24 July 2020

Terumbu Hantu not much bleaching

Dr Jani Tanzil alerted us that mass coral bleaching may have started on our shores since the second week of June. So we are on the look out for this as we check up on Terumbu Hantu. This little submerged reef just off Pulau Hantu has some lovely corals including this nice patch of Acropora corals.
Elegant acropora coral (Acropora sp.)
Today, we didn't see many bleaching corals. I estimate about 5% of the hard corals that I saw were showing stress (paler than usual or with bleaching portions) or with recently dead patches.Most of the leathery soft corals were alright. The situation wasn't as bad as what I saw during mass coral bleaching in 2016.


This is what I saw during mass coral bleaching here in 2016.
Today, the situation is not that bad. Only a handful of hard corals were outright bleaching. Although some had pale or bleaching portions, or recently dead portions.
Living reefs of Terumbu Hantu, Jul 2020
The Sargassum seaweed, however, is starting to bloom, so it was a little difficult to get a good look at the reef edge. There are some nice large colonies there, and most seemed alright.
Living reefs of Terumbu Hantu, Jul 2020
Here's a compilation of some of the hard corals I saw, with a ruler for further study by others.
There was a cluster of small Omelette leathery soft corals which had a few bleaching patches. But most of the colonies were alright.
Omelette leathery soft coral (Sacrophyton sp.)
I have noticed that stressed leathery soft corals tend to 'melt' from the centre. Perhaps a way for them to break up into smaller colonies - so that some part may survive the stress?
Omelette leathery soft coral (Sacrophyton sp.)
There were several other different kinds of leathery soft corals. They were alright.
The Flowery soft coralsGiant carpet anemones, Frilly anemones and corallimorphs I saw today were alright. I saw many zoanthids and only one small patch of Sea mat zoanthids was rather pale.
The rest of the team spotted the Merten's carpet anemone that we have seen before here. It was not bleaching.
Similar to our last survey here in Jul 2019, today I saw many scattered clumps of Tape seagrass and they all had longish leaf blades (about 30cm). During our last survey in Jun 2018, those I saw were mostly cropped short - hopefully this is a sign of a recovery? The rest of the team did a quick check on Terumbu Pempang Kecil nearby and there are still sprinkles of Spoon seagrass there.
Tape seagrass (Enhalus acoroides)
One reason we visit this submerged reef is that it has been damaged by large dive boats in the past. This is a photo of the MV Nautica a large live-aboard dive boat which was seen high and dry on the living reefs of Terumbu Hantu on 9 Nov 2014. We checked for damage to Terumbu Hantu in Jan 2015 and again in Aug 2015.
Photo by Toh Chay Hoon on facebook.
Large holes which are bare of living corals and other reef life are likely to be caused by boat strikes such as the MV Nautica grounding. This larger hole at the edge of the reef flat is starting to be colonised by Acropora and other hard corals.
Boat strike on Terumbu Hantu, Jul 2020
There's another smaller hole.
Boat strike on Terumbu Hantu, Jul 2020
Despite being next to petrochemical plants and surrounded by heavy vessel parking, this little reef flat still has lots of lovely corals. I hope it stays safe until we can visit again.
Leathery soft corals

Fate of Terumbu Hantu?

Terumbu Hantu is one of the existing natural shores that may be impacted by the landuse plan by the Ministry of National Development released in Jan 2013 in response to the Populations White Paper with a 6.9 million population target. The dotted margined blue areas are "Possible Future Reclamation".
The other shores impacted by this plan include Pulau Jong, Pulau Hantu, Terumbu Pempang Darat, Terumbu Pempang Tengah, Terumbu Pempang Laut.
Singapore's submerged reefs are often out of sight under the high tide and thus forgotten. Let's hope Terumbu Hantu stays safe until we can visit again.

The Singapore Blue Plan 2018

Pulau Semakau and nearby islands and submerged reefs have been recommended by the Singapore Blue Plan 2018 for Immediate Conservation Priority. The Blue Plan recommends the intertidal and subtidal marine areas of Pulau Semakau and adjacent Pulau Hantu, and Pulau Jong to be designated Marine Reserve.

The Blue Plan highlights that Pulau Semakau and its associated patch reefs comprise many ecosystems: coral reefs, mangrove areas, intertidal sandflats, seagrass meadows, and coral reefs. The subtidal area of Pulau Jong is larger than the terrestrial area. Pulau Hantu is a popular dive site has seen increasing interest in the past decade due to biodiversity awareness. If protection is accorded to these three islands, zonation plans for use can be implemented to manage tourism and human impacts.

DOWNLOAD the Plan, SUPPORT the Plan! More on the Singapore Blue Plan 2018 site.

Photos by others on this survey

Richard Kuah


Dayna Cheah


Shawne Goh


Jonathan Tan


Surveys by others on other shores

Kok Sheng surveyed Tanah Merah/East Coast shore


Chay Hoon surveyed Changi


Vincent Choo surveyed Changi


Teo Say Chong surveyed Changi Point.


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