Weed-eating fish key to coral reef survival say experts

by Rich Bowden - Mar 21 2008, 02:47

A fish which lives on weeds that threaten the growth of new corals may be the key to protecting the Great Barrier Reef from damage an expert has said.

Australian Research Council (ARC) Centre of Excellence for Coral Reef Studies and James Cook University researcher Professor David Bellwood has said the herbivorous rabbit fish is capable of clearing large areas of vegetation which interfere with the regeneration of corals.

"When a coral reef is weakened or damaged through human activity such as climate change or pollution or by a natural disaster like a cyclone, the coral will usually recover provided it is not choked by fast-growing marine algae," Prof Bellwood said.

"The problem is that over the years we have fished down the populations of fish that normally feed on the young weed to such a degree that the weed is no longer kept in check - it can now smother the young corals and take over."

He added that observations had shown the insignificant looking rabbit fish, which had almost been overlooked in the past, turned out to be a coral's lifesaver.

"To our surprise and disappointment, the fish that usually mow the reef - parrot fish and surgeon fish - were of little help ... then, to our even greater surprise, a fish we had never seen in this area before was observed grazing on the weed," Prof Bellwood said.

At a briefing to parliamentarians in Canberra, the scientists said rebuilding fish populations was vital in areas of the Reef likely to be damaged by climate change, pollution and natural events such as cyclones. 

"The Great Barrier Reef is still a resilient system... and herbivorous fish play a critical role in that regenerative capacity, by keeping the dead coral space free of algae, so that new juvenile coral can re-establish themselves," said Professor Terry Hughes also from James Cook University in Townsville.

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