The Impact of Coral Degradation on Coastal Communities in Southeast Asia

Viewpoints published by Ballard Brief are not necessarily endorsed by BYU or The Church of Jesus Christ of Latter-day Saints.

Summary+

Coral reefs across the globe are in decline, but reefs in Southeast Asia are among some of the most threatened in the world. Climate change, triggered by fossil fuel emissions, raises sea water temperatures and lowers the ocean’s pH, contributing to coral bleaching and inhibiting coral growth. Local threats also particularly affect reefs in Southeast Asia, such as destructive fishing techniques and marine and inland sources of pollution. Coastal communities in Southeast Asia are especially vulnerable to the degradation of coral reefs due to economic reliance on these reefs and their proximity to them. Declining coral reefs can damage the economy and the livelihoods of individuals dependent on reef fisheries and reef tourism. It also negates the coastline protection that coral reefs offer. Southeast Asian governments are working to create protected areas for these coral reefs, and other organizations are studying ways to rehabilitate degraded corals. Still, more comprehensive research is needed to determine their success now and in the future.

Key Takeaways+

• More people live near coral reefs in Southeast Asia than in any other region in the world.
• Fisheries in Southeast Asia bring in an estimated $2.4 billion every year.
• Mass coral bleaching events due to climate change once occurred only every 25–30 years but now occur an average of every six years.
• Blast fishing and poison fishing threaten 56% of the coral reefs in Southeast Asia.
• Coral reef tourism brings in $5.8 billion and over 35 million visitors annually.
• For every square kilometer of healthy coral reef, Southeast Asia saves as much as the equivalent of $110,000 every year through coastal protection.
• Approximately 14% of Marine Protected Areas in Southeast Asia are rated as being effectively managed.

Key Terms+

Coral Polyps—The individual coral animals that grow together to make a larger coral colony.¹

Coral Substrate—The material that coral polypsThe individual coral animals that grow together to make a larger coral colony.¹. attach and grow on, such as live coral, dead coral, rock, rubble, and sand.²

Coral Triangle—An extremely diverse region of the ocean, spanning Indonesia, Malaysia, Papua New Guinea, the Philippines, the Solomon Islands, and Timor-Leste that holds more species of coral than anywhere else on the planet.³

Ecosystem Service—Any direct or indirect benefits that a natural ecosystem provides to humans.⁴

Mangrove—Tropical trees and bushes that are found along shorelines of salty bodies of water, adapted to withstand periods of being submerged by tides.⁵

Marine Protected Area (MPA)—An area of the marine environment that has been reserved by a government for the protection of its natural resources.⁶

Pelagic Fish—Fish that occupy the mid and upper layers of the open ocean, as opposed to fish that are associated with the seabed or coral reefs.⁷

Zooxanthellae—A group of single-celled algae known for forming symbiotic relationships with various marine organisms, notably corals.⁸

Context

Q: What are coral reefs?

A: Coral reefs, nicknamed the “rainforests of the sea,” are marine ecosystems known for their bright colors and biodiversity.⁹ Despite covering less than 1% of the area of the ocean floor, coral reefs are home to a quarter of all marine species.¹⁰ Scientists equate this to over one million total species living in these coral reefs.¹¹

Due to their unmoving nature, some of the very first scientists believed that corals were plants.¹² Scientists have since proven that corals are animals made up of thousands of smaller individuals known as polyps.¹³ Each polyp consists of a mouth surrounded by tentacles, which can extend at night to sting, prey, and feed.¹⁴

In hard or stony corals, these polyps secrete a calcium carbonate skeleton, then connect through living tissue over the top of this skeleton.¹⁵ This connection creates a coral colony, and as colonies grow together, reefs are formed. These reef structures can grow for years and can weigh several tons. Soft corals have a flexible protein skeleton, so for this reason, they do not build reefs. However, they are often found on reefs.¹⁶

One unique and important characteristic of corals is their symbiotic relationship with unicellular algae known as zooxanthellaeA group of single-celled algae known for forming symbiotic relationships with various marine organisms, notably corals.⁸.¹⁷ These tiny algae are photosynthetic, converting sun into energy for the coral animal in return for a safe place to live.¹⁸ This relationship is essential to the survival and productivity of corals, as all the corals’ daily metabolic requirements necessary for growth and cellular respiration are met through this photosynthesis.¹⁹

Q: Where are coral reefs found, and where is coral degradation occurring?

