Taxonomic Notes
According to the
WoRMS online database (accessed January 2023), it is taxon inquirendum (the taxonomic validity of this species is uncertain or disputed by different experts). It is considered valid according to Veron
et al. (2016) but it was not included in the taxonomic revision of
Acropora species by Wallace
et al. (2012).
Justification
There is high taxonomic uncertainty associated with this species. Little is known on its distribution, population, ecology and potential threats; therefore, it is listed as Data Deficient.
Geographic Range Information
If valid, this species occurs in the southern Red Sea, the Gulf of Aden, and the southwest Indian Ocean (Veron et al. 2016). Reports from West Malaysia and Brunei (Huang et al. 2015) and the Sulu Sea (DeVantier and Turak 2017) may require verification.
The depth range is 1–15 m.
Population Information
This species is common (DeVantier and Turak 2017).
Habitat and Ecology Information
This species occurs on shallow rocky foreshores and reefs. It has a preference for clear water, and can tolerate a broad range of wave exposure.
The age at first maturity of most Acropora species is typically 4 years; however, it can vary between 3 and 8 years (Harrison and Wallace 1990, Iwao et al. 2010, Baria et al. 2012, Montoya-Maya et al. 2014, Ligson and Cabaitan 2021). Based on average sizes and growth rates, we also infer that the average length of one generation is 10 years. Longevity is not known, but is likely to be greater than 10 years. Therefore, any population decline rates estimated for the purposes of this Red List assessment are measured over a time period of 30 years.
Threats Information
Members of this genus have a low resistance and low tolerance to bleaching and disease, and are slow to recover. 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 (El Niño/La Niña Southern Oscillation) events and storms, and ocean acidification (Richards et al. 2008). The most recent, and first, multi-year, global bleaching event (spanning hundreds of kilometers or more) was from 2014 to 2017. Nearly 30% of reefs suffered mortality level stress, more than 50% of affected reef areas were impacted at least twice, and some localities saw almost complete coral cover loss (Blunden et al. 2018, Vargas-Angel et al. 2019, Eakin et al. 2019). The average interval between bleaching events is now more than 50% less than before, preventing full reef recovery (Hughes et al. 2018).
This Acropora growth form is moderately susceptible to predation by crown-of-thorns starfish (COTS) (Acanthaster planci), which 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 consume large areas of coral reef. 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.
Coral disease has emerged as a serious threat to coral reefs worldwide and a major cause of reef deterioration, and may be as likely to cause mortality as bleaching in the coming decades (Weil et al. 2006, Richards et al. 2008, Maynard et al. 2015). 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). As noted in Walton et al. (2018), in addition to thermal stress, increased coral disease prevalence and mortality can be linked to reduced water quality (Bruno et al. 2003) and clarity (van Woesik and McCaffrey 2017), nutrient enrichment (Vega Thurber et al. 2013), dredging associated sedimentation (Pollock et al. 2014, Miller et al. 2016), and plastic pollution. Based on a survey of 159 reefs in the Asia-Pacific region, the likelihood of disease increased 20-fold when corals are in contact with plastic (Lamb et al. 2018).
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 et al. 2006). Increased coral disease levels on the GBR were correlated with increased ocean temperatures (Boyett 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 (Richards et al. 2008); however, more than 60% of the world’s reefs are immediately threatened by local pressures (Bridge et al. 2013).
Use and Trade Information
Conservation Actions Information
All stony corals are listed on CITES Appendix II. All stony corals (Scleractinia) fall under Annex B of the European Union Wildlife Trade Regulations (EU 2019), and have done so since 1997. Furthermore, several countries (India, Israel, Somalia, Djibouti, Solomon Islands and the Philippines) at various stages have banned either the trade or export of CITES II listed species, which includes all stony corals, since 1999 (UNEP 2020). Fiji, Indonesia and Malaysia currently (2020) have quotas for the number of wild Acropora species in general for export, which range from 3,000 to 377,500 pieces per annum depending on the country (UNEP-WCMC 2020).
Taxonomic research is needed.