GLOBAL Harmful Algal Bloom - STATUS REPORT 2021
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GLOBAL Harmful Algal Bloom STATUS REPORT 2021
Acknowledgements This Global HAB Status Report summary was prepared based on the special issue Global HAB Status reporting, vol. 102 (Feb. 2021) of the Elsevier Journal Harmful Algae. This publication is sponsored by the Government of Flanders (Belgium) and the In- tergovernmental Oceanographic Commission (IOC) of UNESCO. Thanks are due to all the people that actively participated in and contributed to the compilation and analysis of data as presented in the special issue (vol. 102) of the Journal Harmful Algae and in the IODE Harmful Algal Information System (HAIS). This has helped to build an international cooperative community sharing and analyzing data on HAB events, species and toxin occurrenc- es. Editors: G.M. Hallegraeff (University of Tasmania, Australia), H. Enevoldsen (UNESCO-IOC), A. Zingone (Stazione Zoologica Anton Dohrn, Italy) Authors: G.M. Hallegraeff, K. Aligizaki, Z. Amzil, P. Andersen, D.M. Anderson, L. Arneborg, R.V. Azanza, S.S. Bates, G. Benico, M-Y.D. Bottein, E. Bresnan, F. Arevalo, C. Belin, M.A.C. Branco, D.J. Carbonell, A.D. Cembella, M. Chinain, D. Clarke, J. Correa, K. Davidson, M. Dhanji-Rapkova, X. Dai, H.T. Darius, W. Eikrem, H. Enevoldsen, L. Escalera, H. Farrell, E. Fensin, R. Fernandez Lozano, M. Fernández-Tejedor, C.M. Gatti, C.J. Gobler, H. Guð finnsson, N. Haigh, B. Hay, A.E. Hoeglund, K.L. Howland, K.A. Hubbard, A. Ismael, M. Iwataki, E. Jaffrezic, S.J. Jipanin, U. John, B. Karlson, K. Klemm, J. Kobos, D.M. Kulis, J.H. Landsberg, A. Laza-Martinez, C.P. Leaw, K.A. Lefebvre, S. Lehtinen, M. Lem- oine, A.M. Lewis , N.I. Lewis, W.A. Lim, P.T. Lim, A. Locke, D.C. Louw, D. Lu, N. Lundholm, L. MacKenzie, J.E. Mancera-Pineda, C.H. McKenzie, L.M. Menendez , J.L. Martin, B.H. Maskrey, H. Mazur-Marzec, A. McKinney, S.M. Mendez, M. Montresor, P. Mozetič, L. Naustvoll, T. Orlova, Y. Pazos, A. Peña, G.C. Pitcher, M. Poelman, M. Poulin, P. Provoost, M. De Rijcke, J.-P. Quod, M. Revilla, L. Rhodes, M.L. Richlen, A. Rochon, W.A. Rourke, S. Sakamoto, M.G. Scarratt, L. Schweibold, R. Siano , A. Silva, J.L. Smith, A.R. Solow, D. Soudant, S. Suikkanen, I. Sunesen, S. Swan, M. Starr, S. Taş, C. Totti, P.A. Tester, V.L. Trainer, A.D. Turner, T. Wells, J.J. West, A.T. Yñiguez, A. Zingone For bibliographic purposes this document should be cited as: G.M. Hallegraeff et al. (2021). Global HAB Status Report. A Scien- tific Summary for Policy Makers. G.M. Hallegraeff, H. Enevoldsen, A. Zingone (Eds). Paris, UNESCO. (IOC Information Document, 1399.) Design: Leif Bolding, Dept of Biology, University of Copenhagen Cover image credits: Cynthia McKenzie, DFO Canada IOC/INF-1399 2 Global Harmful Algal Bloom Status Report 2021
GLOBAL Harmful Algal Bloom STATUS REPORT 2021
• An extremely variegated picture of harmful algal bloom types and their socio-economic impacts at the
regional and subregional scale has emerged from a comprehensive overview of OBIS and HAEDAT data
in the period 1985 to 2018.
• The diversity of the HAB events parallels that of the causative species, which show different ranges and
ecological characteristics, as well as highly variable responses to environmental changes.
• The intensity and frequency of specific blooms vary at regional and local scale, with increasing or
decreasing trends and sudden occasional outbursts, but with no uniform global trend that can be dis-
cerned from that of increased observational efforts.
• In many cases intoxications and other adverse effects on human health are kept under control through
increased monitoring activities, but impacts on human activities such as aquaculture, fishery, use of
natural marine resources and tourism keep on posing economic activities at risk in many regions.
