Seagrasses are the only flowering plants (monocotyledonous Angiosperms) that have adapted themselves to living in marine and estuarine habitats, and are submerged most of the time. They are rooted in sediments on the sea bottom, with shoots appearing above the substrate. Seagrasses occurred at 78 sites scattered in the west and east coasts of Peninsular Malaysia and in Sabah and Sarawak in East Malaysia. They are usually found along the coasts growing in association with shallow inter-tidal, mangroves, coral reefs, semi-enclosed lagoons and shoals. In these habitats, seagrass beds or meadows have distinct species assemblage completely adapted to the submerged life. There are fourteen major species of seagrasses recorded in Malaysia: Enhalus acoroides, Halophila beccarii, H. decipiens, H. ovalis, H. minor, H. spinulosa, Halodule pinifolia, H. uninervis, Cymodocea rotundata, C. serrulata, Thalassia hemprichii, Syringodium isoetifolium, Ruppia maritima and Thalassodendron ciliatum. Although seagrasses make up only a small portion of the marine ecosystem, the physical settings and their interactive community within and from outside account for their high diversity and ensure survival of an assortment of vertebrates (fish), invertebrates (shrimps, starfish, sea cucumbers, bivalves, gastropods), and seaweeds. Seagrass form the food and habitats for the vulnerable dugongs or sea cows (Dugong dugon), seahorses (Hippocampus spp.) and endangered green turtles (Chelonia mydas), and for other fish, and also a feeding ground for seasonal migratory birds, Egretta garzetta. Seagrasses provide conditions for the growth and abundance of invertebrates and fish that many local coastal communities collect and catch for their livelihood. Seagrass ecosystems are sources of food and yet they are continually threatened by human activities, causing their degradation and possible habitat loss. The purpose of this review is to give information on the significant linkages of seagrasses with the coastal inhabitants and to suggest recommendations for the protection and conservation of this important ecosystem and the associated resources.
Seagrasses are not true grasses; they are submersed monocotyledonous plants and form patches in dense extended coastal beds or meadows. Seagrasses, just as terrestrial plants, constitute complex and productive ecosystems occurring both in temperate and tropical seas. Healthy seagrass communities provide food for herbivores; habitats and nurseries for invertebrates, fish, turtles and birds; stabilize sediments and recycle nutrients, and are also highly productive (Dawes et al., 1995). Seagrass communities, with their structural complexity, contribute to the productivity and biodiversity of their areas (Simenstad, 1994), just as terrestrial ecosystems, (e.g. tropical rain forests, or that of aquatics like mangroves, and coral reefs) do.
In Malaysia, along its 4800 km coastline, stretching along the Malay Peninsula, Sabah and Sarawak and bounding much of the southern part of the South China Sea, are various environments with coastal habitats; mangroves, coral reefs and seagrasses. In general along the mainland, coastal areas between mangroves and corals (from low tide level to the coral reef fringe) form the habitats for seagrasses. Seagrasses are also found at off-shore islands with fringing corals where they inhabit the outer region between the corals and the semi-open sea.
The habitats where seagrasses grow are under greater threat today than ever before. Increasing numbers of people are utilizing the coasts and adjacent waters for various activities which have been accompanied by major coastal developments. This paper presents information on the distribution and significance of seagrass ecosystems in Malaysia, and suggests recommendations for the protection and conservation of this important ecosystem.
This paper reviews the status of distribution and significance of seagrass ecosystems in Malaysia through a study of available information produced over the past decade (1994 to 2004). This literature review is part of a research project on the inventory of marine plants and associated organisms under the Intensification in Priorities Research 6, 7 and 8 funded by the Ministry of Science, Technology and Environment, Malaysia. The information presented in this review covers distribution, taxonomy, diversity, utilization and, natural and human activities. By synthesizing this information, it is hoped that this review represents a more informed evaluation of the seagrass ecosystems and their significance in Malaysia.
