The Adverse Impact of Anthropogenic Activities on Coral Reef

Xinran Liang

United World College of Changshu China, Suzhou, Jiangsu, 215500 China

Keywords: Coral Reef System, Anthropogenic Activities, Sipadan, Coral Protection.

Abstract: Coral reefs are one of the main habitats for marine organisms, located in the coastal areas, fostering around

35,000 to 60,000 species of animals. They provide protection and economic services to humans, generating

millions of dollars per year from tourism and other uses. However, 50% of the world’s coral was lost in the

last 30 years due to global warming and other anthropogenic activities. Its annihilation process is swift from

the fast coral bleaching that the coral undergoes from healthy to dead as a result of combined human activities

of garbage disposal, illegal trading, chemical pollution, unsustainable overfishing, intensive tourism, and

global warming. There are multiple cases of mass coral bleaching worldwide, such as the 1998 cases that

struck Sabah, Borneo. Sipadan is an example of an area that sustains a great variety of coral reefs, well

protected by legislation and agreements. However, its methods have their deficiencies when viewed from a

larger scale, such as driving fishermen to other islands nearby and destroying other coral reefs. More solutions

regarding this issue should be discussed, with consideration of different stakeholders. The article analyze the

anthropogenic activities’ impacts from two points of view: direct and indirect. Later on, it will focus on the

applicable solutions for the future of this issue concerning the case of Sipadan.

1 INTRODUCTION

Coral reef, the underwater wonders supported by

calcium carbonate construction secreted by coral, is

the home to 35,000 to 60,000 species in the marine

ecosystem. In addition to shielding the shore areas

from ocean waves, it serves as a haven for a diversity

of aquatic life. It is sustained through a symbiotic

relationship with the algae zooxanthellae, where the

zooxanthellae obtain needed shelter, carbon dioxide,

and nutrients from the coral and then provide oxygen

and remove waste for the coral. Due to the need for

photosynthesis of its symbiotic algae zooxanthellae,

coral reefs are often located up to 100m in depth and

generally in coastal areas, making them susceptible to

human activities. As a result, the depletion of coral

reefs is increasing due to different human activities,

such as overfishing, global warming, tourism, etc.,

which will eventually lead to the habitat annihilation

of 25% of the marine organisms (El-Naggar and

Hussein, 2020). Although there is a lack of

quantitative information on the effects of

anthropogenic activities, it is estimated that almost

60% of coral reefs are affected by these activities

(Wilkinson, 2008). There is multiple research that

show the correlation between the quantity of certain

human activities and the health of coral reefs, yet few

researches offer discrete solutions to the mass coral

bleaching that is happening worldwide. It is

noteworthy that a particular action may have a

number of diverse effects, all of which when

combined might result in coral bleaching and the

coral disease spreading.

The coral reef is an important component

biologically and economically of the Southeast Asian

region, yet no systematic research has been conducted

on the long-term anthropogenic stressors and the

effectiveness of the various legislation that is being

applied to the area. However, there is extensive

research into the coral reef biodiversity and the coral

reef cover throughout Malaysia, offering footstone

into the research about human activities and coral

degradation. To some extent, the establishment of

coral-protected areas is crucial to the preservation of

coral reefs in Malaysia as its economic growth and

coastal population continue to rise.

Although there are some actions taken worldwide,

focused on the different organizations that are trying

to encourage people to put action into coral protection

actions such as Coral Watch, governments and

companies need to put more effort and investments

into these projects. Laws such as the Environmental

Quality Act (1974) and the Customs (Prohibition of

Exports Amendment No. 4) Order (1993) safeguard

Liang, X.

The Adverse Impact of Anthropogenic Activities on Coral Reef.

DOI: 10.5220/0013844400004914

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 2nd International Conference on Renewable Energy and Ecosystem (ICREE 2024), pages 41-46

ISBN: 978-989-758-776-4

coral reefs in Malaysia (Praveena et al., 2012).

However, the effectiveness of these legislations has

remained to be questioned. Aside from law

enforcement, awareness is also an issue to be

addressed as research on coral conservation

awareness in the Terengganu community of Malaysia

shows that 55.3% of the sample have acceptable

knowledge of coral reefs and only 29.0% of the

sample had good coral reef protection practices

(Marzo et al., 2023).

