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Singapore, officially the Republic of Singapore, population 4.35 million (June 2005) is an island city-state and the smallest country in South-East Asia. Singapore consists of 63 islands, including the main island itself. It is located on the southern tip of the Malay Peninsula, south of the Malaysian state of Johor, and north of the Indonesian Riau Islands. It lies just 137 kilometres (85 miles) north of the Equator.

Singapore has reclaimed land with earth obtained from its own hills, the seabed and neighbouring countries. As a result, Singapore's land area grew from 581.5 square kilometres (224.5 sq mi) in the 1960s to 697.2 square kilometres (269.1 sq mi) today, and may grow by another 100 square kilometres (38.6 sq mi) by 2030. About 23% of Singapore's land area consists of forest and nature reserves.

Coastal and Marine Ecosystems

The coastal and marine ecosystems of Singapore are very limited and modified by development and the port industry, which is one of the biggest income-earning businesses in the country. Port limits extend to almost all the entire territorial waters, and reclamation has transformed almost the entire southern and northeastern coasts of the main island considerably (Chou 1995).

The steep beach front along the southeastern coast was once composed of sandy beaches and mudflats. Original rocky shores are found mainly on the southern offshore islands and small parts of the northern coast. Around 22 km2 of mangroves (or less than 1% of the original mangroves) remain in Singapore and none are protected (MacKinnon 1997), except for 87 ha at the Sungei Buloh Wetland Reserve. These are confined to isolated patches on the northern coast and northern offshore islands of Pulau Ubin and Pulau Tekong, and the eastern shore of Pulau Semakau in the south. The mangroves of Pulau Semakau were initially cleared to make way for Singapore’s offshore landfill. A massive replanting project was undertaken to maintain the ecosystem and mangroves were replanted on the western shore of the island. Seagrass meadows can be found in various areas but most notably on the extensive reef flats of the Cyrene reefs, west of Pulau Semakau and off Pulau Ubin.

There are currently no specific laws for the protection of mangrove forests and existing seagrass meadows (ICRI 1997). At present, there are no MPAs in Singapore although three areas are protected to some extent. The first is the 87 ha Sungei Buloh Wetland Reserve located along the northern coast of the mainland. It is a coastal mangrove habitat. The second is the Labrador Nature Reserve, a 16 ha area of natural rocky shore and coastal hill forest located on the southern coast of the mainland. Labrador was officially designated a Natural Reserve in 2002. The third area comprising the Sisters’ Islands is located south of the mainland and is considered a Marine Nature Area.



Seagrasses of Singapore

Seagrass meadows in Singapore play a vital role in supporting coastal marine communities and in maintaining diverse flora and fauna. They are an important component of coastal fisheries productivity and they play an important role in maintaining coastal water quality and clarity. The seagrasses of Singapore are also important food for marine green turtles and dugongs.

There are 11 seagrass species found in the country: Cymodocea rotundata, Cymodocea serrulata, Enhalus acoroides, Halodule pinifolia, Halodule uninervis, Halophila beccarii, Halophila minor, Halophila ovalis, Halophila spinulosa, Syringodium isoetifolium and Thalassia hemprichii (Spalding 2000). Seagrasses were reported to be common between late 1950's and the early 1970's on reef-flats and the intertidal zones at Kranji and West Johor Strait (Chuang 1961; Johnson 1973). Loo et al. (1996) reported seagrass at Changi beach and Beting Bemban Besar (patch reef). Other studies reported the presence of seagrasses from locations south of the main island of Singapore which included Pulau Hantu, Pulau Semakau, Terumbu Raya (patch reef) and Hantu West (patch reef) and in the north, Pulau Tekong (Hsu and Chou, 1989a,b).

Recently, another species of seagrass was added to the list. A patch of Halophila decipiens was found in the waters off Pulau Semakau at a depth of about 8m, by Eugene Goh, who was diving off the island late 2007. A specimen was collected and passed on to the National Biodiversity Centre. It has since been verified and lodged with the Singapore Herbarium. It has since been sighted at other locations in the waters of Southern Singapore.

