wild shores of singapore: Mass coral spawning 2014

Our corals made a spectacle of themselves once again, in their annual orgy of sex. Usually around Easter, for lots of egg-citement under the sea!

"BOOM! What a remarkable thing to witness!"
says Debby Ng of the Hantu Bloggers

Once a year, on the fourth month, about four days after the full moon, our corals seed the seas with new life! Thanks to the dedicated team who have been keeping an eye on this event every year, we get a glimpse of what happened in 2014.

What is coral mass spawning?

Some corals release their eggs and sperm all the same time. Called broadcast spawners, these mass spawning events usually occur once a year, a few nights after full moon. The eggs and sperm drift to the water surface where fertilization occurs.

Photo by Toh Chay Hoon on facebook, of spawning,
s well as other cool critters that only she can spot
at Pulau Satumu, Raffles Lighthouse

After a few days, the embryos will have developed into coral larvae that drift about and eventually settle down to form new corals.

While bazillions of eggs and sperms are released during a mass spawn, most don't make it. Hordes of marine creatures gorge on the spawn, from fishes and crabs to jellyfishes. As the tiny coral larvae develop, they have to survive the countless predators that constantly sieve the water for plankton and edible bits. As well as many other challenges that we are still learning about. Excessive sedimentation, for example, can interfere with fertilisation and other aspects of coral larvae survival and successful settlement.

Why is coral mass spawning in Singapore a big deal?

From Sex in the Tropics 2008 on the blooooooooooo blog

Coral mass spawning in Singapore was first recorded by Dr James Guest in 2002. It was the first record of coral spawning in the tropics. At least 18 different coral species from ten genera and five families (Acroporidae, Faviidae, Merulinidae, Oculinidae and Pectiniidae) have been observed to spawn in our waters! Mass spawning occurs on the third to fifth nights after the full moon between 8 and 10 p.m.

In interviews with the media, Dr James Guest emphasised that corals are part of Singapore's biodiversity and natural heritage. "There are 255 species of corals recorded here, and there may be some corals here that were around before Stamford Raffles arrived."

Our corals can be huge!
Like this one photographed
by Toh Chay Hoon on facebook.

The fact that our corals mass spawn shows that our reefs are functioning well! According to Dr James, the number of coral species in Singapore that mass spawn is "as high as on other Indo-Pacific reefs, like the Great Barrier Reef... " This shows how rich Singapore's natural heritage is. We can find right at our doorstep: "diverse, functional and fascinating coral reefs, that people would normally associate only with countries like Australia."

A beautiful series of dive clips of Singapore's wild reefs
compiled by Debby Ng.

In 2014, Minister Tan Chuan Jin joined one of the final dives to view this natural wonder and pronounced them "Absolutely magical". Thanks to Debby Ng, we get live updates of how the dive with Minister went.

The Minister posted photos on facebook!

As well as these interesting points provided by NParks.

General Observations on Coral Spawning

Synchronous mass spawning (as it is called) was first observed in Singapore in 2002.
Dr James Guest was the PhD student who studied this event, along with researchers from the Reef Ecology Study Team (NUS), headed by Prof Chou Loke Ming.
NParks has been monitoring coral spawning together with volunteers and researchers, since 2005.
Areas where spawning have been observed: Pulau Satumu (Raffles Lighthouse), Kusu Island, Pulau Semakau, Pulau Hantu and Labrador Nature Reserve. Spawning seems to be less intense in the other areas, but this could be due to several factors: different composition of species, less than ideal water conditions, less intense monitoring at other sites, and excessive exposure to ambient light at night.
Mass spawning follows the lunar cycle, and occurs for 8 to even 14 days after the full moon in late March or early April, typically around Easter weekend. The peak intensity is around 3 to 5 (and possibly 6) days after the full moon. However, we have only observed the spawning from the 1st to the 8th night after the full moon in Singapore so we cannot say for sure if our corals spawn continue to spawn beyond the observed period.
Up to 35 species have been documented to participate in the mass spawning event in any one year since we started to monitor the spawning in 2002. This was recorded in 2010.
Not all coral species participate in mass spawning events – other species follow different spawning strategies including several (or even monthly) spawning events throughout the year while others are brooders, where fertilization occurs internally and they “brood” their eggs and release mobile larvae. Mass spawning is just the most noteworthy of such events.

Observations on the 2014 Mass Coral Spawning Event

The spawning was predicted to occur following the April full moon, and following previous spawning observations in Singapore, we predicted that the peak spawning will occur from the 3rd to 5th night after the April 15th full moon. The corals are likely to continue spawning for several more nights, but the spawning is likely to be sporadic and not as intense.
A total of 28 (and possibly 30 or more) hard coral species from 18 (or more) genera spawned over the three nights between 7pm and 10pm, along a 100m stretch of reef along Pulau Satumu, where Raffles Lighthouse is located.
There were some observed variations in spawning intensities between species or group of species.
The spawning intensity was generally high and comparable to the observations in 2004, 2005, 2008 and 2010 for three dominant massive or boulder coral species, where egg-sperm bundles were released from almost the entire colony surfaces.
However, three plate coral species did not show an intense a spawning as previous events, with only part of the colony spawning.
There was one new spawning records in 2014 which was not recorded previously.
We are also aware that NOAA (National Oceanographic and Atmospheric Agency) from the US has indicated a 50% chance of an El Nino event this year. The last one was in 2010, which was followed by a La Nina event can causing worldwide mass coral bleaching which devastated many reefs in the region. The corals in Singapore recovered well from that event, but we are still concerned about the potential of another bleaching event this year and are monitoring the situation closely.