A report is made of the first incidence occurring of paralytic shellfish poisoning in Thailand in May 1983, following an extensive bloom of Trichodesmium erythraeum. Investigations undertaken regarding the source of the toxicity are outlined

Sudara, Suraphol

Tamiyavanich, Suthichai

Wisessang, Suchana

Aquatic Commons

Red Tide and Paralytic Shellfish Poisoning Phenomena 
in Thailand
Suraphol Sudara, Suthichai Tamiyavanich and Suchana Wisessang
Department o f  Marine Science, Chulalongkorn University, Bangkok, Thailand
Introduction
Red tide seems to be a seasonal phenomenon 
that occurs from the end of January to August. This 
phenomenon, which occurs particularly in the inner 
part of the Gulf of Thailand where four major 
rivers, Bang Pakong, Chao Phraya, Tha Chin, and 
Mae Klong open into the sea, has been observed 
during the past 30 years.
In 1957, Charenpol reported on its impact on 
the fisheries industry. Since then, the red- 
tide phenomenon has been observed more 
frequently. Ceratium, Rhizosolenia, Chaetoceros, 
Skeletonema, Nitzchia, Thalassionema, Pleuro­
sigma, and Trichodesmium were recorded as the 
major species of phytoplankton usually found 
during the algal bloom (Paphavasit and 
Tamiyavanich 1984). Certain species were reported 
to be associated with estuarine areas of the Chao 
Phraya and Bang Pakong rivers. They included 
Bacteriastrum, Triceratium, Coscinodiscus, Cyclo­
tella, Hemidiscus, Thalassiotrix, and Surirella.
Between 12 and 21 February 1981, an extensive 
red tide was observed at the Tha Chin estuary. 
Chernbamroong and Tharnbupha (1981), from the 
Department of Fisheries, reported that the bloom 
was dominated by the dinoflagellates Noctiluca 
miliaris and Ceratium furca.
Suvapepun (1982) reported that during the 
blooms in 1981-1982 the colour of the red tide, 
which was yellowish-green, was from Tricho­
desmium, whereas the gelatinous white colour was 
from the combination of Coscinodiscus, 
Rhizosolenia, and Hemidiscus, which also gave rise 
to a strong fishy odour. Noctiluca, the bloom of 
which is found seasonally along the coast during 
February and March, caused the green colour.
Suvapepun et al. (1984) stated that 
Trichodesmium erythraeum  was the major species 
of algal bloom in 1983 along the east coast of the
inner gulf from Chonburi to Chantaburi; it lasted 
from May to June. When washed ashore, it resulted 
in a very bad smell. This bloom caused extensive 
damage to fish farms in Rayong and Chonburi. At 
the same time, Trichodesmium erythraeum  also 
bloomed along the west coast of the inner gulf from 
the mouth of the Mae Klong River to Petchaburi.
A Case Study o f Shellfish Toxicity 
in Thailand
From 12-16 May 1983, the same time when an 
extensive bloom of Trichodesmium erythraeum  was 
reported in the gulf, a case of shellfish poisoning 
was reported at Pranburi, Prachuabkirikan 
Province on the west coast of the gulf. When the 
green mussel, Perna viridis, collected locally from 
the natural population within Pranburi River, was 
consumed by the local people, they showed 
symptoms of paralytic shellfish poisoning (PSP), 
such as numbness of the mouth, hands, and feet; 
disruption of breathing; and vomitting. Thirty-four 
people were rushed to the hospital, fourteen were 
hospitalized, and a 3-year old girl died 
(Subcommittee on the Water Quality and the 
Quality of Living Resources in Thai Waters 1983).
Investigations of that case were carried out by 
various groups, such as the Department of 
Fisheries, Department of Public Health, and 
Department of Marine Science of Chulalongkorn 
University. During preliminary investigations, 
phytoplankton samples were collected along with 
environmental parameters and it was found that the 
algal bloom consisted of a combination of various 
species of diatoms, dinoflagellates, and 
Cyanobacteria. Dinoflagellates of several species 
were found to be more abundant than usual. 
Protoperidinium quinquecorne, Prorocentrum 
micans, two species of Peridinium, and three species 
of Gonyaulax were reported, with maximum
90
densities of Protoperidinium quinquecorne and 
Cyanobacteria. The water in Pranburi River had a 
high BOD value, with the maximum being 5.8 
mg/ L (Subcommittee on the Water Quality and the 
Quality of Living Resources in Thai Water 1983). 
Details of phytoplankton composition and 
environmental quality can be found in Suvapepun 
(1984).
The Study of Toxicity
The green mussel was collected from the area 
and it was found that the concentration of water- 
soluble paralytic shellfish poison was about 100 
times higher than the permissible standard of 4 