Therefore, the objective of this article will focus

on how anthropogenic stressors may directly and

indirectly affect the coral reef population, and hence

how these impacts can be mitigated through different

socioeconomic and political restrictions.

2 CASE DESCRIPTION

Sipadan is Malaysia’s only oceanic island, formed by

coral reefs growing on top of a volcanic cone. It is

famous for its turtle and coral reef, especially among

scuba divers and snorkelers, classified as one of the

world’s top 10 diving sites. It was described as “an

untouched piece of art” as it is in the coral triangle

and consists of over 600 different coral species and

nearly 3,000 different fish species (Musa and Ghazali,

2002). Dr. Elizabeth Wood from the British Marine

Conservation Society began her ongoing monitoring

of Pulau in 1992 and saw a noticeable decline in the

number and quality of the coral reefs. Furthermore,

the shallower parts of Sipadan's reef were completely

destroyed by the tropical storm Greg in 1996. And

because of global warming and rising ocean

temperatures, the reef is impossible to regenerate and

recover. Of Malaysia's variety of coral reefs, 97%

were classified as threatened in 2011, and 50% as

highly vulnerable to severe degradation (Burke et al.,

2011). Later on, there are several policies established

to restrict the proficiency and number of tourists that

are allowed on the island to effectively protect the

coral reefs. Sabah Parks declared on September 22,

2022, that starting on October 1, 2022, only ones who

possess Advanced open water level certificates and

Sipadan permits will be able to dive at Sipadan, with

a maximum of two dives permitted (Musa and

Ghazali, 2002).

Over 70% of Indonesia’s reefs have suffered

significant damage from natural causes and

anthropogenic activities, according to the Ministry of

Marin Affairs and Fisheries (Tuwo, 2011). However,

due to the variety of protection acts in Sipadan, the

coral reef condition in Sipadan was found to be in the

finest condition in the Sibah islands.

3 ANALYSIS OF

ANTHROPOGENIC

STRESSORS’ IMPACT ON

CORAL REEF

3.1 Direct Impact of Human Activities

3.1.1 Traffic Boat

Because of its propeller string and anchoring

mechanism, boats have the potential to harm the

marine environment, particularly coral reefs,

physically or mechanically (El-Naggar and Hussein,

2020). According to research conducted in the British

Virgin Islands, the coral coverage, especially hard

coral coverage differs significantly from low

anchoring sites to high anchoring sites (Flynn and

Forrester 2019). The research result by the team is

shown in the table 1 below:

Table 1. Anchoring Level’s Impact on Coral’s Percentage Cover (Flynn and Forrester 2019)

Taxonomic Group

Low anchoring sites

(percentage over)

Medium anchoring

sites (percentage

cover)

High anchoring

sites (percentage

cover)

Proportional change

in cover (H-L)/L

Hard coral

17.05 ± 2.4 16.06 ± 2.3 9.91 ± 1.9

-0.42

Sea Fan

12.78 ± 5.9 4.71 ± 3.9 5.00 ± 0.4

-0.61

Soft Branching Coral

18.58 ± 6.3 19.15 ± 6.4 13.20 ± 5.7

-0.29

Dead coral

2.57 ± 2.0 2.80 ± 3.7 6.47 ± 3.55

1.52

The different levels of anchoring sites (low,

medium, and high) are classified by different

densities of anchoring activities as observed by the

satellite imagery, with no obvious differences in

proximity in land-based factors. As shown from the

research, at high anchoring sites, coral coverage is

approximately 39% smaller than that of low or

medium anchoring sites, showing a strong correlation

between the coral colony sizes and the amount of

anchoring activities. Furthermore, mound corals and

branch corals are most severely damaged, indicating

coral loss is mainly the result of anchor chain

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sweeping and other physical damages (Flynn and

Forrester 2019).

However, the impact of traffic boats is an

inevitable destruction of coral reefs because it’s the

only method of inter-island transportation and it is

necessary for the economic development of a certain

island. Aside from the physical damage, most of the

boats that connect Semporna to other islands are

fueled by oil, inevitably causing oil and toxin leakage

into the ecosystem and the noise from ships may

cause disruptions to the fish living in the coral reef

(El-Naggar and Hussein, 2020).

