Hard coral  (Favites complanata)

Favites complanata is classified as Near Threatened (NT) on the IUCN Red List (1) and listed on Appendix II of CITES (2).

A widespread but relatively uncommon reef-building species, Favites complanata forms what are known as ‘massive’ colonies, growing in characteristic mound or dome shapes. A colony is composed of numerous individual polyps, which are fleshy and anemone-like when extended. The polyps secrete a hard skeleton called a ‘corallite’, which has thick and slightly angular walls, often varying in shape and colour. Favites complanata is normally brown, although the soft tissue that forms the oral disc between the mouth and the surrounding tentacles is sometimes grey, or green (3).

Favites complanata is found throughout the Indian Ocean, the Red Sea, the Gulf of Aden, the Arabian Gulf, the East China Sea and the West and Central Pacific Oceans (1) (3).

Occurring in shallow-water reef environments, Favites complanata is found down to depths of 30 metres on rocky reefs, reef flats and fringing reefs, as well as in lagoons and on reef slopes (1) (3) (4).

Favites complanata can reproduce asexually, forming colonies by a process called ‘budding’, (where each polyp divides itself into two or more daughter polyps). It is also a hermaphrodite, able to reproduce sexually, producing eggs and sperm that are released into the water during a spawning period (3) (5).

Like other reef-building corals, Favites complanata has many microscopic, photosynthetic algae, called zooxanthellae, living within the polyp tissues. The coral and the algae have a mutually beneficial relationship; the coral provides protection for the algae, which in return provide energy and nutrients through photosynthesis. Both Favites complanata and its zooxanthellae are very sensitive to changes in water temperature and acidity, and any increase in the water temperature greater than one or two degrees above the normal average can stress the coral and cause ‘bleaching’, a phenomenon in which the coral expels it zooxanthellae and turns white (3) (4). Studies of Favites complanata have shown that in this species, bleaching occurs when water temperatures become greater than 30 degrees Celsius (6).

The proportion of corals threatened with extinction has increased dramatically in recent decades, with current estimates suggesting that a third of all coral species have an ‘elevated risk’ of extinction (7). Detailed studies have found that around 20 percent of the world’s coral reefs have already been destroyed, while at least 24 percent of remaining reefs face a high risk of collapse (8).

Threats to Favites complanata include damage caused by fisheries, pollution from agriculture and industry, human developments, recreation and tourism. Favites complanata is also targeted for the aquarium trade. Corals are particularly affected by the changing global climate, with rising sea temperatures, ocean acidification and mass coral bleaching events all contributing to significant declines in corals. In addition, these varying conditions have greatly increased the susceptibility of corals to disease, a factor which has recently emerged as a major cause of reef deterioration (1) (7) (8).

Favites complanata is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), which means that all trade in the species should be carefully monitored. It is also known from several Marine Protected Areas. The identification and establishment of new protected areas may prove crucial for the conservation of Favites complanata and many other corals, while further research into disease, pathogen and parasite management in corals is also needed. Further research into aspects of Favites complanata’s ecology, abundance, population trends, habitat status and taxonomy is required in order to find out more about how the species is likely to respond to the increasing number of threats throughout its range (1).

View information on this species at the UNEP World Conservation Monitoring Centre.

Environment Agency - Abu Dhabi is a principal sponsor of ARKive. EAD is working to protect and conserve the environment as well as promoting sustainable development in the Emirate of Abu Dhabi.

For further information on the conservation of coral reefs see:

• Reef Check:
  http://www.reefcheck.org
• The Coral Reef Alliance:
  http://www.coralreefalliance.org