|Scientific Name:||Pavona varians|
|Species Authority:||Verrill 1864|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Hoeksema, B., Rogers, A. & Quibilan, M.|
|Reviewer/s:||Livingstone, S., Polidoro, B. & Smith, J. (Global Marine Species Assessment)|
The most important known threat for this species is extensive reduction of coral reef habitat due to a combination of threats. Specific population trends are unknown but population reduction can be inferred from estimated habitat loss (Wilkinson 2004). It is widespread and common throughout its range and therefore is likely to be more resilient to habitat loss and reef degradation because of an assumed large effective population size that is highly connected and/or stable with enhanced genetic variability. Therefore, the estimated habitat loss of 20% from reefs already destroyed within its range is the best inference of population reduction since it may survive in coral reefs already at the critical stage of degradation (Wilkinson 2004). This inference of population reduction over three generation lengths (30 years) does not meet the threshold of a threat category and this species is Least Concern. However, because of predicted threats from climate change and ocean acidification it will be important to reassess this species in 10 years or sooner, particularly if the species is also observed to disappear from reefs currently at the critical stage of reef degradation.
|Range Description:||In the Indo-West Pacific, this species is found in the Red Sea and the Gulf of Aden, the Southwest and Northwest Indian Ocean, the Arabian/Iranian Gulf, the Central Indian Ocean, the Central Indo-Pacific, Tropical Australia, Southern Japan and the South China Sea, the Oceanic West Pacific, the Central Pacific, the Hawaiian Islands and Johnston Atoll, and the Far Eastern Pacific.
Widespread distribution within the Eastern Tropical Pacific region: Mexico: Jaltemba Island to Punta Mita, and from Isabel Island to Marias Islands (Nayarit); Revillagigedo Islands; Zihuatanejo to Acapulco (Guerrero); and Puerto Escondido to Huatulco (Oaxaca) (Reyes-Bonilla et al. 2005, Calderon-Aguilar 2005, Reyes-Bonilla 2003); Costa Rica: Guanacaste, Bahía Culebra, Punta Mala, Manuel Antonio, Peninsula de Osa, Golfo Dulce, Caño Island, and Cocos Island (Guzman and Cortes 1992, Cortés and Guzmán 1998); Panama: throughout the Gulfs of Chiriqui and Panama (Glynn 1997, Guzmán et al. 2004, Maté 2003a,b); Colombia (Glynn and Ault 2000, Reyes 2000, Zapata and Vargas-Ángel 2003): Ensenada de Utría, Tebada; Gorgona Island and Malpelo Island; Ecuador: Salango Island, Los Frailes, Sucre Island and La Plata Island, and throughout the Galápagos Archipelago (except for Fernandina and the west side of Isabela) (Glynn et al. 2001, Glynn 2003).
Native:American Samoa (American Samoa); Australia; Bahrain; British Indian Ocean Territory; Cambodia; Christmas Island; Cocos (Keeling) Islands; Colombia; Comoros; Cook Islands; Costa Rica; Djibouti; Ecuador; Egypt; El Salvador; Eritrea; Fiji; French Polynesia; Guadeloupe; Honduras; India; Indonesia; Iran, Islamic Republic of; Iraq; Israel; Japan; Jordan; Kenya; Kiribati; Kuwait; Madagascar; Malaysia; Maldives; Marshall Islands; Mauritius; Mayotte; Mexico; Micronesia, Federated States of; Mozambique; Myanmar; Nauru; New Caledonia; Nicaragua; Niue; Northern Mariana Islands; Oman; Pakistan; Palau; Panama; Papua New Guinea; Philippines; Qatar; 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 Arab Emirates; United States Minor Outlying Islands; Vanuatu; Viet Nam; Wallis and Futuna; Yemen
|FAO Marine Fishing Areas:||
Indian Ocean – eastern; Indian Ocean – western; Pacific – eastern central; Pacific – northwest; Pacific – southeast; Pacific – southwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
This is a common species.
In the Eastern Tropical Pacific region the relative abundance of Pavona varians is as follows:
Considered abundant at Clipperton Atoll (Glynn et al. 1996, Glynn and Ault 2000). According to Glynn et al. (1996), P. varians is dominant on the lower reef slopes, where it often covers more than 90% of the substratum. In addition, the lower zone limit of this species is unknown; colony abundance at some sites shows no signs of decreasing at 80 m depth (Glynn et al. 1996).