A: Coral reefs are found in oceans all across the world. Due to their need for sunlight to perform photosynthesis, many reefs are found in shallow waters, typically at a depth of less than 150 feet.²⁰ They also require tropical and subtropical temperatures (73–84 degrees Fahrenheit or 23–29 degrees Celsius), leaving them to be largely found in the waters around the equator, between 30 degrees north and 30 degrees south.^21,22 There are coral reefs found in deep waters, but due to the lack of sunlight, they do not have the symbiotic relationship with zooxanthellaeA group of single-celled algae known for forming symbiotic relationships with various marine organisms, notably corals.⁸ that shallow coral reefs do. This absence of a symbiotic relationship makes deep-sea coral less susceptible to environmental stressors and coral bleaching, and as a result, they will not be the focus of this paper.²³

Coral reefs are found worldwide, and their degradation is likewise global. In 2020, the Global Coral Reef Monitoring Network, working with the International Coral Reef Initiative, developed a report on the status of coral reefs worldwide. In their findings, these organizations saw that nearly every region of the world has experienced reef decline since 2010.²⁴

Additionally, since 2023, mass coral bleaching events (bleaching that affects an entire region of coral) have taken place in a variety of locations, such as the Caribbean, East Pacific, South Pacific, Middle East, and Southeast Asia.²⁵

Southeast Asia specifically is home to many of the world’s coral reefs. This region contains 78,272 square kilometers of coral reefs, more than any other recognized region.²⁶ This area is nearly 34% of the total amount of reef cover on the planet.²⁷ A section of this region has been dubbed the “Coral TriangleAn extremely diverse region of the ocean, spanning Indonesia, Malaysia, Papua New Guinea, the Philippines, the Solomon Islands, and Timor-Leste that holds more species of coral than anywhere else on the planet.³,” known for its high species richness and marine biodiversity.²⁸ The Coral Triangle has 600 of the 800 known species of reef-building corals (over 76%), 37% of the world’s reef fishes, and 51 of the world’s 70 mangroveTropical trees and bushes that are found along shorelines of salty bodies of water, adapted to withstand periods of being submerged by tides.⁵ species, making it the largest mangrove forest in the world.²⁹ Studies indicate that such a vast amount of coral cover may provide some natural resistance against environmental stressors, but this fact does not undermine the reality that 88% of reefs in Southeast Asia are under threat, with over half marked by marine biologists at “high or very high” risk.^30,31

Countries that are a part of Southeast Asia’s coral reefs include Brunei, Cambodia, Indonesia, Malaysia, Myanmar, the Philippines, Singapore, Thailand, and Vietnam.³² This area, where most of the Coral Triangle is located, is more affected by local threats than any other reef in the world due to the high levels of overfishing, pollution, and coastal development.³³ While it is important to look at all reefs in this region, coral in Indonesia, Malaysia, and the Philippines are considered to be the most at risk and therefore are the most studied.³⁴

Q: Who is impacted by coral degradation?

A: As some of the most diverse aquatic ecosystems on the planet, coral reefs are important globally—consequently, their degradation is also felt globally. However, no one is more impacted by the loss and destruction of coral reefs than coastal communities who live near them; over half a billion people are directly dependent on coral reefs.³⁵

Coastal communities rely on ecosystem servicesAny direct or indirect benefits that a natural ecosystem provides to humans.⁴, providing local communities food from reef fisheries, protection from natural hazards, and economic growth through fisheries and tourism.^36,37,38 Although not as commonly reported, communities capitalize on coral reefs’ valuable generation of sand, the cycling of nutrients, and the cultural ties these ecosystems have with locals.³⁸

Southeast Asia is considered to be one of the regions that is most dependent on coral reefs.³⁹ This dependence is due to the area’s proximity to the coast and its economic activities connected to coral reefs. Three hundred and fifty million people live within 50 kilometers of the coast, which makes it the most populous region of people residing near reefs.^40,41 Additionally, although some countries in Southeast Asia have experienced significant economic growth since the 1960s, countries such as Cambodia, Myanmar, and Vietnam are still among the poorest in the world.⁴² Most of the coral reefs are more at risk of consequences of coral degradation if surrounded by lower-middle-income countries.⁴³

Q: When did coral degradation begin?

A: Coral degradation has occurred for centuries due to overfishing by humans.⁴⁴ However, a lack of data and records make it difficult to detail how severe or intense this degradation has been—most detailed descriptions of coral reef ecosystems are from the last 50 years.⁴⁵ Despite this lack of historical data, even with signs of degradation before modern mass mortality events, it is clear that coral reefs are at a greater risk than ever before.⁴⁶ The scale of human impacts on coral reefs has grown at an exponential rate, and it is projected that reefs will see a decline of 70–90% from their current state by 2050.⁴⁷

In Southeast Asia, there is a similar lack of research on coral reef conditions. Data before 1990 is limited, which can lead to uncertainty when looking at long-term trends concerning coral degradation.⁴⁸ Nevertheless, recent economic and population growth in this region have resulted in further pressures on nearby coral reef ecosystems.⁴⁹

Contributing Factors

Climate Change

The United Nations defines climate change as long-term shifts in temperatures and weather patterns.⁵⁰ Unlike weather, which refers to local atmospheric conditions that regularly change, climate encompasses temperature, humidity, and precipitation conditions that span decades.⁵¹ The Intergovernmental Panel on Climate Change concluded that the global surface temperature from 2011–2020 was 1.09°C higher than it was from 1850–1900.⁵² Although 1.09 degrees does not seem significant, as of 2024, the 10 warmest years on record have all occurred since 2014, establishing the increasing severity of climate change.⁵³ Additionally, this single degree of change is already creating worldwide impacts such as sea-level rise and extreme weather events.⁵⁴ Changes to the planet’s temperature can be caused by natural processes, but human activities have been the main driver of climate change since the 1800s.⁵⁵ The burning of fossil fuels has produced excessive greenhouse gasses that trap heat in the atmosphere, bringing an estimated 1.07°C increase (of the total 1.09°C) in global surface area temperature since the 1850s.⁵⁶

Climate change has broad implications, but there is an especially profound impact on the health of coral reefs, causing coral bleaching and ocean acidification that can lead to coral mortality and inhibited growth.

