Wei Ling spotted large meadows of the rare Beccari's seagrass on Kranji Nature Trail at a recent Mega Marine Survey there. And yesterday, Jerome and I saw more of them.
Why is this seagrass so special?
Beccari's seagrass (Halophila beccarii) is rare globally! The IUCN lists it as Vulnerable worldwide. It says the seagrass is estimated to occupy less than 2,000 km² in our part of the world. This is because it has a patchy and fragmented distribution in the Indo-Pacific. It also has a narrow, restricted depth range. It is mainly found in the intertidal zone, an area where there is a lot of human disturbance. Although it is fast-growing and may recover quickly from disturbance, global population trends indicate this species is declining.
In Singapore, this seagrass has so far been seen only at Sungei Buloh Wetland Reserve proper (near the Mangrove Boardwalk) and at Chek Jawa, Pulau Ubin.
Beccari's seagrass is easily overlooked as it is tiny and resembles scum or algae when out of water.
Api-api putih (Avicennia alba) which are plentiful on this shore.
Jan 09, I did go to Kranji specifically to look for Beccari's seagrass. But I didn't come across such vast meadows at that time. Did the seagrasses grow explosively recently? Due to the rainy weather? We noticed that during the mass death at Chek Jawa in 2007, Beccari's seagrasses there did very well. There's still so much more to learn about our seagrasses!
Perepat (Sonneratia alba). I wonder if the meadows helps young mangrove trees to grow, and visa versa? So much more for me to learn!
A study also found that juvenile horseshoe crabs were found in meadows of Beccari's seagrass. So these meadows may be important for all kinds of babies, plants and animals! Here's more about the horseshoe crabs at Kranji.
The only large areas without seagrasses were those heavily impacted by trash. In this photo below, the seagrasses are found in the red circle, while the trashy area in the foreground had no seagrasses.
Joseph Lai earlier kindly identified a similar plant we saw at Pulau Ubin as Caesalpinia crista. This plant is also listed for Sungei Buloh in the Guide to the Mangroves of Singapore. Here's more about the plant on The Total Vascular Flora of Singapore Online.
Black-mouthed mangrove periwinkle (Littoraria melanostoma), and the handsomely striped Lined nerite (Nerita articulata).
Mangrove drills (Chicoreus capucinus) near what seems to be their egg capsules laid on a dead tree trunk.
Api-api bulu (Avicennia rumphiana) has fallen right over. But it seems to be valiantly struggling to survive, with new roots growing downwards toward the ground, and new shoots sprouting at right angles to the trunk. Erosion is a serious problem at Sungei Buloh, and one that is being seriously tackled in the Sungei Buloh Masterplan.
Nyireh bunga (Xylocarpus granatum). While this is sad, it does give a glimpse of what is usually going on underground. Here, we can see all the little roots growing down from the buttress roots of the tree.
this older post.
More about Kranji Nature Trail on the wildsingapore website and Sungei Buloh Wetland Reserve website, with a downloadable brochure (pdf).