|Scientific Name:||Osbornia octodonta|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Ellison, J., Koedam, N.E., Wang, Y., Primavera, J., Jin Eong, O., Wan-Hong Yong, J. & Ngoc Nam, V.|
|Reviewer/s:||Polidoro, B.A., Livingstone, S.R. & Carpenter, K.E. (Global Marine Species Assessment Coordinating Team)|
This species is relatively widespread, but is uncommon. It is threatened by the loss of mangrove habitat throughout its range, primarily due to extraction and coastal development, and there has been an estimated 23% decline in mangrove area within this species range since 1980. Mangrove species are more at risk from coastal development and extraction at the extremes of their distribution, and are likely to be contracting in these areas more than in other areas. It is also likely that changes in climate due to global warming will further affect these parts of the range. Although there are overall range declines in many areas, they are not enough to reach any of the threatened category thresholds. This species is listed as Least Concern.
|Range Description:||This species has a disjunct distribution and is found in eastern Malaysia, Indonesia, the Philippines, and Palau It is also in Northwest Australia, Northeast Australia, Papua New Guinea.|
Native:Australia; Indonesia; Malaysia; Palau; Papua New Guinea; Philippines
|FAO Marine Fishing Areas:||
Indian Ocean – eastern; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species has a patchy distribution and is uncommon. Although there is no species specific population information, it can be assumed that there are areas of population decline throughout its range due to coastal development.|
|Habitat and Ecology:||It is also found in sandy soils at river mouths and mid-high intertidal. It lives in high shore areas and on rocky shores, and is not tolerant of fresh water. This species has multiple stems and is a hardy species, but is slow growing. This species exists in stands of shrubs and small trees up to five metres.|
Although local estimates are uncertain due to differing legislative definitions of what is a 'mangrove' and to the imprecision in determining mangrove area, current consensus estimates of mangrove loss in the last quarter-century report an approximately 23% decline in mangrove areas in countries within this species range since 1980 (FAO 2007).
All mangrove ecosystems occur within mean sea level and high tidal elevations, and have distinct species zonations that are controlled by the elevation of the substrate relative to mean sea level. This is because of associated variation in frequency of elevation, salinity and wave action (Duke et al. 1998). With rise in sea-level, the habitat requirements of each species will be disrupted, and species zones will suffer mortality at their present locations and re-establish at higher elevations in areas that were previously landward zones (Ellison 2005). If sea-level rise is a continued trend over this century, then there will be continued mortality and re-establishment of species zones. However, species that are easily dispersed and fast growing/ fast producing will cope better than those which are slower growing and slower to reproduce.
In addition, mangrove area is declining globally due to a number of localized threats. The main threat is habitat destruction and removal of mangrove areas. Reasons for removal include cleared for shrimp farms, agriculture, fish ponds, rice production and salt pans, and for the development of urban and industrial areas, road construction, coconut plantations, ports, airports, and tourist resorts. Other threats include pollution from sewage effluents, solid wastes, siltation, oil, and agricultural and urban runoff. Climate change is also thought to be a threat, particularly at the edges of a species range. Natural threats include cyclones, hurricane and tsunamis.
|Conservation Actions:||There are no conservation measures specific to this species, but its range may include some marine and coastal protected areas. Continued monitoring and research is recommended, as well as the inclusion of mangrove areas in marine and coastal protected areas.|
Duke, N. 2006. Australia's Mangroves. The authoritative guide to Australia's mangrove plants. University of Queensland, Brisbane, Australia.
Duke, N.C., Ball, M.C. and Ellison, J.C. 1998. Factors influencing biodiversity and distributional gradients in mangroves. Global Ecology and Biogeography Letters 7: 27-47.
Ellison, J.C. 2005. Holocene palynology and sea-level change in two estuaries in Southern Irian Jaya. Palaeogeography, Palaeoclimatology, Palaeoecology 220: 291-309.
FAO. 2007. The World's Mangroves 1980-2005. FAO Forestry Paper 153. Forestry Department, Food and Agriculture Organization of the United Nations (FAO), Rome.
IUCN. 2010. IUCN Red List of Threatened Species (ver. 2010.2). Available at: http://www.iucnredlist.org. (Accessed: 29 June 2010).
Robertson, A.I. and Alongi, D.M. 1992. Tropical Mangrove Ecosystems. American Geophysical Union, Washington, DC.
Spalding, M.D., Blasco, F. and Field, C.D. (eds). 1997. World Mangrove Atlas. The International Society for mangrove Ecosystems, Okinawa, Japan.
|Citation:||Ellison, J., Koedam, N.E., Wang, Y., Primavera, J., Jin Eong, O., Wan-Hong Yong, J. & Ngoc Nam, V. 2010. Osbornia octodonta. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 10 December 2013.|
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