How does climate change threaten sea turtles?

One of the biggest worries of all conservationists is climate change. Climate change affects the ecosystem and the species’ ability to adapt. It is heart-breaking that one by one of our biodiversity is lost due to climate change. The more the change, the greater is the loss in biodiversity. We fear that someday these species that are present now will become extinct in the future when the conditions of the environment are outside the capabilities of the species to survive.

But first, let’s look at the definition of climate change. “Climate change” describes a phenomenon when the average climate conditions such as rainfall and temperature in a region changes over a long period of time. It results in the warming of the Earth and consequently, gives impacts on many biodiversity alike especially those that have a small range of optimum temperature for survival.

Sea turtles are one of the vertebrates whose survival is very much dependent on temperature. The increase in global temperature gives rise to the melting of the polar ice which causes the sea level to increase. Sea turtles are unique in such a way that many of them will return to the same beach from which they were hatched to lay eggs. This is distressing for us, conservationists as the condition of the beach may not be the same as before.

In a recent study to investigate the threats of climate change to sea turtles, nesting sites of sea turtles in Caribbean Islands were examined. From the study, the authors discovered that for every increase of 0.5 m in sea level, 1/3 of the total beach area could be gone. Out of the 13 beaches that the authors have surveyed, one particularly vulnerable beach could lose its entire suitable area for nesting habitat. At this rate, the point of impact could be described as “no return” for critically endangered species such as the hawksbill turtle. This, in fact, is a worrying state for all of us.

We also pose great concern over the gender of sea turtles because their sex ratio is threatened by the rise of global temperature. Like most alligators and crocodiles, the sex of all species of sea turtles is influenced by the incubation temperature. This is known as temperature-dependent sex determination, or TSD. To produce male hatchlings, the temperature during incubation must be below approximately 28°C and any temperature above 31°C will favour female hatchlings. Scientists expected the occurrence of just slightly more females than males but instead, the statistics shocked them as in the Pacific Ocean, they discovered that the number of females to males in the green turtle rookery was at least 166 to 1!

Warmer temperatures also bring about the alteration of sea currents. Sea currents are important in the navigation of sea turtles to migrate and find prey. Warmer temperatures cause their prey to exist outside of their normal range – for example, southerly species will occur in more northerly regions. This in turn, impacts the abundance of prey species at their usual range and potentially introduce the sea turtles to new predators.

What is most alarming is that the increase in temperature has impacted the sea turtles on such a large scale in the Great Barrier Reef in Australia – a place that has the largest population of sea turtles. So if we come to think of it, how much impact will it give to areas with extremely low populations? Will all the species in the area be wiped out one day? The sooner we get together, the sooner we can act to find solutions to save our sea turtles!

References:

1. Global warming & sea turtles. (n.d.). Retrieved February 26, 2021. Link.
2. Fish et al. (2005). Predicting the Impact of Sea-Level Rise on Caribbean Sea Turtle Nesting Habitat. Conservation Biology 19(2):482-491.
3. Sea turtles threatened by rising seas. (2007). Retrieved February 26, 2021. Link.
4. What is climate change? (2021). Retrieved February 26, 2021. Link.
5. Global warming & sea turtles. (n.d.). Retrieved February 26, 2021. Link.
6. Climate change puts pressure on sea turtles – climate change: Vital signs of the planet. (23 July 2019). Retrieved February 26, 2021. Link.