Threats to Singapore Reefs

Threats to Singapore Reefs

There were once over 60 offshore islands and patch reefs around Singapore, most of which were situtated south of mainland Singapore. However, since the 1970s, major land reclamation were carried out on the mainland and offshore Southern islands, adding to Singapore total land area. However, the most significant cause of reef degradation in Singapore is sedimentation. Land reclamation (occured along the Southwest Coast of the mainland and on some of the offshore Southern islands), dredging of shipping channels and dumping of earth spoils have increased the sediment load. Increased sedimentation can affect the reefs by causing a a slow but steady reduction in live coral cover (surveys since 1986 indicated decrease by up to 20% on some reefs), and by reducing the lower depth limit of coral growth on reef slopes (due to reduction in sunlight penetration). In the 1970s, coral growth extended to 10m down the reef slopes but today, growth is restricted to 6-8m.

Accidental oil spills also remains as an ever-present threat. Though the 1997 Evoikos oil spills (27,000 tonnes) did not seriously affect coral reefs, it contaminated the upper part of some reef flats.

Recreational and tourism-related use also have impacts on the reefs. For example, anchor damge cause by fishing boats and pleasure craft and negligent/inexperienced divers with proper bouyancy control, which can severly damage fragile, slow-growing corals.

The 1998 coral bleaching event

Sea temperature around Pulau Hantu and St John's were elevated by 1-2degree celsius from March-June 1998. 50-90% of all reef organisms in Singapore was affected, particularly the hard corals, soft corals and anemones. The bleaching effect extended until 6m, the lower growth depth limit for coral growth locally.