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.