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Keeping the beach dark for sea turtle nesting season

March 10, 2015
By BRIAN WIERIMA (bwierima@breezenewspapers.com) , Island Reporter, Captiva Current, Sanibel-Captiva Islander

With warmer temperatures on the way to Southwest Florida, it's time to enjoy the sun during the day, but turning the lights out on the beach at night.

The Loggerhead sea turtle nesting season officially starts April 20 this year, which is a couple of weeks earlier than normal due to the water temperatures varying this season. The nesting season will run from late April to early May and into August or even into September.

What that means for people on Sanibel is to keep the beaches dark and not disturb the female turtles coming ashore to build nests and lay eggs, or the hatchlings which will be burrowing out of the sand and hopefully heading for the waters of Gulf of Mexico.

Article Photos

A newly hatched sea turtle starts the long trek to the Gulf of Mexico from a Sanibel beach. (Photo by Barb Bergwerf)

"Right now, the Loggerheads are in mating season and starting in May, females start coming up on the beach at night, and it's almost always at night to build their nests, because predators are more prevalent during the day," said Kelly Sloan, who is a biologist and sea turtle coordinator at the Sanibel-Captiva Conservation Foundation (SCCF).

A female sea turtle will sometimes do a "false crawl", which happens when they turn around and head back to the ocean without laying their eggs.

"That happens almost about 50-percent of the time, we don't know why, but it could be due to the turtle getting scared off by lights, a predator or by a human," Sloan said.

Also, the females are left to fend for themselves on the beach, because males very rarely join their partners on the sandy journey.

But if the female finds the beach to her liking, she starts the process of constructing her nest for the eggs. The turtle will use her backflippers to make a nest chamber, which resembles an inverted lightbulb, with the entry skinny and the back of it wider.

"It's amazing to watch them carve out a nest chamber, because of how skilled they are at doing it," Sloan said.

When the nest is ready to host the eggs, the sea turtle will lay an average of 110 eggs, which look a lot like ping-pong balls.

The turtle will cover up the nest to disguise it from predators and her job as being a mother ends, as she heads back out to sea, never to return before the hatchlings break out of their shells.

"Each female lays up to three to five nests each season, and they nest every two to three years," Sloan said. "Although they average laying 110 eggs, I've seen as few as 20 or as many as 200."

It will take approximately two months of incubation before the baby sea turtles are ready to peck out of their shelled world, using an egg tooth as a tool.

Much like their mother's instinct, the majority of the time, the hatchlings will break out of their shell at night, which is determined by the temperature on the outside. The cool weather during the evening hours is a sign for the hatchlings to start their quest from nest to sea.

"They all move together at once and all boil out of the nest at the same time," Sloan said.

The hatchlings will be drawn by the brightest light on the beach, in which throughout history, has been the moonlight glittering off the ocean waters. But with human coastal development running rampant over the last several decades, artificial light has trumped the glare of the moon, thus setting the hatchling off course and many times, away from the ocean.

The energy the hatchlings use comes from a yolk sack attached underneath their bellies. The gas tank lasts up to three days, after that, the hatchling had better be in the water, or they will weaken and become dehydrated, which leads to death.

"Last year, we had a record number of disorientations of hatchlings on Sanibel and we think it was due to interior lighting," Sloan said. "The big thing people can do is close their blinds at night and shut off their exterior lights. And when on the beach at night, avoid using flash photography and flashlights."

Sanibel has been one of the more progressive communities in the nation for protecting sea turtles. The Sanibel City Council just passed their Dark Skies ordinance Tuesday, March 3, which prohibits glaring, unshielded or up-turned lights on the island. Part of it is to protect the sea turtle hatchlings when they are making their haul to the Gulf and not be affected by artificial light pollution.

Even though lights at night is a threat to the hatchlings, there are many other factors which can prevent them to making it to home waters.

Predators such as coyotes, raccoons, seagulls, fire ants and ghost crabs snack on the helpless hatchlings, while holes on the beach dug by beach goers can be a fatal obstacle, as well.

"Sea turtles can't reverse, and once they fall in in a hole, they can't get out," Sloan added. "So it's suggested to fill in your holes on the beach. Plastics in the water are also harmful, because the adults can ingest them or get entangled in the material.

"People can also take off their beach furniture, because sea turtles can get entangled in them, as well."

Even if the hatchlings make it through the land obstacles, they have a long haul in the ocean where sharks and other marine predators are a threat.

"Only one in 1,000 survive to adulthood," Sloan said.

The Loggerhead sea turtle is listed as a threatened species, which means they have the possibility of becoming endangered within the foreseeable future under the U.S. Federal Endangered Species Act.

They are listed as endangered by the International Union for Conservation of Nature and Natural Resources, with the biggest threat to the species being fishing gear (longlines or gillnets) and the second biggest threat is the loss of nesting habitat due to coastal development, predation of nests and human disturbances, which include lighting.

Sanibel also has Green and Leatherback sea turtles nesting on its beaches, but those are much more rare than Loggerheads.

With a Loggerhead sea turtle hatchling already up against big odds to make it to adulthood, people can do their part to not add any more obstacles in their way, by either pulling the shades or by just by flipping the switch to off.

 
 

 

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