Scientists are alarmed over the existence of Australia's Great Barrier Reef after a swarm of at least a million starfish has been discovered moving toward the southern side. A crown of thorns plague has wiped out one reef between Cooktown and Cairns, according to the AAP.

"Well equipped to find and feed on coral," scientists said run-off from fertilizers on farms might have boosted the number of the starfish.

"Flood plumes during the cyclone season come laden with additional nutrients and sediments," Peter Doherty, Australian Institute of Marine Science spokesman, said.

"They promote intense plankton blooms that increase the size of the plant cells and provide perfect feeding conditions for the starfish, and a combination of that is suddenly an explosive increase in the numbers of starfish."

The crown of thorns, according to Col. McKenzie, head of the Association of Marine Park Tourism Operators (AMPTO), are multiplying.

"I would expect it would be 12 months before we'll see a full-on outbreak off Cairns."

Prof. Morgan Pratchett from the Coral Reef Studies Research Centre at James Cook University, said Australia needs to shape up the soonest.

"Clearly the impact of the crown of thorns starfish is one of considerable concern because these animals are very good at finding and feeding on the last remaining corals," he said.

"This is a very bad time to have a major outbreak of crown of thorn starfish," he added.

"We had a whole series of very severe cyclones which have already depressed coral cover and these crown of thorn outbreaks on top of that will really destroy what coral cover is left," he noted.

The Crown of Thorns starfish is a large multi-armed starfish that usually preys upon hard or stony coral polyps. Their numbers increased rapidly due to the huge quantities of agricultural fertilizers that were discharged into the Pacific Ocean triggered by the Queensland flood.

From millions, the Crown of Thorns starfish could turn into billions as the seawater's natural acidity level gets more acidic due to fossil-fuel emissions and growing sea temperatures.