Policy

he 350-hectare Semakau Landfill, the first offshore landfill in the T world, received the 2019 Hassib Landfill – J. Sabbagh Award for Engineering Construction Excellence on 23 November A Haven For 2019. It was quite coincidental that Semakau Landfill won the engineering Coastal And award for its outstanding engineering feat twenty years after its completion in 1999. A Marine seven-kilometre rock bund demarcated 350 hectares of the sea linked to two islands Biodiversity that were previously inhabited. The larger is Pulau Semakau endowed with rich coastal and marine habitats including mangroves, The pressure to manage its solid waste and coral reefs and seagrass beds. Reclaimed the lack of land led to ’s decision from the sea, the landfill area is demarcated to develop the world's first offshore landfill. by a perimeter bund within which, cells Development considerations included were progressively emptied off seawater minimising impacts to biodiversity. Today, and filled with incinerated ash. it is not only a landfill, but also a coastal and marine biodiversity haven. With the way forward, it can be featured as an Saving The Mangroves and Coral illustration of sustainable development Reefs on and Around Pulau which addresses many of the United Semakau Nations Sustainable Development Goals. It is lesser-known that during the physical development of Pulau Semakau, measures were taken to minimise environmental Lim Tian Kuay impacts and to safeguard and enhance the 01 Line transect deployed to measure reef condition. National Environment Agency natural ecosystems, like mangroves and coral reefs. Firstly, to make up for the loss L.M. Chou of 13.6 hectares of mangroves that had National University of Singapore to be destroyed during the development, Professor Leo Tan and the late Professor Biodiversity of Pulau Semakau Lee Sing Kong advised on the replanting of At least five different types of ecosystems mangroves at alternative sites. This was a are found at Pulau Semakau, a testimony major undertaking at a time when mangrove of its rich and diverse biodiversity. restoration was not that well understood. The ecosystems represented on both the Secondly, Professor Chou Loke Ming landfill site and the more natural areas are: proposed the use of fine mesh silt screens 1. Grass- and scrubland on the filled cells to prevent sediment generated by the a. Many coastal pioneer plant species like perimeter bund construction from spilling casuarinas now thrive on the island. over to the coral reef and seagrass bed on b. Wildflowers are widespread. the island’s western coast. c. Many bird species, both resident and These measures were implemented migratory species like the Great-billed as part of the Environmental Impact Heron, Grey Heron, Large-tailed Nightjar, Assessment to mitigate adverse effects Barn Swallow, Pacific Swallow, Kingfisher, on Pulau Semakau’s coastal and marine Changeable Hawk Eagle, Malaysian habitats. The coral reef was monitored over Plover, Pacific Golden Plover, etc., have the three years it took for the construction been sighted. of the perimeter bund. Permanent transect d. Many arthropod species like bees, lines and quadrat plots were established and butterflies, beetles, dragonflies, etc. surveyed to assess reef condition [see Figure are present. 1]. The results indicated minimal impact e. Marine life including hard corals, algae, to the reef with live coral cover remaining and fishes have been observed in the intact throughout the development. unfilled cells currently holding seawater.

042 envision issue 17 043 02 An aerial view of replanted mangrove at the 04 Seagrass and macroalgae on reef fat. Policy Northern plot of Semakau Landfll. 05 Intertidal reef fat at west of Semakau with mangroves in 03 Replanted mangrove at the Southern plot of the background. Semakau Landfll. 06 Coral with laminate growth form.