For detailed information on the Seagrasses of Singapore, click here for review of current knowledge.




Chek Jawa (Pulau Ubin)


Monitoring: ongoing

Principal watchers: Team Seagrass
Location: shallow lagoon on north east shore of Pulau Ubin
Site code: CJ1, CJ2

CJ1 position: N1.40991 E103.99235 (heading 95 degrees)

CJ2 position: N1.41249 E103.99299 (heading 95 degrees)

Best tides: <0.2m
Issues: marine debris/litter, coastal development, land reclamation, land runoff
Comments: Tanjong Chek Jawa is a cape and the name of its surrounding areas located on the south-eastern tip of Pulau Ubin. Pulau Ubin is a small island (10.19 km2) situated in the north east of mainland Singapore, to the west of Pulau Tekong. Granite quarrying supported a few thousand settlers on Pulau Ubin in the 1960s, but only about a hundred villagers live there today. It is also one of the very few off-shore islands in Singapore that is still inhabited.

The 1020-hectare island was once a cluster of five smaller ones separated by tidal rivers, but the building of bunds for prawn farming has since united these into a single island. Two other islets, Pulau Ketam (Crab Island) and Pulau Sekudu (Frog Island), lie to its south. Pulau Ubin is one of the last areas in Singapore that has been preserved from urban development, concrete buildings and tarmac roads. Pulau Ubin's wooden house villages and wooden jetties, relaxed inhabitants, rich and preserved wildlife, abandoned quarries and plantations, and untouched nature in general make it the last witness of the old "kampong" Singapore that existed before modern industrial times and large scale urban development.

Located at the eastern tip of Pulau Ubin, Chek Jawa is a collection of six distinct habitats - coastal forest, mangroves, sand bars, seagrass lagoon, rocky shore & coral rubble.

Slated for land reclamation in 1992, the wonderful secrets of Chek Jawa were unveiled only in December 2000. As public attention was drawn to this site, thousands of Singaporeans flocked to visit this wetland treasure. At the same time, appeals from nature lovers and the general public led to a review of its reclamations plans. After carefully considering all public submissions and extensive consultations with scientific experts and relevant government agencies, it was announced in 2001 that reclamation works would be deferred as long as Pulau Ubin is not required for development.

Status (Jun13):

  • Seagrass cover is generally between 25 and 65%, and is slightly higher at CJ1 than CJ2.
  • The long-term trend in abundance suggests the meadow abundance has stabilised, after
    increasing in 2007-2008.

  • A seasonal trend in seagrass abundance is apparent at both sites, with higher abundances from April to June, and lower abundance October to December.

  • Eight seagrass species are found at Chek Jawa: Halophila beccarii, Halophila spinulosa, Cymodocea rotundata, Halophila ovalis, Halophila minor, Halodule uninervis, Thalassia hemprichii and isolated clumps of Enhalus acoroides.
  • Site CJ1 has been mainly dominated by C. rotundata since monitoring commenced, but from Jun08-Jun11, the abundance of Halophila spinulosa increased across the meadow. Species composition has fluctuated greatly at CJ2, but has been dominated by Halophila species.
  • Canopy height is greater at CJ1 as the site has a high composition of C. rotundata. Although H. ovalis dominates CJ2, canopy height is driven by the H. uninervis present.

  • Macro-algal abundance is similar at both sites (25-30% on average) and fluctuates greatly within and between years. Patterns in epiphyte abundance are similar between sites, however the amplitudes differ. Epiphytes were higher at CJ2 in 2008, however abundances are now slightly higher at CJ1. Epiphyte abundances has increased at both sites since 2010. Whether this is natural fluctuations or a consequence of elevated nutrients is currently unknown.






