Sea turtles, a conservation success story, face new threat

Each March, sea turtle nesting season begins with the females’ slow-yet-determined scooch onto Florida’s shores, shoveling away sand with her speckled fins, digging a hole to lay eggs.

The season peaks around late spring to summer before tapering off in October, meaning Florida’s thousand-mile stretch of coastlines becomes home to hundreds of thousands of potential hatchlings during the worst of hurricane season. Now, those nurseries are threatened by increasingly stronger storms.

Hurricane season lasts from June 1 to Nov. 30, overlapping with the bulk of the sea turtle nesting window. The 2024 season saw the earliest Category 5 Atlantic hurricane on record when Beryl formed in July. Later in the season, Hurricanes Helene and Milton made landfall in Florida within 13 days of each other, devastating the state’s Gulf Coast.

Heavy rains, winds and storm surges pile on the threats to sea turtles. Nests can drown or wash away — as hundreds did after Hurricane Debby in August — while the erosion of beaches may leave future sea turtles with less area to nest.

Scientists link increasing hurricane intensity, along with sea rise that causes higher coastal inundation, to climate change. Warming temperatures allow tropical disturbances to draw more power from the oceans.

Hurricanes have always interfered with the incubation of turtle nests tucked in the sand, but stronger storms mean stronger interference. The changing conditions raise questions about the future of sea turtles, an endangered animal that has played a crucial role in marine ecosystems for the past 100 million years.

“Climate change is impacting our nesting beaches,” said sea turtle biologist Dr. Jake Lasala, “whether we like it or not.”

Rising tides and sea turtle nests 

They usually come at night — because temperatures are cooler then, mother sea turtles are less likely to overheat as they crawl up the shore. Some settle for low areas by the high-tide line; others inch their way to the base of the dunes. Each leaves her eggs, about 110 per nest, buried 2 feet deep in the sand.

The mothers might return to the beach up to eight times a season, laying new nests in new places and positions. This behavioral flexibility means “turtles don’t put all their eggs in one basket,” said Cat Eastman, a sea turtle hospital program manager.

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Their eggs, soft, porous and the size of ping-pong balls, develop into male or female offspring depending on the temperature of incubation. Once the hatchlings emerge, their frenzy toward the water begins, guided by the silky reflection of moonlight on the waves.

Their path to the sea presents its own threats: Hatchlings risk dehydration (from taking too long to reach the ocean), disorientation (from other sources of light on the beach) and predation (from ghost crabs and night herons hungry for their next meal).

Just one in 1,000 hatchlings will survive to adulthood. Those that do become stewards of a healthy ocean.

As a keystone species, sea turtles influence multiple levels of marine food webs, balancing the populations of jellyfish, crustaceans, seagrass and algae, which different sea turtle species consume.

“If you are a person on the Earth, and you want to see ecosystems function properly,” Lasala said, “you explicitly want sea turtles to continue.”

Their eggshells, hatched or unhatched, supply nutrients that cycle through the beach’s ecosystem. Dune vegetation, which thrives off high levels of nitrogen and phosphorus, grows in the egg-nourished sand.

When storms hit, sending surges as high as 15 feet onto the beach, these plants stabilize the dunes, limiting beach erosion and lessening potential flooding.

But this protection isn’t foolproof.

After Hurricanes Helene and Milton, the loss of dunes on Anna Maria Island in Manatee County stunned the island’s turtle watch director, Kristen Mazzarella.

“It’s a big shock to see a beach go from dunes with sea oats and sea grapes and other dune plants to just a flat piece of sand,” she said.

#AskJAXTDY: Does beach renourishment disturb sea turtles?

Anna Maria’s beach still exists, reopened to the public Oct. 26. But it’s noticeably narrower now, Mazzarella said.

Such environmental impacts become a cycle of harm: Less beach means fewer sea turtles. Fewer sea turtles mean fewer sand dunes. Fewer dunes leave beaches more vulnerable to erosion.

If the stretch of beach on Anna Maria Island remains flat by next turtle season, new nests could be at a greater risk of inundation, Mazzarella said. The lack of dunes also leaves hatchlings more exposed to artificial lighting, potentially veering them off their course to the sea.

