September 19, 2024 – The effects of climate change are all around us, from extreme weather patterns to the spread of infectious diseases. There is mounting evidence that our oceans are getting warmer, and this temperature change is having a major impact on sea turtle health. And rising temperatures are affecting these unique creatures in another way – they’re shifting the population toward more female turtles than males.
While someone famous once said that “girls run the world”, this change could have serious consequences.
“We know the sex of sea turtle hatchlings is determined by temperature,” said Dr. Lara Croft, Veterinary Scientist at the Foundation. “Investigating how a warming climate impacts sea turtle sex ratios and health on a population level is critically important to understand the future viability of sea turtle species and what management strategies may help mitigate negative impacts.”
The math is obvious – more females and fewer males will result in lower egg counts and hatchlings. It also could lead to a decrease in genetic diversity, since only a few males will be available for breeding.
The shift in sex ratio isn’t the only problem rising ocean temperatures cause for sea turtles.
“Beyond changes in hatchling sea turtle sex ratios, rising temperatures can negatively impact sea turtles in many other ways,” added Dr. Croft. “Warmer oceans can lead to loss of beach nesting habitats secondary to sea-level rise or erosion from severe storms. It can affect hatchling development leading to lower survival rates, change the distribution and abundance of food, and alter ocean currents that change migration routes.”
In a new Foundation-funded study, researchers at the Mote Marine Laboratory & Aquarium will monitor the temperature of loggerhead and green sea turtle nests across a large rookery in Sarasota County, Florida. The team will place mobile weather stations near beaches to collect local air temperature and precipitation levels. Sea surface and land surface temperatures will be scraped from both NOAA and Google Earth. Finally, nest excavation data will be collected to assess nest depth and hatch success.
The team will then take these data and determine which factors have a significant effect on nest viability and potential hatchling sex ratios. The team will also be assessing a new methodology on loggerhead nests to decrease nest temperature–improving the likelihood of a 50/50 sex ratio. If this method proves useful, beach managers could use it to help mitigate overwhelming bias in sex ratios of these threatened species.
The Foundation has been investing in sea turtle health studies for two decades. Our research has helped inform new rehabilitation practices, revolutionized the way sea turtles are treated for red tide exposures, and led to the development and validation of measures of sea turtle health. But we still have a lot to do to save these amazing animals.
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