Coral Bleaching

As of 2024, ocean heat was at its highest level in the 65-year observational record.⁵⁷ As temperatures increase annually, the threat to coral reefs continues to grow. Under these conditions, temperatures can exceed coral’s thermal limits, leading to coral death.⁵⁸ Additionally, even a slight increase of just 1°C in water temperatures can break down the symbiotic relationship between coral and zooxanthellaeA group of single-celled algae known for forming symbiotic relationships with various marine organisms, notably corals.⁸ through a process known as coral bleaching.^59,60 Most available research on climate change and coral reefs focuses on climate change’s role in coral bleaching. For this reason, this brief’s section will focus on coral bleaching’s contribution to the degradation of coral reefs through the loss of a coral’s main food source and an increased susceptibility to disease.

The term “bleaching” stems from the physical appearance of coral as it loses its zooxanthellaeA group of single-celled algae known for forming symbiotic relationships with various marine organisms, notably corals.⁸. In addition to providing coral with the nutrients essential for life, zooxanthellae are what give transparent coral polypsThe individual coral animals that grow together to make a larger coral colony.¹. their color.⁶¹

As such, when this algae is removed from the coral’s tissue, the white calcium carbonate skeleton underneath is exposed.⁶² Severe bleaching can be observed along a coral reef, as the majority of coral growth will turn white.⁶³ Corals that are experiencing bleaching seen by the naked eye have a density reduction of 70–90% of their algae.⁶⁴

Many assume that a bleached coral is dead, but this is not necessarily the case. After bleaching occurs, a coral can recover by regaining its zooxanthellaeA group of single-celled algae known for forming symbiotic relationships with various marine organisms, notably corals.⁸. However, if this algae is not recovered, the likelihood of coral mortality is high.⁶⁵ The extent of mortality varies depending on the severity of the event and the species of coral. Some events have caused the death of over 90% of corals in an area, and some species cannot survive more than 10 days without their zooxanthellaeA group of single-celled algae known for forming symbiotic relationships with various marine organisms, notably corals.⁸.^66,67 Without these symbiotic algae, corals must depend on energy stores or hunting to sustain their daily needs, leading to death through starvation.⁶⁸

This loss of energy also leaves corals particularly susceptible to additional issues that cause coral mortality, such as disease.⁶⁹ Reef ecologists suspect, and studies are beginning to show, a significant correlation between high water temperature events, bleaching, and the outbreak of coral diseases known as white syndromes.^70,71 These diseases are the most common coral afflictions around the world, characterized by lesions that cause tissue loss and death among corals.⁷²

Some scientists believe that corals expel their algae when in high water temperatures because stressful conditions cause the production of unstable, damaging oxygen molecules.^73,74 However, research on the actual link between these processes remains limited.⁷⁵ Regardless, what is clear is that most recent coral bleaching events have been the result of atypically high seawater temperatures.⁷⁶ Mass coral bleaching events, once occurring every 25–30 years, now occur an average of every 6 years.⁷⁷ If water temperatures drop and conditions return to normal, algae can return to the coral polypsThe individual coral animals that grow together to make a larger coral colony.¹., and the coral can gradually regain its health.⁷⁸ However, the current rate of bleaching is occurring at a rate faster than coral reefs can recover.⁷⁹

Southeast Asia is particularly susceptible to coral bleaching due to its coral reefs thriving at lower sea surface temperatures compared to other regions.⁸⁰ A study performed through the Global Coral Reef Monitoring Network revealed the impacts of the major 2010 coral bleaching event on reefs in Southeast Asia. In Malaysia and Cambodia, reports indicated bleaching along 75–90% of reefs.⁸¹ Thailand saw bleaching of 80% of its reefs, and in Wakatobi, Indonesia, 60–65% of corals exhibited signs of bleaching with 10–17% of colonies fully bleached.⁸² Indonesia experienced an even higher magnitude of bleaching in 2016.⁸³ Coral mortality from these events is not well documented and varies by coral species.

Acropora, one of the most diverse and abundant coral genera with approximately 180 species, plays a vital role in reef-building due to its rapid growth and function as a foundational structure for other corals and marine organisms.^84,85,86 They are also one of the more sensitive genera to the effects of climate change, such as coral bleaching.⁸⁷ In 2010, Indonesia saw an 80% loss of Acropora corals, while mortality rates in Thailand reached up to 90%.⁸⁸ In 2016, half of the Acropora corals in the Philippines’ Palawan Islands died within four months.⁸⁹ Even with little documentation, it is clear that coral bleaching is degrading coral reefs in the Southeast Asian region.