3.1.2 Garbage Disposal

In Malaysia, more than 80 percent of people reside 50

kilometers or less from the coast, and they are

overexploiting the country's natural resources (Asian

Development Bank, 2014). An assessment was

conducted on the Malaysian islands of Mamutik,

Manukan, and Sapi, showing an abundance of marine

debris, mainly consisting of plastic bags, plastic

bottles, polystyrene, and plastic cups, in the intertidal

zones (Zahari et al., 2022). The most prevalent marine

debris found in the Malaysian islands is plastic bottles

and plastic cups, which take up to 450 years and 50

years, respectively, to fully break down (Zahari et al.,

2022). These plastic debris have a direct impact on the

coral reef as they create openings to pathogens like

ciliates or introduce pathogens directly such as

Rhodobacterales carried in polyvinyl chloride (PVC)

(a very common material used in children’s toys and

building materials). In fact, common coral diseases,

such as skeletal eroding bands, white syndromes, and

black bands, are more prevalent in corals that are

greatly impacted by plastic wastes, leading to a higher

mortality rate. In addition, microplastics are eight

times more likely to be trapped in the more complex

and branched corals, causing a greater impact on the

structurally complex corals. Such a result may lead to

macroplastic debris blocking out light for

photosynthesis and resulting in a low-oxygen

condition that favors the growth of microorganisms,

leading to coral diseases such as the black band (Lamb

et al., 2018).

There is usually poor waste management on small

islands because the daily wastes do not have an

efficient disposal method except for being thrown

into the ocean. Especially for poor islands, cannot

afford the high cost of transporting or breaking down

the waste through artificial methods as the

transportation is inconvenient on the island. To

address this issue, more efficient and convenient

garbage disposal methods should be researched and

developed.

3.1.3 Illegal Trading

The commercial coral harvesting industry persists

despite global legislation that limits the exploitation

of coral reefs governed by the Convention on

International Trade in Endangered Species.

According to the NMFS analysis, the international

trade of corals and live rocks has increased at a rate

of 12 to 30 percent per year since 1990. Certain

species such as the red coral have high economic

value and culture, tempting the merchants to acquire

them illegally to make money. In fact, red coral has

been collected for 5,000 years as Ancient Egyptians,

Romans, and Greeks used them as jewelry, and

people in the Middle Ages used them to ward off

witches. The CITES Trade Database states that

between 2011 and 2015, around 210 tons and 80,000

pieces of raw Corralium corals that were listed under

the CITES were imported worldwide (Tsounis et al.,

2010). Large businesses also collect coral reefs as

souvenirs or aquarium trade. Furthermore, the general

population is unaware of how crucial coral is to the

ecology, particularly dead and bleached coral.

Therefore, it is common for tourists to take dead and

stony corals as souvenirs or ornaments from trips to

the ocean sides.

3.1.4 Chemical Pollution

Fertilizers and pesticides may result in the marine

ecosystem through runoffs from farmlands. The

harmful pesticides will accumulate inside the coral

reef and even pass down along the food chain,

causing a greater impact on the ecosystem and

humans. Studies are conducted on H.micronos, F.

speciosa, and P. lobata in the Sabah islands to

measure the concentration of heavy metals. It was

found that the amount of iron and nickel is

significantly higher than that of other metals, but the

chemical pollution condition in Sabah islands is not

as severe as it is in other islands (Mokthar et al., 2011).

Chemical leaks and spills, which are mostly the result

of oil tanks, pipelines, and harbors, affect coral reefs'

ability to grow, feed, defend themselves, reproduce,

and organize their cells (El-Naggar and Hussein,

2020).