Cyrene Reef


Monitoring: ongoing

Principal watchers: Team Seagrass
Location: Patch reefs within harbour, south of mainland Singapore
Site code: CR1, CR2

CR1 position:

CR2 position:

Best tides:
Issues: marine debris/litter, coastal development, land reclamation, land runoff

Comments: Cyrene is comprised of 3 patch reefs- Terumbu Pandan, Pandan Beacon and South Cyrene Beacon,and is one of the largest patch reef systems in Singapore. Cyrene Reef is a key maritime crossroad where east-west traffic routes cross north-south routes. Approximately five hundred ships transit the waters around the reef every day. The reef is also next to massive industrial sites like Jurong Island and Pulau Bukom, and opposite Singapore's container terminals. With abundant seagrass meadows and other marine life, Cyrene is a natural wonder. The reef top meadow is a mixture of Enhalus acoroides, Cymodocea serrulata, Cymodocea rotundata, Halodule uninervis, Halophila ovalis, Thalassia hemprichii and Syringodium isoetifolium.

Status (Jun13):

  • Seagrass abundance long-term trend for the location appears stable, however there are
    differences between the sites.
  • Seagrass abundance increased at CR2 in 2011-12, but this appears a consequence of
    increasing abundance of Halophila ovalis. As Halophila ovalis is an early colonising species,
    this may suggest an increased level of disturbance (e.g. sediment movement, wave action) at
    the site.
  • Seagrass abundance at CR1 decreased although composition of Thalassia hemprichii
    appears unchanged. Cover also appears to show a seasonal trend, with increases Mar-May,
    and decreasing until late in the year.


  • Seagrass canopy height has decreased at both sites over the long-term.

  • Macroalgae abundance has decreased slightly at CR1 over the long-term, but has remained relatively stable at CR2. Epiphyte cover has similarly decreased over the long-term at CR1 and remained relatively stable at CR2.







Monitoring: ongoing

Principal watchers: Raffle's Girls School, Team Seagrass and NParks
Location: rocky reef, southern part of the main island of Singapore
Site code: LP
Issues: marine debris/litter, coastal development, land reclamation, land runoff

Comments:  Labrador Nature Reserve, also known as Labrador Park. It contains the only rocky sea-cliff on the mainland that is accessible to the public for recreation, education and scientific research. Since 2002, 10 hectares of coastal secondary vegetation and its rocky shore have been gazetted as a Nature Reserve.

Labrador Nature Reserve has a rich variety of flora and fauna. More than 50 species of birds and more than 11 species of butterfly have been recorded. In addition, the rocky shore contains a multitude of corals and crabs, seagrasses (Halophila Ovalis, Thalassia Hemprichii, and Enhalus Acoroides), sandworms and horseshoe crabs. The Common Hairy Crab (Pilumnus vespertilio) is often spotted in the area

Status (Jun13):

  • mean total seagrass abundance has decreased between 2007 and 2012, however due to limited available data, the trend cannot be investigated.
  • Site LP2 has also been examined over the last couple of years, however, data is similarly unavailable to examined trends or condition.


  • In 2007 only two seagrass species were present (Enhalus acoroides and Halophila ovalis), however in 2012 four species were reported, the additional species including Thalassia hemprichii and Syringodium isoetifolium


  • With a limited dataset, it is not possible to examine trends is abundance of macroalgae or epiphytes.






Pulau Semakau

Monitoring: ongoing

Principal watchers: Team Seagrass
Location: fringing reef platform on western shore of island
Site code: PS1, PS2, PS3

PS1 position: N1.21344 E103.75809 (heading 285 degrees)

PS2 position: N1.21108 E103.75772 (heading 285 degrees)

PS3 position: N1.20837 E103.75714 (heading 285 degrees)

Best tides: <0.3m
Issues: marine debris/litter
Comments: Pulau Semakau is located to the south of the main island of Singapore, off the Straits of Singapore. Pulau Semakau is Singapore's first offshore landfill. Semakau Landfill is filled mainly with inert ash produced by Singapore's four incineration plants, which incinerate the country's waste, shipped there in a covered barge (to prevent the ash from get blown into the air) every night.