Ocean Acidification

In addition to raised seawater temperatures causing coral to bleach, climate change has another impact on coral reefs. As carbon dioxide (CO2), a prominent greenhouse gas, is released into the atmosphere through human activities, around 25% of those emissions are absorbed by the ocean. This absorption triggers chemical reactions that reduce the ocean’s pH, making the water more acidic.⁹⁰ The ocean’s pH has decreased from 8.2 to 8.1 since the Industrial Revolution, making the water 25% more acidic than it was before. This is a rate 10– 100 times faster than previously seen in the past 100 million years.^91,92 High acidity reduces a coral’s density of zooxanthellaeA group of single-celled algae known for forming symbiotic relationships with various marine organisms, notably corals.⁸ and decreases its skeletal growth.⁹³ Current scientific theory proposes that acidic conditions may prevent or reduce the deposition of calcium carbonate from the reef, a necessary material used for their skeleton, reef building, and growth.^94,95 Ocean acidification can also cause coral skeletons to dissolve, the same way chalk (which is made up of calcium carbonate) dissolves when put in acidic vinegar.^96,97 This dissolution showcases the threat ocean acidification poses to the long-term health of coral reefs.⁹⁸

Data on the impacts of ocean acidification in Southeast Asia is less robust than that of coral bleaching.⁹⁹ Despite this lack of data, studies show that Southeast Asia’s coral reefs are at an above-average risk of degradation due to ocean acidification.¹⁰⁰ This change in seawater chemistry can shift the region’s coral reef communities, welcoming competitive and weedy species, and can overall degrade habitat suitability.¹⁰¹ Published in the Journal of the International Coral Reef Society, these findings show that coral species in Thailand experienced reduced calcification rates (skeletal growth) due to ocean acidification.¹⁰²

Destructive Fishing

An estimated 56% of coral reefs in Southeast Asia are under threat due to destructive fishing practices.¹⁰³ Generally, destructive fishing refers to any fishing method that destroys fish habitat.¹⁰⁴ In Southeast Asia, there are two main types of destructive fishing techniques: blast fishing and poison fishing. In both cases, these local fishing approaches degrade coral reefs by destroying corals and inhibiting future growth.^105,106

Blast Fishing

Blast fishing refers to the use of explosives to stun or kill fish.¹⁰⁷ These explosives are a cheap and easy way for fishermen to collect fish that are killed by resulting shockwaves.¹⁰⁸ However, this process degrades coral reefs by physically damaging them and disturbing their habitat. Following World War II, unexploded shells that were left behind were used as bombs for fishing.¹⁰⁹ In modern times, fishers use dynamite, grenades, or homemade explosive devices.¹¹⁰ Although blast fishing is illegal, it has been recorded on nearly every continent since the nineteenth century.¹¹¹ In Southeast Asia, blast fishing is practiced in thirty countries and remains a particular problem in Malaysia, Indonesia, and the Philippines.^112,113,114 In a literature review of recorded blast fishing across 14 different regions, 50.5% came from Southeast Asia, demonstrating how concentrated this illegal practice is in the area.¹¹⁵

The practice of blast fishing has devastating consequences for coral reefs. At the most extreme level, hard coral structures can be reduced to rubble as a product of explosions.¹¹⁶ A one-kilogram homemade beer bottle explosive can leave a crater 1–2 meters in diameter, and regularly blasted reefs exhibit coral mortality of 50–80%.¹¹⁷ Blast fishing also degrades coral reefs by making it difficult for coral reef colonies to regrow.

Studies have shown that coral reefs exposed to chronic disturbances or physically altering disturbances are less likely to recover than those that experience acute disturbances, which leave the habitat intact.¹¹⁸ As large areas of rubble shift, new coral recruits (baby corals) are hindered as they are scraped away or buried.¹¹⁹ Additionally, after researchers monitored rubble fields in Indonesia following blast fishing, they found that soft coral growth often dominated, reducing the ability of hard, reef-building coral to survive.¹²⁰

With the cost of bombs between $1–2 and a catch with a market value between $15–40, the practice of blast fishing is likely economically motivated.¹²¹ Despite this economic incentive, there is no consensus on the role socioeconomic status and poverty play in the prevalence of blast fishing. Some believe that poverty is a main driver, but others believe that it has more to do with access to destructive equipment and the ease of generating higher incomes.¹²²

The full extent of blast fishing in Southeast Asia has not been quantified. Detectors from Hong Kong, Malaysia, and the Philippines have recorded over 850,000 blasts from 2006–17, but this number likely comprises only a portion of the blast fishing occurring across the entire region.¹²³

Poison Fishing

A second destructive fishing practice commonly seen is known as poison fishing, a practice that originated in the Philippines during the 1960s and has since spread to Indonesia, Vietnam, and parts of Malaysia.¹²⁴ For this method, fishers dive down into coral reefs and squirt poisons (usually sodium cyanide or bleach) into crevices where fish live. Doing this stuns fish, allowing them to be easily caught. As such, this type of fishing is common for catching live fish—either for food or ornamental fish for the aquarium industry.^125,126 However, poison fishing leads to coral degradation because it can cause coral bleaching and, in many cases, coral death.

