Course:EOSC270/2023/Group 1 - Reef Degradation and Restoration in the South China Sea

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Contextual Background & Causes

The South China Sea is a hotspot for destructive human activities.[1] While processes such as artificial island building and mining are beneficial to the resources and industries of countries like China, the main perpetrator, they also degrade coral reefs.[2] This was recognized in 1994 and in 2003 Hong Kong, and subsequently the Chinese government at large, began the ongoing process of coral restoration by deploying artificial coral reefs. These are non-living structures, made to resemble real reefs, that provide a habitat to be colonized by photosynthetic organisms, fish, and marine invertebrates- including new coral.[3] However, coral reef degradation is still occurring at an unmanageable rate, heralding a greater need for artificial reefs and other effective solutions to protect marine ecosystems.

The South China Sea

The South China Sea borders the Southeast Asian mainland. The major feature of the sea is a deep basin located in its eastern section, with reef covered shoals rising into the southern portion. Monsoon’s control the surface currents where water is relatively warm, ranging from 21 to 27°C.[1]

Figure 1: Overfishing greatly destabilizes South China Sea reef ecosystems. Red marks indicate areas where fishing has outpaced the capacity of fish populations to recover.

The sea itself is the subject of major geopolitical and economic interest for the 6 sovereign states that border its waters due to large reserves of natural oil and gas located in the southern regions and its strategic military positioning.[4] The off-shore reefs in particular have complex overlapping sovereignty claims, which have resulted in a large military presence in the area. The military expansion of each of these sovereign nations (with China’s reclamation far outpacing those of the other claimants) into the sea has resulted in the development of artificial islands that total an area close to 3000 acres.[5]

Major causes of coral degradation

Coral reefs in the area were already under heavy stress due human practices which have persisted into the period of geopolitical tension.[4]

China’s fisheries are important to ensure food security for its growing population. Estimates project that by 2030, the expanding middle class in China will account for 38 percent of global fish consumption. This and loose fishing laws passed by China in the 1980’s has resulted in overfishing and a rapid depletion of fish stocks in the South China Sea. The South China Sea alone accounts for 16.6 MMT of catch per year, and fishing stocks have plunged over a third over the past 30 years, and is estimated to fall further 59 percent by 2045.[2] Figure 1 shows the geographic extent of overfishing.

Overfishing is done through exploitative fishing practices, both legal and illegal. Fish are being killed using dynamite, which physically destroys reefs.[1] There is also the use of cyanide spray to stun and capture fish for live fish trading and aquariums, which can cause coral bleaching.[6] Many other activities are compounding coral reef degradation.[4][7][6][1][2] For example, mining and hydrofracking provide sources of oil, gas, and minerals for industrialization while destroying reefs. These practices are often done by dredging, a form of excavation that also contributes to increased turbidity and disturbs seafloor organisms. Other negative human impacts are militarization and transportation, construction (of ports, airstrips, artificial islands, etc), and pollution from urban waste and agricultural runoff.

Impact on the South China Sea

Impacts of coral reef degradation on the South China Sea

Offshore coral communities have been recognized as one of the key systems present in the South China Sea, so their degradation negatively impacts the sea.[6] Coral reefs are filled with resources that preserve coastline stabilities.[8][5] Evidence showcases that a decline in coral reef ecosystems would prevent coastlines stability, causing coastal erosion.[8] This would also result in a decline calcium carbonate production.[7] Calcium carbonate is important for forming hard shells and skeletons for organisms like coral and mussels. Without this compound, these organisms may not survive, causing an ecosystem destabilization that impacts the South China Sea negatively.[9]

What are the unique characteristics of the South China Sea that make it vulnerable to coral reef degradation?

The South China Sea inhabits approximately 600 coral species across 12,000 square kilometers. [7][1] This diversity attracts tourists, introducing another way for humans to damage the coral reefs.[5]

Figure 2: Coral reef biodiversity available before (left), and after (right) damage done by militarization.

