An inventory of coral reefs in Langkawi Archipelago, Malaysia

35 Pages·2003·0.3 MB·English

by  Kerstin Edlund

An inventory of coral reefs in
Langkawi Archipelago, Malaysia
– Assessment and impact study of sedimentation
Dagmar Jonsson
Arbetsgruppen för Tropisk Ekologi Minor Field Study 88
Committee of Tropical Ecology
Uppsala University, Sweden
March 2003 Uppsala
An inventory of coral reefs in
Langkawi Archipelago, Malaysia
– Assessment and impact study of sedimentation
Dagmar Jonsson
Undergraduate thesis in Biology
Examensarbete i Biologi, 20p, HT 2002
Department of Animal Ecology, Uppsala University, Sweden
Supervisors: Göran Milbrink, Bo Tallmark, Muhamad Abdul Nasir Salam
Abstract
An inventory study of four coral reefs was performed during December 2001 and January 2002
in Langkawi archipelago and in Pulau Payar Marine Park, Malaysia. To get a general state of
the reefs several parameters were investigated. Using Linear Intercept Transect (LIT) the
amount and distribution of dead coral, living coral and corals covered by sediments, diversity
and amount of rubble were studied. The level of sediments in the water was also estimated by
measuring the turbidity in the water mass. Collected data were analysed with ANOVA,
Kruskal-Wallis Test and Correlation tests. The results show that the area around Langkawi is
highly affected by sedimentation and that the reefs in the area are more disturbed compared to
the reef in Pulau Payar Marine Park. Since the 80’s Langkawi has been expanding as a new
tourist destination and the exploitation of the island has resulted in a major outflow of
sediments into the water. When comparing the three investigated reefs in Langkawi
archipelago, a gradient of disturbance can be seen. The reef in Pulau Rebak Besar is located
closest to exploited areas and is in worst condition with the highest amount of dead corals and
corals covered by sediments. The reef in Pulau Singa Besar is the least disturbed reef and the
one in Teluk Datai is disturbed to a level in between. The reef in Pulau Payar has the highest
amount of living coral of all compared sites and is only slightly affected by sedimentation. It
seems that the coral diversity is not seriously affected by the disturbance. In all studied reefs in
Langkawi similar number and types of genera were found compared to Pulau Payar more
genera were found in the sites in Langkawi archipelago. The low number of genera in Pulau
Payar is probably due to El Niño 1998, when most of the branching coral species bleached and
eventually died. It is obvious that the sedimentation is a serious threat to the coral reefs as well
as the whole marine ecosystem in the Langkawi archipelago. Corals are dying and as a result of
that fish population is decreasing. The beauty of a healthy marine ecosystem, which usually
attracts lots of tourists, is nearly gone. To guarantee further income of fishing and tourism in
the future, the outflow of sediments from the islands must be put to an end.
Foreword
This study is a part of “Vision of a blue environment: the Langkawi Archipelago” which is a
project initiated by the World Wide Fund for Nature in Malaysia. The main issues in this
project involves the marine and coastal environments and the aim is to, with studies and
research, encourage conservation planning and sustainable actions to secure the future for the
natural ecosystems in Langkawi Archipelago.
Table of contents
1. Introduction 4
Impacts on coastal ecosystems in Asia 4
Coral reef ecology 4
Economic values 5
Stress and degradation of coral reefs 5
Aims of the study 5
Previous work in Langkawi 5
2. A general description of the Langkawi Archipelago 6
Geology 6
Climate 6
Population and economy 6
Tourism 6
3. Study areas 7
Teluk Datai 8
Pulau Singa Besar 8
Pulau Rebak Besar 9
Pulau Payar Marine Park 9
4. Field methods 9
Linear Intercept Transect (LIT) 9
Measurements of environmental parameters 10
5. Statistical methods 11
6. Results 11
Substrate cover and biotic factors 11
Living and dead coral 12
Coral families and genera 13
Diversity 16
Sedimentation 17
Turbidity 19
Rubble 20
Water quality measurements 21
7. Discussion 22
Living corals 22
Diversity 22
Sedimentation 23
Turbidity 24
Rubble 24
Relation of coral reef degradation to coral reef fishes 25
Conclusions 25
8. Acknowledgements 26
9. References 27
Appendix I 29
Appendix II 31
1. Introduction
Impacts on coastal ecosystems in Asia
Asia faces as many coastal management problems as other regions of the world: depletion of
coastal fishery resources; reduction in catch; loss of income; degradation of habitat (e.g.
