Tuesday, November 17, 2009

Semakau Surveys - Retraining on 15 Nov 09

For the second consecutive day, I was back at Pulau Semakau, this time round for the (re)training of seagrass and line intersect transect. It was really reassuring to know that we have not been doing the wrong things for the past 1 year! I quickly told Hazel the good news today, because we were worried that the seagrass data trends Ron presented last Friday, was partially because our skills improved only towards the last few seagrass transects! Hee hee..

I've never blogged about the Creeper Snails (Cerithium spp.) before, in fact I rarely introduce them to visitors. These poor forgotten snails are the living vacuum cleaners of our shores, sweeping the mud for detritus as food. They are abundant along sandy and slightly muddy shores because they never run out of food! How lucky!

The seeds from the mangrove plant germinates while its on the tree, unlike the seeds of other plants. It forms a propagule and drops in the water once it matures and is ready to lead an independent life away from its parent. Initially, the elongated propagule floats horizontally but over time, it floats vertically after the roots gains weight from the absorbtion of water. Eventually, it takes root after locating a comfortable and suitable environment, just like the propagule in this photo.

We were separated into 2 big groups, and I was to start with the Seagrass team first. Before the training commences, the 'older' volunteers embarked on the mission to find all 6 species of seagrass. Heres five of them, namely, 1) Enhalus acoroides , 2) Cymodocea serrulata, 3)Thalassia hemprichii, 4) Halodule uninervis and 5)Syringodium isoetifolium, laid neatly on the ground.

The 6th species is too small to be seen from the photo, heres a closeup shot of Halophila Ovalis - the Spoon Seagrass, which I have never recorded in all my past transects....heh heh.. hopefully its because it doesnt grow at our transect area!

The training first started with the challenging task of identifying the different species of seagrass. Patiently, we went through species by species to recognise how each of them looks like. The key differences between the species were also highlighted.

Here is a group comparing the actual sea grass vs the photo on the ID chart. Honestly, I must say this is really effective training. 1 year ago, we didnt have the luxury of a trial hands-on training. Identification of the sea grasses gave us much grief initially because we could not visualise how each species look like and thus had much difficulty looking out for them in subsequent transects.

Next was a step-by-step guide on how to conduct the transect - laying the measuring tape from left (shore on our left) to right, placing the quadrat at the right mark, identifying the species and its % cover , epiphyte cover, canopy height, algae species and % cover, fruits & flowers.

The group then dispersed into smaller teams of two/ three for an on-the-job training.

As we wade through the lagoon, we noticed that the water is speckled with many tiny white male flowers of the tape seagrass. A really good sign! The 'older' volunteers were also fed the seeds of the tape seagrass which taste almost like chestnut - thankfully I'm still sitting here, typing away... =)

After an hour, it was time to switch to the 2nd part of training - Line Intersect Transect. As we walked towards LK, we tread past the Sandsifting Sea Star / Common Sea Star (Archaster typicus) lagoon. Heres a four-armed seastar! One of the volunteers thought this seastar had lost an arm - although seastars are more commonly seen with 5 arms, there are those with 4 arms or > 5 arms as well.

Marks left behind by the Common Sea Stars - 凡走过必留下衡迹 applies not only to human beings!

After a round of explanation by LK on how to differentiate the LIT codes, the IDs and how to fill up the form, we spread out to start our trial LIT transect. I forgot to take any photos of LK's training because I was listening intently - I've never done a single LIT transect in the past year! Which is also why, ironically, I find the seagrass transect so much easier.

Zoanthids that were in our path during the LIT. Zoanthids are colonial anemones and have small polyps linked to each other. During high tide, their tentacles are extended to catch preys. I remember during one of the hunting seeking survey which Hazel and I were assigned to survey corals and sponges, we thought Zoantids were corals, and Ascidians were algae! *slaps forehead*

In one of the tidal pools, we saw 2 Sunflower Mushroom Coral (Heliofungia sp.). Often mistaken as a Sea Anemore or a soft coral, the Sunflower Mushroom Coral is actually a hard coral which you can tell from its hard skeleton in the middle. Unlike other hard corals, the Sunflower Mushroom Coral is a single living animal that is free-moving. They come in brown or green colours due to the presence of zooxanthallae. While it does not look like a mushroom now, it comes with a stalk and is stuck to a substrate when it is younger, looking just like a mushroom!