The low financial situations amongst coastal communities causes more individuals to engage in overfishing.[5] The activities conducted during overfishing cause damage to the coral reef biomass, and these issues increase in correlation to lower-income communities.[1]

The overlapping jurisdiction conflicts are halting coral reef restoration attempts. This conflict causes coral reef restoration to become unprioritized, as countries are focused on militarization and construction.[1] By doing so, countries are contributing to coral reef damage, as opposed to restoring the damage.

What organisms does coral reef degradation impact?

The organisms directly impacted are the coral reefs, causing a decrease in their biodiversity (Figure 2).[7] The coral reefs provides structural services, as they act as buffers against storms and waves, providing coastal protection. Biotic services are provided due being a food source. Damage to them causes other marine organisms, such as crown-of-thorns starfish, bottom-dwelling organisms, herbivorous fish, and migratory fish to be indirectly impacted.[5][7] The coastal communities also rely on the coral reefs, as they exploit the resources to sustain their lifestyles, so damage to them causes humans to be indirectly affected.[6][7]

How and why does it impact these organisms?

Figure 3: Crown-of-thorns starfish (CoTS) sample in the South China Sea.

The coral reefs in the South China Sea contain about 20% of Asia’s coral reefs. They have the highest biodiversity in terms of coral species, fish and much more. However, due to anthropogenic practices as mentioned before, about 90% of these reefs are categorized under ‘high risk’ for severe decline of coral population.[10]

Due to the political tensions between South China and Vietnam, a lot of increase in industrial activities such as nuclear and steel manufacturing is seen. This produces approximately one million metric tonnes of toxic waste such as naphthalene and uranium, which then dissolves, causing respiratory paralysis in many organisms that use coral reefs for shelter and feeding grounds. The waste produced also causes heat-waves, creating a warmer environment  which can destroy marine habitats and reduces the ability of many coral to pollinate, thereby reducing their population.[11]

Unique characteristics that cause coral reefs to be vulnerable to degradation

The perfect balance between the coral reefs and the environment helps ensure the ecosystem thrives. However, coastal development and poor land-use practices have directly contributed to creating a highly toxic environment with harsh environmental temperatures. This has provided the conditions for an immensely dangerous crown-of-thorns starfish (CoTS) outbreak to take place.[11]

During the past few decades, scientists have observed that CoTS can eat approximately 90% of live coral. They consume corals by extruding their stomach enzymes onto the reefs, devastating the biodiversity around it.[12] The enzymes produced reduce the calcium carbonate level and destabilizes the reefs physical structure while deteriorating the surrounding habitat.[10]

Attempts at Restoration: Artificial Reefs

What are the measurable ecosystem changes that have occurred?

Figure 4: Variance of phytoplankton biomasses through 2007-2009.

Degradation of coral reefs is now putting an adverse strain on the South China Sea ecosystems. To remedy this, artificial reefs have been tried in recent years to reduce the detrimental effects of coral deterioration. Artificial reefs have been used in the South China Sea since they were first constructed in May 2003. A study was conducted on how artificial reefs assisted in the recovery of marine ecosystems. The artificial reefs were constructed between May of 2003 and December of 2007, and this data was compared to the short-term deployment of artificial reefs in 2009. Phytoplankton is an essential element of marine ecosystems and an excellent indicator of an ecosystem's health. To evaluate the performance of the artificial reefs, phytoplankton biomasses were graphed in this study.[13]

Figure 5a: Graph of Publications of artificial reefs over the last few years (left)
Figure 5b: Image of artificial reef planted in the Netherlands (right)

The results showed that the biomass of phytoplankton increased significantly after the placement of artificial reefs. As shown in the table, there was an increase in the richness of 198 phytoplankton cells between 2007 and 2009, along with higher concentrations of cyanophytes, diatoms, and Dinophyceae. In summary, the 2008 spike in phytoplankton biomass and richness of diversity of phytoplankton species was a result of the artificial reefs.[13]

What is the present status compared to the past?

