8/7/2021

Benthic harmful
dinoflagellate community
dynamics:
A case study from Perhentian
Islands (Malaysia)
Po Teen LIM,
Mustapa N., Lee LK, Lim ZF,
Hii KS, Gu H, Leaw, CP.

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Ciguatera Fish Poisoning

Source: Journal of American Medical Association

3

Ciguatera epidemic

42

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The toxins• Maitotoxins and Ciguatoxins• A class of lipid polyether compoundswith low molecular weight.
• Clinical symptoms: gastrointestinal,neurological and cardiovascular.
Recovery could take months to years.
• At present, there is no easy method toroutinely measure the toxins.
• No antidote of CFP.
• Under-diagnosed, due to limitation in
toxin analysis laboratory.

5Live reef food fish trading: Problem of ciguatera and its impacts
Increase in demand for live reef
fishes from SEA and Indo-Pacificregions has resulted inoccurrence of ciguatera cases inareas far from the origin (Chen2015).
2001: Malaysia supplied
10,000MT of live wild catchgroupers.
Live fishes from Sabah have beenreported to cause CFP in Hong
Kong (Sadovy, 1997, 2001).

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Photo credit: Y. Sadovy

Live Reef Food Fish Trade (LRFFT)
Problem of ciguatera and its impacts
Example: Hong Kong

Global hub for > USD 1 billion LRFFT (Feb 2018)

CFP Outbreaks in Hong Kong

10050

‘97

‘04

7M a l aysi a: 2 0 1 0 C F P O u t brea k
22 (5 families) felt sick after consuming the redsnapper on Sept 8, 2010; 11 were admitted tohospital.
Contaminated fish were bought from Jeli, which wasbought from Far Frozen Fish Sdn Bhd, Pasir Puteh(red snapper, Batch no MRH-5000 25kg)(adapted from Nik Khair0l Reza et al. 2011)84

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M a l aysi a: C F P i n S a b a h, De c ember 2 0 1 7
Symptoms persisted [muscle weakness, itchiness]

Symptoms developed
8 Dec[diarrhea, bradycardia,numbness, itchiness,burning sensations]

Episodic: reactivated by food
6 months

1-2 months
6 Dec 201713 Dec2 affected
after
consumedfish

1 victim
hospitalized

Action taken
9 Jan 2018

21 Feb

8 Mar

Consulted by thevictim,asked forassistance from
SFD to collect thefish samples

Fish species
confirmed

Ciguatoxinsconfirmed byLCMS/MS

Lee et al., Medical Journal of Malaysia

9M a l aysi a: C F P i n S a b a hFishes collected from victim’s home

The fish species were identified asLutjanus bohar and Lutjanus sebae
We conducted species
identification using molecularanalysis

Ciguatoxin confirmation byLCMS/MS in Lutjanus bohar only.
(unpublished data)
Lee et al., 2019. Medical Journal of Malaysia,
Dao et al., In prep.

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Climate change and Benthic HABs

Global SST increases of 0.4–1.4 °C by 2055 will
promote growth rates of many BHABs (Testeret al. 2020).
Northward expansion of BHABs and CFPevents.

11BHAB species generally occur at various
bottom substrata, but dominating
specific habitats with different ecologicaloptima (i.e. temperature, light, nutrientsetc.).

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RESEARCH in BHABs
how fine-scale difference insubstrates affects thedistribution and abundanceof BHABs, and by inference
the local risk of toxicity

13Aim
To demonstrate an alternative sampling approach for BHAB studies,
To establish spatial and temporal patterns of BHAB assemblages
and the associated environmental variables,
To assess the effect of reef degradation on BHAB communities.

147

Study site

8/7/2021

Perhentian Islands
Marine ParkA reef flat of 100 × 180 m,
3 m depth.
April 2015- Jan 201615

Non-destructive sampling approach(Tester et al. 2012, 2014; Tan et al. 2013; Yong et al. 2018)168

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CELL ENUMERATION & SPECIES CHARACTERIZATION
Morphology-based

Molecular-based

Culture establishment

Field specimens

Morphological observationand cell enumeration

17

Five major taxonomic groups in thebenthic harmful dinoflagellateassemblages
CooliaOstreopsis

Fukuyoa
Gambierdiscus
Prorocentrum

Amphidinium

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BHAB spatial distribution

feasibility of theartificial substrate
method as analternative sampling
approach in BHAB
studies.

Yong et al. (2018) Harmful Algae

19

Implication in CFP risk assessment

CFP

Because Rawa Island has not experienced a CFP event, it issuggested that Gambierdiscus abundance <1000 cells/100 cm2
may serve as the lowest threshold, i.e. low risk of CFP.

?