Among the approximately 10,000 beneficial species of extensive and detailed overview of the huge amount
marine phytoplankton in the world’s oceans today, of information on harmful species, their spatial and
some 200 taxa can harm human society through the temporal distribution and the trends of HABs they have
production of toxins that threaten seafood security and caused has never been attempted so far.
human health. These toxins are also responsible for wild
This lack of a synthesis of the relevant data has ham-
or aquaculture fish-kills, may interfere with recreation-
pered a sound global assessment of the present sta-
al use of coastal or inland waters, or cause economic
tus of phenomena related to harmful algae. Following
losses. Non-toxic microalgae attaining high biomass can
the lead of the International Panel for Climate Change
also cause Harmful Algal Blooms (HABs) by producing
(IPCC) consensus reporting mechanism, and to comple-
seawater discolorations, anoxia or mucilage that nega-
ment the World Ocean Assessment, the need has been
tively affect the environment and human activities.
expressed for a Global HAB Status Report compiling an
The most frequently asked questions about harmful overview of Harmful Algal Bloom events and their soci-
algal blooms are if they are increasing and expand- etal impacts; providing a worldwide appraisal of the oc-
ing worldwide, and what are the mechanisms behind currence of toxin-producing microalgae; aimed towards
this perceived escalation. These questions have been the long term goal of assessing the status and probabil-
addressed in several review papers concerning HAB ity of change in HAB frequencies, intensities, and range
trends at various scales, where evidences of expansion, resulting from environmental changes at the local and
intensification and increased impacts of harmful algal global scale. This initiative was launched in April 2013 in
blooms have been gathered from a selection of exam- Paris by the IOC Intergovernmental Panel on HABs (IOC/
ples that have gained high prominence in the scientific IPHAB), and has been pursued with the support of the
world and in society 1,2,3,4. Eutrophication, human-me- Government of Flanders and hosted within the IOC In-
diated introduction of alien harmful species, climatic ternational Oceanographic Date Exchange Programme
variability, and aquaculture have all been mentioned (IODE) in partnership with ICES, PICES and IAEA.
as possible causes of HAB trends at various spatial and
As a first step towards a global HAB status assessment,
temporal scales 5,6.
a Special Issue of the journal Harmful Algae (vol. 102,
Over the last 40 years, the capacity and monitoring ef- February 2021) has been published comprising 12
forts to detect harmful species and harmful events have papers 7-18 each presenting an overview of toxic and
significantly increased, thus increasing the reporting of non-toxic HABs in a specific area of the world’s seas.
harmful events across the world’s seas. The resulting The regional overviews build on existing literature and
information is mostly scattered in the ever growing lit- exploit the information gathered in two relevant data-
erature, with data from statutory monitoring programs bases, both incorporated into the Ocean Biodiversity
often not published in peer review journals, while an Information System (OBIS).
Global Harmful Algal Bloom Status Report 2021 3
Global Harmful Algal Bloom data available
The data bases available on HAB events (HAEDAT) and others (including foam and mucilage production). In a
distribution of the causative microalgae (OBIS/HAB- number of HAEDAT records, a single incident was cat-
MAP) described at the end of this brochure have both egorized into multiple event types, such as both water
limitations and need expert judgement to be correctly discoloration and high phytoplankton count (11% were
used. For example, because of inconsistent HAB report- multiple event types) which affected aquaculture ac-
ing procedures and different observational efforts, no tivities rather than human health in most cases except
direct proportionality exists between events recorded for Ciguatera. Among all events linked to seafood toxin
in HAEDAT and toxicity in a given region. Paradoxical- syndromes, Paralytic Shellfish Toxins (PST) accounted
ly, areas with more HAB event records rather reflect for 35%, Diarrhetic Shellfish Toxins (DST) 30%, Ciguatera
effective management and may have much lower risk Poisoning (CP) and marine and brackish water cyano-
of intoxications compared to areas with insufficient bacterial toxins each 9%, Amnesic Shellfish Toxins (AST)
monitoring and/ or rare events. As for trends, changes 7%, and others 10% (including Neurotoxic Shellfish Tox-
in monitoring and regulatory approaches may have an ins (NST), Azaspiracid Shellfish Toxins (AZT), and toxic
impact on the number of aquaculture bans and hence aerosols) (Fig. 1).
of the events reported. Similarly, maps of toxic species
Human health toxins. With some exceptions for a few
often reflect the distribution of taxonomists, while geo-
warm water and cold water species, potentially toxic
graphic ranges rarely include long stretches of African
species are widespread, each region of the world har-
and south Asian coasts. Therefore, awareness of these
bouring a high number of them. However they do not
possible biases and deep knowledge of regional harm-
cause harmful events everywhere, nor with the same
ful species and HAB distribution are necessary to en-
intensity at different places. DST events have a much
sure a correct interpretation of the data in the current
higher incidence in European seas, and in the Mediter-
literature and in the databases.
ranean, while they are less common than PST events
As of 10 December 2019 a total of 9,503 HAEDAT events in Canadian waters, along the Atlantic US coasts, in the
had been entered from across the globe, comprising Caribbean and South America and Phillippines. (Fig. 2).
