Singapore's Southern Island's: A biodiversity hotspot

Google earth screen shot of the Southern Islands

Just a short boat ride from Singapore's bustling city center lies an archipelago most residents have never explored. The Southern Islands, small, scattered, and often overlooked, harbor one of the region's most surprising ecological treasures. Despite their modest size and proximity to one of the world's busiest ports, these islands support an astonishing diversity of life, from critically endangered sea turtles nesting on sandy shores to rare fungi resembling horse droppings on coastal forest floors. Yet until recently, no comprehensive record existed of what actually lived there. That changed when the National Parks Board (NParks) launched the Southern Islands Biodiversity Survey (SIBS), culminating in what is now one of the most extensive biodiversity databases for small island archipelagos in the region and a blueprint for how to protect what we're only beginning to understand.

Why a biodiversity survey matters (and why it took so long)

Singapore's conservation story has long focused on its mainland nature reserves and iconic spots like the Singapore Botanic Gardens. The Southern Islands, by contrast, remained a scattered footnote some see it as a recreational destinations for beachgoers whilst others historical sites with World War II ruins, and training grounds for the military. Some islands were accessible only by special permission, whilst others saw only occasional research visits. The survey, conducted from January 2020 to March 2022, provided the first comprehensive overview of terrestrial and marine ecosystems across 17 islands and one patch reef. It wasn't just a headcount of species but an effort to document everything from vascular plants and fungi to insects, reptiles, birds, mammals, and marine invertebrates, while also weaving in the islands' geological history and cultural context.

The survey aimed to fill critical data gaps and establish scientific baselines that could inform conservation strategies, track environmental changes over time, and identify priority areas for protection. Information collected during the survey contributed to plans for Singapore's second marine park, designated in the southern part of Lazarus Island and the reef off Kusu Island. Without baseline data, knowing what species are present, where they thrive, and which are at risk, it's nearly impossible to make informed decisions about land use, restoration projects, or how to respond to threats like climate change.

What the survey uncovered: Small islands, big surprises

The results exceeded expectations. The survey compiled over 9,000 records for flora (plants, macroalgae, and fungi) and more than 20,000 fauna records across approximately 6,500 taxa. To put that in perspective, these tiny islands, some barely larger than a football field, support an ecological richness that rivals much larger protected areas.

Highlights:

The islands support 172 native bird species, representing around 40 percent of Singapore's avian biodiversity. That means nearly half of Singapore's bird diversity can be found on these small offshore islands, making them critical stopover sites for migratory species and vital breeding grounds for residents like the great-billed heron and ruddy kingfisher.
The survey recorded 18 critically endangered and 38 endangered animal species, including the hawksbill turtle, Neptune's cup sponge (a massive, rare marine sponge), and the banded swallowtail butterfly. Some species, like the money cowrie, a critically endangered mollusk, were discovered in locations where they weren't previously known to exist.
A locally critically endangered climber plant was spotted for the first time on Lazarus Island during the survey in 2020, alongside unusual finds like the horse dung fungus on Lazarus Island and Pulau Tekukor. These discoveries highlight how much remains unknown about Singapore's offshore ecosystems, even in a highly urbanized and well-studied country.
The survey also documented the diversity of habitats packed into these small spaces: coral reefs, seagrass meadows, mangroves, rocky shores, sandy beaches, and coastal forests. Each habitat supports its own suite of specialized species, from knobbly sea stars in the intertidal zone to Gimlett's reed snake in the undergrowth.

Picture of a ruddy kingfisher (Above), Picture of neptune's cup sponge (Below)

Where biodiversity thrives (and why these islands are vulnerable)

The Southern Islands' ecological richness is a product of their varied habitats and relative isolation from mainland disturbances. Coral reefs and seagrass beds provide nursery grounds for fish and invertebrates, while mangroves buffer shorelines and filter pollutants. Coastal forests offer shelter and food for birds, reptiles, and insects. The islands' geological diversity, spanning different rock formations and soil types, also creates microhabitats that support rare and specialized species.

But this richness is fragile. The islands face multiple pressures: coastal development, recreational use, marine traffic, pollution, and climate change. Rising sea levels threaten low-lying shores, while warming waters stress coral reefs and seagrass meadows. Invasive species can outcompete native plants and animals, and disturbances from human activity, whether intentional or accidental, can disrupt breeding sites and degrade habitats. The survey's baseline data will be critical for detecting these changes early and responding before damage becomes irreversible.

Dr Samantha Lai checking for flowering seagrass at an outdoor aquarium on St John's Island.

What scientists and authorities are doing (and why it's an ongoing effort)

The survey findings have been published online in 16 chapters, with the remaining three chapters covering terrestrial plants, other insects, and the conclusion set to be released by the end of 2025. The entire e-publication is freely accessible on NParks' website, allowing researchers, students, educators, and the public to explore the data.

Beyond documentation, the survey is already shaping conservation action. NParks has established the Singapore Species Specialist Group (SgSSG) under the International Union for Conservation of Nature, bringing together over 100 experts from academia, nature groups, and government agencies. This group will regularly review the conservation status of local species, ensuring that new discoveries or threats are quickly incorporated into the national Red List and conservation priorities.

Restoration projects are also underway. Singapore's first seagrass restoration project, launched in partnership with OCBC Bank, is using survey data to identify suitable transplant sites and test innovative methods to improve seagrass survival. Seagrass meadows are blue carbon habitats. They sequester carbon up to 40 times more effectively than terrestrial forests and provide critical nursery grounds for marine life. Similar efforts are planned for coral reefs and coastal forests, guided by the survey's findings.

But even with this momentum, challenges remain. The islands are scattered across busy shipping lanes, making regular monitoring difficult. Some areas require military clearance to access. Funding for long-term research and restoration is always competitive. And as with any conservation effort, the hardest part isn't collecting data but translating that data into policy, funding, and sustained action.

Final note: Small islands, outsized importance

The Southern Islands Biodiversity Survey is more than a catalog of species. It's a reminder that biodiversity doesn't always announce itself with grandeur. These islands don't have towering rainforests or megafauna spectacles. They're small, scrubby, and easy to overlook. Yet they punch far above their weight in ecological value, supporting nearly half of Singapore's bird diversity, sheltering critically endangered species, and providing ecosystem services that benefit the entire region.

The survey also demonstrates what's possible when governments, researchers, and communities commit to understanding what they have before it's too late. Too often, conservation is reactive, protecting what's left after damage is done. Here, Singapore has taken the proactive step of documenting its offshore natural heritage comprehensively, creating a foundation for informed, science-based stewardship.

The Southern Islands are not isolated relics of a wilder past. They're living, dynamic ecosystems that continue to surprise us with new discoveries. Whether you're a student, a weekend beachgoer, or a policymaker, you have a role to play in ensuring these islands remain biodiversity hotspots for generations to come. The survey has given us the map. Now it's up to us to protect the territory.

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