The concentration of different chemicals in the

coral reef may lead to different implications of the

contamination that the coral is exposed to. For

example, a high concentration of zinc in coral species

shows a high value of zinc in the seawater as the

inclusion of zinc in the coral is mostly due to the

The Adverse Impact of Anthropogenic Activities on Coral Reef

consumption of seawater-soluble metal through

respiration and coral polyp feeding. A high nickel

concentration, originating from fishing boats, crude

oil in oil production fields, and harbors associated

with organic matter, can significantly decrease the

survival of coral larvae. In Sipadan specifically, the

concentration of zinc in seawater is 0.070 ± 0.020 μ

g/L and the concentration of zinc in sediment is 13 ±

0.41 μ g/g, a low number compared to the

concentration elsewhere, but still concerning

(Mokthar et al., 2011).

3.1.5 Fishing and Overfishing

In Malaysia, nearly all citizens reside within 100km of

the coast and 53.4% of the fishers live in Sabah (Asian

Development Bank, 2014). In Eastern Malaysia,

destructive fishing practices have been prevalent, such

as cyanide usage in killing reef fish, which causes the

deterioration of valuable fish species like groupers,

snappers, and wrasses due to its lack of specificity. In

fact, about 68% of the coral reefs in Sabah have been

destroyed or harmed by cyanide, which is a

concerning number regarding the coral reef status

worldwide (Government of Malaysia, 2010).

The removal of herbivore species may be just as

impactful to the large-scale reef ecosystem as the

removal of predators. The algae will quickly take over

and dominate when marine grazers are eliminated,

this is especially true when the ecosystem is also

threatened by organic pollution and eutrophication.

As algae spread, the water's dissolved oxygen content

drops and sunlight is unable to reach deeper below the

surface, which results in the death of more underwater

organisms (El-Naggar and Hussein, 2020).

3.1.6 Tourism

Tourism increases the recreational constructions and

demand for services from the ecosystem.

Specifically, tourism related to coral reefs produces

35.8 billion dollars annually and draws almost 70

million visitors worldwide (Lamb et al., 2014).

Unmindful tourists may cause great harm to the coral

reefs during the scuba diving and snorkeling

processes, especially by inexperienced divers. Some

researchers show that there is a higher possibility of

coral-damaging actions, such as touching the coral

and kneeling on the coral, in inexperienced divers and

tourists, which may indicate a needed proficiency

level to get into contact with the coral is an

approachable solution (Lamb et al., 2014). Research

shows that around 90% of divers have one or more

contact with corals during their diving experiences,

with the most damage from accidental kicking of

corals when they lose their buoyancy (58%) (Barker

and Roberts, 2004).

Diving too close to the coral may unavoidably

cause some of the nearby sediments to be disturbed,

causing increased sedimentation loads from rocky

coralligenous assemblages that will lead to a

reduction in coral growth rate and health (Barker and

Roberts, 2004). This results in the abundance

decrease of massive corals and branch corals in diver-

heavy sites. In research conducted by Kalyan De and

Mandar Nanajkar, it is shown that the high-density

diving sights have a significantly higher amount of

coral damage than non-dive sites and low-density

diving sight, reaching an amount of 20% of the coral

being physically damaged by the year 2019 (Kalyan

et al.,).

3.2 Indirect Impact of Human Activities

3.2.1 Global Warming

Coral bleaching is one of the most direct

presentations of anthropogenic climate change’s

severe damage to a biological system, and global

warming is also the major threat that coral reefs are

facing currently. The symbiotic zooxanthellae depart

the coral skeleton during coral bleaching because the

algae are unable to adjust to the increasing

temperature. Without the symbiotic algae, the coral is

incapable of growing, feeding, and reproducing,

which eventually leads to death. If the environment

recovers to the normal level in time, then the

zooxanthellae will come back and the coral can

sustain. Therefore, there is research conducted to

evaluate the impact of anomaly exposure time and

magnitude of temperature change on the coral’s

ability to recover from anomalies (Strong et al.,

1996). This is measured using “degree heating weeks,”

or DHW, which is calculated using the formula DHW

= anomaly size-length of exposure. If DHW is greater

than 4, then the coral can recover from bleaching

without lasting damage. If DHW is greater than 8,

then the coral will bleach with a lasting impact,

causing possible mortality. If DHW rises above 12,

then it usually will cause mass destruction of coral

reefs, such as the mass bleaching incident in the

Western Indian Ocean in 1998, leading to the death

of 50% of the corals in the region (Strong et al., 1996).

