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below Straits Times Forum Online 12 Sep 05 Coral reefs need help to restore themselves Letter by Dr Chou Loke Ming ST Forum online 7 Sep 05 Better to leave natural coral reefs untouched Letter from the Nature Society (Singapore) We refer to the article 'Adopt a reef, and save the coral' (ST June 28). We'd like to highlight that an artificial reef is not a substitute for a natural coral reef. It would be more prudent to leave natural coral reef untouched if possible. Artificial reef is often mistaken for a quick-fix solution to restore coral reef in areas where corals had been degraded or totally destroyed. Unlike instant trees, these artificial reef balls made either of concrete or fibreglass have to wait many years for scattered bits of corals to attach and grow on the bare surfaces. There is simply no comparison between a two-decade old artificial reef and a natural coral reef in terms of biodiversity and coral growth. Here in our local waters, coral reefs are found growing normally at depths sloping from three to 10 meters. Deeper than 10 meters, coral cover thin out due to lack of sunlight in our normally less-than-clear water. For proper conservation and to maintain coral reefs in their natural state, we should avoid planting artificial reef balls in areas with existing live corals. Degraded coral reefs must also be allowed to recover naturally. Singapore has already suffered a massive 65 per cent loss of local coral reefs. The remaining reefs are found in the southern islands of the Singapore Straits, either fringing the islands or existing as patch reefs. Patch reefs are often exposed partially during extreme low tides. The primary cause for this extensive loss is due to coastal development, where the coastline and the sea have been reclaimed and modified. This loss is further aggravated by the impact of sedimentation from reclamation, dredging and shipping activities. The most obvious loss of coral reef comes from the complete physical destruction of reef habitats by burying them under tons of sand and dredged material from coastal reclamation. Dredging the seabed destroys sensitive ecosystems to the point where recovery is near impossible. Whole benthic communities at the bottom of the sea are wiped out by repeated dredging. The pelagic species that depend on this habitat will naturally move elsewhere. The result is poor fishing in Singapore waters as often lamented by local anglers. The heavy sedimentation created by dredging and uncontrolled deposits of dredged material also smother reef habitats located further away with silt. This is especially so when dredging vessels discharge dredged material by water jets or simply dumping it into the sea from a bottom hatch without a silt screen in place to confine the spread of sedimentation. Tidal currents can carry the silt runoff from these sites over to adjacent coral reefs. Sedimentation clouds the water and reduces the amount of sunlight that can penetrate it. This in turn stuns the growth of coral, which needs sunlight for photosynthesis. Fine sediment settling on coral reef puts yet more stress on coral organisms, causing them to secrete a film of mucous to 'cleanse' themselves of silt. Energy expended by this would otherwise be used in growth. Unless our sea water condition improves, no amount of artificial reefs would help in bringing back the once thriving coral reef we have in our southern islands. Stephen Lau Pway Kian Leong Kwok Peng Marine Conservation Group Nature Society (Singapore) Straits Times Forum Online 12 Sep 05 Coral reefs need help to restore themselves Letter by Dr Chou Loke Ming I REFER to the letter by Mr Stephen Lau Pway Kian and Mr Leong Kwok Peng of the marine conservation group of the Nature Society of Singapore ('Better to leave natural coral reefs untouched'; ST, Sept 7). I cannot agree more that the best option in managing coral reefs is to reduce impact. The writers rightly point out that our reefs have suffered from habitat loss and degradation. However, I do not agree that degraded reefs should be left to recover naturally, especially in our situation where the rate of degradation has been continuous over the past 18 years with no sign of reversal. This is based on the monitoring of live coral cover at five reefs since 1987 by the department of biological sciences of the National University of Singapore (NUS). Before the monitoring programme, anecdotal evidence showed our reefs were much healthier. Reef restoration is an activity meant to slow down the rate of degradation and give reefs better recovery when impact is reduced. The present understanding is that three main restoration strategies can be considered: Substrate modification (if the natural substrate is impacted and cannot support natural recruitment and growth) Transplantation (where the few surviving coral colonies are unable to propagate fast enough or when species are wiped out) Larval recruitment (when larval supply from other reefs is cut off). A plethora of techniques have been introduced worldwide and various claims have been made, but what is important is that before a reef restoration activity is implemented, investigations must be carried out to determine which strategy is best for a specific reef. In Singapore's case, studies showed substrate modification was necessary. Settled sediment on the reef substrate has made it difficult for coral recruits to survive. An inclined surface projecting above the sedimented substrate supported natural recruitment. The fibreglass modules were designed to provide suitable surface areas for coral recruits to settle and grow. In addition, they are light enough to be carried by divers so they can be deployed in exact locations on the reef that are devoid of coral. A three-year field study (supported by NUS, Singapore Tourism Board and Sentosa Development Corporation) showed that natural recruitment was better on these modules than on the natural substrate. The results indicate that this intervention enhances the reef by facilitating growth and survival of transplants and, more important, by increasing the recruitment success. Hoping impact will be reduced and reefs will recover on their own is too pure an approach. They will be degraded to a point of no return where natural recovery is impossible. Suitable restoration intervention will allow us to help the reefs to help themselves. Dr Chou Loke Ming links Related articles on Wild shores of Singapore |
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