According to Maté (2003b), the relative abundance of P. varians in the Gulf of Panama, varies from abundant to rare depending on site; and common to rare in the Gulf of Chiriquí. However, Guzman (pers. comm.) disagrees with Maté (2003b), since Guzmán et al. (in prep.) recorded P. varians at 136 sites in the Gulf of Chiriquí and at 61 sites at las Perlas Archipelago. At Coiba Archipelago, Gulf of Chiriquí, P. varians was present in 75 to 100% of the sites studied by Guzmán et al. (2004).
P. varians was considered abundant at Caño Island, Costa Rica (Guzmán and Cortés 2001); common along mainland Colombia (Ensenada de Utría and Tebada), as well as in Cocos Island, Costa Rica (Glynn and Ault 2000, Guzman and Cortes 2006) and Malpelo Island, Colombia (Edgar pers. comm.). Uncommon in mainland Costa Rica and the Galápagos Island, Ecuador (Glynn and Ault 2000, Glynn 2003). Rare in Mexico (from Nayarit to Oaxaca and the Revillagigedo Islands) and mainland Ecuador (Reyes-Bonilla 2003, Glynn 2003).
According to Glynn et al. (2000), population densities increased from ~1-4 colonies per 20 m² immediately following the 1982-83 ENSO to six to 12 colonies at Caño Island (Costa Rica) and Uva Island (Panama) after 10-yr. Survivorship to reproductive maturity at Caño Island, Uva Island and the southern Galapagos corresponded with recruitment rates of 0.1, 0.2 and 0 colonies/m², respectively, and recovered to pre-ENSO abundances at these sites (Glynn et al. 2000). Recruitment success of P. varians at Uva Island was significantly related to maximum monthly positive sea surface temperature (SST) anomalies that occurred in the year preceding recruitment over the period 1982 to 1996; recruitment failed when SST anomalies exceeded 1.6 to 1.9°C during the severe ENSO events of 1982-83 and 1997-98 (Glynn et al. 2000).
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. Follow the link below for further details on population decline and generation length estimates.
|Habitat and Ecology:||
This species occurs in most reef environments. It occurs on shallow and deeper reefer slopes and on vertical walls. Generally, Pavona varians occurs broadly amongst coral reefs and coral communities on rocks and rubble substrata, but is absent from shallow platforms with high energy (Cortés and Guzmán 1998, Glynn et al. 2000); in some locations this coral is found in cryptic habitats (Glynn et al. 2000). The maximum size is over 1 m. This species is typically found from 2-40 m but has been reported from 80 m.
P. varians is a broadcast-spawner, releasing masses of minute eggs and sperm (Glynn et al. 2000). Most colonies utilize an alternating periodic sequential hermaphrodite mode of reproduction (Glynn et al. 2000). Glynn et al. (2000) suggest year-round reproductive activity. In addition, spawning appears to increase during high temperature conditions (Glynn et al. 2000). According to Glynn et al. (2000), P. varians may reach reproductive maturity at seven years; while the minimum colony size at first reproduction was found to be 5 cm (about five years old). The growth rate of P. varians has been estimated as 0.35 cm/yr in Costa Rica (Guzman and Cortes 1993). Recruitment of P. varians has been described as nil to low and patchy (Glynn et al. 2000).
The total number of corals (live and raw) exported for this species in 2005 was 223.
El Niño Southern Oscillation (ENSO) events are the most important source of natural disturbance controlling coral communities (Glynn 1990). Pavona species have a high sensitivity to extreme elevated temperatures that interfere with reproduction and recruitment (Glynn et al. 2000). El Niño disturbance could have perilous consequences for small populations of eastern Pacific reef corals (Glynn 1988).
Bryant et al. (1998), based on four anthropogenic factors (coastal development; overexploitation and destructive fishing practice; inland pollution and erosion, and marine pollution), estimated a high threat to coral reefs in the coast of Costa Rica, Panama and Colombia. High levels of siltation caused by accelerated coastal erosion have degraded coral reefs in Costa Rica, Colombia and Ecuador (Glynn 2001).
Other threats (Glynn et al. 2000): small colony size; slow skeletal growth; susceptibility to Acanthaster planci predation, and infrequent asexual fragmentation. Crown-of-thorns starfish (COTS) (Acanthaster planci) are found throughout the Pacific and Indian Oceans, and the Red Sea. These starfish are voracious predators of reef-building corals, with a preference for branching and tabular corals such as Acropora species. Populations of the crown-of-thorns starfish have greatly increased since the 1970s and have been known to wipe out large areas of coral reef habitat. Increased breakouts of COTS has become a major threat to some species, and have contributed to the overall decline and reef destruction in the Indo-Pacific region. The effects of such an outbreak include the reduction of abundance and surface cover of living coral, reduction of species diversity and composition, and overall reduction in habitat area.
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. Pavona varians. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 23 May 2013.|
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