48% seafood biotoxin, 43% high phytoplankton counts Ciguatera is mostly confined to the subtropical Pacific
and/or water discolorations causing a socio-economic and the Caribbean, with recent expansion in Macaron-
impact, 7% mass animal or plant mortalities, and 2% esia. Other types of toxicity from benthic microalgae,
HAB types HAB TYPES
mucus
mass 1% other
mortalities
1%
7%
SEAFOOD TOXINS
cyano high phytoplankton
seafood counts + water
9% discolorations
aerosol AZT
toxins
other PST 48% 43%
CP 1% 8% 35%
9%
AST
7%
NST
1%
DST
30%
Fig.1. Partitioning of global HAEDAT events (as of Dec 2019) into the HAB types seafood
toxins, high phytoplankton counts +water discolorations, marine mortalities; and the further
breakdown of seafood toxins into different types of toxins, the most commonly reported
being PST and DST.
4 Global Harmful Algal Bloom Status Report 2021
90%
80%
70%
60%
672
A
3551
599 ECA EUR
WCA 816
702 50%
CCA MED NAS
446672
3551 SEA PAC
599 ECA EUR
333
40%
473
WCA SAM
29
816
702 IND
CCA 257
MED
57 ANZNAS
187
446 BENG SEA
30%
PAC
333 473
SEAFOOD TOXINEUR=Europe
ECA =East Coast America syndromes by region
29 20% SEA=South East Asia
CCA=Central
100%
SAM MED=Mediterranean
America Caribbean IND NAS=North Asia
257 187 Aerosols
SAM=South America BENG=Benguela
57 Current
10%
ANZ
ANZ=Australia New Zealand
BENG Ocean AST
WCA=West
75 Coast America IND=Indian PAC=Pacific
AZP
B
0%
50 SEAFOOD
TYPE TOXIN
OF HAB syndromes
EVENTS by region
BY REGION ECA CCA WCA
Ciguatera
ANZ NAS MED SEU NEU Pacific
100% Cyanotoxins
25 Aerosols
Water
DST
Discoloration
NST AST
Seafood Toxins
75 0
672
ECA CCA 599 ECA SEA NAS
SAM WCA ANZ
3551 Other
PSTEffects
AZP
EURIND BENG MED EUR PAC
WCA 816
Mass Mortalities
Others
50 CCA MED
702
NAS Ciguatera Count
High Phytoplankton
446
SEA PACMucus Cyanotoxins
333 473
25 29
SAM IND DST
257 187
57 ANZ NST
0 BENG
PST
C SEAFOOD
ECA CCA SAM TOXIN
WCA ANZ
SEAFOOD SEA EVENTS
TOXIN NAS INDBYBENG
syndromes byREGION
MED EUR PAC
region
Others
100%
Aerosols
AST
75
AZP
50 Ciguatera
Cyanotoxins
25
DST
NST
0
PST
ECA CCA SAM WCA ANZ SEA NAS IND BENG MED EUR PAC
Others
Fig.2. A: Total number of recorded HAB events in each of twelve geographic regions. B:
Relative abundance of different types of harmful algal phenomena; and C. Seafood toxin
syndromes. Paralytic Shellfish Toxins were dominant in East Coast America (ECA), South
America (SAM), West Coast America (WCA), South East Asia (SEA) and North East Asia
(NAS), Diarrhetic Shellfish Toxins were prevalent in the Mediterranean (MED) and Europe
(EUR), and Ciguatera was predominant in the Indian Ocean (IND) and tropical Pacific
(PAC). Australia/New Zealand (ANZ) and Central America/Caribbean (CCA) displayed mix-
tures of events, while Benguela (BENG) had a large proportion of other syndromes.
namely by Ostreopsis spp., are recorded in the Mediter- animals and present continuous impacts, or more oc-
ranean Sea and along the Brazilian coasts. ASP-related casional outbursts, such as marine mass mortalities by
problems affect mainly both Atlantic and Pacific Canadi- Alexandrium catenella in St Lawrence Estuary in 2008.
