Last year, Australia’s Great Barrier Reef saw bleaching en masse second time in a row. A scientific survey of the region suggested that the northern end of the reef had been bleached to bone white owing to a rise in the seawater temperatures. And now a new research suggests that the rising temperature not only damaged the coral reefs but also the aquatic life in the region.
A stark example of this devastation is — Green Sea Turtle.
The green sea turtle is found in the Atlantic and Pacific oceans and gets its name from the green-coloured fat tissue under its shell. Unlike other species of sea turtles, they are herbivores and they feed on seagrass and algae.
A new study published in the journal Current Biology found that 99 percent of green sea turtles found in the northern end of the Great Barrier Reef were female — which in turn poses a serious threat to the survival of this endangered species. The research suggests that the reason for this devastating trend is ‘climate change’.
How is climate change affecting the sex of green sea turtles?
Unlike in humans in whom chromosomes determine the sex of the embryo, turtles develop into males or females based on the temperature outside the egg. In sea turtles, cooler temperatures produce male hatchlings, while warmer temperatures mature the eggs into female turtles. At temperatures above 29.3°C, embryos will mature into female hatchlings.
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Researchers found out that while a vast majority (99 percent) of the turtles in the warmer northern region of the reef were females, only 65-69 percent turtles in the cooler southern region of the reef showed a skewed sex bias. But there’s more. The northern region of the reef has been producing female turtles for more than two decades. Here’s what they wrote:
Combining our results with temperature data show that the northern GBR green turtle rookeries have been producing primarily females for more than two decades and that the complete feminization of this population is possible in the near future.
How will this affect the aquatic life?
While rising temperatures may affect the sex ratio of the green sea turtles in the northern region of the reef, research suggests that the lack of male turtles will impact the overall fertility of female turtles, eventually forcing the species to extinction.