Tuesday, July 5, 2016

Predawn at Chek Jawa coral rubble

I'm back at Chek Jawa, one of the two seashores that started my passion in marine life (the other is Tanjong Rimau, Sentosa). It's like visiting your friend that has been there all along through different seasons. That applies to both the shore and myself. We were able to visit this shore with permission from Nparks.

The team soaked in the magnificent presence of the glows from the sunrise after we ended the trip. Yes, we arrived at Ubin before 3am to do a predawn survey and ended at dawn. 

Here's how it looks like way before sunrise. We surveyed most parts of the coral rubble, near the beacon, on this trip.

The sponges seem to be doing better on this trip as compared to last year. Above shows a collage of the different types of sponges.

The Purple branching sponges (Callyspongia sp.) are definitely making a comeback! So much so that they colonised and grow among seagrasses. Something that we don't often see.

With sponges, there would be also slugs that tend to feed on them. Here's the Black-margined nudibranchs (Doriprismatica atromarginata).

The Purple foot nudibranch (Atagema spongiosa) is usually so well camouflaged that we miss spotting them. However, I managed to find this because the purple foot was pointing upwards.

The Pink ascidians are also doing very well at the jetty pilings of Chek Jawa. And of course the Blue-spotted flatworms (Pseudoceros indicus) were having a great time feeding on them.

It's my first time seeing the Marbled flatworms (Pseudoceros sp.) and they tend to be found on Beige sheet ascidians.

Here's a closer look at the Marbled flatworm. The flatworm is edged with a fine narrow line and has really nice patterns on its surface.

How are the corals doing during this bleaching period? Most, if not all of the Flowery soft corals (Family Nephtheidae) are bleaching.

About 50% of the hard corals were bleaching. Most of the ones we came across are Boulder Pore corals (Porites sp.).

Here's a healthy-looking Boulder pore coral that is all brown and well.

The coral rubble habitat is made of a nice mix of seagrass, rubble and sponges. And there's lots of critters to find.

I managed to find one adult Knobbly sea star (Protoreaster nodosus) and believe there are more elsewhere.

Jonathan found this pretty adult-sized Cake sea star (Anthenea aspera) in brown and yellow. Lovely!

And here's the assortment of sea stars sighted on this trip.

As the Flowery soft corals get bleached, the commensal Tiny colourful brittle stars (Ophiothela danae) become more conspicuous.

More commensals sighted include the Sponge synaptid sea cucumbers found around sponges.

Here's another shot of the synpatid sea cucumbers around the purple branching sponge.

And you would notice there are also more critters living among the sponges such as the porcelain crabs.

I was hoping to find the psychedelic Sea apple sea cucumber (Pseudocolochirus violaceaus) and my wish was answered! :)

Will end off this post with two fishy finds- the first one is the Tripodfish (Family Triacanthidae) which I've not seen for a while.

Another not common-sighted fish would be this Brown spotted moray eel (Gymnothorax reevesii). 

Till next year, Chek Jawa!

Monday, January 11, 2016

Northern Chek Jawa survey

We are back at Chek Jawa for our intertidal survey, with permission from Nparks. We hardly have the energy and time to do the northern part of Chek Jawa as we usually get distracted by the coral rubble in the south.

Thus, it is good that we dedicated a not-so-low tide to properly look at the northern part. It was a bright sunny Sunday, perfect for taking landscape shots. And I'm glad to see the seagrasses expanding its territories.

The Haddon's carpet anemones (Stichodactyla haddoni) seem to have increased in numbers! Slow but recovery since the mass death event in 2007.

These anemones look pretty when submerged underwater, together with the seagrasses.

And they are also many of them found exposed on the sandbar during the low tide.

On the sandy stretches and parts of the sandbar, there still are many of the Cake sand dollars (Arachnoides placenta).

This is how they look like when one brushes off the sand that covers their surface. Chek Jawa is indeed rich as there are many sand dollars on its sand bank. :)

Something new that we observe on this trip would be the "explosion" of Pink warty sea cucumbers (Cercodemas anceps) and Thorny sea cucumbers (Colochirus quadrangularis) on the seagrass.

There seems to be more of the warty than the thorny sea cucumbers. The warty sea cucumbers are more brightly coloured.

The Garlic bread sea cucumbers (Holothuria scabra) are abundantly found on Chek Jawa even on a hot day. Though many of them were semi or fully buried underneath sand. I also found one black version of this sea cucumber.

The tip furthest from the shoreline allows one to observe the beautiful Lesser Crested Terns and Greater Crested Terns. One can also see Tekong at the background.

Here's how they look like when they fly off! These terns need to learn how to take turns before flying.

We are reminded that the seagrass meadows are important as they also support dugongs which exist in our waters!

Many of these "botak" or bare trails in seagrass beds are likely to be dugong feeding trails where these magnificent huge marine creatures would graze on the seagrass when the tide is higher.  

I only came across two of these Biscuit stars (Goniodiscaster scaber). They are usually more abundantly found at the coral rubble.

I have not seen the Common sea star (Archaster typicus) at Chek Jawa for a long while! Likely to be since 2012 but of course it is also due to the fact that I didn't look hard enough. Thus, I was thrilled to come across one!

