Hello everyone! Hope you had a great week!
This week we will be taking a closer look at my all-time favourite, the Pasir Ris Mangroves, and how it is a shining example of mangrove restoration to the rest of the country! But first of all, I need to make a clarification. In my previous post I mentioned that the Pasir Ris Mangroves was not natural but regenerated on reclaimed land in 1996. However, upon further research, I have found that this is not entirely accurate and I deeply, sincerely apologise for that. That said, let that take nothing away from the fact that what really happened was a truly unique and unconventional conservation plan which turned out to be hugely successful, as I’ll explain in detail below.
The actual situation is that the 5ha patch on which the boardwalk is currently located (original mangrove plot in the diagram) is in fact a natural, mature mangrove ecosystem which was carefully conserved. However, its adjacent shorelines were reclaimed in 1978 to create recreational spaces in today’s Pasir Ris Park (Lee at al., 1996). The mangrove restoration I mentioned about occurred on these reclaimed areas from 1978 to the mid-1990s, specifically along the banks and river mouths of Sungei Tampines and Sungei Api Api.
As a result of these developments, the 5ha patch is technically no longer a “coastal ecosystem” per se, which under normal circumstances would certainly lead to ecological collapse. But this issue was cleverly addressed by the extension of Sungei Tampines across the reclaimed land, as well as the digging of a rivulet to let tidal water flow in and out of the mangrove plot. How innovative is that! I was truly stoked to see how the authorities managed to marry the 2 opposing ideals of reclamation and conservation to create such a win-win situation.
Source: Ramos & Hesp, 2018
The adjacent Sungei Api-Api river was also diverted from its original course such that it flowed through the reclaimed land and directly into the sea, rather than through the 5ha mature plot into Sungei Tampines (Ramos & Hesp, 2018).
So where does mangrove restoration fit into this picture? After reclamation was completed in 1980, mangrove saplings were replanted along the river banks and river mouths of Sungei Api-Api and Sungei Tampines, on the newly-reclaimed land. Paying close attention to slope gradient, tidal limits, salinity and sediment accretion in their plans (Ramos & Hesp, 2018), the authorities created conditions for the saplings to be inundated around 40 to 50 times a month to allow for their establishment and colonisation(Lee et al., 1996).
And these efforts eventually bore fruit! A study conducted by Lee et al., 1996, showed that by 1991, 11 years after inundation commenced, the mangrove vegetation belt had thickened substantially along the river embankments and even expanded beyond the estuary and along the shoreline. Extensive networks of pneumatophores had also been regenerated on the new plots, and observable fauna such as crustaceans and molluscs were found to have permanently inhabited the plots within just 3.5 years (Lee et al., 1996).
Evidently, these findings point to the surprising feasibility of mangrove restoration in Singapore. The fact that the mangroves were not only able to survive reclamation works but also subsequently colonise new ground successfully shows that with similar effort, we can actually work towards helping our mangroves to flourish again! The key to success lies in the provision of all the right conditions as mentioned above, be they human-engineered or not, as long as they allow for the tides to come in and work their magic on the mangroves.
Today, the restored mangroves paint a picturesque view at the river mouths of Sungei Api-Api and Sungei Tampines. While the trained eye might be able to tell that these mangroves are planted and not mature ecosystems, they nonetheless serve their purpose by both stabilising and beautifying the river embankments, leading to the flourishing of biodiversity there!
References:
Lee, S. K., Tan, W. H., & Havanond, S. (1996). Regeneration and colonisation of mangrove on clay-filled reclaimed land in Singapore. Hydrobiologia, 319(1), 23-35. doi:10.1007/BF00020968
Ramos, S., & Hesp, P. A. (2018) Mangrove establishment in an artificially constructed estuarine channel, sungei api-api, Singapore. In: Vol. 25. Coastal Research Library (pp. 419-427).
Hi Marcus,
Great post.
Could I publicly give you a pc of feedback ?
Instead of “However, upon further research, I have found that this is not entirely accurate and I deeply, sincerely apologise for that.”…
What about “I did some more research and realised this is not entirely accurate, and that motivated me to write this post on how the Pasir Ris mangroves constitute a mangrove restoration success story.” ?
I mean… everyone makes mistakes, correct ? And mistakes are opportunities, no ? Do we have to apologise if no harm is done ?
Hi Dr Coleman,
Thank you so much for your understanding! Yes I do agree that mistakes are ok and should be embraced as learning opportunities, because we learn the most from them. But I do believe that inaccurate information, or any mistake for that matter, warrants an apology, whether or not any harm is done, so I’ll stand by that. I’ll try to be more careful in future. Thank you! 🙂
Hey Marcus!
This was a really interesting read! I agree with you that it is super cool that Singapore has managed to carry out land reclamation works and at the same time undertake restoration efforts for mangroves! I would never have associated land reclamation with conservation prior to reading this blog post, due to land reclamation’s notoriety when it comes to the environment.
Do you think incorporating mangrove restoration into reclamation efforts would mitigate the negative impacts land reclamation has on the environment or is land reclamation something that we should stay clear of?
Cheers,
Divina
Hi Divina,
Thank you so much for your comment! Regarding your question, I think that land reclamation as a whole is definitely something we should stay clear of. The adverse environmental effects of land reclamation go way beyond just the loss of mangrove ecosystems, causing disruptions to coastal hydrology, destruction of other non-mangrove ecosystems, and most significantly the increase in turbidity of the water due to the massive input and stirring up of sea-floor sediment into coastal waters. The increased sediment load in the water decreases sunlight penetration into the depths, severely affecting the photosynthetic processes of phytoplankton and zooxanthellae, resulting in the disruption of the ecological balance.
That being said, for a small rapidly-developing island nation like our country, I am certain that as much as we do not want it to happen, land reclamation will still inevitably take place. In this case, we could say that mangrove restoration wherever possible is the least that we should do to mitigate the ill effects of reclamation. Mangrove restoration is not going to address the root of the issue, it is not going to regulate shoreline erosion in other places nor clear the water of its turbidity. But at the very least, it salvages the precious mangrove ecosystem that reclamation takes away. Hence, the scenario of mangrove restoration with reclamation is definitely not a favourable substitute for no reclamation at all, but given our circumstances, it is the right thing to do. Hope this answers your question Divina, and thank you so much!