Stony Corals

The larvae of Stylophora corals readily attach themselves to floating pumice and pieces wood, where they can be transported hundreds or thousands of kilometres. Whilst travelling they can grow into colonies several centimetres across, and are able to produce more larvae en route, thus enabling these corals to be widely distributed (2). Stylophora are hermaphrodites, possessing both male and female reproductive organs. Oddly however, young colonies have been reported to be female only. Eggs are brooded inside the parent polyp until they are fertilised by sperm from another colony, and are then released as free-swimming larvae. The liberation of larvae always occurs after sunset, filling the waters with green, fluorescent larvae that actively swim and may even be capable of swallowing food, before they settle on the substrate to establish a new colony (2).

Stylophora corals are listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), which means that trade in this species should be carefully regulated (1). Indonesia and Fiji have export quotas for Stylophora corals (1). Stylophora corals will form part of the marine community in many marine protected areas (MPAs), which offer coral reefs a degree of protection, and there are many calls from non-governmental organisations for larger MPAs to ensure the persistence of these unique and fascinating ecosystems (4).

These corals were once named as the 'tramp' species of the coral world, due to their tendency to attach themselves to floating objects on which they travel hundreds of kilometres, reproducing on the way (2). These corals form colonies that are generally branching, with short branches. Colonies are composed of many individual coral polyps, each bearing tentacles that are only extended at night (3). Stylophora corals are most commonly cream and pink, but species may also be red, yellow, tan and occasionally green (2).

Occurs in a variety of reef environments, from shallow reef flats exposed to strong wave action, to protected lagoons and lower reef slopes (3).

Stylophora occurs in the Indo-Pacific, ranging from the Red Sea to the central Pacific (3).

Listed on Appendix II of CITES (1).

Stylophora corals face the many threats that are impacting coral reefs globally. It is estimated that 20 percent of the world's coral reefs have already been effectively destroyed and show no immediate prospects of recovery, and 24 percent of the world's reefs are under imminent risk of collapse due to human pressures. These human impacts include poor land management practices that are releasing more sediment, nutrients and pollutants into the oceans and stressing the fragile reef ecosystem. Over fishing has 'knock-on' effects that results in the increase of macro-algae that can out-compete and smother corals, and fishing using destructive methods physically devastates the reef. A further potential threat is the increase of coral bleaching events, as a result of global climate change (4). Stylophora corals may also be threatened by harvesting for the coral trade. Stylophora is generally traded dead, for ornaments and jewellery, rather than alive, for the aquarium industry (5).