Photo by unsplash

Poison fishing, particularly prevalent in Southeast Asia, is commonly used to catch live aquarium fish. This global industry moves an estimated 20–30 million fish annually, of which 80% is collected from the Philippines, Indonesia, and Sri Lanka.¹²⁷ Within this industry, approximately 50% of wild-caught fish brought to the US were tested to have exposure to cyanide.¹²⁸

This testing indicates the high likelihood that poison fishing is common in Southeast Asia. Additionally, estimates show that in the Philippines specifically, one million kilograms of cyanide have been used for fishing since this technique began in the 1960s.¹²⁹ Nevertheless, because poison fishing usually occurs in isolated coral reef systems, the full extent of poison fishing is unknown.¹³⁰ Even greater risk arrives because some reefs in the Indo-Pacific (which includes the majority of Southeast Asian reefs) are threatened by larger fishing boats dumping 100–200 liter containers of cyanide to catch live fish for human consumption.¹³¹

Poison fishing has clear consequences for the health of corals. Experiments done in laboratories to mimic cyanide concentrations typical of poison fishing techniques showed that coral polypsThe individual coral animals that grow together to make a larger coral colony.¹. with zooxanthellaeA group of single-celled algae known for forming symbiotic relationships with various marine organisms, notably corals.⁸ experienced bleaching or death as a result of exposure.¹³² Despite these experiments, there is no complete scientific agreement that poison fishing is degrading entire coral reefs.¹³³ Still, some scientists estimate that a square meter of coral is destroyed for every fish that is caught via poison fishing.¹³⁴ Additionally, as fish tend to hide in crevices to escape divers, the divers often have to hammer and pry open corals to get to the stunned fish, causing even more physical damage to the corals.¹³⁵ Overall, in the coral reef wildlife trade, poison fishing is likely the single largest source of mortality and environmental damage.¹³⁶

Pollution

A final factor contributing to the decline of coral reefs in Southeast Asia is pollution because sediments and increased nutrients can smother corals and result in their death. This pollution can originate from both the sea and the land.¹³⁷ Marine pollution often comes from ports, oil spills, and waste dumped from ships. Inland pollution arises as poor agricultural practices and land-use changes erode soil that then enters rivers.¹³⁸ These processes increase the amount of sediment and nutrients that enter the ocean. This rise in nutrients is known as eutrophication.¹³⁹ Eutrophication refers to conditions where the nitrogen and phosphorus levels become so high that the productivity of plant life and microbes greatly increases—to the detriment of other life forms.¹⁴⁰ One reason for this condition is because with rapid growth, other organisms (such as algae) out-compete coral which increases the severity of coral diseases.¹⁴¹

High sedimentation results in coral reefs being smothered, requiring coral to spend increased time and energy to clear the debris. If sediment loads become too high, the coral can be buried and eventually die.¹⁴² Additionally, if there is too much sediment in the water, it can become cloudy. Since corals are dependent on the process of photosynthesis and sunlight, foggy waters can stunt growth and even lead to death.¹⁴³

Source: Unsplash

In Southeast Asia, marine pollution threatens 7% of reefs, and land-based pollution threatens 20% of reefs.¹⁴⁴ Due to rapid economic development, urban and industrial pollution in this region continues to grow, increasing the threat to coral reefs in the area.¹⁴⁵ In Jakarta, Indonesia, 80% of wastewater runs directly into rivers through an open ditch system. This lack of sewage treatment combined with large-scale agriculture has caused high nutrient levels in these coral reefs, damaging their integrity.¹⁴⁶ Several large cities in Indonesia, such as Makassar and Manado, have seen a decrease in coral reefs due to land-based pollution.¹⁴⁷ Similarly, reefs in Indonesia have experienced up to a 60% loss in biodiversity because of eutrophication.¹⁴⁸ In Port Dickson, Malaysia, measurements of coral skeleton phosphorus increased up to 8-fold over the late 20th century, indicating the amount of phosphate (an essential nutrient) that exists in the water.¹⁴⁹ This increase in coral skeleton phosphorus coincided with an 18% decrease in coral skeleton density.¹⁵⁰ Finally, Manila Bay in the Philippines has seen a 2–8 fold increase in sedimentation rate in its oceans, which may contribute to the observed decline in coral reefs.^151,152

