information on the
sampling, such as location/position, station name/number, and identification code for the staff responsible
for sampling. An example of a well-designed manual is that of the National Marine Biotoxin Program of
New Zealand, discussed further in Section 4.3.5. The manual is set up so that pages are easily removed
and replaced with updated versions without compromising the flow or utility of the program. Material in
the manual includes details of the administration of the national plan, methodological details, harvesting
closure and re-opening procedures, methods for investigating toxic shellfish poisoning cases, product
control, as well as a range of appendices with definitions, forms, and other details. Once the results of the
different analyses are available, it is important to create well-defined routes for communication. In
addition to providing information during actual outbreaks, monitoring data can be used to provide
forecasts which define risk-zones in time and space, such as areas with a high incidence of toxic outbreaks,
or conversely, areas where HABs are rare. Site selection of aquaculture facilities often requires careful
analysis of long term monitoring data to identify sites which have a low risk of HAB damage. It is often
the case that the personal experience of individuals who have been directly involved in the analysis of
HAB data over many years allows those individuals to make forecasts or predictions of trends in HAB
incidence or transport. These individuals are extremely valuable to monitoring programs, and every effort
should be made to keep them involved in program activities. Though non-quantitative, this type of
experience-based analysis is often quite accurate for predictive purposes and for guiding management
Distribution of information to users.
It must be clearly defined which institution/person is responsible for compilation/synthesis of the
monitoring results, and how the results of the analyses are to be presented to the public and users of the
program. A single spokesperson or communications node is desirable to avoid conflicting reports from
Monitoring and Management Strategies for Harmful Algal Blooms in Coastal Waters 28
multiple government agencies or organizations. Results can be distributed instantly to the users of the
monitoring system by telephone, telephone answering machine, fax, e-mail and Internet. The use of the
Internet to distribute HAB monitoring data is common in many countries/regions, though in some cases,
restricted access web sites or listservers available only to government officials are used to control the
release of sensitive information. Data on toxicity of shellfish, for example, is often highly sensitive with
major economic implications, and it may, therefore, be prudent to keep such results private, making sure,
however, that appropriate and acceptable management actions are taken. The following WWW pages
provide examples of how monitoring information is presented in this manner:
The Baltic Sea Algaline WWW-page:
This page contains information on the quantitative occurrence of phytoplankton in general, including
HAB species in the Baltic Sea.
The Baltic WWW-page:
This page focuses on HABs in the coastal areas of the Baltic Sea.
The Irish HAB WWW-page:
This page focuses on HABs as they affect Irish shellfisheries and contains general information on
HABs as well as practical instructions (e.g. how to sample phytoplankton for HAB analysis). More
detailed information on the current situation on algal toxins and toxic algae in relation to the Irish
shellfisheries is available for persons with an appropriate password, which is granted on request.
The Norwegian HAB WWW-page:
This page focuses on the occurrence of toxic algae and algal toxins in shellfish in Norwegian coastal
areas. The users of the information are the recreational shellfishermen, commercial mussel culturists,
and the Norwegian mariculture industry.
The Korean HAB WWW-page:
This page focuses on distribution of HAB information to aquaculturists, fishermen and the municipal
administrative authorities.
Monitoring and Management Strategies for Harmful Algal Blooms in Coastal Waters 29
3.1 Methods of Toxin Analysis
3.1.1 General Considerations
The section below focuses primarily on methods currently used in routine toxin monitoring. However,
some of the most promising emerging technologies, which may offer alternative methods in the near
future, are also described. Chapters on algal biotoxin assays in the IOC Manual on Harmful Marine Algae
(Cembella et al 1995; Wright and Quilliam 1995 in Hallegraeff et al. 1995) and a recent report (Cembella
1998) provide the main sources for this summary. The IOC manual is presently out of print, but is
available on the web at: A second edition of
the manual is in preparation at this time, and should be available in 2002.
