10 February 2011

Gifts of the Flood: mangrove seedlings on Changi!

I've been checking Changi for the last four days. Yes, even though the tide was not low.
With every tide, a new load of mangrove seedlings are left on the shore!

Changi faces the mouth of the Johor River.
With the recent massive floods in Johor, there must be a lot of water rushing down towards the Johor Straits. Floating in the flood waters, mangrove seedlings.
On the horizon, Pulau Tekong and behind it the mouth of the Johor River.
This beach, like others managed by NParks, is cleaned every day. So every time I come to the shore, I know I am probably looking at debris washed up by the most recent tide.
Hard at work clearing up the debris on the shore.
The cleaning doesn't go right to the end of the beach. It seems to end where the Park ends. Here, we can more clearly see the debris lines left by the tides.
Among the tangle of propagules of common mangroves, signs of rare ones! I saw a few calyx of the Critically Endangered Bakau mata buaya (Bruguiera hainesii), and several propagules of the Endangered Lenggadai (Bruguiera parviflora).
I saw a handful of calyx of the Critically Endangered Tumu berau (Bruguiera sexangula) and a few with the propagule still attached.
I saw several propagules of the Vulnerable Tengar putih (Ceriops tagal).
I also saw some broken off bits of mangrove trees and shrubs. Including this bit of the Endangered Teruntum (Lumnitzera sp.).
I still have no idea what these fruits/seeds are. There were a lot of them.
I also came across several pink propagules. I remember Dr John Yong's talk where he explains that this happens when the mother mangrove tree is exposed to pollution.
Besides a handful of pink propagules, I also saw a yellow one.
I noticed something interesting too. While near the shore, the propagules float horizontally...
But in deeper water, they float vertically! Here's a line of propagules floating upright.
I tried to take photos of the propagules underwater.
They are floating with the leaf-bearing tip facing up, and the root-bearing tip facing down. All ready to land and grow up into a tree!
Several different kinds of propagules floating vertically.
I didn't come across many dead fishes. These were the only big ones I saw over the week of trips.
Washed ashore were a few creatures like the Black sea urchin (Temnopleurus sp.) and a white sea cucumber. There were not many creatures dead or alive washed up with the debris.
This mangrove snail, the Red chut-chut (Cerithidea obtusa), was clinging to a piece of trash. Flushed down with the flood?
I wasn't the only one prowling on the shore checking up on the debris. The debris line may provide titbits for shore birds and other animals.
I didn't see any freshwater plants or animals among the debris. Or large numbers of dead sea creatures. Floods can have some less happy impacts such as the mass deaths at Chek Jawa in 2007. Let's hope for the best. And meanwhile, appreciate the gift of the flood of mangrove seedlings!

2 comments:

  1. << I still have no idea what these fruits/seeds are. There were a lot of them. >>

    Are the roundish fruits in your photo apple-sized ? If yes, they look very much like Cerbera odollam (ie. the common Pong Pong). In contrast, Cerbera manghas (Sea Mango) produces ovoid (ie. egg-shaped) fruits.

    These ones appear to be on the cusp of ripeness when they were prematurely detached from the mother tree (perhaps by heavy rain/strong wind) -- beneath the thin papery peel, pulp remnants & hints of the fibrous exocarp (husk) can be seen. Under normal circumstances, the fruit loses its relatively thin outer layer of pulp upon full maturity -- ie. the naturally-dehisced pulp-free fruits with air-exposed brown/blackened husk that we typically see on the ground or washed up on banks/shores.

    And if you were to open the fruits up, you would find rather unusual large woody seeds that are raised on one side & flat on the other, & each with a short tail-like extension -- thus somewhat resembling a big 3D comma or a PC mouse.

    Thanks for the interesting photographic inventory of the natural debris & the flotsam & jetsam. The floating mangrove propagules were aligned in the same off-vertical direction -- was there a significant tidal current ?

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  2. Thanks Pat for sharing so much about the mystery fruits. They were about 4cm in diameter. Some seemed to have split into two. The fruits were not woody and seemed fleshy. But I didn't cut any open. Perhaps I shall.

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