Sunday, April 28, 2013

Sentosa shore is crabby alive

So many swimming crabs swimming around the shallow waters of Sentosa shore. They looked like they are playing catching with us.
Swimming crab
A small team head out early in the morning to check out the shore of Sentosa while another team when out for a recce trip for the upcoming Mega Marine Survey Southern Expedition.

Other than the numerous swimming crab of various sizes, the Spotted moon crabs (Ashtoret lunaris) were also rather active today. Great match for the full moon in the sky. The moon crabs move quickly in the shallow water and they burrow in the sand very quickly. It was difficult to get one that stays still for a long time for you.
Spotted moon crab
Other than the big crabs, there were also big and tiny hermit crabs scavenging on the shore. I only managed to find one Striped hermit crab (Clibanarius infraspinatus).
Striped hermit crab
In this photo, you can see how the hermit crab uses its last pair of legs to hold onto the shell. Amazing animal. Only the head, pincers and walking legs of a hermit crab contains hard shell. A layer of skin covers the body of the hermit crab and this skin is very fragile and easily dries up under direct heat. That is why the shell is very important in protecting the body of hermit crab.

There was a live Giant top shell snail (Trochus niloticus).
Underside of shell
Closeup of the snail
There were many tiny transparent shrimps with long pincers. It was difficult to get a good photo of the shrimp in situ as the full outline of the shrimp is hardly visible in the photos.

What is this eel like animal with yellow spots on its body?
I am not sure as it was swimming and keeps going into hiding. This was the best image of it I got. My guess is either a moray eel or eel-blenny.

In the trip, I save a stranded juvenile Carpet eel-blenny (Congrogadus subducens) which probably skipped onto dry sand while wriggling around in a rather shallow pool. I gave it a push to help it get back into the shallow pool.
Carpet eel-blenny
For a pre-dawn trip, it was easy to spot fish as they are less shy and more still for us to see.
Lined cardinalfish (Cheilodipterus sp.)
False scorpionfish (Centrogenys vaigiensis)
White-spotted rabbitfish (Siganus canaliculatus)
Black eeltail catfish (Plotosus canius)
Oh dear, Ivan and I saw some of the corals bleaching. Most of them are partially bleached. I found one small colony that is fully bleached.

Oh... I spotted a pair of Lined chromodoris nudibranch (Chromodoris lineolata), the only nudibranch we saw in this trip. The nudibranch is rather small and I would have miss this if I had not looked closer. I probably missed many other nudibranchs on the shore.
Chromodoris lineolata
Two of them!
Beautiful feathery gills
Pretty rhinophores
We spent most of the time one half of the shore and we end up with little time to check the other side on  Tanjung Rimau. I did a quick walk through the shore while checking out the floating security barriers. Most of the Tape seagrass (Enhalus acoroides) were long and grew rather well but there a few patched that were quite short but not as short or burnt as those I see at Cyrene.
Tape seagrass cropped short
Patches with longer grass blades
More Tape seagrass
I have blogged about the floating security barriers in a separate post.

Look! Some one lost one side of the scuba fins.
Scuba fin
While heading to washup, Ivan and Marcus spotted an unknown bird while looking at the peafowl and her chick.
Yet to be identified bird
Peafowl and her chick
We were blessed with great weather and a slight rain came when we were about to end out trip.

Read about what interesting animals the other team saw at a dual Terumbus trip in Ria's blog.

Security Barriers at Tanjung Rimau, Sentosa

In a blog post written by Ria Tan dated on 7 January 2013, she noticed the floating security barriers have been put up along the Sentosa shoreline by the Marin Police. Before that Ria mentioned in another post dated 26 June 2012 about the note from Port Marine Notice (dated 20 April 2012) about the construction of floating sea barrier at Sentosa Cove. In the notice, a map drawing shows the barrier possibly ending off at Tanjung Rimau, just off Rasa Sentosa.

Here are the images Ria took on 7 January:
Floating security barrier in front of Sentosa's natural shoresFloating security barrier in front of Sentosa's natural shores

From Ria's images it clearly shows a line of barrier parallel to the shoreline and it ends off with an opening.

While visiting the shore on Saturday's predawn intertidal trip, I took the opportunity to check out these floating security barrier and the possible damages it did to the natural shore. And it looked slightly different.

