10 October 2010

Explosion at Chek Jawa, of sea anemones

What are the bazillions of tiny fluffy brown balls strewn all over the seagrasses at Chek Jawa?
I think it's an explosion of baby Swimming anemones (Boloceroides mcmurrichi)!

Here's a closer look at one. It was a mop of tiny tentacles with a very very short foot with which it attaches to the seagrass blade. One of the TeamSeagrass volunteers, Vanitha, even had a video clip of one 'swimming' by undulating its tentacles.
Here's a whole row of them along seagrass blade.
Here's a full grown Swimming anemone, next to the tiny ones (lower right corner).
The tiny balls of tentacles were found everywhere, even among seaweeds.
Wow, it's the first time I've seen anything like this!

I was out at Chek Jawa with TeamSeagrass. After our seagrass monitoring, we had a quick look around. Sadly, I noticed that a tiny patch of Sickle seagrass (Thalassia hemprichii) seems to be bleaching, with yellowish leaf blades. But the rest of the seagrass species seem to be alright. See the TeamSeagrass blog for more about the situation with the seagrasses.
I also saw a few bleaching Haddon's carpet anemones (Stichodactyla haddoni).
But most of the Carpet anemones seemed to be alright. Many in their normal colours of dull green-blue-grey. With a few in bright green or bright purple, as is usual.
Zeehan was also at Chek Jawa, with a team from the NUS Eco Lab to do a survey of the fishes found here. It's very hard work using a huge and heavy fish net.
And then carefully measuring, photographing and recording all the different fishes and their lengths.
Near them, I found the Button snails (Umbonium vestiarum)! It's good to see large patches of these snails, which we call the Jewels of Chek Jawa as they are so pretty.
On the sandy shores, I didn't see as many Cake sand dollars (Arachnoides placenta) as before. And I only saw one Acorn worm (Class Enteropneusta).

Chek Jawa's seagrass meadows seem alright. With the usual sightings of the Warty pink sea cucumber (Cercodemas anceps), and Thorny sea cucumber (Colochirus quadrangularis). The others in the team also saw many Garlic bread sea cucumbers (Holothuria scabra) and some Ball sea cucumbers (Phyllophorus sp.).
I also saw a Noble volute (Cymbiola nobilis), and a Lined moon snail (Natica lineata). As well as many living Gong-gong (Strombus canarium).
There were many Common peacock anemones (Order Ceriantharia) in many different colours. And I saw one Dusky peacock anemone which has more elegant, faintly striped tentacles.
And I saw one living Coastal horseshoe crab (Tachypleus gigas) in the seagrass meadows.
I also saw many crabs on the shore. Flower crabs (Portunus pelagicus) large and small. And one Swimming crab with purple legs (Charybdis sp.) near the rubbly areas. There were also many Striped hermit crabs (Clibanarius sp.).
There were also many tiny little bubble snails (Family Haminoeidae).

I also took the opportunity to do a quick check of the coral rubble area at Chek Jawa. This used to be the best part of Chek Jawa when I first started working on this shore ten years ago. The seagrasses there are nice and green. But as usual, the incoming tide brings in its load of floating rubbish. Sigh.
The only abundant sponge was the Purple branching sponge (Callyspongia sp.). I saw one large sea fan (Order Gorgonacea) and a few very small ones. There were also some patches of Posy sea anemones. And a few cushion shaped clusters of Button zoanthids (Zoanthus sp.).
The area had many fan worms (Family Sabellidae), both the brown banded ones and orange ones.
I saw one large Cake sea star (Anthenea aspera), many large Biscuit sea stars (Goniodiscaster scaber), one Crown sea star (Asterina coronata) and much earlier in the seagrass meadows, one Thorny pink sea urchin (Priodocidaris sp.). Alas, none of us saw the Common sea star (Archaster typicus) that used to be so plentiful at Chek Jawa in the past.
The rest of the team also saw a Purple-spotted yellow flatworm (Pseudoceros laingensis), Little ruby flatworm (Phrikoceros baibaye) and Black prickly nudibranch (Ategema intecta).

On the way back, I had a quick look at the legs of the boardwalk. They are still well covered in pretty encrusting organisms. But the Pink flowery soft corals (Family Nephtheidae) there didn't look very healthy.
The marine life at Chek Jawa have been hit, first by the mass deaths in 2007 possibly due to high rainfall. Then by the oil spill in May 2010. It's no wonder that some parts of Chek Jawa have yet to recover to their past glory...like this photo of the coral rubble area taken in 2002.
Rich coral rubble of Chek Jawa
Hopefully, over time, it will once again return. Meanwhile, it's important to keep checking up on Chek Jawa.

More about Chek Jawa, how to get there, what to see and do and walks you can join.

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