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2) Mangrove forests [Figure 2 and Figure 3] 3) Seagrass meadows [Figure 4] a. Apart from the natural mangroves on the western shore a. Seven seagrass species have been recorded in the waters of from which 13.6 hectares were lost, two other sites of replanted Pulau Semakau. Making seagrass meadows their home is a mangroves north and south of the natural mangroves now diverse assemblage of animals including fish, crabs, sea thrive. Based on a novel plan by Professor Leo Tan and the late cucumbers, sea urchins, sea slugs, etc. Professor Lee Sing Kong, then respectively the Director and Head b. TeamSeagrass, an active group of volunteers who collaborate of Biology at the National Institute of Education, the replanting with NParks and a global research programme, Seagrass-Watch, of mangroves compensated for the loss of mature mangroves as monitors the species and health of the seagrasses periodically. a result of the decision to anchor the perimeter bund to the 4) Inter-tidal zone of mud, sand and rubble [Figure 5] eastern shore of Semakau. The replanted mangroves are now a. This area is rich with Knobby Sea Stars, Common Sea Stars, teeming with biodiversity like the natural mangrove and crabs, flatworms, sea anemones, shrimps, sponges, jellyfish, etc. continue to provide ecosystem services such as shore protection 5) Coral reefs [Figure 6] and coastal erosion prevention. a. Coral reefs are the marine equivalent of terrestrial tropical b. Diverse mangrove trees like Avicennia spp., Rhizophora spp., rainforests. They rival in biodiversity. Coral reefs are vital are present. for human survival as they harbour many species that are c. Snails, crabs, spiders, reptiles and amphibians, found in valued seafood. abundance add to the rich mangrove habitat biodiversity. b. Coral reefs also serve a protective function for the coasts. c. Many species are colourful and much sought after in the marine aquarium trade. Sea fans or gorgonians are spectacular branching species on which tiny gobies, cowries, shrimps and sea anemones, find shelter. 06 044 envision issue 17 045 07 Framework Of The Singapore Index On Cities’ Biodiversity. Policy

Way Forward Such initiatives will address many of the Monitoring of Pulau Semakau’s seawater United Nations Sustainable Development quality showed no indication of Goals. Since there is rich biodiversity on deterioration. This allowed biodiversity and around Pulau Semakau, efforts should to thrive and in turn the rich biodiversity be made to track and develop the existing can help to keep the water clean by locking biodiversity, using relevant indicators and pollutants and sediment. At the same time, as well the underpinning principles from the clean environment can support other existing monitoring tools and science- activities. A floating fish farm has been based approach like the Singapore Index operating just off Semakau’s western reef on Cities’ Biodiversity [Figure 7]. It would and a fish hatchery on the island draws be beneficial and appropriate for relevant seawater not far away from the landing site agencies such as NEA and NParks to of barges transporting incinerated waste. collaborate and lay the groundwork on Singapore’s first coral nursery was launched monitoring and developing the biodiversity by the (NParks) in of Pulau Semakau for the benefit of 2007 at Pulau Semakau. Coral fragments generations to come. are grown in the nursery to a certain size The Semakau landfill is transforming before transplanting back to coral reefs in sea into land using incinerated waste, restoration and enhancement efforts. and it is done with due consideration The way forward is to continue and to biodiversity enhancement and strengthen the collaboration with agencies environmental quality maintenance. We such as NParks on biodiversity conservation soon have to deal with the challenge of as the drive towards a Zero Waste Nation climate change. What is the future of the is also synergistic with biodiversity landfill with rising sea levels? Raising conservation for the following reasons: the bund will increase the capacity of the 1. If there is zero waste, then there will landfill to receive more incinerated waste be lesser need for the expansion of Pulau but can it be done in ways that do not reduce Semakau as a landfill, therefore, there will biodiversity but promote it instead? be more land and sea for Singapore’s native The expertise of academics could be plants and animals. tapped. There is a growing core of 2. If there is zero waste, then there will amateur naturalists, non-governmental be lesser pollutants including plastic that organisations, photographers and citizen will be contaminating the land, freshwater scientists who are interested in biodiversity, bodies, coastline and seas. environmental issues and climate change. 3. If there is zero waste, less energy will Everyone can play a part to maintain be used in treatment, hence, less carbon the health and vibrancy of our natural emissions. environment. 07

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