25 June 2011

Rare mangroves at Pulau Semakau, and sea anemones

Brandon and I stumbled across a well grown Api-api jambu (Avicennia marina) at Pulau Semakau today! This is my first time seeing this particular tree, which is located on the main shore!
We are not sure if the tree has been recorded yet, so Brandon kindly takes a GPS reading with his phone. As usual, when I don't bring my GPS we find something interesting. Thanks Brandon!

From the fruits, flowers, trunk and roots of this tree it sure does look like the Critically Endangered Api-api jambu (Avicennia marina).
This tree was vigorously fruiting! Although the fruits were still small.
Earlier on, we checked the smaller Api-api jambu tree nearer the high shore, which is well-known and well-loved. It seems to have grown taller and thicker!
Here's a closer look at the fruits, flowers and trunk and roots of this Api-api jambu.
Another very rare plant on Pulau Semakau is the Critically Endangered Bonduc (Caesalpina bonduc). This is the only known female plant in Singapore so far. And it is fruiting! There are still some green prickly pods. And several brown opened pods. I last checked up on this plant in April.
The Vulnerable Bakau pasir (Rhizophora stylosa) is quite common on Pulau Semakau. I had a closer look at them too.
Many of the Bakau pasir trees were flowering profusely with long dangling propagules from their branches.
The other common mangrove trees on Pulau Semakau are also doing well. Like this explosion of flowers in an Api-api putih (Avicennia alba).
We were actually on Pulau Semakau today to remove an abandoned driftnet. Joining us were Dr Daphne and Nicholas, who are going to look for sea anemones on the high shore. The tide is not very low today.
After we finished with the net, besides looking at mangroves, we also look closely at the high shores for sea anemones. There are some areas where there are lots of zoanthids (Order Zoanthidea), which are not true sea anemones.
In the search for anemones, I came across many many Cryptic sea stars (Cryptasterina sp.) under stones all along the length of the shore! So far, I've only seen this sea star at Pulau Semakau so it's good to know they are quite well distributed along the shore.
We also saw many of these blobs in the mangroves and muddy shores. We saw this during a recent Mega Marine Survey at Sungei Pandan, and Dr Tan Koh Siang shared that they are the egg mass of some kind of slug.
By the time we were done with removing the abandoned driftnet, Dr Daphne and Nicholas were deep in the mangroves!
We all came across many small to tiny sea anemones on the high shores! On big rocks, small rocks, on mangrove pneumatophores. But we didn't find some of the anemones commonly seen on our Northern shores, like we did at Lim Chu Kang recently. What does this say about Semakau mangroves? It requires more study!
The sea anemones look slightly different when they are more relaxed. Dr Daphne has to take a much closer look at them to be sure of their identity.
Dr Daphne stays in Singapore until early July, so there's MORE anemone hunts to look forward to!

More about the net removal today on the Project Driftnet blog.

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