an and US coasts, and the UK, while Domoic Acid in sea- In South America, the greatest economic losses are pro-
food rarely exceeds regulatory limits elsewhere despite duced by salmon deaths associated with Pseudochat-
the wide range and intense blooms of Pseudo-nitzschia tonella verruculosa and Alexandrium catenella in Chile
species over many coastal areas. Neurotoxic Shellfish and tuna deaths related to Tripos furca and Chattonella
Toxins (NST) are confined to Florida, with a single out- in the Mexican Pacific. In the Philippines and in Malay-
break reported from New Zealand. sia, fish-killing algal blooms by Chattonella, Karlodini-
um, Margalefidinium (Cochlodinium) polykrikoides, and
Fish and shellfish kills are a dominant issue in many
Prorocentrum cordatum are a recent problem. In South
regions, where they may affect reared or wild marine
Global Harmful Algal Bloom Status Report 2021 5
Africa, high biomass dinoflagellate blooms by Gonyau-
lax, Lingulodinium, Prorocentrum, Protoceratium and
Tripos are associated with mass mortalities of marine
life from anoxia during decay of the blooms. In coun-
tries of the west Pacific coasts (China, Japan, Korea and
Russia), finfish mortalities by Chattonella, Margalefidi-
num, Karenia and Karlodinium, and shellfish mortalities
by Heterocapsa circularisquama are of greatest con-
cern (Fig. 3). In the Kattegat-Skagerrak, Eastern North
Sea and Norwegian Sea major fishfarm mortalities
were caused by Chrysochromulina leadbeateri in Nor-
way 1991 and 2019, Prymnesium polylepis in the Kat-
tegat-Skagerrak in 1988, and Pseudochattonella spp. in
the Kattegat-Skagerrak since 1998. Interestingly, several
fish kills in distant and presumably ecologically different
areas are caused by the same species, but other spe-
cies, such as Heterocapsa circularisquama, Karlodinium
spp., and Prymnesium polylepis are quite specific to
certain areas.
Impacts other than fish kills and toxicity to humans are
linked to region-specific resources or particular groups
of species. For example, dense blooms of non-toxic di-
atoms and dinoflagellates can cause nutrient depletion
and bleaching of the farmed red algae nori, with consid-
erable economic impacts in China. HABs by cyanobac-
teria, either toxic or causing discolorations, have an im-
pact mainly in the Baltic and Brazilian coasts, although
sscattered reports from other areas also exist. In areas
with intense tourism, such as the Mediterranean Sea,
the Brazilian coasts and the Caribbean, severe im-
pacts derive from high biomass blooms, discoloration
and mucilages, which may be caused by toxic and/or
non-toxic species.
Fig. 3. Finfish killing HABs are of great concern in China, Japan
and Korea, but the causative species vary regionally 11
Massive mortality of marine fish due to harmful algae. St Helena, South Africa. Photo: Grant Pitcher
6 Global Harmful Algal Bloom Status Report 2021
Analysis for Global HAB trends
A much reproduced map of Paralytic Shellfish Poison- (belonging to the dinoflagellate genus Dinophysis), a 7x
ing (PSP) in 1970 and 2009 4 , largely based on oral re fold increase of global observations of the causative or-
ports presented at HAB conferences, mostly reflects in- ganisms of Amnesic Shellfish Poisoning (mainly in the
creased awareness of the distribution of the causative diatom genus Pseudo-nitzschia), and 6x fold increase
dinoflagellate organisms, rather than the actual occur- of global observations of the main causative species of
rence or abundance of Paralytic Shellfish Toxins (PST) in Paralytic Shellfish Poisoning (belonging to the dinofla-
seafood or the incidence of human poisonings. gellate genus Alexandrium) (Fig. 4.). The latter poison-
ing syndrome is also caused by the less-widespread di-
This map mostly reflects increased awareness of the
noflagellates Gymnodinium catenatum and the tropical
distribution of the causative dinoflagellate organisms,
Pyrodinium bahamense.
rather than the actual occurrence or abundance of Par-
alytic Shellfish Toxins (PST) in seafood or the incidence However, a meta-analysis of the global HAEDAT and
of human poisonings. OBIS data sets shows no conclusive evidence for a sta-
tistically significant, uniform trend of “increased global
Exploring trends by examining the total number of
frequency and distribution of HABs” in the period 1985
