29 July 2011

Our sandy shores are alive!

Sandy shores may seem lifeless but they are an important ecosystem!
Living sandy shores of Cyrene off Pulau Bukom
Living sandy shores of Cyrene Reef.
Although mostly hidden from sight, many animals live here and nowhere else! This is why it broke my heart to learn that probably 25 tons of sand on Labrador shore was removed during the Seacil Artificial Reef Project.

One of the typical burrows seen on the high shore are these deep and large holes made by Ghost crabs (Ocypode cerathophthalmus).
Tanah Merah after the oil spill: Ghost crab burrow
Ghost crabs may live on the high shore, but they forage everywhere. Leaving little claw marks on the sand, they sift through the debris left on the high water line, and scuttle around on sandy and other ecosystems on the lower shore.
Horn-eyed ghost crab (Ocypode cerathophthalmus)
Another typical pattern often seen on the sand at low tide are these pretty designs made out of countless tiny sand balls. These are made by the tiny Sand bubbler crab (Scopimera sp.) that sifts through sand grains for edible bits.
Sand bubbler crab (Scopimera sp.)
Here's a closer look at a little Sand bubbler crab making a sand ball as it 'processes' sand on the shore.
Sand bubbler crab (Scopimera sp.)
Another crab typical of sandy shores that create sand balls are the Soldier crabs (Dotilla sp.). When the tide comes in, they seal up the burrow to hide from predators that forage at high tide.
The fiddler crabs (Uca spp.) also make little sand balls and they are much easier to spot. A suitable sandy shore can be home to hundreds of these delightful animals.
Orange fiddler crab (Uca vocans)
It's hot and dry out on the sandy shore at low tide. So many animals are hidden in the sand. If we look, we can see signs of them even at low tide. It's fun figuring out what animals live in the sand!
Sandy shores of Cyrene
Here we can see signs of sea stars, a sand dollar and a buried worm,
as well as lots of bumps made by other tiny buried animals.
Sand stars can be common on some of our sandy shores: The Plain sand star (Astropecten sp.) and the Painted sand star (Astropecten sp.).
Here's some of the different kinds of sand dollars that can be found on our sandy shores. The most commonly seen is the Cake sand dollar (Arachnoides placenta). Less commonly seen is the larger Keyhole sand dollar (Echinodiscus truncatus). And rarely seen is the Laganum sand dollar (Laganum depressum).
Where there are sand dollars, we might find these burrowing Bonnet snails (Family Cassidae) that feed on them!
Often hidden beneath the sand are several different kinds of sea cucumbers. Quite common on the Northern shores are Ball sea cucumbers (Phyllophorus sp.) and Smooth sea cucumbers. Found on many of our shores often near reefs, is the spotted Remarkable sea cucumber (Holothuria notabilis).
Seldom seen above ground are the heart urchins that burrow deep in the sand. Just because we don't see them, doesn't mean they're not there!
The aptly named Bazillion snails (Batillaria zonalis) can appear in vast numbers, leaving trails all over the sandy shore.
Sand tracks: Bazillion snails (Batillaria zonalis)
These sandy things often seen on our sandy shores are sand collars, the egg mass created by mama moon snails!
Oil-slicked Tanah Merah: Sand collars of moon snails
Here's some of the many different kinds of Moon snails (Family Naticidae) that we might see on a sandy shore! Some of these seem to be seen only on sandy shores near reefs.
The delightful Button snails (Umbonium vestiarum) are only found in clean sand. In suitable areas, they can occur in large numbers. These snails come in a bewildering variety of patterns. No two button snails are alike!
Button snails (Umbonium vestiarium)
Also burrowing in clean sand are pretty Olive snails (Family Olividae).
Here's some rare snails that we sometimes see on our clean sandy shores: the elegant turrid snail (Family Turridae), the Clear sundial snail (Architectonica perspectiva), the Fig snail (Ficus variegata) and the Tun snail (Family Tonnidae).
In sandy areas near the mid water mark, we might find the Peachia anemone (Peachia sp.) and some other interesting, yet-to-be identified burrowing anemones.
Our sandy shores are also home to countless worms of all kinds. Some leave obvious coils of 'processed sand' like the Acorn worm (Class Enteropneusta). Others live in tubes.
Acorn worm (Enteropneusta)
Marine life on the sandy shore are food for larger creatures such as shorebirds.
Cake sand dollar (Arachnoides placenta) overturned and pecked
Shorebird prints around an upturned sand dollar
that looks like it has been pecked.
Large visitors to the sandy shores often leave interesting tracks. There were probably made by a Malayan water monitor (Varanus salvator).
Sand tracks: Malayan water monitor (Varanus salvator)?
These are tracks made by otters!
Smooth otter tracks (Lutrogale perspicillata)
The most dangerous animals on the sandy shore are humans!
Sand tracks: Homo sapiens - the most dangerous animal on the planet
Another recent exciting discovery during a Mega Marine Survey were tiny yellow eggs of horseshoe crabs! It appears, horseshoe crabs may only lay eggs in sandy areas in the mangroves. When the little horseshoe crabs hatch, they grow up in the shelter of seagrass meadows. The adults then roam the mangroves and mudflats. This is one example of how marine creatures need a variety of adjacent marine ecosystems to thrive. From sandy shores to mangroves, seagrass meadows to reefs, the different kinds of ecosystems are important for a healthy and rich marine environment.
This is why I was heartbroken to learn during Charles Rowe's recent presentation that the Seacil Project used 'beach sand' i.e., sand from Labrador Beach, to make the concrete for the Seacils (I presume the photo below shows the Seacil team shovelling sand from the beach to create the Seacils). Charles Rowe said about half a ton of sand is used for each Seacil. So for the 50 Seacils eventually placed at Labrador, possibly about 25 tons of sand was removed from Labrador's shore.
All our marine ecosystems are precious! Let's not harm one ecosystem in an attempt to help another.

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