In sheltered coastal water bodies, seagrasses are found in association with shallow inter-tidal pools (Norhadi, 1993; Japar Sidik et al., 1999a; Muta Harah et al., 1999), semi-enclosed lagoons (Muta Harah et al., 2000), coral reef flats (Japar Sidik et al., 1995, 2001) and also sub-tidal zones (Japar Sidik et al., 1996). The inter-tidal seagrass community is not entirely submersed, but inundated twice daily with the rise of the tides. There are 78 seagrass beds scattered throughout Peninsular and East Malaysia. In terms of aerial distribution, seagrasses range from isolated patches to continuous coverage over several hectares (Japar Sidik and Muta Harah, 2002). The most developed and diverse communities are found in the south and east coasts of Peninsular Malaysia, Sabah and Sarawak, where urbanization is minimal. With different communities (Table 1) and environmental parameters, seagrass beds are site specific. Figure 1 illustrates the major sites of seagrass ecosystems and utilization by coastal inhabitants.
Distribution in Peninsular Malaysia
Along the west coast, patches of mixed species seagrass beds grow on substrates from the sandy-mud of Tanjung Rhu in the extreme northern region along the coast of P. Langkawi (P. = pulau or island), Kedah to sand-covered corals of Teluk Kemang, Negri Sembilan extending to as far as P. Serimbun, Malacca (Japar Sidik et al., 2001). The Teluk Kemang is the only area in the mainland Peninsula that has inter-tidal seagrass beds on reef platforms. In the southern region, the calcareous sandy-mud sub-tidal shoals of Tanjung Adang Darat, Tanjung Adang Laut and Merambong at depths of 2 to 2.7 m support nine species of seagrasses (Table 1), the highest species number for any locality in either Peninsular Malaysia or Malaysia (Japar Sidik et al., 1996). Most of the inter-tidal areas of the eastern coastline are fringed with sandy to rocky areas and therefore devoid of seagrasses. Beds of two species, Halophila beccarii-Halodule pinifolia inhabit the fine sand substrate of the shallow inland coastal lagoons from Pengkalan Nangka, Kelantan to Paka, Terengganu while Halodule pinifolia-Halophila ovalis inhabit similar substrate type of Gong Batu and Merchang. A monospecific bed of H. pinifolia is found at Kemasik, Terengganu. Monospecific beds of Halodule pinifolia or Halophila minor or Halophila decipiens (e.g. at P. Redang, Muta Harah et al., 2003a) as well as mixed species seagrass beds, occur in the waters of the off-shore islands with fringing coral reefs of P. Sibu, P. Tengah, P. Besar, P. Tinggi, P. Redang and P. Perhentian (Table 1, Japar Sidik et al., 1995; Muta Harah et al., 2003a) and P. Tioman (Zelina et al., 2000). Seagrasses usually inhabit the outer region between the corals and the semi-open sea.
Distribution in East Malaysia
The west and south-eastern coasts of Sabah harbour supports mixed species seagrass beds in substrates ranging from sand, muddy-sand to coral rubble of the inter-tidal zone down to a depth of 2.5 m. There are six areas of inter-tidal mixed associations of seagrass and coral reef along the west coast at Bak-Bak, Tanjung Mengayau, Sepangar Bay and P. Gaya. The four isolated off-shore islands of P. Maganting, P. Tabawan, P. Bohey Dulang and P. Sipadan along the south-eastern coast have sub-tidal seagrasses growing on coral rubble (Norhadi, 1993; Japar Sidik et al., 1997; Japar Sidik et al., 1999a, b, 2000; Josephine, 1997; Figure 1).
In Sarawak, records indicated the presence of seagrasses, Halophila beccarii, collected in Sungai Bintulu (den Hartog, 1970) and Halophila decipiens at P. Talang Talang, Semantan (Phang, 2000). A survey in 2003 discovered an extensive inter-tidal beach front of Punang-Sari-Lawas river estuary, Sarawak (Figure 1), comprising sandy flatland transversed by shallow channels and intermittent pools harbouring five seagrass species (Table 1, Muta Harah and Japar Sidik, 2003b).
