ABC News Report,-scientists-warn/9311280

Almost the entire green turtle population in parts of the northern Great Barrier Reef is now female, and scientists are concerned about their future.

Key points:

  • Warmer temperatures generally produce more female hatchlings
  • In northern areas 99pc of the juvenile and subadult populations were female
  • Scientists found for the past 20 years in some areas there had been no male hatchlings

A study published today in the journal Current Biology — led by the National Oceanic and Atmospheric Administration (NOAA) in the US and in conjunction with scientists from Australia — found the group of turtles had primarily produced females for two decades, because of increasing temperatures.

“Considering that sea turtle sex is dependent upon the temperature at which the egg incubates and considering that warmer temperatures produce more female hatchlings, we’re concerned climate change might be causing this effect,” Camryn Allen said, a marine biological researcher at NOAA.

“The pivotal temperature for sea turtle populations where they produce 50 per cent male and 50 per cent female is about 29 degrees Celsius.

“Any variation on that of about one to two degrees, could risk producing all females or perhaps embryonic death.

“The temperature on the Great Barrier Reef has been higher than that pivotal temperature.”