Consequences

Decline of Fisheries

Of the 1 million species that depend on coral reefs, more than four thousand are fish species.¹⁵³ Due to this high number, coral reefs are essential to the success of fisheries.¹⁵⁴ In both nurseries and adult habitats, many fisheries exist only to the extent of the presence of coral reefs.¹⁵⁵ Studies have shown a positive correlation between the complexity of reefs and the abundance of fish, modeling that loss of reefs could result in a three-fold reduction in the productivity of fisheries.¹⁵⁶ Healthy reefs were seen to produce as much as four tons of fish per square kilometer annually, while degraded reefs had yields as low as 0.7 tons.¹⁵⁷ As coral reefs in Southeast Asia degrade, fisheries in the region face a significant decline. This loss has profound consequences for coastal communities, as these fisheries are vital to their economy, livelihoods, and food supply.¹⁵⁸

In 2017, commercial fisheries in the Coral TriangleAn extremely diverse region of the ocean, spanning Indonesia, Malaysia, Papua New Guinea, the Philippines, the Solomon Islands, and Timor-Leste that holds more species of coral than anywhere else on the planet.³ provided an estimated $5.85 billion in economic returns.¹⁵⁹ The value of fisheries in Southeast Asia is estimated at $2.4 billion annually, accounting for 10% of the region’s gross domestic product (GDP).^160,161 While the region’s Marine capture fisheries only make up 39% of fish production, they represent 51% of the value of all fisheries.¹⁶²

However, it is now estimated that 64% of the region’s fisheries are facing a medium to high-level threat of collapse.¹⁶³ This threat highlights the particular importance of coral reefs as fish habitats contributing to the success of fishing industries in Southeast Asia and the economy it supports.

Additionally, the decline of fisheries has more specific impacts than those on the general economy. In the Coral TriangleAn extremely diverse region of the ocean, spanning Indonesia, Malaysia, Papua New Guinea, the Philippines, the Solomon Islands, and Timor-Leste that holds more species of coral than anywhere else on the planet.³, 130 million people rely on fisheries for food, income, and their livelihood.¹⁶⁴ These fisheries are paramount for coastal communities and people who are involved in small-scale fishing. For example, the Philippines has over one million people who rely on coral reef fisheries for their income.¹⁶⁵ While reef fish contribute only 8–20% of the Philippines' total fisheries, small island fisheries rely on reef fish for as much as 70% of their total catches.¹⁶⁶ Nevertheless, there has been an observed decline in small-scale fisheries in Southeast Asia. Malaysia has seen biomass in coastal waters decrease by as much as 80%, and Myanmar has seen a decline as high as 90%.¹⁶⁷ Despite this decline, small-scale fishing in Southeast Asia continues, even if it means diminishing catches, longer workdays, and greater distances. While the exact reason for this apparent contradiction is not clear, it is suggested that a lack of viable livelihood alternatives and assets necessary to transition may be what keeps these communities fishing-based.¹⁶⁸

Reduction in Tourism

Another consequence of coral reef degradation in Southeast Asia is the potential for a reduction in tourism, which can disrupt the region’s economy, employment base, and development. In a case study looking at Mu Ko Surin Marine National Park (MKSNP), located in Thailand, researchers attempted to determine what role healthy, pristine reefs played in tourism and visitor satisfaction. The study found that the park’s coral reefs were the main motivation behind the tourists’ visit to the park (both foreign and from Thailand). Further, 96.8% of visitors who had been to MKSNP before reported participating in snorkeling, with 12.7% participating in diving.¹⁶⁹ These results indicate that, at least for MKSNP, the presence of coral reefs is central to the tourism industry. When these same tourists were asked about their satisfaction with the park, 99% of respondents claimed that coral bleaching was one factor that negatively impacted their experience.¹⁷⁰ While it cannot be concluded for certain that coral bleaching will reduce tourism at this location, MKSNP did close five tourist destinations in 2010 at the request of the Department of National Parks, Wildlife and Plant Conservation of Thailand. The closure was intended to prevent reef loss and to aid in coral rehabilitation, yet it also reduced the number of tourists in the park by almost one-half.¹⁷¹ As such, regardless of the cause, coral reef degradation reduced the amount of tourism in Thailand.

Another study looking at the impact of the 1998 coral bleaching event (perpetrated by the El Niño phenomenon) on tourism in El Nido, Philippines, saw a similar decline in tourism. For example, researchers found that 91% of El Nido’s visitors went snorkeling during their visit, and 47% went scuba diving.¹⁷² Additionally, most of the tourists appeared interested in the coastal ecosystem, with only 5% saying that “marine life” was not important to them.¹⁷³ However, in 2000, El Nido sustained some major losses. In the 1980s, there were around 20 good diving spots, but in 2000 there were less than a dozen. This shortage resulted in an estimated loss of 500 dives per year, which equated to a loss of $10,000 a year. Even larger, an estimated 4,000 resort guests were lost, resulting in a net revenue loss of $2 million.¹⁷⁴ The researchers estimate that half of this total loss can be directly attributed to the El Niño-induced bleaching event.¹⁷⁵ These findings further illustrate the potential risks reef degradation poses to Southeast Asia’s tourism industry.