mangroves, seagrasses, and corals) and deteriorating water quality. In addition, coastal
population densities are high and increasing due to migration from inland areas. Southeast Asia
has the highest percentage of human coastal population in the world; 80% of the population
live in coastal areas (Nickerson-Tietze 2000) and exert enormous pressure on the coastal
ecosystems. The level of acceptable exploitation by fisheries has long ago been exceeded, as
well as harvest of mangroves and other types of ecosystems (Lundin & Lindén 1993).
The human population of Asia depends on fish, which is one of the cheapest sources of protein.
In Malaysia 20% of the total animal protein supply comes from fish (FAO 1995). In Asia,
fishing is perhaps the most common use of marine and coastal resources. Capture size depends
on ecosystem health, and nowhere is this felt more than in small scale fishing communities
(Nickerson-Tietze 2000).
There is considerable evidence for a clear correlation between the productivity of tropical
coastal ecosystems (particularly in mangrove forests, seagrass beds and coral reefs), and the
productivity of the fisheries (Rogers 1990). The consequence of the degradation of mangroves
and coral reefs will inevitably result in a corresponding decrease in the fish stocks and a drop in
the catches. In many countries in Southeast Asia, fish catches have actually been dropping over
the last decade (Lundin & Lindén 1993).
In Southeast Asia where approximately 30% of the world’s coral reefs are found, about 60% of
the reefs are destroyed or are on the verge of destruction (Wilkinson et al. 1993). The
remaining reefs are also threatened and it can be predicted that most of the reefs in the region
will be eradicated within the next 40 years. The major causes for the destruction of the reefs in
Southeast Asia are directly or indirectly induced by humans: organic and inorganic pollution,
sedimentation and overexploitation (Lundin & Lindén 1993). Sedimentation is associated with
the construction of hotels, condominiums, runways, roads and military installations and beach
replenishment (Jaap 1984 and Dahl 1985). Dredging near coral reefs and accelerated runoff of
eroded soils increase turbidity, thereby cutting off light available for photosynthesis, as well as
increasing sediment load on corals. Sediments, which settle down on coral colonies and are
suspended in the water column, have sub-lethal and lethal effects (Rogers 1990).
Coral reef ecology
Coral reefs are unique among high-diversity and high-productivity marine communities
(Richmond 1993). They are found in areas where the water is warm (>20 oC) and clear, often in
shallow water to a depth of about 60 meters. The depth at which coral reefs can form is limited
by the depth to which sunlight can penetrate to power the vital process of photosynthesis
(Karleskint 1998). Through evolution corals have become adapted to nutrient poor
environments (Richmond 1993) and coral reefs develop in water that contains minimal amounts
of plankton. This is not surprising, since corals require clear water so that there will be enough
light to support their photosynthetic symbiosis.
The key to the high productivity of coral reefs is the symbiotic relationship between the coral
polyps and the photosynthetic zooxanthellae. The zooxanthellae provide the corals with
nutrients essential for reef building and oxygen produced by the photosynthesis. In turn the
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zooxanthellae absorb amino acids, sugars, and other organic compounds directly from the
host’s tissues. Not only do corals provide a basis for the reef food web; their colonies also
provide shelter for a great number of resident organisms (Karleskint 1998). Killing or removing
the corals indirectly affect the biological environment by reducing refuges for mobile animals,
increasing open space on which sessile species settle, altering the food supply of consumers or
concentrating the attacks of predators on the survivors (Connell 1997). Probably 30-40% of all
fish species on earth are found on coral reefs (Stiling 1999).
Economic values
In addition to the biological values, the coral reefs hold a lot of economic and socio-economic
values. They support the fisheries, draw tourists, afford recreational opportunities and produce
a diversity of natural products, which have proven to be of biomedical importance. The coral
reefs also produce islands and protect the shore by buffering waves that would otherwise cause
extensive coastal erosion. The protection is especially evident during typhoons and tropical
storms (Richmond 1993).
