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Loggerhead turtle nests facing new threats

Posted at 2:27 PM, Jun 23, 2017
and last updated 2017-06-24 01:42:33-04

From plastic bags to boats, sea turtles face a lot of threats in South Florida.

And thanks to rehab centers like Loggerhead Marinelife Center in Jupiter, the turtles have continued to be a huge part of our eco-system.

But new research says there are more threats than ever before, so local researchers are working overtime this summer to check hundreds of sea turtle nests.

They say according to their data, rising sand and air temperatures over the past couple of years are literally "cooking" turtle eggs before they can even hatch.

Data manager Sarah Hirsch of the Loggerhead Marinelife Center is spending all summer digging holes on the beach.

"Getting to work on the beach every day isn't too shabby!" she said in an interview Friday morning.

She's not looking for gold, but for new insight into how our environment is impacting the endangered sea turtle population.

"This is one of the most important nesting grounds in the United States," she said. "One of the things we've noticed in the past few years that it's gotten very hot and dry in the summer months."

Sea turtle eggs are very sensitive to temperature changes. When the sand is too hot, the eggs don't stand a chance.

"There is a lethal temperature and so with these hot and dry summers we've had recently...that's definitely a cause for concern," said Hirsch.

2016 was one of the worst loggerhead egg counts they've seen in years.

"Unfortunately, last year was again just so hot and dry that our emergence success dropped down to 46 percent," said Hirsch.

That's compared to 68 percent in 2015 and 77 percent in 2014.

Researchers say green sea turtles didn't see as much of a drop, with 72 percent in 2016 compared to 79 percent in 2015. Green sea turtle emergence success in 2014 was similar to what we saw in 2016 at 73 percent.

Leatherback nests had a slightly higher emergence success in 2016 39 percent compared to 2015 (36.40%) and in 2014, leatherback emergence success was much higher at 68 percent.

According to Loggerhead Marinelife Center, the hot and dry conditions in 2016 were especially pronounced in July when the loggerhead nests are at peak incubation, which could explain the lesser impacts to leatherback and green turtle emergence success.

"Yes, climate has changed over time, but the difference now is it's changing very very quickly," said Hirsch.

Hirsch fears the trend continues this year, which is why her team is counting hatched eggs every morning.

"So we wait three days before we dig and inventory what's down here," she said. "We come out here every single morning March 1 through October 31."

Hirsch and her team spends the morning checking the turtle nesting sites, which are holes dug by the female turtles themselves. The loggerheads only lay their eggs at night throughout the summer.

"She's doing all of this with her rear flippers," Hirsch said, as she pushed apart sand from a two foot hold. "This is a loggerhead, so it's the shallowest of the three species that lay here."

While counting a particular nest on Juno Beach Friday, she found the nest had 114 eggs. All but two hatched.

"Very successful nest. Unfortunately, those hatchlings, once they've gotten out of the nest, their chances are not great," she said. "One in a thousand to one in 10,000 survive to maturity."

The climate also impacts the sex of the turtle, so male to female ratios can be uneven.

"The sex of the turtle is dependent on the temperature that the eggs are incubating in," Hirsch said. "We want to know if we're producing a good ratio of males to females."

Marguerite Koch, a Florida Atlantic University marine biology and ecology graduate professor said data on rising sea levels show potential threats to where turtles can nest.

"Even though we live in South Florida, we need to look north and south. North to Greenland's ice sheet and south to the Antarctic ice sheet," she said. "Yes, climate has changed over time, but the difference now is that it's changing very, very quickly."

She says most of the rising air temperatures we see in the world are going into the oceans.

"We all know that once you heat up water, it stays warm for a very long time," she said. "If we start seeing these ice sheets melting, then we're really going to be in trouble."

Koch studies the ocean's oxygen solubility, which she says is gradually being reduced and is causing more problems for animals.

For now, loggerhead researchers will keep an eye on these nests.

"And make sure that we know these turtles can survive in the future," said Hirsch.

Loggerhead Marinelife Center has the longest running research data sets in the country, which makes this area a pivotal area for studying the habits of sea turtles.

"We can look at trends over long periods of time. Not only is the climate changing over those long periods of time but sea turtles reach maturity at 25 or 30 years," said Hirsch. "So the hatchlings that are leaving our beaches now aren't going to be returning to these beaches for another 25 to 30 years. The beach is probably going to look very different."

She added, "Having those long term data sets is essential for us to understand what the populations are doing and how humans are impacting the population."

Researchers are also checking to see if the turtles are adapting in any way. Are they showing up farther north where it's cooler or earlier than ever before when it's not as hot? They hope research this year -- which ends in October -- will answer that question.

If you ever come across turtles on the beach, click here to learn what to do.