Porites 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). The predatory starfish, Acanthaster planci, or ‘crown-of-thorns starfish’, feeds on a wide range of coral species. For little understood reasons, outbreaks of this starfish occur at regular intervals, and large numbers of starfish can have devastating effects on the reef. They can eat so much that they can kill most of the living coral in a region, which may take the reef up to fifteen years to fully recover (5). Due to the exceptionally slow growth rate of Porites corals, these species may not be able to fully recover in the time before the next starfish outbreak, and thus may be sent into a period of prolonged decline (6).
An additional potential threat arises from collection for the coral trade. Porites is one of four genera that constitute the majority of the dead coral trade, for ornaments and jewellery. Live Porites are also collected at a lower level for the aquarium industry, and has previously been traded for biomedical purposes. This trade, which probably supplied a specialised market for the use of coral in bone grafts, peaked in 1992 but has since declined to extremely low levels (7).