A reduction in tourism creates considerable risk for the region, especially because Southeast Asia is known as one of the top diving destinations in the world.¹⁷⁶ Dive tourism is a major source of income for many of the coastal and inland communities in the region, and coral reef recreation generally holds high economic value in Southeast Asia.^177,178 This value is represented by the nearly $5.8 billion revenue and over 35 million visitors that are brought in through coral reef tourism annually.^179,180,181

A study of the economic loss accompanying coral reef destruction in the Philippines found that blast fishing could cause a loss of $400,000 in tourism potential.¹⁸² An analysis of the 2010 coral bleaching event in Thailand, Indonesia, and Malaysia estimated the economic impact of degradation from dive tourism was between $50 million to $80 million.¹⁸³ This value may not seem significant from a national perspective, but it is for the many individuals whose lives are reliant on tourism. Nearly 16 million people are employed in tourism in Southeast Asia.¹⁸⁴ In Koh Tao, Thailand, a city that supports the livelihoods of over 1,800 people, the majority of residents are involved in diving tourism.¹⁸⁵ On the small Karimunjawa Island in Indonesia, locals view tourism as benefiting the island through the production of jobs and improvement of facilities.¹⁸⁶ These benefits can be felt by many communities in Southeast Asia and could be lost if coral reefs continue to degrade.

Minimized Coastal Protection

A final consequence of the degradation of coral reefs in Southeast Asia is a depletion in coastal protection. Coral reefs, due to their complex, three-dimensional structure, play an essential role in protecting the coastlines they are near, shielding shores from incoming waves and storms.¹⁸⁷ This protection can be physically viewed from an aerial perspective, as waves break at the coral reefs and turn into calm water near the coastline.¹⁸⁸ Reefs are extremely successful at providing this protective ecosystem serviceAny direct or indirect benefits that a natural ecosystem provides to humans.⁴ as well, with corals able to absorb an average of 97% of incoming wave energy and reduce an average of 84% of wave height globally.¹⁸⁹ Notably, this 97% reduction refers to the amount of energy in both small waves and hurricane-level waves.¹⁹⁰ Coral reefs, acting as a natural barrier, play an important role in the success of coastal communities, preventing erosion, flooding, property damage, and loss of life.¹⁹¹

When coral reefs are degraded, their ability to protect shores and coastlines is diminished because a loss of living coral signifies a loss in the structural complexity that dissipates wave energy.¹⁹² This reduction in complexity perpetuates larger wave heights in back reefs and erosion of shores.¹⁹³ Unprotected coastlines are also more at risk of damage from waves and storms, especially flooding.^194,195 A study of over 7,000 people living in low-lying coastal areas exposed to hazards in Southeast Asia found that 35.4% of this population avoided flooding for over 10 years because of coral reefs.¹⁹⁶

It is well documented that countries in Southeast Asia are particularly at risk for coastal flooding and erosion. For example, by 2100, it is estimated that 5.9 million people will experience flooding annually in Indonesia.¹⁹⁷ However, due to a lack of data, most of this flooding is connected to sea-level rise, which is predicted to be an average of 0.54 and 0.71 meters globally by the end of the 21st century.^198,199 Still, scientists believe that coral reef destruction can intensify these conditions, which cause flooding, land loss, and forced migration.²⁰⁰ Globally, through modeling 100-year flooding events, researchers have quantified a 116% increase in the amount of land flooded and a 91% increase in damage costs when projected sea-level rise is coupled with a one meter loss of coral reef height.²⁰¹

Although the benefits that come from coastal protection are not always distinctly visible in a country’s GDP, efforts have been made to quantify the economic profit brought by coral reefs’ shore-protecting abilities.²⁰² For the population of the 7,000 individuals who avoided flooding, experts estimated that coral reefs prevented a 35.7% loss in GDP over 10 years.²⁰³ The World Resources Institute also evaluated coastal protection as having the potential to generate between $5,500–$110,000 annually per square kilometer of healthy coral reefs in Southeast Asia.²⁰⁴ This extensive range is the result of examining areas of medium and high development. They further detailed the economic benefits, estimating the annual net support provided by coastline protection at $314 million for Indonesia and $326 million for the Philippines.²⁰⁵ Finally, as a whole, it is estimated that Southeast Asia saves over $2.3 billion through the avoidance of coastal infrastructure damage.²⁰⁶

Practices

Marine Protected Areas

Marine Protected Areas (MPAs)An area of the marine environment that has been reserved by a government for the protection of its natural resources.⁶ are sections of the ocean that have been set aside by a governmental body with regulations on human activity.²⁰⁷ Typically, these regulations are on extractive uses that take natural resources from the environment, especially certain types of fishing.²⁰⁸ MPAs can range in intensity, from allowing people to use the area in non-damaging ways to complete public closure.^209,210 Hundreds of MPAs have been created for Southeast Asia at the local, provincial, national, and even international levels, depending on the value of the area and risk of threats.^211,212 Goals for these MPAs can vary but tend to be for the management of fisheries, the promotion of tourism, and biodiversity protection; MPAs are usually managed through a central government program.²¹³ In Southeast Asia, the majority of MPAs are classified as national parks, or as protected areas that allow the sustainable use of natural resources.²¹⁴ MPAs affect the way humans interact with marine ecosystems, making it a direct strategy for protecting coral reefs.²¹⁵

