Researchers believe cyclones and flooding earlier in the year have wiped out the sea grass beds on which the turtles feed.
Oliver Milman guardian.co.uk, Thursday 18 August 2011 09.53 BST
Unusually large numbers of dead and dying sea turtles are washing up on Australia's Great Barrier Reef coast, prompting environmental groups to warn of a wildlife crisis in the region.
Researchers and local residents have reported that several Queensland beaches have been strewn with the carcasses of the animals, with wildlife centres in the northern city of Townsville inundated with ailing turtles.
According to the Queensland state government, 649 turtle deaths were reported in the first seven months of 2011, up 200 on the same period last year.
Dugongs are also suffering badly, with 96 of the aquatic mammals reported dead in the first seven months of the year, compared with 79 in the whole of 2010.
Sick and starving turtles have been observed approaching the shallows, where they invariably die. Researchers believe that a severe loss of sea grass, the turtles' staple food source, is to blame for the escalating death toll.
Widespread floods and the subsequent Cyclone Yasi, which hit northern Queensland in February, wiped out around 90% of the seagrass in certain areas of the Great Barrier Reef coast.
Fred Nucifora, director of Reef HQ Aquarium, told the Sydney Morning Herald that the centre's turtle hospital is running at full capacity, with 15 turtles now being cared for.
“The turtles that are presenting are highly emaciated, they are suffering from not having enough food,” he said.
Queensland's recent natural disasters have heaped further pressure on turtle numbers, which face numerous other threats.
An Australian government report released last week revealed that agricultural pesticides released by farmers have swept across the Great Barrier Reef, causing damage to coral and wildlife.
Endangered species such as the leatherback turtle and green turtle have also seen their numbers dwindle due to fishing nets and boat strikes.
“In the past, turtles have been healthy enough to deal with extreme weather events, but the combined pressure of more fishing nets, declining water quality and associated disease, on top of the loss of critical habitats as a result of large coastal developments have all undermined their chances of survival,” said Cliff Cobbo, a conservation manager at WWF Australia.
WWF has urged the Queensland government to overhaul regulations surrounding fisheries and coastal development, as well as reduce the amount of pollution released into the sea.Vicky Darling, Queensland's environment minister, said that a panel of marine scientists will explore the causes of the turtle deaths and draw up recommendations to combat the problem.