It is widely known that the sex of a reptile hatchling is largely dependant on the egg’s incubation temperature. This is why you often see crocodiles, turtles, and alligators build careful ‘incubation chambers’ on sandy shores to ensure that the population does not become dominant with a single sex.  In turtles, a higher temperature produces more females, with males produced by lower temperatures.

Global warming has caused an increase in the temperature of the ocean and the shoreline, leading to a high number of female births,according to latest research. The increase in sea temperatures is leading to more female sea turtles. Some populations under scrutiny are showing up to a 90% bias towards female hatchlings. This is extremely concerning for the future of turtles as a balanced sex ratio is vital to keeping population numbers up.

But a team of researchers from Bangor University have devised a cost-effective method to help change this massive disparage in the numbers of female turtles in the area. The published in the Journal of Applied Ecology, shows the potential for two interventions to reduce nest incubation temperatures and stabilize sex ratios in a nesting loggerhead turtle population in the Eastern Atlantic Ocean.

“We measured all sorts of elements related to the hatchlings,” said Dr. Clarke in the Bangor University press release, “including their size, weight, running speed and how fast they could right themselves, and importantly found no difference between the nests. These are really important, as hatchlings need to be able to avoid predators on the beach and when they make it to the sea.”

The area in Cape Verde (West Africa) was chosen because it is a popular Loggerhead Turtle nesting area. By transporting eggs from the site chosen by the turtles to safe ‘beachside hatcheries’ allowed the team to study and monitor the temperature in which the eggs incubated.

The team patrolled all common nest sites in search of fresh eggs that could not yet be hampered by the high temperatures of the shoreline. By doing so, they could effectively control the temperature of the eggs from when they were laid until they hatched.

“We would walk all night up and down the beaches and take eggs for our experiment from females as they nested.”The results give hope that simple management can help protect endangered sea turtle populations in a changing climate.

The team propose these efforts be carried out in other major nesting sites as well, where turtles are facing a change in sex ratio of hatchlings. They believe that this method is cost effective as it involves no major mitigation strategies of infrastructure but just sustained efforts to track eggs and incubate them in seaside labs. 

Most sea turtle species lay a vast number of eggs, sometimes ranging in the 100’s per female. This cluster sometimes raises the temperature in the centre of the incubation chamber, effectively preventing males from developing. The researchers believe that by separating large clusters into smaller, more manageable clusters could also help in reversing this issue. 

“Wildlife watching tourism, including sea turtles, generates significant amounts of revenue in areas with nesting populations, and sea turtles also graze on algae and seagrass and maintain healthy coral reef ecosystems. So conserving healthy populations in the future is really important.”

The paper, “Low‐cost tools mitigate climate change during reproduction in an endangered marine ectotherm,” is available via open access in the Journal of Applied Ecology.Dr. Leo Clarke, marine biologist at Bangor University and lead author of the study explained:

“Previous work has tested various techniques to reduce nesting temperatures in sea turtles, including sprinkling and shading of the nests and moving eggs to labs for incubation

The team wanted to avoid the use of significant infrastructure and make these solutions accessible to researchers across the globe with small budgets. Turtle nesting sites or ‘rookeries’ are often in remote locations and ideal solutions need to be simple and cheap. Therefore, applying some logic and coming up with simple and time-intensive efforts is the best way forward.

“We tested two interventions: nest shading, and a new technique that we call nest splitting. This involved halving the number of eggs in a nest, hopefully reducing the amount of metabolic heat that the eggs generate as they incubate and reducing temperatures.”

The team found that either method was effective in reducing the overall nest temperature, which allows more males to develop. Both techniques reduced nest temperatures compared to the nests created by the turtles themselves. Furthermore, the team also concluded that adding shade over the area where the eggs were laid decreased incubation temperatures by 1.1°C. Splitting the eggs in the nest also reduces incubation temperature by 0.5°C resulting. This improved the male female sex ratio by reding the number of female hatchlings from 69 percent to 53 percent. 

Also, these simple methods caused no issues to the health of the hatchlings and they were able to find their way to the ocean just as effectively as turtles that hatched in a natural turtle-made nest. Successful incubation and production of male sea turtle hatchlings is threatened by increased global temperatures (sex is determined by the temperature at which eggs incubate). Here we test two conservation tools to reduce incubation temperatures: clutch splitting and clutch shading, on a nesting loggerhead turtle Caretta caretta population in the Eastern Atlantic Ocean.

Impact of Findings

This shows that conservation is not about spending millions of dollars in research and infrastructure but involves careful and intricate understanding of the issue and coming up with solutions that help conserve a species without much human intervention. The design of nature is perfectly balanced and human intervention has thrown this off course. The way forward is not further using technology or infrastructure but helping the natural world attain balance through simple , effective and non-invasive ways.