A recent study published in Frontiers in Marine Science suggests that heavy metals ingested by female green sea turtles (Chelonia mydas) while foraging for algae and sea grass may be causing a skewed sex ratio in their offspring.
The study, titled “Exploring contaminants as a disruptor of temperature-dependent sex determination in sea turtle hatchlings,” examines data from other reptile species such as alligators, freshwater turtles, and caimans, and how contaminants can alter the sex ratio in these temperature-dependent species.
The researchers, from the Australian Rivers Institute, University of Environment and Science, Griffith University, Gold Coast, QLD, Australia, The University of Queensland, University of Sunshine Coast, and World Wildlife Fund for Nature-Australia, suggest that contaminants present in sea turtle foraging areas may be transferred to the eggs by the mother, resulting in exposure to these contaminants and potentially affecting sex determination in green sea turtle hatchlings.
It has been observed that certain populations of green turtle hatchlings on Raine Island off the coast of Australia have had a 99% female hatchling rate for the past 20 years. This means that male hatchlings are outnumbered by females at a ratio of 116 to 1.
The study found that contaminants such as cobalt, lead, barium, and cadmium were present in hatchling livers and had significant effects on sex ratio and sex ratio deviation. Out of 16 clutches examined, “11 had more females than predicted (8 – 90% more females), three had more males (9 – 33% more males), and two matched the predicted sex ratio,” the study showed. These contaminants have also been shown to skew sex ratios in other animals such as zebrafish, pond sliders, snapping turtles, and pejeery fish. Cadmium is a known endocrine disrupting compound and has been found to alter the transcription of two genes in certain freshwater turtles.
The researchers note that while the study cannot pinpoint a specific contaminant that feminizes sea turtle hatchlings, it does demonstrate that chemical mixtures can potentially affect sex ratio and sex ratio deviation, leading to a trend towards feminization.
This is such an important topic to shed light on. It’s devastating to think about the potential impact on sea turtle populations.
Wow, I had no idea that contaminants could have such a profound effect on sea turtles. Our actions and pollution have far-reaching consequences we need to address.