Rain from Tropical Storm Debby threatens Harbor Island turtles. 31 drowned in one nest

As usual, newly hatched loggerhead turtles the size of cookies are scampering across South Carolina beaches to begin what could be long lives in the Atlantic Ocean with periodic returns to land to lay their own eggs, continuing the cycle of life. But not every hatchling makes it out of the nest. Raccoons, fire ants and ghost crabs will claim some. And this summer, an inundation of rain from Tropical Storm Debby has become an additional threat to the wee turtles, the state reptile of South Carolina.

Just Wednesday morning, volunteers at Harbor Island east of Beaufort discovered 31 dead hatchlings in one nest chamber as they made their rounds patrolling turtle nests. Volunteers presumed the hatchlings drowned because water had pooled in the bottom half of the nest, says Jan Grimsley, principal sea turtle permit holder for Harbor Island, who leads a team of volunteers who monitor the nests each year.

The pooling water as a result of a saturation of rain seems to be a bigger threat to the baby turtles than storm surge, which can wash away entire nests containing up to 120 eggs, Grimsley said.

“Pooling water — the inability of soil to drain effectively — will be our biggest problem,” Grimsely says.

Although the rainfall is a concern, no one storm season is a total loss for sea turtles, Grimsley is quick to point out.

Just as notable, she says, is that Tropical Storm Debby has not swept away a single nest, which was a concern before the storm began lashing the South Carolina coast with heavy rains.

“We’ve had some really great success this season prior to Debby-associated rains,” Grimsley said.

Although 31 hatchlings did not make it out of this particular nest, it means that 92 survived because a 123 eggs had hatched, Grimsley also points out.

The major nesting areas for the loggerhead are the undeveloped beaches of the western Atlantic including the Lowcountry Sea Islands . Adults, which can reach 300 pounds and live 80 years, lay eggs in South Carolina from May to October. The eggs incubate for a few months before hatching.

That’s the same stretch that’s been slammed with record rainfall this week.

At Harbor Island, 38 nests continue to incubate out of 55 that have been documented this year. To date, 1,683 hatchlings have manged to burst from their underground chambers before making a mad crawl to the ocean.

Now it’s a waiting game to see how many emerge.

The eggs can stand the usual rising of the tide, which is irregular and drains, Grimsley said.

Turtles have even adapted nesting strategies to accommodate hurricanes and tropical storms, says Grimsley. For example, loggerheads nest three to five times within a nesting season and lay an average 120 eggs each time before taking a year off and beginning the process again. Turtles that nested on Harbor Island in 2024 probably won’t be back again until 2026.

“This is why they lay so many nests and so many eggs, to balance it all out,” Grimsley says.

“But what we’ve experienced over the last few days is so much water all at once,” Grimsley adds. “I will say the rain may be our biggest problem. Because the water pools when water can’t drain.”

Volunteers continue to monitor the nests even during the storm, showing up at daybreak to walk the beaches looking for signs of a “boil.” That’s when hatchlings burst from underground nests in unison and make a break for the sea, leaving behind tiny tracks. Once in the water the 2-inch-long hatchlings will swim continuously for 36 hours to escape predators before finding refuge, maybe on a clump of seaweed.

It’s possible that some have emerged during Tropical Storm Debby and the storm washed away their tracks.

“Literally, these things are the size of a cookie so their tracks, they are not huge,” Grimsley said.

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