MU/g as reported by the Environmental Health 
Division, Department of Health. Saitanu and 
Tamiyavanich (1984) reported the maximum 
toxicity of PSP as 12057 µg/100 g, which was quite 
high.
Investigation of the Source of Toxicity
The Department of Marine Science, 
Chulalongkorn University, became involved in the 
investigation immediately after the Pranburi 
incident was reported. After more than 1 year of 
investigation, and in cooperation of Japanese 
experts Drs Yasuwo Fukuyo and Takashi 
Ishimaru, from the University of Tokyo, and Dr. 
Masaaki Kodama, from Kitasato University, the 
results point out that this was truly a case of PSP. 
The study of the toxin from the green mussels 
collected showed that it was a gonyautoxin. 
Investigations are now going on to confirm whether 
Protogonyaulax sp., which was found although not 
in very high concentrations during the incident, 
could be the source of this biotoxin; and the specific 
name of this organism is being looked into. It is 
suspected to be Protogonyaulax sp., which occurs 
naturally in the inner gulf in low concentrations, 
because P. tamarensis was reported to cause toxicity 
elsewhere. The physical appearance of the 
Protogonyaulax sp. collected is very similar to P. 
tamarensis, although there are some structural 
differences and P. tamarensis is a cold-water species. 
As of now, pure cultures of Protogonyaulax sp. are 
being studied.
It should also to be noted that Pranburi, where 
this case of PSP was reported, it not a location for 
mussel culture. Local people gather naturally grown 
mussels for their own consumption. Therefore, this 
case should not be confused with commercially 
farmed mussels in the market.
It should be mentioned that, along with studies 
on PSP, investigations are also under way on 
diarrhoeal shellfish poisoning (DSP). The organism 
believed to be the source of DSP, Dinophysis 
caudata, is also found in the inner gulf.
This paper has discussed the first occurence of 
biotoxin in relation to algal blooms in Thailand. 
However, Piyakarnchana and Tamiyavanich (1979) 
have emphasised that the red-tide phenomenon 
could become more serious because of increasing 
pollution from rivers. Because mariculture has 
become widespread along estuarine areas of the 
inner gulf, it is important that more attention be 
given to this problem.
Charernpol, S. 1957. Preliminary study of discolouration 
of sea water in the Gulf of Thailand. IXth Pacific 
Science Congress, Bangkok, Thailand, 18-30 
November 1957, 8 p.
Chernbamroong, S. and Tharnbupha, C. 1981. Water 
pollution surveys at the Ta Chin and Mae Klong 
estuaries. Marine Fisheries Laboratory Report No. 
24/1. Marine Fisheries Division, Bangkok, Thailand, 
23 p.
Paphavasit, N. and Tamiyavanich, S. 1984. Status of the 
environmental quality in the inner section of the Gulf 
of Thailand. Regional Technical Workshop on the 
Protection of the Marine Environment and Related 
Ecosystem, Bangkok, Thailand.
Piyakarnchana, T. and Tamiyavanich, S. 1979. Increase 
in red water phenomena in the upper portion in the 
Gulf of Thailand. Journal of Aquatic Animal 
Diseases, 2(4), 207-215.
Saitanu, K. and Tamiyavanich, S. 1984. Paralytic 
shellfish poison in Pracnuap Kiri Khan Province and 
west coast of the upper Gulf of Thailand. 3rd Seminar 
on the Water Quality and the Quality of Living 
Resources in Thai Waters, Bangkok, Thailand. In 
press.
Suvapepun, S. 1982. Red tide in the coastal water of the 
Gulf of Thailand. Fisheries Gazette, 25(6), 581-593.
1984. Shellfish poisoning in association with 
the occurrence of potentially toxic dinoflagellates in 
the Gulf of Thailand. This volume.
Suvapepun, S., Chernbamuroong, S., and Wang­
charernporn, W. 1984. The impact of red tide on 
coastal fisheries. Paper presented at the 22nd 
Conference, Fisheries Section, Kasetsart University, 
Bangkok, Thailand.
Tamiyavanich, S. 1984. Changes in phytoplankton 
composition and the cause of paralytic shellfish 
poisoning at Pranburi. 3rd Seminar on the Water 
Quality and the Quality of Living Resources in Thai 
Waters, Bangkok, Thailand. In press.
Subcommittee on the Water Quality and the Quality of 
Living Resources in Thai Waters. 1983. Preliminary 
report on the paralytic shellfish poisoning case at 
Pranburi, Prachuabkirikhan Province. Journal of 
Aquatic Animal Diseases, 6(2), 93-102.
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Red tide and paralytic shellfish poisoning phenomena in Thailand

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Red tide and paralytic shellfish poisoning phenomena in Thailand

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