"While rising temperatures may initially result in increased female population sizes, the lack of male turtles will eventually impact the overall fertility of females in the population".
The proportion of female hatchlings increases when nests are in warmer sands, while cooler temperatures is known to produce more male turtles.
Maybe in future, there will be only male turtles. Majority of sea turtles from warmer northern beaches, on the other hand, were female, with 86.8 percent of adult turtles, 99.8 percent of sub-adult turtles and 99.1 percent of juvenile turtles turning out to be female. With rising temperatures, no more males would be around to mate with females, which could ultimately crash the whole population of sea turtles.
"This research is so important because it provides a new understanding of what these populations are dealing with", Michael Jensen, the study's lead author and a marine biologist with the National Oceanic and Atmospheric Administration, said in a statement.
The study used an innovative combination of endocrinology and genetics to assess the sex of hundreds of turtles across a large foraging ground, revealing the sex ratio of immature and mature turtles from different nesting beaches over many years.
Green sea turtles are already considered endangered, with the latest findings posing a dire new threat to the future of the species. Also, not only the higher temperatures affect the sex of the turtles but also increase mortality rates in turtle offspring.
Two-year-old Green Sea Turtle “Sea Biscuit”
There are two distinct populations of green sea turtles along the Great Barrier Reef.
"Our study highlights the need for immediate management strategies aimed at lowering incubation temperatures at key rookeries to boost the ability of local turtle populations to adapt to the changing environment and avoid a population collapse - or even extinction".
After collecting 411 for analysis and release, they found a "moderate female sex bias" in turtles from beaches in the cooler, southern Great Barrier Reef, where about 65-69 percent were female.
For now, the important matter is to look into the current sex ratios in the adult breeding population, and what they might look like after some years from now when these young turtles grow up, Jansen stated.
World Wildlife Fund Australia head Dermot O'Gorman told the Guardian Australia that environmental change was taking a quiet toll on creatures.