8While regulatory decisions to limit or close fishing are notbased on cell abundances of Gambierdiscus, these dataset
suggests that CFP risk is low when cell abundances are
consistently below <1000 cells/100 cm2.

1103 cells/100 cm235

The data obtained with this method can be used to establish abaseline in assessing the risk of CFP.

Yong et al., 2018; Lee et al., 2020.

20108/7/2021

Reef microhabitats play an importantrole in structuring the benthic harmful
dinoflagellate communities, but there
are few that provide statistically robust
studies with well-defined habitat
characterization.
An underwater photoquadrat survey wasperformed simultaneously at eachsampling point to record the percent
coverage and variety of benthic
substratum and the biotic inhabitants.

REEF SURVEY
21

Underwater
Photoquadrat survey

BENTHIC MICROHABITAT CHARACTERIZATIONnMDS

Image analyses

Multivariate analyses
ImageJ / Coralnet
percent coverage,
variety of benthic substratum2211

8/7/2021

Microalgae-habitat interactions
GOCPA

23

Microhabitat heterogeneity affects the BHAB assemblages
Though the findings of this study also show significant differences in the benthic harmful
dinoflagellate assemblages among various microhabitats as previously reported, they challengesome long-held assumptions concerning the preferences for certain substrate types.

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In contrast, Ostreopsis did not show the same substrate preferences asGambierdiscus. It was found on nearly all substrate types, but maximum
cell abundance was detected in microhabitats with high coral cover, andto a lesser extent, high filamentous algal cover.
Ostreopsis is known as anopportunistic group
adapted to broad ranges ofenvironmental conditions(Tindall and Morton, 1998;
Vila et al., 2001).

25

Degraded reef

2613Study site

8/7/2021

Reefs cover different depths(1 - 25 m).
Total screen samplers
deployed = 234
April 2016 - May 201727

BENTHIC MICROHABITAT CHARACTERIZATION
28

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Depth distributionof BHAB assemblages
Light intensity (mol m-2 s-1 )
00500

1000

1500

2000

Turf algal
cover

Depth (m)51015

Hard coral
cover

Fleshy algal
cover2029

Prorocenrum and Coolia have abroader range of depth distribution,
can be found in deeper waters.
This suggested that, depending on
the substrate suitability andavailability, the variation in BHAB
adaptability to different depth is likely
influence by other driving factors
such as light intensity and exposure
to water disturbance.

30158/7/2021

Physical measurements of the temperature and light
were obtained by deploying data loggers.

Intermonsoon

Southwest monsoon

Intermonsoon

31.8°C*

31.6°C*

31.3°C*Intermonsoon

Northeast monsoon

36
3-5 m~10 moTemperature ( C)34
32

29.8 °C*
29.2 °C*

3028Mar

AprMayJunJulAugSepOctNovDecJan2016

FebMarApr2017

Seasonal variation in water temperature
31Temporal variability
Changes in temperature and associated climatic conditions
profoundly affect the abundance and distribution of species acrossmicrohabitat types.
Gambierdiscus

Dry season

Wet season

32

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CONCLUDING REMARKSThis study highlights the variability ofbenthic substrate types influence thedistribution of BHAB taxa in complex waysthat interact with other environmental
driving factors.
The artificial substrate method coupledwith benthic habitat characterization could
serve as an alternative tool to study in situ
BHABs abundance and distribution.
These datasets could serve as a basis forcomparison and of consideration in BHAB
monitoring strategy in CFP prone areas.

33

Climate changes

Disturbances that alter benthic
substrate type of a coral reef canhave profound effects on thecomposition of
BHAB species present.

Local stresses

Healthycoral reef

CFP vectors
Degradedcoral reef

Disturbance Frequency

Alteration of trophictransfer

HIGH
BHAB species

Reef Recovery
Algal palatability

LOW
HIGH

34

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Climate change and Benthic HABs

Global SST increases of 0.4–1.4 °C by 2055 will
promote growth rates of many BHABs (Testeret al. 2020).
Northward expansion of BHABs and CFPevents.

35

UN IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC,September 2019) was the first IPCC report to directly link HABs to climate change.
The following declarations were included in the Summary for Policy Makers:• Harmful algal blooms display range expansion and increased frequency in coastal areas
since the 1980 in response to both climatic and non-climatic drivers such as increased
riverine nutrients run-off.
• The observed trends in HABs are attributed partly to the effects of ocean warming,
marine heatwaves, oxygen loss, eutrophication and pollution.
• Harmful algal blooms have had negative impacts on food security, tourism, local
economy, and human health.
(Gobler 2021 Harmful Algae)

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Acknowledgements
MESTECC & MOE Research funds

WESTPAC HAB for travel support

Protect

coral reefs
ourprevent C I G U A T E R A

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