A recent study conducted by Florida State University revealed that high concentrations of microplastics in beach sand can lead to elevated temperatures that pose a threat to the development of sea turtle eggs. The research, published in Frontiers in Marine Science, highlighted the crucial role of healthy beaches for the successful incubation of sea turtle eggs.
Lead author Mariana Fuentes, an associate professor at FSU's Department of Earth, Ocean, and Atmospheric Science, emphasized the significance of temperature on sea turtle sex, fitness, and hatchling success. However, the impact of microplastic presence on the thermal conditions of nesting grounds remains largely unknown. Understanding how environmental changes can influence nesting ground temperatures is vital for monitoring the future of these essential marine species.
To investigate this issue, the researchers mixed sand from FSU Coastal and Marine Laboratory beaches with black and white microplastics. The concentrations of microplastics ranged from 5% to 30% of the total sediment volume. Digital thermometers were buried at the typical depth where loggerhead sea turtles lay their eggs, and temperature measurements were recorded from July to September 2018.
The study revealed that samples with higher concentrations of microplastics exhibited greater temperature increases. The sample containing 30% black microplastics showed the highest mean temperature difference, being 0.58 degrees Celsius warmer than the control group. Such temperature increases could have significant implications for sea turtle hatchling sex ratios, physiological performance, and embryo mortality.
Encouragingly, the study also indicated that the 30% microplastic concentration used in the experiment, equivalent to approximately 9.8 million pieces per cubic meter, surpasses the current highest concentrations found on beaches worldwide. Existing research has reported a maximum of about 1.8 million pieces per cubic meter.
However, the quantity of microplastics at nesting sites remains relatively unexplored, and it is plausible that higher concentrations exist in locations that have not yet been studied. Additionally, the demand for plastic is predicted to increase in the future, potentially exacerbating the issue.
Nesting sites where incubating eggs are situated near a critical temperature boundary of 29 degrees Celsius may be particularly vulnerable. Below this threshold, most hatchlings are male, while above it, most hatchlings are female. Even smaller concentrations of plastic could push the temperature beyond this crucial threshold.
Fuentes emphasized that sea turtle eggs are highly sensitive to temperature, and microplastics further contribute to the heat they experience. This study provides a foundation for future research on how microplastics affect the nesting environment and underscores the need for further investigation into this issue.
Source: Florida State University