Friday, May 27, 2011

Dugong feeding trails at Southern Semakau

Last Saturday, I joined the Project Semakau team as they surveyed the southern half of the Semakau shore.

As Ron and I were conducting our survey of the biodiversity within our zone, we came across several long "botak" patches of seagrasses. We were thrilled because these really look like dugong feeding trails!

Here is another view the southern most shore with what look like the remains of the feeding of dugongs. It is exciting to know that the dugongs are probably also living among our southern waters.

This stretch of the shore at Semakau is rather unique in its habitat and substrate. There are portions that are a little reefy that are characteristic to southern shores of Singapore.

But there are also quite a far bit of Southern Semakau that looks like a northern shore. With seagrasses and silt-like substrate at some portions, one can find quite a diverse range of creatures here that can be different from the rest of Semakau shore.

One of which would be the numerous Haddon's carpet anemones (Stichodactyla haddoni) that come in various colours.

However, there are many many more of the Giant carpet anemones (Stichodactyla gigantea) here on both sand and also on rocks. Just within this photo, you can already find three of them!

I was flipping rock at a rocky stretch and came across this red crab with a white streak on its carapace. I do not know what is the identity of this crab though.

There were many different types of nerites and I was not proficient in identifying them. Good to have Ron there as he is very familiar with most species. This photo shows the Wave nerite (Nerita undata).

While checking the other rocky parts, I was happy to find the rare Cryptic sea star (Cryptasterina sp.) that I have only seen before at Semakau.

This is how the underside of the Cryptic star looks like. The upper side looks a little cryptic especially when they are hiding among the rocks but the underside reveals their arms and tube feet.

There are MANY of these Common sea stars (Archaster typicus) here. As I was really eagerly looking for the Galloping sea star with Ron, we checked out many smaller star marks on the ground. To our dismay, all belonged to the Common sea stars. No galloping stars in the end after all. :(

A consolation for not being able to find the galloping star was my find of this special sand dollar in green! From far, I thought it was a small carpet anemone in green. But when I went closer to check out, I was surprised to see a green sand dollar! In fact, this is the Laganum sand dollar (Laganum depressum)!

The weirdest part is that I have never encountered a Laganum sand dollar in green. Could the green colour indicate that this sand dollar is diseased or just simply coated with algae?

The underside was not really green. It looked more like a normal Laganum sand dollar.

Yay for this find because it is the first record of the Laganum sand dollar on the intertidal shores of Semakau! :)

Not too sure if I have seen this before, this is the first time I am sure of the identity of this sea hare. This is the Black-tailed sea hare (Aplysia dactylomela) which is a very pretty sea hare that is rather big and has nice patterns on the insides of their flaps. I came across two of them during the trip.

Another special find would be this Margined conch (Strombus marginatus sowerbyorum). It has a somewhat wavy lip on the shell. It is probably my first time seeing it at Semakau.

Who says you cannot find fire in the water? In this stream of flowing water, there is a fire... to be exact there is a Fire's anemone (Actinodendron sp.). Can you spot it?

Here is the closer look at the Fire anemone. It is called a fire anemone because of its nasty stings.

Just next to this above fire anemone, I also found another one in a tide pool instead. Thus, I could take a nicer photo this time.

I was surprised to find a huge nudibranch! It looked like the Spotted foot nudibranch (Discodoris lilacina). But Ron later told me that the identity of this slug should be Sebadoris fragilis.

The edge of the shore at some parts are rather rocky and there were a number of the huge Long-spined black sea urchin (Diadema setosum). They do look rather scary!

Among the rock crevices, I came across one juvenile Circular mushroom coral.

There was also a slug! This is the Black-margined nudibranch (Glossodoris atromarginata).

Strangely, there was this ring of buoy-structure placed on the shore. We do not know what is this for.

After we completed our survey, we walked through the mangroves back to the main road instead of going back to the forest trail. It is my first time walking through here and the ground is very sandy and stable!

Ron pointed out to me some of the rare Api api jambu (Avicennia marina). In fact, this is quite a large tree!

There were several fruits and there was even one that is showing vivipary! As we were in a rush, I did not manage to take photos of the flowers of this rare mangrove tree.

Unfortunately, I came across some driftnets along the way. The most extensive would be this particular driftnet that stretches across the roots of the mangroves.

Here is a closer look at the driftnet. Ria has also seen many driftnets at the northern Semakau shore on the same day. Sigh. Read more about the impacts of driftnets on our shores here.

More photos of the trip here:

1 comment:

James K said...

Sebadoris fragilis and Discodoris fragilis

Discodoris fragilis and Discodoris lilacina

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