Stress and degradation of coral reefs
Coral reef organisms are usually very sensitive to environmental conditions, exhibiting a
relatively narrow range of tolerances to environmental stress. Stress is a physiological
condition, which results from adverse or excessive environmental factors and in corals can be
measured by decreasing growth rates, metabolic and biochemical changes. Small changes in
environmental quality can affect critical biological processes, such as reproduction and
recruitment (Richmond 1993). Numerous studies have suggested a variety of indicators of the
status of a reef. The most commonly used indicator is the abundance of various key organisms
(e.g. a lowered abundance of corals or coral fish or too much algae), which might indicate that
a coral reef has been degraded. Population structure or size-frequencies and species
composition (e.g. species richness, diversity, and evenness) may also provide clues of a reef
under stress. In addition, physical or chemical variables (e.g. salinity, turbidity, nutrients) are
often measured to describe environmental conditions on coral reefs, although these on their
own provide no direct evidence of any biologically significant impact (Ginsberg 1993, Hughes
& Connell 1999).
Aims of the study
The marine ecosystem in Langkawi Archipelago is suspected to be seriously affected by the
sedimentation in the area and this study was made to assess the impact of the sedimentation.
The aim of this study was: (1) to investigate the state of three coral reefs in the Langkawi
Archipelago and one in Pulau Payar Marine Park by a study of the amount of dead and living
coral and the amount of rubble and the number of genera, (2) to investigate the impact of the
sedimentation and the turbidity in the water column and make a comparison of the impact of
sedimentation between the protected reef in Pulau Payar Marine Park and the reefs in the
Langkawi Archipelago.
Previous work in Langkawi
There are few scientific studies which have been made on the marine environment in Langkawi
in contrast to the well studied Pulau Payar Marine Park 30 km to the south. A biological
assessment of the marine resources of the Langkawi Archipelago was made by Hendry and
McWilliams (2001). This study covers the coral reef habitats and coral fish populations and
assesses the threats to the marine coastal resources. A study has also been made of the coral
reef and the water quality in Teluk Datai on the north coast (Zulfigar 1996). Several reports
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concerning the state of the coral reefs in Pulau Payar Marine Park, the impact of tourism and
the management of the park have been published:
1. The Pulau Payar reef system (Rashid 1980)
2. Coral reef survey of Pulau Payar/Segantang group of islands, Malaysia (De Silva &
3. Abdul Rahaman 1982)
4. Carrying capacity assessment of Pulau Payar Marine Park, Malaysia (Lim 1998)
2. A general description of the Langkawi Archipelago
Geology
The Langkawi Archipelago (6o 18’ N, 099o 47’ E) is located in the Andaman Sea, 30 km west
of the northern end of Peninsular Malaysia at the border between Malaysia and Thailand (see
Fig.1.). The archipelago consists of 104 islands and the largest and most exploited island is
Langkawi Island (478,5 km2). The bedrock of the islands is a mixture of limestone and
sandstone, and the vegetation of the islands is dominated by rainforest. The coastal areas
consist of flat, alluvial plains, limestone ridges and mangrove forests (www.Langkawi-
online.com).
Climate
Langkawi has a tropical monsoon climate with a high annual temperature (varying between
24oC and 33oC) with an annual average rainfall of 2500 mm. The rainy season ranges between
April and October and the dry season begins in November and lasts until March
(www.Langkawi.insights.com).
Population and economy
Only four of the 104 islands are inhabited – Pulau Langkawi, Pulau Tuba, Pulau Rebak and
Pulau Dayang Bunting with a total human population of 54 000 (www.Langkawi-online.com).
About 35 per cent of the total land area in Langkawi is used for agriculture – rubber 40 percent,
rice 30 percent, mixed crops 20 percent and coconut plantations 10 percent (www.Langkawi.
insights.com). An agriculture-based economy based on rice and rubber cultivation and fisheries
is being overtaken by a tourism economy (www.Langkawi-online.com).
Tourism
In 1987 the Federal Government gave the Langkawi Island a duty-free status, which has turned
Langkawi into a major tourist destination (www.mylangkawi.com). Hundreds of thousands of
Malaysian and foreign tourists visit the archipelago each year.
