Acanthaster planci is the principle natural enemy of reef-building corals. (Credit: © IRD / E. Folcher)

Feb. 1, 2013 — Acanthaster planci is the principle natural enemy of reef-building corals. Outbreaks of this coral-feeding starfish occur periodically, due to reasons that remain unclear. It decimates entire reefs in the space of just a few years, as has been the case in French Polynesia since 2004. A new study conducted by IRD researchers and their partners(1) describes this population explosion around Moorea, the “sister island of Tahiti”(2). The rate of living coral cover in ocean depths and lagoons alike has dropped from 50% (healthy reef) to under 5% in 2009. The ecosystem will need at least a decade to be restored to its original state.

The crown-of-thorns starfish (Acanthaster planci) is the greatest natural threat to coral populations. Outbreaks of the species occur periodically in the Indo-Pacific ocean and lead to the devastation of entire reefs, as IRD researchers and their partners(1) observed in French Polynesia.

The starfish has spread from island to island

The archipelago has been suffering from a new population explosion of the predatory starfish since 2004. It is one of the most intense and devastating outbreaks ever recorded. The outbreak ofAcanthaster began in a very specific location in the Austral and Leeward Islands, then in 2006, the starfish colony spread to Tahiti and Moorea(2). Thanks to a dozen stations around the island of Moorea, scientists were able to make spatio-temporal observations of the dynamics of the infestation of coral populations. Thus, in a new study published in PLoS One, they described the spread of the coral reef invasion.

Ocean depths and lagoons alike

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