Impact

When successfully managed, MPAsAn area of the marine environment that has been reserved by a government for the protection of its natural resources.⁶ have a positive impact on the condition of coral reefs. In a study analyzing four MPAs in the Philippines and Indonesia, it was found that all the areas had biological success, with an increase in fish abundance, fish biodiversity, andcoral substrateThe material that coral polyps attach and grow on, such as live coral, dead coral, rock, rubble, and sand.².²¹⁶ At a different MPAAn area of the marine environment that has been reserved by a government for the protection of its natural resources.⁶ on Apo Island in the Philippines, biologists saw the populations of two reef fish triple over an 18-year period.²¹⁷ Similarly, an evaluation of an MPA in Bintuan, Philippines, noted a 40% decrease in dead coral cover within the MPA and a 14% increase in live coral cover outside the MPA.²¹⁸ Positive results have also been seen in other parts of the world, such as in the Great Barrier Reef in Australia. Over the span of 20 years, reefs in these MPAs stabilized up to 38% more and recovered 20% faster than reefs in unprotected areas.²¹⁹ Studies have also shown that MPAs can increase catches by improving fish diversity and density and can increase the aesthetic and recreational appeal that brings in tourism.^220,221 For example, looking at seven MPAs in Southern Europe, there was a 2–4% increase in the market catch of adjacent fisheries every year over a 30-year period.²²² A different study examining tourism revealed that MPAs contributed $21,446 in tourism in St. Martins and $25,375 in Vanuatu.²²³ These results show the potential benefits MPAs can bring when successfully managed.

Gaps

While scientists and resource managers believe that MPAsAn area of the marine environment that has been reserved by a government for the protection of its natural resources.⁶ can be an effective solution, large gaps remain in the implementation and evaluation of these areas. Of the 332 MPAs in Southeast Asia, only 14% are rated as being effectively managed.²²⁴ This lack of efficient management is likely due to minimal staff and resources allocated for enforcement and monitoring.²²⁵ Additionally, while MPAs can be biologically successful, they may not be socially successful. For example, economic benefits may not be widely shared, resulting in conflict and a lack of engagement from stakeholders.²²⁶ If local communities must completely change their livelihoods to comply with an MPA without adequate preparation or resources, significant pushback and compliance challenges may arise.²²⁷ As such, to truly see the success of MPAs, there need to be integrated studies on the impact in these areas and increased commitment from governments and other stakeholders for successful management.^228,229

Coral Transplantation

To restore and rehabilitate coral reefs that are degraded, areas around the world have begun transplanting healthy coral into damaged areas. Transplantation is often used for reefs that struggle to recover on their own or where natural recovery is extremely slow.²³⁰ There are many techniques and methods for coral transplantation, but this section of the brief will focus on the Mars-Assisted Reef Restoration System or MARRS. This technique, developed by the company Mars and piloted in Sulawesi, Indonesia, involves attaching coral fragments to hexagonal steel structures (known as “spiders”) to aid in regrowth.²³¹

Impact

The Mars Team initially installed 11,000 spiders in South Sulawesi, Indonesia, an area where blast fishing had left reefs as rubble fields unsuitable for coral survival and growth.²³² In one section of the rehabilitation area, 7% of the site had natural live coral, and an additional 8% of live coral was added through attachment to the spiders. Returning a year later, it was found that live coral cover had increased to 48%.²³³ Across the entire rehabilitation area, coral cover was estimated to increase by 40% due to the spiders.²³⁴

This technique has also been replicated in other places in Indonesia and has seen similar success. In the Bone Bolango Regency, coral reefs transplanted via spiders saw growth of 0.3 cm per day with a 100% survival rate.²³⁵ In Makassar City, transplanted corals saw a total growth of 9.22 cm and a 58.15% survival rate over a two year period.²³⁶ These results indicate that the MARRS system for coral transplantation is successful and scalable.²³⁷

Gaps

While this method of coral rehabilitation proves to be very effective, two main gaps have not been addressed. First, no research or evaluation has been done on the impact these spiders have on the coastal communities near them. While there is hope that improving the health of coral reefs will, in turn, improve the condition of local fisheries, tourism, and coastal protection, there is no definitive monitoring of these outcomes.²³⁸ Second, as successful as these transplantations are, they can easily be destroyed again if human disturbances are not kept under check.²³⁹ More comprehensive studies of MARRS, combined with integrated rehabilitation efforts, can enhance the success of coral transplantation in Southeast Asia and benefit the coastal communities that rely on these reefs.

Preferred Citation: Smith, Paige. “The Impact of Coral Degradation on Coastal Communities in Southeast Asia.” Ballard Brief. February 2025. www.ballardbrief.byu.edu.

Viewpoints published by Ballard Brief are not necessarily endorsed by BYU or The Church of Jesus Christ of Latter-day Saints

By Paige Smith

Published Winter 2025

Special thanks to Mason Scholes for editing and research contributions.