HAEDAT events between 1985 and 2018, a 4x fold in-
to 2018 20. When statistically correcting regional HAE-
crease is evident for positive global records of the main
DAT events for varying monitoring capabilities or cov-
causative species of Diarrhetic Shellfish Poisoning DSP
OBIS Causative
OBIS
OBIS Organisms
Causative
Causative
Organisms
Organisms HAEDAT
HAEDAT Toxic
HAEDAT
Toxic
ToxicEvents
Events
Events Human
Human
Poisonings
Poisonings
3 3
3300 3300
1300 1300
AA Dinophysis
Dinophysis 3 3
3300 3300
120 120
1300 1300
DD 3 3 Dinophysis
Dinophysis DSP
DSP
DSTDST GG DSP
DSP
150 150 n=102,441
n=102,441
n=84,392
n=84,392 100 100 1300 1300 Dinophysis 3
Dinophysis 3
5000 5000 150 150
5000 5000 3300 3300 n=102,441
n=102,441
n=84,392
n=84,392 3300 3300
1300 130
130 130 150 150 80 80 150 150 n=102,441
n=102,441 150 150
130 130 150 150 5000 5000 5000 5000
60 60
661 661 51 51
661 66151 51 130 130 150 150 130 130 150 15
40 40
661 661 51 51
661 661 51 51
20 20
0 0
1980 1980 2000 2000 2020 2020 1980 1980 2000 2000 2020 2020
1985
1987
1985
1989
1987
1991
1989
1993
1991
1995
1993
1997
1995
1999
1997
2001
1999
2003
2001
2005
2003
2007
2005
2009
2007
2011
2009
2013
2011
2015
2013
2017
2015
2017
1980 1980 2000 2000 2020 2020
150/3150/3 B B Pseudo-nitzschia
Pseudo-nitzschia
150/3150/3 E E Pseudo-nitzschia
Pseudo-nitzschia HH
n= 160,128
n= 160,128
n=128,282
n=128,282 30 30
150/3150/3
n= 160,128
n= AST
ASP AST
ASP
160,128
n=128,282
n=128,282
Pseudo-nitzschia
Pseudo-nitzschia
150/3150/3
ASP
ASP
25 25
n= 160,128
n= 160,128
Number of records
Number of records
20 20
of records
of records
15 15
10 10
5 5
Number
Number
0 0
80/1480/14 80/1480/14
6/2 6/2
1985
1987
1985
1989
1987
1991
1989
1993
1991
1995
1993
1997
1995
1999
1997
2001
1999
2003
2001
2005
2003
2007
2005
2009
2007
2011
2009
2013
2011
2015
2013
2017
2015
2017
1980 1980 2000 2000 2020 2020 -5 -5 1980 1980 2000 2000 2020 2020
194 194 194 194
Alexandrium
Alexandrium
4 4
Alexandrium
Alexandrium
1980
2/6 1980
I I 2000
41/08 2000
41/08 4 4 2020
2020 PSP
P
PSP
PS
2/6
41/08 41/08
n=26,004
n=26,004
PST
PSP PST
PSP
n=19,887
n=19,887
2/6 2/6
n=26,004
n=26,004
n=19,887
n=19,887 99/3 99/3 136/1
99/3 136/1
99/3 Alexandrium
Alexandrium
C C F F I 50/1
I
491 491
491 491
2/6 2/6 41/08 41/08
1/631 1/6350/1
1
2/6
50/1
2/6
2/6
2/6 4 4
41/08 41/08
41/08 41/08 muirdnm axueirlA dnaxelA 1/631 1/631 50/1 2/6 2/6 n=26,004
4
n=26,004
4 41/08 41/08
3/99 3/99
muirdnm
axueirld
AnaxelA 120 120 3/99 3/99 6/2
40044,699211=4n
0044,699211=n 1/05 1/05
400,624=0n0,62=n
80/14 80/14
1/05 1/05
6/2 6/2 2555/165 2555/165 194 194
561/5552561/5552
80/14 80/14
4 4
6/2
561/5552561/5552 4 4 muirdm naau
uxxiieerrd
dllA
An
naaxxeellA 1 / 6 3 1
A 1/631 1/631
194 194 1/ 6 3 1 4 4
m 100194100 1/6194
31 1/631 4 4 3/99mu3i/r9d9m n
muuiirrd
dm
mn
naau
uxxiieerrd
dllA
AnnaaxxeellA
A 1/631 1/631 3/99 3/49090,624=0n 0,62=n99/3
99/3
4 06 4 06
5/55 4 5/55 460 60 136/1
5/55 4 5/55 460 60 1/05 1/04500,624=0n0,62=n
06 06
4
40000,,6
62 24
4==00n n0
0,,6 2
2==n
680 n 80 1/05 1/05 99/3 50/199/3 6/23 6/23
55/5 55/5136/1 136
99/3 99/3 561/555261/5552
6/23 6/23
55/5 55/5 136/1 136/1 Alexandrium Alexandrium
92 92
50/1 561/5555261/5552
561/5555261/532/6 552 03/32/6
92 92 561/555261/532/6 552 03/32/6 n=26,004 n=26,004 5 5 50/1 50/1 4 9 4 0 3/ 4 9 4
2555/165 2555/165
5 5 50/1 50/1 494 03/494
2555/165 06
2555/16506
60 60 2555/165 06
2555/165 06 5/55 5/0565 06
5/55 5/0565 06 29494/30 29494/3060 60 5/55 56//5253 6/23
494/30 494/30 60 60
5 / 5 5 5 / 5 5
6/23 6/23
6/23 6/23 5 99225 9922 32/6 60 60
55/5 55/5
55/5
32/6 55/5
6/ 2 3 6/23
40 992240 9922 32/6 55/5 32/6
55/5
03/494 03/494
5
muc5ificapm/m 5
uc5
32/6
uiftiucn
aipm/m
32/6
/aullteunneim
ta/camlleuniredtnaac xm
eluAirdnaxelA
03/
03/
muc5 5 03/494 03/494 494/30 29 2
5ificapm/umc5uiftiucanpim
/m
/aultleunneim
ta/cam
lleuniredtancaxmeluAirdnaxelA
29 29 494/30494/30
494/30 esnemaheasbnm em ua inhidaobrm
yPuinidoryP 5 5 5
494/30 494/30 esnemaheasbnemmuainhiadbormyPuinidoryP 5 5 mutanetamcum
taunineitdaocnm
muyiG
nidonmyG
20 20 mutanetamcum
taunin
etidaoc nmmuyin
GidonmyG
0202 0202 0002 0002 0891 0891
0202 0202 0002 0002 0891 0891 OBIS
OBIS
Species
Species
Occurrences
Occurrence
0 0 mucificampu/m
cifuictuanpi/m
m/uatlulennim
et/aacllm
enueirt
mucificampu/m
cifuictuanpi/m
m/uatlulennim
et/aacllm
enueirt
mucificampu/m
cifuictaupn/im
mucificampu/m
m/uatlulennim
