Pagoda coral  (Turbinaria mesenterina)

The pagoda coral is classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix II of CITES (2).

Turbinaria mesenterina is a reef-building coral, its colonies forming thin, overlapping, grey-green or grey-brown plates (3) (4) (5). The plates may be variable in shape, depending on water depth and hence light availability, with those in shallow areas highly contorted and fused, those on upper reef slopes more upright and tiered, and those in deep water usually horizontal (3) (4) (6) (7). The colonies of this species are usually less than a metre across, but may grow much larger on fringing reefs (3) (4). As in other corals, the colonies are made up of numerous tiny polyps, which secrete a calcium carbonate skeleton. The individual polyp skeletons of this species, known as ‘corallites’, are around 2.5 millimetres in diameter, and are crowded together (3) (4). Each polyp bears relatively long tentacles, which are usually only extended at night (3) (4) (8).

Turbinaria mesenterina is similar in appearance to Turbinaria reniformis, but can be recognised by its slightly different colour, more horizontal than vertical fronds, and smoother appearance (3) (4). Turbinaria peltata also occurs in similar conditions to this species, but can be distinguished by its thicker plates and larger polyps, whose tentacles are often extended during the day (5).

Turbinaria mesenterina occurs across the Indian Ocean, Red Sea, Gulf of Aden, Arabian Gulf, and the western and central Pacific Ocean (1) (3) (4) (8).

This coral is common in shallow, turbid reef habitats, where it may be a dominant species (1) (3) (4) (5). Turbinaria mesenterina has been recorded at depths of up to 20 metres (1).

Turbinaria is one of just four hermatypic (reef-building) coral genera within the Dendrophylliidae family (3). Like other hermatypic corals, Turbinaria mesenterina obtains most of its nutrients from microscopic algae, known as zooxanthellae, which live within its tissues and produce energy-rich nutrients through photosynthesis. The diet may also be supplemented with zooplankton, caught using stinging cells on the tentacles (3) (9).

In general, the greatest threat to coral species is believed to be global climate change, which is likely to lead to an increase in severe storms, and to increased ocean acidification, which can reduce the ability of a coral to produce its hard skeleton. Rising sea temperatures can also lead to coral bleaching, in which the coral expels it zooxanthellae, often resulting in death. In addition, coral reefs are under pressure from a range of localised threats including human development, destructive fishing practices, pollution, sedimentation, disease and invasive species (1) (9) (10) (11).

Although still widespread and common throughout its range (1), Turbinaria mesenterina is likely to face similar threats to other reef-building corals, around a third of which are now threatened with extinction (10). In addition, this species is collected for the aquarium trade (1), and has recently been affected by an infectious disease known as Australian subtropical white syndrome in waters around Australia (12). However, it has been shown to be relatively tolerant of sedimentation, suggesting that increased sedimentation, associated with erosion and increased storm activity, is less likely to pose a threat than in many other coral species (13).

Although parts of this species’ range fall within Marine Protected Areas (1), including the Great Barrier Reef, off the coast of Australia (14), many of these areas do not receive adequate enforcement (9), and currently less than half a percent of all marine habitats are protected (15). International trade in Turbinaria mesenterina should be regulated by its listing on Appendix II of the Convention on International Trade in Endangered Species (CITES) (2).

Conservation measures recommended for corals include further research, expansion of Marine Protected Areas, disease and parasite management, artificial propagation techniques, and fisheries management (1) (9) (11). It will also be important to monitor the effect of collection of Turbinaria mesenterina for the aquarium trade, particularly in Indonesia, the largest exporter (1), while mechanical removal of diseased colony margins may provide a method for minimising the effects of disease on the species, albeit on a fairly local scale (12).

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

For more information on corals and their conservation see:

• Veron, J.E.N. (2000) Corals of the World. Australian Institute of Marine Science, Townsville, Australia.
• Reef Check
  http://www.reefcheck.org/
• The Coral Reef Alliance
  http://www.coral.org/