|Scientific Name:||Avicennia germinans|
|Species Authority:||(L.) L.|
Avicennia nitida Jacq.
Avicennia tomentosa Jacq.
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Ellison, A., Farnsworth, E. & Moore, G.|
|Reviewer/s:||Polidoro, B.A., Livingstone, S.R. & Carpenter, K.E. (Global Marine Species Assessment Coordinating Team)|
Although black mangroves are threatened by habitat conversion, pollution, hurricanes and other threats, which have resulted in declines throughout the wider Caribbean region, total mangrove habitat loss within this species range over the last 25 years is estimated to be 17%. It is listed as Least Concern. However, this species should be carefully monitored, as it is difficult to restore and rates of decline maybe be increasing in some areas.
|Range Description:||This species is probably the most widespread neotropical mangrove. It is reported from the eastern tropical coasts of North and South America ranging from southern Florida and Bermuda, 32°20' to Atafona, Brazil, 21°37' and all Caribbean Islands (status on Anguilla is unknown).
It has been noted in a discontinuous distribution on the Pacific coast of South America from Puerto Lobos, Mexico (30°15') south to Piura River, Peru (5°32') (de Lacerda 2002) including the Galapagos Islands, Cocos and Malpelo Islands.
It is also noted from West Africa (Angola, Benin and Togo, Cameroon, Congo, Côte d'Ivoire, Democratic Republic of the Congo, Equatorial Guinea, Gabon, Gambia, Ghana, Guinea, Guinea-Bisau, Liberia, Mauritania, Nigeria, Sao Tomé and Principe, Senegal, and Sierra Leone.
The distribution of this species in Brazil is somewhat in question as the species may be mis-identified as A. germinans when in fact it is A. schaueriana (Tomlinson 1995).
Native:Angola (Angola); Antigua and Barbuda; Bahamas; Barbados; Belize; Benin; Bermuda; Brazil; Cameroon; Cayman Islands; Colombia; Congo; Congo, The Democratic Republic of the; Costa Rica; Côte d'Ivoire; Cuba; Dominica; Dominican Republic; Ecuador; El Salvador; Equatorial Guinea; France; French Guiana; Gabon; Gambia; Ghana; Grenada; Guadeloupe; Guatemala; Guinea; Guinea-Bissau; Guyana; Haiti; Honduras; Jamaica; Liberia; Mauritania; Mexico; Montserrat; Netherlands Antilles; Nicaragua; Nigeria; Panama; Peru; Saint Kitts and Nevis; Saint Lucia; Saint Vincent and the Grenadines; Sao Tomé and Principe; Senegal; Sierra Leone; Suriname; Togo; Trinidad and Tobago; Turks and Caicos Islands; United States; United States Minor Outlying Islands; Venezuela, Bolivarian Republic of; Virgin Islands, British
|FAO Marine Fishing Areas:||
Atlantic – eastern central; Atlantic – southeast; Atlantic – southwest; Atlantic – western central; Pacific – eastern central; Pacific – southeast
|Range Map:||Click here to open the map viewer and explore range.|
Genetic studies of Avicennia are numerous as microsatellite loci, RAPDs, and AFLPs have been developed for this species (Ceron-Souza et al. 2006). Eastern and western Atlantic provenances of Avicennia show significant genetic differentiation, as indicated by leaf chemistry (Dodd and Bousquet-Melou 2000). Studies to date show well-defined genetic structure differentiating western Atlantic from Pacific populations across the isthmus of Panama (Dodd et al. 2002) and among populations sharing a coastline (Ceron-Souza et al. 2005).
Population information for this species in a number of areas:
Mouth of Lostman?s River in Everglades National Park, Florida, U.S. 209 individuals counted over 6 transects totaling 0.26 ha (McCoy et al. 1996). Cockroach Bay (part of Tampa Bay, Florida, U.S.) contains 537 hectares of mangroves and 120 trees per ha (Dawes et al. 1999) of this species were recorded. In Laguna de Celestun, Yucatan, Mexico, combined data for A. germinans, R. mangle and L. racemosa basal area ranges from 21 square meters/ha to 36 square meters/ha (Herrera-Silveira and Ramirez-Ramirez 1998). In Bonaire, Netherlands Antilles: 0.50 tree/square meter (De Meyer, 1998). Parque Nacional Morrocoy, Venezuela: 68% R. mangle, 29% L. racemosa, 8% A. germinans, 1% unidentified total tree density 348 trees/0.1 ha (Bone et al. 1998).
