( A masked marauder has emerged unexpecte...)Batfish to the rescue!

With the dramatic flair of comic-book superhero Batman, a batfish has saved a coral reef that was being choked to death by seaweed ?although the fish was never previously known as a weed-eater.

Scientists at the ARC Centre of Excellence for Coral Reef Studies (CoECRS) who were studying how coral reefs are lost to weed were astonished when, after removing a cage from a particularly weedy bit of reef, the rare batfishes emerged out of the blue and cleaned up most of the weed.

"Worldwide, coral reefs are in decline," says Professor Dave Bellwood of CoECRS and James Cook University. "Commonly this takes the form of the coral being smothered by weedy growth, a transition known as a phase-shift which is very hard, if not impossible, to reverse."

"Research internationally has found that a major factor in this shift is the over-fishing of weed-eaters like parrot and surgeon fish ?which normally keep the coral clean of weedy growth."

Prof. Bellwood and colleagues Prof. Terry Hughes and Andrew Hoey were testing a weed-infested patch of coral near Orpheus Island on Australia's Great Barrier Reef to see whether local herbivorous fish could restore it to a normal state.

The ensuing action was captured on underwater TV cameras. When the cage was removed from a particularly weedy patch, local herbivores pecked at it but made little impression on the dense growth of sargassum weed.

"Then these batfish showed up and got stuck into it. In five days they had halved the amount of weed. In eight weeks it was completely gone and the coral was free to grow unhindered," Prof. Bellwood explains.

The turnaround was due mainly to one species of batfish, Platax pinnatus, which is comparatively rare on the GBR and was thought to feed only on invertebrates.

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Source:James Cook University