This marked the first leg of the Republic’s inaugural seagrass restoration project, co-led by Dr Samantha Lai, deputy director of the National Parks Board’s (NParks) National Biodiversity Centre’s coastal and marine branch, and Dr Ow Yan Xiang, a senior research fellow at the NUS Tropical Marine Science Institute (TMSI).
The project, which seeks to deepen knowledge of tropical seagrass reproduction and transplantation, was launched in September 2024 with close to $1 million in grants from OCBC Bank.
Seagrass meadows are sources of food and shelter for many marine animals, and serve as nurseries for fish larvae and juvenile fish.
Unlike past projects, this project also has a focus on restoration. In the environment scene, this refers to the act of recovering ecosystems or landscapes that have been damaged.
To researchers like Dr Ow, the launch of the project is timely.
She said: “As scientists, we have always been pushing for seagrass conservation, which I think is very important. But the reality is that seagrass beds are being lost at a high rate – within South-east Asia, for example, the rate of loss is 5 per cent every year.
“And if we’re losing seagrass beds and conservation action cannot catch up, we have to look for a more progressive and less passive intervention, which would be restoration.”
Her team’s work, conducted mainly in the St John’s Island National Marine Laboratory (SJINML), focuses on the sexual reproduction of tropical seagrass.
Unlike seagrasses in temperate waters, which flower seasonally, much less is known about tropical seagrasses, which flower less saliently and regularly.
MORE TO LEARN
Seagrasses are understudied in the region – despite South-east Asia being home to 21 of the world’s 72 seagrass species.
Among the 12 species in Singapore, the reproductive cycles of only two – sickle seagrass (Thalassia hemprichii) and tape seagrass (Enhalus acoroides) – are well characterised.
Dr Ow said: “These two species tend to have longer lifespans and thus bigger biomasses, so their fruits and flowers are more visible.
“But for the 10 other species we have in Singapore, we really have no idea when they flower.”
For Dr Lai and her team, the focus is more on establishing best practices for seagrass transplantation – that is, learning how to plant them so they do not get washed away or die quickly.
To do this, the team has been identifying donor-recipient site pairings across Singapore, where seagrass can be transplanted from a denser, more species-rich meadow – like the one at East Coast – to another that has less or no seagrass, like on the Sisters’ Islands.
Dr Lai said: “When picking out the sites, we look at things like water quality, sediment quality and hydrodynamics.
“We want to make sure that the donor and recipient sites are not too different, so that when we transplant the seagrasses, it’s not too much of a shock for them, and they have a better chance of survival.”
The team regularly monitors the health of newly transplanted meadows by measuring the length of the seagrass leaves and using machines called pulse-amplitude modulated fluorometers to assess how well they are photosynthesising.
While doing fieldwork, Dr Lai and her team are at the mercy of the elements. They also have to work quickly, as the low tides that offer optimum working conditions last only around two hours.
The team has weathered a thunderstorm or two, said Ms Goh May Ching, a research assistant from TMSI.
“We’ve gotten absolutely drenched... I would squeeze my hair and water would come out,” she said.
Dr Lai said survival rates of transplanted seagrass have previously been low, possibly due to factors such as human disturbance or even the movements of crabs, which may uproot newly transplanted seagrass.
The team found that one of the two plots of seagrass plants had close to no leaves left two weeks after transplantation.
Ms Goh said: “It’s a little sad, but the rhizomes (modified plant stems that grow underground or along the soil’s surface) still look healthy, so the seagrass may grow back.”
Besides being food and shelter for marine creatures, seagrass meadows have underground roots and rhizomes that help hold sediment together, reducing coastal erosion.
Additionally, these meadows are excellent carbon sinks – sequestering and storing carbon dioxide that would otherwise escape into the atmosphere.
Dr Ow said: “I think seagrasses punch above their weight. They occupy such a small area of our ocean space – just 0.1 per cent – but they provide so many ecosystem functions.”
MULTIPLE ADVANTAGES
With plans for coastal development on Singapore’s horizon, restoration projects like this may help the Republic expand its land mass while rebuilding marine habitats impacted in the reclamation process.
Dr Lai said: “It’s quite interesting because the site we are on was reclaimed in the 1960s and 1970s, and since then, the seagrass has come back and given rise to a huge meadow.
“This gives us hope that when we do the future Long Island reclamation, we can recreate these habitats to get the species to come back – and, hopefully, restoration will help us to speed up the process.”
Dr Ow and Dr Lai plan to rope in volunteers to help with the restoration of seagrass meadows.
Volunteer teams will be led by members of Team Seagrass, a citizen science programme started by NParks in 2007, where everyday Singaporeans help monitor three of the largest seagrass meadows in Singapore – in Chek Jawa, Pulau Semakau and Cyrene Reef.
The volunteer excursions are popular, Dr Lai said, which the two seagrass researchers find deeply heartening.
Dr Ow said: “Growing up in an urbanised society, most of us really have no opportunity to go out and look at what’s happening at our coastlines.
“But I think it is very encouraging, having the public show more awareness not just of the seagrass, but also the natural coastal ecosystems that we have – that really helps to let policymakers know that this is what people care about.”