Fishing Ban Guards Coral Reefs Against Predatory Starfish Outbreaks
No-take marine reserves where fishing is banned can have benefits that extend beyond the exploited fishes they are specifically designed to protect, according to new evidence from Australia's Great Barrier Reef reported in the July 22nd issue of Current Biology. Researchers have found that outbreaks of large, predatory crown-of-thorns starfish (Acanthaster planci), which can devastate coral reefs, occur less often in protected zones, although they don't yet know exactly why.
The geographic range of A. planci includes the most biodiverse as well as some of the most threatened reefs on earth," said Hugh Sweatman of the Australian Institute of Marine Science. "This study provides an additional argument for establishment of effective marine protected areas across the range, as refuges from exploitation and other threats and as sources for recolonization of damaged reefs to increase ecological resilience."
The crown-of-thorns starfish in question have up to 20 arms covered in "evil-looking spines," Sweatman said. Not only do they look menacing, but those spines are also extremely sharp and carry a painful toxin.
When outbreaks occur, thousands of starfish dot the reef surface, interspersed by the pure white skeletons of recently consumed coral colonies. Sweatman said that even much lower densities of starfish have a very significant effect on coral cover. Eventually, the starfish on a reef are thought to die of starvation and disease, but their larvae are carried by currents to downstream reefs. "The living coral typically covers about 20 percent of the perimeters of reefs of the Great Barrier Reef. That figure drops to about 5 percent after an outbreak," he added.
