Killer starfish blamed as Great Barrier Reef loses half its coral

Crown of Thorns starfish

Crown of Thorns starfish have poisonous spikes, up to 21 arms and an appetite for living coral

LAST UPDATED AT 13:41 ON Tue 2 Oct 2012

THE GREAT Barrier Reef has lost half its coral in the last 27 years, according to a new study which has shocked scientists and prompted a "call to arms" against a giant killer starfish.

The Australian Institute of Marine Science monitored 214 individual reefs along the World Heritage site and found that coral cover decreased from 28 per cent in 1985 to 13.8 per cent this year.

If extrapolated to the Great Barrier Reef as a whole, the figure equates to a loss of almost 19,300 sq miles of coral – more than twice the area of Wales, reports The Daily Telegraph. Without intervention, coral cover could fall by another half over the next 10 years.

Researchers were shocked at the rate of decline. Mark Eakin, coordinator of the National Oceanic and Atmospheric Administration's Coral Reef Watch programme, told The New York Times: "I never considered it untouchable. We just looked at it as not having been hit hard yet."

John Bruno, a professor of marine sciences at the University of North Carolina-Chapel Hill, said: "The rate of collapse has caught me by surprise, and I do a lot of this gloom and doom stuff."

The study attributed 48 per cent of coral loss to cyclones and 10 per cent to coral bleaching. The remaining 42 per cent was blamed on the Crown of Thorns starfish. The giant predators, which have up to 21 arms covered in poisonous spikes, can each consume up to 107 square feet of living coral per year. Population booms in the species are thought to be triggered by the run-off of fertilisers from the land into the sea.

The study has prompted a "call to arms" against the reef-killing starfish, says The Australian.

Hugh Sweatman, leader of the New Australian Institute of Marine Science's long-term reef monitoring programme, told the newspaper: "Tourism operators currently poison the starfish to protect high-value bits of reef but you can't do that on a large scale. Other possibilities should be investigated such as biological controls."

Removing the starfish threat would boost coral recovery by almost one per cent each year, he added.

Others have called for more action on the longer-term challenges posed by climate change, such as cyclones and coral bleaching.

Professor Ove Hoegh-Guldberg, head of the Coral Reef Ecosystems Lab at the University of Queensland, told academic research website The Conversation that the results make for “an extremely large smoking gun”. The only sensible remedy is to reduce global CO2 emissions to zero within the next 10 to 20 years, he said.

John Gunn, chief executive of the Australian Institute of Marine Science, told The Times: "We get very depressed about it at times. The Australian Government is committed to saving the reef and has put millions toward improving biodiversity but we need the global community to understand that something has to be done about ocean warming and acidification if we really have a chance to save it." · 

For further concise, balanced comment and analysis on the week's news, try The Week magazine. Subscribe today and get 6 issues completely free.