Monday, August 11, 2014

Coral health check at Terumbu Raya

I'm back at Terumbu Raya, a submerged reef off northern part of Pulau Semakau after 3 years! My previous trip was in Jul 2011. Terumbu Raya, also named as The Great Reef in Malay is home to thick growths of hard corals and its associates by the reef edge.

How is the coral bleaching situation at Terumbu Raya? We are glad to see that most of the hard corals are fine except for some partial bleached ones like the coral on the top left hand corner of this photo.

The Favid hard coral (Family Faviidae) on the left is partially bleached on the top. We also observed this at Pulau Hantu two days ago. There was also a completely bleached Carnation coral (Pectinia sp.).

On this survey, we also realized that the Brain corals (Family Mussidae) are more affected by bleaching as compared to other types of hard corals. Ria caught the "cold-bug" by saying it isn't good to be too smart. Can you get the joke? Haha!

Fortunately, not all the brain corals are badly affected as some are still alright while others just look more pale than other types of corals.

I only came across a few Circular mushroom corals (Fungia sp.) and these two are partially bleached.

Out of the four I saw today, this is the only Circular mushroom coral that was not bleaching nor dying.

The mushroom corals are not abundant on Terumbu Raya. I only saw this one Tongue mushroom coral (Herpolitha limax) which looks healthy. 

Here is a collage of the various other types of hard corals found on Terumbu Raya. They all are healthy and colourful.

At the reef edge before the reef plunges into the deep end is where corals are most abundant. In this photo are two plate-like corals namely the Disk coral (Turbinaria sp.) and Ridged plate coral (Merulina sp.).

At certain stretches, the corals can be jammed quite close to each other such as this photo of the green Pebble coral (Astreopora sp.), brown Carnation coral (Pectinia sp.) and the blue Favid hard coral (Family Faviidae).

Can you see a black blob on the left of the Euphyllid coral (Family Euphyllidae)? What do you think it is? :)

The black part belongs to the mantle of the uncommon Four-spot cowrie (Cypraea quadrimaculata). It is only my second time seeing it.

Just right below the huge colony of the rare Moon coral (Diploastrea heliopora) is a Bulb-tentacled sea anemone (Entacmaea quadricolor).

Terumbu Raya is home to many of these anemones and here's one with a shy Tomato anemonefish (Amphiprion frenatus).

There were also a couple that showed signs of stress as they were partially bleached. Thankfully, none were fully bleached as what we saw in 2010's coral bleaching.

Despite the abundance of the Bulb-tentacled sea anemones, there are fewer Magnificent anemones (Heteractis magnifica) on this reef. I only saw two today.

The Fire's anemones (Actinodendron sp.) are more common on Terumbu Raya! In fact, Terumbu Raya is one of the few shores where I first learnt about this nasty-stinging anemone.

I am usually not very sharp at finding sea slugs, thus am quite proud to have found 5 different types of nudibranch on my own. This red and white Starry mouthed nudibranch (Bornella stellifer) was also last sighted at Hantu two days ago.

The other slugs that I came across include the Lined chromodoris nudibranch (Chromodoris lineolata), Black-margined nudibranch (Glossodoris atromarginata), Black phyllid nudibranch (Phyllidiella nigra) and Pimply phyllid nudibranch (Phyllidiella pustulosa) (from top left to bottom right).

This is my first time seeing the Dragonfish sea cucumber (Stichopus horrens) on Terumbu Raya though it has been sighted here before.

It's always a joy to find the Cushion stars (Culcita novaeguinea)! These huge and heavy sea stars are usually found on healthy reefs and they are capable of feeding on hard corals.

Resting by the side of the sponge is a huge Fan-bellied filefish (Monacanthus chinensis). It was rather motionless even when I drew nearer to the fish.

A special find for today would be the Tiger cowrie (Cypraea tigris)! Though I have seen it in a few occurrences, this is the first time I spotted it by myself. Hahaha.

This is how the cowrie looks like when the mantle is retracted thus exposing the brightly patterned shell. According to the Singapore Red Data book, although this cowrie was considered one of the commonest cowries of the Indo-Pacific, and present on Singapore reefs in the past, the tiger cowrie is now exceedingly rare.

Jianlin found a huge Fluted giant clam (Tridacna squamosa) by the reed edge! Not sure if this fellow was previously sighted by the others.

And just before we leave, I stumbled upon yet another one close to but not by the edge of the reef. It's fascinating to know that there are more clams that we thought on our reefs.

For today's trip, we landed way before sunrise with the bright moon illuminating the clouds and the shore.

And soon after sunrise is when the tide slowly crept back in. Pei Yan did a drone scan around the vicinity and we will soon be able to have a aerial look at how the surrounding reefs and Pulau Semakau look like from the top.

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