Table 1 summarizes the occurrence of seagrass species in the different areas. Malaysia has a total of 14 seagrass species belonging to 8 genera (Table 1, Figure 2). Two other species, Thalassodendron ciliatum (Phang, 2000) and Ruppia maritima (Burkill, 1935) are not included in Table 1 as they are rare in occurrence.
Several localities along the coasts of Malaysia supported well-developed seagrass communities and a large proportion (40%–71%) of all known seagrass species in Malaysia. The Teluk Kemang and Tanjung Adang-Merambong shoals of the Peninsular Malaysia, P. Gaya, Sabah and Punang-Sari-Lawas river estuary, Sarawak has a greater diversity of seagrass (Table 1).
Significance of seagrass ecosystem
Direct utilization of seagrasses is rare. The fibers from softer part of tropical eel grass, E. acoroides can be made into fishing nets (Burkill, 1935) and the leaves were one of the chief foods of the dugong (Ridley, 1924), once common in Malaysia. Ruppia maritima plants are used in fish ponds to promote the aeration of water, and the milk fish (Chanos sp.) feeds on it (Burkill, 1935). Human consumption of seagrass is not entirely confined to the past; seeds of E. acoroides are consumed by the coastal communities of Sungai Pulai, Johore. The nutritional value of the flour derived from E. acoroides seeds is comparable to that of wheat and rice flour in terms of carbohydrate, protein and energy values, and surpasses these other types of flour in calcium, iron and phosphorus (Montano et al., 1999).
Human habitation near or adjacent to seagrass areas is common in Malaysia. The dwellers are dependent on the natural fisheries. They also belong to the seagrass ecosystem; at least at the subsistence level, seagrasses are a source of food to the community. The economic contribution of seagrass associated resources though harvesting is difficult to quantify as there are no records or figures available. Here we are providing information on the significant linkages of the seagrass ecosystem as a service to the local coastal inhabitants and other users (Table 2).
Aquatic life can be diverse in the various seagrass areas of Malaysia. Fishes are by far the most diverse and abundant vertebrates, and seagrass habitat provides an important refuge for many species. The dense seagrass beds of the sub-tidal shoals of Tanjung Adang-Merambong, Johore, Pengkalan Nangka, Kelantan and Paka shoal, Terengganu support many juvenile and adult fishes, and prawns. In Tanjung Adang-Merambong, between 70–76 species of fish in 41 families have been observed in seagrass beds and the adjacent mangrove areas (Sasekumar et al., 1989). Of these, 35 fish species are of commercial importance, among them; Ilisha spp., Stolephorus indicus, Thryssa hamiltoni, Hippocampus spp., Lates calcarifer, Lutjanuschrysotaenia, Plotosus canius, Apolynemus sextarius, Rastrelliger kanaqurta, Siganus guttatus, S. javus, Siganus sp., Epinephalus sp. and Therapon spp. (Arshad et al., 2001). The rest are under low-grade fish category and are consumed locally. Seahorses species (e.g. Hippocampus kuda, status: vulnerable VU A4cd) are very much in demand locally and abroad for Chinese traditional medicine. Species of commercially important prawns; Alpheus sp., Macrobrachium sp., Penaeus indicus, Penaeus merguiensis, Penaeus monodon, Penaeus semisculcatus, Parapeneopsis sp., Metapeneopsis barbeensis, Metapenaeus sp., Lucifer sp. and Acetes sp. and stomatopods (Oratosquilla sp.) have been recorded from the seagrass areas. Other crustaceans include crabs: Dorippe sp., Hemigrapsus sp., Parthenope longimanicus, Portunus pelagicus, Scylla serrata, Thalamita sp., Matuta sp. and horse-shoe crab, Carcinoscorpius rotundicauda have been observed (Arshad et al., 2001). In Pengkalan Nangka, Kelantan and Paka shoal, Terengganu, fishes such as Caranxsexfasciatus, Leiognathusequulus, Lutjanusrusselli, Mugilcephalus, Periophthalmus sp., Scatophagusargus, Tylosuruscrocodilus