|Scientific Name:||Dichocoenia stokesii Milne Edwards & Haime, 1848|
|Red List Category & Criteria:||Vulnerable A4c ver 3.1|
|Assessor(s):||Aronson, R., Bruckner, A., Moore, J., Precht, B. & E. Weil|
|Reviewer(s):||Livingstone, S., Polidoro, B. & Smith, J. (Global Marine Species Assessment)|
This species is widespread in the Caribbean and common throughout its range. However, it is particularly susceptible to bleaching, disease, sedimentation, and extensive reduction of coral reef habitat due to a combination of threats. Specific population trends are unknown but population reduction can be inferred from declines in habitat quality based on the combined estimates of both destroyed reefs and reefs at the critical stage of degradation within its range (Wilkinson 2004). Its threat susceptibility increases the likelihood of being lost within one generation in the future from reefs at a critical stage. Therefore, the estimated habitat degradation and loss of 38% over three generation lengths (30 years) is the best inference of population reduction and meets the threshold for Vulnerable under Criterion A4c. It will be important to reassess this species in 10 years time because of predicted threats from climate change and ocean acidification.
|Range Description:||This species occurs in the Caribbean, Gulf of Mexico, Florida (including the Florida Middle Grounds), the Bahamas, and Bermuda.|
Native:Anguilla; Antigua and Barbuda; Bahamas; Barbados; Belize; Bermuda; Bonaire, Sint Eustatius and Saba (Saba, Sint Eustatius); Cayman Islands; Colombia; Costa Rica; Cuba; Curaçao; Dominica; Dominican Republic; Grenada; Guadeloupe; Haiti; Honduras; Jamaica; Mexico; Montserrat; Nicaragua; Panama; Saint Barthélemy; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Vincent and the Grenadines; Sint Maarten (Dutch part); 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 – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species is common, and may be locally abundant in certain habitats and localities.|
There is no species specific population information available for this species. However, there is evidence that overall coral reef habitat has declined, and this is used as a proxy for population decline for this species. This species is particularly susceptible to bleaching, disease, and other threats and therefore population decline is based on both the percentage of destroyed reefs and critical reefs that are likely to be destroyed within 20 years (Wilkinson 2004). We assume that most, if not all, mature individuals will be removed from a destroyed reef and that on average, the number of individuals on reefs are equal across its range and proportional to the percentage destroyed reefs. Reef losses throughout the species' range have been estimated over three generations, two in the past and one projected into the future.
The age of first maturity of most reef building corals is typically three to eight years (Wallace 1999) and therefore we assume that average age of mature individuals is greater than eight years. Furthermore, based on average sizes and growth rates, we assume that average generation length is 10 years, unless otherwise stated. Total longevity is not known, but likely to be more than ten years. Therefore any population decline rates for the Red List assessment are measured over at least 30 years. See the Supplementary Material for further details on population decline and generation length estimates.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||This species is found in back and fore reef environments, rocky reefs, lagoon habitats, spur and groove formations, channels, and sometimes at the base of the reef, from 2-72 m. Hemispherical heads are more abundant on shallow exposed reefs from 5-20 m (Goreau and Wells, 1967; E. Weil. pers. comm.).|
This species is highly susceptible to white plague and has experienced localized mass mortalities since 1995 in Florida (Richardson et al. 1998). There was no evidence of coral recruitment in the seven years following the epizootic, and D. stokesii populations have continued to decline. The colony size-frequency distribution pattern on these reefs changed over this time period, with the D. stokesii population exhibiting a trend to domination by large colonies, suggesting that the remaining population, while growing, is no longer reproducing (Richardson and Voss, 2005). The species is also susceptible to black band disease, bleaching, high sedimentation, and damage by storms.
In general, the major threat to corals is global climate change, in particular, temperature extremes leading to bleaching and increased susceptibility to disease, increased severity of ENSO events and storms, and ocean acidification.
Coral disease has emerged as a serious threat to coral reefs worldwide and a major cause of reef deterioration (Weil et al. 2006). The numbers of diseases and coral species affected, as well as the distribution of diseases have all increased dramatically within the last decade (Porter et al. 2001, Green and Bruckner 2000, Sutherland et al. 2004, Weil 2004). Coral disease epizootics have resulted in significant losses of coral cover and were implicated in the dramatic decline of acroporids in the Florida Keys (Aronson and Precht 2001, Porter et al. 2001, Patterson et al. 2002). Escalating anthropogenic stressors combined with the threats associated with global climate change of increases in coral disease, frequency and duration of coral bleaching and ocean acidification place coral reefs at high risk of collapse.
Localized threats to corals include fisheries, human development (industry, settlement, tourism, and transportation), changes in native species dynamics (competitors, predators, pathogens and parasites), invasive species (competitors, predators, pathogens and parasites), dynamite fishing, chemical fishing, pollution from agriculture and industry, domestic pollution, sedimentation, and human recreation and tourism activities.
The severity of these combined threats to the global population of each individual species is not known.
In the US, it is present in many MPAs, including Florida Keys National Marine Sanctuary, Biscayne N.P., Dry Tortugas National Park, Buck Island Reef National Monument and Flower Garden Banks National Marine Sanctuary. Also present in Hol Chan Marine Reserve (Belize), Exuma Cays Land and Sea Park (Bahamas). In US waters, it is illegal to harvest corals for commercial purposes. At least in this species, from Florida, a causative agent for white plague has been identified (Richardson et al. 1998), which could have relevance since so little is known of disease etiology. Further taxonomic work is required to clarify the status of both Dichocoenia species. (Aronson, R., Precht, W., Moore, J., Weil, E., and Bruckner, A. pers. comm.)
All corals are listed on CITES Appendix II.
Recommended measures for conserving this species include research in taxonomy, population, abundance and trends, ecology and habitat status, threats and resilience to threats, restoration action; identification, establishment and management of new protected areas; expansion of protected areas; recovery management; and disease, pathogen and parasite management. Artificial propagation and techniques such as cryo-preservation of gametes may become important for conserving coral biodiversity.
|Citation:||Aronson, R., Bruckner, A., Moore, J., Precht, B. & E. Weil. 2008. Dichocoenia stokesii. The IUCN Red List of Threatened Species 2008: e.T133102A3562254.Downloaded on 20 November 2017.|
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