Experimental process overview showing: a) black and white microplastics, b) sand and mixing tool, c) pouring sand and microplastics into a container, d) transporting containers at FSU’s coastal and offshore laboratory, e) container top view, f) another view A mesh screen is shown above the holes, and g) the experiment site. Credit: Mariana Fuentes
New research from Florida State University is published in Frontiers in Marine Sciences He found that extreme concentrations of microplastics can increase the temperature of beach sand enough to threaten the growth of incubating sea turtles.
Sea turtles play a vital role in the marine ecosystem, and for these oceanic reptiles to thrive, they need healthy beaches where their eggs can successfully incubate.
“Sea turtle sex, fitness and hatching success are affected by temperature,” said lead author Marianna Fuentes, associate professor in the Department of Earth, Ocean and Atmospheric Sciences at the University of Vosovo.
“Little is known about how the presence of microplastics affects the thermal profile of sandpipers. Understanding how changes in the environment affect the temperature of nesting areas is important for monitoring the future of this keystone species.”
The researchers mixed sand from beaches at FSU’s Coastal and Marine Laboratory with black and white microplastics. Microplastic concentrations ranged from 5% to 30% of the total volume of the sediment sample. Then they recorded temperatures from July to September 2018 by burying digital thermometers at the same depth at which loggerhead sea turtles lay their eggs.
They found that samples with higher concentrations of microplastics had larger increases in temperature, with the sample containing 30% of the black microplastics having the highest average temperature difference. These samples were 0.58 °C warmer than the control group, an increase that can significantly alter hatchling sea turtle sex ratios, physiological performance, and embryonic mortality.
The good news from the study is that the concentration of 30% microplastics in those samples equates to about 9.8 million pieces per cubic meter, which is a higher concentration than what is currently found on beaches around the world. The current research found the highest reported concentrations collected from beaches to be around 1.8 million pieces per cubic metre.
But the amount of microplastics at nesting sites has only recently been explored. It may be higher in locations not yet studied, and the demand for plastics is expected to increase in the future.
In nesting areas where the hatching eggs are near the 29 °C boundary—below which most chicks are male, and above which are female—smaller concentrations of plastic may be sufficient to push the temperature beyond the critical threshold.
“Sea turtle eggs are sensitive to temperature, and microplastics are another factor added to the heat they experience,” Fuentes said. “This study gives us a basis for future research on how it affects the nesting environment.”
more information:
Mariana MPB Fuentes et al, The Effects of Microplastics on the Thermal Profile of Sand: Implications for Sea Turtle Nesting Areas, Frontiers in Marine Sciences (2023). DOI: 10.3389/fmars.2023.1146556
the quoteResearchers: Sand warming from microplastics may affect sea turtle development (2023, June 13).
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