cifuictaupn/im
et/aacllm
m/uatlulennim
enueirta
et/aacllm
dcnamxeuliA
enueirta
rdnaxelA
dcnamxeuliA
rdnaxelA Alexandrium
Alexandrium Alexandrium
Alexandrium
Alexandrium catenella/minutum/pacificum
catenella/minutum/paci
catenella/minutum/pacificum
Alexandrium catenella/minutum/pacificum
catenella/minutum/pacificum
catenella/minutum/pacificum esnemaehsanbemuai
1985
1987
1985
1989
1987
1991
1989
1993
1991
1995
1993
1997
1995
1999
1997
2001
1999
2003
2001
2005
2003
2007
2005
2009
2007
2011
2009
2013
2011
2015
2013
2017
2015
2017
esnemaehsanbemuai
Alexandrium
Alexandrium
catenella/minutum/pacificum
catenella/minutum/pacificum
Alexandrium
Alexandrium 1980 1980 eessnneem
catenella/minutum/pacificum
catenella/minutum/pacificum
maehsanb2000
aehsanbemauhinaib
emauhinaib
d2000
2020 2020 Pyrodinium
om
dom
ryuPinidoryP
Pyrodinium
Pyrodinium
Pyrodinium
ryuPinidoryP
bahamense
Pyrodinium
Pyrodinium
bahamense
bahamense
bahamense
bahamense bahamense m utanem
mutanem
tauctm
tauctm
anueintai
anueintai
1980 1980 2000 2000 2020 2020 Pyrodinium
Pyrodinium
Pyrodinium
bahamense
Pyrodinium
bahamense
bahamensebahamense mutanem
mutanem
tauctm
tauctm
anueitnaidcom
nu
anueitnaidcom
nu
minyG Gymnodinium
idonmyG
minyG Gymnodinium
idonmyG
Gymnodinium
catenatum
Gymnodinium
catenatum
catenatum
catenatum
0002 0002 Gymnodinium
08Gymnodinium
91 0891 catenatum catenatum
Gymnodinium
Gymnodinium
catenatumcatenatum
0202 0202
0202 0202 0002 0002 0891 0891
0002 0002 Gymnodinium
08Gymnodinium
91 0891 catenatum
catenatum 1980 198
0202 0202
0202 0202 0002 0002 0891 0891 1980 1980 2000 2000 2020 2020
Fig.4. Increases from OBIS data between 1985 and 2018 of the total number of global observations 19801980 20002000 20202020
of the causative organisms of: A. Diarrhetic Shellfish Poisoning (DSP); B. Amnesic Shellfish Poison-
ing (ASP); and C. Paralytic Shellfish Poisoning (PSP), together with D, E, F. The number of records of
HAEDAT Toxic Events of DST, AST and PST.
Global Harmful Algal Bloom Status Report 2021 7
A 45M AUD tuna aquaculture mortality in Port Lincoln, Australia, 1996, caused by the HAB species Chattonella marina. Photo: B.Munday and G.Hallegraeff The toxic dinoflagellate Karenia brevis produces bre- Cells on a sampling net of the toxic benthic dinoflagellate Gambierdiscus. vetoxins, which can cause fish kills, contamination of which produces toxins that may cause ciguatera poisoning. French Poly shellfish, and respiratory problems in humans. Gulf of nesia. Photo: M. Chinain. Mexico, USA. Photo: NOAA 8 Global Harmful Algal Bloom Status Report 2021
Trends
Trends
Trends
Trends ininUS inUS
inUS US
HABsHABs
HABs
HABs
Trends
Trendsin inUSUSHABs
HABs
PST; non- significant trend NST;
NST;
NST;
NST; non-
non-
non-
non- significant
significant
significant
significant trendtrend
trend
trend
PST;
PST;
PST;non-
non-
non-significant
significant
significant trend
trend
trend
NST; non- significant trend
PST; non- significant trend
AST;
AST;
AST;
AST; significant
significant
significant
significant increase
increase
increase
increase DST;
DST;
DST; non-
non-
non- significant
significant
significant increase
increase
increase
DST; non- significant increase
AST; significant increase DST; non- significant increase
Total
Total
Total
Total HAEDAT
HAEDAT
HAEDAT
HAEDAT numbersA
numbers
numbers
numbers Grids
Grids
Grids
Gridswith with
with
with >1
>1>1>1 HAEDAT;B
HAEDAT;
HAEDAT;
HAEDAT;
AAA BB B
Total HAEDAT numbersA Gridsslight
slight
slight
with increase
increase
increase
>1
slight increase HAEDAT; B
slight increase
Fig. 5. The frequency of PST , NST, AST, and DST events in the US (defined as at least one closure in a defined region
or HAEDAT zone in a given year derived from HAEDAT in the period 1990-2019. From 7
erage (HAEDAT adjusted for OBIS microalgal records), increase while DST shows a non-significant increase 7
regional cases of both increases, decreases or stable (Fig. 5). Exploring trends of human Ciguatera Poison-
number of harmful event incidents were demonstrated ings, in Hawaii poisonings have been decreasing, in
for different regions. While using OBIS microalgal data French Polynesia and the Caribbean numbers remained
as a proxy for sampling effort may not be fully represen- stable, whereas CP is a new phenomenon in the Canary
tative of HAB sampling in all regions, this approach con- Islands (Fig. 6).