Monitoring of algal toxins involves assays and/or analytical or instrumental methodologies. Assay
methods yield a single quantitative value representative of the overall toxicity or toxin content of the
sample. They include in vivo bioassays using live animals (e.g. the Association of Official Analytical
Chemists, AOAC, mouse bioassay) or in vitro assays, including:
Cytotoxicity assays (these can eliminate the need for live animals by using immortal cell lines);
Receptor assays (in which binding affinity of a toxin is related to its potency);
Immunological or structural assays;
Analytical methods are often used by regulatory agencies for confirmatory analysis of toxin components,
and in some cases as certified methods in routine monitoring, e.g. high-performance liquid
chromatography (HPLC) is the approved method for analysis of domoic acid worldwide. These methods
usually cannot be used for rapid screening, require costly equipment, and are carried out in centralized
laboratories with highly trained personnel. Most countries, with the exception of two European countries,
still rely on the use of mouse bioassays. These are especially useful to assess the toxicity of unknown
toxins. For example, the first indications of the toxicity associated with ASP, and subsequently attributed
to domoic acid, were obtained from the AOAC bioassay used for PSP toxin analysis.
Mouse bioassays measure the biological response of the whole animal, thus allowing correlation with
human toxicity effects. They do not require expensive equipment or extensive sample cleanup procedures.
Their main disadvantages are that they involve use of live animals (a practice which has become
increasingly unpopular with animal rights groups), require experienced personnel and careful
standardization of assay conditions to obtain reproducible results, cannot be automated, show lower
sensitivity than other methods, and provide no information on specific toxin composition. This is a
problem especially for samples that contain multiple toxin derivatives (e.g. PSP toxins) or where co-
occurrence of different toxins can cause synergistic or antagonistic effects. False positive or negative
reactions may also occur due to interference by compounds co-extracted during sample preparation.
Bioassays are often less sensitive and precise than analytical methods, and tend to be more reliable for
toxins with acute toxicity, i.e., which yield a low LD50 and short death times.
While false negatives are not tolerable because of their potentially serious consequences to human health,
a high incidence of false positives can cause undue economic hardship, due to lost product and/or the need
for costly confirmatory toxin analysis.
The Asia Pacific Economic Cooperation (APEC) Task Team on Algal Biotoxin Regulations has provided
(Report from the May13-14 1998 meeting) recommendations on toxicity testing as follows:
Monitoring and Management Strategies for Harmful Algal Blooms in Coastal Waters 30
For fresh product, the entire animal is to be tested (except the shell), but if only parts of the animal are
offered for sale, these are the parts that should be tested.
For frozen product, the entire product should be tested (except the shell) but including the liquid
For canned or other sealed, processed product, the entire contents of the can or package should be
tested, excluding the shell if whole animals are included.
A problem was identified for dried product, in that it is not clear whether the product should be tested
before drying, or rehydrated before testing. Problems with salt on dried product were also identified.
These have not yet been resolved within this Task Team.
APEC s Task Team on Analytical Methods and Standards for Marine Algal Toxins has established
performance criteria for various algal toxins.
For PSP, DSP and ASP toxins, it was established that:
A proper sampling scheme must be in place to ensure that a representative sample is analyzed,
The upper limit of uncertainty for the toxin assay method employed must not exceed the specified
action limit.
For DSP (okadaic acid series) toxins:
The extraction and cleanup procedure should recover the entire OA series quantitatively.
Efforts are underway to specify action limits within APEC economies, but this will take some time. It was
also determined that for other toxins, such as NSP toxins, pectenotoxins, yessotoxins and ciguatoxins,
there is at present inadequate information on their link to human oral potency. Therefore, the Task Team
was unable to define action limits, or set performance criteria for these groups of toxins.
Representative sampling is an important consideration given that individual bivalves of the same species
are known to vary greatly in their toxin content even when sampled from the same general location
(reviewed by Bricelj and Shumway 1998). Some of this variation can be attributed to differences in body
size, since small individuals accumulate higher toxin levels per unit body mass than large ones. However,
8-fold differences in PSP toxicity, on average, have been found among individual surfclams sampled from
the same station on Georges Bank, USA (White et al. 1993), and 10-fold differences occurred among
mussels sampled within a 1.2 km distance in the Bay of Fundy (Prakash et al. 1971).
The APEC Task Team on Analytical Methods and Standards is presently undertaking a full evaluation of
methods of detection for various algal toxins, and is compiling a list of available sources of standards and
reference materials, with an aim towards the establishment of standard methods for APEC s member
economies. Current prescriptive analytical methods (as implemented in the EU) are considered a barrier to
effective international trade of