Understanding the Gender Imbalance in Sea Turtles

Recent research indicates that warming ocean temperatures are drastically affecting the sex ratio of sea turtle hatchlings, with over 99% being female. This trend poses a serious risk to the survival of the species.

A green sea turtle emerges on Heron Island, Australia. The rise in water and sand temperatures in the Great Barrier Reef has led to a female-dominated population, as reported by The New York Times.

In many human contexts, certain fields are often labeled as “male-dominated,” yet the situation is quite different for sea turtles. A 2018 study revealed that the majority of sea turtles in the Great Barrier Reef are now female, largely due to the impacts of climate change, which jeopardizes the species' future.

Unlike humans, where sex is determined genetically through chromosomes, the sex of sea turtles is influenced by the temperature during incubation. For green sea turtles, the critical temperature, or pivot temperature, is around 85 degrees Fahrenheit, where the likelihood of hatching as male or female is nearly equal. However, as climate change continues to raise the temperatures of both ocean waters and nesting sands, the narrow temperature range for determining sea turtle sex is resulting in a trend towards near-total feminization.

The findings demonstrate that turtles nesting on cooler beaches in the southern Great Barrier Reef show a female ratio of 65%-69%, while those on warmer northern beaches exhibit an overwhelming female majority: 99.1% of juveniles, 99.8% of subadults, and 86.8% of adults.

Green sea turtles are not only visually stunning but also play crucial roles in maintaining the health of their ecosystems. Their absence would significantly impact ecological balance.

Identifying the sex of sea turtles can be quite complex due to the lack of external indicators and the absence of chromosomes. The recent study is groundbreaking as it introduces a non-invasive technique developed by co-author Camryn Allen, utilizing hormones to determine the sex of the turtles.

Determining sand temperatures was achieved through ethical historical methods. Researchers collected data on the nesting sands’ temperatures from 1960 to 2016, revealing a significant rise in temperatures by the 1990s, attributed to climate change.

Although the green sea turtle population is not facing immediate extinction, it is on a gradual decline as temperatures rise. While a small number of males can sustain the population temporarily—since one male can mate with multiple females—the ongoing trends suggest a worrying trajectory towards extinction.

While it's feasible for a limited male population to persist for a few more decades, proactive measures can be taken to mitigate temperature increases. Dermot O’Gorman, CEO of World Wildlife Fund Australia, suggests that shading beaches and reducing turtle bycatch in fisheries could help maintain the population for the time being.

Ultimately, addressing climate change and halting rising temperatures is the most effective approach. This study underscores the critical need for conservation initiatives to protect both wildlife and ecosystems. The decline of one species can have cascading effects on the entire ecosystem.

Climate Change's Effect on Sea Turtle Eggs

This video discusses how rising sand temperatures influence sea turtle hatchlings and their sex ratios, further emphasizing the urgency of conservation efforts.

Weather Impacts on Sea Turtle Eggs

In this video, experts from the Natural History Museum explore how various weather conditions affect sea turtle eggs, highlighting the challenges posed by climate change.