Field Studies with the NUS Marine Lab

Date December 19, 2011


False-clown anemonefish (Amphiprion ocellaris)

While many people on holiday during this season slept in on this stormy and miserably wet morning, a group of biologists and volunteers like myself, trudged down to Pulau Hantu for a little exploration. The order of the day was to do a survey of gobies and sand-divers, and retrieve some data loggers and coral samples. Sounds easy.


Work goes on despite the less than favourable weather.

Well, diving was made a little clumsy when all of us were decked out like Christmas trees with various tools from hammers and fish nets to pneumatic drills, screw drivers and other home-made devices strapped to our bodies on top of our dive gear! I even managed to drag along my camera to take some pictures. I was thinking about you!


Orange sea cucumber

Upon my first descent, while on the prowl for skittish and well camouflaged gobies, I came across this conspicuous Orange sea cucumber. If only the gobies we were looking for were as easy to spot and convenient to study as these sea floor dust-busters!


Saddled prawn-goby (Cryptocentrus leucostictus)

This is one of several tens of gobies I encountered today along the reef slope and reef flat. Gobies are arguably the most species-diverse fish in our oceans and though they are common and almost ever diver and walker along the shore might have encountered one, very little is known about them. Which is why we’re doing these trips to learn more about the gobies we have here in Singapore.


Lined chromodoris nudibranch (Chromodoris lineolata) and Goniopora Coral

Sitting around and waiting for fish to show up (more effective than swimming around to look for them because you’re more likely to frighten them away!) means that you also slow down to spot the little things on the reef, like this Chromodoris lineolata that is the smaller than the size of of a single polyp of Goniopora Coral!


Orange-spotted gymnodoris nudibranch (Gymnodoris rubropapulosa)

Not bothering with camouflage was this Orange-spotted gymnodoris nudibranch that was crawling upon the Sargassum algae. I think it was feeding on the tiny hydroids that form a crust upon the surface of the algae.


While I was off looking at fish, Jani Tanzil, a Research Fellow at Tropical Marine Science Institute, was looking into corals. Like trees, corals add seasonal layers, which appear as bands in their hard calcium-carbonate shells. Corals respond to small changes in temperature, rainfall, and water clarity in a matter of months, making them a uniquely sensitive climate record. From a small core from the coral, scientists can put together a very detailed picture of climate in the Tropics—significant because much of Earth’s weather is controlled by conditions in the Tropics. The bore sample on the top has several holes in it from organisms that had burrowed into the coral.


In 2009 and June this year, Jani placed a stain on this particular colony of porites coral (left) which we see as purple-coloured bands. The bands in the coral’s shell can change in thickness with changes in temperature, water clarity, or nutrient availability, so while each band can record the season’s climate, the interpretation of the record depends on how the three factors are related. Jani shared with me that corals in Singapore have been found to grow between 2-2.5 inches/year on average, which is a relatively fast growth rate compared to other corals in the region. On the right is a space of white further down the bore that marks the 1998 coral bleaching event.


Although there are several tens of species of gobies here in Singapore, we rarely have the chance to take a closer look at them. Their small size and elusive nature leave scientists with many questions. Up close, we really get to appreciate the unique morphology of gobies. This one in particular resembles a mudskipper with its huge eyes on top of its head. By the way, did you know that mudskippers are a kind of goby?! But gobies come in many different shapes and sizes and can be found all over the world; in the tropics and in colder waters.


It was worth getting up early and getting caught in the rain and taking 2 very long and cold dives because I learned so much today! It was my first time holding and examining a freshly-cut coral core sample. I found out that not all corals form bands that are so distinct and comprehensive, branching corals for example have a growth rate that decelerate with increasing age and colony size, which makes studying them a little less straight forward. It was a wonderful opportunity to learn and observe field techniques that local scientists are using to understand more about not only Singapore reefs, but reefs around the world as well! Thanks to Dr. Zeehan Jaafar for inviting me for this field trip!

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