3.2.2 Ocean Acidification

Ocean acidification is closely connected with the

rising concentration of CO2 across the world. It

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occurs when carbon dioxide enters water and creates

carbonic acid, which will then turn into bicarbonate

ions that will react with calcium carbonate, the main

composition of coral skeletons. Research in 1999

shows that the existence of high concentrations of

bicarbonate ions will be able to reduce up to 40% of

the coral and other marine calcifier’s ability to

produce calcium carbonate skeletons (Kleypas et al.,

1999). These factors will eventually lead to coral’s

inability to grow and sustain the reef.

3.2.3 Outbreaks of Crown-of-Thorns

Crown-of-Thorn is a species of starfish that typically

feeds on coral, causing a decrease in coral population.

Under natural processes, they can effectively control

the population of coral to maintain ecological

balance. However, outbreaks of crown-of-thorn

starfish may also lead to massive destruction of coral

reefs that would take 30-50 years to recover, and

maybe even longer considering the current ocean

acidification status. In worse cases, the coral reefs

may never recover as their habitat is being overtaken

by sponges, algal cover, or other coral species (El-

Naggar and Hussein, 2020).

The mass outbreaks of crown-of-thorn are

indirectly caused by humans as they thrive in poor

water quality and hazardous natural phenomena such

as tropical cyclones, which are increasing due to

chemical pollution and climate change. Moreover,

humans overharvest the crown-of-thorns’ natural

predator Triton Trumpet, which offers space and

opportunity for their population to thrive (Forbes,

2006).

4 SUGGESTIONS

4.1 Marine Protected Areas

Marine-protected areas can take different forms,

where some should restrict human entrance in general

and some can allow well-trained and professional

tourists to minimize the harm to the coral reefs, such

as in Sipadan. According to research conducted in

2019, the awareness of coral protection and quality

diving experience increases as the proficiency of the

diver increases, and the well-protected area will

further attract more experienced divers to maintain

the economy needed by the area (Barker and Roberts,

2004).

Sipadan has prohibited blast and cyanide fishers

due to concerns about overfishing and dynamite

fishing. However, by forcing these fishermen to

Mabuh Island, this action has caused more

devastation elsewhere. This shows that the marine-

protected areas are efficient in protecting the

biodiversity of a single area, but it is hard to apply to

a greater scale as socioeconomic needs still exist.

4.2 Funding of Different Action Plans

Currently, there are a variety of action plans in

Malaysia that are collected in Malaysia’s National

Plan of Action (NPOA), formed to inform all the

stakeholders to be aware of all the projects that are

undertaking actions. It includes 134 action plans,

headed by 16 government departments and agencies,

1 research institute, and 1 non-governmental

organization, that are either in progress or have been

submitted to appropriate agencies and organizations

(Asian Development Bank, 2014). However, these

action plans are suffering from multiple

implementation issues, including but not limited to

insufficient funding and inadequate permanent and

experienced experts. Therefore, only a few actions are

funded and commenced, while most of the action

plans remain proposed and unfunded (Asian

Development Bank, 2014).

5 CONCLUSION

Anthropogenic activities have impacted coral reefs

for years both directly and indirectly, causing

detrimental impacts to the reef ecosystem. Sipadan as

an individual diving site with a variety of precious

coral and fish populations is successful from its

control over divers and fishermen; however, its

strategy cannot be applied to a large scale due to

socioeconomic needs worldwide. The direct and

indirect interactions between humans and coral may

harm the coral from different aspects that vary by

species, limiting their growth, eliminating their

branches, and suppressing the chemical reactions

required. Due to the fast-paced destruction of coral

reefs, maintaining the current coral population is not

enough, restoration is also crucial to their survival;

therefore, the participation of different ocean

initiatives and actions needs to be noted by the mass

public. This paper gives a holistic view of the various

impacts of each anthropogenic action in depth and

can effectively inform the public about the correlation

between human activities and coral reef deterioration.

In the future, hopefully, there will be more research

conducted on the restoration process of coral reefs

and building coral reef resistance against global

warming.

The Adverse Impact of Anthropogenic Activities on Coral Reef

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