|Scientific Name:||Enhalus acoroides|
|Species Authority:||(L.f.) Royle|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Short, F.T. & Waycott, M.|
|Reviewer/s:||Livingstone, S., Harwell, H. & Carpenter, K.E.|
This species is widespread and common within at least part of its range. As this species is restricted to shallow-water habitat (
Enhalus acoroides is widespread in the Indo-Pacific. In the Pacific, it is found from southern Japan to Taiwan to the Philippines, Indonesia, and Malaysia extending throughout the Gulf of Thailand and the coast of Vietnam to Hainan, China. It occurs across insular Southeast Asia to New Caledonia, northern Australia and across Micronesia to the Northern Mariana Islands.
In the Indian Ocean, it is found from Roebuck Bay, northern Australia, extending across the Timor Sea, the south coast of Indonesia, and throughout the Andaman Sea and northern Myanmar. It occurs in southern India, Sri Lanka, and the Lakshadweep Islands. It ranges from the Red Sea south to northern Mozambique, and in the Seychelles.
Native:Australia; Brunei Darussalam; Cambodia; China (Hainan); India; Indonesia; Japan; Kenya; Madagascar; Malaysia; Micronesia, Federated States of ; Mozambique; Myanmar; New Caledonia; Palau; Papua New Guinea; Philippines; Saudi Arabia; Seychelles; Singapore; Sri Lanka; Tanzania, United Republic of; Thailand; United States Minor Outlying Islands; Vanuatu; Viet Nam; Yemen
|FAO Marine Fishing Areas:||
Indian Ocean – eastern; Indian Ocean – western; Pacific – northwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Enhalus acoroides is common and widespread, especially in embayments. Its population trend is declining in a number of locations within its range due to localized threats, and is most likely declining overall.|
|Habitat and Ecology:||
Enhalus acoroides is found in the subtidal zone and is slow to produce new shoots but produces high biomass, being a very large seagrass. The siltier the water, the longer the leaves grow in order to capture more light. It is the only species that releases pollen to the surface of the water in sexual reproduction, which restricts its distribution to intertidal and shallow subtidal areas. It is a slow-growing, persistent species with a poor resistance to perturbation (Green and Short 2003).
Enhalus acoroides is common in the major seagrass areas of Southeast Asia. In Thailand, it occurs in brackish water canals down to the lower intertidal and subtidal zones on mud, muddy sand and sandy coral substrates. In the Gulf of Thailand, it grows on coarse substrate ranging from medium and coarse sand to coral rubble at a depth of 0.5-1.0 m. In Indonesia, E. acoroides grows in a variety of different sediment types, from silt to coarse sand, in subtidal areas or localities with heavy bioturbation. In the Philippines, it colonizes turbid, quiet, protected areas such as bays and estuaries (Green and Short 2003). In Peninsular Malaysia, it is common all around the coast on muddy shores and areas exposed at low tide.
Threats for Enhalus acoroides include coastal development, dredging and marine developments, minor damage from boating and shipping activities, coastal runoff and to some extent trawling activities. This species is found in embayments, it is especially threatened by the creation of fish pens/farming. The species is also threatened by shallow-net trawling and eutrophication. As this species is primarily found in estuaries, shallow lagoons, muddy bays and inside basins, it is often disturbed by vessels and anchorage.
This species is found in a narrow depth range. Therefore this species is especially sensitive to disturbances, including global climate change, such as sea-level rise.
In Kenyan and Tanzanian shores, overexploitation and influences from activities on land (trawling activities, high hotel density in close proximity to the beach, raking, burying and removing seagrass beach cast material, oil spills, and oil pollution) can affect this species (Green and Short 2003).
In India, the natural causes of destruction are cyclones, waves, intense grazing and infestation of fungi and epiphytes, as well as "die-back" disease. Other threats include anthropogenic activities such as deforestation in the hinterland or mangrove destruction, construction of harbours or jetties, and loading and unloading of construction material as well as anchoring and moving of boats, ships, dredging and discharge of sediments, land filling and untreated sewage disposal (Green and Short 2003).
In Thailand, this species is threatened by a combination of illegal fisheries and fishing practices, land-based activities (especially mining), and reduced water quality resulting from upland clearing, development along rivers and destruction of mangrove forests (Green and Short 2003).
In the western Pacific, coastal development, dredging, and marina developments, climate change and associated increase in storm activity, water temperature and/or sea-level rise are all possible threats. In Indonesia, it is threatened mainly by physical degradation such as mangrove cutting and coral reef damage, and by marine pollution from both land- and marine-based resources. Overexploitation of living marine resources such as fish, molluscs and sea cucumbers is also an issue (Green and Short 2003).
In the Philippines, it is threatened by eutrophication, siltation, pollution, dredging and unsustainable fishing methods (Green and Short 2003).
In Japan, threats include industrial developments in coastal regions, land reclamation resulting in loss of vegetation, water pollution, disturbance of habitats caused by trawling, and changes in environmental conditions due to human activities (Green and Short 2003).
This species is included in various conservation and management plans and programs. For example, in Japan this species is listed as Vulnerable on the national Red List. In India, all seagrasses are included in ecologically sensitive marine areas, CRZ-I, which have the highest level of protection (Coastal Regulation Zone Act 1993). In Malaysia, under the Marine Fisheries Act of 1985, seagrasses are protected in marine parks.
Enhalus acoroides is considered in the most recent management plan of the Mombosa Marine National Park and Reserve. Implementation of integrated coastal zone management initiatives have occurred in Tanzania by IUCN, Zanzibar (Menai Bay Conservation Project), Mafia Marine Park (by WWF) and Kinondoni Coastal Area Management Programme (Green and Short 2003).
This species occurs in the seagrass beds in Haad Chao Mai National Park, largest seagrass beds with the highest species diversity for a single area in Thailand. In 1998, the Office of Environmental Policy and Planning in Thailand proposed policies for the management of seagrass resources (Green and Short 2003).
In the western Pacific islands, it is recognized in the need for sanctuaries and protected areas and the concept of traditional or community management of these areas. There are NGOs focused on its conservation and environmental protection integrated with traditional leadership and government agencies, suggesting that conservation measures and the acceptance of enforcement will continue to improve (Green and Short 2003).
This species is included in the Indonesian Seagrass Committee (ISC) draft on Seagrass Policy, Strategy and Action Plan to guide the management of the seagrass ecosystem in Indonesia.
It is particularly important to protect this species from physical disturbance. More data is needed on its potential to recover following disturbance. Little is known about this species' tolerance thresholds to environmental factors (such as salinity, temperature, light, etc).
|Citation:||Short, F.T. & Waycott, M. 2010. Enhalus acoroides. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 11 December 2013.|
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