29 June 2012 Spotlight shines on the crown-of-thorns

COTS at Keeper Reef. Image: AIMS Long-term Monitoring team.

 Scientists from around the world will gather next week with reef managers to consider whether crown-of-thorns starfish (COTS) are a risk to the long-term sustainability of the Great Barrier Reef.

Dr Peter Doherty, past Research Director of the Australian Institute of Marine Science and Science Leader of the Tropical Ecosystems Hub of the National Environmental Research Program, has convened the meeting as a response to long term changes in coral cover on the Great Barrier Reef.

The AIMS Long-Term Monitoring Project (AIMS LTMP) was started after a major eruption of COTS in the nineteen seventies and eighties. Since 1985, the AIMS LTMP has surveyed coral cover annually on 100 coral reefs representative of the Great Barrier Reef. Shifts in coral cover over this 27 year period provide a wealth of important information about the changing health of coral reefs and the major disturbances causing loss of coral cover including another widespread outbreak of COTS in the nineties.

"Over the last three decades, tropical cyclones and storms, crown-of-thorns starfish, and coral bleaching have each taken their toll of coral cover", says Peter.

"Reefs are living things that recover naturally from disturbances but it takes 15-20 years to rebuild a similar coral community after a major outbreak of starfish reduces local coral cover to a few percent. In recent years, reefs recovering from one disturbance can get knocked down again by a second one and the net result of the cumulative pressures is that we have witnessed a slow erosion in the total amount of coral on the Great Barrier Reef", Peter adds.

"We can't do anything about cyclones, storms, or the coral bleaching caused by high sea temperatures but we may be able to do something about COTS", says Peter. "The workshop will consider the desirability and feasibility of some form of direct action although I can't tell you now exactly what form that might take."

AIMS Principal Research Scientist, Dr Katharina Fabricius, another who will contribute to the workshop explains, "Once there are multiple outbreak populations, it's too late to do anything other than deploy divers to defend local sites but this is expensive." On the GBR, this is done by divers injecting starfish with chemicals that are toxic to them but safe to the surrounding life.

"We welcome the government funding of marine tourism operators in removing crown-of-thorns starfish from key reef sites but it is our hope that science can come up with a more cost effective solution for large-scale control. However, we are not suggesting that this will be easy" she adds.

The workshop will be held on Fitzroy Island from 5th – 7th July, just before the 12th International Coral Reef Symposium in Cairns, and will pool knowledge about COTS outbreaks on reefs from countries as far apart as Japan, Hawaii, French Polynesia, Australia, the Seychelles, and Mauritius.

The workshop will cover topics including the role of water quality in promoting population explosions of crown-of-thorns starfish, and the success of different methods of control. The workshop is funded jointly by the Australian Institute of Marine Science and the Australian Government Department of Sustainability, Environment, Water, Population and Communities, through the National Environmental Research Program.

For further information:

Dr Peter Doherty, AIMS Fellow, NERP TE Hub Science Leader, 0418 469 770; p.doherty@aims.gov.au      

Wendy Ellery, AIMS media liaison, (07) 4753 4409; 0418 729 265; w.ellery@aims.gov.au