And here's another one close to where I found the first one. Unfortunately, these common sea stars are no longer common after the 2007 mass mortality event. And it seems like the population is as small all along since the beginning of recovery. At least they are still around!

I noticed on this trip that these Cerianthids (Order Ceriantharia) are more commonly found nearer to the south than the north. I have no idea why.

Some cool-looking critters spotted include this Pygmy squid (Idiosepius sp.). They are usually actively swimming and that makes photographing these squids difficult. 

Another tough creature to photograph would be this Kite butterflyfish (Parachaetodon ocellatus) that seems to like being associated with the Haddon's carpet anemones.

Here's a close to this blog post with a half submerged photo of both the boardwalk and the carpet anemone. If possible, we will likely be back again at a much lower tide to do our annual survey at the coral rubble.

More photos of the survey here: https://www.flickr.com/photos/koksheng/shares/i01E2w

Saturday, July 4, 2015

Annual survey at Chek Jawa's coral rubble

Chek Jawa is a special place in many Singaporean's heart. We almost lost this shore to development more than 10 years ago and are heartened to know that it is still around today for many to enjoy and appreciate. For me, it is my first field site as I did my UROPs project in 2007 studying the mass mortality and recruitment of organisms.

Today, the shores of Chek Jawa are out of bounds to the public to prevent trampling and one needs to follow a guided walk to go down and see the richness of the marine habitat. Thanks to permission from Nparks, a group of us were able to do an annual survey of the coral rubble at Chek Jawa this morning.

How is the coral rubble doing? This was one of the habitats that was hit most during the mass death event in 2007. Today, we see the coral rubble very slowly coming back to life.

One can still find hard corals, soft corals and sponges interspersed around the entire area. However the sponge count seems to have dropped since mid of last year.

Most of the hard corals that we can find would be the Pore hard corals (Porites sp.). All of them are doing well and are not bleaching.

I also came across a colony of Disk coral (Turbinaria sp.) and Boulder sandpaper coral (Psammocora sp.).

A special hard coral sighted would be this Grooved brain coral (Symphyllia sp.), probably Symphyllia recta. Many thanks to Danwei for the id! I believe it's our first sighting of the brain coral in the north!

Another hard coral-related special find would be these two slugs found feeding on the Pore hard coral! And that is the reason why some of our corals are greyish-blue as it is a result of being fed on. 

Here's the underside of the slug, where you can still find some remains of what the slug has been feeding on.

Thanks to Chay Hoon for the id, this aeolid slug is likely Phestilla lugubris. It's our first time seeing it on our intertidal shores. As mentioned on the Sea slug forum, they are probably much more common than realised, it is very cryptically coloured and often hidden in crevices and beneath the coral blocks to avoid heavy fish predation.

Another slug that we saw, which is definitely not cryptic in nature would be this flamboyant Blue dragon nudibranch (Pteraeolidia ianthina). The scientific name of this slug is currently being reviewed.

Despite having less sponges on the coral rubble, something worth celebrating would be many of these Flowery soft corals (Family Nephtheidea) that have grown to occupy a small stretch of the coral rubble. This reminded us of Tuas!

Another consolation would be these Barrel sponges (Xestospongia testudinaria) that seem to be doing well! Though they are common on pristine reefs in the southern reefs, we hardly see them on our northern reefs.

Moving on to sea stars which are my favourite, I was delighted to find about 5 of these majestic Knobbly sea stars (Protoreaster nodosus). The one on the bottom right of the collage was found on seagrass!

What was encouraging would be the presence of this young Knobbly sea star which shows that the population is still growing.

The Biscuit stars (Goniodiscaster scaber) are the most abundant on our survey today! They can be both big and small. And here we have a photobombing Fan-bellied filefish (Monacanthus chinensis).

There was even a six-armed biscuit star that Rene found on the shore!

I later also found a six-armed orange Cake sea star (Anthenea aspera)! Cake sea stars come in different colours and patterns.

At first I thought this was a Scaly sea stars (Nepanthia belcheri) but actually it is a large Crown sea star (Asterina coronata)! In fact it is the largest crown sea star I've ever seen.

Missing from our northern shores for some time would be the Estuarine seahorses (Hippocampus kuda). I am glad to find one on our trip today!

This master of camouflage is known as the Velcro crab (Camposcia retusa). It is named as a Velcro crab as it has the ability of the velcro to attached bits and pieces of stuffs on its body so that it can be well camouflaged with the surrounding, especially when motionless.

This brightly coloured and large hermit crab is known as the Spotted hermit crab (Dardanus sp.). We seldom see them on our northern shores.

Another uncommon critter of the north (though very common in the south) would be this Frilly sea anemones (Phymanthus sp.). I only saw one today.

The Snaky sea anemone (Macrodactyla doreensis) is also uncommon on our northern shores. They are named snakey anemones because of their snake-like tentacles that tend to curl.

Close to the end of our survey, we noticed the imminent weather approaching from the west. Therefore we have to quickly evacuate before we get hit by the storm. Let's hope Chek Jawa will continue to remain and thrive for a long time.

More photos of the trip on my facebook album: