The beautiful mangroves of Sungei Buloh (Source: Cheah Esther)

Mangroves are the fighters of the plant world. As some of the only terrestrial plant species to tolerate saltwater, they have learnt to thrive in high-saline, waterlogged conditions by developing a series of adaptations. On our NUS GE3255 Aquatic Ecosystems field trip to Sungei Buloh Wetland Reserve (SBWR), we learnt about some of the wonderful adaptations, or superpowers, of these heroes. Let me introduce them to you!

Superpower #1: Breathing under (salt)water

Ever walked along the coast and noticed odd-looking roots sticking out of the ground? Those are mangrove roots, the key to their survival in wet, muddy habitats. Singapore experiences mixed semi-diurnal tides – two high and two low tides a day. To cope with the constant waterlogged, anaerobic (low-oxygen) environment, mangroves grow aerial roots (pneumatophores) that are able to take in oxygen from the air. These include pencil roots, cone roots, knee roots, and even prop roots that can grow downwards from the branches.

Fig. 1: Cone roots of the Perepat (Sonneratia alba) at SBWR, Sep 2022. Native to Singapore, IUCN Status: Least Concern (Source: Cheah Esther)

Fig. 2: Knee roots of the Bakau Putih (Bruguiera cylindrica) at SBWR, Sep 2022. Native to Singapore, IUCN Status: Least Concern (Source: Cheah Esther)

Additionally, to thrive in the salty water, mangrove roots are able to perform salt exclusion, a filtration process that can remove up to 90 percent of the salt in the seawater that enters their roots (AMNH, n.d.).

Superpower #2: Superhuman strength and stability

How do superheroes remain steadfast amidst the storms of life? They are resilient – they grit their teeth, adapt and persevere. Similarly, some species of mangrove roots have physiological adaptations to increase their stability in the soft, loose soils along shorelines. They have modified roots, such as stilt/prop roots and buttress roots, that allow them to withstand coastal currents and storm surges.

Fig. 3: Stilt/prop roots of the Bakau minyak (Rhizophora apiculatea) at SBWR, Sep 2022. Native to Singapore, IUCN Status: Least Concern (Source: Cheah Esther)

Fig. 4: Buttress roots of the Nyireh bunga (Xylocarpus granatum) at Pulau Ubin, Jan 2009. Native to Singapore, IUCN Status: Least Concern (Source: wildsingapore.com)

Mangroves Protect Us

Just as superheroes protect us, mangroves protect human communities through a range of ecosystem services. In fact, mangrove ecosystems may be the key to defeating one of the greatest enemies of our time: climate change and the resulting sea level rise.

Firstly, mangroves are superb at carbon sequestration – storing carbon that would otherwise contribute to the greenhouse gases in the atmosphere, worsening global warming. They store this carbon in their roots as biomass to stabilize themselves in the soft soils, both above and below ground. Additionally, because they naturally grow in anaerobic conditions, they have adapted to resist decay, becoming long-term carbon sinks as mangrove peat (Srikanth et al., 2015).

Additionally, with rising sea levels and the increasing severity of tropical storms, mangroves provide coastal protection, acting as shields to dampen the devastating effects on coastal communities. The same stilt/prop and buttress roots that give them stability also make them excellent at protecting us from fierce winds and waves, as well as preventing erosion of the shoreline.

Fig. 5: Other ecosystem services provided by mangroves (Source: Worthington et al., 2020)

Protect our Mangroves

As powerful as mangroves are, they too need to be protected by us. Unfortunately, Singapore has lost 90 percent of our mangrove forest area to land reclamation since the 1950s, largely due to rapid urbanisation (Friess, 2015). SBWR is a great place to learn more about mangroves and the superpowers they have. Let’s work towards restoring these magnificent ecosystems by preserving the native species, restoring canopy cover, and reducing our human impacts on their homes!