A NEW study has found corals off the WA coast grow more quickly when ocean surface temperatures are warmer.
Marine biologist Dr Tim Cooper, who led the research team, said coral reefs in eastern Australia, Thailand and the Red Sea had shown an alarmingly different trend, growing more slowly in recent decades.
His team from the Australian Institute of Marine Science (AIMS) took core samples from reefs in six locations at the Abrolhos, Ningaloo Reef and Rowley Shoals.
“We looked at the rates at which the corals had been laying down their skeletons for the past century and compared them to observed seawater temperatures, and quite surprisingly we did not find a widespread and consistent decline in coral calcification rates here in WA over the recent decades,” he said.
Dr Cooper said increased temperatures continued to coincide with increased coral growth in five of those locations, particularly at the Abrolhos and at Ningaloo’s Coral Bay and Tantabiddi.
A slight increase at Rowley Shoals was not statistically significant.
Dr Cooper said a similar trend had been observed at the Great Barrier Reef up until the early 1990s, when coral growth began to decline.
“On the Great Barrier Reef there has been a well-described relationship between sea surface temperatures and calcification rates in massive corals,” he said.
“Historically the growth rates have gone up and down but there tended to be—over the last 50 years—an increase with increases in sea surface temperatures.
“More recently in 2009 there was a big study that found a decline in coral growth rates that started in the early 1990s.”
He said research is needed into possible contributing factors.
“There’s different sorts of pressures that are potentially affecting the coral reefs on the east coast that we don’t see over here in Western Australia,” he said.
“The Great Barrier Reef is a maze of about 2900 coral reefs that all sit on a carbonate platform.”
“Western Australia has fewer isolated scattered reefs—some of the reefs we sampled were out in clear oceanic water.
“There are also … differences in oceanographic patterns running down both sides of the country and different ranges in sea surface temperatures.
“There are human influences (on Great Barrier Reef): several well-developed cities and a lot of agriculture,” he said.
In the meantime, AIMS is analysing core samples from Ashmore Reef to see if they show similar trends.
