Staghorn corals  (Acropora spp.)

Staghorn 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 (5).

Staghorn corals are considered to be environmentally sensitive corals that require clear, well-circulated water. Unlike other corals, which can obtain nourishment from zooplankton, staghorn corals are almost entirely dependent on the zooxanthellae for food. This means that sunlight is essential, and they are particularly sensitive to any human activities that increase water turbidity, reducing light availability (3).

Two of the three Acropora species in the Atlantic were once very abundant, but in recent decades have remained at low levels of abundance, with no signs of recovery and in some areas, continued decline. These species are believed to be most greatly threatened by disease, temperature-induced bleaching, and physical damage from hurricanes. Threats from anthropogenic physical damage (e.g. vessel groundings, anchors, divers, snorkelers), coastal development, competition and predation are deemed to be moderate. The threat from collection or harvest was deemed abated by effective national and international regulations (3).

Acropora species constituted 13 percent of the global coral trade between 1985 and 1997. Coral is harvested for building materials, curios, jewellery, and for aquariums. Staghorn corals are more common in the dead coral trade, rather than the live aquarium trade (6).

Staghorn corals are listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), and therefore trade in this coral should be carefully regulated, and a permit is required to bring the coral, or objects made from them, into the countries that have signed the CITES convention (1). Staghorn corals will also form part of the marine community in many marine protected areas, or in areas where management plans are in place to protect the coral community. In some areas, coral reefs restoration attempts are being undertaken; in Florida Keys National Marine Sanctuary, efforts have been made to reattach coral fragments, or culture and settle coral larvae. Both activities have had limited success, and new techniques are being pursued (4).