31 August 2011

Oil-slicked Tanah Merah: Mating nudibranchs and more!

A tiny fish eats another tiny fish! Tiny squids eating shrimp. Nudibranchs mating! Corals looking lush. Lots of seagrasses and seaweeds!
More than a year after this shore was hit by a massive oil spill, it seems to be getting livelier on Tanah Merah!

I didn't know this tiny fish had caught a fish until I processed the photo! Here's some more photos of it gulping down its prey. How did the prey fish fit inside this tiny predator?! I'm not sure what kind of fish this is. Perhaps a really tiny baby Batfish (Family Ephippidae)? Kok Sheng saw a bigger Batfish on this shore a few days ago.
I also saw this Pygmy squid (Idiosepius sp.) with a tiny transparent shrimp in its arms. I'm fascinated by the tiny suckers on the tiny squid arms!
Here's a look at the little squid changing colours rapidly. Later on, I saw another Pygmy squid, also with a shrimp in its arms.
Indeed, there were also lots and lots of tiny shrimps everywhere. There were also some well camouflaged Saron shrimps (Family Hippolytidae)!
Another exciting encounter for me was this pair of mating Jorunna funebris nudibranchs! This is only the second time I've seen this.
Nearby, was a third Jorunna funebris, crawling away. Nudibranchs are hermaphrodites, each animal having both male and female organs. When they mate, they exchange sperm and each goes on to lay eggs. Perhaps the third one is done with 'mating'?
I also saw this Discodoris boholiensis nudibranch. A closer look and it seems there is at least one more stuck on the rock opposite it. And possibly another one next to it? A mess of mating! Kok Sheng also saw these nudibranchs mating a few days ago.
The shore remains very fishy. There were many of these tiny fishes hiding in small clusters near debris or swimming in small schools. I have seen this fish before, but not in such numbers. I don't know what they are. There were also many tiny Common mojara (Gerres oyena).
Mystery fish no. 1
Here's more unidentified fishes that I saw today.
Upper row: Mystery fish no. 2
Lower left: Mystery fish no. 3, right: Mystery fish no. 4
I saw two Brown-spotted moray eels (Gymnothorax reevesii)! This fish has very sharp teeth and tubular nostrils.
I saw several different kinds of halfbeaks (Family Hemiramphidae).
I also saw several Painted scorpionfishes (Parascorpaena picta), one Freckled goatfish (Upeneus tragula), some White-spotted rabbitfishes (Siganus canaliculatus), many small Cardinalfishes (Family Apogonidae), many medium sized Bengal sergeants (Abudefduf bengalensis) and lots of gobies (Family Gobiidae).

I only noticed this superbly camouflaged Velcro crab (Camposcia retusa) when it moved!
I accidentally shot a photo of a Hairy crab (Family Pilumnidae). There were also many Swimming crabs (Family Portunidae) of all kinds with a lot of small to medium-sized Flower crabs (Portunus pelagicus). I saw one Stone crab (Myomenippe hardwicki) and many small Spotted moon crabs (Ashtoret lunaris).
On the sandy bottom, there were many Gong-gong snails (Strombus turturella). And I came across several that were laying strings of eggs. In one of the photos I took, I accidentally photographed a tiny snail and a tiny slug on the egg strings!
I feel that the corals today seemed to be doing better than on my trip last month. This leathery soft coral (Family Alcyoniidae) that I visit every month seems to have grown enormously! Nestled on it were several small swimming crabs and many little shrimps.
The single Acropora coral (Acropora sp.) I visit every month seems to be doing better. Last month, much of its tips were dead and covered with scum. Acropora corals do grow quickly (for corals) so perhaps it is recovering?
As usual, the most abundant species of hard corals are Favid corals (Family Faviidae). There were also some Pore corals (Porites sp.). Most seemed unbleached.
I saw three small colonies of Anemone corals (Goniopora sp.).
There were many colonies of Flowery disk coral (Turbinaria sp.) of various sizes from tiny ones about 1cm across to medium sized ones about 10cm across.
The special corals I saw on previous trips were still there and seem to be doing well: the large Bracket mushroom coral still with a fan worm on it, the large encrusting plate montipora coral (Montipora sp.), a nicely growing Brain coral (Family Mussidae) and a small Carnation coral (Pectinia sp.).
I saw this hard coral that seemed to have been chewed up. Hmmm. I have no idea what this means.
Today, I saw many Frilly sea anemones (Phymanthus sp.). They were quite large and seemed healthy. This is the first time I've seen so many in one trip for a long while. But I didn't come across any other kinds of sea anemones.
I saw one small patch of Sea mat zoanthids (Palythoa tuberculosa), and many larger patches of Button zoanthids or colonial anemones (Zoanthus sp.).
I didn't see many sponges aside from a small patch of Melted chocolate sponge (Chondrilla australiensis) and some Blue spatula sponge (Lamellodysidea herbacea). There were however, many Thumbs up sea squirts (Polycarpa sp.), most were covered in scummy growth.
The rocky portion in the middle of the lagoon is now golden with lush growths of Mermaid's fan (Padina sp.) and Knobbly red seaweed (Gracilaria salicornia), the most abundant seaweeds I saw today.
I saw a wide variety of other seaweeds too! Seaweeds are food for many animals, so hopefully this means more life will return to the shore.
I was particularly excited to see that  Spoon seagrass (Halophila ovalis) now cover large parts of the rocky portion and some parts of the sandy lagoon!
The Spoon seagrasses seemed healthy although most were covered in scummy growths. I also came across two small patches of Tape seagrass (Enhalus acoroides).
I didn't see any Common sea stars (Archaster typicus) although I saw three 'star prints' on the sand. There were several small herons and other shorebirds feeding on the shore.

There are still signs of oil on the shore. Scum still formed on some parts of the lagoon when the tide turned.
There are still some parts of the lagoon where crude oil lies just beneath the sand. A shallow scrape releases the typical smell of petroleum, and a rainbow sheen. In many parts of the shore, there remains a brownish scum on the sand surface.
There are piles of styrofoam litter in some corners of this very long shore.
Sadly, also litter also floats here and there. A tiny green fish is sheltering among the flotsam of natural and unnatural debris.
Heaps of plastic litter still line the high shore. Thankfully, this will be soon dealt with in the upcoming International Coastal Cleanup Singapore (ICCS) exercise!
It's heartening to see more signs of life on this still oil-slicked shore. I'll continue to check up on it monthly to see how things are. At least, after ICCS, the shore will be cleared of litter!

More about the oil spill on this blog and on the Oil spill facebook page.

Today is the last morning low spring tide for the year! But field trips continue, with the evening tides!

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