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Needle
seagrass is common on the edges of the sand bars. It has narrow leaves
up to 15cm long and 3.5mm wide. These emerge from thin rhizomes (underground
stems) which have fine roots. It has tiny flowers and produces seeds
with a hard seed coat.
Needle seeds: The seagrass has
an unusual way of releasing its seeds directly into the sediments
so the seeds are not washed away by the currents. Studies suggest
the seeds can remain dormant for some time. In this way, the seeds
may help re-establish the species if the parent plants are destroyed
by some natural disturbance. However, Needle seagrass tends to spread
more by vegetative growth than through its seeds.
Role in the habitat: Although
tiny, Needle seagrass grows rapidly and densely from its underground
stems. Forming a mat, it traps, builds up, and stabilises sediments.
This allows other seagrasses to establish themselves and provides
a more stable environment for burrowing creatures. On Chek Jawa, Needle
seagrass is commonly found on the seaward side of the sand bars. Preliminary
results of a transact survey shows its distribution in the seagrass
lagoon. Needle seagrass is also one of the seagrasses preferred by
dugongs.
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See
also ...
Seagrasses in general
Links
Halodule
uninervis on the University of Hawai'i website: fact sheet with
photos and diagrams of the seagrass.
Halodule
Picture Index on the University of Hawai'i website: a selection of photos
of various Halodule species found in Hawai'i
Fruits
of the Sea: Seeds of Coastal Seagrasses on the CRC Reef Research Centre
website: brief introduction to the ways seagrasses reproduce and re-establish
themselves if affected by natural disturbances, and how Halodule uninervis
'stores' its seeds in the sediments.
Identifying
seagrasses along the North Queensland Coast on the CRC Reef Research
Centre website: snippets on Halodule uninervis with a diagram
Halodule
spp. on the Hervey Bay Dugong and Seagrass Monitoring Program (Australia)
website: brief fact sheet with diagrams of the seagrass.
Other references
- Calumpong, H.
P. & Menez, E. G., 1997. Field Guide to the Common Mangroves, Seagrasses
and Algae of the Philippines. Bookmark, Inc., the Philippines. 197
pp.
- Hartog, C. Den.
The Sea-grasses of the World, 1970. North-Holland Pub. Co., Amsterdam.
276 pp., 20 pp. of photos.
- Lim, S., P. Ng,
L. Tan, & W. Y. Chin, 1994. Rhythm of the Sea: The Life and Times
of Labrador Beach. Division of Biology, School of Science, Nanyang
Technological University & Department of Zoology, the National University
of Singapore. 160 pp.
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