Semakau Landfill was formed by the amalgamation of Pulau Sakeng with the eastern half of Pulau Semakau. The western half of Pulau Semakau was left natural, unaffected by the landfill construction, and this is where the seagrass monitoring sites are located.

Vast tracts of Enhalus acoroides fringe the island, stretching for kilometres. Pulau Semakau is one of the few places in Singapore where Syringodium isoetifolium occurs in abundance.

Status (Jun13):

  • Seagrass cover is significantly lower at PS1 than the other sites, and has remained low since monitoring was established. Seagrass abundance at PS1 varies between 8-18% on average.
  • PS2 and PS3 decreased in abundance in late 2008 (18 months after being established). Since 2008, abundance have changed little, varying between 15-40%.
  • Although seagrass abundance has declined over the long term, there has been little decline since 2008 with abundance remain relatively stable between years. Within years, a seasonal trend in abundance is apparent, with higher abundances Mar-May, and lower from Aug-Dec.

  • There appears a transition in species composition between the sites, from Enhalus to Cymodocea dominating, from PS1 to PS3 respectively in the period prior to 2009.
  • Species composition appears to fluctuate, primarily a consequence of the composition of Halophila ovalis or Cymodocea serrulata. The decline in composition of C. serrulata corresponds with the decreasing abundance. In 2009-2010 the composition of Si also increased at PS2.

  • Canopy height has not changed greatly over the monitoring period, and canopy heights are representative of the change in species dominance between sites.


  • The Pulau Semakau epiphyte long-term average is 43% and epiphyte abundance is seasonally higher in Sep-Nov of each year.
  • The Pulau Semakau macroalgae long-term average is 30%. Macroalgae has differed between year, decreasing at PS2 and PS3 in 2011 and at PS1 in 2012. Within years, macroalage is seasonally higher in Aug-Nov of each year.







Principal watchers: Team Seagrass
Location: Fringing reef platform
Site code: SE1

SE1 position:

Best tides: <0.2m

Seagrass: Halophila Ovalis and Enhalus Acoroides
Issues: marine debris/litter, coastal development, land reclamation, land runoff
Comments:Sentosa, which means peace and tranquility in Malay, is a popular island resort in Singapore, visited by some five million people a year. Attractions include a two-kilometre long sheltered beach, Fort Siloso, two golf courses and two five-star hotels.

Status (Jun13):

  • Prior to July 2009, seagrass cover did not vary greatly between years, although a seasonal pattern may be apparent with years, with lower abundance later in the calendar year. In August 2009, seagrass abundance declined, however whether it has improved since is unknown.

  • The site is dominated by Halophila ovalis, however in 2008, the abundance of H. ovalis declined for 6 months, during which period Enhalus acoroides dominated.

  • Enhalus acoroides canopy height has changed little over the monitoring period.

  • Macroalgae cover is generally between 10 - 30% on average. There is a significant (p<0.05) inverse relationship between epiphyte cover and macroalgae cover (i.e. epiphyte increases when macroalgae decreases).






Principal watchers: Schering Plough staff
Location: Narrow coastal shoreline directly in front of Schering Plough
Site code: TU1

TU1 position:

Best tides:

Seagrass: Halophila Ovalis and Enhalus Acoroides
Issues: marine debris/litter, coastal development, land reclamation, land runoff

Comments:  Tuas is largely an industrial zone located in the western part of Singapore. The Tuas Planning Area is located within the West Region, and is bounded by Tengah Reservoir to the north, Strait of Johor to the west, Straits of Singapore to the south, and the Pan Island Expressway to the east.

Status (Jun13):

  • Seagrass cover is moderate along the shore, although patchy. Current status is unknown.
  • The only species present is Halophila ovalis.







All images courtesy of Team Seagrass and Seagrass-Watch HQ



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