In Cartagena and Barbacoas Bays (Calderón-Sáenz 1984) and Port Royal mangal, this species grows in a mixed zone of R. mangle, A. germinans and L. racemosa that is bordered by a dense monospecific stand of R. mangle and a monospecific stand of C. erectus. (Alleng 1998). In Bahía Las Minas on the Caribbean coast of Panama, there are 1,200 ha of mangroves, which is about 0.3% of the total mangroves in Panama (Duke et al. 1997). This species can dominate sites further inland in Belize where the soil salinity increased through evaporation (Murray et al. 2003).
|Habitat and Ecology:||
This species typically grows in the intertidal regions of sheltered tropical and subtropical coasts (Saenger 2002) and dominates the zone proximal to open water (McKee 1995). It tends to be found in the mid to high intertidal region, and is infrequently found at the seaward margin (Ellison and Farnsworth 1993, Tomlinson 1994, Sherman et al. 2001). Seedlings are quite tolerant of salinity (up to 900 mol/m3; Suarez and Medina 2005), expecially compared to other neotropical mangroves, and can occupy hypersaline areas (Cardona-Alarte et al. 2006). However, mortality increases and relative growth rate decreases at high salinity values (Suarez and Medina 2005).
Where it occurs, Avicennia often achieves the highest importance values and basal area (Murray et al. 2003), becoming the dominant species in the stand. Avicennia has the broadest temperature tolerance of all neotropical mangroves; however, freezing events have damaged extensive stands (Everitt et al. 1996); some recovery is possible. Avicennia responds negatively to drought (Sobrado 1999). Growth and survival of Avicennia germinans is also reduced when it competes with Spartina alterniflora (the dominant grass at the mangrove-salt marsh interface at the northern edge of the mangrove's range; Patterson et al. 1993).
Avicennia germinans provides critical habitat for several organisms, including crabs (Uca rapax, Sesarma curacoaoense, Aratus pisonii; Warner 1969). 104 species of birds are associated with Avicennia stands in Panama, with significant divergence among stands (Lefebvre and Poulin 1997); nesting habitat for Florida Prairie Warblers and Cuban Yellow Warblers (Prather and Cruz 1995).
Avicennia is important for pollinators; regarded as a source of honey for local Apis mellifera populations (Little and Wadsworth 1964).
Black mangroves are threatened by habitat conversion, pollution, hurricanes and other threats, which have resulted in declines throughout the wider Caribbean region. 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 17% 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.
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.
For Avicenna germinans, mangrove tree planting and silviculture can be used to restore previously stripped areas or to help timber production and to create and protect reserves (Saenger 2002). Restoration of Avicennia is being pursued in Louisiana (Willis et al. 2005), Florida (Milano 1999, McKee and Faulkner 2000, Milbrandt and Tinsley 2006), Mexico (Toledo et al. 2001), Costa Rica (Lewis and Marshall 1998) and Colombia (Elster 2000). See the general review by Lewis (2005) for further information. Effectiveness of habitat restoration and success of replantings with A. germinans needs to be assessed; it may be the most promising species for afforesting hypersaline areas.Most seedlings die during natural recruitment events and restoration is challenging.
Demographic modeling could also be useful to establish a minimum viable population size for A. germinans. Evidence from Florida suggests that invasive species negatively impacts A. germinans, more research is recomended. The studies of the uses and cost/benefit analysis are needed for more areas along Atlantic and Caribbean shores and impacts of harvesting on populations. Expand GIS mapping and remote sensing projects and utilize new Landsat and IKONOS technology to do species-based, landscape-level monitoring of deforestation (Kovacs et al. 2005).
|Citation:||Ellison, A., Farnsworth, E. & Moore, G. 2010. Avicennia germinans. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 17 April 2014.|
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