A recent study led by researchers from Griffith University in Australia has added to the growing body of research examining the impact of global warming and pollution on the reproductive processes of endangered sea turtles.
Published in the journal Frontiers in Marine Science, the study revealed that exposure to pollutants such as heavy metals (including cadmium and antimony) and organic contaminants can influence the sex of the offspring of green sea turtles (Chelonia mydas).
Arthur Barraza, a researcher at the Australian Rivers Institute at Griffith University and one of the study’s authors, explained, “Sea turtles’ embryos develop with temperature-dependent sex determination, leading to an increasing number of females as temperatures rise.
Our research indicates that the risk of extinction due to a shortage of male green sea turtles may be exacerbated by contaminants that also impact the sex ratio of developing green sea turtles, further skewing the population towards females.”
The study authors noted that over 99% of hatched sea turtles near the Great Barrier Reef are already female, underscoring the urgency of addressing the complex interplay of factors affecting the survival and reproductive success of these iconic marine creatures.
Researchers conducted a study of sea turtles on Heron Island, where the sex ratio is relatively balanced, with approximately two to three female sea turtle hatchlings for every male.
They carefully collected 17 clutches of eggs within two hours of being laid by the mother sea turtle and reburied them near temperature probes for further observation.
The study revealed that heavy metals and organic contaminants, including polychlorinated biphenyls (PCBs), exert an influence on the sex of hatchlings.
Many of the nests predominantly yielded female hatchlings, and researchers observed a correlation between nests with higher trace elements, particularly cadmium in the liver of hatchlings, and a greater female bias.
Jason van de Merwe, senior author of the study and a marine ecologist and ecotoxicologist at the Australian Rivers Institute, explained, “These contaminants are known or suspected to act as ‘xenoestrogens’ or molecules that bind to receptors for female sex hormones.
Female turtles accumulate these contaminants at foraging sites, and as the eggs develop within her, they absorb the accumulated contaminants, which are then sequestered in the liver of the embryos, persisting for years after hatching.”
Previous research has established that global warming is impacting sea turtle reproduction, as temperature influences the sex of offspring, potentially resulting in fewer male hatchlings with rising temperatures.
This poses significant concerns for the reproduction and genetic diversity of endangered sea turtles, as highlighted by the Sea Turtle Conservancy.
Another study, published earlier this year, found that sea turtle development is also affected by microplastic pollution.
The presence of microplastics in the sand can prevent it from cooling overnight, leading to elevated sand temperatures that can impact sea turtles.
Van de Merwe emphasized, “Given that most heavy metals originate from human activities such as mining, runoff, and general urban waste pollution, the optimal approach is to implement science-based long-term strategies to reduce the influx of pollutants into our oceans.”
Things We Can Do To Help Sea Turtles
Sea turtles, with their enigmatic and graceful presence, captivate our imagination. However, the unfortunate reality is that this magnificent species teeters on the brink of extinction, largely due to human impact.
As conscientious stewards of the planet, it is incumbent upon us to take decisive action to aid these remarkable creatures. Here are several proactive steps we can take to make a difference for sea turtles today:
1. Refrain from discarding plastic waste on beaches or into the ocean, as this can pose a grave threat to sea turtles and other marine life.
2. Safeguard and preserve the nesting areas of sea turtles, as these zones are critical for the continuation of their life cycle.
3. Avoid using flashlights, sound systems, and recreational equipment in nesting areas, as these disturbances can disrupt the natural behavior and breeding activities of sea turtles, potentially jeopardizing their survival.
By conscientiously adhering to these measures, we can play a pivotal role in safeguarding the future of sea turtles and contribute to the preservation of this vulnerable species for generations to come. Learn more here to help sea turtles, 12 Things We Can Do To Help Sea Turtles Today!