Paying respects to Big Sister

It has become our tradition to survey Big Sister's Island during the Lunar New Year. Part of Singapore's first Marine Park, we did our survey with permission from NParks. After raining all day, the weather eased up just as we started out survey.

We saw sharks, giant clam and other colourful reef life. The rest of the team made all the special finds, I will update later with their sightings. The corals seem to be doing well. The Great billed heron was calmly hunting in the Big Lagoon and did not seem disturbed at all by our presence. On the horizon, the Central Business District on the mainland.

First seen on our last survey in Feb 2022, the large patch (about 10m x 5m) of Branching montipora corals in the middle of the large lagoon seems to be disappearing. The patch already seemed to be more sparse during our Feb 2024, compared to our Jan 2023 survey. Today, there were only small very sparsely scattered colonies. But on a happier note, we had a much better look at corals because both the Sargassum and Bryopsis bloom that dominated the Big lagoon was gone! As well as the cyanobacteria bloom that I saw in Aug 2025.

In the Big Lagoon, I saw the usual variety of hard corals. The medium sized Anemone corals in the middle of the lagoon were doing well. Most of the corals were boulder shaped, but I also saw some plate corals and less common kinds. Including about 10 Mushroom corals from small to medium sized. In Aug 2025, I noticed about 10% of the large Boulder pore corals here had a narrow ring or small patches of dying tissues (white or blue and smells of rotting tissue). I didn't see this today. I didn't see any bleaching corals and most seemed alright.

I saw a good variety of leathery soft corals with some medium-sized healthy colonies. Giant carpet anemones remain abundant - but saw one with a 'Nemo' but it was too shy to be photographed. There were also Frilly anemones, corallimorphs, Asparagus flowery soft corals. I didn't see any that were bleaching.

Many corals continue to grow at the base of the seawall at the Big Lagoon. Many small common boulder shaped and plate forming corals, as well as a few less commonly seen kinds. They seem to be doing well today, clean and fresh most without dead patches. The 'tiles' placed on the seawall is part of work by the Experimental Marine Ecology Lab to enhance biodiversity on our seawalls.

Most of the shores on both Big and Small Sisters' Islands were reclaimed: seawalls were built on the reef edge and the reef flat buried. The original islands were much tinier. Most of Big Sister's Island is ringed by artificial seawalls, which create two swimming lagoons. Since the reclamation, living corals have returned in the big lagoon of Big Sisters Island. Google Earth images already show the newly constructed boardwalk!

The two Sisters Islands were designated as a Marine Park in 2014. Big Sisters Island was closed in 2021 for enhancement works and reopened in 2024 with a new boardwalk and other facilities. Like many parks in Singapore, you can visit Big Sisters Island any day from 7am to 7pm. You don't need a guide or a permit to visit during these times. There is currently a free monthly guided walk at Big Sisters Island of the terrestrial areas, NOT covering the intertidal shore. 

Our survey today was done with permission from NParks. Small Sisters Islands is not open to the public and reserved for research work.

More about the Sisters' Islands Marine Park on the blog and facebook page. More on the NParks website about what you can see and do at our Sisters Islands Marine Park.

Photos by others on this survey

Jianlin Liu



Liz Lim


Others on this survey: Loh Kok Sheng, Lester Tan, Kelvin Yong, Yan Le Su, Mathias Luk, Chay Hoon