A tribute to Singapore's coral reefs. PART 1.
It's been a year and a half since I started this blog, which actually began as a personal
blog. But since my life practically revolves around coral reefs, diving and my work... well, you can see where I'm going with this. So this blog entry will be a tribute to the coral reefs that has given me so much since I started diving 4 years ago...Coral Reefs of Singapore
Singapore once consisted of over 60 offshore islands and patch reefs, most of which are situated south of mainland Singapore. Land reclamation combined with coastal development, which began in the 1960s, has since drastically changed Singapore’s coastlines and islands. Singapore’s 268km coastline has been extended seawards - especially on the eastern, northeastern and western parts of the island, while most of her southern islands were reclaimed, merging some islands to form larger ones in the process (Chou, 2001). Singapore’s current combined land area stands at about 690km2
, a >10% increase from her original size.
Singapore currently supports one of the world's busiest ports and one of the largest oil refining centers. However, this has not been without a great expense on Singapore’s natural resources, including her coral reefs. About 60% of the total coral reef areas in Singapore have been lost through foreshore reclamation (Chou, 1995; Chou & Goh, 1998). The reef flats of many islands e.g. Pulau Sudong, Pulau Hantu and Kusu Island were reclaimed right up to the reef slope. Many of the coral reef organisms were smothered by the reclamation, while others were severely affected by the resulting increase in water turbidity.
Characteristic thick layer of silt over our reefs
Results of the monitoring programme since 1987 show live coral cover of Singapore’s remaining reefs declining with both increasing depth and over time (Chou, 2001, data published on Coral Reef of Singapore
website). Hermatypic corals generally do not occur beyond the 6m depths due to the high sediment load and high turbidity in the water that restrict light penetration. Hermatypic corals have symbiotic zooxanthallae (algae), living within the coral tissues, which provide up to 90% of food for the corals through photosynthesis. Sedimentation rates ranged from 3 – 6mg cm-2
in 1979 but increased to 5 – 45mg cm-2
in 1994 (Low & Chou, 1994). The higher was value obtained from localised areas close to land reclamation projects. This reduced visibility from 10m in the 1960s to 2m or less today (Chou, 1996). As a consequence, the reef is very compact, as opposed to reefs in clear waters, which can be found at depths of 20m and more.
Rubble covered with silt - characteristic of Singapore's reefs as well. Seen here are also coral recruits (young/juvenile corals) indicating that there is still potential for our reefs to recover given the right conditions.
While live coral cover in most localities declined steadily, some localities have even suffered close to 100% loss in coral cover. This is attributed to their proximity to sedimentation-generating activities such as dumping of dredged spoils and reclamation respectively (Chou, 2001). According to Reefs at Risk (2001), Singapore’s reefs cover an approximate area of 54km2
. However, this figure is now thought to be an over-estimation and that the actual combined reef area left in Singapore is actually less.
Despite this loss in live coral cover, our reefs still support rich marine life. Singapore’s reefs still harbour 197 species of hard corals from 55 genera, comparable to nearby reefs of Thailand, Philippines and Malaysia (Lim & Chou, 1991). This is quite encouraging if one were to compare the extensive reefs found in the region and the size of the remaining reefs found in Singapore. This is probably due to Singapore’s locale: we are situated in southeast Asia and near the ‘Coral Triangle’, an area known to have the world’s highest coral reef biodiversity (Allen, 2000).
Reefs of P. Hantu (2006) Reefs of P. Jong (2005)
Our reefs also still support over 20 species of soft corals, 130 species of fishes from 30 families, 250 species of mollusks, 30 species of echinoderms, 30 species of algae and over 800 species of crustaceans (Shoo, 2004; Chou & Tun, unpublished data). In addition, new records of various organisms have recently been discovered in Singapore waters.
Doryrhamphus janssi. New record of pipefish found on reefs of P. Jong in Nov 2005. Amblyleotris pariophthalma. New record of goby found on reefs of P. Hantu in Feb 2006.
Numerous new records of nudibranchs, or more commonly known as sea slugs and much loved by divers worldwide, are being found on the reefs around Pulau Hantu. There have also been new records of fishes found just in the past year (2005) alone, and a suspect new record for hard corals. These new records suggest that there is still much not known of Singapore’s reefs that holds hope for these gems in our own backyard.References
Allen, G.R. 2000. Indo-Pacific coral-reef fishes as indicators of conservation hotspots. Proceedings of the 9th International Coral Reef Symposium, Bali, Indonesia.
Chou, L. M. 1995. Effects to conserve Singapore marine and coastal ecosystems. Malaysian Institute of Maritime Affairs (MIMA) Seminar, March 1995.
Chou, L. M. and Goh, B. P. L. 1998. Singapore coral reefs – balancing development and conservation. In: B. Morton (Ed.) Marine Biology of the South China Sea, Proceedings of the Third International Conference on the Marine Biology of the South China Sea, 28 Oct – 1 Nov 1996, Hong Kong. Hong Kong University Press, pp. 355-368.
Chou, L. M. 2001. Country report: Singapore. International Coral Reef Initiative (ICRI).
Low, J. K. Y. and Chou, L. M. 1994. Sedimentation rates in Singapore waters. Proceedings of Third ASEAN-Australian Symposium on Living Coastal Resources 2: 697 – 701.
Shoo, J. 2004. Investigating the biodiversity of coral reef in southern islands of Singapore. BSc dissertation, Department of Biological Sciences, National Univesity of Singapore.