The Blue Tempeh
Thursday, April 07, 2005
  WORK IN PROGRESS: Studying Coral Recruitment
If you've recently dived at Pulau Hantu, you might have noticed (or swam into) some new structures that have popped up recently. They might look a bit like THIS:

This is actually a preliminary unit set up at Pulau Hantu. The real ones look like these too...

What are these? Is it rubbish some people have just thrown onto the reef? What is it for?

I'm sure these are just SOME of the questions that pop into your mind when you see these odd man-made structures underwater.

Well, for starters, these are what I call RECRUIT RACKS. They were placed there for research purposes by the Marine Biology Lab for studying coral settlement and recruitment.

What is coral settlement and recruitment?
Well, in essence, it's when small baby corals (coral larvae/planulae) floating about in the water column decide to SETTLE down on something (e.g. rock, dead coral, my terracotta tiles...hehe). These newly settled baby corals are sort of new RECRUITS to the reef and helps to build up the reef itself - just like when a new recruit joins the army...etc. I think you get my point, right? Heh...

Then, what sort of coral recruitment study are we doing?
There are a couple of things we want to find out. Firstly, we want to find out what is the angle of inclination of an artificial substrate that coral recruits like best - whether it is a horizontal, inclined (30 or 60 degrees) or vertical surface. This is the reason why you would probably see a cluster of 4 RACKS set up with these 4 angles.

Secondly, we want to find out at the different coral recruitment rates at different REEF ZONE - reef flat, reef crest or reef slope. This is why you would see my RACKS distributed at these 3 reef zones. You'd probably see it any zone with CORALS in them. You gotta dive deeper down if you want to escape my racks! Heh...

Thirdly, we want to find out the angle of inclination of a surface is most suitable for each reef zone, or whether there is any difference at all.

These are the main things we want to find out...

WHY do we want to find these things out?
This is a very important question. WHY. WHY indeed...WHY WHY WHY...No, it's not the fact that I like to hammer things in underwater and spend weeks setting them up, bolting them in, whether in strong currents and surge, or in slack water...

My buddies helping me hammer in the angle irons. They have to be stable so that they won't get dislodged in currents or surge...

It is because, once we find these things out, we might be able to mitigate some of the horror that has been done to our reefs. Notice that all of my RECRUIT RACKS are set up at RUBBLE AREAS.

Rubble, as the name suggests is defined as loose pieces of dead coral. Our reefs are characterised by the high percentage of RUBBLE cover we have on our reefs. And previous studies have shown that these RUBBLE areas take VERY VERY VERY VERY VERY long to recover and get covered by corals. A scientist have even dubbed rubble areas as RUBBLE KILLING FIELDS. 'Cos the reason why these rubble areas take so long to recover is because when baby corals settle on the rubble pieces, they more often than not, DIE.

WHY DIE? Because the rubble pieces are LOOSE, not fixed. The tumble and turn, causing abrasion of the baby corals. When the rubble pieces turn, they can smother the baby corals too. They can get covered with silt very easily as well (as you would probably have experience with if you dive in Singapore). And they can roll off the reef into the deep abyss (or the not-so-deep abyss, but deep anough) where they can't get enough light, and DIE.

Debby from the HANTU BLOGGERS helping me out by BOLTING IN my TERRACOTTA TILES for the baby corals to settle on...

More DEBBY! hehehe... see her blog on my angle irons racks

Sad cycle of death. Corals in Singapore are getting stressed by all sorts of factors. Siltation/sedimentation, boat groundings, improper anchoring practices, and illegal collection among others. And if the rate of degradation of the coral reef is not balanced by the rate of recruitment and recovery, the reef will eventually die off. And I'm SURE none of us want this, right?

And to find out how to BEST mitigate these affects, and help give our reefs a PUSH (maybe even a SHOVE), we need to know WHAT corals like, how they behave (in a way) and essentially BACKGROUND KNOWLEDGE so as not to do the wrong thing and waste more time. With enough information, we can hopefully specially cater to the rehabilitation of Singapore's reefs. Each reef is unique and so is Singapore's.

One of my two favourite buddy pairs helping me deploy my damn f***ing heavy angle irons.

Ferrying the angle irons to the site....

It's no easy task. It took me and my buddies WEEKS of consequtive diving to set them all up...GAH!

Hopefully, this study, along with others in this REEF RESTORATION AND REHABILITATION project, can provide background information not only about Singapore's reefs, but also reefs similar in nature in other parts of the world. Local data for global use.

The reasons why I chose Hantu West as one of the two locations for my research (the other is Raffles Lighthouse reef), is because, 1) coral spawning has been documented there before, meaning there is a SOURCE of baby corals, 2) Survey results show a drastic almost 50% decrease in live coral cover at this particular stretch of fringing reef (see report on REEF FRIENDS HANTU SURVEY). This site is also dive often by many divers and hold BOUNTIFUL MARINE LIFE! (as you can see from the HANTU BLOG and we would like to find out whether it's recovering and how we can help it recover faster too.

The hero of the day! Caleb, who jumped into the water during lunch time to retrieve a stray plastic bag that had been blown into the water....

Well, you can... LEAVE IT BE, for one. I would greatly appreciate if you do not touch it. WHY? Because it is, after all, an experiment and by touching it (especially the tiles), you are introducing bias. And you could be removing small microscopic BABY CORALS from the tiles!!!!!


It's a DAMN PAIN to set them up and don't get me started about that. My nails are TOTALLY gone, there's scars on both my hands and diving everyday doing WORK when the VIS IS SO BLOODY FANTASTIC is SOOOOOOO ARGGHHHH!!!!!!!!!!! Not that it's bad. I mean beats doing work in 20cm VIS. But but but... ARGHHH it's so TEMPTING to just swim off especially when you see huge schools of yellowtail barracudas, frogfish, nudibranchs and all things SO SO COOL aplenty around you. And they ALL seem to show up when I'm doing work and have no time to photograph anything!


Also, if you happen to be diving and see any of my racks upturns, upset, destroyed, uprooted, cracked, broken, disturbed, PLEASE DO NOT HESITATE TO EMAIL ME!

I also have sediment traps and temperature loggers deployed there so please do not disturb them either yah!

All these racks would hopefully be removed after 4 months unless they are of further experimental of rehabilitation use for the reef. Until then, please please... do not disturb them.

I hope I've answered MOST of the questions that you had in mind... and I hope you understand my explanations. I would have written more if not for the fact that this thing is getting too LONG and you might not even GET this far into the blog....hehehe...

I'll leave you with this photo of an ICON STAR that I came across when doing work at Hantu... This sea star is so ICONIC (geddit geddit) to Hantu... PRETTY AIN'T IT! =)


OH OH OH OH OH ONE MORE THING! If you happen to have FREE TIME and WANT TO BUDDY ME for my work dives, EMAIL ME TOO.
Hi, I was surfing the internet and happened on your blog. I'm quite impressed , with how this all works. This is one to watch.

Best wishes,

B.S. in Electrical Engineering LPN Online Degree
hi.. am julie from phils.. am also a marine biologist, and interested to work on coral recruitment for my study.. am searching and browsing the net to gather more ideas on how things should be properly done.. hope u wont mind me asking some suggestions or recommendations please?? am looking forward.. thank you very much!! my email pls: pls tnx! Godbless..
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