Red coral (Corallium rubrum)
|Also known as:||angel skin coral, midway coral, noble coral, precious coral, Sardinia coral|
Corallium rubrum is listed on Annex V of the European Union Habitats Directive (2). This genus is not listed in the CITES convention.
The beauty of Corallium corals may be their downfall, as they are harvested at unsustainable levels to be made into expensive jewellery or desirable art objects. Each coral colony is formed from thousands of individual, but genetically identical, coral polyps; basically anemone-like animals that secrete a skeleton. White, transparent Corallium polyps, each bearing eight tentacles, form tall, branching, tree-like colonies. These can attain heights from 50 centimetres to over one meter, and range in colour from pure white to shades of pink, salmon, blood-red and orange (1).
Occurs in the Mediterranean Sea and eastern Atlantic Ocean, at depths of 7 to 300 metres (1).
Corallium corals inhabit deep water, rocky bottom habitats and typically aggregate on banks, seamounts, under ledges, and in and around caves; generally where there are strong bottom currents (1).
Corallium corals have separate male and female colonies (not all corals do), and from the few reports of reproduction, it is believed that fertilization is internal, and therefore depends on free-swimming sperm from male colonies reaching the polyps of female colonies. The fertilised egg then develops into larvae within the female polyp’s body cavity. Development takes about 30 days, and the larvae are subsequently released into the water column between late July and August. The larvae quickly settle on the substrate close to the parent colony, where they attach themselves and form a new colony (3). Corallium colonies grow at a slow rate of less than one centimetre a year, do not reach maturity until between 7 and 12 years old, and can live for up to 100 years (1).
Unlike many coral species, Corallium corals do not have the symbiotic algae zooxanthellae living within the coral tissue; they are azooxanthellate (1). Lacking zooxanthellae means that the coral must obtain nutrients by another method. Corallium corals feed on particles of organic matter, suspended in the water, which are captured by their tentacles. They also occasionally capture and consume larger zooplankton (1).
Corallium corals have been harvested for over 5,000 years; in the past, it was believed by some that Corallium held magical powers such as overcoming evil and protecting crops, and it was used as an antidote for poison and for treating other ailments. Today, millions of items are traded internationally as jewellery and art objects, and overexploitation poses the greatest threat to this beautiful coral (1). Global harvest statistics show a pattern of new stocks being discovered and rapidly exhausted. From 1950 to 2001, the abundance of Mediterranean and Pacific species rapidly declined, following overexploitation (1). The harvest of Corallium rubrum in the Mediterranean has declined by 66 percent between 1986 and 2001 (4), and most western Pacific populations of Corallium have been depleted within four to five years of their discovery (1). Corallium corals possess life-history characteristics that make them particularly vulnerable to overexploitation, including extreme longevity, a slow growth rate, late age of maturity and low fecundity (1).
Corallium corals are also likely to be threatened by human activities that are impacting coral populations worldwide. This includes pollution, sedimentation, recreational diving, and habitat degradation associated with longline fishing and bottom trawling (1). In addition, Corallium corals may be threatened by global warming. In 1999, a mass mortality event of Corallium corals occurred off the coastline of the Provence region of France. The exact cause of this die-off was unknown, but was thought to be linked to a period of high temperatures that the region experienced. This could have caused physiological stress to the corals, or triggered the development of pathogenic agents that otherwise would have remained non-virulent (5). Mass mortality events such as this are likely to become more frequent as the global warming trend continues.
Whilst there are no international measures in place to protect Corallium species, there are a number of national measures in place. Corallium rubrum is listed in Annex V of the European Union Habitats Directive (2), and in 1994 the European Union banned the use of dredging equipment for the harvest of Corallium in the Mediterranean (1). In the United States, the Western Pacific Fishery Management Council’s Precious Corals Fisheries Management Plan has regulated the harvest of Corallium species since 1983.
The plan imposes permit requirements valid for specific locations, harvest quotas for precious coral beds, a minimum size limit for pink coral, gear restrictions, area restrictions, and fishing seasons (1).
A listing on the Convention on International Trade in Endangered Species (CITES), which regulates international trade in threatened species, would help safeguard these incredible animals. In June 2007, Corallium corals came close to receiving this protection in a CITES conference, but the initial decision to list the coral was overturned at the last moment by a secret ballot, following a massive lobbying effort by the coral industry and some exporting countries (6). Sadly, this leaves the red coral unprotected, and vulnerable to the devastating impacts of a relentless trade.
For further information on the conservation of red and pink corals see SeaWeb’s Too Precious To Wear campaign:
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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.
- Fecundity: a measure of fertility, such as sperm count or egg count or the number of live offspring produced by an organism.
- Larvae: relating to corals: the stages of development before settlement on the reef. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
- Polyp: 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.
CITES. (2007) Consideration of Proposals for Amendment of Appendices I and II, Proposal 21. Fourteenth Meeting of the Conference of the Parties, The Hague. Available at:
European Union Habitats Directive (August, 2007)
- Santangelo, G., Carletti, E., Maggi, E. and Bramanti, L. (2003) Reproduction and population sexual structure of the overexploited Mediterranean red coral Corallium rubrum. Marine Ecology Progress Series, 248: 99 - 108.
- Santangelo, G. and Abbiati, M. (2001) Red coral: conservation and management of an over-exploited Mediterranean species. Aquatic Conservation: Marine and Freshwater Ecosystems, 11: 253 - 259.
- Garrabou, J., Perez, T., Sartoretto, S. and Harmelin, J.G. (2001) Mass mortality event in red coral Corallium rubrum populations in the Provence region (France, NW Mediterranean). Marine Ecology Progress Series, 217: 263 - 272.
SeaWeb (August, 2007)