Tape seagrass (Enhalus acoroides) is the longest seagrass found on our shores. The leaf blade is 1-2cm wide and can be 1.5m long! Pulau Semakau has vast tracts of Tape seagrass meadows that stretch for kilometres! Tape seagrass is also plentiful at Cyrene Reef.
|Vast meadows of Tape seagrass on Pulau Semakau!|
|The tiny white male Tape seagrass flowers form in a bract that grows at the base of the plant.|
|The large female Tape seagrass flower has large petals and is held on a long stalk. This eventually becomes a hairy fruit!|
Another long seagrass, Serrated ribbon seagrass (Cymodocea serrulata) is abundant on Pulau Semakau as well as Cyrene Reef. It has tiny 'teeth' at the tip of the leaf blade which can only be seen if you look very very closely.
Needle seagrass (Halodule sp.) is long, narrow and well, needle-like. On Chek Jawa and on Cyrene Reef they can be lush and long. Elsewhere, they may be much shorter.
Sickle seagrass (Thalassia hemprichii) is indeed often sickle-shaped. A lush meadow of this seagrass grows on Labrador, the last on our mainland.
|The lush meadows of Sickle seagrass at Labrador is the last on our mainland.|
The Noodle seagrass (Syringodium isoetifolium) is a strange seagrass. Its leaf blade is cylindrical, like plastic tubing! It is commonly seen (so far) only on Pulau Semakau.
There are several species of Halophila seagrasses. Some have oval leaves and thus called Spoon seagrasses. The various species of oval-shaped Halophila are difficult to differentiate in the field, so all of them are generally referred to as Halophila ovalis complex. These seagrasses are the most commonly encountered on many of our shores.
The beautiful Fern seagrass (Halophila spinulosa) is made up of many little leaflets. Usually a bright green, sometimes with a bluish tint, this seagrass is widespread on Chek Jawa.
Singapore is home to the delicate Beccarri's seagrass (Halophila beccarrii). The tiny leaves of this seagrass emerges in a rosette of 4-5 leaves. Elsewhere in the world, this seagrass is considered rare. But it is quite commonly seen on Chek Jawa.
The Hairy spoon seagrass (Halophila decipiens) was only recently discovered on Singapore shores! It was first confirmed in 2008 from specimens collected off Pulau Semakau at a depth of 8m. It has since been sighted at other locations in waters off the Southern islands and also at Changi and Pulau Sekudu!
Are seagrasses important?
Yes they are! Seagrasses form a vital habitat that affects a wide variety of life and influences (and is influenced by) nearby ecosystems such as coral reefs and mangroves.
The meadows of seagrass leaves create a miniature underwater forest. A host of small plants and animals thrive in these thickets. Seagrasses provide shelter for many animals that are not adapted for fast swimming (e.g., the seahorse and filefish). These include juveniles of larger fishes and animals that later move out into deeper waters and include commercially important fishes and sea creatures. Seagrass leaves also provide a place for animals to lay their eggs, and for small animals to settle down.
Few animals can eat seagrasses, because few can digest the cellulose that makes up these plants. Among those that do feed on seagrasses are the Dugong as well as sea turtles such as the Green turtle and Hawksbill turtle.
|A dugong feeding trail!|
Seen at Chek Jawa during TeamSeagrass monitoring!
|A tiny seagrass seahare browses in a 'garden' of tiny lifeforms growing on a seagrass blade.|
According the Seagrass-Watch website, seagrass meadows are considered the third most valuable ecosystem globally. The average value of seagrasses for their nutrient cycling services and the raw product they provide has been estimated at US$ 19,004 per hectare per year (1994). This value would be significantly greater if the other services of seagrasses were included.
MORE about seagrasses on the Seagrass-Watch website and wildsingapore fact sheet.