Scientists fear the already declining growth rate of the Great Barrier Reef’s corals will stop completely by 2050, killing off the reef and making way for algae.
A new report shows the most robust corals on the reef have slowed in growth by more than 14 per cent since the “tipping point” in 1990.
The paper, published in the international journal Science and written by scientists Dr Glenn De’ath, Dr Janice Lough and Dr Katharina Fabricius, shows evidence of a decline in the calcification rates in the Great Barrier Reef corals.
The Australian Institute of Science paper claims the decline has been caused by a combination of rising sea surface temperatures and ocean acidification.
Calcification is how much skeleton the coral puts down each year.
When large amounts of carbon dioxide enter the seawater, the resulting chemical change reduces a marine organism’s ability to form skeletons and protect itself against the environment.
Dr Lough said the evidence was alarming.
“It is cause for extreme concern that such changes are already evident, with the relatively modest climate changes observed to date,” she said.
Dr De’ath said according to the trends, coral would stop growing altogether by 2050 and be replaced by algae, to the detriment of biodiversity in the area.
“The data suggest that this severe and sudden decline in calcification is unprecedented in at least 400 years,” he said.
The situation would create a devastating chain reaction for species in the area. Dr De’ath said.
“Algae will take over the area, small fish will lose their habitat, then the larger fish that eat the small fish will starve,” he said.
Queensland Premier Anna Bligh said she was worried by increasing scientific evidence of the state of the reef.
The government has announced it will this year begin regulating chemical runoff from farming or agricultural activities into the reef for the first time.
“I know there is not a lot of farmers who are happy with my decision … but we have a special responsibility to look after it, and 2009 will see new laws that will further protect the Great Barrier Reef,” Ms Bligh said.