|Scientific Name:||Bruguiera sexangula|
|Species Authority:||(Lour.) Poir.|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Duke, N., Kathiresan, K., Salmo III, S.G., Fernando, E.S., Peras, J.R., Sukardjo, S. & Miyagi, T.|
|Reviewer/s:||Polidoro, B.A., Livingstone, S.R. & Carpenter, K.E. (Global Marine Species Assessment Coordinating Team)|
This species is widespread and uncommon throughout its range. It is restricted to the middle intertidal regions in larger riverine estuaries and tidal swamps. 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 21% 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 is widespread and found in India, Bangladesh, Brunei Darussalam, China, Taiwan, Indonesia, Malaysia, Myanmar, Philippines, Singapore, Sri Lanka, Thailand, Viet Nam, Northeast Australia, Papua New Guinea, and the Solomon Islands. In China, this species is restricted to Hainan Island, where it is uncommon. It was introduced into Hawaii in 1922.|
Native:Australia; Bangladesh; Brunei Darussalam; Cambodia; China; Christmas Island; India; Indonesia; Malaysia; Myanmar; Papua New Guinea; Philippines; Singapore; Solomon Islands; Thailand; Viet Nam
Introduced:United States Minor Outlying Islands
|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:||This species is uncommon in many parts of its range. In India, this species was found in 30% of 100 sampling sites (Kathiresan 2008). It is common in Sundabands and Orissa, and rare in Andaman Islands and in Kerala. This species occurs in densities of approximately 6 trees/ha in Pagbilao, Philiippines.|
|Habitat and Ecology:||This species is found in intermediate to upstream estuarine zones in middle intertidal regions. It is restricted to larger riverine estuaries and tidal swamps, and prefers a maximum porewater salinity of 33 ppt (Robertson and Alongi 1992). This is a slow-growing species that can grow to 30 m. It is often associated with Sonneratia caseolaris.|
Sea level rise is a major threat, especially to back mangroves that have no area in which to expand. Mangrove species with a habitat on the landward margin may be particularly vulnerable to sea-level rise if owing to coastal development their movement inland is blocked. 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 21% 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. In Fujan province, China this species has been introduced and is grown in plantations to protect coastal regions.|
|Citation:||Duke, N., Kathiresan, K., Salmo III, S.G., Fernando, E.S., Peras, J.R., Sukardjo, S. & Miyagi, T. 2010. Bruguiera sexangula. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 11 December 2013.|
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