BOCA RATON, Fla — We usually think about a summer downpour as relief from the South Florida heat.
But beneath the sand along our beaches, rain can have another effect and it can change the environment where thousands of sea turtle eggs are developing.
WATCH BELOW: Summer rain could save Florida's sea turtles from becoming all female
For sea turtles, temperature plays a major role in determining whether a hatchling develops as male or female. Warmer nest temperatures generally produce more females, while cooler temperatures produce more males.
That relationship is at the center of long-running research at Florida Atlantic University's Marine Science Laboratory at the Gumbo Limbo Environmental Complex in Boca Raton.
"All of the turtles are here right now because they're all part of this long-term sex ratio work, because you have to know if you're making enough boys and enough girls, and we're really concerned about that lack of boys," said Jeanette Wyneken, professor of biological sciences and director of the FAU Marine Science Laboratory.
Researchers have been studying sea turtle sex ratios along South Florida's coast for more than two decades. FAU says the work examines how the environment experienced by eggs during incubation — particularly temperature — affects the sex of the hatchlings.
Why rain matters
Temperature isn't the only part of the nest environment researchers watch.
Rain can cool the sand and add moisture around a nest. Previous FAU research comparing rainfall, sand temperatures, and hatchling sex found that heavy rainfall can lower sand temperatures, and that wetter years and cooler portions of the nesting season were associated with more male hatchlings.
That makes one stretch of weather from this summer particularly interesting to Wyneken.
"There was a period there when we had a lot of rain in the middle of August," she said. "And we may have both boys and girls."
Researchers believe many of the turtles that developed during some of the hotter conditions this season are likely female.
But the turtles that incubated through that wetter period could provide a different result.
"I get tired of doing hundreds of turtles and only seeing girls," Wyneken said. "It’s nice to see a boy once in a while."
Scientists won't know the final breakdown immediately.
Some of the oldest turtles being studied this season arrived at the laboratory in July and are only now reaching the size researchers need to confirm their sex.
"We'll wait and see," Wyneken said.
A question that could matter decades from now
The concern goes well beyond a single nesting season.
Sea turtles can take decades to reach reproductive maturity. If warmer conditions repeatedly produce heavily female-skewed generations, researchers want to understand what that could mean for future breeding populations.
FAU researchers have previously documented seasons dominated by female hatchlings along Florida's southeast coast, and the university says warming nest temperatures are an important reason scientists continue monitoring sex ratios over time.
Each season's hatchlings therefore become another year of data in a much larger picture — one showing how changes in temperature, rainfall, and the beach environment may affect sea turtles for generations.
How you can help
The research at FAU’s Marine Science Laboratory relies in part on philanthropic support. FAU says raising a leatherback hatchling for research can cost more than $1,000 per turtle, while caring for loggerhead and green turtles can cost about $120 per turtle.
Click here to support the FAU Marine Science Laboratory and sea turtle research.
The Florida Fish and Wildlife Conservation Commission recommends several simple steps during nesting and hatching season:
- Keep beaches clean, dark and clear at night; turn off or shield lights visible from the beach
- Give nesting turtles and hatchlings plenty of space and never handle them
- Fill in holes and remove chairs, umbrellas and other equipment before leaving the beach
- Pick up trash and discarded fishing line
- If you see a sick, injured, entangled or dead sea turtle, contact the FWC Wildlife Alert Hotline at 888-404-FWCC (3922)
