Yellow scroll coral (Turbinaria reniformis)
Classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix II of CITES (2).
Turbinaria reniformis is a reef-building coral that forms colonies of mostly horizontal, overlapping plates that can grow over one metre in diameter. Each colony is comprised of numerous widely spaced polyps. The overall colour of Turbinaria reniformis is usually yellow-green (3).
Turbinaria reniformis is distributed widely in shallow waters of the Indian Ocean (including the Red Sea and the Arabian Gulf) and the western Pacific (1).
Found at depths of 2 to 15 metres, sometimes forming large stands in turbid water on fringing reefs (1) (3).
Unlike most corals within the family Dendrophyllidae, Turbinaria reniformis is zooxanthellate. Zooxanthellate corals live in symbiosis with unicellular algae known as zooxanthellae, which are essential to their growth and survival. Protected within the coral tissue, the algae provide their hosts with nutrients and energy, whilst also helping to remove metabolic wastes. The cost of this symbiosis is that zooxanthellate corals are constrained to live in relatively shallow waters where the algae are able to photosynthesise (3).
All Turbinaria species breed during the autumn in falling sea temperatures. Unlike most corals which are hermaphroditic (3), Turbinaria have separate male and female sexes, and probably release gametes for external fertilisation (4).
Around one third of the world’s reef building corals are threatened with extinction (5). The principal threat to corals is the rise in sea temperature associated with global climate change. This leads to coral bleaching, where the symbiotic algae are expelled, leaving the corals weak and vulnerable to an increasing variety of harmful diseases. Climate change is also expected to increase ocean acidification and result in a greater frequency of extreme weather events such as destructive storms. This is not to mention the localised threats to coral reefs from pollution, destructive fishing practices, invasive species, human development, and other activities (1) (5).
Although Turbinaria reniformis is still relatively widespread and common in parts of its range, evidence of an overall global decline in coral habitat is an indication that this species is almost certainly declining (1).
In addition to being listed on Appendix II of CITES, which makes it an offence to trade Turbinaria reniformis without a permit, this coral falls within several Marine Protected Areas across its range. To specifically conserve Turbinaria reniformis, recommendations have been made for a raft of studies into various aspects of its taxonomy, biology and ecology, including an assessment of threats and potential recovery techniques (1).
For further information on the conservation of coral reefs see:
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- Colony: Relating to corals: corals composed of numerous genetically identical individuals (also referred to as zooids or polyps), which are produced by budding and remain physiologically connected.
- Fertilisation: the fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
- Gametes: reproductive cells which carry the genetic information from their parent, and are capable of fusing with gametes of the opposite sex to produce a fertilized egg. In animals, male gametes are called sperm and female gametes are called ova.
- Hermaphroditic: possessing both male and female sex organs.
- Photosynthesise: Metabolic process characteristic of plants in which carbon dioxide is broken down, using energy from sunlight absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product.
- Polyps: Typically sedentary soft-bodied component of Cnidaria (corals, sea pens etc), which comprise of a trunk that is fixed at the base; the mouth is placed at the opposite end of the trunk, and is surrounded by tentacles.
- Symbiosis: relationship in which two organisms form a close association, the term is now usually used only for associations that benefit both organisms (a mutualism).
IUCN Red List (March, 2009)
CITES (March, 2009)
- Veron, J.E.N. (2000) Corals of the World. Australian Institute of Marine Science, Townsville, Australia.
- Veron, J.E.N. (1993) Corals of Australia and the Indo-Pacific. University of Hawaii Press, Honolulu.
- Carpenter, KE et al. (2008) One-Third of Reef-Building Corals Face Elevated Extinction Risk from Climate Change and Local Impacts. Science, 321: 560 - 563.