|Scientific Name:||Galaxea astreata (Lamarck, 1816)|
|Red List Category & Criteria:||Vulnerable A4cd ver 3.1|
|Assessor(s):||Hoeksema, B., Rogers, A. & Quibilan, M.|
|Reviewer(s):||Livingstone, S., Polidoro, B. & Smith, J. (Global Marine Species Assessment)|
This species is widespread and common throughout its range. However, it is particularly susceptible to bleaching and extensive reduction of coral reef habitat due to a combination of threats, and is harvested by the aquarium trade. 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 35% over three generation lengths (30 years) is the best inference of population reduction and meets the threshold for Vulnerable under Criterion A4c,d. It will be important to reassess this species in 10 years time because of predicted threats from climate change and ocean acidification.
|Range Description:||In the Indo-West Pacific, this species is found in the Red Sea and Gulf of Aden, southwestern Indian Ocean, central Indian Ocean, central Indo-Pacific, northern, western and eastern Australia, Japan and South China Sea, oceanic West Pacific.|
Native:American Samoa; Australia; British Indian Ocean Territory; Cambodia; China; Comoros; Djibouti; Egypt; Eritrea; Fiji; India; Indonesia; Israel; Japan; Jordan; Kenya; Kiribati; Madagascar; Malaysia; Maldives; Marshall Islands; Mauritius; Mayotte; Micronesia, Federated States of ; Mozambique; Myanmar; Nauru; New Caledonia; Pakistan; Palau; Papua New Guinea; Philippines; Réunion; Samoa; Saudi Arabia; Seychelles; Singapore; Solomon Islands; Somalia; Sri Lanka; Sudan; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Tokelau; Tonga; Tuvalu; United States Minor Outlying Islands; Vanuatu; Viet Nam; Wallis and Futuna; Yemen
|FAO Marine Fishing Areas:|
Indian Ocean – western; Indian Ocean – eastern; Pacific – eastern central; Pacific – northwest; Pacific – southwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species is common.|
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 more resilient to some of the threats faced by corals and therefore population decline is estimated using the percentage of destroyed reefs only (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 of 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:||Unknown|
|Habitat and Ecology:||This species is found in reef environments protected from strong wave action. Sparse colonies of G. astreata are found from 3-15 m in the South China Sea and Gulf of Siam (Titlyanov and Titlyanova 2002). This species is considered to be a main reef-framework builder and is found at 20-30 m on the Chagos lagoon (Sheppard 1982). The maximum size is over 2 m.|
|Generation Length (years):||8|
This species exhibited high bleaching and mortality in the 1998 bleaching event in Palau. It was affected in all areas and was one of the most affected species (Brunno et al. 2001).
This species is targeted for the aquarium trade. Indonesia is the largest exporter with an annual quota of 4,650 live pieces in 2005. Fiji had an export quota of 606 pieces in 2005. The total number of corals (live and raw) exported for this species in 2005 was 5,529.
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). In the Indo-Pacific, disease is also on the rise with disease outbreaks recently reported from the Great Barrier Reef (Willis et al. 2004), Marshall Islands (Jacobson 2006) and the northwestern Hawaiian Islands (Aeby 2006). Increased coral disease levels on the GBR were correlated with increased ocean temperatures (Willis et al. 2007) supporting the prediction that disease levels will be increasing with higher sea surface temperatures. 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 in the Indo-Pacific 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.
All corals are listed on CITES Appendix II. Parts of the species’ range fall within Marine Protected Areas.
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.
Having timely access to national-level trade data for CITES analysis reports would be valuable for monitoring trends this species. The species is targeted by collectors for the aquarium trade and fisheries management is required for the species, e.g., MPAs, quotas, size limits, etc. Consideration of the suitability of species for aquaria should also be included as part of fisheries management, and population surveys should be carried out to monitor the effects of harvesting. Recommended conservation measures include population surveys to monitor the effects of collecting for the aquarium trade, especially in Indonesia.
|Citation:||Hoeksema, B., Rogers, A. & Quibilan, M. 2008. Galaxea astreata. The IUCN Red List of Threatened Species 2008: e.T133354A3704161.Downloaded on 21 August 2018.|
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