Dec 3, 2007

Labrador's living intertidal shore

At high tide, when murky waters conceal the intertidal zone, most people might dismiss our shores as being dead. But just because we can't see anything, doesn't mean that there is nothing interesting on the shore.

An intertidal zone is the area of shore that is exposed (and covered) as the tide changes. At low tide, the water often becomes crystal clear and the wonderful range of marine life can be easily seen by ordinary people without having to swim or dive.

Here are some of the sights that we used to see on Labrador during low tides before it got impacted by coastal development and other works there.

A natural and complete intertidal zone is made up of several different kinds of ecosystems. The coral reefs found in deeper waters are part of the continuum of these ecosystems.
The Labrador Nature Reserve shore ecosytems include the coastal forest on the natural cliffs, the natural rocky shores, sandy shores, seagrass meadows, coral rubble and corals on the reef flats which are exposed at spring low tides. The subtidal reefs are part of these as well. These ecosystems are now rare and those on Labrador are the last on the mainland.

The different ecosystems interact and affect one another. Some marine life rely on the different ecosystems to survive. For example, some fishes shelter in seagrass meadows while they are small and move out to the reefs and deeper waters as they mature. Some prawns that we eat do the same.
Labrador's large meadow of Sickle seagrass (Thalassia hemprichii) are the last on the mainland, and probably the largest that are accessible to the general public. This is a photo of the seagrasses taken in Jan 05. Labrador also has patches of other kinds of seagrasses throughout the intertidal zone. There used to be a lush meadow of Spoon seagrasses (Halophila ovalis) where the cofferdam now is.

Sometimes, we would see large carpet anemones among the seagrasses. As elsewhere on our shores, these are homes to tiny anemoneshrimps.
Among the seagrasses were all kinds of fishes
Including the Milk-spotted pufferfish (Chelonodon patoca) and filefishes (Family Monacanthidae) The well camouflaged Feathery filefish (Chaetodermis penicilligerus) takes a keen eye to spot.
Mating Coastal horseshoe crabs (Tachypleus gigas) were sometimes seen on the shore. They are on the list of threatened animals of Singapore due to habitat loss.
Among the seagrasses, one might spot the pretty Moon crab, or the elusive but very common Hairy crab.

The coral rubble area may appear dead, but it's full of life! The dead corals provide a surface for animals such as sponges to grow. And fascinating creatures that feast on sponges may be found there.These include nudibranchs such as the stylishly margined pale yellow Glossodoris atromarginata and the brightly spotted green Ceratosoma sp. nudibranch.
These are two nudibranchs seen whose identity we're still not quite sure of.

Crabs, shrimps and other animals were also commonly seen among the coral rubble.The bright red Mosaic crab (Lophozozymus pictor) is highly poisonous to eat. It is also on the list of threatened animals of Singapore. Many kinds of swimming crabs were also encountered, but this one with the blue rings on its legs is seldom seen elsewhere.

The coral rubble is a great place to spot octopuses.
While divers often seldom encounter these animals, on the intertidal, we regularly see several of different sizes on a single trip. They are more active at night.

While there are a wide variety of snails on our shores, surely the most stunning must be the Spider conch (Lambis lambis).There were regularly seen on Labrador's intertidal shore.

Labrador intertidal got hard corals meh?
Yes, it does! And many different kinds too. There used to be a particularly large clump of branching corals that can be seen at low spring tide.
And other kinds of branching corals were also seen, such as Pocillopora sp.Branching hard corals shelter all kinds of animals, including seahorses!
There were also many large boulder corals, some half a metre or more in diameter.
The above are probably Favid hard corals.

Some unknown boulder corals in bright colours.

There were also several large Psammocora sp. hard corals.

There were also many colonies of disk- and plate-shaped hard corals.
Some plate corals covered large areas of a metre or more.

Encrusting corals like this Goniopora sp. is particularly common even among the coral rubble.
While Anemone hard corals (Goniopora sp.) are often mistaken for anemones rather than hard corals.Among the living hard corals on the intertidal are other animals such as soft corals and sea anemones such as the branched tentacle sea anemone (Phymanthus sp.) and small shy star-like anemones.Colourful reef fishes were also encountered on the intertidal.Such as these two kinds of butterflyfishes: the Kite butterflyfish (Parachaetodon ocellaris) and the Copperbanded butterflyfish (Chelmon rostratus).

A careful observer might spot the Spot-tail frogfish (Lophiocharon trisignatus)! It is actually quite regularly sighted by the wildfilms team as they are very experienced in documenting the shores.

The volunteer team that visits Labrador have been documenting all our shores for the last six years, in still and video. While we are there, we also monitor impacts to the shores such as collection, abandoned driftnets, fishtraps and other abandoned equipment, and impacts of coastal developments.

Among the issues raised in the past include
Poaching of hard corals on Labrador
Large amounts of driftnets abandoned at Berlayar Creek
Collection of rare animals on Changi
and impact of reclamation at Sentosa for the Integrated Resort
which includes comments on the EIA

The team also supports visiting scientists who come to study our shores including
trips with Dr Daphne Fautin (world authority on sea anemones)
trips with Dr Dan Rittschoff and his students from the US

The team also participates in studies of the shores such as
Kok Sheng's study of the recovery at Chek Jawa following the mass deaths earlier this year and Sijie's study of the dog-faced watersnake.

The team also works with efforts such as the relocation of corals at Labrador prior to work on the cofferdam.

Most of the team members are also very active volunteer guides on many of the walks offered to the public (Chek Jawa, Semakau) as well as with groups such the Naked Hermit Crabs and TeamSeagrass.


mantabuster said...

This fatty Ria got nothing better to do? Suck!

mantabuster said...

Nothing better to do!

Hai~Ren said...

And of course, some trolls have nothing better to do.

Even jellyfish don't seem so spineless compared to these wholly useless elements of the Web ecosystem.


Monkey said...

in a survey, it was actually reported that the coral diversity at labrador was even better than at sentosa.

hopefully this is still true after the seacils and expansion of the port. :(

Myk Rosolada said...

Wow this is helpful. I'm studying macroonvertebrate in a intertidal zone here in the Philippines. This blog post is quite interesting. Good job!

Myk Rosolada said...

This is quite interesting. I'm currently studying macro inverts in a intertidal zone here in the Phils. This is quite helpful. Good job!