Sex Change

Besides the tranquil sea and sun-bleached sand,

The turtles find a place to make their nest;

Probing the rolling crescents of the land,

To find a place where incubation’s best.

Now buried like a golf ball in a dune,

The eggs begin to undergo great change;

To their surroundings they must now attune,

With gender predisposed by temperate range.

And when the stifling heat begins to rise,

The fate of all these eggs becomes more skewed;

Resulting in a masculine demise,

And higher rates of death in any brood.

The turtles’ destines are now entwined,

With climate change induced by humankind.

This is a Shakespearian Sonnet, inspired by recent research which has shown that climate change has caused populations of green sea turtles from the northern Great Barrier Reef to be nearly entirely female.

The sex of a green turtle is influenced by the temperature of the surrounding area of the nesting sites (rookeries) in which the fertilised eggs are lain.  The pivotal temperature is defined as the incubation temperature range over which 50% of each sex will be produced, but it is only a few degrees Celsius, and for green sea turtles, eggs which are incubated above 31 degrees Celsius will be all female, whilst those that have been incubated below 27.7 degrees Celsius will all be male.

Increases in the temperature of the northern part of the Great Barrier Reef brought about by climate change have had a profound effect on sexual diversity amongst the green sea turtles in this region. This new research has shown that 99% of green sea turtles born here are female, with 86.8% of all adult sea turtles in this region now female as well, meaning that there are severe implications for future breeding and species survival. Furthermore, increased incubation temperatures also lead to a higher egg mortality rate. With average global temperature predicted to increase by approximately 2.6 degrees Celsius by 2100, many sea turtle populations are now in severe danger of dying out.

An audio version of this poem can be heard here.