Lee Kong Chian Natural History Museum

Estuary and Mudflat

Photo credit: Wang Luan Keng


Mudflats, also known as tidal flats, are coastal wetlands formed in sheltered shores where greater amounts of sediments (silt, clay, and detritus) can be deposited by the rivers or tides. They are often associated with estuaries, areas where the mouth of a river meets the sea. Estuaries are also places where mangrove habitats can be found, thus mudflats can usually be seen situated adjacent to mangroves.

Due to the deposition of detritus, the substrate in mudflats is rich in organic content but it is low in oxygen due to the water-logged soil. Mudflats are inundated by the tides twice per day. When it is low tide, the exposed area serve as an important feeding ground for many animals, especially for migratory wading birds which to refuel on their long journeys. The soft mud is also home to a range of burrowing animals, typically invertebrates such as worms, crabs, and shrimps. Mudflats also serve as important barriers against soil erosion along coasts.

In Singapore, mudflats can be found particularly along the north coast which is facing the sheltered Johor Straits, such as at the Sungei Buloh Wetland Reserve (SBWR), and Kranji wetlands. It is worth noting that the mudflats in the SBWR, where large numbers of migratory birds congregate annually, is recognised by Wetlands International as an important part of the East Asian-Australasian Shorebird Site Network. On the eastern side of Singapore, Pasir Ris Park and Chek Jawa also has easily accessible mudflats. Mudflats are also found on the relatively undisturbed Southern Islands, such as Pulau Semakau and St John's Island.

Seen as economically useless in the past, mudflats  were often reclaimed and converted to farmlands. Mudflats are under threat globally due to various factors, including rising sea levels, agriculture, coastal developments, pollution, and dredging for shipping and ports.


Estuary, Mudflat

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