Lithophyllon coral  (Lithophyllon undulatum)

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

A colourful coral of the Indian and Pacific Oceans, Lithophyllon undulatum initially forms encrusting colonies, but as it increases in size it grows in flat, leaf-like plates with lobed margins (3) (4). The colonies of Lithophyllon undulatum 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). Within the corallites of each polyp of Lithophyllon undulatum, the septa radiate from the centre in an alternating pattern and become longer and thinner near the periphery (4). Prominent grooves also run across the colony surface (3). 

Lithophyllon undulatum is variable in colour, usually being deep green or brown in the northern part of its range, but often dark blue with white corallite centres in the south (3).

Occurring in the eastern Indian Ocean and western Pacific Ocean, Lithophyllon undulatum ranges from Indonesia and Papua New Guinea, north to Japan and the East China Sea, south to Australia, and east to Samoa and Palau (1).

Lithophyllon undulatum is usually found growing on hard substrate or rocky walls of reef slopes, between depths of 1 and 20 metres (1) (4).

Lithophyllon undulatum 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 Lithophyllon undulatum to living in relatively shallow, clear, warm waters, but enables them to grow quickly and form large reef structures. Lithophyllon undulatum also feeds actively on tiny zooplankton, which it catches using stinging cells on the tentacles of the polyps (3).

With an estimated 20 percent of the world’s coral reefs already destroyed, Lithophyllon undulatum 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 Lithophyllon undulatum fall 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 mushroom 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 Lithophyllon undulatum 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) (8) (9).

Find out more about the conservation of coral reefs:

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