Here is a video of the security barrier:

And a still image

It seems that there was modification made to the floating security barrier to "closeup" the security along the shoreline of Sentosa.  Joining the line of barriers parallel to the shoreline is a closing line of barrier that cuts through the natural shore, ending at the rocky cliff.
"New" line of barrier that ends at the rocky cliff
Taking a closer look at how the blue drums are connected.
Connected by chains
The end of the barrier line is chained to a t-shaped construction metal bar, already beginning to rust while a loop goes through a rock wedged between a large opening.
Last drum on the line.
Chained up at the rocky cliff
More chains looping through a rock
In the midway of this additional barrier, there was a large concrete cube that looks like an aide to weigh the barriers down.
Concrete cube with chains
How the barriers flow past the concrete cube
On this part of the barrier, the chains were attached with some thick cables.
Thick cable
How has this line of security barrier affect the shore life?
Many of the barriers have been covered by algae, barnacles and possible other tiny marine life on the portions where the barriers will be submerged when the tide comes in. Some of the drums are hanging above the shore while some are sitting on the shore.
Drum with algae and barnacles growing, hanging slightly above the shore
Another drum, sitting on the shore
The actual impact of the floating security barrier is unknown and it requires further monitoring. It is possible that as the tides rises and the strong waves created by passing boats and ferries, the drums will sway and hit the shore in vertical and sideway manner.

A video shows how strong the waves can get and how rough the security barriers are rocking.

This natural shore of is monitored by TeamSeagrass and some of us who monitor our shores regularly. However we are always fighting with time and tide and there is just to many shores for us to cover. 

The next time I visit Tanjung Rimau again, I shall do a better check on the natural shore along the floating barriers.

Ending off, here's the view from the rocky cliff.

Celebrating Earth Day with the Naked Hermit Crabs at Pasir Ris mangrove boardwalk with Buffy fish owl and Hornbill

Last weekend, Singapore's nature community was buzzing with activities to celebrate Earth Day. This year Earth Day falls on the 22nd April 2013, which is a Monday.

The Naked Hermit Crabs did not forget about celebration Earth Day too. We held a free public guided walk at Pasir Ris Park mangrove boardwalk for 15 visitors. We saw many interesting things we usually did not get to spot thanks to other kind park users.

A very special find for both the guides and the visitor was the Buffy fish owl. It was the first time seeing the owl for many of us, including me. Thanks to Ivan's friend, Ho Yong Tze, for showing it to us.
Buffy fish owl
[Photo by Sean Yap]
What a great way to allow the only children visitor enjoy this beautiful bird by sharing my binoculars and position it at the correct angle on the boardwalk to allow her to see too. It was so delighting listening to the child describing the colour and pattern of the owl to me.

At the start of the walk, we had a pair of Plantain squirrels welcoming us to the boardwalk. It looks like they found some food to nibble.
Plantain squirrel
[Photo by Ria]
Wow! How lucky I was. The cicadas were calling out very close to me. If you only use your ears, you will be able to spot them easily. This cicada was seen during my pre-walk checkout trip and it was at eye level, though at an awkward position on the boardwalk. I managed to get a few decent side profile shot of it before I lost it. 
Cicada, side view
During the walk, one of the visitors 'helped' to locate this cicada and it is now resting higher up on the tree but facing us.
Cicada, dorsal view
Sean found a large gathering of Cotton stainer bugs on one of the Sea hibiscus tree. One of the groups of cotton stainer bugs can be seen easily at eye level. The adult bug has a white cross on its back while the nymph looks like a red dot. I did not see any nymphs around.
Gathering of Cotton stainer bug
Adult cotton stainer bug
One of our sharp eyed visitors spotted a few of these large snails feeding on the drier grounds in the mangrove. These are the Belongkeng snails and they are probably grazing on the algae on the ground. In the photo, you can actually see the snail. Many people would usually pass these badly covered shells as empty shells but on a more careful look, the shell might contain a snail.

Some of our visitors were treated to this special visitor, a very small leaf insect on the boardwalk. It probably fell off from a nearby tree. On the return journey, the guided saw it again and Sean took some photos of it.

Opps! It looks like I intruded the privacy of this two crabs. It was the only children in the group who mentioned to me she spotted a crab that took my attention. From the boardwalk, the crab looks unusual and different. My big camera with macro lens caught sight what this unusual crab position looked like.

Oh, a pretty inch worm on the boardwalk.
It reminded me about the inchworm song by Tony Bennet but on youtube, but I only found the version sung by Charles Aznavour the Muppet show.

At the end of the walk, we stopped at a tree be intrigued by this young Malayan water monitor lizard staying in a cavity of the tree truck. This is not my first time seeing such behaviour. We wonder how it gets in and out. The lizard does not seemed disturbed by our presence.

On the pre-walk trip, I was walking through the boardwalk looking for the Atlas moth caterpillar we saw during our March trip. However I could not find the caterpillar. Instead, an Oriental piped-hornbill flew by and stopped on a branch 3m away from me. Wow! I was so happy to be able to see the bird that close. Of course, I was happily snapping away with my big camera.
Where the bird landed in front of me.
It hopped higher
It hopped around for a while and flew off to another tree next to the boardwalk further down.
Ivan mentioned at there is a pair of hornbill residing in Pasir Ris Park. Could this be the one of them hunting for food?

It was a great Earth Day celebration.


Related Posts Plugin for WordPress, Blogger...