The male sea turtle is a rather promiscuous creature, so it suits him to be naturally outnumbered by the female of the species. But the Great Barrier Reef Marine Park Authority is wondering if male turtles will be so outnumbered in future the species will fail to breed.
The authority is concerned that global warming will push up the temperature of turtle eggs as they incubate in sand. The warmer the egg, the more likely the hatchling will be female.
Females hatch if the egg is around 30 degrees, while 28 degrees produces a male.
While the natural population can be female-skewed, says the authority’s species conservation unit manager Dr Kirstin Dobbs, males obviously play a key role.
“You do need both sexes to (breed) so you don’t want temperatures getting too high and not having any male turtles produced.”
The authority is also concerned that the predicted increase in extremely hot days will kill the turtles before they hatch. Extreme temperatures of 33 degrees have been noted on some turtle nesting spots already. Just one more degree and the animals die.
Scientists are expecting a warming of at least 1.5 to 2 degrees this century. If greenhouse emissions are not cut, the warming could reach 5 degrees or more in the worst case scenario.
The chilling effect of warm changes in Australia:
? One degree’s warming will bring significant coral bleaching, a 2 to 2.5 degree rise would be catastrophic to corals.
? Two degrees’ warming will cause the rapid loss of habitats for many species; up to a 20 per cent loss in river flows.
? 2.5 degrees brings a significant loss of alpine areas for both recreation and the species that live there.
And around the world:
? 1 to 2 degree increase in temperature will put millions at risk of food and water shortages.
? 2 to 3 degrees sparks the irreversible melting of the Greenland ice sheet, leading to a seven-metre increase in sea levels over 1000 years.
? 2 to 4 degrees melts the West Antarctic Ice Sheet, adding four to six metres of sea level rise.
Source: The Age (Australia)