Saving Sea Turtles With a Lights-Out Policy in Florida
for National Geographic News
|March 10, 2003|
For hatchling sea turtles, artificial light is a killer. Instinct drives
them from their nests on beaches towards the brightest horizon, ideally
the waterline on an undeveloped coast.
But the bright lights of coastal developmentstreetlamps, illuminated parking lots, and buildingscan disorient nesting, egg-laden female turtles and lure newly-hatched baby turtles towards artificial light sources. As hatchlings turn away from the sea to cross into streets and parking lots, they are invariably killed.
A program to darken the coastline of Sarasota County in central Florida, an area with the highest turtle nest density on the Gulf of Mexico, has substantially brightened the prospects for the sea turtle populationwithout sacrificing the safety or security of human residents.
Shielding Lights; Saving Turtles
"The darker the beaches, the more attractive they are for the female turtles and the less disorienting for the hatchlings," explained Kenya M. Leonard, an environmental specialist for Sarasota County's Environmental Services Coastal Resources program and administrator of the county's Sea Turtle Protection Program.
"I have yet to find a lighting situation that can't be properly resolved to protect both the residents and the turtles," she added.
According to Beth Brost, of the Florida Fish and Wildlife Conservation Commission, the beaches of Sarasota County have the highest density (58 nests per kilometer) of loggerhead turtle nesting on the west coast of Florida.
With 35 miles (56 kilometers) of warm, white sand beaches, Sarasota County was home to an average of 42 percent of the loggerhead turtles that nested along Florida's west coast during the past five years.
For the past 10 years, an average of 3,104 loggerhead nests have been documented each year along the county beaches during the May through October nesting season.
The turtle species nesting on Sarasota County beaches include the threatened loggerhead and endangered green sea turtles. In the last five years, nests also have been documented for the rare Kemp's ridley and leatherback sea turtles.
"We have miles of suitable nesting habitat. One beach in particular, Casperson beach on Manasota Key, has no high rises or armored beaches and draws the greatest number of turtles. Having a healthy dune system there also helps," Leonard explained.
Home Sweet Home
Hatchlings that successfully make the trek from their nests to the relative safety of the gulf and ocean waters find sanctuary from predators in large, floating beds of sargassum seaweed far offshore.
Following sexual maturity 20 to 50 years later, natal hominga behavior of returning to where one was born, and in a turtle's case, employing an instinctual ability to navigate using the Earth's magnetic fieldleads the females back to the beaches where they hatched to make their own nests. Though, if their natal beaches are brightly lit, the females may avoid nesting there.
If a suitable nesting site cannot be found nearby, female turtles may expend valuable energy looking for one, potentially leading to a decrease in the number of nests she is able to lay [fill] that season, Leonard said. Each nest may contain 100 eggs, the size of Ping-Pong balls.
It takes approximately two months for sea turtle eggs to incubate and hatch, a range of 43 to 75 days.
On average, females nest every other year. Some turtle species may nest more than six times in a single season, usually on the same stretch of beach. Because the females can mate with several males and store the sperm, hatchlings have multiple fathers, thus maximizing the population's genetic diversity.
Early Efforts and Missteps
While the importance of providing a safe habitat for the nesting females and their hatchlings was recognized long ago, early protection efforts depended upon voluntary enforcement and were ineffective. Creation of artificial hatcheries and placing restraining cages over nests proved counter-productive.
"It was very frustrating because many of these measures were harming, not helping the turtles," Leonard said.
That's when preserving the night became a priority.
"Instead of trying to make the turtles adapt, we realized that we had to change our attitudes and behaviors," she explained.
Adopted in 1997, the county's Sea Turtle Protection Ordinance involves public education, enforcement of lighting regulations and required review of all new structures and street lighting.
"Prior to adoption of the county ordinance, there were public education efforts aimed at creating a voluntary compliance with keeping artificial lighting off of the beaches. But, they were not very successful and the number of adult and hatchling disorientations was alarming," said Jerris Foote, program manager for Sea Turtle Conservation and Research at Mote Marine Laboratory in Sarasota. "We've seen tremendous results since the county started the program to keep beaches dark," said Foote.
Improvement came one darkened light bulb at a time. Although disorientations still occur, Leonard's goal is to once again see the beaches become a haven for female sea turtles and their hatchlings.
For the past four years, the Sarasota County scientist has systematically worked with the owners of the more than 700 coastal properties, educating them in how to safely darken their beaches.
Photographic surveys taken over the years prove that the beaches are getting darker and safer for the sea turtles. Numerous other communities in Florida have adopted or are considering sea turtle protection ordinances.
"I believe we are successfully changing the mindset of the coastal residents," Leonard said. "That's good for future generations of sea turtles and for future generations of humans who will be able to enjoy having these creatures on their beaches."
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