“Warning bells go off in my head,” Mazzarella said.

How the heat takes a toll

Rising global temperatures, which scientists say helped intensify the recent storms, are a concern on land as much as in water — even nests that make it on the sand aren’t guaranteed proper development in a warming world.

Because the sex of sea turtles is determined by their incubation temperature, researchers expect the increasing heat to induce more female than male hatchlings.

“In the short term, that’s not necessarily a bad thing,” Lasala, the sea turtle biologist, explained. It means more offspring and therefore, a larger population.

But in the long run the skewed ratio of females could be detrimental, Lasala added. “You won’t have enough males to continue to populate.”

As the sea turtle program manager at Mote Marine Laboratory, Lasala’s research examines turtle paternity, establishing a baseline number of successful males near the coast of Sarasota and Manatee counties. It’s an important checkpoint for assessing how this number might change in the future.

Already, the climbing temperatures are threatening the viability of all hatchlings. Research on loggerhead sea turtles in South Florida suggests a link between hotter air and a decline in emergence success, meaning fewer eggs produce hatchlings that leave the nest.

These challenges lie beneath the sand, not necessarily reflected in nest count data. Nests in Florida reached a record high number in 2023, but population-wide conclusions require long-term data sets, said Jack Brzoza, a sea turtle biologist at Sanibel-Captiva Conservation Foundation.

“Nest counts are one part of the picture,” Brzoza said. “You can have as many nests laid as you want. If none of them hatch, that’s really not contributing much.”

Since 1989, the Florida Fish and Wildlife Research Institute has measured trends in nesting counts based on a subset of nesting beaches. According to the index, observed numbers of loggerhead turtle nests have widely fluctuated by year. The period overall, however, shows a stable trend — and “many more years of standardized nest counts are needed” to determine whether the fluctuation patterns are natural or worthy of concern, the index says.

Nurturing recovery 

When nesting data does tell a story, it’s one about the importance of long-term conservation efforts.

Sea turtle conservation policies took off in the 1970s and ’80s, with fishing gear regulations, fines for harming nests and a ban on sea turtle hatchery. Loggerhead and green sea turtles were listed as endangered in 1978. The following year, Florida’s wildlife agency launched its annual statewide nesting beach survey, an effort that coordinates conservation groups, researchers and municipal agencies to amass data.

While local turtle monitoring in the state began in the late 1950s, many aspects of conservation work on the beach haven’t changed. Researchers and volunteers follow the turtle tracks in the sand, count and tag the nests and tape them off with wooden stakes.

If passing beachgoers eye the activity with curiosity, the explanation from groups like Mote Marine Laboratory’s and Anna Maria Island Turtle Watch comes with a call to action: Be careful of leaving holes in the sand, they tell them, and turn off any lights near the beach at night.

The recent positive spikes in nest counts wash that conservation history ashore: “[Record sea turtle nesting] is likely a consequence of conservation actions that were put in place 30 years ago,” said Dr. James “Buddy” Powell, executive director of research at Clearwater Marine Aquarium.

Hatchlings that survive because of these conservation efforts might outlive the people doing them. The lifespan of a sea turtle is 50 to 100 years. By the time the creature begins reproducing, at 20 to 30 years old, a new generation of researchers and volunteers will likely be waiting for them on the sand.

Still, climate change and the expansion of sea turtle research over the past decades bring as many new questions around conservation as answers.

“Thirty years ago … the solutions were kind of simple,” Powell explained. Stop the fishing and hunting of sea turtles. Protect their nesting beaches. Prevent the poaching of eggs.

Today’s conservation conversations grapple with more complex challenges related to climate change — whose effects threaten not just sea turtles but humans.

“I don’t know of any renourishment projects of beaches that are done just for turtles,” Powell said. Property owners and tourism industries benefit from protecting sea turtles because all face the same essential challenges, he added.

Continued research and education on the need for sea turtle conservation are crucial for influencing policymaking, multiple researchers said. Public awareness, Powell said, creates political will.

“What’s good for the animals, what’s good for the habitat, ends up also being good for us.”