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So what's the fuss about?

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How did we miss Chek Jawa?

Lessons learnt

Articles cited or referred to
by N. Sivasothi
photos by Alan Yeo
 
So what's the fuss about?
In Singapore, each remaining patch of coastal ecosystems is precious. At Chek Jawa, not one, but several share the area - rocky shore, beach, mangrove, mud flats, sand flats, sandbars and sea grass line the coast, and a benthic habitat lies beyond the lagoon. Since each of these habitats are populated in part by a unique community, that amplifies the diversity!

For example, amongst the rocky shores reside the Purple Climber Crab (Metopograpsus quadridentatus), and under rocks are several specis of tunicates and sponges and more crabs - Petrolisthes lamarcki, Leptodius exaratus, Myomenippe hardwicki. The mollusc seen were four species of Thais (Muricidae), at least three species of Morula (Muricidae), Pugilina sp. (Melongenidae), Nerita sp. (Neritidae), Littoraria (Littorinidae), Siphonaria (Pulmonata), Turbo brunneus,and other invertebrates like the Banded bead anemone Epiactis sp., Pomatoleios sp. (Serpulidae), large densities of Ligia exotica (Isopoda), barnacles - Balanus sp. and less commonly, the very large Tetraclita sp.

The sandflats on the foreshore however, are covered with an extensive marine angiosperm (mainly Halophila spinulosa) turf, interspersed with Enteromorpha and Ulva patches. This area also supports various anthozoans: at least two species of sea-pens, tube anemone Cerianthus, carpet anemones Stichodactyla, echinoderms (sand dollars, sea cucumbers, sea stars and brittle stars), bivalves (window-pane shells Placuna) and tubiculous polychaetes.

Sea Cucumber



Sea Horse


Sea Pen

Gastropods found here include Umbonium (Trochidae), Nassarius (Nassariidae) and Vexillum (Vexillidae). The bivalve Mactra (Mactridae) is also common. Dead shells of Pinna also found suggesting live populations in the vicinity.

The estuarine reef-flat of the southern shore is characterized typically and strikingly by a diverse sponge fauna and presence of the horned seastar Protoreaster nodosus. Macroalgae, ascidians and the venerid Gafrarium are also very common (also attested to by locals).

A source for all the coral rubble? T. S Teh, a geographer with the National Institute of Education at the Nanyang Technological University, profiled the beach in mid-2001. He hypothesises that buried beneath the coast and lagoon are remains of a Holocene coral reef!

The certainly rare elements for in Singapore are the sand dollars, carpet anemones, sea grass patches, the Nypa fruticans (Nypa or atap) grove, octopi, the muricid drill Thais rugosa, Cowries and one of only four surviving species, the living fossil Giant Horseshoe Crab (Tachypleus gigas).


There have been suggestions that there are more than 10 species of sponges. The true extent may never be known. J. Hooper and others who reported more than 1,500 species of sponges for the South China Sea region, mention that the greater diversity is represented in shallow waters.

Yet they suggest this may represent a third of the actual available number species. The high level of endemism is surprising - less than 5% are widespread across the Indo-Pacific, i.e. there is a high chance that the sponges in Chek Jawa are likely to be endemic! Interestingly, the bioprospecting potential of sponges is so high such that the US National Cancer Institute (NCI) has large and well-curated collection.

Sponge

Even the shore plants that survive the demanding environment of strong winds, salt spray and a very hot sun include at least 15 rare species including Knema globularia, a previously extinct species, according to Mr Joseph Lai, a botanist.

After just a few days of sampling, the team from the Raffles Museum of Biodiversity Research (at left) are already excited by the possibility of never before recorded species of fish from Singapore amongst the more than 80 species caught - a shad (Nematalosa galatheae) and a pipefish (Hippichthys spicifer). And a large piece of red algae drifting near their nets may also turn out to be another new record!
 
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  Sivasothi, N. 2001. Chek Jawa, lost forever? Asian Geographic, 10: 12-25.
This article appeared in Asian Geographic: Journal of our Environment (Sep-Oct 01 issue)

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