After 2 LIT trial transects, we had about 30mins to do a miniature hunting seeking survey. Our group must be quite lucky to see a few Worm-Eels (Muraenichthys sp.) as they are usually active at night. In addition, I had more than enough time to snap many shots of it. Typically, sightings of it are usually brief as they disappear rather quickly into some holes. Without scales and pectoral fins, they really look like a worm or sea snake with its long tubular body and the way it swims.

A regular sighting at Semakau, this trip was no exception. The Hairy Crab (Pilumnis vespertilio) was still very well-camouflaged and took my teammates some time to spot it.

My first sighting of a Hammer Oyster (Malleus sp), and I went on to see 2 more after LK pointed this one out to me. Unfortunately, the photo I took was not clear enough to depict the essence of its name (no prizes on how it got its name). The two-part shell is thick and T-shaped, looking just like a hammer.

We also saw a few Black-lipped conches (Strombus urceus). Similar to its Spider Conch cousin, the Black-lipped conch also has a strong mascular operculum that helps it pole vault around. I learnt that this conch is on our red list of threatened animal - probably due to the lost of habitat and over collection of its shells.

As I was taking the photo of the Black-lipped conch, Weihan called out to me and shouted 'Stonefish' - gave me a shock! The words 'Sea Cucumber' came 5 seconds later after he realised what he had said. Yup, this is a Stonefish Sea Cucumber (Actinopyga lecanora), looking just like a loaf of bread to me, although many will compare it to a smooth stone - how it looks like when it bloats up into a rounded, smooth shape, apparently when disturbed.

Look at its tube feet sparsely spread out on its body!

We also saw a really big Flatworm (Acanthozoon sp.) about 10cm long! This is the animal that I blanked out when I guided the day before..keke.. Flatworms are really flat and thin and can move into any small crevices. Oxygen diffuses through its body, thus it does not have a respiratory or circulation system. Many flatworms are carnivores and prey on tiny animals by injecting digestive juices into the prey. It then sucked up the liquefied meal.

Marine flatworms are hermaphrodites, that is, each flatworm has both the male and female reproductive organs. Just like human beings, they must find carrying a baby extremely tiring and laborious. Thus some species of flatworm tries to impregnate the other and results in 'penis-fencing' when the two flatworms meet. Amazingly, some species can impregnant each other simply by insert their penis in any part of the body!

Soon, tide was rising and water was becoming murky. We quickly walked towards the shore and along the way, I peeped into the rock where I saw the 2 octopuses the day before. Guess what, one of them was still there (looks like the same one to me)! I bet it had moved during the 24 hrs but being the smartest invertebrate, it recognised its track back to the same hiding place. Its other partner was nowhere to be seen though.

My last sight before leaving the intertidal area was this Fan worm. The head of this segmented worm has feather-like arms, and look just like a mini feather duster. These arms filters the water for plankton or detritus. They live in a flexible tube that is made of sand, their own saliva and mucus (reusing its existing materials, how very environmental-friendly!) which they hide into ,the minute they sense danger. The tubes also keep them moist and safe on occasions when they are exposed at low tide

Although it was a revision of the survey techniques, there were still many new things learnt. Also glad that I had a few first sightings (thankfully don't have to pay the person who pointed out these animals to me, unlike the first sighting of birds, else I'll be totally broke very soon).

Monday, November 16, 2009

Project Semakau - 1st Anniversary celebration

I led my maiden guided walk exactly 1 year ago on 14 Nov 08 on the launch of Project Semakau. Although memories of guiding that VVIP group were still fresh in my mind (yes, we still lament about it once in a while), one year has so quickly passed us by! 1 year later, we are back on Pulau Semakau, still guiding a VVIP group - this time round were friends and family of the GVs.

I met Aida for lunch and both of us were praying really hard for good weather as dark clouds loomed the sky. Once again, Mother Nature was kind to us, and in fact blessed us with very good tide level , enabling us in sharing the amazing biodiversity of the island!

