09 May 2009

Stormy on Sisters

We arrived under a full moon sailing in a clear star-studded sky. We tried to ignore the flicker of lights in the darker parts of the sky.
But just as we got started on the shores, a fierce wind picked up. We hurried back to the shelter, assiduously avoiding coconut trees and their tendency to hurl missiles on unprotected heads.
With the howling winds around us, lightning played in the sky. If there's one thing I am truly afraid of on the shore, it's lightning. But fortunately, most bolts were landing on the mainland. We amused ourselves while we waited, by trying to capture a bolt striking the land. I wasn't as fussy as others who were waiting for a bolt to hit the city and preferably the hideous flyer.
We also took a closer look at the land hermit crabs (Coenobita sp.) that were plentiful around our hut. These crabs are on our Red List due to habitat loss so it was nice to spend some time with them.

Soon, the wind died down. And lo, there was a patch of clear sky over us! While the weather remained dark and evil all around. We quickly headed out to have a look at one of our favourite shores.

In my previous trips to Sisters I've always been wowed by the hard corals there as well as other amazing marine life.
Sisters Islands have some of the best reefs that ordinary people can easily visit. At night, many of the hard corals have their polyps extended. There were a lot of boulder-shaped corals especially Favids (Family Faviidae) like the one above, and Pore hard corals (Porites sp.).
I stumbled across the large Anemone hard coral (Goniopora sp.) that is at the centre of the swimming lagoon. It has very long polyps so it is sometimes mistaken for a sea anemone. It didn't look too happy this evening. On my past trips to Sisters, I usually see lots of mushroom corals. It was good to see this happy circular mushroom coral. One of the team also saw a long mushroom coral, probably the Mole mushroom coral (Polyphyllia talpina). But there were not as many as we had seen previously. Instead I saw the skeleton of a dead mushroom coral (photo on the left). So it was nice to discover (when I got home and processed the photo), a tiny mushroom coral next to the big one. Mushroom corals start life attached to a hard surface, but as adults are free-living and not stuck down.

I also saw some branching Montipora hard corals (Montipora sp.) and the others also saw some Acropora hard corals (Acropora sp.) while Kok Sheng has posted about some of those he saw. But I just felt as if there not as many hard corals as in the past. The coral rubble area also seemed to have grown bigger and stretched further up to the low water mark. Did the sand move down the lagoon? So much more to learn about our shores.
In the rubble were many small hard corals starting to grow. That's nice to see.However, some were bleaching. Hard corals bleach when they are stressed, thus losing their symbiotic algae that they depend on to make food from sunlight.Bleaching was also seen on some bigger hard corals. The white portion is the bleached part where the polyps are still alive but lack their symbiotic algae. When polyps die, the hard skeleton is taken over by scummy growths, like on the portion on the right in the above photo.

But even dead corals have their role, as support for other animals such as these corallimorphs that look like flattened sea anemones, with an upturned central mouth. They are found in groups of many individuals.
These pretty baby blue ones are frilled corallimorphs with fringed edges.
Another kind of corallimorph has many short tentacles and the group of them resemble a short pile carpet over the coral rubble.

I went to check up on the False clown anemonefishes (Amphiprion ocellaris) that we saw in a Giant carpet anemone (Stichodactyla gigantea) on our previous trips.It was good to see at least one of them still there!
Along the way, I chanced upon this False scorpionfish (Centrogenys vaigiensis). It actually belongs to the grouper family and is not venomous. Cheh!

Today, the coral rubble was draped with some but not too much Bryopsis seaweed (Bryopsis sp.). Among the seaweeds, I spotted the well camouflaged Strapweed filefish (Pseudomonacanthus macrurus). Filefishes belong to Family Monocanthidae which means 'one thorn'. And indeed, members of this family have a single long stiff dorsal spine on top of the head, usually with downward pointing barbs on the edges. The dorsal spine can be locked upright to wedge in crevices, safe from predators and from being swept away by currents. When not in use, the spine is folded away into a groove on the body.The seaweed was crawling with tiny beachfleas (Order Amphipoda).And the tiny and superbly camouflaged Bryopsis slugs (which are probably Placida dendritica). These slugs are sap-suckers and suck the sap of seaweeds. They then take on the colours of their food! The white one probably hasn't eaten enough yet. There are three others in the photo that are well fed. Can you spot them?At sunrise, the tide turned, and I quickly headed to the other lagoon to check on the high shores there.Really really tiny Spoon seagrasses (Halophila ovalis) were growing in this small but calmer lagoon. They seemed to have created these mounds.In the pools created by these mounds at low tide was this beautiful but well camouflaged Common frill-fin goby (Bathygobius fuscus).There was also one Black-lipped conch (Strombus urceus).

In the sandier areas near by were lots and lots of Oval moon snails (Polinices mammatus) bulldozing in the soft sand.
And also many sand collars, probably laid by them?
The higher shores were studded with odd blobs.In the incoming tide, they reveal themselves to be Peachia anemones (Peachia sp.).

As the tide came all the way in, I had a quick look at the shore plants which I'll blog about later (need to sleep now! Tomorrow another predawn trip).

As I met up with the rest, I found out they had seen a really cute Hollow-cheeked stonefish (Synanceia horrida) and a small Yellow-lipped sea krait (Lauticauda colubrina)! And a special mantis shrimp, and more!

Read more about their special finds on their blogs!

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