firms sampling effort as a key driver of observed region-
While biotoxins in marine mammals in the Arctic Pacific
al patterns. Similar regional variations emerge using the
have increased, in the Philippines and Malaysia blooms
number of geographic grids with HAB events, which is
of the PST producer Pyrodinium bahamense have stabi-
less prone to inconsistencies in sampling effort. Within
lized or decreased compared to the 1990s, when they
regions, trends are also heterogeneous and concern
were a great concern, while other PST-producing spe-
selected HAB types. In the US, the toxin syndromes PST
cies have increased. DSP problems in Norway have de-
and NST thus shows no statistically significant change
creased, and also fish kills in Seto Inland Sea of Japan
over the period considered, but AST shows a significant
and on the Atlantic Canadian coast, while mucilages
Global Harmful Algal Bloom Status Report 2021 9
SCUBA Divers Collecting near shore sediment cores for A. catenella cyst analysis in Newfoundland and Labrador, Canada. Photo: C. McKenzie Sampling for benthic micralgae causing Ciguatera poisoning. French Polynesia. Photo: M. Chinain. 10 Global Harmful Algal Bloom Status Report 2021
Number of Poisoni
600
400
200
C. Ciguatera Human Poisonings 0
C. Ciguatera Human Poisonings
Number of Poisonings
Hawaii Canary Islands
B. Ciguatoxins
80
80
in Fish Hawaii 40
60 30
60
40 20
40
20 10
20
0 0
0
Ciguatoxins+in+Fish+
French Polynesia Caribbean and Mexico
Poisonings
800
French Polynesia
Poisonings
800
600
600
400
400
200
Ciguatoxins+in+Fish+
200
0
ofof
0
Number
Canary Islands
Number
40 Canary Islands
40
30
Fig. 6. Trends
30
20 between 2000 and 2018 in the number of human ciguatera poisoning cases in Hawaii, French Polynesia, Canary Islands,
the Caribbean
20 (light green) and Mexico (dark green). Adapted from 18.
10
10
0
0
in the Adriatic Sea are less frequent nowadays. What This is only the first of hopefully many future analy-
seems somehow more Caribbean
commonand Mexico
is the spreading of HAB ses of the HAEDAT database. The HAEDAT and HAB-
Caribbean and Mexico
events into new areas, such as the ciguatera species in MAP-OBIS databases are currently being prepared for
Macaronesia, problems related to Pyrodinium baha- integration within OBIS along with the development
mense in Florida, Ostreopsis in the Mediterranean area, of a specific HAB user interface (https://hab-dev.iode.
and expanding red Noctiluca in the Australian region org/). With the IOC UNESCO Reference List of toxic spe-
and green Noctiluca in the Arabian Sea. All regional cies in WoRMS this will be launched as the IOC Harmful
overviews point at intensified monitoring efforts, due Algal Information System, HAIS. Improvements include
to increased aquaculture and tourism, and the region- ease of data entry and Quality Control, improved map-
al emergence of new HAB syndromes or impacts, as a ping options combining data from HAEDAT and HAB-
key driver of the increasing number of records of HAB MAP/OBIS and more user-friendly interface. Only with
events. The overall conclusion is that broad statements ever improving and better harmonized global data sets
on global HAB trends increasing are not supported by can we answer questions on the relationships between
the meta-analyses, but trends in HABs are best assessed HABs, climate, eutrophication and aquaculture with
on a species-by-species and site-by-site basis. confidence and improve our forecasts of future trends.
Cells of the toxic benthic dinoflagellate Gambierdiscus. Photo: M. Underwater mussel lines and an Alexandrium bloom approaching
Chinain. from the left. Gulf of St. Lawrence, Canada. Photo: C. McKenzie.
