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Starfish really a gang of four

10.12.2008

The crown-of-thorns starfish, a notorious threat to coral reefs, comprises four species and not one. An international team of researchers, led by Catherine Vogler and Prof. Gert Wörheide from the GeoBioCenterLMU, published this surprise finding in the international journal "Biology Letters". They point out that this discovery could have important consequences for coral reef conservation.

The crown-of-thorns starfish Acanthaster planci (COTS) is infamous throughout the Indian and Pacific oceans for its population outbreaks that destroy coral reefs. This predator, covered in poisonous spines, feeds by wrapping its stomach around coral and digesting it on the spot, leaving only the white skeleton behind. An important element of the ecosystem in normal densities, it can destroy entire reefs when outbreaking. Because coral reefs are already subjected to many other pressures – such as global warming, land reclamation, pollution, overfishing – outbreaks can have dramatic ecological and economic consequences, impacting the environment, livelihoods and tourism. But even though COTS have been intensively researched for the last decades, the causes of outbreaks are still poorly understood.

To complicate the issue, the COTS phenomenon has just reached a new level: an international team of researchers from the USA, Panama and Germany has discovered that COTS are not a single widespread species, but instead four distinct species. Using a genetic approach, they show that these species are located in the Pacific, the Red Sea, the Northern and the Southern Indian Ocean. This discovery could be very important for coral reef conservation. Until now, all research and management strategies have come from the Pacific, because COTS are a serious threat to the Great Barrier Reef. But this could mean we are not dealing with the other three species adequately. The different species could favour different habitats, and have different reproductive and nutritional requirements, and this in turn could dictate when and where outbreaks occur. Future research will be necessary to determine whether the four species need to be managed in a different way to minimise the impact of catastrophic outbreaks in different regions of the world.

These findings were published in the December 2008 issue of the Royal Society’s journal "Biology Letters".

Vogler C., Benzie J., Lessios H., Barber P., Wörheide G. (2008) A threat to coral reefs multiplied? Four species of crown-of-thorns starfish. Biology Letters 4, 696–699.