and Scomberoideslysan are found in abundance (Muta Harah, 2001). In all the areas mentioned, traditional capture fishing is done through the use of gill nets, drift nets, cast nets, pull nets or hook and lines. Juvenile and young stages of economically important fish species are also captured. Catch is either sold in fresh state in local markets or salted or sundried for home consumption. The same seagrass areas during low tide are used as collection and gleaning sites for gastropods (Lambis lambis, Strombus canarium) and bivalves (Gafrarium sp., Geloina coaxans, Meretrix meretrix, Modiolus sp., M. senhausii, Hiatula solida). Common echinoderms e.g. Archaster sp., Astropecten sp., Protoreaster nodusus, Macrophiothrix sp. and sea cucumbers; Phyllophorus sp., Pentacta quadrangularis and Mensamaria intercedens though present, were not harvested. Although seagrass ecosystems provide services, it becomes evident that seagrasses are a vulnerable resource. Small-scale destructive fishing by pull net at Pengkalan Nangka, Kelantan, Paka shoal, Terengganu, and harvesting of bivalves, Hiatula solida, Meretrix meretrix (Figure 3) and Geloina coaxans at Pengkalan Nangka, Kelantan, have been shown to cause mechanical damage, reduce seagrass cover and retard the spread and colonization of seagrasses (Japar Sidik and Muta Harah, 2003).
In Sabah, most seagrass and coral reef associated ecosystems are gleaning sites for food collection. Uncontrolled collection of flora such as Caulerpa spp., Gracilaria sp. and fauna such as sea cucumbers, gastropods and bivalves (e.g. Sepangar bay, P. Gaya, Figure 3) and illegal fishing (e.g. P. Selingan, P. Bakungan Kecil) with explosives are among the major causes of damage to coral reefs and associated seagrasses. In Sarawak, the known seagrass area of Punang-Sari-Lawas river estuary is a fishing ground for the traditional fishermen. The fish Ilisha elongata (locally known as Tahai) harvested from the seagrass area and adjacent areas is smoked and sold in the market.
Seagrass, e.g. Halodule pinifolia, when locally abundant can improve water quality of a particular environment. Such water bodies have then been utilized for fish (Lates calcarifer and Epinephelus sexfasciatus) cage farming, for example at Pengkalan Nangka, Kelantan, and Gong Batu, Terengganu, which started in 1991, or oyster (Saccostrea cucullata) farming as in Merchang since 1998 (Japar Sidik et al., 1999a).
Very rarely does the seagrass ecosystem have a large number of mammals or reptiles. Dugong dugon (status: vulnerable, VU A1cd) and Cheloniamydas (green turtle, status: endangered, EN A1bd) are found to be associated with and feed on seagrasses. Dugongs were still common in the 1950s and later became rare because they were hunted for their meat and hide (Holttum, 1954). Presently dugongs are found mostly in areas with abundant seagrasses such as P. Sibu, P. Tengah, P. Besar and P. Tinggi on the east coast and around Tanjung Adang-Merambong shoals of Sungai Pulai, Johore (Japar Sidik and Muta Harah, 2002). In Sabah, sighting reports and surveys conducted from interviews on fishermen and local villagers have indicated that dugongs are encountered occasionally in Tunku Abdul Rahman Marine Park (Jaaman, 2000). Other areas with possible viable populations are the shallow coastal waters from Semporna, Kudat, Kota Kinabalu, Sepangar bay, Sabah (Jaaman et al., 1997; Jaaman, 1999) to Lawas, Sarawak. Green turtles are abundant in Cagar Hutang, P. Redang, Peninsular Malaysia and in P. Selingan and P. Bakungan Kecil, Sabah. These areas are the nesting ground of turtles and the presence of seagrass meadows in the vicinity may serve as feeding ground.
Many bird species occasionally land on exposed seagrass areas along the shores. Wading birds, such as some of the herons and egrets, Egrettagarzetta are occasionally seen feeding in seagrass areas e.g. Pengkalan Nangka, Kelantan, Tanjung Adang-Merambong shoals, Johore.
