Impacts of coral bleaching, recovery and management in
Thailand
Abstract. Severe mass coral bleaching events occurred on most reef sites in Thailand in 2010. Bleaching in the
Andaman Sea was more severe and extensive than in the Gulf of Thailand. Several meetings, seminars and
conferences were organized by government agencies, NGOs and universities for gathering information on coral
bleaching impacts, recovery trends and management. A list of recommendations for coral reef management in
Thailand was provided. The important issues include: preventing coral damages from snorkeling in the shallow
reefs, sediment load from coastal development, wastewater discharge from boats and land-based activities into
coral reefs, temporary closure of diving sites, establish new diving sites, conducting research and monitoring for
coral conservation and restoration, informing people and tourists concerning status of coral bleaching, providing
sufficient man-power and budget to relevant government agencies, establishing effective networks of
universities, government agencies, province offices, local administration offices, NGOs, private companies, and
conservation groups. It is necessary to have effective mechanisms for project implementation under Thailand’s
national coral reef management plan. A list of research needed towards adaptation to coral bleaching was also
provided by relevant experts and organizations. Development of young researchers and raising public
awareness are urgently required for coral reef conservation in Thailand in order to manage the pressures and move
societies to a sustainable pathway.
Introduction
Coral bleaching is the most severe threat posed by
climate change to coral reefs in Thailand. Recently,
the severe mass coral bleaching events in 2010
occurred on most reef sites in Thailand. Bleaching in
the Andaman Sea was more severe and extensive than
in the Gulf of Thailand (Yeemin et al. 2010). It is
predicted to increase in frequency and severity in this
century (Hughes et al. 2003; Hoegh-Guldberg et al.
2007; Burke et al. 2011; Hoegh-Guldberg 2011).
Coral recovery from major disturbances, such as the
severe coral bleaching event in 1998, was
documented in some locations (Yeemin et al.
2009). However the coral recovery capacity is likely
to diminish in some locations as disturbance
frequencies increase. Consequently, the risk of coral
bleaching each summer must be viewed in integration,
because the antecedent impacts from previous events
may render corals more susceptible to bleaching and
disease. Both function as structuring forces shaping
future condition of coral reef ecosystem (Great Barrier
Reef Marine Park Authority 2010).
It is well documented that coral reef degradation may
lead to socio-economic losses because of impacts to
coastal fisheries, tourisms and multiple ecosystem
services (Cesar 2000). The socio-economic losses
that result from severe coral bleaching events were
reported (Bunce and Pomeroy 2003). The extent to
which severe mass coral bleaching affects society is
determined by several variables, including the extent to
which coral bleaching leads to coral mortality. There
are varied uses of coral reefs in which coastal
communities have been impacted. It is important to
determine the flexibility of coastal communities to
shift their dependence on coral reefs when reef
degradation occurs (Marshall and Schuttenberg
2006). The future condition of coral reefs will be
mainly influenced by the rate and extent of sea
temperature increases and the resilience of coral reefecosystem (West and Salm 2003; Buddemeier et al.
2004).
Most coral reef managers realize that it is very important
to consider the cumulative impacts of simultaneous
threats to coral reefs. In future the coral bleaching
phenomena is inevitable and coral reef managers
have the responsibility to monitor, assess and respond
to the ecological and socio-economic impacts of coral
bleaching.
Material and Methods
To provide a strategy for coral reef management in
Thailand, Department of Marine and Coastal Resources,
Department of National Parks, Plant and Wildlife, a
network of Thai universities, For Sea Foundation, NGOs
and private companies began the development of the
coral reef management strategy under coral bleaching
crisis in June 2010. A review of physical
oceanography data, coral reef ecology, watershed
ecosystem, coastal zone management and coral reef
management plans in Thailand and other countries was
conducted. Several meetings, seminars workshops
and conferences on coral reef related issues, especially
coral bleaching impacts, recovery trends and
management were reviewed and analyzed (Fig. 1).
Results
Sea surface temperatures anomalies of between 30-
34°C were recorded during March-June 2010 in the
Andaman Sea and the Gulf of Thailand. The
Department of Marine and Coastal Resources, in
collaboration with a network of Thai universities
and NGOs conducted several reef surveys and
reported widespread and severe coral bleaching
of over 80% at several reef sites. Coral bleaching
in the Andaman Sea was more severe and
extensive than in the Gulf of Thailand, with the
inner Gulf of Thailand exhibiting the lowest
bleaching impact. The most susceptible coral taxa
were Acropora spp. and Pocillopora spp. Coral
mortality following the bleaching event is
estimated at about 50 – 60% within the Andaman
Sea, and about 30 – 40% within the Gulf of
Thailand. Some coral species, especially Porites
showed good recovery. It is estimated that the 2010
bleaching event is similar in extent but with
greater severity than the 1998 bleaching event
within the Gulf of Thailand, but greater in extent
and severity within the Andaman Sea.
In the Andaman Sea, reefs on the eastern coast
of the islands showed greater impact than reefs
on the western coast, which are subjected to
internal waves and generally stronger wave action.
Within turbid areas with high water flow, coral
colonies showed resistance to bleaching. It is
possible that within these areas, reduced light
penetration contributed to the overall reduction in
the combined temperature/light stressors that
induced bleaching. Among hard coral species, there
was a mixed response to bleaching, with Galaxea
sp., Diploastrea heliopora, Heliopora coerulea
and free-living fungiids showing greatest resistance
to bleaching. In addition to hard corals, other
zooxanthellate taxa including soft corals, zoanthids
and giant clams were also bleached (Tun et al.
2010; Yeemin 2010). A GIS database and map of
coral condition in Thailand was developed. It shows
coral reef status before and following the 2010 mass
bleaching event for each reef site together with
information on bleaching severity, coral mortality
rate and change in live coral cover (Fig. 2).