RED
TIDE MANAGEMENT IN BRUNEI DARUSSALAM
Introduction
Red
Tide phenomenon is associated with the change in water coloration from
normal to a reddish or brownish color due to a sudden bloom of planktonic
algae. Red Tide phenomenon was first recorded in the coastal waters of
Brunei Darussalam in 1976. Since then the coastal waters of Brunei
Darussalam experienced sporadic bloom. The culprit was identified as Pyrodinium
bahamense var. compressum. The subsequent red tide events
were repeated in 1980 and the last occurrence was in 1988 caused by the
same organism.
HISTORY
OF RED TIDE OCCURRENCES
The
1976 Red Tide Occurrence
The
occurrence was discovered almost by chance by Fisheries Department
biologists who were conducting routine scientific work on 11 March 1976.
The water and plankton samples were collected and examined. Initially, the
culprit was thought as Gonyaulax but eventually identified and
confirmed as Pyrodinium bahamense. The red tide event overwhelmed
the entire country which had, till then no experience with red tides.
Fortunately, no fatalities were reported, although five patients were
hospitalised after consuming mackerels (Rastrelliger sp.) and Scads
(Selar sp.)
The
1980 Red Tide Occurrence
A
second outbreak occurred in early 1980. The outbreak was initially
reported in Brunei Bay and the information was obtained from various
sources on 28 April 1980. The bloom was confirmed as Pyrodinium
bahamense var. compressum. The blooms were more diffused and
not visible on most occassions. There was no incident of Paralytic
Shellfish Poisoning as a resultt of the cooperation of various agencies
such as Navy, Air Force and commercial airlines and the early warnings
issued and precautions taken based on the previous experience. In
addition, there was the establishment for a regular monitoring of red tide
outbreak by the Fisheries Department.
The
1988 Red Tide Occurrence
After
the 1980 incident, red tide occurrence subsided. However, the department
was on constant alert due to blooms occurring in neighboring Sabah,
Malaysia between July 1983 and December 1986. Red tide reappeared in
Brunei Darussalam in December 1988 when 40 cats were treated and seven
perished at the Government Veterinary Clinic after consuming whole guts,
gills etc of Clupeid
fish, Sardinella sp. The causative organisms was similar to that
causing red tide incidents in 1976 and 1980.
A
ban was enforced on the importation of planktivorous fish and extended to
the importation of molluscan shellfish. Unlike previous incidents, no
visible blooms are observed despite the high concentration of PSP level in
the planktivorous fish and molluscan shellfish.
Red
tide-causing organisms are potentially lethal and may lead to death if
affected fish or shellfish are consumed by humans. The organism contains
toxins which can cause Paralytic Shellfish Poisoning/Paralytic Fish
Poisoning (PSP/PFP) and may lead eventually to death. Thus, during red
tide occurrences, affected fish and shellfish are normally banned from
being harvested. Luckily, no human fatalities were recorded during the
local red tide events or as a result of eating contaminated fish from
neighbouring countries.
During
red tide occurences, small planktivorous
fish and molluscan shellfish are known to be affected. Large demersal
fish, crustaceans and other molluscs such as squids are not affected.
Role
of the Department of Fisheries
Since
the first occurrence in 1976, various impacts had been reported in terms
of human illness and economic losses. The losses were due to the closures
of shellfish farms and the ban in harvesting, importing and selling of
shellfish from red tide affected areas. However, various steps had been
taken by the relevant authorities to mitigate the negative impacts.
Although
Brunei Darussalam had its last experience of red tide in 1988, the country
had developed several regular monitoring programmes to monitor the
impending red tide occurrences in the coastal waters and established
regular contacts with its neighbouring countries for red tide information.
a)
Management of Red Tide at National Level
Water
and Plankton Samplings
The
Fisheries Department conducts water and plankton samplings as a
routine activity to look out for red tide occurrence. The monitoring is
done frequently at every fortnight during a non-red tide event and
increases to once every two days during red tide.
Sampling
stations for the monitoring activity have been pre identified based on the
earlier occurrence of the red tide events. The stations are as in Fig.
1. A total of ten stations are monitored of which five are inshore
within the Brunei Bay and the other five offshore.
Water
samples will be collected and analysed in the red tide laboratory for the
absence or presence of red tide organisms. However, other water quality
parameters such as temperature, salinity, dissolved oxygen and visibility
are measured in-situ.
The
presence of a high density of
red tide organisms indicate the waters are experiencing a red tide
occurrence.
Fish
Stomach Analysis
Beside
routine water and plankton samplings, fish sold in the wet markets are
monitored frequently. The fish are collected randomly for analysis of
stomach content and gills. The analysis is done in two steps: qualitative analysis to
determine absence or presence of red tide organisms, and quantitative
analysis to measure the level of toxins.
The
monitoring of fish samples is done to ensure fish sold to the public is
not contaminated with red tide organisms.
Both
fish stomach analysis and water
and plankton samplings are done regularly in a routine manner. These
activities are the early warning system established by the department to
safeguard the public against red tide events. In the case of a red tide
event occurring either
locally or in neighbouring countries, the Department of Fisheries will
activate the National Red Tide Action Plan.
b)
Management of Red Tide at Regional Level
Because
of its huge dependence on imported fish from neighbouring countries, the
Department has to be aware on the red tide situation in those countries.
