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Marine Biology Lab

Coral Reefs In Singapore
There were once over 60 offshore islands and patch reefs around Singapore, most of which were situated south of mainland Singapore. However, since the mid 1970s, major land reclamation was carried out on the mainland as well as the offshore southern islands. Most of the southern islands were reclaimed, adding 1695 ha to Singapore's total land area. Some islands were merged as a result. 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. Since 1986, most coral reefs in Singapore have lost up to 65% of their live coral cover.

Life on our reefs
Contrary to the belief that our reefs have been permanently devastated, they still support rich marine life. The reefs in Singapore harbour close to 200 species of hard corals from 55 genera, which given the size of the reefs and conditions present here, compare favourably with coral species richness in the more extensive reefs of the region. Singapore reefs sustain good diversity of other marine organisms too, such as gorgonians (Goh et al 1997) and nudibranchs. So far, 111 reef fish species from 30 families were also recorded.

Threats to Singapore reefs
The most significant cause of reef degradation in Singapore is sedimentation. Land reclamation, dredging of shipping channels and dumping of earth spoils, have increased the sediment load. Loss of coral reefs to land reclamation occurred along the southwest coast of the mainland and on some of the offshore southern islands. Increased sedimentation affected the remaining reefs in two ways 1) by causing a slow but steady reduction in live coral cover 2) by reducing the lower depth limit of coral growth on reef slopes. Surveys since 1986 indicated that live coral cover decreased by up to 20% on some reefs, although other reefs registered no impact. The reduction in sunlight penetration reduced the lower depth limit of coral growth. In the 1970s, coral growth extended to 10m down the reef slope. Today, growth is restricted to 6m although some coral species still occur at the 8m depth.
Accidental oil spills remain as an ever-present threat. However the 1997 Evoikos oil spill (27,000 tonnes) did not seriously affect coral reefs, although oil contaminated the upper parts of some reef flats.
Other activities that also have an impact on the reefs include recreational and tourist-related use. Negligent or inexperienced divers without proper buoyancy control, leave a trail of broken corals. Anchor damage is caused by fishing boats and pleasure craft. At Pulau Hantu, a popular dive spot, courtesy mooring buoys were previously installed to prevent anchor damage.

A tremedous amount of information on coral reefs in Singapore can be found here.