Global Harmful Algal Bloom Status Report 2021 11Developing a Global Harmful Algal Information System
Access to data on HAB events, impacts and the caus- economic, and/or ecological impact or a management
ative species is the basis for enabling the preparation action. A harmful algal event is defined as at least one
of a Global HAB Status Report. The establishment of of the following types, all causing a socio- economic im-
the Harmful Algal Information System (HAIS; http:// pact: (i) water discolorations, mucilages, scum or foams
hais.ioc-unesco.org) in collaboration with the IOC In- produced by non-toxic or toxic microalgae; (ii) biotoxin
ternational Oceanographic Data Exchange (IODE) pro- accumulation in seafood above levels considered safe
gramme is a response to the need for an authoritative for human consumption; (iii) harmful algae-related
and co-ordinated world-wide on-line source of informa- precautionary bans of shellfish or other invertebrate
tion about harmful algae. HAIS consists of databases on harvesting or closures of beaches to protect human
harmful algae developed in partnerships between IOC health; and (iv) any event where humans, animals, and
UNESCO, the International Council for the Exploration other organisms are negatively affected by microalgae.
of the Seas (ICES), the North Pacific Marine Science Or- Events are reported even when there is no information
ganization (PICES), and the International Society for the about the causative organism, but negative records or
Study of Harmful Algae (ISSHA). HAIS presently consists changes in monitoring activities are not recorded. The
of two main databases: data are summarized into individual events, with infor-
mation on start and finish dates for the event, area over
OBIS-HABMAP, the Database on the geographic range
which the event has been detected, maximum cell and
of Harmful Species (http://ipt.iobis.org/hab). Based on
toxin concentrations, types of impact and geographic
published information, HABMAP provides biogeograph-
range covered. The data are searchable by country, re-
ic information, as referenced maps, of the microalgal
gion, syndrome/type, and year and can be downloaded
species that are listed in the IOC-UNESCO Taxonomic
as csv files for further analysis. Data have been entered
Reference List of Harmful Microalgae 19. The list under-
routinely in HAEDAT from a number of countries since
goes continuous revision since its inception in 1997.
the mid-1990s with some countries also entering his-
The database is being compiled by 12 Regional Editorial
toric data extending back to the late 1800s. Different
Groups. In OBIS, the data from quality controlled HAB-
geographic regions contain varying numbers of HAEDAT
MAP databases can be shown along with all other data
reports, with the largest number of records available
entries or as separate queries for quality controlled
for north-western Europe and the most limited da-
data. Because entries concern these taxa regardless of
ta-sets for South America, Australia/New Zealand, and
the intraspecific variability in toxicity and impacts, the
countries of the Benguela Current Region.
database provides a worldwide map of potential risks
related to the occurrence of toxic species. A detailed description of HAB-related databases and
suggestions for their future development are presented
HAEDAT, the Harmful Algal Event Database (http://
in Zingone et al. (2021) 20. A meta-analysis of the data
haedat.iode.org). HAEDAT is the only existing open ac-
aggregated by regions is presented in Hallegraeff et al.
cess database holding information about harmful algal
(2021) 21.
events from across the globe. HAEDAT data are sum-
marized into ‘events’ associated with a negative health,
12 Global Harmful Algal Bloom Status Report 2021References
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Global Harmful Algal Bloom Status Report 2021 13Global Harmful Algal Bloom
Status Report 2021
The most frequently asked questions about harmful
algal blooms are if they are increasing and expanding
worldwide, and what are the mechanisms behind
this perceived escalation. These questions have been
addressed in several review papers concerning HAB
trends at various scales, where evidences of expan-
sion, intensification and increased impacts of harmful
algal blooms have been gathered from a selection of
examples that have gained high prominence in the
scientific world and in society. Eutrophication, hu-
man-mediated introduction of alien harmful species,
climatic variability, and aquaculture have all been
mentioned as possible causes of HAB trends at various
spatial and temporal scales.
The lack of a synthesis of the relevant data has ham-
pered a sound global assessment of the present
status of phenomena related to harmful algae. This
Global HAB Status Report for the first time compiles
an overview of Harmful Algal Bloom events and their
societal impacts; providing a worldwide appraisal of
the occurrence of toxin-producing microalgae; aimed
towards the long term goal of assessing the status and
probability of change in HAB frequencies, intensities,
and range resulting from environmental changes at
the local and global scale. This initiative was launched
by the IOC Intergovernmental Panel on HABs (IOC/
IPHAB), and has been pursued with the support of the
Government of Flanders and hosted within the IOC
International Oceanographic Data and Information
Exchange Programme (IODE) in partnership with ICES,
PICES and IAEA.
For more information:
http://hais.ioc-unesco.org
One Planet,
ioc.unesco.org One Ocean
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