The majority of the hotels are located on the west coast, along the Pantai Chenang and Pantai
Tengah. Kuah is the main urban center of Langkawi and contains many hotels as well as the
main ferry terminal. The north coast is relatively undeveloped except for the three hotels
catering for the upper end of the tourist market. The east coast is also mostly undeveloped,
bordered with mangrove forests. Tourism activities occur all over the archipelago, including
chartered fishing boats in the north, mangrove tours in the east, island tours in the south and
beach based water sports in the west (Hendry & McWilliams 2001).
Several tour operators on Langkawi are taking lots of tourists on day trips to Pulau Payar. Pulau
Payar was originally established as a “Fisheries Protected Area” in 1987 and subsequently as a
marine park in 1994 aiming to protect important marine resources including coral reefs, which
contribute to biodiversity and fisheries production. The Marine Park lies about 35 km off the
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western coast of Peninsular Malaysia, and is located between the Pulau Pinang in the south and
the Langkawi Islands in the north. 68 000 km2 of marine waters and the four islands Pulau
Payar, Pulau Kaca, Pulau Lembu and Pulau Segantang lie within the boundaries of the park
(Nickerson-Tietze 2000). The establishing of the marine park changed the main use of the
waters of Pulau Payar from fishing to tourism. Today fishing is prohibited within the park (De
Silva and Ridzwan 1982). Swimming, snorkelling and SCUBA diving are permitted. Park
numbers increased from 1373 visitors in 1988 to 90 307 in 1996 (Nickerson Tietze 2000). The
expansion of the Pulau Payar Marine Park as a tourist destination is attributed largely to the
rapid development of the tourism sector of Pulau Langkawi, which is today the major tourist
centre of the northern region of Peninsular Malaysia (Lim 1998).
Figure 1. Map of Peninsular Malaysia showing the location of Langkawi
Archipelago and Pulau Payar Marine Park.
3. Study areas
To get a general view of the coral reefs in the Langkawi Archipelago, different reefs were
scanned through snorkelling. Two characteristics were important for making the choice of
study sites; 1) the reefs had to be large enough for the transects and 2) the corals had to be
fairly evenly distributed to make data calculations possible. Test transect were done by both
observers to standardise observations.
Four reefs with different amounts of disturbance were studied between December 13th, 2001
and January 21st, 2002. Three of them are located in the Langkawi Archipelago; close to the
beach of Teluk Datai and just outside the islands Pulau Singa Besar and Pulau Rebak Besar and
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the fourth reef is located in Pulau Payar, the marine park south of the Langkawi Archipelago
(Fig.2).
Figure 2. Map of the Langkawi Archipelago and Pulau Payar Marine Park. The black dots
mark the study sites in Pulau Rebak Besar, Teluk Datai, Pulau Singa Besar and Pulau Payar,
respectively.
Teluk Datai
Teluk Datai is a bay in the northern part of Pulau Langkawi that opens towards the north. The
reef, which is approximately 600 metres long and 100 metres wide, is situated in the eastern
part of the bay near a small island, Anak Pulau. Two streams flow into in the bay and along
these streams the vegetation consists of mangrove. The rest of the vegetation around the bay is
rainforest.
There are several kinds of human activities on and around the reef. In the late eighties two
hotels were built in the bay, The Datai and the Andaman. Hotel guests are snorkelling,
kayaking and sailing in the area but these activities are limited because only hotel guests have
access to the beach. Sailing boats are anchoring on and close to the reef. Smaller fishing boats
conduct the fishing in the area and some remains of fishing gear such as nets and ropes can be
found on the reef, especially on the outer part. In the strait outside the bay there is some traffic
with large ships going to Teluk Ewa, a bay where a cement factory is located.
East of the bay there is a golf course from which fertilizers and sediment are probably leaking
into the water but the amounts flowing into Teluk Datai are not known.
Pulau Singa Besar
Pulau Singa Besar is an island in the southern part of the archipelago. The reef is situated in a
bay, which faces towards the southeast in the southern part of the island. The vegetation around
the bay consists mainly of rainforest.
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