EXPERTS are scratching their heads after a clutch of turtle eggs were laid on a Sunshine Coast beach four months out of season.
In what’s believed to be a first for the South-East Queensland shoreline, the unexpected winter nesting occurred at Mudjimba Beach, 110km north of Brisbane, in late July.
Experts have confirmed the tracks seen where the eggs were found belonged to the endangered loggerhead turtle.
Why is winter nesting so unusual?
Taking nine to 10 months to produce functional sperm, male loggerhead turtles usually do not produce viable sperm earlier in the year. As they are known to have a mating season that only lasts for about a month, the males habitually mate during the months of October, November and December.
Sunshine Coast Council TurtleCare Co-ordinator, Kate Winter were alerted to the out-of-season nesting in time to join with Coolum & North Shore Coast Care volunteers and, together, they painstakingly retrieved 93 eggs.
Since any rotation could have caused an embryo to rupture and die, the task of extracting the eggs was done with great care.
Each egg was gently weighed and measured before being placed into containers of moist sand, along with a compass on top to lessen the risk of unnecessary movement.
The eggs were then transferred to a Sunshine Coast Council depot where they were inspected to check for viability before being placed in an incubator.
Sherida Holford, a volunteer with Coolum & North Shore Coast Care said, the process of relocating the eggs into the incubator was “slow and tedious”.
“We had three containers full of eggs and then we had to drive them to the Sunshine Coast depot,” Sherida said.
There was elation all round when 84 of the eggs proved to be viable.
Why are loggerheads endangered?
International turtle protection society, seeturtles.org, notes that, with warming air temperature, melting polar ice has led to rising of sea levels that, in turn, have seen the loss of beach shorelines. These sandy seaside stretches are where turtles, including loggerheads, like to lay their eggs.
Global warming has also been associated with severe weather, bringing harsher and numerous storms that further erode beaches and flood nests.
“As the overall temperature of the earth rises, so does the temperature of the sand, which diminishes the rate of hatchling survival,” seeturtles explains on its website. “The temperature of the sand also affects gender, as higher temperatures have been shown to yield more female hatchlings.”
Climate change can also influence currents and alter the number and location of prey species.
According to National Geographic, sea turtles face a raft of threats in a warming world.
Temperature changes could lead to skewed sex ratios, as warmer sands tend to produce more female hatchlings.
More extreme weather events can lead to storm surges that inundate turtle nests and destroy nesting beaches.
Rising sea levels will steal vital beach nesting habitats while rising temperatures could also lead to complex changes in ocean currents, which could see hatchlings end up in unsuitable areas for survival and growth.
Sea temperature and acidity rises may limit the growth of sea grasses and other fodder for turtles.Increasing air humidity could make eggs more susceptible to disease, resulting in higher mortality.
Had the eggs been left in the cold sand overnight, local turtle experts say, it’s doubtful any would have survived to hatch.
The eggs will now stay in their climate-controlled incubator for about 60 days before they hatch and are released back onto the beach at Mudjimba to make their way back out to sea.
UPDATE: Seven News reported that 36 hatchlings were released at Mudjimba on September 12. The following day another 15 were released, as shown above.
Words: Debra Harrip
Images: Sheryl Wright; Debra Harrip / The Argus
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The original version of this story is one of 30 in a special online Climate Change edition of The Argus that was compiled by Queensland College of Art students from a final-year course called Transmedia Storytelling.