Heat Could Be Stifling Turtles’ Swimming Abilities In Australia

Zoologist Dr David Booth, from UQ's School of Biological Sciences, said green turtle hatchlings from Heron Island weren't swimming as well as usual.

“The 2008-2009 green turtle nesting season on Heron Island has seen the highest nest temperatures recorded at this site, with many nests having average temperatures above 31 degrees, and experiencing temperatures above 35 degrees during the last week of incubation,” Dr Booth said.

“Initial impressions are that hatchlings emerging from these hot nests are not as strong swimmers as hatchlings coming from cooler nests recorded in previous years.

“If climate change results in consistently high nest temperatures in the future, then the poorer swimming ability of hatchlings emerging from hot nests may have a negative impact on recruitment of hatchlings from coral cays because predation rate is thought to be related to swimming ability.”

Basing his research at the southern end of the Great Barrier Reef at UQ's Heron Island Research Station, Dr Booth took advantage of the unique laboratory facilities that are within metres of a green turtle nesting beach.

“My research involves going out and collecting fresh eggs as they're being laid by the females, moving them into other nests that are not going to get dug up by other females and then coming back about five to six weeks later to sample the hatchlings to measure their swimming performance,” he said.

“As we all know, the temperature of the earth is changing and as things warm up the nests are going to warm up and I was interested to see if that might have an affect on the quality of the hatchlings.”

Dr Booth said nest temperature determined the sex of sea turtles, suggesting that a warmer climate may have other implications for the endangered species.

“When the eggs are laid they can be either males or females,” he said.

“If it's a relatively cool nest they turn out to be males and if it's a relatively warm nest they turn out to be females.”

Previous research conducted by Dr Booth at Heron Island, and published in the Journal of Experimental Biology, investigated how much energy the hatchlings needed to reach safe deep water.

Calculating the amount of energy the hatchlings consumed during an 18 hour swim, Dr Booth said the turtles carried almost 10 times as much energy in their yolk remnants as they needed to reach safety.

“So the youngsters aren't at risk of running out of energy before making it to safety,” he said.

“They can probably survive 14 days in the open ocean before finding food.”