Regular contacts are made with the relevant authority. Within ASEAN,
Brunei Darussalam is a member of a red tide information network.
Brunei
Darussalam has also set up a communication network with the Department of
Fisheries in Sabah, Malaysia since the occurrence of red tide locally.
This communication network has been regular in exchanging information on
red tide events in respective countries.
c)
National Red Tide Action Plan
In
addition to regular monitoring and surveillance, a National Red Tide
Action Plan (NRTAP) was developed in 1992. The NRTAP is
executed by a team of officers from Fisheries Department (Chairman),
Health Services Department, Municipal Board and the District Office. The
team is aptly called the National
Red Tide Response Team (NRTRT).
The
objectives of the NRTAP is to provide timely and adequate responses to
safeguard public health and to minimise economic losses during red tide
occurrences. It establishes the procedures and responsibilities so that
the response time can be reduce to a minimum during red tide occurrences
and aims to :
- Safeguard
public health against Paralytic Shellfish Poisoning (PSP);
- Provide
advance warning of impending red tides by regular monitoring;
- Reduce
the response time in case of red tide occurrences;
- Provide
accurate information to the public;
- Build
up public confidence in the ability of the authorities to mitigate the
effects of red tide.
The
procedures of the NRTAP in case of red tide occurrence involve four phases
as follows :
Any
information on actual or suspected red tides should be immediately
conveyed to the Chairman/Deputy Chairman of the NRTRT.
The Chairman/Deputy Chairman will alert all other members of the NRTRT.
The following action will then be carried out:
Phase
I - Confirmation Of Red Tide Occurrence
- The
Quality Control Section of the Department of Fisheries will proceed
immediately to confirm the report and provide feedback to the NRTRT;
- Reports
of water discoloration in the coastal waters outside the range of
small boats to be investigated by helicopter;
- Detection
of unusual numbers of Pyrodinium in vertical plankton haul
samples or in the gut contents of planktivorous fish to be followed by
immediate PSP toxin assays;
- In
the case of suspected Paralytic Shellfish Poisoning (PSP); where
possible, samples of cooked/uncooked food and if traceable, samples
from market outlet of suspected fish/shellfish should be tested for
the presence of PSP toxins;
- Although
PSP toxin level of 80 ug/100 gm of fish flesh is generally accepted as
hazardous to human health, the presence of detectable levels of PSP
toxins in fish/shellfish will be taken as sufficient evidence of an
occurrence of red tide;
- The
Department of Health Services will alert all hospitals and clinics to
be on the look out for patients with possible symptoms and
Paralytic Shellfish Poisoning;
The
Royal Brunei Air Force, Royal Brunei Airlines, the Marine Department,
Brunei Shell Company Sdn. Bhd. are to be requested to report any unusual
water discoloration in the coastal waters.
Phase
II - Steps to be Taken on Confirmation of a Red Tide Occurrence
The
procedures will depend on the extent and severity of the red tide incident
and whether it is in Brunei Darussalam or in neighbouring countries.
- Warning
of prevailing red tides and safeguards that need to be taken, such as
not consuming affected fish and shellfish, is to be given to the
public through radio, television, newspapers, posters and notice
boards;
- The
Department of Fisheries will issue orders banning the
harvesting/importation of molluscan shellfish and if necessary of
planktivorous fish and other affected organisms;
- The
Department of Fisheries, the Municipal Board and the District Office
are to keep surveillance over markets and other sales outlets to see
that no banned fish/molluscan shellfish are sold;
- The
Quality Control Section of the Department of Fisheries is to reduce
the interval of monitoring for :
- Red
tide sampling to every alternate days instead of the usual once a
fortnight;
- Fish
gill and gut analyses every day instead of once in a week;
- Paralytic
Shellfish Poisoning (PSP) toxin analysis every once a week or when
necessary;
- Increase
monitoring stations to cover Tutong, Belait and Temburong Districts;
- The
Quality Control Section to maintain close contact with the Fisheries
Department of the East Malaysian States of Sabah and Sarawak with
respect to the red tide situation.
Phase
III - End of a Red Tide Occurrence
Recurrent
negative results for PSP toxins in test shellfish for at least THREE
MONTHS together with only the occasional occurrence of a few
cells of Pyrodinium bahamense var. compressum in plankton
haul samples over the same period of time can be taken to signal the end
of red tide occurrence. The following action are to be taken :
- The
NRTRT should make a public announcement that the red tide alert is
lifted. The same media utilised to warn the public of a red tide
occurrence should be used for the purpose;
- All
posters and boards put up to warn the public regarding a red tide
occurrence should be removed unless they were put up for the purposes
of public education or awareness on red tides. Particular attention
should be given to boards banning the harvesting of shellfish from
specific locations;
- The
Quality Control Section to revert back to normal monitoring and
surveillance procedures.
Phase
IV - Review of the Red Tide Action Plan
A
review of the National Red Tide Action Plan is necessary after the
occurrence of a red tide incident to strengthen areas of weakness or
updating of contact numbers. Further, at least an annual review needs to
be made to maintain the accuracy of the following :
- Emergency
contact addresses;
- Telephone
numbers;
- Updating
of detection techniques for PSP toxins and the red tide organisms
would be necessary because of the rapid progress being made in these
areas.
