25 July 2010

How's the bleaching at Pulau Hantu?

With lots of wet weather recently, we are hoping that there is less bleaching at Pulau Hantu compared to our trip about a month ago.
We started work at 4.30am and stopped as the tide turned to enjoy a spectacular sunrise!

Coral bleaching has been happening throughout the globe for the last few months. Mainly due to higher sea surface temperatures. Just last week, Malaysia shut down major dive sites due to coral bleaching. Has the recent wet weather in Singapore helped to ease the bleaching situation? We head out to Pulau Hantu with much hope.

First the good news: from the portions of the shores that I saw, bleaching is much less. Probably about 20-30% instead of the 60-70% on our last trip. The tide wasn't low enough to get to the reefy parts of Pulau Hantu. But on the higher shores, the corals seemed to be mostly alright.
Many colonies of hard corals were not bleached.
I saw many little coral colonies that were not bleached.
I saw a large colony of Sandpaper coral (Psammocora sp.) that was nice and brown and not bleached.
Among the corals that are still bleaching include many Favid corals (Family Faviidae).
Also still bleaching are anchor corals (Family Euphyllidae) of various kinds, brain corals (Family Mussidae) and Cauliflower corals (Pocillopora sp.).
Many of the leathery soft corals (Family Alcyoniidae) are still bleached.
But I also saw many large leathery soft corals that were no longer bleached. As well as many Asparagus flowery soft corals (Family Nephtheidae) that were more their normal purplish brown colour.
There was one small colony of Acropora coral (Acropora sp.) that was unbleached.
There were some Circular mushroom corals (Family Fungidae) that were not bleached.
But some were bright pink (a sign of ill-health?) with portions that are dead.
Inside the lagoon, under the lush mangrove trees that have settled on the seawalls, were a cluster of several healthy looking Sunflower mushroom corals (Heliofungia actiniformis).
We checked our Burrowing giant clam (Tridacna crocea) and it's still alright too. There are also still lots of Common sea stars (Archaster typicus) on the shores, while the water was teeming with fishes and crabs of all kinds.

Sadly, some of the bleaching corals are starting to die. The top portion of this bleaching Favid coral is starting to get scummed up with algae, an indication that the polyps here have died.
One half of this Cauliflower coral seems to be recovering from bleaching, while the other half is dying (new growth of algae) and long dead (thick growth of scum and algae).
It was alarming to see several large Pore corals (Porites sp.) with a bluish band on the top portion of the colony. This is similar to what I saw on the Pore corals at Sisters Island two weeks ago.
The bluish portion look like recently dead polyps. Here's a closer look at the 'blue disease'.
Is this entire colony becoming sick with the 'blue disease'?
I also noticed that some tangled sponge seem to be rotting and becoming covered with white fluffy stuff that resembles fungus.
Some Smooth sponge seaweed (Cladophoropsis vaucheriaeformis) also had portions covered with white fluffy stuff. Is this some kind of disease too?
There were also several of these floating clumps of rather gross looking stuff. It didn't break apart and comprised some bubbled scum ringed by green hairy stuff. I have no idea what it is.
But all is not lost. All the Magnificent sea anemones (Heteractis magnifica) that I saw were unbleached. As were the Giant carpet anemones (Stichodactyla gigantea) that I saw, and most of these had False clown anemonefishes (Amphiprion ocellaris) in them.
This anemonefish was quite shy and stirred up the sediments making it difficult to take a nice photo of it.
I came across one very well camouflaged octopus. Can you spot it?
I also saw a large scallop (Family Pectinidae) with very long tentacles extended all around the shell!
While there seemed fewer little creatures on the seagrasses, I did see many little coils of tiny orange eggs laid on the seagrass blades.
In an unbleached branching Montipora coral (Montipora sp.) I saw many white tear-drop shaped bubbles. Possibly eggs of some kind of cuttlefish or squid?
The rest of the team also spotted a Longhorn cowfish (Lactoria cornuta) and a Fire anemone (Actinodendron sp.), our first sightings on Pulau Hantu! Chay Hoon saw a stonefish!! As well as all kinds of slugs and other stuff that I always seem to miss.

Throughout our evening trip, the hiss and jet-engine roar of flaring was going on at the petrochemical plants on Pulau Bukom which lies just a few hundred metres off Pulau Hantu. In the dark, it looked like some parody of the musical fountain on Sentosa!
The sunrise reveals the clouds that form over Pulau Bukom from the flaring and other emissions that had been going on all night.
Despite the proximity to these heavy industries, the seagrasses, reefs and other marine habitats of Pulau Hantu remain rich and alive.

Let's hope there is a full recovery from coral bleaching here!

More about coral bleaching on Bleach Watch Singapore

Other posts about this trip
  • Kok Sheng with a 'hell of a lot' of other sightings.
  • Chay Hoon with a close encounter with a stonefish!
  • James with a worm eel.

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