Sustainability at Sea – Conservation of Singapore’s Reefs Part 1 of 2

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Sustainability at Sea – Reefs of Singapore

The health of marine ecosystem is critical to sustaining life on the planet. Oceans need to be protected and managed as they provide food and livelihood to millions of people; serve as habitat for wide range of species; and govern the planet’s climatic systems. Sadly, for years, human activities have been affecting the marine environment, whether through bad fishing practices, pollution or illegal dumping. In this edition of Sustainability at Sea, we will explore the reefs of our local waters and the threats that it faces.

Reef Diversity in Singapore (Click for Source)

Singapore’s Reef Diversity

Singapore has had a mixed history when it comes to reefs and other marine ecosystems. Singapore has about 600 km2 of sea, with about 9.5 km2 of coral reef, 6.26 km2 of Mangroves, and about 5 km of mud flats (Source). The island sits in a global hotspot of coral reef diversity. It was found in recent surveys that the island contains more than 255 species of coral, belonging to 56 genera (Source). That is half as much as the entire Great Barrier Reef, and nearly 3 times as many as live in all of the Atlantic Ocean! Singapore is also home to many species of fish, sharks, sea turtles, nudibranchs, and other important and unique species. 

These areas, especially the coral reefs, are valuable to the local economy for tourism, food, medicine and other resources. These ecosystems provide food and protect our small island nation from erosion during major storms. Although the seas here are incredibly valuable and diverse, they are also highly threatened.

The reefs with the highest levels of coral diversity are those around Raffles Lighthouse (Pulau Satumu) with 151 coral species from 50 genera. This area is the furthest island from the Singapore mainland, and so is not as impacted by pollution and sedimentation from the population centers. But, the island is also a defacto Marine Protected Areas (MPA) – See below for more. Because the island has a lighthouse, it is illegal to land a boat there without permissions, and diving is also restricted around the island (Source).

Although this protected area was not established for the benefit of marine life, it is having that effect. In surveys conducted by Dr. Huang in 2009 (Source), they even found a species of coral (Stylophora pistillata) at Raffles Lighthouse that had not been seen in Singapore waters since the 1960’s and was thought to be locally extinct. As we move closer towards the mainland from Raffles Lighthouse, we see a decreasing abundance and health of the corals due to the effects of the dredging, busy harbors, and human activities on land.

Sungei Buloh Wetland Reserve (Click for Source)

Reef Status of Singapore

Singapore is a growing nation, and some of that growth has come at a major cost to the marine environments. The land reclamation and destruction of more than 80% of the mangroves bordering the island has led to high levels of sedimentation on the reefs (Source). Sediment consists of mud, sand, and soils that causes direct stress to the corals and also blocks out much of the light that they need to grow. This has reduced the size of reefs, the depths to which they can grow, and the number of species present. Unfortunately, in the 2009 surveys by Huang (Source), it was found that 94 species of corals found here in the 1960’s can no longer be found today.

These findings highlight an urgent need for more protections and active conservation measures such as the restoration of reefs. While Singapore still has around 10 square kilometers of reef, less than 1% of it is currently under protection, far less than the global average of 32% The rest of the area is covered under an Exclusive Economic Zone (EEZ). It is important to remember EEZs and Marine Protected Areas do not necessarily exclude all economic activities.

Marine Protected Areas

Marine Protected Areas (MPAs) are a major way that countries around the world preserve their marine ecosystems and resources for generations to come. In total, around 32.2% (Source) of the world’s reefs are under protection, protecting them from developers, fisherman, and other extractive uses that would endanger their health or biodiversity. It also means that certain rules are in place about who can use these areas for financial gain. For decades MPA designation has been the leading method of conservationists, however as global factors like climate change become a larger threat the effectiveness of MPAs is being called into question. But, they are still the most common first step towards real change in the way marine areas are managed by countries.

Marine Protected Areas Around the World (Click for Source)
Benefits of Marine Protected Areas (Click for Source)

Recent Development – Sisters’ Islands Marine Park

In 2014, Singapore set aside an area to be its first MPA, the Sisters’ Island Marine Park (SIMP), which became law in 2017 (Source). This park is designed under the guidelines that any activities which threaten biodiversity are prohibited, but educational, scientific, and recreation activities are still allowed. This action taken by Singapore is a welcomed and encouraging first step. However, much more needs to be done to further the goal of protecting our reefs.


Marine Park Areas of Singapore (Click for Source)

Threats to our Reefs

In this section, we will explore the threats that reefs are facing both locally and globally.

What is Coral Bleaching? (Click for Source)

What is Coral Bleaching?

Coral Bleaching is what occurs when the sea waters get unseasonably hot. Like us, corals have a narrow internal temperature range in which they are able to survive. But, unlike us they cannot regulate the temperature inside their bodies. Inside every coral there are millions of living unicellular algae called zooxanthellae. These work like the leaves on a tree to capture sunlight and produce energy. But, when the temperature inside the coral increases by 1-2° Celsius, the algae are can no longer do their job, and are lost. This leaves the coral looking brilliantly white, which is where the term ‘bleaching’ comes from. When the corals are bleached, they are not getting food, and many will perish. These bleaching events are becoming more frequent and severe globally as the planet warms.

Coral Diseases and Ocean Acidification

Coral diseases and ocean acidification are other symptoms of climate change. Disease outbreaks occur due to excess nutrients and pollution, but also because of stress. As conditions change in the ocean the corals become more stressed and diseases are able to overtake them. Diseases have led to the loss of about 90% of corals in the Caribbean, and are spreading throughout the Indo-Pacific as well (Source).

Ocean Acidification occurs when water warms up and absorbs more carbon dioxide from the atmosphere. The carbon dioxide in the water forms carbonic acid, and dissolves the very skeleton of the corals, clams, and other ocean creatures. These leaves the existing reef structure weakened, and prevents new coral larvae from successfully settling down.


Coral Disease in Caribbean corals (Click for Source)

Sedimentation through Land Reclamation

Singapore has been undertaking major projects to expand the island and protect its shores from storms and rising seas. This reclamation and island building has led to very high levels of sedimentation on the reefs (Source). Sedimentation occurs as small particles of sand and mud flow into the sea or are disturbed by dredging. This sediment blocks out the light in the water, preventing corals from growing. Furthermore, it covers and stresses the corals out as they need to use their own energy to produce mucous to remove the sediment. In the worst cases, the reef is buried in sediment and lost forever. 



Singapore's Reclaimed Land (Click for Source)


The coral reefs of Singapore are heavily threatened by both global and local threats, and are being depleted rapidly. Although we can all readily see these problems, there is also a lot going on to reverse this damage and save the seas around Singapore. In the next article, we will look at some of these methods and efforts as well as propose some to protect our local reefs.