As established, over the past few decades, human impacts have harmed the coral reef environment in the South China Sea. However, using artificial reefs is now a terrific approach to lessen the impact on marine life. Artificial reef science study has grown in popularity during the past few years. This graph shows the publications related to artificial reefs that have been published during the past few years, demonstrating an exponential growth in study. As a result, we are much more aware of the value of artificial reefs for marine ecosystems today and can take advantage of their use.[14]

Figure 6: Graph depicting potential trajectory for coral reef ecosystems in South China Sea.

What is the prognosis for the future if we continue on our current trajectory?

Restoration of coral reefs has been shown to benefit marine ecosystems over time, including biomasses of phytoplankton and other epipelagic species. This is also because coral reefs function as habitats for many juvenile organisms. The need for restoration is a result of both the escalating effects of global warming and the consequences that industry has had on the South China Sea region. Rising sea levels are just one of the many detrimental effects of global warming. Increased sedimentation in coral reef ecosystems is a result of sea level rise. Among other detrimental effects, this causes coral reef ecosystems to suffocate. This figure shows the comparison between a prospective ecosystem with and without mitigations against global warming in an effort to examine the potential trajectories connected with such consequences. The red line in the figure, which extends past the ideal dotted line for coral reef growth, depicts the exponential rise in sea level.[5]

Other Solutions to Coral Degradation

Local-scale Solutions

Coral reef restoration by artificial reefs is a costly and labour-intensive process that is not well-suited for application in large areas. Therefore the most important strategy for restoring the South China Sea coral ecosystems should still be conservation and protection. However, severe degradation of coral reefs means that reef restoration techniques are unavoidable if we want to preserve these unique and diverse ecosystems.[15]

Marine Protected Areas

Marine protected areas (MPAs) are areas designated for the protection of the local marine environment. Within their boundaries, regulations prohibit fishing and any potentially destructive human activity, enforced by authorities and police. When successfully managed, MPAs establish more sustainable fisheries and tourism practices, and bring benefits to the local economy. The use of MPAs for the conservation and protection of marine environments have been on the rise, but with more locations designated and better enforcement, their positive benefits can still grow.[16]

Artificial Reefs

In addition to the direct effects outlined above, artificial reefs can provide many other beneficial outcomes for the restoration of reef ecosystems. These can include the diversion of human activity away from natural reefs, connecting natural reefs to allow better recovery, serving as restoration research and testing locations, and more.[17]

Coral Transplantation

The transplantation of live coral specimens to sites requiring recovery is a widely accepted method for restoration. When implemented correctly, this method can boast survival rates of up to 95%[15], immediate increase in coral cover, as well as the reintroduction and/or survival of the most at risk species. At some locations, the transplantation of entire coral colonies are done to develop a reef. For smaller-scale projects, fragments of coral are brought in to allow for natural regeneration.[17]

International Solutions

While international cooperation is desirable for the resolution of the complex issues in the South China Sea region, this does not come so easily in a region fraught with tension and disputes. The six sovereign states surrounding the South China Sea all have various overlapping claims in the water body. Furthermore, their conflicting interests and an increasing military presence hinder cooperation on environmental issues.[5]

International Collaboration

Ideas similar to a “Greater Spratly Islands Peace Park” have been proposed numerous times by different entities. The Park, covering most of the South China Sea, would take the form of a network of MPAs administered independently, but collaboratively, by each nation, or a transboundary marine preserve overseen by an intergovernmental organization. This kind of establishment would contribute significantly to the conservation of the marine environment and the sustainable development of neighbouring communities.[5][18]

Arbitration of Disputes

The South China Sea Arbitration was an arbitral case concerning China’s actions in the South China Sea. This arbitration is of particular importance in this region for the use of a science experts panel and its clarification of marine environmental protection obligations under the United Nations Convention on the Law of the Sea.[19] This case sets the precedent for any future disputes in the South China Sea region, regarding environmental obligations or territorial claims, to be settled through arbitration by a global institution.


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