Wrinkle coral  (Coscinaraea crassa)

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

A common, widespread coral of the Indian and Pacific Oceans, the wrinkle coral (Coscinaraea crassa) forms pale brown, plate-like colonies (3). The colonies of the wrinkle coral are composed of numerous tiny, anemone-like animals called polyps. The polyps secrete a hard skeleton, and the skeleton of each individual polyp is known as a ‘corallite’ (3). The corallites of the wrinkle coral are large, compact and arranged in circular rows. The septa have ridge-like extensions, which alternate in height and thickness, but generally protrude beyond each corallite (3) (4).

The wrinkle coral ranges across the southwest and northern Indian Ocean, through the central Indo-Pacific, to Australia, Japan, the East China Sea and the southwest Pacific (1).

The wrinkle coral occurs in shallow reef environments at depths of 10 to 30 metres (1) (3).

The wrinkle coral receives the majority of its nutrition from symbiotic algae, known as zooxanthellae, which live within its tissues. The algae provide the coral with nutrients through photosynthesis, and in return receive a stable environment in which to live. A dependence on photosynthesis restricts corals such as the winkle coral to living in relatively shallow, clear, warm waters, but enables them to grow quickly and form large reef structures (3). The wrinkle coral also feeds actively on tiny zooplankton, which it catches using stinging cells on the tentacles of the polyps (3). 

The wrinkle coral is hermaphroditic, meaning that each polyp contains both male and female sex organs (5). This species releases eggs and sperm into the water for external fertilisation, and the resulting larvae drift in the water column before eventually settling onto the substrate and developing into polyps (3) (6). 

In addition to reproducing sexually, corals are able to reproduce asexually by budding, forming new polyps by the division of existing polyps (3).

With an estimated 20 percent of the world’s coral reefs already destroyed, the wrinkle coral faces many of the threats that are affecting coral reefs globally (7) (8). Worldwide, there is increasing pressure on coastal resources resulting from human population growth and development. There has been a significant increase in domestic and agricultural waste in the oceans, poor land-use practices that result in an increase in sediment running on to the reefs, and over-fishing, which can have knock-on effects on the reef (7). 

However, the major threat to corals is global climate change, with the expected rise in ocean temperatures increasing the risk of coral ‘bleaching’, in which the stressed coral expels its zooxanthellae, often resulting in the death of the coral (8). Climate change may also lead to more frequent, severe storms, which can damage reefs, and rising carbon dioxide levels may make the ocean increasingly acidic. Such stresses can also make corals more susceptible to disease, parasites and predators, such as the crown of thorns starfish (Acanthaster planci) (7) (8) (9).

Parts of the range of the wrinkle coral falls within Marine Protected Areas (1), although enforcement within these can often be poor (9). It also occurs in the Great Barrier Reef, off the coast of Australia, where a range of conservation and research programmes are underway (10). International trade in the winkle coral should be carefully regulated under its listing on Appendix II of the Convention on International Trade in Endangered Species (CITES) (2). 

Recommended conservation measures for the wrinkle coral include research into its populations, abundance, ecology and resilience to threats, as well as monitoring and regulation of its harvest for the aquarium trade (1). It would also benefit from the expansion of Marine Protected Areas, together with further research into coral diseases, and efforts to combat climate change (1) (7) (9).

For further information on the conservation of coral reefs, see:

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