Seagrass protection and conservation
Seagrass ecosystems are teeming with life, providing essential habitat for associated fauna and algal flora. In addition, given the importance of seagrass as a fisheries habitat, nursery and feeding ground, this relatively lesser known resource must be afforded the same priority as that of well-managed mangroves and corals to provide for future renewable resource utilization, education and training, research, conservation and protection. Seagrasses contribute to the coastal fisheries resources and biodiversity and are valued by the local coastal communities. Continued human activities (Table 2) in the coastal areas threaten and cause degradation and habitat loss.
The protection and conservation of seagrass resources is not confined to managing the seagrass areas themselves. The management of seagrass resources requires efforts directed towards identifying, understanding and solving the natural and man-induced changes to seagrass resources. It is strongly recommended that the seagrass ecosystem, being an integral part of the larger marine ecosystem, be given protection. Those around offshore islands that have been gazetted as marine parks (e.g. P. Redang, P. Perhentian of Terengganu, P. Tioman of Pahang, P. Tengah, P. Besar, P. Sibu, P. Tinggi of Johore) have been given protection as marine parks or reserves under the Fisheries Act 1985. Under part IX, Act 4(1) and (2) of the Fisheries Act 1985, the Minister of Agriculture may order the establishment of any area or part of an area in Malaysian fisheries waters as a marine park or marine reserve in order to:
afford special protection to the aquatic flora and fauna of such area or part thereof and to protect, preserve and manage the natural breeding grounds and habitat of aquatic life, with particular regard to species of rare or endangered flora and fauna;
allow for the natural regeneration of aquatic life in such area or part thereof where such life has been depleted; promote scientific study and research in respect of such area or part thereof;
preserve and enhance the pristine state and productivity of such area or part thereof and
regulate recreational and other activities in such area or part thereof to avoid irreversible damage to its environment.
the limits of any area established as a marine park or marine reserve under subsection (1) may be altered by the Minister and such order may also provide for the area or part of the area to cease to be a marine park or marine reserve.
The question of affording comprehensive protection to marine ecosystems under the present Fisheries Act of 1985 has been the subject of intense scrutiny by marine scientists, government officials and conservationists; the bone of contention being the separation of the land on islands as marine parks and reserves, from the waters surrounding the islands. Under these circumstances, while the authorities have powers to manage and enforce what the marine park laws allow at sea, they have no jurisdiction whatsoever over what happens on land.
This could be resolved based on practices adopted in Sabah Parks and the present trend of promulgating state parks enactments for the protection of ecosystems. At present, the Sabah Parks has under its auspices, three marine protected areas: Tunku Abdul Rahman Marine Parks (part of P. Gaya, P. Manukan, P. Mamutik, P. Sapi and P. Sulug), Pulau Tiga Parks and Turtle Island Parks (e.g. P. Selingan, P. Bakungan Kecil) and all harbour seagrasses. These areas were deemed State Parks under the State Parks Enactment 1984. These parks are protected in their entirety without separating the marine and terrestrial components. Several states in Peninsular Malaysia have promulgated enactments for the procurement of state parks. Johore has instituted the National Parks (Johore) Corporation Enactment 1991, and Terengganu has a Terengganu State Parks Enactment. Concurrent establishing of marine protected areas under both Federal and State Legislations, using both The Fisheries Act 1985 to ensure the protection of the waters surrounding the islands as Marine Parks or Reserves, and State Park Enactments to include the terrestrial component of the marine protected areas as state parks, should be practiced. The above policies can be applied to the management of marine protected areas in most of Peninsular Malaysia, in order to conserve this valuable seagrass ecosystem resource.
We wish to thank Vice-Cancellor, Universiti Putra Malaysia, for encouragement and use of facilities. Our thanks are extended to Prof. Miguel Fortes and to anonymous referees for their valuable comments to improve this manuscript. The research fund provided by The Ministry of Science, Technology and Environment Malaysia, under the ‘Intensification of Research in Priority Areas’ programme is also acknowledged.