Sea turtles are likely to be beneficiaries of a warming climate as hotter incubation conditions trigger a rising share of female hatchlings that could lift natural rates of population growth, new research to be published in Nature Climate Change on Monday shows.
But gains will be temporary if temperatures keep rising and nudge populations towards becoming all female, or exceed levels at which developing embryos die, the study found.
It has been known for decades that reptile reproduction is highly sensitive to temperature, with the ratio of male to female offspring varying. For species of sea-turtles, the pivotal temperature is an oddly uniform 29 degrees for incubation, beyond which more females emerge from the eggs.
At about 30.5 degrees, populations become fully female. As remaining males die off, ”it will be end of story without human intervention”, Professor Hays said. At higher than 33 degrees, embryos do not survive.
The study focused on a globally important loggerhead turtle rookery on the Cape Verde Islands in the Atlantic but its results also apply to species elsewhere, including the Pacific. It found light-coloured sandy beaches already produce 70.1 per cent females, while beaches with darker sands are at 93.5 per cent.
— Peter Hannam. source smh.com.au