As we stepped out of the Secondary forest, the mangrove trees , as usual, were waiting for us faithfully.  Because of its unique habitat (soft ground, low oxygen content, and high level of salinity), mangrove plants like the Bakau adapt to the environment by spreading its breathing roots out for better balance and grip. I read about the joint project ,in the Sunday times, between Singapore and Dutch to replant our mangroves, which is vital because they are a protective shield for coastal areas against waves. Studies have shown more homes might have been saved in the SEA 2004 Tsunami if not for the destruction of mangroves to make way for urban development. The mangrove ecosystem is also a nursery for many species of marine fish, shellfish and shrimps.

The male Orange Fiddler crabs (Uca vocans) were displaying their brightly-coloured pincer. Male fiddler crabs are identified by their single huge pincer that can be as huge as its body. This large pincer is mainly used to attract females and intimidate love rivals, similar to man who shows off and attract the opposite's attention with big flashy car etc. The bigger pincer really is 中看不中用 which is why the crab feeds on detritus by using is smaller spoon shaped pincer to scope sand to their mouth.

The Hunter-Seekers also found us a Soldier Crab (Dotilla myctiroides). Instead of flattened bodies, their bodies are round and they can walk forward unlike other crabs. The soldier crabs typically move in large groups. Like sand bubbler crabs, the soldier crab eats detritus by scraping sand to its mouth using its pincers . The sand is then discarded, resulting in small, round balls of sand.

Some of my guests squirmed when I told them that this small Sandfish Sea Cucumber (Holothuria scabra) is the edible delicacy we have on the table (though needs to be processed as it is mildly poisonous). Sea cucumbers are animals belonging to the family of sea stars. Most have tiny tube feet which are used to cling to surfaces. It feeds on detritus as it moves in the sand. Unlike human beings where blood is circulated through our body, water is circulated through the sea cucumbers’ body. Therefore, if we really have to, we shouldn’t take them out of the water for too long and not too far from the water surface.

Another familiar face is the Gong Gong (Strombus)  whose population has dropped drastically over the years due to man's collection of them for food. They are scavengers that feed on decaying plant and animal matter (one good reason to think twice about eating them). To move around, they dig their strong knife-like operculum to push off the ground, just like pole vaulting.

We also witness how 2 animals lived in harmony - the Magnificient Giant Carpet Anemone (Heteractis magnifica Stichodactyla gigantea*) and the Sponge.

The sea anemone is home to the clownfish and is covered with short, sticky tentacles, these traps anything edible. They have stingers in their tentacles and simply entangle animals that blunder into them. These stingers inject a toxin that affects smaller animals.

The sponge, on the other hand, is a simple animal as it is made up of only a few types of cells. These cells do not form organs, so a sponge does not have a mouth, digestive system or circulatory system. Sponges filter feeds by pumping water in and out of itself. Because of the channels it has, it is a really good absorbent of water. Yup, this is the sponge that was used at home in the past. Those that we used now, fortunately, are synthetic sponges.

Like many ladies, the Wandering Cowrie (Cypraea errones) is one that is really good at maintaining its beauty. It covers its beautiful shell by a layer of fleshy mantle which works just like facial mask - it repairs and enlarges the shell, protects it from algae and abrasion to keep it smooth and glossy.

In the past, these shells of this beauty queen were used as currency for purchasing. More recently, they are collected for ornaments resulting in over collection.

As we walk along the edge of Sea grass meadow, we saw this Black Sea cucumber (Holothuria leucospilata) - first time sighted in Semakau  though not seen in Semakau for the first time, its the first time we have a photo record*. Still a bonus on the 1st anniversary of Project Semakau... =)

Our first star of the day was the Sandsifting sea star aka Common Sea star (Archaster typicus). This sea star camouflages really well with the sand and feeds on organic detritus found in the sand/ mud. It moves around using its tube feet, which can also gather and handle food to the mouth located right in the middle on its underside.

I was pleasantly surprised to see the iconic Knobbly Seastar (Protorester nodosus) so early into the walk as we usually meet only after crossing the seagrass meadow. Named after the knobs on its body, it can grow up to 30cm wide! Clearly an example of not judging a book by its cover, this pretty Sea star is a ferocious predator to snails and clams. It holds them with its arms and tears them apart. Although stiff looking, it is actually a champion gymnast with flexible arms! This is one of endangered species due to over collection – sadly I’ve seen one in a shop in Plaza Singapore, looking really undernourished.

