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seagrass lagoon

Seagrass lagoon
The calm and shallow lagoon between the shore and the sand bar is ideal for seagrass. Seagrasses need sunlight to carry out photosynthesis and thus cannot grow too deep. Seagrasses have shallow roots and thus may not grow well where the waves and currents are too strong. The presence of seagrasses provides a unique and important habitat for other marine plants and animals.

Miniature forest : The underground stems and roots of seagrasses form a mat which stabilises the ground, while their leaves slow the water flow and thus help keep sediments down. In the stabilised ground, many burrowing creatures make their homes. The meadows of seagrass leaves create a miniature underwater forest. A host of small plants and animals thrive in the thickets. Many animals that live among the seagrass are not adapted for fast swimming (e.g., the seahorse and filefish).

Mating in the meadows: The lagoon appears to be a favourite breeding ground for some sea creatures. Often, the only signs they leave behind are strange egg cases.

Seagrass nursery: With lots of shelter and food, the seagrass meadows are also an ideal nursery for young sea creatures to grow in relative safety. Some commercially important fish and prawns spend the early stages of their life in sheltered places like Chek Jawa. They only venture into deeper waters when they are large enough.

Seagrass salad? Few creatures have the digestive system to eat living seagrasses. Creatures that eat mainly seagrass include the green turtle (Chelonia mydas) and the dugong (Dugong dugon).

However, seagrasses do provide food in other ways. Living seagrasses provide a surface for tiny algae to grow (these are called epiphytic algae). The algae are eaten by tiny grazers such as snails. When seagrasses die, their decaying leaves contribute to the detritus that many sea creatures feed on.

First Grass: Some seagrasses are pioneer species, that is, they are among the first plants to establish themselves in an area. They pave the way for other plants and animals to settle. In some places, pioneer species include Spoon seagrass and Needle seagrass.

Human uses: Some traditional uses for seagrasses include as roof thatching, stuffing in mattresses, woven into baskets and made into fibres used for fishing nets, mats and other household products. Seagrasses were also used as fertiliser. In some coastal areas of the Philippines and Australia, the natives eat the fruit of the tape seagrass (Enhalus acoroides). It is quite large (4-6cm) and is said to taste like water chestnuts.

Status and threats: Seagrass habitats are destroyed by reclamation and development of intertidal and coastal areas. They are also affected by pollution, oil spills and activities along the coast that stir up sediments and smother the seagrass. Boating activities and dredging can also damage seagrass meadows.

The seagrass lagoon

Egg capsules of a cuttlefish

The black capsules are transparent after the babies hatch

See also ...
What are seagrasses?

Links
Survey of Seagrasses of Chek Jawa: preliminary findings.
PREDICT Prediction of the Resilience and Recovery of Disturbed Coastal Communities in the Tropics (SE Asia) page on the University of the Balearic Islands website: technical abstracts and information on adaptations of seagrasses and the impact of human activity on seagrass habitats.
The Western Australia Seagrass Web Page by Mike van Keulen, Murdoch University Western Australia: lots of details for the layman including what are seagrasses, their ecological significance and human uses, and links to yet more sites.
Marine habitats on the Queensland Parks and Wildlife Service website: click on the seagrass link for lots of details for the layman including more about seagrass, its ecological role and economic uses.
The Seagrass Beds on the Coastal Biodiversity in Ranong, Thailand website: brief introduction to the seagrass habitat and its inhabitants in some parts of Thailand, with photos and links.
Seagrass Beds: A Valuable Ecosystem by Ann Hayden on Reef Briefs: a brief introduction with photos.
Learning about Seagrasses on the Florida Department of Environmental Protection website: lots of easy info on seagrasses, their economic contributions, threats to them.
About Australian Seagrasses on CSIRO Marine Research website: fact sheet on status and threats to seagrasses in Australia.
Submerged Aquatic Vegetation on the Chesapeake Bay Program website: fact sheet on role and function of submerged aquatic vegetation including seagrass, and links to species in the bay.
Seagrass-not just another seaweed on the Queensland Parks and Wildlife Service website: introduction to seagrass, economic and ecological value.

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.
Tan, Leo W. H. & Ng, Peter K. L., 1988. A Guide to Seashore Life. The Singapore Science Centre, Singapore. 160 pp. online version
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.
Ong, Jin Eong & Gong, Wooi Khoon (eds.), 2001. The Encyclopedia of Malaysia (Vol. 6): The Seas. Didier Millet, Malaysia. 144 pp.

a companion website to the chek jawa guidebook website©ria tan 2003 www.wildsingapore.com

a companion website to the chek jawa guidebook
website©ria tan 2003 www.wildsingapore.com