A Striped Hermit Crab (Clibanarius infraspinatus) was lying beside the Knobbly Sea star and stole a moment of fame from the Knobbly - because its my first time sighting it in Semakau! Hermit Crabs have 4 pairs of leg, but only the first 2 are true walking legs; the last 2 pairs supports the shell. They have a soft, long abdomen thus requires an empty shell for protection. As a hermit crab grows bigger, it has to find a bigger shell – just like us who upgrades to a landed/ condo from a HDB flat. I'm jealous of the hermit crab though, because it can test out the new shell first (while holding on to the old one) before switching. We can't do that, can we?

This is also one of the reasons why we should not take any shells home with us as every empty shell is a potential hermit crab home.

Chee Yee's group saw a cuttlefish and kindly showed it to us. I'm not sure of the ID though.
Cuttlefish possesses an internal structure called the cuttlebone which provides the cuttlefish with buoyancy. A smart invertebrate, it has chromatophores which are cells that allows it to change colour in a flash. They do this to communicate/ warn its fellow cuttlefishes or to camouflage from predators.

Just before crossing the seagrass lagoon, we were greeted by 2 Decorator or Velcro Crab (Camposcia retusa Micippa philyra*). While some crabs traps sediments using small hooked hairs, the Velcro crab plants algae, ascidians, sponges or anything possible on its body to camouflage into the surroundings. Without it moving, I can't tell where its legs/ eyes are at all!

We saw not 1, but 2 huge Noble Volutes (Cymbiola* nobilis) laying eggs (the white jelly-like balls in 1-2-1 patterns) ! Indeed a good indicator that the ecosystem is healthy and is suitable for reproduction. Often collected for its beautiful shell and sometimes for food, they have become rarer on our shores. Another good actor, the volute are ferocious predators of bivalves such as clams. I can't imagine having a pillow pressed against my head - thats how the volutes kills. They use their huge mascular foot to suffocate its prey, and sends its mouth into the shell the moment the prey opens its shell to breathe.

Our 3rd sea cucumber of the day was this Dragonfish Sea Cucumber (Stichopus sp.). Apart from the usual features of other Sea Cucumber, the Dragondish Sea Cucumber can melt and disintegrate when exposed in the sun for too long* It can also shed its skin when stressed, wile it can regenerate his species itself, it is a super long process, and a very painful one too, I would imagine. Thus, we should always leave the marine animals alone in their natural habitat.

This cute Polka-dot/ Funeral Nudibranch (Jorunna funebris) won a few hearts too! Nudibranchs are actually sea slugs and are slow moving dwellers. Named after its flower-like naked gills (meaning of its name in latin) exposed at the back of the body, these slugs are born with shells but lose them when they become adults. Thus, to protect themselves, some developed toxic or bad tasting glands on the skin and warns predators with their bright colours.

Meet our Olympic pole vault champion! The Spider conch (Lambis lambis) got its name from its long spider-like spines on its outer lip. It is very well camouflaged as the outer surface of the shell is covered with a thick layer of algae. Of course, the underside is the complete opposite and its beautiful shell is one of the reasons for its over collection. They don't mean to stare - the adorable large eyes at the end of its long tentacles was really just meant to enhance its vision. Like other conch snails, the animal to 'pole vault’ along the surface with its hooked like operculum, and we were to lucky to see this athlete in action!

Another first sighting - a Headshield slug (Philinopsis pilsbryi)!

Hairy Crabs (Pilumnus vespertilio) were also spotted by very keen eyes! This hairy crab is not the 大闸蟹 people eat. In fact it is mildly poisonous because of its diet that may contain toxic zoanthids. It
is called the hairy crab because it’s body and limbs are covered with long, silky hairs. These hairs trap sediments which allows the crab to blend perfectly with its surroundings. In the water, its hairs 'fluff up', and breaks up its body outline to avoid predator's attention.

Here's a picture of my group wading through the seagrass meadow - all looking quite happy! =)

On our way back, our group was casually looking at the crevices of a rock and was really pleased to find 2 Octopuses. Not sure why they are so near to the shore - Ron said they could be mating! This smartest invertebrate is another super gymnast and can fit into crevices of any shape. They are known to have the ability to learn and were seen opening jars. They can even recognise their tracks - makes me feel inferior because I lose my way and direction sometimes! Another deadly predator, it injects digestive juices to soften the prey’s tissues before slurping it up. Octopuses also have chromatophores which allows it to change colour almost instantly. It can even change its opacity and reflectiveness of its skin.

The intertidal walk was followed by a short coastal clean up. After all the hardwork, everyone was rewarded with beautiful scenario and yummy bbq food at the Southern point. I certainly hope that everyone enjoyed themselves! Looking forward to the 2nd anniversary of Project Semakau, till then, stay tuned!

*edited - Thanks Ron!

Sunday, November 15, 2009

Land Survey 7 - 8 Nov

Finally, after 2 months of Semakau- drought, I was back last weekend for a Terrestrial Survey at the landfill cells. Upon reaching the island, LK gave us a quick briefing, and we split up into the respective groups - the insect team, bird team and forest team.

With no time to lose, the valient bird team trekked through the high grasses and mimosa patches on the landfill cells.

Poles - checked. Mist net - checked. Pegs - checked. Guy strings - checked. With all the equipment ready, we started the first task of setting up the nets. With a team member holding the first pole, another 2 walked , at one's best estimation, 18m away from the first pole and second pole (reminds me of the triple jump days where we have to 量步点 for the runup). The net is then spread out cautiously - the strings are really fine and may get entangled if not handled with care! The poles are then held firmly to the ground using pegs and strings.

Here is an example of a successful set up! 4 more to go to form our 八卦阵!

We initially thought these were Otter footprints! Gim Cheong has confirmed that.. these are cat footprints instead. Hmm.. I wonder what cat it is, could it be the ra-ra cat the others heard previously?

After setting up all the nets, we waiting by the rock bund at a safe distance away from the birds, so as not to scare them away from the nets. We were treated with the usual beautiful sunset @ semakau during the 30 mins of 联络感情time.

We trekked into the landfield cells again and were exhilarted to find 1 bird! The bird is quickly slipped into a bag, to be surveyed back at the NEA office as it was getting dark. We also quickly furled the mist nets, so that bats will not get caught in the middle of the night.

Here's what we have on the first day: a Zitting Cistocola (Cistocola juncidis). Because it was the only star of the day, it had our undivided attention - all of us gathered around LK like paparazzis, totally ignoring the bbq food!

I didnt take any photos at all of our bbq, fireflies and insects encounters [ =(  ], so lets fastforward to day 2. We woke up at 5am in the morning and quickly walked to our nets by 6am. We unfurled the nets as quickly as we can so that we won't miss the 吉时. Again, we waited at the rock bund, watched the sunset and the short skit by July - his attempt to entertain the sleepyheads.

When it was time to check the nets, instead of walking in a single file parallel to the nets, this time round we walked abreast of each other, facing the net, to 'chase' the birds in. This method proved effective, as we found 16 survey subjects in total, and almost ran out of bird bags to keep them.

We settled down once more at the rock bund and the survey commences. Several measurements such as tarsus diameter and its length, length of beak, wings, and the whole body were taken.

The birds were also given a Singapore passport permitting their residence in Singapore. Actually, they were ringed so that their statistics such as travelling patterns can be monitored, after their data is collected in a worldwide database.

Here are the few species we surveyed that morning:

1) The Oriental Reed Warbler (Acrocephalus orientalis)

2) The Black-headed aka Chestnut Munia (Lonchura malacca). This little friend here was so comfortable (after being patted and stroked on its head) that it closed its eyes for a few seconds!

3) Heres a juvenile Black-headed Munia

4) We also have a few Yellow-vented Bulbuls (P.goiavier) who are real whiners. They were whining non-stop when LK was releasing them from the net, causing much anxiety amongst us!

Towards the end of the survey, a few of us took turns to try measuring the subjects. It was really stressful and I was trembling! The Munia was so small as compared to my palm, was so afraid that I exert too much strength. Thankfully, everything went smoothly (albeit with some severely wrong measurements that needed correction by LK) and no birds were hurt in the process!

I'm definitely looking forward to the second survey in early December!